JPH03272195A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To enable holes to be improved in position accuracy and miniaturized so as to make a wiring board high in wiring density by a method wherein a blind viahole is bored in a multilayer printed wiring board with laser rays when the multilayer printed wiring board provided with a blind hole is formed. CONSTITUTION:A through-hole 3 is bored in a base material 1 on which a copper foil 2 is pasted, the copper foil 2 is etched to form a circuit 4a, and an insulator layer 5 of epoxy insulating resin is formed on the whole surface through a screen printing method excluding the through-hole 3. Then, an adhesive layer 6 formed of additive adhesive agent is applied on the layer 5 through a screen printing method and hardened, the layer 6 is treated with a roughening liquid mainly composed of CrO3 100g/l and H2SO4 300ml/l to turn into a roughened face 7, and a blind hole 8 is provided to a part where a blind viahole is formed by the irradiation with laser rays. Then, a resist layer 10 is provided to the whole surface through the intermediary of a catalyst 9, a copper plating layer 11 is formed on a part other than the layer 10 through a thick electroless plating method, and a viahole 12, a through-hole 14, and a prescribed circuit 4b are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer printed wiring board, and particularly to a method for manufacturing a multilayer printed wiring board having non-through holes.

[Conventional technology]

A conventional method for manufacturing this type of multilayer printed wiring board will be described below with reference to FIG.

First, as shown in FIG. 3(a), a through hole 3 is formed by drilling a hole in the base material 1 on which the copper foil 2 is laminated.

Next, as shown in FIG. 3(b), the copper foil 2 is etched using a conventional method to form a circuit 4a.

Next, as shown in FIG. 3(c), an insulator layer 5 is printed and formed using a screen printing method, excluding the through holes 3 and non-through holes that will be connection parts with the upper layer conductor.

Next, as shown in FIG. 3(d), an adhesive layer 6 is applied onto the insulating layer 5 by screen printing.

Next, as shown in FIG. 3(e), the surface is roughened to obtain a roughened surface 7 of the adhesive layer.

Next, as shown in FIG. 3(f), the entire surface is subjected to catalyst treatment and a catalyst 9 is deposited.

Next, as shown in FIG. 3(g), panel copper plating is performed to form a copper plating layer 1-1, thereby forming blind via holes 12 and through holes 14.

Next, as shown in FIG. 3(h), the photomask 15 is aligned and a normal circuit is formed.

Next, as shown in FIG. 3(i), a circuit 4b is provided in the outermost layer.

Finally, as shown in FIG. 3 (j>), a solder resist 13 is formed to obtain a predetermined multilayer printed wiring board.

[Problem to be solved by the invention]

The conventional multilayer printed wiring board manufacturing method described above had the following drawbacks.

(1) Since the non-through holes that will become blind via holes are formed using the screen printing method, the positional accuracy of the blind via holes depends on the screen alignment accuracy, but since the screen alignment accuracy is not good, it is necessary to make the blind via holes larger in design. This is an obstacle to high-density wiring.

(2) Due to the characteristics of the screen printing method itself when forming the insulating layer, it is not possible to form blind via holes with a small diameter of 0.5 mm or less, which hinders high-density wiring.

An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board that allows high-density wiring.

[Means to solve the problem]

The present invention includes a step of providing a through hole in a base material covered with copper foil;
a step of forming a circuit by a normal construction method, a step of forming an insulator layer except for the non-through hole portion which becomes a connection portion between the through hole portion and the upper layer conductor, and forming an adhesive layer on the insulator layer. A multilayer printed wiring comprising a step of roughening the surface of the adhesive layer, and a step of plating the through holes, the non-through holes, and the surface of the adhesive layer to form predetermined circuits, through holes, and blind via holes. The method for manufacturing a board includes the step of drilling the insulating layer and the adhesive layer by irradiating the adhesive layer with a laser beam to form the non-through hole.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(j) are vertical cross-sectional views showing the manufacturing method of the first embodiment of the present invention in the order of steps.

In the first embodiment, first, as shown in FIG. 1 (a), a through hole 3 is provided by drilling a hole in a base material 1 on which a copper foil 2 is laminated.

