JP4822774B2 - Board bonding method and mounting board - Google Patents

Description

  The present invention relates to a substrate bonding method such as flip chip mounting.

FIG. 8 shows a flip-flop mounting process.
When the semiconductor chip 1 is mounted on the substrate 2 as shown in FIG. 8C, first, solder balls 4 are formed on the terminal portions 3 of the semiconductor chip 1 as shown in FIG. As shown in FIG. 8B, the semiconductor chip 1 is set upside down on the terminal portion 5 of the substrate 2, and the solder ball 4 is melted and solidified by heating in this state and returning to normal temperature. Complete.

  Further, a special method for forming bumps as shown in FIGS. 10A and 10B is known. First, as shown in FIG. 10A, a heat foamable eutectoid 8 is formed on the aluminum electrode 7 of the substrate 6 by electroplating. 9 is an insulating layer and 10 is a protective layer. In the subsequent heating step, the heat foamable eutectoid 8 is decomposed or gasified when the bump material is melted to form voids in the bump material. As shown, a spherical bump electrode 11 is formed.

As shown in FIG. 10C, the substrate 6 on which the void electrode is formed is pressed against the substrate 12 to be mounted and heated, and the bump electrode 11 is remelted and bonded.
JP-A-4-186663

  When the pitch of the terminal portions 3 of the semiconductor chip 1 is reduced as shown in FIGS. 9A and 9B, the interval between adjacent solder balls is reduced, and as shown in FIG. When the solder ball 4 is melted and solidified, a defective mounting portion (A) due to a solder bridge occurs.

  Therefore, when the pitch is reduced, it is possible to reduce the occurrence of defective mounting locations (A) by forming bumps of an appropriate size using the heat-foamable eutectoid 8 shown in FIG. Currently, there is a demand for a reduction in the number of processes.

  Further, when the conventional heat-foamable eutectoid 8 is foamed and solidified into a spherical shape as shown in FIG. 10B, the resistance value of the bump material dispersed therein is increased by foaming. There is.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate bonding method capable of improving the mounting reliability by eliminating the occurrence of solder bridges even when the pitch of terminal portions of a semiconductor chip is small, and reducing the number of steps.

  It is another object of the present invention to provide a substrate bonding method capable of realizing connection with a lower resistance.

In the substrate bonding method according to the first aspect of the present invention, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, the first and second electrodes are connected . The foamed bump material supplied on the first electrode is heat-treated by causing the substrates to face each other at intervals, and the foamed bump material is foamed until it comes into contact with the second electrode. The bump material in the material is melted to join the first electrode and the second electrode .

  In the substrate bonding method according to claim 4 of the present invention, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, the first electrode is foamed. Bump material is supplied, and one of the first and second substrates is placed on the other substrate so that the first electrode and the second electrode are in contact with each other via the foam bump material, and the foam bump The material is foamed, and the bump material in the foam bump material is melted and bonded.

  In the substrate bonding method according to claim 5 of the present invention, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, the first electrode is foamed. A bump material is supplied, and one of the first and second substrates is placed on the other substrate so that the first electrode and the second electrode are in contact with each other via the foam bump material, and the foam bump material The foam-type bump material is foamed in a state where the first electrode and the second electrode are in contact with each other and moved relative to each other in the direction in which the distance between the two substrates is increased to melt the pump material in the foam-type bump material. It is characterized by joining.

In the substrate bonding method according to claim 6 of the present invention, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, the lower layer of the first electrode is arranged a foam-type bump material, the foam-type bump material foamed through the hole of the first electrode is projected on the first electrode, wherein the foam which projects from the hole of the first electrode with contacting the first electrode and the second electrode through the die bump material, characterized by joining the foamable bump material in the first electrode and the second electrode by melting bump material.

