JP6287310B2 - Electronic component, method for manufacturing electronic component, and method for manufacturing electronic device - Google Patents

Description

  The present invention relates to an electronic component, an electronic component manufacturing method, and an electronic device manufacturing method.

  Solder is widely used for joining electronic components. As one of the joining techniques using solder, there is a technique for joining a joining layer such as a solder paste and a bump such as a solder ball. For example, a technique is known in which bumps having a melting point higher than that of solder contained in the bonding layer are bonded to the bonding layer at a temperature higher than the melting point of the bonding layer and lower than the melting point of the bumps.

JP 2013-123078 A JP 2009-277777 A

  The solder bonding technology as described above enables solder bonding at a relatively low temperature below the melting point of the bump, while depending on the type and composition of the solder used, the desired mechanical characteristics of the solder bonding portion to be formed. In some cases, sufficient bonding reliability could not be obtained.

According to one aspect of the present invention, a first substrate that includes a substrate having an electrode and a bonding layer provided on the electrode, the bonding layer including a first element and a second element having a eutectic composition. A first layer containing solder, and a first layer containing the first element and the second element that are laminated with the first layer and have a non-eutectic composition and a composition range in which a solidus temperature shows a eutectic point . An electronic component having a second layer containing two solders is provided.

  Moreover, according to one aspect of the present invention, a method for manufacturing the electronic component as described above and a method for manufacturing an electronic device using the electronic component as described above are provided.

  According to the disclosed technique, it is possible to realize a solder joint that exhibits desired mechanical characteristics and has high joint reliability.

It is a figure which shows an example of the electronic component which concerns on 1st Embodiment. It is a state figure of Sn-Bi solder. It is a figure which shows an example of the formation method of the electronic component which concerns on 1st Embodiment. It is a figure which shows another example of the formation method of the electronic component which concerns on 1st Embodiment. It is a figure which shows an example of the joining method of the electronic component which concerns on 1st Embodiment. It is a figure which shows the change of the mechanical characteristic by Bi addition to Sn-Ag solder. It is a figure which shows the joining method of the electronic component which concerns on another form. It is a figure which shows an example of an electronic device. It is a figure which shows an example of the electronic component which concerns on 2nd Embodiment. It is a figure which shows an example of the electronic component which concerns on 3rd Embodiment. It is a figure which shows an example of the electronic component which concerns on 4th Embodiment. It is a figure which shows an example of the electronic component which concerns on 5th Embodiment. It is a figure which shows an example of the formation method of the electronic component which concerns on 6th Embodiment. It is a figure which shows an example of a circuit board. It is a figure which shows an example of a semiconductor element. It is a figure showing an example of a semiconductor device.

First, the first embodiment will be described.
FIG. 1 is a diagram illustrating an example of an electronic component according to the first embodiment. FIG. 1 schematically shows a cross-section of an essential part of an example of an electronic component according to the first embodiment.

An electronic component 1 shown in FIG. 1 includes a component main body (substrate) 10 provided with an electrode 20 and a bonding layer 30 provided on the electrode 20.
The component body 10 of the electronic component 1 is, for example, a circuit board, a semiconductor element (semiconductor chip), or a semiconductor device (semiconductor package) using the semiconductor element. In addition, the structural example of the component main body 10 is mentioned later (FIGS. 14-16).

  At least one electrode 20 is provided on the component main body 10, for example, on the surface 10a thereof. FIG. 1 illustrates one electrode 20 provided on the surface 10 a of the component body 10. The electrode 20 provided on the surface 10a is provided at a position corresponding to the electrode of the counterpart electronic component to be soldered to the surface 10a side of the electronic component 1. Various conductive materials can be used for the electrode 20. For example, a conductive material such as copper (Cu), silver (Ag), gold (Au), nickel (Ni), or aluminum (Al) can be used for the entire electrode 20 or a part of the electrode 20.

  Although the case where the electrode 20 is provided on the front surface 10a of the component main body 10 is illustrated here, at least one electrode 20 may be provided on the back surface 10b as well as the front surface 10a of the component main body 10. In this case, the electrode 20 provided on the back surface 10b is provided at a position corresponding to the electrode of the counterpart electronic component to be soldered to the back surface 10b side of the electronic component 1.

  The bonding layer 30 is provided on the electrode 20 of the component body 10. In addition to the electrode 20 on the front surface 10a, the bonding layer 30 can also be provided on the electrode 20 on the back surface 10b when the electrode 20 is provided on the back surface 10b. Solder is used for the bonding layer 30. The bonding layer 30 includes a first layer 31 and a second layer 32 containing eutectic solder containing a first element and a second element. In the example of FIG. 1, a first layer 31 is provided on the electrode 20 of the component body 10, and a second layer 32 is provided on the first layer 31.

  One of the first layer 31 and the second layer 32 of the bonding layer 30 is eutectic solder, and the other is non-eutectic solder. In the example of FIG. 1, solder having a eutectic composition containing the first element and the second element is used for the first layer 31, and the non-layer containing the first element and the second element is used for the second layer 32. Eutectic solder is used. The second layer 32 of the bonding layer 30 can have a single layer structure using a non-eutectic composition solder or a laminated structure using a non-eutectic composition solder. Here, first, the case where the second layer 32 has a single-layer structure using a solder having a non-eutectic composition will be described as an example.

  For example, tin (Sn) -bismuth (Bi) solder can be used as the solder of the first layer 31 and the second layer 32 of the bonding layer 30. In this case, Sn is used as the first element contained in the solder of the first layer 31 and the second layer 32. Bi is used as the second element contained in the solder of the first layer 31 and the second layer 32. To the solder of the first layer 31 and the second layer 32, elements such as Ag and antimony (Sb) of a certain amount, for example, less than 1 wt% to several wt% can be added to Sn and Bi. In addition, the solder of the first layer 31 and the second layer 32 may contain inevitable impurities that are difficult to avoid in the manufacturing of the electronic component 1.

  The first layer 31 of the bonding layer 30 is provided on the electrode 20 of the component body 10 as, for example, a solder paste containing solder containing the first element and the second element as described above. For example, the second layer 32 of the bonding layer 30 is provided on the first layer 31 as a solder paste containing solder containing the first element and the second element as described above. The solder paste of the first layer 31 and the solder paste of the second layer 32 include, for example, solder powder containing the first element and the second element as described above (for example, 80 wt% to 95 wt%), flux, and the like ( For example, 5 wt% to 20 wt%) is included.

  The solder of the first layer 31 and the second layer 32 of the bonding layer 30 is not limited to the Sn—Bi solder as described above, and another eutectic solder can be used. For example, Sn—Ag solder containing Sn and Ag, Sn—Zn solder containing Sn and zinc (Zn), Sn—In solder containing Sn and indium (In), Sn and lead (Pb) Sn-Pb-based solder containing copper can also be used.

  Hereinafter, a case where Sn—Bi solder is used as the solder of the first layer 31 and the second layer 32 of the bonding layer 30 will be described as an example. In this case, the first layer 31 of the bonding layer 30 includes eutectic Sn—Bi solder containing Sn as the first element and Bi as the second element. The second layer 32 of the bonding layer 30 includes Sn—Bi solder having a non-eutectic composition containing Sn as the first element and Bi as the second element.

  A state diagram of Sn-Bi solder is shown in FIG. In FIG. 2, the horizontal axis represents Bi atomic% [at%] (lower) and weight% [wt%] (upper), and the vertical axis represents temperature T [° C.]. In FIG. 2, P represents a solid phase line, and Q represents a liquid phase line. α and β represent a solid phase, and L represents a liquid phase.

  As shown in FIG. 2, Sn-Bi solder shows a eutectic phase diagram. From FIG. 2, the eutectic composition of Sn—Bi solder is a composition of Sn 43 wt% and Bi 57 wt%, and the eutectic point is 139 ° C. The eutectic Sn—Bi solder is heated from the solid phase (α + β) state and changes to the liquid phase (L) when the eutectic point exceeds 139 ° C.

A eutectic Sn-Bi solder having such a property that changes state from a solid phase to a liquid phase by heating is used for the first layer 31 of the bonding layer 30.
On the other hand, a composition deviating from the eutectic composition, that is, a non-eutectic composition Sn—Bi solder exhibits the following state changes.

  For example, when the Bi composition (21 wt% to 57 wt%) is smaller than the Bi composition (57 wt%) of the eutectic composition, it is heated from the solid phase (α + β) state, and when the eutectic point exceeds 139 ° C., the solid phase (α ) And the liquid phase (L) coexist. In the case of a Bi composition (21 wt%) as shown by the line O1 in FIG. 2, the Sn—Bi solder (single element) changes to a liquid phase (L) at a temperature T1 exceeding the eutectic point of 139 ° C.

