JPH03187293A - Manufacture of copper-clad laminate - Google Patents

Abstract

PURPOSE:To eliminate voids in a prepreg layer without linear recesses on an outer layer copper foil by using resins having specific viscosities as a prepreg in contact with an outer layer copper foil of a prepreg layer and a prepreg in contact with a laminate forming an inner layer circuit. CONSTITUTION:As a prepreg A in contact with an outer layer copper foil 2 of a prepreg layer 3, resin having 2000-3000 poises of lowest melting viscosity at 3 deg.C/min of temperature rising speed, and as a prepreg C in contact with a laminate 5 formed with an inner layer circuit 4, resin having less than 1500 poises of lowest melting viscosity at 3 deg.C/min of temperature rising speed is used. That is, as the prepreg A, the resin having high melting lowest viscosity, i.e., small fluidity is used. As the prepreg C, the resin having high fluidity is used. Thus, no linear recess is formed on the outer layer copper foil, and no void is generated in the prepreg layer.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The invention relates to steel-clad laminates for multilayer printed boards - manufacturing methods. Use one or more JLL-covered laminates on which inner layer circuits are formed.
A method of layering copper foil on the outer layer, which consists of a single-sided steel-clad 1MN plate for the outer layer via a prepreg impregnated with a resin of melting viscosity on a copper-clad 51-layer plate with circuits formed for the inner layer. There is. Both of these are heat-pressed and formed into steel-clad laminates for multiple unprinted boards. The compaction product/i1 molding pressure is usually kept constant at 10 to 60 kg/an', or σJ is usually set at a low pressure in the initial stage and at a high pressure after a certain period of time.

[Problem to be solved by the invention]

In each of the above manufacturing methods, the process of forming the steel for the outer layer is different.
One is simply formed using copper foil σJ, and the other is formed using single-sided steel-clad laminated sheet metal.

In the method of forming the steel recesses for the outer layer by fully applying copper foil, the outer layer copper foil corresponding to the part of the laminate σ" I - circuit layer Q] where there is no circuit board copper foil is used. Depth is 5~
Linear depressions of approximately 18 μm σ are likely to occur. Next, the explanation will be given. In Fig. 6, a laminated board 5 having an inner layer circuit 4 on the screen is provided with outer I-copper foil on both sides through a prepreg layer 3. It occurs on the foil, and the 70th occurrence position 11 corresponds to the part where the copper foil of the circuit board is difficult to find within 1h.

It is very economical to simply use 0-layer copper foil as the copper foil for the outer layer, but if powder-like depressions occur in the outer layer copper foil, it may be impossible to form an outer pattern, and multi-layer Convenient use as a printed board 1 @ r! The purpose is to provide a method for forming copper-silver laminates (IJ!A).

[vl, σ to solve the problem] Means In order to achieve the above objective 7, in the present invention.

A prepreg layer is provided between the n4-layer board on which the inner layer circuit is formed, the outer layer copper foil, and σ, and among the prepregs J-σj, the prepreg in contact with the outer copper foil is heated at a heating rate of 6°C/min to the lowest melt viscosity of σ. 2000-3000 voice σ side resin assembly, heating rate 3 for the prepreg in contact with the laminate plate on which the inner layer circuit was formed.
Lol in °C/min) Minimum melt viscosity less than 1500 boisσ
] Resin must be used at a rate of 7%.

[Effect]

For the prepreg in contact with the outer copper foil 1C, a resin having a high minimum melting viscosity but having low σ, that is, low fluidity, is used. As the prepreg Vc in contact with the inner circuit 64 layer plate, σJ, which has high fluidity, is used. The prepreg in contact with the outer layer copper foil does not have root line depressions due to its low fluidity. However, under conditions where the fluidity is as low as 1%, there is a tendency for voids to occur in the prepreg layer.

To prevent this σj void phenomenon, the inner layer - path! It is better to use wood B ¥1, which has a relatively high fluidity, for the prepreg in contact with the j4-layer board.

As conditions for not producing linear dents in the outer layer copper foil and without producing voids in the prepreg layer, it is preferable that the prepreg in contact with the outer #4 copper foil has a minimum melting viscosity of 2000 to 3000 voids, and the inner layer has no surface lamination plate. The prepreg in contact with
Although it varies slightly depending on the inner N circuit residual steel ratio, it is preferably 1500 voids or less.

〔Example〕

Glass cloth (Nittobo Co., Ltd. WEA-116F) was impregnated with a flame-retardant epoxy resin varnish (NEMA, equivalent to FR4) so that the resin content was approximately 50%, and B-stage prepreg was obtained by varying the drying conditions. Ta.

The minimum melt viscosity of prepreg is pfr1 manufactured by Shimadzu! ! !
Using an elevated flow tester, a7φ×10ffiω
Nozzle/l/, 2-4 kg/at pressure, 80'C to 14
0℃! The temperature was then measured at a heating rate of 3°C/min.

The minimum melt viscosity of the obtained prepreg was 590,1050.
2250, 3100 boizuri 4m.

Next, in this Example 9'I1, the above-mentioned @ material was used for forming a steel clad laminate for a four-layer printed board shown in FIG.

Double-sided inner layer circuit formed steel clad laminate (copper foil thickness 70μm) 50
Thickness [], l a+mσ” prepreg A, B on both sides
The structure was arranged as shown in the diagram Ck, and an outer layer of 18 μm in thickness was formed for two sessions.

Figure 1 σノ#! As shown in Fig. 2, the four-layer printed boards 6 made by the above process are placed alternately with the stainless steel plates 7 between the press hot plates 9, and a shoe brush @8 is placed in contact with the hot plates to form the four-layer printed boards 6 under heat and pressure. The minimum melting viscosity and combinations of the prepregs σ used for prepregs A, B, and C' in FIG. 1 are shown in Table 1 above.

Table Note 1) Shows the number of sheets with linear dents when 8 sheets each of 4-layer T14 laminates for printed boards were manufactured.

In Conventional Examples 1 and 2, the viscosities of A, B, and CL:v were set to the same value by the conventional method. In Examples 1.2.3, the viscosity of A in contact with the outer layer copper foil was increased according to the present invention.

The CD viscosity in contact with the inner layer circuit laminate was lowered.

Table I shows the 4# printed board laminated board formed based on the above method.
Eight pieces each with 5 mVC shown as VC were obtained. The results of investigating the properties shown in Table 2 are shown.

[Invention σ] Effect] It can be clearly seen from Table 2 that the embodiment according to the present invention does not generate linear depressions, whereas the conventional example ``'C according to the conventional method generates linear depressions.However, As in Example 2, if the prepreg in contact with the laminated plate forming the inner layer enclosure does not easily flow, voids may occur, but under conditions where it easily flows as in Examples 1 and 2, voids do not occur.

[Brief explanation of drawings]

Figure 1 shows the 04-layer printed board before molding according to the present invention.
FIG. 2 is an example of laminated σJ paulownia formation, and FIG. 3 is an explanatory diagram of linear depressions in a conventional example. 1... Linear depression, 2... Outer layer steel amount. 3...Prepreg layer, 4...Inner layer circuit, 5...Laminated board, A, B, C
・・・・・・Prepreg. 6...4ff! 7 printed board, 7...
Stainless steel plate. 8...Kushi mushroom material, 9...Press heat sensitivity. Figure 3

Claims (1)

[Claims] 1. A prepreg layer is provided between the laminate on which the inner layer circuit is formed and the outer copper foil, and the prepreg in contact with the outer copper foil of the prepreg layer has a minimum melt viscosity of 2 at a heating rate of 3°C/min.
A copper-clad laminate characterized in that a resin with a minimum melt viscosity of less than 1500 voids at a heating rate of 3° C./min is used for the prepreg in contact with the laminate board on which the inner layer circuit is formed. Method of manufacturing the board.