JPS63241993A - Multilayer printed board and manufacture of the same - 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] [Industrial Application Field] The present invention relates to a multilayer printed board and a method for manufacturing the same, and particularly relates to a multilayer printed board with high wiring density and a large number of laminated layers, and a manufacturing method suitable therefor. .

[Conventional technology]

The conventional method for manufacturing multilayer printed boards is disclosed in Japanese Patent Application Laid-open No. 56-30.
As described in Publication No. 797, a wiring pattern of copper foil is formed on the surface of a base material for a multilayer printed board, and at the same time, a frame-shaped copper foil is left on the outer periphery, and one or more strips are formed on the frame-shaped copper foil. The method for producing a multilayer printed board is characterized in that blank portions are provided and the relative positions of the blank portions on the front and back surfaces of the base material are alternately arranged so as not to overlap with each other.

Further, Japanese Patent Application Laid-Open No. 58-157192 describes a method for manufacturing a printed wiring board in which a copper foil having a linear or partially cut pattern remains on the periphery.

Further, JP-A-61-189688 describes a printed circuit board in which a frame-shaped copper foil portion is provided in a portion other than the circuit wiring portion.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, the entire base material including the copper foil pattern of the part of the multilayer printed board base material where the steel foil wiring pattern is provided on the surface and the part where multiple surrounding frame-shaped copper foil lines are provided on the surface. No consideration was given to keeping the elastic modulus and linear expansion coefficient close to each other, and when multiple base materials were stacked with prepreg sandwiched between them and bonded together by heating and pressurizing, the base materials were deformed due to heat shrinkage and curing shrinkage of the prepreg resin. There were different problems depending on the location.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer printed board and a method for manufacturing the same that can be used in a wide range of wiring densities by equalizing the above deformation in each location.

[Means for solving problems]

To summarize the present invention, the first invention of the present invention relates to a multilayer printed board, and the first invention relates to a multilayer printed board in which a plurality of printed board base materials made of an insulating board to which copper foil on which a wiring pattern is formed are laminated. The printed board is characterized in that a bent pattern made of one or more thin copper wires is provided around the wiring pattern portion of the printed board base material.

Further, a second invention of the present invention relates to a method for manufacturing the multilayer printed board according to the first invention, in which a printed board substrate is provided with a pattern B formed on a copper foil adhered to at least one surface of an insulating board. In a method of manufacturing a multilayer printed board by stacking a plurality of sheets with prepreg sheets in between and then applying heat and pressure, in any process of manufacturing the printed board base material, the wiring pattern of the printed board base material is It is characterized by a process in which a bent pattern made of one or more thin copper wires is provided around the area.

The purpose of bringing the elastic coefficients and linear expansion coefficients of the internal steel foil wiring pattern forming part of the multilayer printed board base material closer to that of the copper foil remaining part in the peripheral part is to bend the thin wires of the copper wire pattern provided in the peripheral part. This is achieved by

Insulating boards for multilayer printed boards are made of glass cloth impregnated with epoxy resin, polyimide resin, etc. and cured.
The linear expansion coefficient is 1000 to 2000 Kyf/v, respectively.
on the other hand, the longitudinal elastic modulus and linear expansion coefficient of copper foil are tL9000.
~110001if/m", 1.7 X 10-'C-
1, and the longitudinal elastic modulus of the copper foil is more than five times higher than that of the insulating plate. First, the thickness of the copper foil bonded to the insulating board is 55-7.
0μm, and the thickness of the insulating plate is 100βm@shun. For this reason, the presence or absence of steel foil greatly changes the elastic modulus of the printed board substrate, in particular. The longitudinal elastic modulus Fa when the copper foil and the insulating plate are integrated can be expressed by the following equation +11.

Here, Ef: Modulus of longitudinal elasticity of the insulating plate Eo: Modulus of longitudinal elasticity of the copper foil tf: Thickness of the insulating plate to: Thickness of the copper foil For example, the front and back sides of an insulating plate with a thickness of 100 μm have a thickness of 35
After bonding copper foil of μm to the entire printed board base material, the average longitudinal elastic modulus E of the entire printed board base material is Ef=10001c17f/w",
Kc = 100 Q Okf/fz-tort 11)
The equation color Ea=4706 KfA-, which is more than four times the value of an insulating board without copper foil. For this reason, when multiple layers of Gripreg are sandwiched between base materials and bonded under pressure, the flow of the resin during pressure and the amount of deformation of the base material due to curing and shrinkage of the resin are affected by the difference in elastic modulus depending on the presence or absence of copper foil. varies greatly. In particular, if a portion with a high elastic modulus exists at the periphery of the printed board substrate, the center of each side of the outer periphery of the P substrate will deform inward due to curing shrinkage of the resin, causing strain at each location on the substrate. The distribution will look very different.

Therefore, in order to solve this problem, the present invention bends the copper foil wire formed around the base material into a shape such as a sine wave, a triangular wave, a trapezoidal wave, a rectangular wave, or a combination thereof. This is to reduce the rigidity of the outer periphery of the board in the side direction. This stiffness reduction occurs due to the following mechanism. When the linear pattern of copper foil is formed linearly in the side direction, the tensile stiffness of the copper foil in the side direction is the product of the elastic modulus, thickness, and width, but if the copper foil wire is bent In this case, the stiffness of the curved beam and the width of the curved copper wire are 1 mm,
When the bending period is about 10 degrees, the stiffness of the copper wire in the side direction is 1.
It can be reduced to 40 or less. Therefore, it is possible to match the rigidity of the outer circumferential portion of the substrate and the internal wiring pattern forming portion, and it is possible to equalize the strain generated at each location during lamination bonding.