Next, as shown in FIG. 1(b), the copper foil 2 is etched using a normal method to obtain a circuit 4a.

Next, as shown in FIG. 1(c), an insulator layer 5 is formed by screen printing except for 3 portions of the through holes. This insulator layer 5 is made of epoxy-based insulating resin, and the thickness of the insulator layer 5 is about 50 μm.

Next, as shown in FIG. 1(d), an adhesive layer 6 is applied onto the insulating layer 5 by screen printing and cured. For the adhesive layer 6, an additive adhesive is used.

Then, as shown in FIG. 1(e), (, rogl, o.

g/11, H2S O4300m (1/4
The roughened surface 7 of the adhesive layer is obtained by treating with a roughening liquid containing as a main component for 7 to 10 minutes.

Next, as shown in FIG. 1(f), a blind via hole 8 is formed by irradiating a laser beam onto the blind via hole forming area.

A carbon dioxide laser is used for the laser beam.

Next, as shown in Figure 1 (g), the entire surface is subjected to catalyst treatment,
A catalyst 9 is deposited.

Next, as shown in FIG. 1(h), a plating resist 10 is formed using a dry film.

Next, as shown in FIG. 1(i), a copper plating layer 11 is formed in addition to the plating resist by thick electroless copper plating, and blind via holes 12, through holes 14, and predetermined circuits 4b are formed.

Finally, as shown in FIG. 1(j), a solder resist 13 is applied by screen printing to obtain a multilayer printed wiring board having a predetermined circuit.

FIGS. 2(a) to 2(e) are cross-sectional views showing the manufacturing method of the second embodiment of the present invention in the order of steps.

In the second embodiment, first, as shown in FIG. 2(a), a non-penetrating hole 8 is formed using a laser beam using the same method as in the first embodiment, and then the entire surface is subjected to catalyst treatment, and a catalyst 9 is formed. to adhere to. Next, as shown in FIG. 2(b), a copper plating layer 11 is formed on the entire surface by panel plating, thereby forming blind via holes 12 and through holes 14.

Next, as shown in FIG. 2<c), a normal photomask 15 is
Perform alignment.

Then, as shown in FIG. 2(d), a predetermined number of times! , 4b.

Finally, a solder resist 13 is applied by screen printing to obtain a multilayer printed wiring board having a predetermined circuit.

〔Effect of the invention〕

As explained above, the present invention makes it possible to improve the positional accuracy and reduce the diameter of blind via holes by drilling with a laser beam when forming non-through holes for blind via holes, and to increase the density of wiring in multilayer printed wiring boards. There is an effect that can be done.

[Brief explanation of drawings]

FIGS. 1(a) to (j) are longitudinal cross-sectional views shown in the order of steps for explaining the manufacturing method of the first embodiment of the present invention, and FIG.
a) to (e) are longitudinal cross-sectional views shown in the order of steps for explaining the manufacturing method of the second embodiment of the present invention, and FIGS.
j) is a longitudinal cross-sectional view shown in the order of steps for explaining an example of a conventional method for manufacturing a printed wiring board. DESCRIPTION OF SYMBOLS 1... Base material, 2... Copper foil, 3... Through hole, 4a,
4b...Circuit, 5...Insulator layer, 6...Adhesive layer, 7...Adhesive layer roughened surface, 8...Non-through hole, 9...
・Catalyst, 1o... Plating resist, 11... Copper plating layer, 12... Blind via hole, 13... Solder resist, 14... Through hole, 15...
Photo mask.

Claims (1)

[Claims] A step of providing a through hole in a base material covered with copper foil, a step of forming a circuit using a normal construction method, and a step of forming an insulator layer excluding the non-through hole portion that will be the connection portion between the through hole portion and the upper layer conductor. a step of forming an adhesive layer on the insulator layer and roughening the surface of the adhesive layer; and plating the through hole, the non-through hole, and the surface of the adhesive layer to form a predetermined circuit and through-hole. A method for manufacturing a multilayer printed wiring board comprising a step of forming a hole and a blind via hole, the method comprising the step of drilling the insulating layer and the adhesive layer by irradiating a laser beam to form the non-through hole. A method for manufacturing a multilayer printed wiring board, characterized by: