JPH0588560B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a multilayer printed wiring board used for mounting various so-called semiconductor chips or other chip parts, and a method for manufacturing the same, and particularly relates to this multilayer printed wiring board and its manufacturing method. The manufacturing method is applied to packages such as chip carriers and pin grid arrays. (Prior art) In recent years, electronic components called semiconductor chips, etc.
The degree of integration has become extremely dense, and as a result, the printed wiring boards on which they are mounted must also become denser. Multilayer printed wiring boards were developed to deal with this situation. This multilayer printed wiring board is designed to accommodate the mounting of highly integrated electronic components by forming conductor circuits in advance on the multiple boards that make up the board, and then bonding these boards together. be. Conventionally, Purpreg with glass cloth or adhesive sheet without glass cloth has been used to bond the multilayer printed wiring boards developed in this way, but even if these are joined by pressing, the multilayer printed wiring boards cannot be bonded. It has the disadvantage of poor adhesion due to poor followability between inner layer patterns. In addition, with prepregs and adhesive sheets, it is difficult to control the flow of the resin that makes up the sheets to areas other than those to be bonded. The disadvantage is that the length of the dot cannot be ensured. In other words, if the resin protrudes onto the bonding pad, the bonding pad will become electrically insulated and will no longer function as a bonding pad. In other words, the multilayer printed wiring board bonded with the conventional adhesive sheet is not bonded with resin to the bonding pads 25a of the pin grid array, which is the multilayer printed wiring board 200, as shown in FIGS. 4 and 5. It is easy for resin to protrude 28 and it is difficult to control the amount thereof, and if the amount of resin extrude 28 is large, it becomes difficult to ensure electrical continuity. Furthermore, when the amount of resin protruding 28 is small, voids 29 are likely to occur between the substrate 20 and the adhesive sheet 24a, resulting in poor adhesion between the substrates 20. In the conventional technology, there was no example of using an adhesive made of resin or the like to bond the upper and lower substrates of a multilayer printed wiring board, and there was no void-free adhesive with a small amount of resin protruding. be. (Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances. The reliability of the printed wiring board itself is poor due to the difficulty in ensuring electrical continuity between the board parts and the insufficient adhesiveness of the bonding parts between the boards. It is an object of the present invention to provide a multilayer printed wiring board that ensures electrical continuity in bonding pad portions and strengthens the adhesiveness between substrates, and a method for manufacturing the same. (Means for Solving the Problems) In order to solve the above problems, the first means taken by the present invention is that the lower substrate 10a on which the electronic component mounting portion 11 and the conductor circuit 15 are formed, and the electronic Opening 12 and conductor circuit 15 corresponding to component mounting section 11
This is a multilayer printed wiring board 100 constructed by laminating at least one upper substrate 10b on which a The adhesive 14a used has the following composition. (a) 70 parts by weight of a heat-resistant epoxy resin composition composed of a heat-resistant epoxy resin consisting of a bis-phenol type epoxy resin and a novolak type epoxy resin, and a curing agent consisting of dicyandiamide. (b) 30 to 50 parts by weight of silane coupling-treated fused silica or crystalline silica and 5 to 10 parts by weight of amorphous silica. (c) 30 parts by weight of a solvent consisting of methyl cellosolve, butyl cellosolve and dimethylformamide. That is, in the multilayer printed wiring board 100 according to the first means, the adhesive 14a having the composition of (a) to (d) above is applied to the lower substrate 10a to be bonded to each other.
The adhesive layer 14 is formed by interposing the adhesive layer between the substrate and the upper substrate 10b and curing the adhesive layer. The multilayer printed wiring board 100 according to the present invention having the above configuration will be explained in more detail according to the specific example shown in the drawings. FIG. 1 shows a multilayer printed wiring board 1 according to the present invention.
A multilayer printed wiring board 100 in this embodiment is a pin grid array, and consists of a total of four boards 10 as shown in FIG. Each of these substrates 10 is mainly made of a resin material, and the bonding portions thereof are bonded with an adhesive having the above-described composition of the present invention. In addition, among these substrates 10, when specifically explaining the upper and lower parts, "upper substrate 10b" and "lower substrate 10b" are used.
a", and when referring to them collectively, they will be simply expressed as "substrate 10". FIG. 3 is an enlarged vertical cross-sectional view of a part of the bonding part, showing the adhesive 14a to the bonding pad 15a.