In the substrate bonding method according to claim 8 of the present invention, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, A foaming agent is disposed on the lower layer of one electrode, a bump material is disposed on the foaming agent, and the foaming agent is foamed so that the bump material protrudes from the hole of the first electrode onto the first electrode. The first electrode and the second electrode are brought into contact with each other through the bump material protruding from the hole of the first electrode, and the bump material is melted to join the first electrode and the second electrode . It is characterized by that.

The mounting substrate according to claim 9 of the present invention is a mounting substrate in which the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps and mounted. The foamed bump material is provided in a lower layer of the first electrode of the first substrate, and the foamed bump material is foamed and protrudes from the hole of the first electrode above the first electrode. The first electrode and the second electrode are in contact with each other, and the bump material in the foamed bump material is melted to join the first electrode and the second electrode .

  According to this substrate bonding method, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by the bump, the foaming agent is supplied to the first electrode, and the foaming is performed. The outside of the agent is covered with a bump material, the first electrode and the second electrode are brought into contact with each other via the bump material expanded by expanding the foaming agent, and the bump material is melted and bonded to form a foaming agent. The bump material and the bump material are not mixed with each other, but the foaming agent and the bump material have a two-layer structure. Improvement can be realized, and the conductive layer made of the bump material is left along the outer surface of the foaming agent even by foaming of the foaming agent, so that bonding with low resistance is possible.

  Further, when the first electrode formed on the first substrate and the second electrode formed on the second substrate are connected by bumps, a foam bump material is supplied to the first electrode, and the first and second electrodes are supplied. The first electrode and the second electrode are brought into contact with each other through the foamed bump material by foaming the foam bump material, and the bump material in the foam bump material is melted. Thus, the number of processes can be reduced.

The substrate bonding method of the present invention will be described based on specific embodiments.
(Embodiment 1)
FIG. 1 shows a mounting process according to the substrate bonding method of the present invention.

Here, as shown in FIG. 1E, a mounting step of connecting the first electrode 22 formed on the first substrate 21 and the second electrode 24 formed on the second substrate 23 with bumps is performed. Show.
In FIG. 1A, a heat-foamable foaming agent 26 is supplied onto the first electrode 22 by a dispenser 25. In FIG. 1B, the skin layer 27 is formed by irradiating ultraviolet rays to solidify only the surface of the foaming agent 26. The foaming agent 26 cannot be used with ordinary urethane because of its poor heat resistance and chemical resistance. Therefore, foamed silicone is used in this embodiment and the embodiments described later. There are two types of foamed silicone. One is to add a foaming material by heating into silicone rubber and heat it to foam. The other is a two-component mixed type. And this foams by mixing. Specifically, sodium hydrogen carbonate mixed with silicone was used as a foaming agent. Since this decomposition temperature was 120 ° C to 150 ° C, the temperature of the foaming process was also set to 120 ° C to 150 ° C.

  In FIG. 1C, the bump material 29 is supplied onto the skin layer 27 by the dispenser 28 to cover the foaming agent 26. As the bump material 29, a conductive paste was used also in this embodiment and the embodiments described later. For example, the following can be used. Other conductive pastes can also be used. 100 parts by weight of bisphenol A epoxy resin, 6 parts by weight of tributyl borate as an additive, 15 parts of “Amicure PN-23” (Ajinomoto Co., Inc., trade name) as a solid dispersion type latent curing accelerator, Add 80 parts of “TMTP (Trimethylol Probantris (β-thioprovionate))” (trade name of Sakai Chemical Co., Ltd.) as a polythiol compound, and thoroughly mix with a universal mixer to prepare a resin assemblage. A conductive resin composition in which 400 parts of silver powder was mixed as conductive particles with respect to 100 parts by weight of the product was used. When conductive particles containing nanoparticles are used, even when the foaming agent is expanded by foaming, the particles are uniformly stretched and hardly break. Since the conductive paste includes a resin component, the conductive paste can be extended even if the foaming agent 26 is extended.

