JP7000693B2 - Bonding structure and mounting structure of semiconductor devices and joining method - Google Patents

Description

The present invention relates to a joining structure for mounting a semiconductor device on a substrate, a mounting structure using the same, and a joining method, and more particularly to a joining structure, a mounting structure, and a joining method for relaxing stress applied to a joining portion.

A semiconductor device represented by a large-scale integrated circuit (Large Scale Integrated Circuit, hereinafter referred to as LSI) is usually mounted on a printed circuit board or the like and used. FIG. 12A shows a mounting structure 200 of a general semiconductor device. FIG. 12B is an explanatory diagram showing an LSI chip configuration of a general mounting structure. FIG. 12C is an explanatory diagram showing a board configuration of a general mounting structure. As shown in FIG. 12B, the LSI chip 1 has a plurality of LSI chip electrode pads 8. Further, as shown in FIG. 12C, the substrate 2 has a plurality of substrate electrode pads 9.

The LSI chip electrode pad 8 and the substrate electrode pad 9 are generally circular, and are joined by solder bumps 7 to form a joining structure 20. Note that FIGS. 12B and 12C show the center 21 of the LSI chip and the diagonal line 26. Further, FIG. 12C shows the outer circumference 27 of the LSI chip 1 joined by a rectangular broken line.

FIG. 13 shows a perspective view of a general joint structure 20. The solder bump 7 generally has a barrel shape (barrel shape). Note that FIG. 13 shows a broken line indicating the center direction 25 of the LSI chip. The LSI chip 1 is made of, for example, silicon, and the substrate 2 is made of, for example, resin or ceramics.

Here, when the mounting structure 200 itself generates heat or the device in which the mounting structure 200 is incorporated generates heat, stress is applied to the solder bump 7 due to the difference in the linear expansion coefficient between the LSI chip 1 and the substrate 2. Is added. The stress is concentrated on the circumference of the joint portion between the LSI chip electrode pad 8 and the solder bump 7 and the joint portion between the substrate electrode pad 9 and the solder bump 7. Further, the largest stress is generated along a straight line toward the center of the LSI chip 1 (center 21 of the LSI chip), particularly along a diagonal line from the corner of the LSI chip 1 toward the center.

In this way, in a general barrel-shaped solder bump, stress is concentrated on the joint between the electrode pad of the LSI chip or the substrate and the solder bump during the thermal cycle operation due to the difference in the coefficient of thermal expansion between the LSI chip and the substrate. , There is a problem that the reliability of the connection part is lowered.

Patent Documents 1 to 3 describe examples of the structure and arrangement of the electrode pads in the joint structure for relaxing the stress at the joint between the solder bump and the electrode pad.

In Patent Document 1, at least one outer periphery of the electrode pad has a first curved portion and a second curved portion, has a smaller curvature than the first curved portion, and has a tangent line at the center of the first curved portion. Discloses a joint structure provided at a position substantially perpendicular to a straight line toward the center of the first structure.

Patent Document 2 is a polyhedron in which an electrode pad has at least one side of a straight line, and the side of the one straight line is at a predetermined angle (preferably substantially orthogonal) with respect to a straight line toward the center of the first structure. ) Is disclosed.

Patent Document 3 discloses a joint structure in which lands close to the four corners of an interbosa substrate are formed into a square, and two sets of squares are parallel to and perpendicular to the diagonal line of the interbosa substrate. is doing. Further, Patent Document 3 discloses that two sets of opposite sides of each land are in a parallel and vertical relationship with respect to a line connecting the center of the interposer substrate and the center of the upper left and upper right lands.

In addition, Patent Document 4 discloses a method of joining a first substrate having a first electrode pad and a second substrate having a second electrode pad. Specifically, in Patent Document 4, one of the first substrate and the second substrate is rotated with respect to the other while the solder sandwiched between the first electrode pad and the second electrode pad is melted. Disclosed is a joining method in which one of the first electrode and the second electrode is joined by shifting them in parallel to the other.

Patent Document 5 discloses a method in which an LSI chip is pulled up with respect to a substrate when the solder pump is melted, and the solder pump is stretched into a drum shape.

Japanese Unexamined Patent Publication No. 2015-122457 Japanese Unexamined Patent Publication No. 2014-033020 Japanese Patent No. 5040746 Japanese Unexamined Patent Publication No. 2001-127202 Japanese Unexamined Patent Publication No. 10-223693

However, when the substrate is rotated and joined as in the joining method described in Patent Document 4, that is, when the first electrode pad and the second electrode pad are joined by shifting their positions, the stress concentration points are located. There was the problem of change.

Therefore, an object of the present invention is to provide a joining structure, a mounting structure, and a joining method capable of reducing the stress applied to the joining member when the electrode portions are joined to each other by using the joining member.

The joining structure according to the present invention includes a first component having a first electrode portion, a second component having a second electrode portion, and a joining member for joining the first electrode portion and the second electrode portion. The first electrode portion and the second electrode portion are joined in a state of being displaced from each other, and a part of the first electrode portion is provided at a position corresponding to the stress concentration portion applied to the joining member. The first electrode portion and the second electrode portion have one relaxation portion, and are rotated with respect to the other component with the center of one component, which is one of the first component or the second component, as the rotation axis. The first electrode portion is joined by a joining member, and the first electrode portion is composed of a first curved line or a first straight line in which a part of the first electrode portion has a smaller curvature than the other portions . The relaxation part is formed by a combination of the first curve or the second curve corresponding to the other part having a curvature larger than the first straight line, and the first electrode part forms the first part. It is characterized in that it is rotated and joined in the same direction as the second component.

The mounting structure according to the present invention is a mounting structure having the above-mentioned joining structure.

