JPS5873192A - 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] This relates to printed wiring boards that can be manufactured.

Conventionally, laminates made by impregnating a paper base material or a glass cloth base material with resin and laminating and molding the same are well known, but it is difficult to increase the density when mounting chips on these laminate boards.

For example, one high-density mounting method is to mount a leadless chip carrier on a board, but this has the problem of deterioration of the connection between the chip and the board because the coefficients of thermal expansion between the chip and the board are different. .

Therefore, there is a report that it is advantageous to mount a chip on a laminate made of aromatic polyamide cloth (IEEE Transactions on Co., Ltd.).
mponenta, )(ybrids and Ma
Nufacturing Technology vol.
, CHMT-2, Nol, P140March,
1979).

This method has the advantage that it is possible to make the coefficient of thermal expansion of the substrate and the chip the same value, and that the reliability of the connection part is high.

However, when a printed wiring board is made using aromatic polyamide fibers, the tongue-like extensions due to the ablation properties of aromatic polyamide fibers are elongated during processing. Since the plated layer of the through hole is covered with the metal foil layer, there is a drawback that incomplete connection occurs between the plated layer of the through hole and the metal foil.

The present invention has been made based on the above-mentioned matters, and is a method for preparing and cleaning the inner surface of a through-hole in a printed wiring board using a prepreg obtained by impregnating a cloth containing at least aromatic polyamide fibers with a resin. It is an object of the present invention to provide a printed wiring board that can reliably connect parts and metal layers.

The present invention is characterized by impregnating a cloth made of glass fibers with a resin between the first prepreg obtained by impregnating a cloth containing at least aromatic polyamide fibers with a resin and the metal foil. The obtained second prepreg is interposed therebetween.

Hereinafter, a multilayer printed wiring board as an embodiment of the printed wiring board of the present invention will be explained in detail using FIG. 1.

In FIG. 1, l is the first prepreg obtained by impregnating a cloth having at least aromatic polyamide fibers with a resin, and a typical example of the aromatic polyamide fibers is polyP-phenylene terephthalamide. There are poly-P-benzamide type fibers, poly-P-benzamide type fibers, etc. 2 is a second cloth obtained by impregnating a cloth made of glass fiber with resin.
This second prepreg 2 is laminated on both the upper and lower surfaces of the first prepreg 1. Representative examples of glass fibers include E-glass fibers, C-glass fibers, A-glass fibers, and the like. 3 is a metal foil such as copper. By drilling a hole in the substrate constructed in this manner and plating the inner surface of the hole, a through hole 4 is formed and is joined to the metal foil 3.

In the above embodiment, the first prepreg 1 is made of aromatic polyamide fibers, but it goes without saying that aromatic polyamide fibers and glass fibers may be mixed and twisted.

Second! ! ! , I are detailed illustrations of the present invention,
This is an enlarged view of a part of the cross section of a through-hole portion that was formed after lamination. After processing, a tongue-like extension 5 as shown in the figure is formed on the inner surface of the bleep rig 1, which is made of glass-reinforced aromatic polyamide fibers. If the substrate #jI structure according to the present invention is not used, this tongue-shaped extension portion 5 will cover the metal foil layer 3, and will smoothly connect to the four electric bodies 1- on the inner surface of the through hole that will be formed later by plating. do not. According to the present invention, by arranging the prepreg 2 made of glass fiber reinforced with plastic on both sides of the metal foil 13, the metal foil and the through-hole plated portion can be smoothly connected.

Examples Brominated bisphenol Am epoxy resin (1 epoxy resin
480g/eQ) 90 weight jtff15, cresol novolac type epoxy resin (per epoxy* 220g/eq
) 9 parts of methyl ethyl ketone and methyl cellosolve as common media were added to 10 parts of heavy electric current, 4 parts of dicyandiamide, 0.2 parts of benzyldimethylamine, and a 37% production face was prepared. On the other hand, polyP-
Feuenile/Telegetalamide fiber (manufactured by DuPont, KE
'R weave using VLAI (,49, type 965.195 denier), weaving density: 34 vertically, 34 horizontally/25-
I made a cross of width. In addition, glass fiber (manufactured by Nitto U, G
-50058ZG) was woven and the weaving density was 56 vertically and 4 horizontally.
0 / 25 I made a sag spirit cross.

Dip these cloths into the above fest and heat at 160C.
By drying for 5 minutes, first and second prepregs were obtained.

Next, a multi-no printed wiring board consisting of #I as shown in FIG. 1 was prepared using these preble, g and @m (70μ).

That is, between the tanizuna fan shields (conductor layers), a prepreg made of aromatic polyamide fiber cloth is sandwiched between prepregs made of glass fiber on both sides.

With this structure, 8 layers were formed and heated to 60°C at 170C.
A multilayer printed wiring board having a thickness of 2.03 mm was obtained by pressing for 1 minute.

The pressed thickness of each I-component was 370 μm of copper, 50 μm of the layer made of glass fiber, and 110 μm of the layer made of aromatic polyamide fiber.

For the multilayer printed wiring board as described above, a printed wiring board Komei drill (Igetalloy, SPD30M0.50T) is used.

0.5φ), and set the rotation speed to i x io' rpm
~6X10' rpm, drill feed speed 2005m
/M ~2000 txs/I processed the through hole with Ryu.

Next, when we observed the cross-section of the through-hole after processing using a scanning electron microscope, we found that the tongue-like extension of the layer made of aromatic polyamide fibers covered the layer made of glass fibers in two or three circumferential places. The maximum thickness was 40μ in the thickness direction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the printed wiring board of the present invention,
FIG. 2 is an enlarged view showing a part of the cross section of the through hole portion in the printed wiring board of the present invention. DESCRIPTION OF SYMBOLS 1... First prepreg, 2... Second prepreg, 3... Metal foil, 4... Metsukino-15... Tongue-shaped extension part. ￥J 1 Ward% 2 3

Claims (1)

[Claims] 1. A cloth made of glass fibers is impregnated with a resin between the first prepreg obtained by impregnating a cloth containing at least aromatic polyamide fibers with a resin and the metal foil. A printed wiring board with the obtained second prepreg interposed therebetween. 2. The printed wiring board according to claim 1, wherein the cloth forming the first prepreg is made of a composite yarn made by twisting a mixture of aromatic polyamide fibers and glass fibers.