Since the skin layer 27 is formed on the surface of the foaming agent 26 when the bump material 29 is supplied, the foaming agent 26 and the bump material 29 are not mixed.
By performing the heat treatment in this state, the foaming agent 26 foams and its volume increases, and as a result, the bump material 29 covering the outside of the foaming agent 26 is expanded, as shown in FIG. A spherical bump 30 is formed.

  In FIG. 1E, the bump material 29 is remelted and solidified by pressing the second electrode 24 of the second substrate 23 against the bump 30 and heat-treating, and the first electrode 22 and the second electrode 24 are solidified. Are joined by the bump material 29.

  According to this substrate bonding method, even in a narrow pitch of about 20 μm, there was no bonding failure due to a bridge or the like, and a good bonding state could be obtained. Further, since the foaming agent 26 and the bump material 29 are not mixed with each other but have a two-layer structure of the foaming agent 26 and the bump material 29, the foaming agent 26 is foamed to the outer surface of the foaming agent 26. A conductive layer made of the bump material 29 is left along, and bonding with low resistance is possible.

  In FIG. 1A, the foaming agent 26 is disposed on the first electrode 21 by the dispenser 25. However, the foaming agent is formed on the first electrode 21 by using a printing or inkjet head without using the dispenser 25. 26 can also be arranged.

(Embodiment 2)
FIG. 2 shows a mounting process according to the substrate bonding method of the present invention, and a bump having a two-layer structure of a foaming agent 26 and a bump material 29 is used as in (Embodiment 1). The process of 2 (c) is the same as the process of FIGS. 1 (a) to 1 (c). In the first embodiment, after the foaming agent 26 is foamed in FIG. 1D, the bump material 29 is remelted in FIG. 1D to join the first electrode 22 and the second electrode 24 together. In this (Embodiment 2), before foaming the foaming agent 26 in FIG. 2 (d), the first and second substrates 21 and 23 are opposed to each other at an interval, and heating is performed in FIG. 2 (e). The difference is that the foaming agent 26 is foamed by the treatment and the bump material 29 is melted and joined by raising the temperature, and the heat treatment is performed only for foaming in FIG. Compared to the case where the material 29 is remelted, in FIG. 2E, the foaming agent 26 and the bump material 29 are remelted in the same process, so the number of processes can be reduced.

  In (Embodiment 2), the two-layered bump of the foaming agent 26 and the bump material 29 is used. However, even in the case of the bump in which the foaming agent 26 and the bump material 29 are mixed, the number of steps Reduction effect is obtained.

(Embodiment 3)
FIG. 3 shows a mounting process according to the substrate bonding method of the present invention, and a bump having a two-layer structure of a foaming agent 26 and a bump material 29 is used as in (Embodiment 2). The process of 3 (c) is the same as the process of FIGS. 1 (a) to 1 (c).

  In (Embodiment 2), the first and second substrates 21 and 23 are opposed to each other with a gap therebetween, and the foaming agent 26 is waiting for foaming to become large. In FIG. 3D, the second substrate 23 is placed on the bump 30 before foaming the foaming agent 26, and then the foaming agent 26 is foamed by heat treatment. As the foaming agent 26 foams, the second substrate 23 is lifted up to FIG. 3E, and the bump material 29 is melted and bonded by raising the temperature.

(Embodiment 4)
FIG. 4 shows a mounting process according to the substrate bonding method of the present invention, and a bump having a two-layer structure of a foaming agent 26 and a bump material 29 is used as in (Embodiment 2). The process of 4 (c) is the same as the process of FIG. 1 (a)-FIG.1 (c).

  In (Embodiment 2), the first and second substrates 21 and 23 are opposed to each other with a gap therebetween, and the foaming agent 26 waits for foaming to become large, but this (Embodiment 4) In FIG. 4D, the second electrode 24 of the second substrate 23 is placed in contact with or in the vicinity of the bump 30 before foaming the foaming agent 26, and then subjected to heat treatment to remove the foaming agent 26. In addition to foaming, the second substrate 23 is gradually separated from the first substrate 21 to the position shown in FIG. 4F through FIG. More specifically, the shape of the bump 30 is changed by separating the second substrate 23 from the first substrate 21 so that the foaming foaming agent 26 foams while contacting the second electrode 24 of the second substrate 23. In the range of the first electrode 21 and the second electrode 24, it can be controlled so as to be foamed and enlarged, and even in the case of a narrow pitch, a mounting failure portion (A This is effective in reducing the occurrence of).

