JPH0213476B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing multilayer printed wiring boards.
In particular, a catalyst-containing resin is formed on the inner layer substrate,
The present invention relates to a method for manufacturing a multilayer printed wiring board on which an outer layer circuit pattern is formed.

BACKGROUND ART A conventional method for manufacturing a multilayer printed wiring board will be explained with reference to FIG.

Figure a shows an inner layer substrate 1 in which copper foil 3 is bonded to both surfaces of an epoxy resin 2. Figure b shows a step in which the copper foil 3 of this inner layer substrate 1 is etched to form a pattern 4, and Figure c shows a process in which the inner layer substrate 1 is placed in the center in order to form a multilayer printed wiring board. Figure d shows the process of placing pregregs 5 on both sides, and then laminating an outer layer substrate 6 made of epoxy resin 2 to which copper foil 3 is bonded as an outer layer, and integrating by heating and pressurizing. Drill through holes 8 at predetermined locations on the multilayer laminate 7.
In figure e, seeder 9 treatment is performed for activation in chemical plating process, in figure f chemical plating 10 is formed by thin chemical plating process, and in figure g the plating resist printing 11 is performed. Then, copper plating 12 is applied as shown in Figure H, the plating resist 11 is removed as shown in Figure I, and etching is performed as shown in Figure J to form circuit patterns 13 and through holes 14. Conventionally, the multilayer printed wiring board 15 is manufactured through the above steps.
was being produced.

Further, in Japanese Patent Publication No. 50-1424, a multilayer wiring board using a catalyst-containing substrate is proposed, but it is manufactured by heating and pressing two substrates.

Problems to be Solved by the Invention Conventional multilayer printed wiring requires a large number of steps as described above, and in particular, the heating and pressing step when integrating using pre-regs is large-scale and troublesome. Also,
During the drilling process for through-holes, the epoxy resin 2 melts due to the heat of over 400°C generated during cutting with a drill, and some of it stains the surface of the copper foil 3, impairing the electrical insulation properties of the through-holes. There were times when it was lowered.

The present invention provides a manufacturing method for manufacturing a multilayer printed wiring board without performing such a heating and pressing step.

Means for Solving the Problems The method for manufacturing a multilayer printed wiring board of the present invention uses an insulating board containing a catalyst as a base material, and an inner layer base material coated with an adhesive containing a catalyst on both sides of this base material. Drill holes for through holes, form a plating resist layer, immerse the board in an electroless plating bath to form an inner layer circuit pattern, apply catalyst-containing epoxy resin, and apply the outer layer plating resist again. After forming a layer, the substrate is immersed in an electroless plating bath again to form an outer layer circuit pattern and through holes.

Function The present invention is a manufacturing method that can manufacture a multilayer printed wiring board by coating without any press work, so the process is simplified and work efficiency is improved compared to conventional manufacturing methods.

Example An embodiment of the present invention will be described based on FIG.

21 is a glass epoxy resin base material having catalytic properties in an electroless plating bath. The base material 21 is made by impregnating a glass cloth or paper with an epoxy resin varnish containing a bisphenol A type epoxy or a phenol novolak type epoxy as a main ingredient, using a dicyanamide or imidazole compound as a hardening agent, using a glass cloth or paper as a core material. A plurality of sheets of glass cloth (or paper) are laminated and then heated and pressed to produce an insulating plate.

This base material 21 coated with catalyst-containing adhesive 22 on one or both sides is used as the inner layer substrate 23, and is manufactured by the following steps (Figure a).

(a) A drilling step (Figure b) of drilling a through hole 24 for a through hole into which an electronic component is inserted at a predetermined location of this inner layer substrate 23.

(b) A reverse pattern plating resist application step in which areas on one or both sides of this substrate 23 where no circuit pattern is provided are coated with an epoxy resin 25 that does not have catalytic properties in an electroless metal plating bath. (Figure c).

This non-catalytic epoxy resin is a material that does not contain palladium, uses a dicyandiamide or imidazole compound as a curing agent, and uses a bisphenol A type epoxy or a phenol novolac type epoxy as a material.

(c) This board is immersed in a known electroless metal plating bath, and electroless copper is applied to the inner layer circuit pattern on which the reverse pattern plating resist 25 is not applied and the inner wall portion 26 for the through hole formed in the board. Electroless copper plating step (d) in which plating 27 is formed by precipitation
figure).

(d) A catalyst-containing epoxy resin application step (e
figure).