In the joining method according to the present invention, the first electrode portion of the first component and the second electrode portion of the second component, which are arranged at opposite positions, are joined by using a joining member, and at the time of joining. The first electrode portion and the second electrode portion having the relaxation portion at the position corresponding to the stress concentration portion applied to the joint member are centered on one component which is one of the first component or the second component. As a rotation axis, the first electrode portion and the second electrode portion are joined by a joining member in a state of being rotated with respect to the other component, and the first electrode portion is the first electrode portion of the first electrode portion. A relaxation part consisting of a first curve or a first straight line whose part has a smaller curvature than the other part, and a second curve corresponding to the first curve or another part having a larger curvature than the first straight line. It is formed in combination with and, and is characterized in that the first electrode portion is rotated and joined in the same direction as the first component is rotated with respect to the second component.

According to the present invention, when the electrode portions are joined to each other by using the joining member, the stress applied to the joining member can be reduced.

It is explanatory drawing which shows the example of the cross-sectional structure of the embodiment of the mounting structure by this invention. It is explanatory drawing which shows the structural example of the LSI chip of this embodiment. It is explanatory drawing which shows the substrate structure example of this embodiment. It is explanatory drawing which shows the structural example of the mounting structure of this embodiment. It is explanatory drawing which shows the example of the method of mounting an LSI chip on a board. It is a top view which shows the structural example of the joint structure of this embodiment. It is a perspective view which shows the structural example of the joint structure of this embodiment. It is explanatory drawing which shows the arrangement of the junction structure used in the stress distribution simulation. It is explanatory drawing which shows the result of the stress distribution simulation of the LSI chip electrode pad of the junction structure of this embodiment. It is explanatory drawing which shows the result of the stress distribution simulation of the substrate electrode pad of the bonding structure of this embodiment. It is explanatory drawing which shows the result of the stress distribution simulation of the LSI chip electrode pad of a general junction structure. It is explanatory drawing which shows the result of the stress distribution simulation of the substrate electrode pad of a general junction structure. It is explanatory drawing which shows the result of the stress distribution simulation of the LSI chip electrode pad of a general junction structure. It is explanatory drawing which shows the result of the stress distribution simulation of the substrate electrode pad of a general junction structure. It is explanatory drawing which shows the other result of the stress distribution simulation of the LSI chip electrode pad of a general junction structure. It is explanatory drawing which shows the other result of the stress distribution simulation of the substrate electrode pad of a general junction structure. It is a top view which shows the modification of the joint structure of this embodiment. It is a top view which shows the other modification of the joint structure of this embodiment. It is a block diagram which shows the outline of the junction structure by this invention. The mounting structure of a general semiconductor device is shown. It is explanatory drawing which shows the LSI chip structure of the general mounting structure. It is explanatory drawing which shows the board structure of a general mounting structure. It is a perspective view which shows the general joint structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, although the embodiments described below have technically preferable limitations for carrying out the present invention, the scope of the invention is not limited to the following.

1A to 1D are explanatory views showing an embodiment of the mounting structure 100 according to the present invention. Specifically, FIG. 1A is an explanatory diagram showing a cross-sectional configuration example of an embodiment of the mounting structure 100 according to the present invention. FIG. 1B is an explanatory diagram showing a configuration example of the LSI chip of the present embodiment. FIG. 1C is an explanatory diagram showing an example of a substrate configuration of the present embodiment. FIG. 1D is an explanatory diagram showing a configuration example of the mounting structure 100 of the present embodiment.

As shown in FIGS. 1A and 1B, the LSI chip 1 has a plurality of LSI chip electrode pads 3 and a plurality of LSI chip electrode pads 5. Further, as shown in FIGS. 1A and 1C, the substrate 2 has a plurality of substrate electrode pads 4 and a plurality of substrate electrode pads 6. In the present embodiment, the shape of the LSI chip electrode pad 3 and the substrate electrode pad 4 is a shape including a curved line or a straight line having a part having a smaller curvature than the other part. That is, the shapes of the LSI chip electrode pad 3 and the LSI chip electrode pad 5 are different. Similarly, the substrate electrode pad 4 and the substrate electrode pad 6 have different shapes.

In the examples shown in FIGS. 1B and 1C, pads having different shapes are arranged at the four corners of the LSI chip 1 and the four corners of the substrate 2, respectively. Further, in FIGS. 1B and 1C, the center 21 indicates the center position of the LSI chip 1. FIG. 1B shows the center 28 of the LSI chip electrode pad 3 and a part of the side of the LSI chip electrode pad 3 formed by a curved line or a straight line having a smaller curvature than the other portions (hereinafter referred to as LSI). The tangent line 30 with respect to the pad target side) is shown in the figure. The LSI chip 1 illustrated in FIG. 1B is rectangular. 1B and 1C show a diagonal line 26 connecting the vertices.

Further, FIG. 1C shows the center 29 of the substrate electrode pad 4. The broken line 31 is a tangent line to a part of the side of the substrate electrode pad 4 formed by a curved line or a straight line having a curvature smaller than that of the other portion (hereinafter, referred to as a substrate pad target side) in the substrate electrode pad 4. Further, FIG. 1C illustrates a line 33 connecting the center 21 of the LSI chip and the center 29 of the substrate electrode pad.

The shape of the LSI chip electrode pad 5 and the substrate electrode pad 6 may be a general circular shape. Further, similarly to the shapes of the LSI chip electrode pad 3 and the substrate electrode pad 4 described above, the shapes of the LSI chip electrode pad 5 and the substrate electrode pad 6 include a curve or a straight line whose curvature is partially smaller than that of the other portion. You may.

The LSI chip electrode pad 3 and the substrate electrode pad 4 are joined by a solder bump 7 (hereinafter, simply referred to as a bump 7) to form a joining structure 10 exemplified in FIG. 1A. Further, the LSI chip electrode pad 5 and the substrate electrode pad 6 are joined by a bump 7 to form the joining structure 11 illustrated in FIG. 1A.

