JPH04186894A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a highly reliable high-density printed wiring board by forming a photosensitive resin film and photosensitive dry film layer on an insulating substrate after filling up a copper-plated hole with hole filling ink and exposing a prescribed wiring pattern by using a mask film brought into contact with the dry film layer, and then, etching a conductor layer after selectively removing the unexposed parts of the photosensitive resin film and photosensitive dry film layer. CONSTITUTION:After a hole is bored through an insulating substrate 2, a conductor layer 1 is formed and the through hole is filled up with hole filling ink 3 to both surfaces of the substrate 2. Then, after hardening the ink by irradiating the ink with ultraviolet rays and removing the ink 3 adhering to the conductor layer 1, a photosensitive resin film 5 is formed by applying and drying a liquefied photosensitive resin and a dry film layer 6 is formed by thermocompression bonding a dry film. Thereafter, etching resist films 6b and 6c are formed by exposing and developing a prescribed wiring circuit pattern through a mask film 4 and the exposed part of the conductor layer 1 is removed by etching by using the layers 6b and 6c as etching masks.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a through-hole printed wiring board having a high-density wiring circuit.

[Conventional technology]

Generally, through-hole printed wiring board (hereinafter referred to as T/HPWB)
It is called. ) As shown in Figure 2 (a) to (f),
The tenting method is often used, and according to this method, as shown in FIG. A photosensitive dry film layer (hereinafter referred to as a dry film layer) 6 is pasted on the film as shown in FIG. Burn the circuit pattern with ultraviolet light.

Next, unnecessary portions of the dry film layer 6 are removed using a developer to form the etching resist layer 6a as shown in FIG. 2(d).

Get 6b.

Furthermore, the exposed conductor layer 1 is removed by etching as shown in FIG.
), and finally the etching resist layers 6a and 6b are peeled off to form the wiring circuit 1b in FIG.
This is what you get.

In addition, in the hole filling method as shown in FIG. 3, a conductor layer 1 including a copper plating layer and a through hole 1a are formed on the insulating substrate 2 of FIG. 3(a). As shown in FIG. 3(b), the hole-filling ink 3 is filled and cured, and a dry film layer 6 is pasted on the surface of the insulating substrate 2, and as shown in FIG. Burn the wiring pattern with ultraviolet light.

Next, unnecessary portions of the dry film layer 6 are removed using a developer to form the etching resist layer 6b shown in FIG. 3(e).

Get 6c.

Furthermore, the exposed conductor layer 1 is removed by etching as shown in FIG.
), and finally, the etching resist layers 6b, 6c and the hole-filling ink 3 are peeled off to form the third wiring circuit 1b.
The T/HPWB shown in Figure (g) is obtained.

In addition, in this method, instead of the etching resist layers 6b and 6c formed by the dry film layer 6, images formed by screen printing are used as the etching resist layers 6b and 6c.
It can also be used as c.

[Problem to be solved by the invention]

However, in the case of the tenting method, it is necessary to protect the inside of the through hole from the etching solution by putting the etching resist layer in a tenting state like the etching resist layer 6a in FIG. 2(d), so the through hole is covered with a dry film. It was necessary to completely cover the through-hole land (hereinafter referred to as T/H land) lc with a larger diameter than the large diameter shown in FIG. 2(f). In addition, in large-diameter through holes, the etching resist may crack or lift due to spray pressure etc. during the etching process, causing through holes la and T/H lands 1c.
There was a problem in that it was not possible to protect the copper connections and through-hole lands.

Furthermore, in recent years, as the wiring circuit 1b has become denser, the T/H land 1c has become smaller, making it difficult to form the through hole 1a by the tenting method.

On the other hand, in the hole-filling method, after copper plating, the inside of the through-hole is filled with hole-filling ink 3 as shown in Figure 3(b).
Although there is an advantage that the T/H land size can be reduced to the same level as the hole diameter, the recesses due to surface scratches and dents on the conductor layer 1 shown in Fig. 3(b) cannot be covered by the Radry film layer. However, this method was not suitable for manufacturing T/HPWBs having high-density wiring circuits because wire breakage was likely to occur during the etching process. In addition, Fig. 3 (b), (c
), if poor adhesion occurs with the hole-filling ink 3 in the through-hole, the etching resist layer will crack or lift due to spray pressure etc. during the etching process, and the connection between the through-hole and the wiring circuit or the through-hole will be damaged. There was a problem that the copper inside the hole could not be protected.

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

[Means to solve the problem]

The method for manufacturing a printed wiring board of the present invention includes the steps of: drilling a hole in a copper-clad insulating substrate; forming a copper plating layer on the hole in the insulating substrate and on the surface of the insulating substrate; and forming the copper plating layer. a step of applying hole-filling ink to the hole formed and on the insulating substrate, and filling the hole-filling ink into the hole in which the copper plating layer is formed; and after curing the hole-filling ink by heat or UV curing, a step of polishing away the hole-filling ink on the surface to expose the copper plating layer; a step of applying a photosensitive liquid resin to the surface of the copper plating layer and then drying it to form a photosensitive resin coating; A step of heat-pressing a photosensitive dry film layer on the photosensitive resin coating film, and a step of contacting a mask film on the photosensitive dry film layer to expose a predetermined wiring circuit pattern, and then developing it so that it is not exposed to light. a step of selectively removing the photosensitive dry film layer and the photosensitive resin coating film (a coating film obtained by coating and drying a photosensitive liquid resin) of the portion, and a step of removing by etching the mesh portion exposed by development. Further, a wiring circuit is obtained, further comprising the step of removing the remaining photosensitive dry film layer, the photosensitive resin coating, and the hole-filling ink in the holes.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) to 1(i) are cross-sectional views showing the steps of a manufacturing method according to an embodiment of the present invention.

