JPS60107894A - 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 (Technical Field) The present invention relates to a method of manufacturing a multilayer printed wiring board having inner layers and patterns.

(Prior Art) At present, as printed circuit boards are required to have high-density packaging, this demand is met by increasing the number of inner layers at the same time as increasing the wiring density. Although 8 to 12 layers of multilayer printed wiring boards are currently being mass-produced, it is estimated that an increase in the number of layers will be required in the future.

As shown in Fig. 1, the conventional method for producing a multilayer printed wiring board is to use a copper-clad laminate 1 having a plurality of /IP turns and a copper foil 2 for the outer layer as adhesive base materials for multilayer printed wiring boards (hereinafter referred to as ZOLIZOLEG). It is usually manufactured by thermocompression bonding through 3. The thickness of the materials used for this is 0.1 mm or more for the insulating layer of the copper-clad laminate l of the inner layer pattern, and 0.03 mm for the copper foil.
5 to 0.07 tran, and the outer layer copper foil 2 is 0.00
9~0.035 tone, Norigreg 3 is 006~0.2t
tm is used, and 1 to 3 of Grerug 3 are used together.

The average thickness of multilayer boards made by thermocompression bonding is 2.4mm for 8 to 12 layers, and about 3mm for 14 or more layers.
It will be about m+. Furthermore, as the number of calendars increases, the thickness of the plate becomes thicker. This increase in thickness is unavoidable due to the increase in the number of copper-clad laminates 1, but the problem is the increase in the number of ZOLLEGs 3.

That is, the Chisolesleg 3 differs depending on the shape of the pattern on the surface to be adhered, and the thicker the copper foil and the smaller the area of copper remaining along the pattern, the thinner the Gresoleg 3 and the need to increase the number of sheets. This is to fill in the etched portions other than the d' turns of the resin molecules contained in Glycyleg 3. In this way, the thickness of the prepreg 3 is determined by the state of the copper foil on the contacting surface, so it is impossible to select the free life thickness, and the thickness is unavoidably increased. This means that the connectivity between the middle layer of a multilayer printed wiring board and through-hole plating and the reliability of through-hole plating largely depend on the board thickness, and as the board thickness increases, the difference in expansion coefficient between the insulating material and the through-hole copper plating increases. There is a drawback that reliability is poor because the absolute value of expansion and contraction becomes large.

(Objective of the Invention) The present invention solves the above-mentioned drawbacks and provides a novel processing method that is superior in reliability to conventional methods by making a multilayer printed wiring board thinner.

(Structure of the Invention) The present invention applies insulating resin to the parts other than where the pattern is formed to slightly reduce the unevenness of the copper foil of the pattern, and fills most of the four parts with the resin from Grishireg. This eliminates the need for silipregs and allows you to select any desired thickness of silicone preg in advance.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings. FIGS. 2(a) to (Q) are explanatory diagrams showing each step of the manufacturing method of the present invention. As shown in the figures, first, a conductor is placed on a copper-clad laminate 1 in which copper foil 1a is provided on the front and back sides of an insulating layer 1b.・Coat only the pattern with photoresist 11 (Figure (a)), and spray-etch it at 40°C with a copper foil etching solution, such as a ferric chloride aqueous solution (specific gravity 40°Be). Remove C (Figure b)). Next 7 otoresist 1
1 before washing 1114 ((C) figure). Next, the insulating resin 12, for example, Tsurugo resist ink, is applied to the recesses other than the key marks using a coating device such as a curtain coater, and then treated in a dryer at approximately 130°C for 30 minutes ((d) )figure). As shown in Fig. 3(e), the required number of middle layer plates (approximately 1 plate) are stacked with silicon preg 3 interposed between them, and the copper foil 2 is stacked on the outermost layer, followed by thermocompression bonding.

In this way, a multilayer printed wiring board according to the invention is obtained.

(Effects of the Invention) According to the present invention, in contrast to the conventional example described above, it is now possible to reduce the number of grid legs to one instead of the conventional method of using two or more. Multilayer printed wiring boards can be made thinner. The effect is particularly great for multilayer printed wiring boards with 10 or more layers, and multilayer printed wiring boards can be made with the minimum thickness that satisfies the strength requirements of printed wiring boards. Therefore, the connectivity with the middle layer copper foil is improved, and at the same time, it is possible to manufacture a product that is lighter than before.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional method for manufacturing a multilayer printed wiring board, and FIGS. 2(a) to (e) are explanatory diagrams showing an embodiment of the method for manufacturing a multilayer printed wiring board of the present invention. No...Copper-clad laminate, 1a...Copper foil on the rig turn part, 1
1]... Insulating layer, 2... Outermost copper foil, 3... Prepreg, 1... Photoresist, 12... Insulating resin. Figure 2''-2

Claims (1)

[Claims] A desired pattern is formed on the copper foil of the copper-clad laminate by etching, and the copper foil is superimposed on the outermost layer via an adhesive base material for multilayer printed wiring boards and bonded under heat to form a multilayer printed wiring board. A method for manufacturing a multilayer printed wiring board, comprising the step of applying an insulating material to the etched portions of the copper-clad laminate having a desired pattern formed thereon, as well as to the copper foil portions that are not etched.