There is almost no protrusion of the substrate 10 and adhesive 1.
No voids are generated between 4a. These are achieved by applying adhesive 14a to a portion of each substrate 10 by a method such as printing, and after drying this adhesive 14a to the touch, laminating each substrate 10 by pressing. be. Next, the second means taken by the present invention will be explained. This second means is a method for manufacturing the multilayer printed wiring board 100 described above, and includes the following steps. (1) Applying an adhesive 14a having the composition below to a part of the lower substrate 10a on which the electronic component mounting portion 11 and the conductor circuit 15 are formed; (2) Applying the adhesive 14a on the lower substrate 10a with a finger. (3) At least one upper substrate 10b in which the opening 12 corresponding to the electronic component mounting portion 11 and the conductive circuit 15 are formed, and the lower substrate 10a are bonded with adhesive 14.
A step of laminating via a. The composition of the adhesive 14a used here is as follows. (a) 70 parts by weight of a heat-resistant epoxy resin composition comprising a heat-resistant epoxy resin consisting of a bis-phenol type epoxy resin and a novolak type epoxy resin, and a curing agent consisting of dicyandiamide. (b) 30 to 50 parts by weight of fused silica or crystalline silica treated with silane coupling and 5 to 10 parts by weight of amorphous silica. (c) 30 parts by weight of a solvent consisting of methyl cellosolve, butyl cellosolve and dimethylformamide. That is, in this second means, the adhesive 14a having the above composition is applied to a part of the lower substrate 10a on which the electronic component mounting portion 11 and the conductor circuit 15 are formed, and then the adhesive 14a is applied. Dry to the touch,
Thereafter, the upper substrate 10b and the lower substrate 10a are bonded together by pressing or the like. (Function of the invention) First, the multilayer printed wiring board 100 according to the present invention
In this case, since the adhesive 14a having the above composition is used, even if the adhesive 14a is interposed between the upper substrate 10b and the lower substrate 10a and is pressed and cured, the adhesive 14a is Upper substrate 10b and lower substrate 1
It does not protrude beyond the area where it is bonded to 0a. Therefore, each bonding pad 15
This means that there is no adhesive 14a on point a that would impede electrical continuity. In addition, on the contrary, since the adhesive 14a has good followability between the conductor circuits, the adhesive 14a can be used between the upper substrate 10b and the lower substrate 1.
It does not enter between 0a and create voids as in the conventional case, and the bonding between the two is ensured. Furthermore, the multilayer printed wiring board 10 according to the present invention
In the case of manufacturing method 0, adhesive 14 having the above composition
a, and dry it to the touch after applying it, so the upper substrate 10b and the lower substrate 10
The adhesive 14a does not adhere to any other material when bonding the upper substrate 10b and the lower substrate 1.
This makes the work of joining 0a easier. (Example) Next, multilayer printed wiring board 100 according to the present invention
Examples of the adhesive 14a required for the manufacturing method will be described in detail. This adhesive 14a has the above-mentioned composition, and in this composition, fused silica or It is important to blend 30 to 50 parts by weight of crystalline silica and 5 to 10 parts by weight of amorphous silica. The reason for this is to prevent bleeding when the adhesive 14a is applied to a portion of each substrate 10 by a method such as printing, and to prevent the resin from extruding during subsequent pressing. This is because the blending ratio is essential. Note that this heat-resistant epoxy resin is composed of a bis-phenol type epoxy resin and a novolak type epoxy resin, and its curing agent is composed of dicyandiamide, so a mixed solvent of methyl cellosolve, butyl cellosolve, and dimethyl formamide is used as the solvent for these. There is. This adhesive 14a is made of fused silica (DRS-SI-20 manufactured by Tatsumori Co., Ltd., maximum particle size 5 μm) that is coated with a heat-resistant epoxy resin to improve its water resistance.
