JP2003031949A - Multilayer board, manufacturing method and bonding structure thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliability and high-density multilayered board, its manufacturing method and an bonding structure. SOLUTION: The multilayer board, formed by mutually adhering wiring boards, is composed of a first wiring board 7, a second wiring board 3, a conductive material 5 for electrically connecting the first board 7 with the second board 3, and bonding structures 1, 2 for bonding the wiring boards each other. The adhering structure 1, 2 is composed of a porous layer 1 and adhesive layers 2 provided on both surfaces of the porous layer for adhering to the wiring boards.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer substrate for a high-density wiring board, a method for manufacturing the multi-layer substrate, and a bonding structure.

[0002]

2. Description of the Related Art Recently, as electronic devices such as personal computers have become higher in density and smaller in size, IC packages have also been required to have higher density and smaller in size. Conventional QFP (Quad Flat P) for high density and miniaturization of IC packages
BGA (Ball Grid Ar) that can support more terminals than IC package of package type)
ray) type has been introduced. Also, with respect to the board on which the package is mounted, the number of layers and miniaturization are progressing, and development of a multilayer board by build-up is also active. on the other hand,
As a method of providing a low-cost, high-performance multi-layer substrate, a composite multi-layer substrate in which a multi-layer flexible substrate is pasted on a conventional printed circuit board or ceramic multi-layer substrate has been introduced.

Usually, a laser is used to form a via in a bonded substrate, but the resin film layer and the adhesive layer to be bonded are simultaneously opened. After the laser opening, the smear in the via is removed by a wet process or a dry process such as plasma. Filling with conductive resin, solder balls, melting of solder paste, electroless or Ni, C by electroplating
Electrical connection is established between the layers by the method of forming the metal layers of u and Au.

[0004]

The substrate thus manufactured is surface-mounted in a reflow process after screen printing of solder paste and mounting of various packages. The reliability test of the board is defined by the Japanese Industrial Standards JIS, the Japan Printed Circuit Board Association JPCA, etc., but the soldering heat resistance test is a particularly important test when the package is surface-mounted on the board. . According to the above-mentioned standard, the board is usually absorbed in a hot and humid mist atmosphere for a predetermined time, and then put into a reflow furnace or immersed in a molten solder bath. At this time, the moisture absorbed in the composite multi-layer substrate may be vaporized to cause a problem such as occurrence of peeling voids in the adhesive layer used for bonding.

Therefore, the present invention has been made to solve the above problems, and when a resin film is attached to a rigid substrate to manufacture a multi-layer substrate, the adhesive layer causes peeling of an adhesive portion or the like. An object of the present invention is to provide a high-density multi-layer substrate which can be prevented and is highly reliable in the process of assembling various electronic components, a manufacturing method thereof, and a bonding structure.

[0006]

In order to solve the above problems, the method of manufacturing a multilayer substrate according to the present invention is as follows. First, an adhesive film is laminated on both sides of the porous film to produce a three-layer structure for adhesion in which the porous film is sandwiched by the adhesive.

Next, a via hole (through hole or blind via) is formed in the resin film substrate by using a photo-etching process which is a wet method, and then a conductor wiring is formed. A resin film having conductor wiring and via holes is laminated with an adhesive film sandwiching a porous film. In addition, the formation of the adhesive layer on the porous film may be performed by applying a film-like adhesive to the porous film with a roll coater and then drying.
The resin film and adhesive film are attached to a rigid printed circuit board.

After the bonding, the adhesive layer containing the porous film under the via hole is removed with a laser,
It is a method for manufacturing a multilayer printed circuit board, which is obtained by filling a conductive resin paste into a via hole.

The function of the porous layer included in the adhesive layer is that the moisture contained in the resin film, the rigid substrate, and the adhesive, which are the constituent elements of the composite multi-layered substrate, evaporates rapidly, and The gas generated during the curing process of a certain conductive resin or the gas generated during the curing of the adhesive is efficiently discharged from the adhesive layer through the gap between the porous layers included in the adhesive layer. It Therefore, it does not accumulate at each adhesive interface, does not cause peeling and void generation in each adhesive layer, and the adhesive penetrates into the porous layer to improve the adhesive force between the adhesive layer and the porous film due to the anchor effect. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A resin film substrate bonded with an adhesive film sandwiching a porous film of the present invention is
A general flexible tape having a wiring pattern formed on one side or both sides of a resin film is used. TA
A conventional manufacturing method can be applied to the manufacturing method of the B tape or the PPC tape. The size and shape of the film and the substrate may be appropriately designed according to the size and shape of the semiconductor device to be applied.