  Here, the second substrate 23 is raised with respect to the first substrate 21, but the first substrate 21 is lowered with respect to the second substrate 23, or the first electrode 21 and the second electrode This can also be realized by moving the first substrate 21 and the second substrate 23 relative to each other so that the interval of 24 increases as the foaming agent 26 foams.

(Embodiment 5)
FIG. 5 shows a mounting process according to the substrate bonding method of the present invention.
In each of the above embodiments, the pump 30 disposed on the first electrode 22 is enlarged by the foaming of the foam material 26. In this (Embodiment 5), the inside of the first substrate 21 is described in detail. The bump 30 </ b> A in which the foaming agent 26 and the bump material 29 are mixed is disposed below the first electrode 22.

FIG. 5A to FIG. 5D show a process for forming the first substrate 21.
Here, the first substrate 21 includes a substrate lower portion 31 and a substrate upper portion 32 bonded to the substrate lower portion 31. A first electrode 22 is provided on the upper portion 32 of the substrate. A concave portion 33 is formed in the lower portion 31 of the substrate corresponding to the position of the first electrode 22.

In FIG. 5A, the bump 30A in which the foaming agent 26 and the bump material 29 are mixed is supplied to the concave portion 33 of the substrate lower portion 31 by a dispenser.
5 (b) and 5 (c), a through hole 34 reaching the substrate upper part 32 from the first electrode 22 is formed by laser processing, and then the lower part of the substrate to which the bump 30A has been supplied in FIG. A substrate upper part 32 is attached to 31 as shown in FIG.

  5E, the first substrate 21 attached as shown in FIG. 5D is placed on the heating plate 35 and heated. By this heating, the foaming agent 26 mixed in the bump 30A is foamed and the volume of the bump 30A is increased, and the bump 30A is formed on the first electrode 22 via the through hole 34 as shown in FIG. Protrudes.

  In FIG. 5G, the second substrate 23 is placed on the bumps 30 </ b> A protruding above the first electrode 22. The first electrode 22 and the second electrode 24 are joined by lowering the temperature of the heating plate 35 to a temperature at which the bump material 29 is remelted and then solidified.

  In this way, since the outlet of the foamed bump 30A is actively narrowed by the through hole 34, even if the bump 30A is small, the bump 30A can be protruded largely to the upper part of the first electrode 22, and bonding is performed due to the narrow pitch. Even when the number of bumps 30A per location cannot be increased, a reliable bonding state can be obtained.

(Embodiment 6)
FIG. 6 shows a mounting process according to the substrate bonding method of the present invention, and the processes of FIGS. 6A to 6F are the processes of FIGS. 5A to 5F of the fifth embodiment. Is the same.

  In (Embodiment 5), the second substrate 23 is placed on the bump 30A protruding above the first electrode 22. In FIG. 6 (g) of this (Embodiment 6), the second substrate 23 is placed. After the second electrode 24 of the substrate 23 is placed in contact with or near the bump 30 and brought into contact with the bump 30A in the middle of foaming, the second substrate 23 is gradually moved along with the foaming of the foaming agent 26 as shown in FIG. After the state of (h), it is separated from the first substrate 21 to the final state of FIG. 6 (i). More specifically, the second substrate 23 is made to foam so that the bumps 30 </ b> A that foam and protrude above the first electrode 22 foam while contacting the second electrode 24 of the second substrate 23. By separating from 21 to the position shown in FIG. 6 (i), the shape of the bump 30A can be controlled so as to protrude largely within the range of the first electrode 21 and the second electrode 24. Remelting and solidifying is effective in reducing the occurrence of defective mounting locations (A) due to solder bridges with adjacent electrodes, even in the case of narrowing the pitch.

  Here, the second substrate 23 is raised with respect to the first substrate 21, but the first substrate 21 is lowered with respect to the second substrate 23, or the first electrode 21 and the second electrode This can also be realized by moving the first substrate 21 and the second substrate 23 relative to each other so that the interval 24 increases with the protrusion of the bump 30A.

(Embodiment 7)
FIG. 7 shows a mounting process according to the substrate bonding method of the present invention.
In the above (Embodiment 5), a material in which the foaming agent 26 and the bump material 29 are mixed is used as the bump 30A. In this (Embodiment 7), a two-layer structure of the foaming agent 26 and the bump material 29 is used. The only difference is that the bump 30B is used.

In FIG. 7A, the foaming agent 26 is supplied by the dispenser 25 to the concave portion 33 of the substrate lower portion 31.
In FIG. 7B, the bump material 29 is further supplied onto the foaming agent 26 by the dispenser 28. When supplying the bump material 29, the surface of the foaming agent 26 is irradiated with ultraviolet rays as necessary to form a skin layer.

  In FIG. 7C and FIG. 7D, a through hole 34 reaching the substrate upper part 32 from the first electrode 22 is formed by laser processing, and then the lower part of the substrate to which the bump 30B has been supplied in FIG. 7A. A substrate upper part 32 is attached to 31 as shown in FIG.

  7E, the first substrate 21 attached as shown in FIG. 7D is placed on the heating plate 35 and heated. By this heating, the foaming agent 26 of the bumps 30B is foamed to increase the volume of the bumps 30B, and the bumps 30B protrude above the first electrodes 22 through the through holes 34 as shown in FIG.

  In FIG. 7G, the second substrate 23 is placed on the bumps 30 </ b> B that protrude above the first electrodes 22. The first electrode 22 and the second electrode 24 are joined by lowering the temperature of the heating plate 35 to a temperature at which the bump material 29 is remelted and then solidified.

  In this way, since the outlet of the foamed bump 30B is actively narrowed by the through-hole 34, even if the bump 30B is small, the bump 30B can be protruded largely to the upper part of the first electrode 22, and the bonding is performed due to the narrow pitch. Even when the number of bumps 30B per location cannot be increased, a reliable bonding state can be obtained.

  Further, since the foaming agent 26 and the bump material 29 are not mixed with each other but have a two-layer structure of the foaming agent 26 and the bump material 29, the foaming agent 26 is foamed to the outer surface of the foaming agent 26. A conductive layer made of the bump material 29 is left along, and bonding with low resistance is possible.

  Although the foaming agent 26 and the bump material 29 are supplied by the dispenser, the foaming agent 26 and the bump material 29 can be disposed on the first electrode 21 using printing or an inkjet head.

  Further, the processing of the distance between the first and second substrates 21 and 23 in FIG. 7G and FIG. 7H in this (Embodiment 7) is as shown in FIG. 6G and FIG. As in the case, the first substrate 21 and the second substrate 23 can be moved relative to each other so that the distance between the first electrode 21 and the second electrode 24 increases as the bump 30B protrudes. .

  In the above (Embodiment 5) to (Embodiment 7), the bump 30B is protruded above the first electrode 22 by heat treatment, and then the second substrate 23 is opposed to the first substrate 21. However, after the second substrate 23 is opposed to the first substrate 21, the bumps 30 </ b> B may be protruded and bonded to the upper portion of the first electrode 22 by heat treatment.

  The present invention can realize high-density mounting of various electronic devices and contribute to miniaturization of electric devices.

