JPS60178694A - Method of producing multilayer printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF APPLICATION OF THE INVENTION The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a multilayer molding method suitable for laminating and adhering printed wiring boards.

[Background of the invention]

FIG. 1 is a cross-sectional view showing a conventional general multilayer molding method for a multilayer printed wiring board. Between two surface layers 10 each having a conductor circuit formed on one side of the double-sided steel clad laminate, an intermediate layer 2 having a conductor circuit formed on both sides of the double-sided copper clad laminate and a prepreg 3 are placed in position according to a positioning bin 4. They can be layered alternately while being aligned. Although only one intermediate layer 2 is shown in the figure, generally a plurality of intermediate layers 2 are laminated alternately with the prepreg 3. In addition to adhering each layer, prepreg 3 also has the role of insulating each layer and filling the holes on each surface where conductor circuits are formed with resin, so it is generally used for each intermediate layer with two layers and The lower surface layer 1° prepreg 3. Middle class 2. Prepreg 3. After fitting the upper surface layer 1 into the positioning pins 4 one after another, the positioning pins 4 are fitted into the positioning holes in the two adhesive jig plates 5 to integrate the scissors. . In addition,
6 is a release film that prevents the adhesive jig plate 5 from being contaminated with resin. The upper and lower surface layers 1 and the intermediate layer 2 are formed by heating and pressurizing the upper and lower adhesion jig plates 5 between the heaters 7 and 7 of a hot press (not shown), thereby forming prepreg layers interposed between each layer. are fixed together, thus forming a multilayer printed wiring board. Note that 8 is a spacer that serves to reduce thermal conductivity in order to correct variations in temperature distribution of the heating device 7.

The prepreg 3 for adhering the surface layer 1 and the intermediate layer 2 or between the intermediate layers 2 is generally constructed by impregnating and coating a glass cloth with a semi-cured resin such as an epoxy resin. When the prepreg is heated, the impregnated semi-cured resin temporarily decreases in viscosity and flows out, and then shrinks and hardens to bond the printed wiring boards on both sides. This impairs the dimensional stability of prepregs and printed wiring boards. That is, when the glue preg that flows out shrinks and hardens, it acts to pull the printed wiring board that is adhered to it, and as a result, the printed wiring board also undergoes dimensional changes. FIG. 2 is a sectional view of a multilayer printed wiring board showing this state. Since the surface layer 1 and the intermediate layer 2 have different thicknesses and conductor circuit patterns, the amount of dimensional change caused by the melted and hardened prepreg 6 also differs. Therefore, for example, land portions 9 and 9' of the conductive circuit pattern of the printed wiring board are misaligned between the two layers as shown in FIG. In addition, the positioning bin 4 prevents the prepreg 3 from flowing out or shrinking and hardening, and prevents the tensile force from the adhesive jig plate 5 due to the difference in thermal expansion coefficient and thermal expansion rate between the adhesive jig plate 5 and the printed wiring board. It acts on the wiring board, and the printed wiring board near the positioning bin 4 is locally deformed. For these reasons, the land portion 9 should be removed in the post-process.
, 9' is shifted from the center of the land portion 9' in the intermediate layer 2, and a portion of the hole is located in a place where the land portion 9' is not formed. Sometimes I put it away. This means that electrical continuity is cut off to the through hole in the part that is off the land part 9.9', so if a conductor circuit pattern happens to be wired at that position, The result is the same as a disconnection, which is a drawback that cannot be overlooked.

[Purpose of the invention]

An object of the present invention is to provide a multilayer molding method that reduces positional deviation between layers during lamination and bonding of printed wiring boards, which is a drawback in the conventional method.

[Summary of the invention]

In the present invention, when laminating and bonding printed wiring boards, first, only the peripheral part of the printed wiring board is laminated and bonded by heating and pressurizing, and the central part is only pressurized to relatively position each layer, Thereafter, the entire flint wiring board is laminated and bonded by heating and pressure, so that each layer of the printed wiring board integrally undergoes the same amount of dimensional change without positional shift, thereby achieving the object of the present invention. This is what we are trying to achieve.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 3, 1.2.5, 4.5, and 6 are the same as in FIG. 2, a prepreg 5 made of glass epoxy, and a release film 6 are shown. 8 is the same as that shown in FIG. 1, and is a spacer inserted between the bonding jig plate 5 and the hot press heater. In Fig. 5, 10 and 11 are hot press (
(not shown). The heating devices 10 and 11 have a thickness of 5
QIII steel plate with several hollowed out tubes of diameter 251111 through which steam and water commonly flow. In other words, when raising the temperature, steam is passed through the pipe, and when cooling, water is run.

A perspective view of the lower heaters 10 and 11 is shown in FIG. The heating device used in this example is divided into two independent parts in order to achieve the object of the present invention. In other words, it is divided into a central heating device 10 and a peripheral heating device 11.

The distance between the two heating vessels 10 and 11 is 3 mm, and the mutual flatness variation is 0.021111 or less. Broken line 12
indicates where the outline of the printed wiring board is located, and a broken line 13 indicates where the conductor circuit pattern area of the printed wiring board is located.

Therefore, the printed wiring board stacked between the two adhesive jig plates 5 in FIG. 3 is placed between the upper and lower heating plates via the spacer 8 so that its position is as shown in FIG. It will be destroyed. The positioning bin 4 is located outside the conductor circuit pattern area of the printed wiring board. In other words, 4 positioning bins,
It is located within the area of the heating device 11.