  Further, when the Bi composition (57 wt% to 99.9 wt%) is larger than the Bi composition (57 wt%) of the eutectic composition, the solid phase (α + β) is heated and the eutectic point exceeds 139 ° C. It changes to the state where (β) and the liquid phase (L) coexist. In the case of a Bi composition (75 wt%) as shown by the line O2 in FIG. 2, the Sn—Bi solder (single element) changes to a liquid phase (L) at a temperature T2 above the eutectic point of 139 ° C.

A non-eutectic composition Sn—Bi solder having such properties is used for the second layer 32 of the bonding layer 30.
The electronic component 1 having the above configuration is formed as follows, for example.

  FIG. 3 is a diagram illustrating an example of a method for forming an electronic component according to the first embodiment. FIG. 3A is a schematic cross-sectional view of an essential part showing an example of a preparation process of a component body, FIG. 3B is a schematic cross-sectional view of an essential part showing an example of a first layer forming process of a bonding layer, and FIG. FIG. 3D is a schematic cross-sectional view of the relevant part showing an example of a second layer forming step of the bonding layer, and FIG. 3D is a schematic cross-sectional view of the relevant part showing an example of a state after the formation of the joining layer.

  First, a component main body 10 having an electrode 20 as shown in FIG. For example, a circuit board, a semiconductor element, or a semiconductor device having the electrode 20 is prepared. The electrode 20 is formed by using a film forming technique such as a sputtering method or a plating method, a patterning technique using photolithography and etching, a planarization technique such as machining or polishing.

  After the preparation of the component body 10, the first layer 31 of the bonding layer 30 is formed on the electrode 20 as shown in FIG. At that time, for example, a solder paste prepared by mixing Sn—Bi solder powder having a eutectic composition with a flux is prepared, and the solder paste is formed on the electrode 20 using a printing method. The solder paste used for forming the first layer 31 may contain, for example, a rosin as a flux component, a solvent, an activator, a thixotropic agent, and the like. In this case, natural rosin, polymerized rosin, or the like can be used as the rosin. As the solvent, butyl carbitol, benzyl benzoate, or the like can be used. As the activator, an activator such as halogen, organic acid or amine can be used. For the thixotropic agent, hardened castor oil or the like can be used.

  Such solder paste is supplied onto the electrode 20 using a first mask 40 such as a metal mask having an opening 41 at a position corresponding to the electrode 20 as shown in FIG. Layer 31 is formed. In that case, the amount of the solder paste supplied onto the electrode 20 can be adjusted by adjusting the size and thickness of the opening 41 of the first mask 40 to be used.

  After the formation of the first layer 31, the second layer 32 is formed on the formed first layer 31, as shown in FIG. At that time, for example, a solder paste prepared by mixing Sn-Bi solder powder having a non-eutectic composition with a flux was prepared, and the solder paste was formed on the electrode 20 using a printing method. Formed on the first layer 31. Similar to the solder paste used for forming the first layer 31, the solder paste used for forming the second layer 32 may contain, for example, rosin as a flux component, solvent, activator, thixotropic agent, and the like.

  A second mask 50 such as a metal mask having an opening 51 at a position corresponding to the electrode 20 of the component main body 10 and the first layer 31 previously formed as shown in FIG. Then, the second layer 32 is formed on the first layer 31. In that case, for example, a second mask 50 used for forming the second layer 32 is separately provided on the component main body 10 after the first mask 40 of FIG. Alternatively, after the formation of the first layer 31 in FIG. 3B, the first mask 40 is left without being removed, and a mask used for forming the second layer 32 is stacked thereon, so that the structure shown in FIG. A second mask 50 like this is obtained. The amount of solder paste supplied onto the first layer 31 can be adjusted by adjusting the size and thickness of the opening 51 of the second mask 50.

  After the formation of the second layer 32, the second mask 50 is removed as shown in FIG. Thereby, the electronic component 1 in which the bonding layer 30 including the first layer 31 and the second layer 32 is formed on the electrode 20 of the component body 10 is obtained.

The electronic component 1 can be formed using a method as shown in FIG.
Here, the case where the first layer 31 and the second layer 32 of the bonding layer 30 are formed using a solder paste is illustrated. In addition, the first layer 31 can be formed on the electrode 20 and the second layer 32 can be formed on the first layer 31 by using, for example, a plating method.

  FIG. 4 is a diagram showing another example of the electronic component forming method according to the first embodiment. 4A is a schematic cross-sectional view of an essential part showing an example of a resist forming process, FIG. 4B is a schematic cross-sectional view of an essential part showing an example of a first layer forming process of a bonding layer, and FIG. FIG. 4D is a schematic cross-sectional view of the relevant part showing an example of a state after the formation of the bonding layer.

  In this method, first, a component main body 10 in which a resist 60 having an opening 61 is formed at a position corresponding to the electrode 20 as shown in FIG. The resist 60 is a resist used when forming the electrode 20 of the component body 10 or a resist formed separately after the formation of the electrode 20 of the component body 10.

  A Sn-Bi solder having a eutectic composition is formed with a predetermined film thickness on the electrode 20 in the opening 61 of the resist 60 of the component body 10 in which such a resist 60 is formed by using a plating method. As shown in FIG. 4B, the first layer 31 is formed. Next, on the first layer 31 in the opening 61 of the resist 60, Sn—Bi solder having a non-eutectic composition is formed with a predetermined film thickness using a plating method, as shown in FIG. The second layer 32 is formed. In this way, the first layer 31 and the second layer 32 are sequentially formed using a plating method.

  After the formation of the first layer 31 and the second layer 32, the resist 60 is removed as shown in FIG. Thereby, the electronic component 1 in which the bonding layer 30 including the first layer 31 and the second layer 32 is formed on the electrode 20 of the component body 10 is obtained.

The electronic component 1 can also be formed using a method as shown in FIG.
Further, the first layer 31 and the second layer 32 of the bonding layer 30 of the electronic component 1 can be formed by using a sputtering method, a vapor deposition method, or a dipping method in addition to the printing method and the plating method as described above. is there.

  The electronic component 1 as described above can be bonded to other electronic components using the bonding layer 30 provided on the electrode 20. Examples of other electronic components joined to the electronic component 1 include a circuit board, a semiconductor element, and a semiconductor device.

  Examples of the combination of the electronic component 1 to be joined and another electronic component include a combination of a circuit board and a semiconductor element, a combination of a circuit board and a semiconductor device, and a combination of a semiconductor element and a semiconductor device. In addition, combinations of the electronic component 1 to be joined and other electronic components include a combination of circuit boards, a combination of semiconductor elements, and a combination of semiconductor devices.

  FIG. 5 is a diagram illustrating an example of a method for joining electronic components according to the first embodiment. FIG. 5A is a schematic cross-sectional view of an essential part showing an example of a state before joining an electronic component, FIG. 5B is a schematic cross-sectional view of an essential part showing an example of an electronic component joining process, and FIG. It is a principal part cross-sectional schematic diagram which shows an example of the state after joining.

First, as shown in FIG. 5A, the electronic component 1 as described above and the electronic component 100 to be joined to the electronic component 1 are prepared.
The electronic component 100 is, for example, a circuit board, a semiconductor element, or a semiconductor device. The electronic component 100 has a component main body 110 and an electrode 120 provided on the surface 110a. The electrode 120 is provided at a position corresponding to the electrode 20 provided on the electronic component 1 to be joined. Various conductive materials such as Cu can be used for the electrode 120. A bump 130 is provided on the electrode 120 so as to protrude toward the surface 110 a of the component main body 110. The bump 130 is made of Sn-based solder having a higher melting point than the bonding layer 30 provided on the electrode 20 of the electronic component 1 to be bonded, such as Sn solder, Sn-Ag solder, Sn-Ag-Cu solder, or the like. Sn-based solder is used. FIG. 5 illustrates a case where a ball-shaped bump (solder ball) using Sn-based solder is provided on the electrode 120 as the bump 130.

As shown in FIG. 5A, such an electronic component 100 has its electrode 120 disposed on the surface facing the electrode 20 disposed surface of the electronic component 1 so that the electrodes 120 and 20 are aligned. Go and place. Then, as shown in FIG. 5B, the bump 130 provided on the electrode 120 of the electronic component 100 and the bonding layer 30 provided on the electrode 20 of the electronic component 1 are brought into contact with each other. Heating is performed at a melting temperature and a temperature lower than the melting point of the bump 130. Heating is performed in an inert gas atmosphere such as nitrogen (N ₂ ). Thereby, the bonding layer 30 on the electronic component 1 side and the bump 130 on the electronic component 100 side are bonded. At that time, the bonding layer 30 and the bump 130 are bonded as follows.

  In this example, the first layer 31 of the bonding layer 30 is eutectic Sn-Bi solder, and the second layer 32 on the first layer 31 is non-eutectic Sn-Bi solder. Here, first, the Bi composition of the Sn—Bi solder of the second layer 32 is smaller than the Bi composition (57 wt%) of the eutectic Sn—Bi solder (when Bi poor), and as an example, FIG. A case where the Bi composition of 21 wt% indicated by the line O1 in the state diagram of FIG.

  In this case, when the bonding layer 30 and the bump 130 are brought into contact with each other as shown in FIG. 5B and heated, the first of the bonding layer 30 is obtained up to the eutectic point (139 ° C.) from the state diagram of FIG. Both the layer 31 and the second layer 32 are in a solid phase (α + β) state. When the temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition contained in the first layer 31 melts and enters the liquid phase (L) from the state diagram of FIG.

  The Bi of the Sn—Bi solder of the first layer 31 thus in the liquid phase is diffused into the Sn—Bi solder of the second layer 32 having a smaller Bi composition than the Sn—Bi solder of the first layer 31. The Sn composition of the Sn—Bi solder of the second layer 32 is larger than the eutectic composition of the Sn—Bi solder of the first layer 31 (79 wt% in this example), and Sn from the Sn—Bi solder of the first layer 31 is larger. The diffusion of is suppressed. Sn of the Sn—Bi solder of the second layer 32 can diffuse into the Sn—Bi solder of the first layer 31 having a smaller Sn composition.

  The original Sn—Bi solder of the second layer 32 before Bi diffuses from the Sn—Bi solder of the first layer 31 in the liquid phase state is Sn—Bi having a non-eutectic composition with a Bi composition of 21 wt%. The melting point (liquidus temperature) of the solder is a temperature T1 above the eutectic point from the state diagram of FIG.

  When Bi diffuses from the Sn-Bi solder of the first layer 31 that has been in a liquid phase state by heating to the Sn-Bi solder of the second layer 32, the Sn-Bi solder of the second layer 32 becomes Bi. The composition increases and its melting point decreases from the temperature T1 so as to approach the eutectic point. For example, the portion of the Sn-Bi solder of the second layer 32 that comes into contact with the Sn-Bi solder of the first layer 31 in the liquid phase has a eutectic composition or a composition close thereto, and its melting point becomes the eutectic point. Decreases as you approach. Due to such a change in composition and a decrease in melting point, the melting of the Sn—Bi solder of the second layer 32 proceeds. If Sn of the Sn-Bi solder of the second layer 32 diffuses into the Sn-Bi solder of the first layer 31 having a smaller Sn composition, the change to a composition that lowers the melting point of the Sn-Bi solder of the second layer 32 Is more likely to occur. Between the melted Sn—Bi solder of the second layer 32 and the bumps 130, Sn or Bi is also diffused.

  The Sn—Bi solder of the second layer 32 is made of Sn in the first layer 31 due to the change in composition and the melting point as described above due to element diffusion with the Sn—Bi solder in the liquid phase state of the first layer 31. Melt almost simultaneously with the -Bi solder or continuously with the Sn-Bi solder of the first layer 31. Thereby, the 1st layer 31 and the 2nd layer 32 fuse and unite. Further, as the first layer 31 and the second layer 32 are melted and integrated, diffusion of elements such as Sn and Bi also proceeds between the bumps 130, and the components of the bumps 130, the first layer 31 and the second layer 32 are promoted. As shown in FIG. 5C, a solder joint 130a is formed. The melting of the first layer 31 and the second layer 32 and the integration of the bump 130 and the first layer 31 and the second layer 32 proceed promptly from the time when the eutectic point is reached. It becomes possible to suppress a constricted shape.

Thus, the electronic device 2 in which the electronic component 1 and the electronic component 100 are joined by the solder joint portion 130a is obtained.
Subsequently, the Bi composition of the Sn-Bi solder of the second layer 32 is larger than the Bi composition (57 wt%) of the eutectic Sn-Bi solder (when Bi rich), as an example of FIG. A case where the Bi composition of 75 wt% indicated by the line O2 in the state diagram is described.

  Also in this case, as shown in FIG. 5B, when the bonding layer 30 and the bump 130 are brought into contact with each other and heating is performed, the state of the bonding layer 30 is increased up to the eutectic point (139 ° C.) from the state diagram of FIG. Both the first layer 31 and the second layer 32 are in a solid phase (α + β) state. When the temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition contained in the first layer 31 melts and enters the liquid phase (L) from the state diagram of FIG.

  The Sn-Bi solder Sn in the first layer 31 thus in the liquid phase is diffused into the Sn-Bi solder in the second layer 32 having a smaller Sn composition than the Sn-Bi solder in the first layer 31. The Bi composition of the Sn—Bi solder of the second layer 32 is larger than the eutectic composition of the Sn—Bi solder of the first layer 31 (75 wt% in this example), and Bi from the Sn—Bi solder of the first layer 31 is larger. The diffusion of is suppressed. Bi of the Sn—Bi solder of the second layer 32 can diffuse into the Sn—Bi solder of the first layer 31 having a smaller Bi composition.

  The original Sn—Bi solder of the second layer 32 is a Sn—Bi solder having a non-eutectic composition with an Sn composition of 25 wt%, and its melting point (liquidus temperature) is the same as the state diagram of FIG. The temperature T2 is above the crystal point.

  When Sn diffuses from the Sn-Bi solder of the first layer 31 into the Sn-Bi solder of the second layer 32, the Sn composition of the Sn-Bi solder of the second layer 32 increases, and the melting point thereof increases. The temperature decreases from the temperature T2 so as to approach the eutectic point. For example, the portion of the Sn-Bi solder of the second layer 32 that comes into contact with the Sn-Bi solder of the first layer 31 in the liquid phase has a eutectic composition or a composition close thereto, and its melting point becomes the eutectic point. Decreases as you approach. Due to such a change in composition and a decrease in melting point, the melting of the Sn—Bi solder of the second layer 32 proceeds. Between the melted Sn—Bi solder of the second layer 32 and the bumps 130, Sn or Bi is also diffused. A composition that lowers the melting point of the Sn-Bi solder of the second layer 32 if the Bi of the Sn-Bi solder of the second layer 32 diffuses into the Sn-Bi solder or the bump 130 of the first layer 31 having a smaller Bi composition. The change to is more likely to occur.

  The Sn—Bi solder of the second layer 32 is made of Sn in the first layer 31 due to the change in composition and the melting point as described above due to element diffusion with the Sn—Bi solder in the liquid phase state of the first layer 31. Melt almost simultaneously with the -Bi solder or continuously with the Sn-Bi solder of the first layer 31. Thereby, the 1st layer 31 and the 2nd layer 32 fuse and unite. Further, as the first layer 31 and the second layer 32 are melted and integrated, diffusion of elements such as Sn and Bi also proceeds between the bumps 130, and the components of the bumps 130, the first layer 31 and the second layer 32 are promoted. As shown in FIG. 5C, a solder joint 130a is formed. The melting of the first layer 31 and the second layer 32 and the integration of the bump 130 and the first layer 31 and the second layer 32 proceed promptly from the time when the eutectic point is reached. It becomes possible to suppress a constricted shape.

Thus, the electronic device 2 in which the electronic component 1 and the electronic component 100 are joined by the solder joint portion 130a is obtained.
As described above, the bonding layer 30 of the electronic component 1 includes, for example, a Sn-Bi solder having a eutectic composition in the first layer 31 and a Bi composition smaller or larger than the Bi composition in the eutectic composition. The structure is a Sn—Bi solder having a non-eutectic composition. Thereby, melting of the eutectic Sn-Bi solder of the first layer 31, element diffusion between the molten Sn—Bi solder and the non-eutectic Sn—Bi solder of the second layer 32, etc. The melting point of the Sn—Bi solder of the second layer 32 is lowered due to the diffusion. Then, the solder joint portion 130a including the components of the bump 130, the first layer 31, and the second layer 32 is formed.

According to the bonding layer 30 described above, the bump 130 is at a temperature lower than its melting point and at or near the eutectic point of the Sn—Bi solder or the melting point of the Sn—Bi solder of the original second layer 32. It is possible to bond at a low temperature. The temperatures at which the bumps 130 are bonded to the bonding layer 30 are eutectic points of Sn—Bi solder having a eutectic composition provided as the first layer 31 of the bonding layer 30 and non-eutectic crystals provided as the second layer 32 of the bonding layer 30. It can set based on melting | fusing point of Sn-Bi solder of a composition. In manufacturing, in order to suppress the occurrence of bonding failure due to insufficient heating of the bump 130 and the bonding layer 30, the bonding temperature is a temperature lower than the melting point of the bump 130, and the eutectic of Sn—Bi solder of the bonding layer 30. For example, the temperature is set higher by about 10 ° C. to 40 ° C. than the point. For example, during manufacturing, the bonding temperature between the bump 130 and the bonding layer 30 is set to 160 ° C. In the bonding layer 30 described above, since the bonding temperature can be relatively low, an increase in power consumption at the time of bonding is suppressed, and an increase in carbon dioxide (CO ₂ ) emissions accompanying an increase in power consumption is suppressed. Is possible.

  The Bi composition of the non-eutectic Sn—Bi solder provided as the second layer 32 of the bonding layer 30 is 21 wt% to the composition range in which the solidus temperature of the Sn—Bi solder indicates the eutectic point. A range of 99.9 wt% is desirable.

  When the Bi composition of the Sn-Bi solder of the second layer 32 is less than 21 wt%, it is more than 99.9 wt% when the bump 130 and the bonding layer 30 are bonded from the state diagram of FIG. However, there is a possibility that the Sn—Bi solder of the second layer 32 remains as a solid phase (α or β). In this case, the effect of lowering the melting point of the Sn—Bi solder of the second layer 32 as described above cannot be sufficiently obtained, and the Sn—Bi solder of the first layer 31 and the second layer 32 is not melted and integrated. Can happen. As a result, a good crystalline solder joint cannot be obtained, and desired mechanical characteristics and joint reliability may not be obtained.

  On the other hand, when the Bi composition of the Sn—Bi solder of the second layer 32 is in the range of 21 wt% to 99.9 wt%, the liquid phase (L) appears from the eutectic point in the Sn—Bi solder. Therefore, element diffusion as described above is likely to occur between the Sn-Bi solder of the first layer 31 that is in a liquid phase at the eutectic point, and the melting point of the Sn-Bi solder of the second layer 32 is lowered. The integration of the first layer 31 with the Sn—Bi solder and the bump 130 is likely to occur. As a result, it is possible to obtain a solder joint having good crystallinity and excellent mechanical properties and joint reliability.

  From such a viewpoint, the Bi composition of the Sn—Bi solder of the second layer 32 is a composition range in which the solidus temperature indicates the eutectic point of the Sn—Bi solder of the eutectic composition used for the first layer 31. % To 99.9 wt% is desirable. In the case of Sn—Bi solder, the Sn composition of the non-eutectic Sn—Bi solder is 0.1 wt% to 79 wt%, which is the composition range in which the solidus temperature of the Sn—Bi solder indicates the eutectic point. It can also be said that it is desirable to set it in the range of%.

  As described above, here, on the electrode 20 of the electronic component 1, the first layer 31 including the eutectic Sn—Bi solder and the second layer 32 including the non-eutectic Sn—Bi solder are stacked. A bonding layer 30 having a structure is provided. The Sn-Bi solder of the eutectic composition of the first layer 31 of such a bonding layer 30 is melted at a temperature lower than its original melting point, the Sn-Bi solder of the non-eutectic composition of the second layer 32, The Sn-Bi solder of the first layer 31 and the second layer 32 and the bump 130 can be integrated. As a result, the bump 130 can be bonded to the bonding layer 30 at a temperature lower than the melting point of the bump 130 provided on the electronic component 100 to be bonded and at a relatively low temperature close to or equal to the eutectic point. Furthermore, the composition of the solder joint portion 130a of the electronic component 1 and the electronic component 100 can be adjusted by the non-eutectic composition Sn—Bi solder of the second layer 32 of the joining layer 30.

  As an example, FIG. 6 shows changes in mechanical properties due to the addition of Bi to Sn—Ag solder. FIG. 6 shows the relationship between Bi addition amount, tensile strength and elongation when Bi is added to Sn-Ag solder containing 1 wt% Ag. In FIG. 6, the horizontal axis represents Bi addition amount [wt%], and the vertical axis represents tensile strength [MPa] (left) and elongation [%] (right). From FIG. 6, the tensile strength of Sn-Ag solder (Ag; 1 wt%) shows a high value when the Bi addition amount is 5 wt% to 25 wt%, and the elongation is high when the Bi addition amount is 45 wt% to 65 wt%. Indicates the value.

  Based on the knowledge of FIG. 6, for example, when the bump 130 is Sn—Ag solder (Ag; 1 wt%), the Bi composition of the solder joint portion 130 a obtained by joining the bump 130 to the joining layer 30 is 5 wt% to 25 wt%. For example, the second layer 32 on the first layer 31 containing the Sn—Bi solder having the eutectic composition so that the solder joint portion 130a has such a Bi composition of 5 wt% to 25 wt% is included in the non-coincidence included therein. The Bi composition of the Sn—Bi solder having a crystal composition is adjusted. By using such a second layer 32, the Bi composition of the solder joint 130a in which the bump 130, the first layer 31, and the second layer 32 are integrated is set to 5 wt% to 25 wt%. By setting the Bi composition of the solder joint portion 130a to 5 wt% to 25 wt%, the electronic component 1 and the electronic component 100 can be joined by the solder joint portion 130a having high tensile strength.

  Further, based on the knowledge of FIG. 6, for example, when the bump 130 is Sn—Ag solder (Ag; 1 wt%), Bi of the solder joint portion 130 a obtained by joining the bump 130 to the joining layer 30. The composition is 45 wt% to 65 wt%. For example, the second layer 32 on the first layer 31 containing the Sn—Bi solder having the eutectic composition so that the solder joint portion 130a has such a Bi composition of 45 wt% to 65 wt% is included in the non-coincidence included therein. The Bi composition of the Sn—Bi solder having a crystal composition is adjusted. By using such a second layer 32, the Bi composition of the solder joint 130a in which the bump 130, the first layer 31, and the second layer 32 are integrated is set to 45 wt% to 65 wt%. By setting the Bi composition of the solder joint portion 130a to 45 wt% to 65 wt%, the electronic component 1 and the electronic component 100 can be joined by the solder joint portion 130a having a large elongation (high ductility).

  Here, for comparison, FIG. 7 shows an electronic component joining method according to another embodiment. FIG. 7A is a schematic cross-sectional view of an essential part showing an example of a state before joining electronic components, and FIG. 7B is a schematic cross-sectional view of an essential part showing an example of a state after joining electronic components.

  For example, as shown in FIG. 7A, a bonding layer 1030 containing a Sn—Bi solder having a eutectic composition is provided on the electrode 1020 of the electronic component 1000, and this is provided on the electrode 1120 of the other electronic component 1100. It is assumed that the Sn-Ag solder bump 1130 provided is bonded. Such an electronic component 1000 and the electronic component 1100 are aligned and arranged to face each other, the bonding layer 1030 and the bump 1130 are brought into contact with each other, and they are bonded by heating. For example, the bonding temperature is set to be equal to or higher than the melting point (eutectic point) of the Sn—Bi solder of the eutectic composition of the bonding layer 1030 and lower than the melting point of the Sn—Ag solder of the bump 1130. After the bonding layer 1030 and the bump 1130 are brought into contact with each other, the solder bonding portion 1130a formed from the bonding layer 1030 and the bump 1130 is formed as shown in FIG. 7B, for example, by heating at a predetermined bonding temperature. To do.

When eutectic Sn—Bi solder is used for the bonding layer 1030 as in this example, for example, Sn diffuses from the bump 1130 into the bonding layer 1030 during bonding, and the Sn—Bi solder composition is eutectic. It will shift from. As a result, the desired mechanical properties such as tensile strength and elongation cannot be obtained, and the life of the solder joint 1130a may be shortened. In consideration of diffusion of an element (for example, Sn) from the bump 1130, if a non-eutectic Sn—Bi solder (for example, Sn poor Sn—Bi solder) is used for the bonding layer 1030, the melting point of the bonding layer 1030 increases. (FIG. 2). Therefore, it is necessary to set the bonding temperature to be at least equal to or higher than the melting point of the non-eutectic Sn—Bi solder of the bonding layer 1030. If the bonding temperature is set to a temperature sufficiently higher than the melting point of Sn—Bi solder (for example, 200 ° C. or more), stress is likely to be generated in the solder joint 1130a, and the reliability of the solder joint 1130a may be reduced. . In addition, as shown in FIG. 7B, the solder joint portion 1130a may have a shape constricted between the joint layer 1030 and the bump 1130, and stress may concentrate on such a constricted portion, resulting in breakage. is there. Furthermore, as a result of the increase in the junction temperature, the power consumption at the time of the junction increases and the CO ₂ emission amount increases.

  On the other hand, in the bonding layer 30 of the electronic component 1, the second layer 32 including the non-eutectic Sn—Bi solder is provided on the first layer 31 including the eutectic Sn—Bi solder. At the time of bonding to the bump 130 of the electronic component 100 that is the bonding partner, the Sn—Bi solder of the first layer 31 is melted at the eutectic point, and the eutectic is caused by element diffusion from the first layer 31 and the melting point decrease thereby. The Sn-Bi solder of the second layer 32 is melted at or near a point. For this reason, even if Sn—Bi solder having a non-eutectic composition is used, it is not necessary to significantly increase the bonding temperature from the eutectic point.

  In the bonding layer 30 of the electronic component 1, the eutectic composition Sn—Bi solder of the first layer 31 is melted, the non-eutectic composition Sn—Bi solder of the second layer 32 is melted, the bump 130, the first layer 31. Integration of the layer 31 and the second layer 32 proceeds rapidly, and the constriction of the solder joint portion 130a is suppressed. Further, by adjusting the Bi composition of the non-eutectic Sn—Bi solder of the second layer 32, the Bi of the solder joint 130a in which the bump 130, the first layer 31, and the second layer 32 are integrated. The composition can be adjusted. Therefore, it is possible to obtain a solder joint portion 130a having desired mechanical characteristics according to the Bi composition and having excellent joint reliability.

The joining of electronic components using the joining layer 30 as described above includes joining of two electronic components and joining of three or more electronic components.
FIG. 8 illustrates an example of an electronic device. FIG. 8 schematically illustrates a cross-section of the main part of an example of the electronic device.

  An electronic device 2a illustrated in FIG. 8 includes an electronic component 1 and two electronic components 100 (in this case, an electronic component 100a and an electronic component 100b) bonded to the electronic component 1 via a solder joint 130a. ). The two electronic components 100 (100a, 100b) may be of the same type or different types. The electronic device 2a is obtained by bonding the bonding layer 30 provided on the electrode 20 of the electronic component 1 and the bump 130 provided on the electrode 120 of each electronic component 100 (100a, 100b). It is also possible to obtain an electronic device 2a including such three or more electronic components 1, 100a, 100b.

  Moreover, in such an electronic device 2a, by adjusting the Bi composition of the non-eutectic Sn—Bi solder provided as the second layer 32 in the bonding layer 30 of the electronic component 1 before bonding, Mechanical properties such as tensile strength and elongation of the solder joint 130a can be adjusted.

  In this case, for example, the solder joint 130a between the electronic component 1 and the electronic component 100a in the frame X in FIG. 8 and the solder joint 130a between the electronic component 1 and the electronic component 100b in the frame Y are 5 wt% to 25 wt%. Or a Bi composition of 45 wt% to 65 wt%. As a result, an electronic device 2a in which the electronic component 1, the electronic component 100a, and the electronic component 100b are joined by the solder joint portion 130a having a high tensile strength, or the electronic device 2a in which the solder joint portion 130a having a large elongation is joined is obtained. Can do.

  In addition, for example, the solder joint 130a between the electronic component 1 and the electronic component 100a in the frame X in FIG. 8 has a Bi composition of 5 wt% to 25 wt%, and the solder joint between the electronic component 1 and the electronic component 100b in the frame Y. 130a may be a Bi composition of 45 wt% to 65 wt%. Thus, the electronic device 2a can be obtained in which the electronic component 1 and the electronic component 100a are joined by the solder joint portion 130a having a high tensile strength, and the electronic component 1 and the electronic component 100b are joined by the solder joint portion 130a having a large elongation. it can.

  Further, for example, among the solder joint portions 130a of the electronic component 1 and the electronic component 100a, the solder joint portion 130a in the frame Z1 in FIG. The Bi composition may be 45 wt% to 65 wt%. As a result, it is possible to obtain the electronic device 2a in which the electronic component 1 and the electronic component 100a are joined by the solder joint portion 130a having a high tensile strength and the solder joint portion 130a having a large elongation. The same applies to the solder joint portion 130a between the electronic component 1 and the electronic component 100b.

  The Bi composition is adjusted for each of a plurality of solder joints based on the combination of electronic parts to be joined, the relationship of the joining positions of electronic parts, the use of an electronic device obtained by joining electronic parts, etc. It is possible to adjust the Bi composition of the previous bonding layer 30.

Next, a second embodiment will be described.
FIG. 9 is a diagram illustrating an example of an electronic component according to the second embodiment. FIG. 9 schematically illustrates a cross-section of an essential part of an example of an electronic component according to the second embodiment.

  The electronic component 1A illustrated in FIG. 9 has the electronic component according to the first embodiment in that the second layer 32 of the bonding layer 30 provided on the electrode 20 is a plurality of layers (here, two layers as an example). 1 and different.

  The second layer 32 of the exemplified electronic component 1A includes a solder layer 32a and a solder layer 32b containing Sn—Bi solder having a non-eutectic composition. The non-eutectic composition differs between the solder layer 32a on the electrode 20 side (first layer 31 side) and the solder layer 32b on the side to which the bump of the electronic component to be bonded (for example, the bump 130 of the electronic component 100) is bonded. Sn-Bi solder.

  For example, for the solder layer 32a on the first layer 31 containing the eutectic Sn-Bi solder, Sn-Bi solder having a smaller Bi composition (a larger Sn composition) than the eutectic Sn-Bi solder is used. . For the solder layer 32b on the solder layer 32a, Sn-Bi solder having a smaller Bi composition (large Sn composition) than the solder layer 32a is used. That is, the bonding layer 30 is formed such that the Bi composition gradually decreases from the electrode 20 side toward the bonded bump side.

  Alternatively, Sn—Bi solder having a larger Bi composition (smaller Sn composition) than the Sn—Bi solder having the eutectic composition is used for the solder layer 32a on the first layer 31 containing the Sn—Bi solder having the eutectic composition. For the solder layer 32b on the solder layer 32a, Sn-Bi solder having a larger Bi composition (smaller Sn composition) than that of the solder layer 32a is used. That is, the bonding layer 30 has a Bi composition that gradually increases from the electrode 20 side toward the bonded bump side.

  In the bonding layer 30 including the solder layer 32a and the solder layer 32b, the first layer 31 is formed on the electrode 20 according to the printing method shown in FIG. 3 and the plating method shown in FIG. The solder layer 32a and the solder layer 32b of the second layer 32 can be formed in order. In order to form the bonding layer 30 including the solder layer 32a and the solder layer 32b, a sputtering method, a vapor deposition method, and a dipping method can be used in addition to a printing method and a plating method.

  Even when the bonding layer 30 including the solder layer 32a and the solder layer 32b is used, the bumps on the other side are bonded as in the first embodiment. That is, when the bonding temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition of the first layer 31 on the electrode 20 side is first melted. Then, the Sn-Bi solder of the solder layer 32a is melted due to a decrease in melting point due to element diffusion between the Sn-Bi solder of the first layer 31 and the Sn-Bi solder of the solder layer 32a of the second layer 32. . Furthermore, the Sn—Bi solder of the solder layer 32b is melted due to the lowering of the melting point due to element diffusion between the Sn—Bi solder of the solder layer 32a and the Sn—Bi solder of the solder layer 32b. Thus, the 1st layer 31, the 2nd layer 32, and the bump on the other party are unified, and the solder joint part containing those components is formed.

Also with the electronic component 1A according to the second embodiment, it is possible to obtain an electronic device including a solder joint having desired mechanical characteristics and excellent joint reliability.
When the Bi composition of the Sn—Bi solder of the second layer 32 of the single layer is adjusted based on the Bi composition required for the solder joint, the Bi of the Sn—Bi solder of the first layer 31 depends on the Bi composition. The difference from the composition (melting point difference) is large, and there is a possibility that the melting point is lowered during melting and the melting does not proceed rapidly. In the bonding layer 30 of the electronic component 1A, the Bi composition is changed step by step to reduce the difference in the Bi composition between layers, so that the melting point of the solder layer 32a and the solder layer 32b is further lowered and melted quickly, and the solder layer It is also possible to adjust the Bi composition of the joint with high accuracy.

Next, a third embodiment will be described.
FIG. 10 is a diagram illustrating an example of an electronic component according to the third embodiment. FIG. 10 schematically illustrates a cross section of an essential part of an example of an electronic component according to the third embodiment.

  In the electronic component 1B illustrated in FIG. 10, a second layer 32 containing a non-eutectic composition Sn—Bi solder is provided on the electrode 20, and the second layer 32 contains a eutectic composition Sn—Bi solder. A bonding layer 30 provided with one layer 31 is provided. For the second layer 32, Sn-Bi solder having a smaller Bi composition (Bi poor) or a larger Bi composition (Bi rich) than the Bi composition of the eutectic Sn-Bi solder of the first layer 31 is used. In this respect, the electronic component 1B according to the third embodiment is different from the electronic component 1 according to the first embodiment.

  Such a bonding layer 30 is formed by forming the second layer 32 on the electrode 20 and forming the first layer 31 thereon in accordance with the printing method shown in FIG. 3 and the plating method shown in FIG. And you can get it. In addition to the printing method and the plating method, the bonding layer 30 can be formed by sputtering, vapor deposition, or dipping.

  In this way, the bonding layer 30 in which the second layer 32 and the first layer 31 are sequentially laminated on the electrode 20 and the bump on the other side are bonded as follows. That is, when the bonding temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition of the first layer 31 on the bump side on the second layer 32 is first melted. Then, element diffusion between the Sn—Bi solder of the first layer 31 and the Sn—Bi solder of the second layer 32, the bump of the bonding partner, the Sn—Bi solder of the first layer 31, and the second layer 32. The Sn—Bi solder of the second layer 32 melts due to the lowering of the melting point due to element diffusion with the Sn—Bi solder. Thus, the 1st layer 31, the 2nd layer 32, and the bump on the other party are unified, and the solder joint part containing those components is formed.

Also with the electronic component 1B according to the third embodiment, it is possible to obtain an electronic device including a solder joint having desired mechanical characteristics and excellent joint reliability.
In the bonding layer 30 of the electronic component 1B, for example, when a heating source is disposed on the electronic component 1 side when the bump is bonded, the first layer 31 closer to the bump reaches the eutectic point due to temperature distribution. At that time, it is easy to obtain a situation in which the second layer 32 on the electrode 20 closer to the heat source has already reached the eutectic point. Therefore, the melting of the Sn—Bi solder of the second layer 32 following the melting of the Sn—Bi solder of the first layer 31 proceeds promptly.

Next, a fourth embodiment will be described.
FIG. 11 is a diagram illustrating an example of an electronic component according to the fourth embodiment. FIG. 11 schematically illustrates a cross-section of an essential part of an example of an electronic component according to the fourth embodiment.

An electronic component 1C illustrated in FIG. 11 is different from the electronic component 1B according to the third embodiment in that the second layer 32 on the electrode 20 has a plurality of layers (here, two layers as an example).
The second layer 32 of the exemplified electronic component 1C includes a solder layer 32a and a solder layer 32b containing Sn—Bi solder having different non-eutectic compositions.

  For example, an Sn-Bi solder having a smaller Bi composition than the eutectic Sn-Bi solder is used for the solder layer 32a on the first layer 31 side including the eutectic Sn-Bi solder, and the solder layer on the electrode 20 side is used. The Sn-Bi solder having a smaller Bi composition than the solder layer 32a is used for 32b. That is, the bonding layer 30 has a Bi composition that gradually decreases from the bump side to be bonded to the electrode 20 side.

  Alternatively, a Sn-Bi solder having a larger Bi composition than the eutectic Sn-Bi solder is used for the first layer 31-side solder layer 32a containing the eutectic Sn-Bi solder, and the solder layer on the electrode 20 side is used. The Sn-Bi solder having a larger Bi composition than the solder layer 32a is used for 32b. That is, the bonding layer 30 has a Bi composition that gradually increases from the bonded bump side toward the electrode 20 side.

  Such a bonding layer 30 is formed by sequentially forming the solder layer 32b and the solder layer 32a of the second layer 32 on the electrode 20 in accordance with the printing method shown in FIG. 3 and the plating method shown in FIG. It can be obtained by forming the first layer 31. In addition to the printing method and the plating method, the bonding layer 30 can be formed by sputtering, vapor deposition, or dipping.

  Such bonding between the bonding layer 30 and the mating bump is performed as follows. That is, when the bonding temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition of the first layer 31 on the bump side is first melted. Then, element diffusion between the Sn-Bi solder of the first layer 31 and the Sn-Bi solder of the solder layer 32a, the bumps of the bonding partner, and the Sn-Bi solder of the first layer 31 and the Sn-Bi of the solder layer 32a. The Sn—Bi solder of the solder layer 32a is melted due to the lowering of the melting point due to element diffusion with the solder. Further, the element diffusion between the Sn-Bi solders of the solder layer 32a and the solder layer 32b, the bumps to be joined and the Sn-Bi solder of the first layer 31 and the solder layer 32a, and the Sn-Bi solder of the solder layer 32b. The Sn—Bi solder of the solder layer 32b melts due to the lowering of the melting point due to the element diffusion. Thus, the 1st layer 31, the 2nd layer 32, and the bump on the other party are unified, and the solder joint part containing those components is formed.

Also with the electronic component 1 </ b> C according to the fourth embodiment, it is possible to obtain an electronic device including a solder joint portion having desired mechanical characteristics and excellent joint reliability.
In addition, in the bonding layer 30 of the electronic component 1C according to the fourth embodiment, the Bi composition is changed stepwise to reduce the difference in the Bi composition between the layers, and the melting point of the solder layer 32a and the solder layer 32b is lowered and melted. Can be advanced promptly, and the Bi composition of the solder joint can be accurately adjusted.

  Further, in the bonding layer 30 of the electronic component 1 </ b> C, when a heat source is arranged on the electronic component 1 side and heated when bonding the bumps, the Sn of the second layer 32 following the melting of the Sn—Bi solder of the first layer 31. -The melting of Bi solder can be rapidly advanced.

Next, a fifth embodiment will be described.
FIG. 12 is a diagram illustrating an example of an electronic component according to the fifth embodiment. FIG. 12 schematically shows a cross section of an essential part of an example of an electronic component according to the fifth embodiment.

  An electronic component 1D illustrated in FIG. 12 includes a bonding layer 30 including a second layer 32 on the electrode 20, a first layer 31 on the second layer 32, and a third layer 33 on the first layer 31. This is different from the electronic component 1B according to the third embodiment. Similar to the electronic component 1B, the second layer 32 includes a non-eutectic Sn-Bi solder, and the first layer 31 on the second layer 32 includes a eutectic Sn-Bi solder. The third layer 33 of the electronic component 1D according to the fifth embodiment includes a non-eutectic Sn—Bi solder. For the second layer 32 and the third layer 33, Sn-Bi solder having a smaller Bi composition or larger Bi composition than the Bi composition of Sn-Bi solder having the eutectic composition of the first layer 31 can be used.

  Such a bonding layer 30 is formed by forming the second layer 32 on the electrode 20 and the first layer 31 on the electrode 20 in accordance with the printing method shown in FIG. 3 and the plating method shown in FIG. Furthermore, it can be obtained by forming the third layer 33 thereon. In addition to the printing method and the plating method, the bonding layer 30 can be formed by sputtering, vapor deposition, or dipping.

  Such bonding between the bonding layer 30 and the mating bump is performed as follows. That is, when the bonding temperature reaches the eutectic point, the Sn—Bi solder having the eutectic composition of the first layer 31 between the second layer 32 and the third layer 33 is first melted. Then, due to a decrease in melting point due to element diffusion between the Sn—Bi solder of the first layer 31 and the Sn—Bi solder of the second layer 32 and the third layer 33, the second layer 32 and the third layer 33 Sn-Bi solder melts. Thus, the 1st layer 31, the 2nd layer 32, the 3rd layer 33, and the other party bump are unified, and the solder joint part containing those components is formed.

Also with the electronic component 1D according to the fifth embodiment, it is possible to obtain an electronic device including a solder joint having desired mechanical characteristics and excellent joint reliability.
Further, in the bonding layer 30 of the electronic component 1D, when heating is performed by arranging a heat source on the electronic component 1 side at the time of bonding the bump, the Sn of the second layer 32 following the melting of the Sn—Bi solder of the first layer 31 is performed. -The melting of Bi solder can be rapidly advanced.

  Further, in the bonding layer 30 of the electronic component 1D, a third layer 33 is provided in addition to the second layer 32, and the Bi composition of the Sn-Bi solder is adjusted, thereby accurately adjusting the Bi composition of the solder bonding portion. can do.

  The second layer 32 of the electronic component 1D according to the fifth embodiment has a plurality of Bi compositions that are changed stepwise in accordance with the example of the second layer 32 of the electronic component 1C according to the fourth embodiment. It is also possible to have a laminated structure of solder layers.

  Further, the third layer 33 of the electronic component 1D according to the fifth embodiment has the Bi composition changed stepwise in accordance with the example of the second layer 32 of the electronic component 1A according to the second embodiment. A laminated structure of a plurality of solder layers can also be used.

Next, a sixth embodiment will be described.
In the electronic component 1, 1A, 1B, 1C, 1D as described above, bumps of other electronic components (the bumps 130 of the electronic component 100) can be bonded, as well as solder balls or the like. Single bumps can also be joined.

  FIG. 13 is a diagram illustrating an example of a method of forming an electronic component according to the sixth embodiment. 13A is a schematic cross-sectional view of an essential part showing an example of a state before bump bonding, FIG. 13B is a schematic cross-sectional view of an essential part showing an example of a bump bonding process, and FIG. 13C is a view after bump bonding. It is a principal part cross-sectional schematic diagram which shows an example of a state.

  Here, the electronic component 1 according to the first embodiment will be described as an example. First, as shown in FIG. 13A, an electronic component 1 having a bonding layer 30 provided on the electrode 20 of the component body 10 and a bump 130 using Sn-based solder are prepared. And this bump 130 is arrange | positioned on the joining layer 30 of the electronic component 1 as shown in FIG.13 (B). From this state, for example, heating is performed at a temperature lower than the melting point of the bump 130 at a eutectic point of Sn-Bi solder or a temperature equivalent thereto. As a result, the components of the bump 130, the first layer 31, and the second layer 32 are caused by melting of the Sn—Bi solder of the first layer 31 and the second layer 32 and diffusion of elements such as Sn and Bi between the bumps 130. The contained terminal 130b as shown in FIG. 13C is formed. In this way, the electronic component 1 having the terminal 130b can also be obtained.

Here, the electronic component 1 is taken as an example, but the other electronic components 1A, 1B, 1C, and 1D can be similarly formed with such terminals 130b.
In the above description, the case where Sn—Bi solder is used as the solder used for the bonding layer 30 is taken as an example. In addition to Sn—Bi solder, Sn—Ag solder, Sn—Zn solder, Sn—In solder is used. Sn-Pb solder or the like can also be used. Even when such solder is used, the bonding layer 30 can be formed by the above-described method (FIG. 3, FIG. 4, etc.), and bonding with bumps of other electronic components or single bumps is possible. (FIG. 5, FIG. 13, etc.) can be performed.

  Various electronic components can be used for the electronic components described above (electronic components 1, 1A, 1B, 1C, 1D, and electronic component 100). For example, as described above, a circuit board, a semiconductor element, or a semiconductor device can be used for the electronic component.

FIG. 14 is a diagram illustrating an example of a circuit board. FIG. 14 schematically illustrates a cross section of an essential part of an example of a circuit board.
Here, a multilayer printed board including a plurality of wiring layers is taken as an example of the circuit board. A circuit board 200 illustrated in FIG. 14 includes a conductor portion 210 (wiring and via) and an insulating portion 220 that covers the conductor portion 210. Various conductor materials such as Cu and Al are used for the conductor portion 210. For the insulating portion 220, a resin material such as a phenol resin, an epoxy resin, or a polyimide resin, a composite resin material in which such a resin material is impregnated into glass fiber or carbon fiber, or the like is used. The circuit board 200 is provided with an electrode 211 (corresponding to the electrode 20 or the electrode 120 described above) that is electrically connected to the internal conductor portion 210. Various bonding layers 30 as described above or bumps 130 are provided on such an electrode 211 to obtain an electronic component.

FIG. 15 is a diagram illustrating an example of a semiconductor element. FIG. 15 schematically illustrates a cross section of a main part of an example of a semiconductor element.
A semiconductor element 300 illustrated in FIG. 15 includes a semiconductor substrate 310 provided with an element such as a transistor, and a wiring layer 320 provided on the semiconductor substrate 310.

  As the semiconductor substrate 310, a substrate such as silicon (Si), germanium (Ge), or silicon germanium (SiGe) is used. Such a semiconductor substrate 310 is provided with elements such as a transistor, a capacitor, and a resistor. FIG. 15 shows a MOS (Metal Oxide Semiconductor) transistor 330 as an example of the element.

  The MOS transistor 330 is provided in an element region defined by an element isolation region 310 a provided in the semiconductor substrate 310. The MOS transistor 330 has a gate electrode 332 formed on the semiconductor substrate 310 via a gate insulating film 331, and a source region 333 and a drain region 334 formed in the semiconductor substrate 310 on both sides of the gate electrode 332. An insulating film spacer 335 is provided on the side wall of the gate electrode 332.

  A wiring layer 320 is provided on the semiconductor substrate 310 provided with such a MOS transistor 330 and the like. The wiring layer 320 includes a conductor portion 321 (wiring and via) that is electrically connected to the MOS transistor 330 and the like provided on the semiconductor substrate 310, and an insulating portion 322 that covers the conductor portion 321. As an example, FIG. 15 illustrates a conductor portion 321 electrically connected to the source region 333 and the drain region 334 of the MOS transistor 330. Various conductor materials such as Cu and Al are used for the conductor portion 321. For the insulating portion 322, an inorganic insulating material such as silicon oxide or an organic insulating material such as resin is used. The wiring layer 320 is provided with an electrode 323 (corresponding to the electrode 20 or the electrode 120 described above) that is electrically connected to the internal conductor portion 321. Various bonding layers 30 as described above or bumps 130 are provided on such an electrode 323 to obtain an electronic component.

FIG. 16 illustrates an example of a semiconductor device. FIG. 16 schematically illustrates a cross section of a main part of an example of the semiconductor device.
A semiconductor device 400 illustrated in FIG. 16 includes a package substrate (circuit substrate) 500, a semiconductor element 600 mounted on the package substrate 500, and a sealing layer 700 that seals the semiconductor element 600.

  For example, a printed circuit board is used as the package substrate 500. The package substrate 500 includes a conductor portion 510 (wiring and via) such as Cu and Al, and an insulating portion 520 such as a resin material that covers the conductor portion 510.

  On such a package substrate 500, the semiconductor element 600 is electrically connected (flip chip bonding) with a connecting portion 610 such as a solder bump provided thereon. An underfill resin 710 is filled between the package substrate 500 and the semiconductor element 600. The semiconductor element 600 on the package substrate 500 is sealed with a sealing layer 700. For the sealing layer 700, a resin material such as an epoxy resin, a material obtained by adding an insulating filler to such a resin material, or the like is used. On the surface of the package substrate 500 opposite to the mounting surface of the semiconductor element 600, an electrode 511 (corresponding to the electrode 20 or the electrode 120 described above) electrically connected to the internal conductor portion 510 is provided. Various bonding layers 30 as described above or bumps 130 are provided on such an electrode 511 to obtain an electronic component.

  The semiconductor element 600 may be electrically connected to the package substrate 500 by wire bonding. Furthermore, a plurality of semiconductor elements 600 may be mounted on the package substrate 500, and in addition to the semiconductor elements 600, other electronic components such as chip capacitors may be mounted.

Examples and comparative examples are shown below.
[Example 1]
The planar size is 8.5 mm × 8.5 mm, and about 120 Sn-3Ag-0.5Cu solder (Ag; 3 wt%, Cu; 0.5 wt%) solder bumps are arranged on the outer periphery of the one surface. A semiconductor element was prepared. Also, a printed board (glass epoxy board) having a plane size of 40 mm × 40 mm and having Cu electrodes at positions corresponding to the solder bumps of the semiconductor element was prepared.

  A solder paste containing eutectic Sn-57Bi solder (Sn; 57 wt%) was provided on the electrodes of the prepared printed circuit board by screen printing. Furthermore, a solder paste containing non-eutectic Sn-21Bi solder (Sn; 21 wt%) was provided on the solder paste by screen printing. As a result, a bonding layer having a structure in which a solder paste containing Sn-57Bi solder and a solder paste containing Sn-21Bi solder were laminated was obtained.

The prepared semiconductor element was mounted on a printed circuit board provided with such a bonding layer by aligning the electrodes of the printed circuit board with the solder bumps of the semiconductor element using a chip mounter. Then, a heated N ₂ atmosphere, was joined with the bonding layer on the printed circuit board electrodes, and a solder bump of the semiconductor element. The preheating conditions at the time of joining were a temperature of 100 ° C. to 120 ° C. and a time of 90 seconds to 120 seconds, and the peak conditions were a temperature of 160 ° C. and a time of 50 seconds to 60 seconds. The cooling rate was 2 ° C./second to 3 ° C./second. Thus, a semiconductor device was obtained in which the printed circuit board and the semiconductor element were joined at the solder joint including the joining layer and the solder bump components.

  As a result of conducting a continuity test of the solder joint using the lead wiring on the printed circuit board side of the obtained semiconductor device, it was confirmed that all the solder joints were conducted. Furthermore, as a result of a drop impact test in which the drop height was 1.6 m and the substrate distortion amount was 4000 με and this was repeated for 40 cycles, the connection resistance change rate was + 5% or less. As a result of cross-sectional SEM (Scanning Electron Microscopy) / EPMA (Electron Probe MicroAnalysis) analysis of the solder joint, the Bi composition of the solder joint is 10 wt%, and the solder joint is a cause of deterioration due to drop impact. It was confirmed that there was no confinement.

[Example 2]
A solder paste containing Sn-57Bi solder and a solder paste containing Sn-75Bi solder (Sn; 75 wt%) were sequentially laminated on the electrode of the printed circuit board described in Example 1 to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 60 wt% and the solder joint was not constricted.

Example 3
A solder paste containing Sn-57Bi solder, a solder paste containing Sn-45Bi solder (Sn; 45 wt%), and a solder paste containing Sn-21Bi solder are sequentially laminated on the electrodes of the printed circuit board described in Example 1. A bonding layer was obtained. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 20 wt% and the solder joint was not constricted.