First, as shown in FIG. 1(a), a hole is bored in an insulating substrate 2, and then a conductor layer 1 is formed. The material of the insulating substrate 2 is as follows:
For example, a glass cloth-based epoxy resin plate or a glass-based polyimide resin plate can be used.

Next, as shown in FIG. 1(b), hole-filling ink 3 is filled in the through holes between the entire surface of the insulating substrate 2, and the insulating substrate 2 is
Both surfaces are irradiated with ultraviolet rays of 1 to IOJ/cn to be cured. When using a thermosetting type of hole-filling ink 3, the temperature is 80 to 140℃ to cure the hole-filling ink 3.
Dry and cure for 30 to 120 minutes.

Next, as shown in FIG. 1(c), the hole-filling ink 3 adhering to the conductive layer 1 is removed using an abrasive material such as a puff or sandpaper to expose the copper surface.

Next, as shown in FIG. 1(d), a photosensitive liquid resin is applied by a roller coating method and dried at 50 to 150°C to form a photosensitive resin coating 5.

Next, as shown in Figure 1(e), the dry film was heated to 80°C.
The dry film layer 6 is formed by thermocompression bonding at ~120°C.

Furthermore, as shown in FIG. 1(f), a predetermined wiring circuit pattern is printed through the mask film 4 by exposure.

Next, as shown in FIG. 1(g), it was developed with a developer such as an aqueous solution of sodium carbonate to obtain Eratin Breath J16b.

Form 6c.

Next, as shown in FIG. 1(h), an etching resist layer 6b is formed.
, 6c as an etching mask, the exposed portion of the conductive layer 1 is etched away.

Finally, as shown in FIG. 1, the etching resist layer 6b,
6c, the photosensitive resin coating 5 and the hole-filling ink 3 are removed using chemicals or the like to obtain T/HPWB.

In addition, in Fig. 1(d), in addition to the roller coating method,
A spray coating method or a curtain coating method can be used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, copper plating holes are filled with hole-filling ink, and a photosensitive resin coating and a photosensitive dry film layer are further formed on the surface of the insulating substrate.
After exposing a predetermined wiring pattern to light using a mask film, etching the conductor layer by selectively removing the photosensitive resin coating and photosensitive dry film layer in the unexposed areas allows (a) Tentin mites to be removed. T that was impossible under the law
/H The land width can be reduced. (B) Even large diameter through holes can protect the connection between the through hole and the land and the copper inside the through hole by sufficiently withstanding spray pressure etc. during the etching process. ) Since the concave parts caused by scratches and dents on the surface can be smoothed with the photosensitive resin coating, disconnections during the etching process can be significantly reduced. (d) Hole-filling ink and photosensitive resin coating filled in the through holes. The adhesion between the through-hole and the land has the effect of sufficiently protecting the connection between the through-hole and the land and the conductive layer inside the through-hole, thereby making it possible to manufacture highly reliable high-density printed wiring boards.

[Brief explanation of the drawing]

FIGS. 1(a) to (i) are cross-sectional views showing the manufacturing method of an embodiment of the present invention in the order of steps, and FIGS. 2(a) to (f)
1A and 1B are cross-sectional views illustrating an example of a method for manufacturing a printed wiring board using a conventional tenting method in the order of steps; FIG. 1...Conductor layer, 1a...Through hole, 1b...Wiring circuit, 1c...Through hole land, 2...Insulating substrate , 3...
・Hole filling ink, 4...Mask film, 5.
... Photosensitive resin coating film, 6 ... Dry film layer, 6a ... Etching resist layer in tenting state, 6b ... Etching resist of wiring circuit part Layer 6c... Etching resist layer on the through hole. Agent Patent Attorney Uchihara Oto No. 1 ml j j L, 1
jf Tato Shomaru tttit Figure 2/ Figure 26 Figure 3

Claims (1)

[Claims] a step of drilling a hole in a copper-clad insulating substrate, a step of forming a copper plating layer on the hole of the insulating substrate and the surface of the insulating substrate, and filling the hole in which the copper plating layer is formed and the hole on the insulating substrate. A step of applying ink and filling the hole-filling ink into the hole in which the copper plating layer is formed, and after curing the hole-filling ink with heat or UV curing, polishing and removing the hole-filling ink on the surface of the insulating substrate. a step of exposing the copper plating layer, a step of applying a photosensitive liquid resin to the surface of the copper plating layer and drying it to form a photosensitive resin coating, and applying a photosensitive liquid resin on the photosensitive resin coating film. A process of thermocompression bonding a dry film layer, and a mask film is brought into contact with the photosensitive dry film layer and a predetermined wiring circuit pattern is exposed to light, and then the unexposed portions of the photosensitive dry film layer and the photosensitive film are developed. A step of selectively removing the resin coating film (a coating film formed by coating and drying a photosensitive liquid resin), a step of etching away the copper portion exposed by development, and a step of removing the remaining photosensitive dry film layer. A method for manufacturing a printed wiring board, comprising the step of removing the photosensitive resin coating film and the hole-filling ink in the holes to obtain a wiring circuit.