The rectangular broken line exemplified in FIG. 1C shows the outer circumference 27 of the LSI chip when the LSI chip 1 is mounted on the substrate 2. FIG. 1D shows a state in which the LSI chip 1 is mounted on the substrate 2. As shown in FIG. 1D, the LSI chip electrode pad 3 and the substrate electrode pad 4 are joined by the solder pump 7 in a state of being displaced from each other.

Although FIGS. 1B and 1D show the LSI chip electrode pad 3 with a solid line, it actually shows a state in which the LSI chip electrode pad 3 is seen through from above the LSI chip.

The LSI chip electrode pads 3 and 5 and the substrate electrode pads 4 and 6 are made of a metal having excellent conductivity such as copper, and the surface thereof is coated with a film having excellent solder wettability, for example, gold or a solder alloy. Is formed. The bump 7 is, for example, general solder or lead-free solder. Further, the LSI chip 1 is mainly made of silicon, and the substrate 2 is mainly made of resin or ceramics.

The mounting structure 100 illustrated in FIG. 1A is manufactured, for example, by the following method.

Regarding the method of forming each electrode pad, for example, it is possible to form an electrode pad by photolithography and etching after forming a copper film to be an electrode by a plating method or the like. Further, for example, it is also possible to lift off the photoresist by embedding copper in the electrode portion by a plating method or the like after forming the frame of the electrode with the photoresist.

Further, after forming a solder bump on the electrode pad, the LSI chip and the substrate are aligned with each other, and further temperature control is performed to bond the electrode of the LSI chip and the electrode of the substrate via the solder bump. The chip can be mounted on the board.

FIG. 2 is an explanatory diagram showing an example of a method of mounting an LSI chip on a substrate. FIG. 2A is a mounting method seen from the upper part of the substrate 2, and FIG. 2B is a mounting method seen from the side surface of the board 2.

As shown in FIG. 2, in a state where the solder bump 7 is melted, the LSI chip 1 is sucked by, for example, a vacuum suction jig 51, and the LSI chip 1 is rotated around the center of the LSI chip 1 as a rotation axis. In this way, with the LSI chip 1 rotated, the solder bumps 7 are solidified and mounted on the substrate 2. As a result, the joining structure 10 of the present embodiment is formed.

The above-mentioned manufacturing method is an example, and may be manufactured by using, for example, the method described in Patent Document 4.

Next, the joining structure 10 of the present embodiment will be described with reference to FIGS. 3A and 3B. FIG. 3A is a top view showing a configuration example of the joint structure according to the embodiment of the present invention. FIG. 3B is a perspective view showing a configuration example of the joint structure according to the embodiment of the present invention.

In FIGS. 3A and 3B, a straight line toward the center direction 25 of the LSI chip is shown by a broken line. For example, when the LSI chip 1 is a quadrangular LSI chip as illustrated in FIG. 1B, this straight line includes a straight line along the diagonal line 26.

A part of the side (that is, the target side of the LSI pad) 23 of the LSI chip electrode pad 3 formed by a curve or a straight line having a smaller curvature than the other part is an LSI with respect to a straight line toward the center direction 25 of the LSI chip. It is arranged so as to have a predetermined angle in the same direction as the rotation direction of the chip. Here, when the target side of the LSI pad is a curve, the desired angle is an angle formed by the straight line toward the center direction 25 and the tangential direction of the curve. When the target side of the LSI pad is a straight line, the desired angle is an angle formed by the straight line toward the center direction 25 and the straight line. Further, a portion corresponding to the other portion of the LSI chip electrode pad 3 (that is, a curved portion having a large curvature) is arranged on the outer peripheral side of the LSI chip. In the following description, the target side of the LSI pad formed by the curve may be referred to as the first curved portion. Further, a portion corresponding to another portion of the LSI chip electrode pad 3 (that is, a curved portion having a large curvature) may be referred to as a second curved portion.

A part of the side (that is, the target side of the board pad) 24 of the substrate electrode pad 4 formed by a curve or a straight line having a smaller curvature than the other portion is the LSI chip with respect to the straight line toward the center direction 25 of the LSI chip. It is arranged so as to have a desired angle in the same direction as the rotation direction of the. Here, when the target side of the substrate pad is a curve, the desired angle is the angle formed by the straight line toward the center direction 25 and the tangential direction of the curve. When the target side of the substrate pad is a straight line, the predetermined angle is an angle formed by the straight line toward the center direction 25 and the straight line. Further, a portion corresponding to the other portion of the substrate electrode pad 4 (that is, a curved portion having a large curvature) is arranged on the center 21 side of the LSI chip. Similar to the above, in the following description, the target side of the substrate pad formed by the curve may be referred to as the first curved portion. Further, a portion corresponding to another portion of the substrate electrode pad 4 (that is, a curved portion having a large curvature) may be referred to as a second curved portion.

As described above, the LSI chip electrode pad 3 and the substrate electrode pad 4 are joined by a bump 7 to form a joining structure 10. The LSI pad target side 23 and the board pad target side 24 are opposite to the bump center 22 (or the center of the space) of the bump 7 that fills the space between the LSI chip electrode pad 3 and the board electrode pad 4. It can be said that it is on the side or in a position symmetrical to the point.

When the mounting structure 100 itself generates heat or the device in which the mounting structure 100 is incorporated generates heat, stress is applied to the bonded structure 10 due to the difference in the linear expansion coefficient between the LSI chip 1 and the substrate 2. The stress is concentrated on the joint portion between the LSI chip electrode pad 3 and the bump 7 and the joint portion between the substrate electrode pad 4 and the bump 7.

