JPH01318289A - Manufacture of copper clad laminated board for multilayer printed board - Google Patents

Abstract

PURPOSE:To prevent linear dents produced at the time of heating, pressurizing and forming by providing a metal sheet having coefficient of thermal expansion equal to or more than a copper foil between the copper foil and a metal plate to heat, pressurize and form. CONSTITUTION:A metal sheet 2 is laid between a metal plate 3 and a constituent material 1 on both the faces of the constituent material, a few groups of this combination are superposed and a cushion material 4 is arranged between the metal plate 3 and a heat plate 5 of both the outmost sides to heat, pressurize and form. In the constituent material 1, prepreg 7 is arranged on both the faces of a copper clad laminated layer board 6 on which an inner layer circuit is formed on both the faces thereof and further the copper foil 8 is arranged on the outside thereof. A good result can be obtained when copper and aluminum having coefficient of thermal expansion equal to or more than the copper foil used for outer layer copper foil formation in the metal sheet are used. Thereby the occurrence of linear dents can be prevented and good laminated layer board can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a copper-clad laminate for a multilayer printed board.

[Conventional technology]

The manufacturing method of copper-clad laminates for multilayer printed boards uses one or more copper-clad laminates on which inner layer circuits are formed, prepreg is placed between the outer layer steel foil and the inner layer circuit board, and then the outermost A metal plate such as a stainless steel plate is placed on the surface and formed under heat and pressure to form a copper-clad laminate for multilayer printed boards. ◎ There are two ways to arrange the steel foil for the outer layer: using steel foil itself, and single-sided copper-clad laminate. There are examples of using laminates.

[Problem to be solved by the invention]

In the method of using the copper foil itself as a means of forming the steel foil for the outer layer, the copper foil of the copper-clad laminate for the inner layer is removed by etching in the area where there is no inner layer circuit during hot-pressure forming. Depth 5 to 1 on the outer layer steel foil
There is a drawback that linear depressions of about 8 μm are likely to occur. Although it is economically advantageous to use the copper foil itself to form the A foil for the outer skin, the formation of linear depressions as described above makes it impossible to form an outer layer pattern, making it difficult to use as a multilayer printed board. It becomes unusable.

Figure 3 shows the occurrence of linear bends. A prepreg 7 is stacked on both outer sides of a copper-clad laminate 6 on which inner layer circuits are formed on both sides, and an outer layer copper foil 8 is stacked on the outer side of the prepreg 7. When this material is heated and press-molded, linear depressions 9 are generated in areas where there is no inner layer circuit 10.

The present invention is for outer layer @++I? ? Third, it is an object of the present invention to solve the problem by preventing the above-mentioned linear depressions that occur when the copper foil itself is heated and press-molded.

[Means to solve the problem]

The present invention involves placing prepregs on the top and bottom of a copper-clad laminate on which at least one inner layer circuit is formed, and layering copper foil on both outer sides of the copper-clad laminate. In this method, a metal note having a coefficient of thermal expansion equal to or higher than that of the foil is interposed between the foil and the metal plate, and the blade is hot-pressed.

The method of the invention will be explained with the help of figures. FIG. 1 shows an example of the configuration between press W8 plates when molding is performed by the method of the present invention. A metal sheet 2 is interposed between the metal plate 3 on both sides of the constituent material 1, and several sets of this combination are stacked to form a gold J on both sides.
A cushion material 4 is placed between the A plate 3 and the hot plate 5. Second
The figure shows ten examples of constituent materials in the above implementation. A prepreg 7 is arranged on both sides of a copper-clad laminate 6 on which inner layer circuits are formed on both sides, and a steel foil 8 is further arranged on the outside thereof.

The metal notebook used in the present invention needs to be made of pine having a coefficient of thermal expansion equal to or higher than that of the copper foil used to form the outer copper foil. Good results are obtained when using metal glazes such as copper and aluminum. Thermal expansion coefficient is rolled @1.5X10-', stainless steel 1.2X10-', aluminum 2.4X
10-”.

The appropriate thickness of the metal sheet is 0.05 to 0.20 nm, and there is no effect outside this range.

Also, using an organic film instead of a metal sheet has no effect.

[Effect]

The linear depressions that are a problem in the present invention occur in the outer layer @ the depression portion, which corresponds to a portion where there is no inner layer circuit. This is because during hot-pressure molding, the friction between the copper foil corresponding to the area where the circuit is located and the gold plate for forming is large, and the friction between the steel foil and the metal plate is less likely to occur in areas where there is no circuit. . Therefore, if you place an object that eliminates friction between the copper foil and the gold plate, or an object that elongates more than the copper foil when heated and pressurized, it is thought that the linear dents will disappear.

Based on the above idea, a method was developed in which a gold leaf sheet is interposed between the outer layer copper foil and the metal plate for forming.

Since the Kinya sheet of the present invention has a large coefficient of thermal expansion and is soft, if the thickness of the notebook is too large, it will absorb the shape of the inner layer circuit and create a step in the shape of the inner layer circuit on the outer layer steel foil, making it unsuitable for casing. .

If it is too thin, it will not be effective in preventing linear depressions.

〔Example〕

Examples of the present invention will now be described. As shown in FIG. 2, the constituent material 1 shown in FIG.
The prepreg 7 with a thickness of 1 mm cL was arranged on both sides of a copper clad laminate 60 with a thickness of 18 μm, and copper W3B with a thickness of 18 μm was stacked on both outer sides of the prepreg 7.

As shown in FIG. 1, eight pieces of the constituent material 1 were dried and laminated alternately with stainless steel plates 3 with metal sheets 2 interposed between hot plates 5 of a press. The number of linear depressions in the outer copper foil layer of the copper-clad laminate for a multilayer printed board obtained by heat-pressing molding in this manner was investigated. The result is the first
Shown in the table.

In this example, the metals of the metal sheets were copper and aluminum, and the thicknesses thereof were varied.

[Comparative example]

In comparative examples, stainless steel was used as the metal sheet, no metal sheet was used, and a triacetate film was used in place of the metal sheet. Other than that, a copper-clad laminate for multilayer printing was molded under the same conditions as in the example, and the number of linear depressions generated in the outer layer steel foil was examined. The results are shown in Table 1.

Table 1 [Effects of the Invention] As is clear from the results in Table 1, the present invention has made it possible to prevent the occurrence of linear dents.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the implementation of the present invention, FIG. 2 is an explanatory diagram of the constituent materials in FIG. 1, and FIG. 3 is a diagram of the state in which linear depressions occur. 1... Constituent material, 2... Metal sheet, 3... Metal plate, 4...
Cook 1 Hayashi, 5...Hot plate, 6...
...Copper-clad laminated board, 7...Prepreg,
8... Copper foil, 9... Linear depression -10.
...Inner layer circuit. −−−−−−−−−−−−1-2 Metal sheet Figure 1

Claims (2)

[Claims] 1. In the production of copper-clad laminates for multilayer printed boards, prepregs are arranged on both sides of a copper-clad laminate on which at least one inner layer circuit is formed, and copper foil is layered on the outside. A method for manufacturing a copper-clad laminate for a multilayer printed board, which comprises laminating and forming a metal sheet having a coefficient of thermal expansion equal to or higher than that of copper foil between the layers. 2. The method for producing a copper-clad laminate for a multilayer printed board according to claim 1, wherein aluminum having a thickness of 2.0.05 to 0.20 mm is used as the metal sheet.