And Aerosil Lot300 (manufactured by Nippon Aerosil Co., Ltd.) for improving printability was mixed at a blending ratio of 39.8 parts by weight and 9.6 parts by weight, respectively, to 70 parts by weight of a heat-resistant epoxy resin composition composed of a heat-resistant epoxy resin and a curing agent. It is made into a varnish by passing it through three rolls, and the heat-resistant epoxy resin composition and solvent are mixed at a ratio of 7:3. In addition, when a resin made into a varnish with a blending ratio other than the above is tested with two other blending ratios as shown in the table below, in the case of A in the table, bleeding after printing occurs. After heat treatment at 80℃ for 30 minutes, bleeding occurred and depressions appeared on the pattern, while in the case of B in the table, bleeding did not occur after printing, but 80℃ After heat treatment at ℃ for 30 minutes, depressions appeared on the pattern. However, in the case of C in the table, there was no bleeding after printing and the condition was good after heat treatment at 80° C. for 30 minutes.

[Table] In addition, when using the adhesive 14a as described above as a solder resist by printing, it is preferable to color it to make it easier for the printer to judge splattering and bleeding after printing. As a specific coloring method, carbon black may be added to the adhesive 14a having the above composition at a ratio of 0.5 to 1.0%. The reason for this is that if the film thickness after printing is 50 μm, which is the commonly used thickness, if it is less than 0.5%, the solder resist will look blank and the merit of coloring will be reduced.
Conversely, if the amount of carbon black added to the adhesive 14a exceeds 1%, the insulation with the conductor circuit 15 will deteriorate. When an adhesive consisting of this composition is subjected to an evaluation test,
Durability for 3 minutes when immersed in a soldering bath at 260℃, thermal shock test at room temperature 25℃ for 15 seconds at 260℃ for 10
200 cycles of repeated immersion in a second oil bath,
Pressure pump test for 150 hours or more and pressure test for 10 hours, then 260 hours
It has been confirmed that no change occurs when immersed in a solder bath at ℃ for 10 seconds. In addition, when printing continuously, the solvent in the adhesive, mainly the low boiling point solvent methyl cellosolve (BP 124°C), tends to volatilize and lead to an increase in viscosity, so the high boiling point solvent butyl cellosolve (BP 172°C) is By injecting with a Spencer, the viscosity is returned to printable viscosity of 250 to 300 voids and continuous printing is possible. The adhesive 14a used in the present invention is of a melting type, and in order to crush voids, it is necessary to
After printing on 0a, dry to the touch at 50℃ to 80℃, and bonding is done using a vacuum press to control voids and the amount of resin protrusion.Additionally, the corners of the multilayer printed wiring board are designed with a tapered shape. ,
Bonding can be performed by appropriately controlling the resin film thickness and amount of resin protrusion. (Effects of the Invention) As detailed above, in the multilayer printed wiring board 100 according to the present invention, as exemplified in the above embodiment, the adhesive 14a having the following composition, that is, (a) bis- 70 parts by weight of a heat-resistant epoxy resin composition comprising a heat-resistant epoxy resin consisting of a phenol type epoxy resin and a novolak type epoxy resin, and a curing agent consisting of dicyandiamide. (b) 30 to 50 parts by weight of silane coupling-treated fused silica or crystalline silica and 5 to 10 parts by weight of amorphous silica. (c) 30 parts by weight of a solvent consisting of methyl cellosolve, butyl cellosolve and dimethylformamide. and a lower substrate 10a on which an electronic component mounting section 11 and a conductor circuit 15 are formed, and at least one upper substrate 10b on which an opening 12 corresponding to the electronic component mounting section 11 and a conductor circuit 15 are formed.
and are laminated via the adhesive 14a formed on a portion of the lower substrate 10a, ensuring electrical continuity at the bonding pad portion and strengthening the adhesion between the substrates 10. Therefore, a multilayer printed wiring board 100 can be provided. That is, the bonding between the lower substrate 10a and the upper substrate 10b of the multilayer printed wiring board 100 according to the present invention as shown in FIG.
It is strengthened by the insertion of resin between the layers and the adhesion of the resin on the outermost printed wiring board and the middle board.