When the LSI chip is not rotating, the greatest stress is generated along a straight line toward the center of the LSI chip 1, particularly along a diagonal line 26 from the corner to the center of the LSI chip 1. On the other hand, when the LSI chip is rotating, the contact angle of the bump 7 becomes larger on the side opposite to the direction in which the LSI chip of the pad rotates, so that the largest stress is from the diagonal line 26 to the LSI chip. It occurs at a position deviated by a predetermined angle in the same direction as the rotation direction.

As described above, the shape of the LSI chip electrode pad 3 and the substrate electrode pad 4 is a shape having a curved line or a straight line having a part having a smaller curvature than the other part. For example, assume that the LSI chip 1 is a quadrangle as shown in FIG. 1B. In this case, the LSI chip electrode pad 3, the substrate electrode pad 4, and the bonding structure 10 including the solder bump 7 are at least four located on the outermost circumference on the diagonal line 26, which is the farthest from the center of the LSI chip 1. It will be implemented in at least one of them. The joining structure at other points may be implemented by the general joining structure 20.

However, the place where the joining structure 10 is mounted is not limited to one. The largest stress is generated along the diagonal line 26 from the corner of the LSI chip 1 toward the center, and the stress becomes larger toward the outer circumference thereof. Therefore, it is more effective to use the joint structure 10 of the present embodiment as the joint structure of the outer peripheral portion in order to relieve the stress. The joining structure 10 is not limited to the outer peripheral portion. It is effective to relieve stress even if all of the joint structures are the joint structure 10 of the present embodiment and the joint structure at an arbitrary position is the joint structure 10 of the present embodiment.

Further, in the present embodiment, as the shape of the LSI chip electrode pad 3 and the substrate electrode pad 4, a shape including a perfect circular arc is exemplified. However, if at least one side of these electrode pads is a polyhedron having a curved line or a straight line having a smaller curvature than the other part, an elliptical arc may be included. Even with such a shape, it has the effect of reducing the maximum stress in the stress distribution.

Further, in the present embodiment, a quadrangle is exemplified as the shape of the LSI chip. However, the shape of the LSI chip is not limited to a quadrangle. The shape of the LSI chip can be any polygon, circle, or ellipse. At this time, the electrodes of the junction structure of the present embodiment are arranged so that the LSI pad target side and the substrate pad target side have a predetermined angle in the same direction as the rotation direction of the LSI chip with respect to the straight line toward the center of the LSI chip. do it. As described above, when the target side of the LSI pad and the target side of the substrate pad are curved lines, the desired angle is the angle formed by the tangential direction of the curve and the straight line toward the center of the LSI chip. When the LSI pad target side and the substrate pad target side are straight lines, the predetermined angle is the angle formed by the straight line and the straight line toward the center of the LSI chip. By arranging in this way, it becomes possible to relieve the stress inside the joint structure.

As described above, the joint structure 10 of the present embodiment can alleviate the stress concentration on the joint portion between the bump and the electrode pad during a thermal cycle or the like. In particular, in the bonding structure 10 of the present embodiment, the LSI chip is rotated at the time of soldering so that the solder bumps are stretched toward the outside. In this way, the stress generated by deviating from the straight line toward the center of the LSI chip where the largest stress is generated in the same direction as the rotation direction of the LSI chip can be relaxed.

Further, the bonding structure 10 of the present embodiment does not require a special LSI chip or a mounting device having a mechanism for precisely holding the height between the substrates as described in Patent Document 5. Therefore, the joined structure of the present embodiment and the mounting structure using the joined structure can be obtained by a simple method.

Next, an example in which the stress distribution generated at this joint is calculated by simulation is shown. As the stress, Mises stress representing the stress value projected onto the uniaxial tensile or compressive stress was used in a stress field in which a load is applied in a complex manner from multiple directions. FIG. 4 shows the arrangement of the joining structure 12 used in the simulation. The bonding structure 12 is the bonding structure 10 of the present embodiment shown in FIG. 3B or the general bonding structure 20 shown in FIG. 13, and is bonded to the LSI chip and the substrate.

As shown in FIG. 4, 144 joint structures 12 are arranged 12 × 12. The stress distribution was calculated for the joint structure 12 based on this arrangement. Further, in FIG. 4, the joint structure X causes the largest stress. Therefore, the joining structure X is set to the joining structure 10 shown in FIG. 3B so that the calculation can be simplified and the effect of the joining structure 10 of the present embodiment can be remarkably confirmed on the general joining structure 20. Other than that, the normal joining structure 20 shown in FIG. 13 was used. Further, as a comparative example, a simulation was performed with the joint structure X as the joint structure 20 shown in FIG.

As the main calculation conditions, the linear expansion coefficient of the LSI chip is 3 ppm / ° C., the size is 26 mm × 26 mm, and the thickness is 1 mm. The linear expansion coefficient of the substrate is 32 ppm / ° C., the size is 56 mm × 56 mm, and the thickness is 1.6 mm. When the electrode pad is circular, the diameter is 0.5 mm, the bump height is 0.5 mm, and the temperature conditions are 25 ° C to 150 ° C. The stress distribution of the joint structure X that produces the largest stress is shown below.

FIG. 5A shows the stress distribution of the LSI chip electrode pad 3 in the junction structure 10 of the present embodiment. Further, FIG. 5B shows the stress distribution of the substrate electrode pad 4 in the bonding structure 10 of the present embodiment. In FIGS. 5A and 5B, the corners of each pad are rounded. This is because when the pad is actually manufactured, the corners are rounded due to the manufacturing process. Further, as a comparative example, with respect to the bonding structure 20 using a general circular electrode pad, the stress distribution of the LSI chip electrode pad 8 is shown in FIG. 6A, and the stress distribution of the substrate electrode pad 9 is shown in FIG. 6B.