Example 4
A solder paste containing Sn-21Bi solder and a solder paste containing Sn-57Bi solder were sequentially laminated on the electrodes of the printed circuit board described in Example 1 to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 10 wt% and the solder joint was not constricted.

Example 5
A solder paste containing Sn-75Bi solder and a solder paste containing Sn-57Bi solder were sequentially laminated on the electrode of the printed circuit board described in Example 1 to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 60 wt% and the solder joint was not constricted.

Example 6
A solder paste containing Sn-21Bi solder, a solder paste containing Sn-45Bi solder, and a solder paste containing Sn-57Bi solder were sequentially laminated on the electrode of the printed circuit board described in Example 1 to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 20 wt% and the solder joint was not constricted.

Example 7
A solder paste containing Sn-21Bi solder, a solder paste containing Sn-57Bi solder, and a solder paste containing Sn-75Bi solder were sequentially laminated on the electrode of the printed circuit board described in Example 1 to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the solder joint was not constricted.

Example 8
On the electrode of the printed circuit board described in Example 1, Sn-57Bi solder and Sn-21Bi solder were sequentially laminated by plating to form a bonding layer. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  It was confirmed by conduction tests of the solder joints of the obtained semiconductor device that all the solder joints were conducted. Furthermore, as a result of a 40-cycle drop impact test, the connection resistance change rate was + 5% or less. As a result of the cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 10 wt% and the solder joint was not constricted.

[Comparative Example 1]
A solder paste containing Sn-57Bi solder was formed as a bonding layer on the electrode of the printed circuit board described in Example 1. A semiconductor device in which a semiconductor element is mounted on a printed circuit board provided with such a bonding layer in the same manner as in the first embodiment, and the printed circuit board and the semiconductor element are bonded by a solder bonding portion including a bonding layer and a solder bump component. Got the device.

  As a result of performing a 10-cycle drop impact test on the obtained semiconductor device, the connection resistance change rate was + 50% or more. As a result of cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the Bi composition of the solder joint was 30 wt%, and that the solder joint was constricted and cracks were formed.

[Comparative Example 2]
A solder paste containing Sn-57Bi solder was formed as a bonding layer on the electrode of the printed circuit board described in Example 1. A semiconductor element is mounted on a printed circuit board provided with such a bonding layer with a peak temperature at the time of bonding of 200 ° C., and the printed circuit board and the semiconductor element are bonded to each other at a solder bonding portion including a bonding layer and a solder bump component. A semiconductor device was obtained.

  As a result of performing a 10-cycle drop impact test on the obtained semiconductor device, the connection resistance change rate was + 50% or more. As a result of cross-sectional SEM / EPMA analysis of the solder joint, it was confirmed that the solder joint partially contained Sn-rich Sn-Bi solder and cracks were formed.

Regarding the embodiment described above, the following additional notes are further disclosed.
(Supplementary note 1) a substrate having electrodes;
A bonding layer provided on the electrode, and
The bonding layer is
A first layer including a first solder containing a first element and a second element having a eutectic composition;
An electronic component comprising: a second layer that is laminated with the first layer and includes a second solder containing the first element and the second element having a non-eutectic composition.

(Additional remark 2) The said 1st element contains Sn, The electronic component of Additional remark 1 characterized by the above-mentioned.
(Additional remark 3) The said 2nd element contains Bi, The electronic component of Additional remark 2 characterized by the above-mentioned.
(Additional remark 4) Said 2nd solder contains said 1st element and said 2nd element of the composition range in which solidus temperature shows a eutectic point, The additional description 1 thru | or 3 characterized by the above-mentioned. Electronic components.

(Supplementary Note 5) The composition of the first element contained in the second solder is larger than the composition of the first element contained in the first solder.
The electronic component according to any one of appendices 1 to 4, wherein the composition of the second element contained in the second solder is smaller than the composition of the second element contained in the first solder. .

(Appendix 6) The bonding layer is
The second layer includes a third solder which is laminated on the opposite side of the first layer and includes the first element and the second element having a non-eutectic composition different from that of the second solder. Further comprising three layers,
The composition of the first element contained in the third solder is greater than the composition of the first element contained in the second solder,
The electronic component according to appendix 5, wherein the composition of the second element contained in the third solder is smaller than the composition of the second element contained in the second solder.

(Supplementary Note 7) The composition of the first element contained in the second solder is smaller than the composition of the first element contained in the first solder.
The electronic component according to any one of appendices 1 to 4, wherein a composition of the second element contained in the second solder is larger than a composition of the second element contained in the first solder. .

(Appendix 8) The bonding layer is
The second layer includes a third solder which is laminated on the opposite side of the first layer and includes the first element and the second element having a non-eutectic composition different from that of the second solder. Further comprising three layers,
The composition of the first element contained in the third solder is smaller than the composition of the first element contained in the second solder,
The electronic component according to appendix 7, wherein the composition of the second element contained in the third solder is larger than the composition of the second element contained in the second solder.

(Additional remark 9) The process of preparing the board | substrate which has an electrode,
Forming a bonding layer on the electrode, and
The step of providing the bonding layer includes:
Forming a first layer including a first solder containing a first element and a second element having a eutectic composition;
Forming a second layer including a second solder that is laminated with the first layer and contains the first element and the second element having a non-eutectic composition. Method.

(Additional remark 10) The manufacturing method of the electronic component of Additional remark 9 characterized by further including the process of joining to the said joining layer the bump | vamp of melting | fusing point higher than the liquidus temperature of the said 2nd solder.
(Additional remark 11) The board | substrate which has an electrode,
A bonding layer provided on the electrode, and
The bonding layer is
A first layer including a first solder containing a first element and a second element having a eutectic composition;
Providing a first electronic component having a second layer laminated with the first layer and including a second solder containing the first element and the second element having a non-eutectic composition;
Preparing a second electronic component having a bump having a melting point higher than that of the bonding layer;
And a step of melting the bonding layer at a temperature equal to or higher than a eutectic point of the first solder and lower than a liquidus temperature of the second solder, and bonding the bonding layer and the bump. Production method.

1, 1A, 1B, 1C, 1D, 100, 100a, 100b, 1000, 1100 Electronic component 2, 2a Electronic device 10, 110 Component body 10a, 110a Front surface 10b Back surface 20, 120, 211, 323, 511, 1020, 1120 Electrode 30, 1030 Bonding layer 31 First layer 32 Second layer 32a, 32b Solder layer 33 Third layer 40 First mask 41, 51, 61 Opening 50 Second mask 60 Resist 130, 1130 Bump 130a, 1130a Solder bonding portion 130b Terminal 200 Circuit board 210, 321, 510 Conductor portion 220, 322, 520 Insulating portion 300, 600 Semiconductor element 310 Semiconductor substrate 310a Element isolation region 320 Wiring layer 330 MOS transistor 331 Gate insulating film 332 Gate electrode 333 Source region 334 Rain region 335 spacer 400 semiconductor device 500 package substrate 610 connection portion 700 sealing layer 710 underfill resin O1, O2 line T1, T2 temperature P solidus Q liquidus X, Y, Z1, Z2 frame

Claims (5)

A substrate having electrodes;
A bonding layer provided on the electrode, and
The bonding layer is
A first layer including a first solder containing a first element and a second element having a eutectic composition;
A second layer including the second solder, which is laminated with the first layer and has a non-eutectic composition and a composition range in which a solidus temperature indicates a eutectic point, and contains the first element and the second element; An electronic component comprising: The composition of the first element contained in the second solder is greater than the composition of the first element contained in the first solder,
The composition of the second element contained a second solder, the electronic component according to claim 1, wherein less than the composition of the second element contained in the first solder. The composition of the first element contained in the second solder is smaller than the composition of the first element contained in the first solder,
The composition of the second element contained a second solder, the electronic component according to claim 1, wherein greater than the composition of the second element contained in the first solder. Preparing a substrate having electrodes;
Forming a bonding layer on the electrode, and
The step of providing the bonding layer includes:
Forming a first layer including a first solder containing a first element and a second element having a eutectic composition;
A second layer including a second solder, which is laminated with the first layer and has a non-eutectic composition and a composition range in which a solidus temperature shows a eutectic point and contains the first element and the second element; A process for forming the electronic component. A substrate having electrodes;
A bonding layer provided on the electrode, and
The bonding layer is
A first layer including a first solder containing a first element and a second element having a eutectic composition;
A second layer including the second solder, which is laminated with the first layer and has a non-eutectic composition and a composition range in which a solidus temperature indicates a eutectic point, and contains the first element and the second element; Preparing a first electronic component having:
Preparing a second electronic component having a bump having a melting point higher than that of the bonding layer;
And a step of melting the bonding layer at a temperature equal to or higher than a eutectic point of the first solder and lower than a liquidus temperature of the second solder, and bonding the bonding layer and the bump. Production method.

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