The water resistance at those interfaces is also good, and the substrate 10
This made it possible to strengthen the adhesion between the two. Further, as a result, the multilayer printed wiring board 100 according to the present invention does not require an adhesive sheet such as prepreg, so that the multilayer printed wiring board can be made at low cost. Note that in this case, bonding using only adhesive resin has the effect of being simple. Furthermore, the adhesive 14a used in the present invention can be printed on general printed wiring boards, and is used to permanently protect circuits and prevent solder bridging between circuits when soldering components. It can also be used as a permanent mask as a solder resist. On the other hand, in the manufacturing method according to the present invention, the adhesive 14a having the above composition is employed, and (1) the following is applied to a part of the lower substrate 10a on which the electronic component mounting portion 11 and the conductor circuit 15 are formed. (2) A step of drying the adhesive 14a on the lower substrate 10a to the touch; (3) An opening 12 corresponding to the electronic component mounting portion 11 and a conductor circuit 15 are formed. At least one upper substrate 10b and a lower substrate 10a are bonded together using an adhesive 14.
A step of laminating via a. By doing so, it is possible to easily manufacture the multilayer printed wiring board 100 having the above-mentioned effects.

[Brief explanation of the drawing]

FIG. 1 is a front perspective view of a multilayer printed wiring board according to the present invention, and FIG. FIG. 3 is a partially enlarged longitudinal cross-sectional view of the joint portion along the line in FIG. 2. FIG. 4 is a vertical cross-sectional view of a multilayer printed wiring board bonded using a conventional adhesive sheet, and FIG. 5 is a partially enlarged vertical cross-sectional view of the bonded portion indicated by the line in FIG. Explanation of symbols, 100...Multilayer printed wiring board,
DESCRIPTION OF SYMBOLS 10...Substrate, 10a...Lower substrate, 10b...Upper substrate, 11...Electronic component mounting part, 12...Opening, 14...Adhesive layer, 14a...Adhesive, 15...
...Conductor circuit, 15a...Bonding pad, 1
6... Through hole, 16a... Conductor layer, 17...
...Conductor pin.

Claims (1)

[Scope of Claims] 1. A lower substrate on which an electronic component mounting portion and a conductor circuit are formed, and at least one upper substrate on which an opening corresponding to the electronic component mounting portion and a conductor circuit are formed, 1. A multilayer printed wiring board, characterized in that the multilayer printed wiring board is constructed by laminating a portion of the board through an adhesive having the composition shown below. (a) 70 parts by weight of a heat-resistant epoxy resin composition composed of a heat-resistant epoxy resin consisting of a bis-phenol type epoxy resin and a novolak type epoxy resin, and a curing agent consisting of dicyandiamide. (b) 30 to 50 parts by weight of silane coupling-treated fused silica or crystalline silica and 5 to 10 parts by weight of amorphous silica. (c) 30 parts by weight of a solvent consisting of methyl cellosolve, butyl cellosolve and dimethylformamide. 2. The multilayer printed wiring board according to claim 1, wherein each of the substrates is made of a resin material. 3. The multilayer printed wiring board according to claim 1 or 2, wherein the multilayer printed wiring board is a chip carrier or a pin grid array. 4. A method for manufacturing a multilayer printed wiring board comprising the following steps. (1) A step of applying an adhesive having the composition below to a part of the lower board on which the electronic component mounting area and conductor circuit are formed; (2) A step of drying the adhesive on the lower board to the touch; ( 3) A step of laminating at least one upper substrate in which an opening corresponding to the electronic component mounting portion and a conductor circuit are formed, and the lower substrate via the adhesive. Composition of adhesive; (a) 70 parts by weight of a heat-resistant epoxy resin composition composed of a heat-resistant epoxy resin consisting of a bis-phenol type epoxy resin and a novolak type epoxy resin, and a curing agent consisting of dicyandiamide. (b) 30 to 50 parts by weight of silane coupling-treated fused silica or crystalline silica and 5 to 10 parts by weight of amorphous silica. (c) 30 parts by weight of a solvent consisting of methyl cellosolve, butyl cellosolve and dimethylformamide.