Referring to FIGS. 5A and 5B, the stress distribution of the LSI chip electrode pad 3 and the substrate electrode pad 4 is the maximum stress on the outer peripheral portion of the pad deviated from the straight line toward the center direction 25 of the LSI chip in the rotational direction of the LSI chip. It can be seen that the distribution is such that In the LSI chip electrode pad 3, the maximum stress was 2188 MPa on the center side of the LSI chip, and in the substrate electrode pad 4, it was 2152 MPa on the outer peripheral side.

Referring to FIGS. 6A and 6B, even in the stress distribution of the circular LSI chip electrode pad 8 and the substrate electrode pad 9, if there is no rotation of the LSI chip, the outer circumference of the pad along the straight line toward the center direction 25 of the LSI chip. It can be seen that the distribution is such that the maximum stress is generated in the part. In the LSI chip electrode pad 8, the maximum stress was 2620 MPa on the center side of the LSI chip, and in the substrate electrode pad 9, it was 1981 MPa on the outer peripheral side.

FIG. 7A is an explanatory diagram showing the result of stress distribution simulation of the LSI chip electrode pad 8 when the LSI chip is rotated by the general junction structure 20. Further, FIG. 7B is an explanatory diagram showing the result of stress distribution simulation of the substrate electrode pad 9 when the LSI chip is rotated by the general bonding structure 20.

Referring to FIGS. 7A and 7B, when the LSI chip is rotated, the stress distribution of the circular LSI chip electrode pad 8 and the substrate electrode pad 9 is from the straight line toward the center direction 25 of the LSI chip to the rotation direction of the LSI chip. It can be seen that the distribution is such that the maximum stress is generated on the outer peripheral portion of the displaced pad. The maximum stress was 2338 MPa on the LSI center side in the LSI chip electrode pad 8 and 2442 MPa on the outer peripheral side in the substrate electrode pad 9.

FIG. 8A is an explanatory diagram showing the result of stress distribution simulation of the LSI chip electrode pad 8 when the LSI chip is rotated in the general junction structure 20 and the electrode pad is not rotated. Further, FIG. 8B is an explanatory diagram showing the result of stress distribution simulation of the substrate electrode pad 9 when the LSI chip is rotated by the general bonding structure 20 and the electrode pad is not rotated.

A case where the LSI chip is rotated but the electrode pad is not rotated will be described with reference to FIGS. 8A and 8B. In this case, in the stress distribution of the LSI chip electrode pad 8 and the substrate electrode pad 9, the same distribution as in the case of a shape having a curve or a straight line having a part having a smaller curvature than the other part is observed. That is, in the stress distribution of the LSI chip electrode pad 8 and the substrate electrode pad 9, the maximum stress is generated in the outer peripheral portion of the pad deviated from the straight line toward the center direction 25 of the LSI chip in the rotation direction of the LSI chip. I understand. In the LSI chip electrode pad 8, the maximum stress was 2309 MPa on the center side of the LSI chip, and in the substrate electrode pad 9, it was 2466 MPa on the outer peripheral side.

Based on the stress distribution simulation results shown above, the maximum stress values are compared below. The joining structure with a pad having a curved or straight line in which the LSI chip is rotated during soldering and one part has a smaller curvature than the other part is different from the joining structure with a circular pad when the LSI chip is not rotated during soldering. , The maximum stress value was reduced by 16.4% on the center side of the LSI chip electrode pad.

At the time of soldering, the LSI chip is rotated around the center of the LSI chip as the rotation axis, and the solder bumps are stretched toward the outside from the center. , Or a shape having a straight line. Then, the electrode pad is rotated and installed in the same direction as the rotation direction of the LSI chip, and the bonding structure 10 shown in FIGS. 3A and 3B is formed. By doing so, it was clarified that the stress inside the joint structure can be reduced.

As described above, in the present embodiment, a relaxation portion such as the LSI pad target side 23 is provided at a position corresponding to the portion (stress concentration portion) where the stress applied to the solder pump 7 is concentrated on a part of the LSI chip electrode pad 3. It is provided. Therefore, when the electrode portions are joined to each other by using the joining member, the stress applied to the joining member can be reduced.

A curve in which a part of the circular pad has a smaller curvature than the other part or a curve in which the part where the maximum stress occurs has a smaller curvature than the other part as the cause of the decrease in the maximum stress in the stress distribution of the pad having a shape having a straight line. Alternatively, the fact that it is a straight line means that the stress is dispersed.

That is, when the LSI chip is rotated during soldering, the maximum stress is generated at a position deviated from the center direction of the LSI chip in the rotation direction of the LSI chip. In the present embodiment, the LSI pad target side 23 of the LSI chip electrode pad 3 is arranged in a direction deviated from the vertical direction in the rotation direction of the LSI chip in the tangent line to the center direction of the LSI chip.

Therefore, since the stress is dispersed on the side having a small curvature or the side of a straight line, the stress can be reduced. On the other hand, in the circular pad, the stress is concentrated at a position deviated from the center direction of the LSI chip in the rotation direction of the LSI chip along the curve of a perfect circular arc having a larger curvature, so that the stress increases.

In the LSI chip electrode pad 3 and the substrate electrode pad 4, whether the LSI pad target side 23 and the substrate pad target side 24 should be arranged on the center side or the outer peripheral side of the LSI chip depends on the thickness and size of the LSI chip and the substrate. It depends on the size and so on.

When the rigidity of the substrate is higher than that of the LSI chip because the thickness of the substrate is larger than that of the LSI chip, the dimensions are larger, or the Young's modulus is larger, the stress on the center side of the LSI chip 1 is applied in the LSI chip electrode pad 3. growing. In such a case, as shown in FIGS. 3A and 3B, the LSI pad target side 23 is arranged on the center side, and the side having a large curvature is arranged on the outer peripheral side.

On the contrary, in the substrate electrode pad 4, the stress on the outer peripheral side increases corresponding to the LSI chip electrode pad 3, so that the substrate pad target side 24 is arranged on the outer peripheral side as shown in FIGS. 3A and 3B, and the curvature is increased. Place the large side on the center side.