This catalyst-containing epoxy resin 28 uses dicyandiamide and imidazole compounds as a curing agent,
Fine grained inorganic fillers (alumina,
Palladium is adsorbed onto aluminum silicate.

(e) A reverse pattern plating resist application step (Figure f) in which printing is performed to form a plating resist layer again using a non-catalytic epoxy resin 29 on the epoxy resin 28 layer.

(f) An electroless copper plating step (g
figure).

The multilayer printed wiring board of the present invention is manufactured through the above steps. In the above manufacturing method, a three-layer or four-layer circuit pattern was formed, but in addition (4) to
By repeating the step (6), it is possible to obtain a multilayered printed wiring board.

Effects of the Invention The present invention is a method for manufacturing a multilayer printed wiring board as described above, and conventionally, the through-holes are formed after laminating multiple layers, so a drill must be used to make the holes. It was necessary to remove the dirt caused by the epoxy resin melting due to the heat at dawn, but in the case of the manufacturing method of the present invention, no metal part is exposed in the through-hole area, so this problem is avoided. This does not occur, and since the holes are made in the first step in the inner layer substrate, the holes can be made with a punch without using a drill, so the holes can be completed in one operation using a press, which is efficient. Additionally, since the process is shorter than in conventional multilayer printed wiring board manufacturing methods, the defect rate is also reduced and productivity is dramatically improved.

Furthermore, unlike the press method (laminate method), since a coating method is used, there are no cavities in the inner layer circuit pattern, and there is no deterioration of the wiring board due to processing distortion, so the electrical properties are improved. An excellent and highly reliable multilayer printed wiring board can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the steps of a conventional manufacturing method, in which figure a is a cross-sectional view of the inner layer substrate, figure b is a cross-sectional view after etching, figure c is a cross-sectional view of the integrated lamination, and figure d is a cross-sectional view of the inner layer substrate. A cross-sectional view showing the hole drilling process, figure e is a cross-sectional view after seeder treatment and the inside is omitted, figure f is a cross-sectional view after chemical plating treatment, figure g is a cross-sectional view after plating resist treatment, figure h is a cross-sectional view after electrolytic copper plating. Figure i is a cross-sectional view after the plating resist has been removed, Figure J is a cross-sectional view after the etching process, Figure 2 is a cross-sectional view for explaining the manufacturing method of the present invention,
The figure is a cross-sectional view of the inner layer substrate, figure b is a cross-sectional view after hole-drilling processing, figure c is a cross-sectional view after reverse pattern printing process, figure d is a cross-sectional view after electroless copper plating process, and figure e
The figure is a cross-sectional view after coating with catalyst-containing resin, the figure f is a cross-sectional view after reverse pattern printing, and the figure g is a cross-sectional view after electroless copper plating. In the figure, 21 is an insulating substrate, 22 is a catalyst-containing adhesive, 23 is an inner layer substrate, 24 is a hole, 25 is reverse pattern mask printing, 26 is an inner wall of a through hole,
27 is electroless copper plating, 28 is a catalyst-containing epoxy resin, 29 is a non-catalytic resin, 30 is a circuit pattern, and 31 is a through hole.

Claims (1)

[Scope of Claims] 1. An inner substrate having an insulating plate containing a catalyst that has catalytic properties in an electroless metal plating bath as a base material, and an adhesive containing a catalyst coated on one or both sides of this base material. A method for manufacturing a multilayer printed wiring board, characterized in that it is manufactured using the following steps. (a) A hole-drilling process in which holes for through-holes are drilled at predetermined locations on this inner layer substrate. (b) A reverse pattern plating resist application step in which areas on one or both sides of this inner layer substrate where no circuit pattern is provided are coated with a material that does not have catalytic properties in an electroless metal plating bath. (c) This substrate is immersed in an electroless metal plating bath, and electroless metal plating is deposited and formed on the areas where the reverse pattern plating resist is not applied and on the inner walls of the drilled through holes. Plating process. (d) Catalyst-containing epoxy resin application process in which catalyst-containing epoxy resin is applied to the front surface except around the through-holes. (e) A reverse pattern plating resist application process in which areas on the surface of the catalyst-containing epoxy resin where no circuit pattern is to be provided are coated with a material that does not have catalytic properties in an electroless metal plating bath. (f) Electroless copper plating in which this substrate is immersed in an electroless metal plating bath again, and electroless metallic copper is deposited and formed in the areas where the reverse pattern plating resist is not applied and in the through holes. Process.