Process drawing of semiconductor mounting method of (Embodiment 1) of this invention Process drawing of semiconductor mounting method of (Embodiment 2) of this invention Process drawing of semiconductor mounting method of (Embodiment 3) of this invention Process drawing of semiconductor mounting method of (Embodiment 4) of this invention Process drawing of the semiconductor mounting method of (Embodiment 5) of this invention Process drawing of semiconductor mounting method of (Embodiment 6) of this invention Process drawing of semiconductor mounting method of (Embodiment 7) of this invention Process diagram of conventional mounting method using solder balls Process diagram in the case of narrow adjacent by the mounting method of the conventional example Process diagram of another conventional semiconductor mounting method

Explanation of symbols

21 First substrate 22 First electrode 23 Second substrate 24 Second electrode 26 Heat-foamable foaming agent 27 Skin layer 29 Bump material 30 Spherical bump 30A Bump 30B in which foaming agent 26 and bump material 29 are mixed Bump 31 having a two-layer structure of foaming agent 26 and bump material 29 Substrate lower part 32 Substrate upper part 33 Recessed part 34

Claims (9)

When connecting the first electrode formed on the first substrate and the second electrode formed on the second substrate with bumps,
The first and second substrates are opposed to each other with a gap therebetween,
The foam bump material supplied on the first electrode is heat-treated to foam the foam bump material until it contacts the second electrode, and the bump material in the foam bump material is melted. Joining the first electrode and the second electrode
Substrate bonding method. Foam type bump material is a two-layer structure of foaming agent and bump material,
After supplying the foaming agent to the first electrode, the surface of the foaming agent is cured and then coated with the bump material.
The substrate bonding method according to claim 1. Foam type bump material has a structure in which foaming agent and bump material are mixed.
The substrate bonding method according to claim 1. When connecting the first electrode formed on the first substrate and the second electrode formed on the second substrate with bumps,
Supplying foam bump material to the first electrode;
Placing one of the first and second substrates on the other substrate so that the first electrode and the second electrode are in contact with each other via the foam bump material;
A substrate bonding method in which the foam bump material is foamed and the bump material in the foam bump material is melted and bonded. When connecting the first electrode formed on the first substrate and the second electrode formed on the second substrate with bumps,
Supplying foam bump material to the first electrode;
Placing one of the first and second substrates on the other substrate so that the first electrode and the second electrode are in contact with each other via the foam bump material;
The foam bump material is foamed in a state where the first electrode and the second electrode are in contact with each other through the foam bump material, and is relatively moved in the direction in which the distance between the two substrates is increased. A substrate bonding method in which materials are melted and bonded. When connecting the first electrode formed on the first substrate and the second electrode formed on the second substrate with bumps,
Arranging foam bump material under the first electrode of the first substrate,
The foam type bump material foamed through the hole of the first electrode is projected on the first electrode,
With contacting the first electrode and the second electrode via the foam-type bump material which projects from the hole of the first electrode, the said first electrode by melting bump material of the foam type bump material A substrate bonding method for bonding the second electrode . The foam type bump material has a structure in which a foaming agent and a bump material covering the outside of the foaming agent or a mixture of the foaming agent and the bump material are mixed.
The board | substrate joining method in any one of Claims 4-6 . When connecting the first electrode formed on the first substrate and the second electrode formed on the second substrate with bumps,
A foaming agent is disposed under the first electrode of the first substrate, a bump material is disposed on the foaming agent,
Foaming the foaming agent and projecting the bump material from the hole of the first electrode onto the first electrode;
The first electrode and the second electrode are brought into contact with each other through the bump material protruding from the hole of the first electrode, and the bump material is melted to bond the first electrode and the second electrode. Joining method. A mounting substrate in which a first electrode formed on a first substrate and a second electrode formed on a second substrate are connected by bumps and mounted,
A foam-type bump material accommodating portion provided in a lower layer of the first electrode of the first substrate;
The first electrode and the second electrode come into contact with each other through the foamed bump material that has foamed and protruded from the hole of the first electrode onto the first electrode, and the bump material in the foamed bump material is melted. A mounting substrate in which the first electrode and the second electrode are joined.

Images