By adopting the joint structure 10 having such a configuration, stress distribution is effectively performed by the side of a curved line or a straight line having a curvature smaller than that of other portions on the side where the stress is large. In addition, the original stress is small on the side with a large curvature. Therefore, as shown in FIGS. 5A and 5B, a stress distribution having a smaller maximum stress than a circular pad can be realized by a pad having a curved shape or a straight line in which a part has a curvature smaller than that of the other part.

When the rigidity of the LSI chip is higher than that of the substrate, the arrangement of the LSI chip electrode pad 3 and the substrate electrode pad 4 in the bonding structure 10 of the present embodiment can be reversed from the arrangement shown in FIGS. 3A and 3B. That is, the LSI pad target side has a predetermined angle in the same direction as the rotation direction of the LSI chip with respect to the straight line toward the center direction of the LSI chip, and is arranged on the outer peripheral side of the LSI chip. On the other hand, the target side of the substrate pad has a predetermined angle in the same direction as the rotation direction of the LSI chip with respect to the straight line toward the center direction of the LSI chip, and is arranged on the center side of the LSI chip.

Next, a modified example of the joining structure of the present embodiment will be described. FIG. 9 is a top view showing a modified example of the joint structure of the present embodiment.

As shown in FIG. 9, the LSI chip electrode pad 32 and the substrate electrode pad 42 may have a shape in which a part has a curve or a straight line having a curvature opposite to that of the other part. That is, the side 53 of the LSI chip electrode pad 32 is a curve having a curvature opposite to that of the other portion. Further, the side 54 of the substrate electrode pad 42 is a curved line having a curvature opposite to that of the other portion. Even in the bonded structure 13 in which the LSI chip electrode pad 32 and the substrate electrode pad 42 and the bump 72 are combined, the stress is dispersed by a curve having a curvature opposite to that of the other portions, so that the maximum stress can be reduced. can.

Further, the LSI chip electrode pad and the substrate electrode pad do not necessarily have to have the same shape, dimensions, and the same polyhedron. That is, an LSI chip electrode pad and a substrate electrode pad having different shapes may be joined by bumps to form a joining structure.

Further, FIG. 10 is a top view showing another modified example of the joining structure of the present embodiment. As shown in FIG. 10, the LSI chip electrode pad 32 and the substrate electrode pad 4 may have a shape in which a part has a curve or a straight line having a curvature opposite to that of the other part. That is, the side 53 of the LSI chip electrode pad 32 is a curve having a curvature opposite to that of the other portion. Further, the side 24 of the substrate electrode pad 4 is a side having a curve or a straight line having a curvature opposite to that of the other portion. Even in the bonded structure 14 in which the LSI chip electrode pad 32 and the substrate electrode pad 4 and the bump 73 are combined, the stress is dispersed in a curved or straight portion having a curvature opposite to that of the other portions, so that the maximum stress is reduced. be able to.

Further, contrary to the example shown in FIG. 10, that is, the side 23 of the LSI chip electrode pad 3 is a side having a curve or a straight line having a curvature opposite to that of the other portion, and the side 54 of the substrate electrode pad 42 is another. It may be a curve having a curvature opposite to that of the portion of.

Furthermore, the shape of the electrode pad having a curved or straight line whose curvature is partially smaller than that of the other part, or the shape of the electrode pad to be combined up and down with the electrode pad having a curve having a curvature opposite to the other part is optional. be. These electrode pads can also be any polygon composed of straight lines such as triangles, quadrangles, pentagons and octagons.

Further, the shape of these electrode pads may be not only a polygon but also a polyhedron having a straight line on one side. For example, there is a polyhedron shape in which one side is a straight line and the other side is a curved line. With such a shape, stress can be dispersed in a straight line portion as in the case where a part has a side having a smaller curvature than the other part.

In the case of these examples, in order to reduce the stress inside the junction structure, the length of one side of the electrode pad arranged at a predetermined angle in the same direction as the rotation direction of the LSI chip from the center direction of the LSI chip is set. It is desirable to make it as long as possible to help disperse the stress.

Further, in the above, in FIGS. 1A to 1D and FIGS. 3A to 3B, the LSI pad target side 23 and the board pad target side 24 are the bump centers of bumps that fill the space between the LSI chip electrode pad 3 and the board electrode pad 4. It was explained that the 22 can be arranged on the opposite side or in a position symmetrical with respect to a point. Further, in the above, the LSI pad target side 23 and the board pad target side 24 can be arranged on opposite sides or substantially point-symmetrically with respect to the center of the space between the LSI chip electrode pad 3 and the board electrode pad 4. Explained.

On the other hand, depending on the stress distribution state, it is assumed that the stress on either the LSI chip side or the substrate side is lower than that on the other side. In this case, the electrode pad with the lower stress is placed on the opposite side of the electrode pad to which the curved or straight side having a smaller curvature than the other part joins or at a position symmetrical to the point point to disperse the stress. There is no need. These electrode pads may be arranged in the same direction.

As described above, in the present embodiment, the bonding structure 10 includes an LSI chip 1 having an LSI chip electrode pad 3, a substrate 2 having a substrate electrode pad 4, and a solder pump 7 for bonding these electrode pads. There is. Then, the solder pump 7 joins the LSI chip electrode pad 3 and the substrate electrode pad 4 in a state of being displaced from each other. Further, a part of the LSI chip electrode pad 3 has an LSI pad target side 23 as a relaxation portion at a position corresponding to the stress concentration portion applied to the solder pump 7. Therefore, the stress applied to the solder pump 7 can be reduced.

For example, in the methods described in Patent Document 1 and Patent Document 2, the LSI chip does not rotate with respect to the substrate. On the other hand, in the present invention, the LSI electrode pad and the substrate electrode pad are displaced (for example, in the horizontal direction in FIG. 3A). As a result, the solder pump is stretched and the stress concentration on the solder pump is relaxed.