In FIG. 3, 15 is during lamination bonding of printed wiring boards;
That is, when the hot press is under pressure, the rubber backing is used to seal the space between the upper and lower heating plates, and it is fixed to the upper heating plate. Further, numeral 14 indicates a vacuum degassing device having a vacuum pump, which maintains a vacuum state of less than bOTorr between the upper and lower heating plates during lamination and bonding of printed wiring boards. this is,
In order to prevent void defects, that is, air bubbles from remaining after the prepreg 3 between each layer of the printed wiring board melts and hardens during lamination bonding of the printed wiring board, the air between each layer of the printed wiring board that causes this is removed. This is for forced removal.

The operation of this embodiment will be explained using FIG. The printed wiring board, that is, the surface layer 1, is first superimposed between two adhesive jig plates 5 under a surface pressure of 14 kg/cr/l in a heater at room temperature. The intermediate layer 2 and the prepreg 3 are pressurized. In addition, after sealing the space between the upper and lower heating plates with the rubber backing 15, the vacuum air device 14 is operated to seal the space between the upper and lower heating plates at 60 Torr.
Create a vacuum below r. Thereafter, while maintaining the pressure, water is flowed through the tubes of the central heater 10, and steam is flowed through the peripheral heater 11 to raise the temperature to 130°C. The state is 2
By holding for 0 minutes, only the printed wiring board in the area of the peripheral heating device 11, that is, the portion of the printed wiring board including the positioning bin 4 outside the area of the conductor circuit pattern is laminated and bonded. Next, while maintaining the surface pressure at 141 cg/crA, steam was poured into the heater 10 instead of the water.
The heating device 10 is also heated to 130° C. in the same manner as the heating device 11, and this state is maintained for 20 minutes to bond the entire printed wiring board. In addition, in order to accelerate the polymerization reaction of the epoxy resin of the prepreg 6, the heating plates 10 and 1 were then heated.
The temperature of Step 1 was raised to 170° C., and this state was maintained for 60 minutes. Thereafter, water is flown in place of the steam flowing through the heaters 10 and 11 to cool them to room temperature, and then the pressure is released to complete the lamination bonding process.

According to this embodiment, by first laminating and bonding the outside of the conductor circuit pattern area including the positioning bin 4 of the printed wiring board, the entire printed wiring board including the inside of the conductor circuit pattern area of the next printed wiring board is laminated and bonded. ) - Prepreg 6 during adhesion
Since the outflow of the prepreg is restrained, the prepreg does not receive the tensile force caused by the flowing out of the prepreg as in the conventional method, but receives only the tensile force caused by shrinkage and hardening of the prepreg. However, since each layer is positioned relative to each other around the entire periphery of the printed wiring board, dimensional changes within the conductive circuit pattern area of each layer are restrained, and misalignment between each layer can be significantly improved compared to conventional methods. In general, when measuring the amount of positional deviation at the outermost part of the conductor circuit pattern where the amount of positional deviation is maximum, it was found to be 100 μm in the conventional method, but in this embodiment, it was significantly reduced to about 50 μm. Further, local deformation of the printed wiring board near the positioning bin 4 could be completely eliminated.

In addition, in the conventional method, the Gripreg does not flow out, so the thickness of the multilayer printed wiring board after lamination bonding tends to be thicker in the center than in the peripheral part, and the variation in board thickness is 0. Although there was a difference of li or more, this tendency disappeared in this example, and the &:r fluctuation of the plate thickness was able to be reduced to 0.1 to 0.1 or more.

[Effects of the Invention] As described above, according to the present invention, when laminating and bonding printed wiring boards, I-1 first, only the peripheral portion of the printed wiring board is laminated and bonded, and each layer is positioned relative to each other. By applying this method, it is possible to relatively restrain the dimensional changes of each layer when the entire printed wiring board is laminated and bonded, so that the positional shift between each layer can be significantly reduced compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional general method for forming multiple layers of a multilayer printed wiring board, FIG. 2 is a sectional view showing misalignment between the eyebrows of a multilayer printed wiring board, and FIG. FIG. 4 is a sectional view similar to FIG. 1 showing the chemical forming method, and FIG. 4 is a perspective view of the −F side heating device of the hot press according to the embodiment of the present invention. 1. Surface layer, 2. Intermediate layer, 3. Prepreg, 4. Positioning pin, 5. Adhesive jig plate, 6. Release film, 7, 10, 11.. Heater, 8. Spacer, 9. 9' Land Department, 14 Vacuum Deaerator, Patent Attorney Akio Takahashi First Country 4 10 4

Claims (1)

[Claims] A process of alternately overlapping a plurality of printed wiring boards and prepregs, a process of sandwiching and integrating the loose parts from above and below with adhesive jig plates after overlapping, and then the above-mentioned integration by heating and pressurizing. In the manufacturing process of a multilayer printed wiring board, which comprises a step of laminating and bonding printed wiring boards, only the peripheral portion of the integrated printed wiring board is laminated and bonded by heating and pressure during the lamination and bonding, 1. A method for manufacturing a multilayer printed wiring board, comprising the steps of applying only pressure to the central portion, and then laminating and bonding the entire printed wiring board by heating and applying pressure.