The method of providing a peripheral pattern of copper wire on the outer periphery according to the present invention can be performed simultaneously with the formation of an internal wiring pattern, as in the conventional method. However, a peripheral pattern may be formed before or after forming the wiring pattern, or a separately created pattern may be fixed.

Next, the peripheral pattern may be formed of a plurality of parallel copper wires.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 One embodiment of the present invention will be described with reference to FIGS. 1 to 3.

That is, FIG. 1 is a top view of a printed board substrate according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line A-A' in FIG. FIG. 3 is a configuration diagram showing the arrangement of each village when laminating multiple layers using sheets.

In each figure, 1 is the peripheral copper wire, 2 is the copper foil wiring, 5 is the insulating plate, 4 is the guide hole, 5 is the printed board base material, 6 is the prepreg sheet, 7 is the jig plate, and 8 is the guide bin. means.

Two prepreg sheets impregnated with epoxy resin are stacked on glass cloth, and copper foil with a thickness of 35 μm is layered on the front and back sides of the sheets and bonded by heating and pressure.
After making the CL, a resist film is applied to the surface of the valley copper foil,
By exposing the peripheral pattern and wiring pattern shown in FIG. 1 and FIG. Base material 5 was obtained. A guide hole 4 is made in this printed board base material 5, and when a plurality of printed board base materials are stacked and bonded, a guide hole 4 is passed through to prevent misalignment between each layer. The printed board base material 5 obtained in this manner and prepreg sheets 6 made of glass cloth impregnated with epoxy resin are alternately laminated as shown in FIG. Finally, after applying the upper jig plate, the prepreg sheet 6 was placed between the hot plates of a press, heated and pressed to cure the prepreg sheet 6, and each printed board base material was adhered to obtain a multilayer printed board. The bending angle of the peripheral steel wire 1 employed here with respect to the outer edge of the multilayer printed board was ±45°. Further, the width of the peripheral copper wire 1 is 10 mm, and the number of repeated pinches is 80 mm. The deformation state of the multilayer printed board obtained in this way is shown in B of Fig. 1.
When evaluated by the amount of deviation from the straight line at points C and D,
Peripheral copper wire without bending (width 10 ww, ) t
- It was confirmed that the reduction was 40% compared to the case where it was used.

Example 2 Another embodiment of the invention is illustrated in FIG.

That is, FIG. 4 is a top view of 174 parts of a printed board base material according to one embodiment of the present invention, and the symbols 1 to 4 have the same meanings as in FIG. 1.

In the embodiment shown in FIG. 4, the peripheral steel wire 1 has a sinusoidal bend. Width of peripheral steel wire 1 101+
111. The repetition pitch was 80 m, and it was confirmed that the amount of deviation from the long side from the @ line was further reduced by 5% compared to the example shown in FIG.

Example 3 Another embodiment of the present invention will be described with reference to FIGS. 5 and 6.

That is, FIG. 5 is a top view of 174 parts of a printed board base material according to an embodiment of the present invention, and FIG. 6 is a sectional view taken along line E-E' in FIG. It is synonymous with figure.

The embodiment shown in FIG. 5 has a bending angle of ±45° with respect to the outer edge of the multilayer printed board of the peripheral steel wire 1, similar to the embodiment shown in FIG.
However, two 5W wide copper wires were used.

By reducing the width of the copper wire to 1/2, the rigidity in the side direction of the copper wire portion can be reduced to 1/4. In this example, the amount of deformation on each side (deviation from the straight line ik) is as shown in Figure 1. An additional 10% decrease was confirmed compared to the case of .

〔Effect of the invention〕

As explained above, according to the present invention, when a printed circuit board base material on which a printed circuit is formed is laminated and bonded using a prepreg sheet, the amount of strain generated due to curing shrinkage of the prepreg sheet and temperature change is determined by location. The difference is 4 according to the present invention.
Since it can be made more uniform, it is possible to reduce the relative deviation between the eyebrows by laminating them. As a result, it is no longer necessary to increase the size of the pad in which the through hole connecting each layer is provided by the amount of relative deviation, and accordingly, there is an effect that the wiring density of the printed circuit can be increased.

[Brief explanation of drawings]

FIG. 1 is a top view of a printed board base according to an embodiment of the present invention;
Figure 2 is A-A'lfi of Figure 1! A sectional view, FIG. 3 is a configuration diagram showing the layout of each village when the printed board base material shown in FIG. 1 is laminated in multiple layers using prepreg sheets, and FIGS. 4 and 5 are one embodiment of the present invention. FIG. 6 is a top view of a quarter part of the printed board base material of the example, and is a sectional view taken along the line g-E' in FIG. 5.

Claims (1)

[Claims] 1. In a multilayer printed board in which a plurality of printed board base materials each made of an insulating board to which a copper foil on which a wiring pattern is bonded is laminated, the area around the wiring pattern portion of the printed board base material is , a multilayer printed board characterized by being provided with a bent pattern consisting of one or more thin copper wires. 2. The multilayer printed board according to claim 1, wherein the pattern of the copper wire is a bent pattern consisting of a sine wave, a triangular wave, a trapezoidal wave, a rectangular wave, or a combination thereof. 3. The multilayer printed board according to claim 1 or 2, wherein the copper wire pattern is formed of a plurality of parallel copper wires. 4. In a method of manufacturing a multilayer printed board by stacking a plurality of printed board base materials with a wiring pattern formed on copper foil bonded to at least one side of an insulating board with a prepreg sheet sandwiched between them, and then applying heat and pressure. , characterized in that, in any process of manufacturing the printed board base material, a process is performed to provide a bent pattern made of one or more thin copper wires around the wiring pattern portion of the printed board base material. Method for manufacturing multilayer printed boards.