Further, in the case of the methods described in Patent Document 1 and Patent Document 2, the effect of relaxing stress concentration cannot be obtained unless the LSI electrode pad and the substrate electrode pad are perpendicular to each other. On the other hand, in the present invention, the stress concentration points are displaced due to the rotation of the LSI chip. If this angle remains vertical, the effect of relieving stress cannot be obtained, so it is arranged at a predetermined angle (for example, about 30 degrees) from the center of the pad in the same direction as the rotation direction of the LSI chip from the vertical. .. That is, in the present invention, the pad is rotated and arranged in the direction in which the stress concentration is deviated so as not to impair the effect of rotating the LSI chip and stretching the solder pump to relieve the stress.

Next, the outline of the present invention will be described. FIG. 11 is a block diagram showing an outline of the joining structure according to the present invention. The bonding structure according to the present invention comprises a first component 80 (for example, an LSI chip 1) having a first electrode portion 81 (for example, an LSI chip electrode pad 3) and a second electrode portion 71 (for example, a substrate electrode pad). A second component 70 (for example, a substrate electrode pad 6) having 4) and a joining member 91 (for example, a solder bump 7) for joining the first electrode portion 81 and the second electrode portion 71 are provided. ..

The joining member 91 joins the first electrode portion 81 and the second electrode portion 71 in a state of being displaced from each other, and a position corresponding to a part of the first electrode portion 81 corresponding to the stress concentration portion applied to the joining member 91. It has a relaxation unit 82 (for example, an LSI pad target side 23).

With such a configuration, when the electrode portions are joined to each other by using the joining member, the stress applied to the joining member can be reduced.

The relaxation portion 82 may be a first curved portion having a radius of curvature different from that of the other portions of the first electrode portion 81. Further, the relaxation portion 82 may have a substantially linear shape.

Further, the first electrode portion may have a second curved portion having a radius of curvature larger than the shape of the relaxation portion 82.

Further, the relaxation portion 82 may be provided so as to face the center side of the first component 80 and the second curved portion to face the outside of the first component 80. The second electrode portion 71 has the shape of the relaxation portion 82 and the second curved portion, the second curved portion faces the center side of the first component 80, and the relaxation portion 82 having the above shape has the shape of the relaxation portion 82. , May be provided so as to face the outside of the first component 80.

Further, by shifting the positions of the first component 80 or the second component 70, the positions of the first electrode portion 81 and the second electrode portion 71 may be shifted and joined.

Specifically, by rotating and joining the first component 80 or the second component 70, the positions of the first electrode portion 81 and the second electrode portion 71 may be shifted and joined.

Further, the first electrode portion 81 and the second electrode portion 71 are rotated with respect to the other component with the center of one component of the first component 80 or the second component 70 as the rotation axis. The space may be joined by the joining member 91. Further, the relaxation portion 82 of the first electrode portion 81 has a first curved line or a first straight line (for example, the LSI pad target side 23) in which a part of the first electrode portion 81 has a smaller curvature than the other portions. And may be formed in combination with the second curve. Then, in the first electrode portion 81, the tangent line or the first straight line of the first curve with respect to the second straight line toward the center of the first component 80 is the same as the rotation direction of the first component 80. It may be arranged at a predetermined angle in the direction.

On the other hand, the relaxation portion 82 may be formed with a curve having a curvature opposite to that of the other portions of the first electrode portion 81.

Further, the first electrode portion of the first component and the second electrode portion of the second component may be provided at opposite positions.

Further, the mounting structure of the present invention (for example, the mounting structure 100) has the above-mentioned joining structure of the present invention (for example, the joining structure 10).

The joining structure of the present invention can also be described as follows.
The joining structure of the present invention is a joining structure (for example, joining structure 10) for joining a first structure (for example, LSI chip 1) and a second structure (for example, a substrate 2), and the joining is described above. The structure includes a first electrode pad (for example, LSI chip electrode pad 3) bonded to the first structure and a second electrode pad (for example, a substrate electrode pad 4) bonded to the second structure. The first electrode pad has a bump (for example, a solder pump 7) to be joined to the second electrode pad, and the first structure is a first structure at the time of joining to the second structure. The first structure is rotated with respect to the second structure with the center of the (for example, the center 28 of the LSI chip electrode pad) as the center of rotation, and the shape is stretched so that the joint structure goes outward. It is a joint structure that is joined up to. Further, the pitch of the first electrode pad and the pitch of the second electrode pad are the same, and the first electrode pad and the second electrode pad facing each other via the joint structure are mutually exclusive. It is displaced in parallel, and the deviation between the first electrode pad and the second electrode pad increases as the distance from the center of the first structure or the second structure increases. The deviation between the first electrode pad and the second electrode pad located at the farthest position from the center is within one of the first electrode pad, the second electrode, or the bonded structure. Is.

The shape of the first electrode pad and the second electrode pad may be a curved line or a straight line having a part having a smaller curvature than the other part.

In addition, some or all of the above embodiments may be described as in the following appendix, but are not limited to the following.

(Appendix 1) A first component having a first electrode portion, a second component having a second electrode portion, and a joining member for joining the first electrode portion and the second electrode portion. The joining member is provided with the first electrode portion and the second electrode portion joined in a state of being displaced from each other, and a part of the first electrode portion corresponds to a stress concentration portion applied to the joining member. A joint structure characterized by having a relaxation portion at a position where the stress is formed.

(Appendix 2) The joining structure according to Appendix 1, wherein the relaxation portion is a first curved portion having a radius of curvature different from that of the other portion of the first electrode portion.

(Appendix 3) The relaxation portion has a substantially linear shape and has a joining structure according to the appendix 1.