A general printed board is used as the rigid board. The adhesive for sandwiching the porous film may be any one of a room temperature bonding type, a thermosetting type and a thermoplastic type. Regarding the thickness of the adhesive, it is possible to select any thickness, but it is desirable to keep the total thickness of the adhesive and the porous film thin, and therefore, a thickness of 20 μm to 100 μm is usually used.
The porous film sandwiched between the adhesives is required to have an appropriate pore size and gas permeability in order to efficiently discharge the gas generated from the inside of the system and to maintain the adhesive force with the adhesives. However, it can be selected appropriately. In this way, the high-density wiring board of the present invention is formed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a cross-sectional structure when thermosetting adhesive layers are formed on both sides of a porous film, and FIG. 2 is a flexible printed circuit board using a film obtained by laminating an adhesive on both sides of a porous film. FIG. 6 is a schematic diagram of a cross-sectional structure of a laminated substrate in which a rigid printed circuit board and a rigid printed circuit board are bonded together.

The manufacturing method will be mainly described with reference to FIGS. 1 and 2, and a thermosetting adhesive 2 (manufactured by Sumitomo 3M Co., Ltd.)
Adhesive 1592, film thickness 20 μm) was put into the atmosphere at a roll pressure of 0.3 MPa, a roll temperature of 70 ° C. and a laminating speed of 0.2 m / min using a laminator (FV-700 type) manufactured by Taisei Laminator Co., Ltd. Porous film 1 (manufactured by Nitto Denko Corporation, Microtex NTF113
1 and thickness of 25 μm).

Since it is a porous film, even if it is laminated in the air, it can sufficiently follow the irregularities of the porous film and no void is caught between the adhesive layer and the porous film. Using this porous film, flexible printed circuit film 3 (F
PC) and the rigid board 7 (printed circuit board of four layers) were bonded together. The bonding is performed by aligning through holes (diameter 1.5 mm) on the printed circuit board and aligning through holes (diameter 1.5 mm) formed on the FPC.
(mmφ) was aligned with a jig of pin alignment method, and both were temporarily attached in the air at room temperature at a pressure of 0.1 MPa.

After that, by a uniaxial press machine, 150 °
C, 10 MPa pressure was applied for 10 minutes to perform final pressure bonding. Furthermore, in order to fully cure the adhesive, 150 ° C, 1
It was left open at 20 ° C. After curing, no peeling or void formation was observed at the interface between the printed circuit board and the adhesive, the flexible printed circuit board and the adhesive, or the porous film and the adhesive.

Furthermore, in order to establish electrical continuity between the wiring layers of the bonded FPC and the rigid printed circuit board,
Via formation was performed at a predetermined position using a carbon dioxide gas laser (LAVIA 1000TW) manufactured by Sumitomo Heavy Industries, Ltd. Here, the laser processing conditions are: output 1.8 W, frequency 500 Hz, shot number 8, beam diameter 280 μmφ
And After opening the via, a conductive paste (conductive silver paste manufactured by Sumitomo Metal Mining Co., Ltd.) was filled in the via by a printing method. After filling, it was cured in an oven at 150 ° C for 90 minutes. A solder heat resistance test was performed on the bonded substrates.

The test method is based on the Japan Printing Industrial Standards (IP
C / JPCA-6202, 6801 standard). In the solder heat resistance test, a temperature cycle of −40 ° C. to + 60 ° C. was performed 10 times at a cycle of 2 times per hour, and then the sample was dried at 105 ° C. for 24 hours, temperature 30 ° C., humidity 60. After performing a humidification treatment in a constant temperature and humidity chamber of% RH for 192 hours, an IR reflow furnace (temperature of 125 ° C for 120 seconds, 1 second
It was immersed in the molten solder twice at 260 ° C. for 10 seconds at a maximum temperature of 220 ° C. at a temperature of 83 ° C. or higher for 2-3 minutes.