(Appendix 4) The joint structure according to Appendix 2 or Appendix 3, wherein the first electrode portion has a second curved portion having a radius of curvature larger than the shape of the relaxation portion.

(Appendix 5) The relaxation portion is provided so as to face the center side of the first component, the second curved portion faces the outside of the first component, and the second electrode portion faces the outside of the first component. It has the shape of the relaxation portion and the second curved portion, the second curved portion faces the center side of the first component, and the relaxation portion of the shape faces the outside of the first component. The joint structure according to Appendix 4, which is provided as described above.

(Appendix 6) Of Appendix 1 to Appendix 5, the first electrode portion and the second electrode portion are joined by shifting the positions of the first component or the second component by shifting the positions of the first electrode portion and the second electrode portion. The bonding structure according to any one.

(Supplementary Note 7) The joining according to Supplementary Note 6, wherein the first component or the second component is rotated and joined to shift the positions of the first electrode portion and the second electrode portion. Construction.

(Appendix 8) The first electrode portion and the second electrode portion in a state of being rotated with respect to the other component with the center of one component of the first component or the second component as a rotation axis. The relaxation portion of the first electrode portion is joined to the first curved line or the first straight line in which a part of the first electrode portion has a smaller curvature than the other portion. , The first electrode portion is formed by a tangent line of the first curve or the first straight line to the second straight line toward the center of the first component. The joining structure according to any one of Supplementary note 1 to Supplementary note 7, which is arranged at a predetermined angle in the same direction as the rotation direction of the first component.

(Supplementary note 9) The joint structure according to Supplementary note 1, wherein the relaxation portion is formed by a curve having a curvature opposite to that of the other portion of the first electrode portion.

(Appendix 10) The first electrode portion of the first component and the second electrode portion of the second component are provided at opposite positions, and any one of Supplementary note 1 to Supplementary note 9 is provided. The joint structure described in 1.

(Appendix 11) A mounting structure having a bonding structure according to any one of Supplementary note 1 to Supplementary note 10.

(Appendix 12) The first electrode portion of the first component and the second electrode portion of the second component, which are arranged at opposite positions, are joined by using a joining member. The first electrode portion having a relaxation portion at a position corresponding to the stress concentration portion applied to the joining member and the second electrode portion are joined by rotating the first component or the second component. A joining method characterized by.

1 LSI chip 2 Board 3,5,8 LSI chip electrode pad 4,6,9 Board electrode pad 7 Solder bump 10,11,12,13,14,20 Bonding structure 21 LSI chip center 22 Bump center 23 LSI pad target Side 24 Board pad target side 25 LSI chip center direction 26 Diagonal line 27 LSI chip outer circumference 28 LSI chip electrode pad center 29 Board electrode pad center 30 tangent line 32 LSI chip electrode pad 42 Board electrode pad 51 Vacuum suction jig 70, 80 Parts 71,81 Electrode 72,73 Bump 82 Relaxation 91 Joining member 100,200 Mounting structure

Claims (8)

The first component having the first electrode portion and
A second component having a second electrode portion and
A joining member for joining the first electrode portion and the second electrode portion is provided.
The joining member joins the first electrode portion and the second electrode portion in a state of being displaced from each other.
A part of the first electrode portion has a first relaxation portion at a position corresponding to the stress concentration portion applied to the joint member.
The first electrode portion and the second electrode portion are rotated with respect to the other component with the center of one component, which is one of the first component or the second component, as a rotation axis. The space between them is joined by the joining member.
The first electrode portion includes the first relaxation portion composed of a first curve or a first straight line in which a part of the first electrode portion has a smaller curvature than the other portions, and the first curve or the first electrode portion. Formed in combination with a second curve corresponding to the other portion having a greater curvature than the first straight line
The first electrode portion is a joining structure characterized in that the first component is rotated and joined to the second component in the same direction as the rotation. The first electrode portion has a second curve having a curvature larger than the shape of the first relaxation portion.
The joining structure according to claim 1 . The first relaxation portion is provided so as to face the center side of the first component, and the second curve faces the outside of the first component.
A second relaxation portion is provided in a part of the second electrode portion, and the second relaxation portion is a first curved portion having a radius of curvature different from that of the other portion of the second electrode portion. The second electrode portion has a second curved portion having a curvature larger than the shape of the second relaxation portion.
The second curved portion is provided so as to face the center side of the second component, and the first curved portion faces the outside of the second component.
The joining structure according to claim 2 . The first electrode portion is the tangent line of the first curve or the angle formed by the first straight line with respect to the second straight line from the apex to the center of the first component, and the first component is the first component. The joining according to any one of claims 1 to 3 , wherein the parts 2 are rotated and joined in the same direction as the rotation direction so as to change by an angle corresponding to the rotation. Construction. The joining structure according to claim 1, wherein the first relaxation portion is formed by a curve having a curvature opposite to that of the second curve . The first electrode portion of the first component and the second electrode portion of the second component are provided at opposite positions according to any one of claims 1 to 5 . The described joint structure. The mounting structure having the bonding structure according to any one of claims 1 to 6 . The first electrode portion of the first component and the second electrode portion of the second component, which are arranged at opposite positions, are joined by using a joining member.
At the time of the joining, the first electrode portion having the relaxation portion at the position corresponding to the stress concentration portion applied to the joining member and the second electrode portion are separated from each other by the first component or the second component. The first electrode portion and the second electrode portion are joined by the joining member in a state of being rotated with respect to the other component with the center of one component as the rotation axis.
The first electrode portion includes the relaxation portion in which a part of the first electrode portion is composed of a first curve or a first straight line having a smaller curvature than the other portions, and the first curve or the first. Formed in combination with a second curve corresponding to the other portion having a greater curvature than a straight line,
A joining method comprising joining the first electrode portion by rotating the first component in the same direction as the rotation of the first component with respect to the second component.

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