After the solder heat resistance test, peel strength, observation of voids, and rate of change in conduction resistance ΔR of vias were examined. The conduction resistance change rate is calculated by the formula ΔR = | (Rf−Ri) / Ri | × 100
Calculated in%. Here, Rf is a resistance value after the solder heat resistance test, and Ri is an initial conduction resistance value. Evaluation,
A conduction resistance change rate of 20% or less was regarded as acceptable. As for the peel strength, it is 18 mm against the substrate with 10 mm width tape.
The strength when the tape was peeled off in the 0 ° direction was measured. A pass rate of 0.5 N / m or more was determined.

Comparative Example A laminated substrate was prepared in the same manner as in Example except that the adhesive did not include a porous film and the thickness of the adhesive was 65 μm.

Table 1 shows the results of void observation after bonding and after the solder heat resistance test, the peel strength measurement results after bonding and after the solder heat resistance test, and the results of conduction resistance for the examples and comparative examples. Show.

[0021]

[Table 1]

As is clear from Table 1, in Examples, voids after bonding, peel strength after bonding, voids after solder heat resistance test, peel strength after solder heat resistance test, and solder heat resistance test Good results were obtained with all of the rates of change in conduction resistance before and after, but in the comparative example, the voids after the solder heat resistance test and the rate of change in conduction resistance before and after the solder heat resistance test failed. was there.

[0023]

By using the adhesive having the porous film sandwiched between the present invention, when the adhesive is heated after the resin film and the rigid substrate are bonded together, or when the solder heat resistance test after moisture absorption is performed, Voids or peeling may occur at the interface between the adhesive layer and the adhesive layer or the adhesive layer and the material (polyimide, glass epoxy resin, etc.) in contact with it due to moisture or reaction gas generated from the glass epoxy resin or the like. Moreover, there is an effect that it is possible to suppress an increase in the conduction resistance value of the interlayer connection and improve the reliability of the laminated substrate.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cross-sectional structure of a film obtained by laminating an adhesive on both sides of a porous film in an example of the present invention.

FIG. 2 is a schematic diagram of a cross-sectional structure of a laminated substrate in which a flexible printed circuit board and a rigid printed circuit board are bonded together by using a film obtained by laminating an adhesive on both sides of a porous film in an example of the present invention. Is.

[Explanation of symbols]

1 Porous film 2 Adhesive layer 3 Flexible printed circuit board 4 Solder resist 5 Interlayer connection (via filled with conductive base) 6 wiring patterns 7 rigid printed circuit board 8 Inner layer wiring section

Claims (6)

[Claims] 1. A multi-layer substrate configured by adhering wiring boards to each other, wherein a first wiring board, a second wiring board, a first wiring board and a second wiring board are electrically connected. A conductive material to be connected to, and a bonding structure for bonding the wiring boards together,
The multilayer substrate, wherein the adhesive structure comprises a porous layer and adhesive layers provided on both sides of the porous layer for adhering to each wiring board. 2. A via is formed by bonding a resin film base material on which wiring is formed to both sides or one side of a rigid wiring board such as a ceramic wiring board or a printed wiring board using a thermosetting adhesive or a thermoplastic adhesive. After filling, a conductive material is filled in the vias, and when the metal wiring layers are electrically connected to each other to form a high density multilayer, the porous layer is sandwiched between the adhesive layers. High-density wiring board manufacturing method. 3. The method for manufacturing a high-density wiring board according to claim 2, wherein the film thickness of the porous layers sandwiched by the adhesive is 0.020 to 0.1 mm, preferably 0.03 to
0.06 mm with a porous pore size of 1-3 μm
A manufacturing method characterized by being. 4. The production method according to claim 2, wherein the resin film substrate is TAB (Tape Automat).
ed Bonding) tape or FPC (Fle)
A method for manufacturing a high-density wiring board, which comprises using a xisable printed circuit. 5. An adhesive structure for adhering wiring boards together, comprising a porous layer and adhesive layers provided on both sides of the porous layer for adhering to each wiring board. Adhesive structure to be. 6. The adhesive structure according to claim 5, wherein the film thickness of the porous layer is 0.020 to 0.1 m.
m, preferably 0.03 to 0.06 mm, and a porous pore size of 1 to 3 μm.