JP2633424B2 - Manufacturing method of printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a high-density, high-precision printed wiring board.

[0002]

2. Description of the Related Art Generally, a printed wiring board (hereinafter, referred to as PWB) has a resin layer having an insulating property called a solder resist (hereinafter, referred to as SR) on a surface thereof. In the production of printed wiring boards, a liquid SR ink containing a photocurable resin as a main component is often used. According to this method, as shown in FIG. After forming the conductor pattern including 1
As shown in FIG. 4B, the liquid S having a viscosity range of 1 to 400 ps.
The R ink 2 is applied to the entire surface of the substrate 12 including the through hole 1 for front and back conduction by a bar coating method, a screen printing method, a roll coating method, a spray coating method, a curtain coating method, or the like.
70 to 100 g per ² m ² , 70 to 100 g
Dry at 5 ° C. for 5 to 40 minutes to form a semi-cured photosensitive layer. Next, as shown in FIG.
After exposing a predetermined SR pattern with UV light 5 through the above, the unexposed portion is removed with a developing solution,
Heat treatment at 20 ° C. for 20 to 90 minutes, as shown in FIG.
SR pattern 6 was obtained.

[0005] In a PWB which does not require high density and high precision, as shown in FIG. 5A, after a conductor pattern including a through hole 1 for front and back conduction is formed on a substrate 12, FIG.
As shown in (b), the liquid SR ink 2 is applied to one surface of the substrate 12 including the through holes 1 for front / back conduction at a rate of 70 to 100 / m ^2.
The composition is applied by a bar coating method, a screen printing method, a roll coating method, a spray coating method, a curtain coating method at a ratio of g, and dried at 70 to 100 ° C. for 5 to 40 minutes to form a semi-cured photosensitive layer. Next, as shown in FIG. 5C, a predetermined pattern is exposed to UV light 5 through a mask film 3 and an unexposed portion is removed with a developing solution. Then, as shown in FIG. Get. Further, as shown in FIG.
The amount of the liquid SR ink 2 applied to the opposing surfaces is 1.1 to 1.
Three times the amount of the liquid SR ink 8 is applied by a bar coating method, a screen printing method, a roll coating method, a spray coating method, a curtain coating method or the like, and dried at 70 to 100 ° C. for 5 to 40 minutes to obtain a semi-cured state. Form a photosensitive layer. At this time,
Since the application amount is 1.1 to 1.3 times the application amount, the through hole 1 for front and back conduction is closed without bursting of the liquid SR ink 8 due to thermal expansion of the air inside. Next, FIG.
As shown in (b), a predetermined pattern is formed through the mask film 4 so that the exposure amount of the UV light 5 is 1.1 to 1.3 times the amount of UV light.
After exposing with light 10 and removing unexposed portions with a developing solution,
A heat treatment is performed at 20 to 160 ° C. for 20 to 90 minutes, and FIG.
As shown in (c), the SR pattern 11 was obtained.

[0004]

In this conventional method of manufacturing a PWB, the through hole for front and back conduction cannot be completely closed, and the solder rises to the mounting surface side in the soldering after the component is mounted, and the bridge is formed. That the solder rises through the through-holes for front-to-back conduction and makes thermal shock by contacting the component; generates a solder bridge between the adjacent through-holes for front-to-back conduction; There are problems such as the occurrence of solder bridges between them, and corrosion of residual residues such as flux in the through-holes for front-to-back conduction, causing electrical failure, and the like. Although the through hole for conduction can be closed,
There is a problem that a high-density, high-precision SR pattern cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a thermal shock to a bridge and a component when a solder rises on a component mounting surface, a bridge between a front and a back conductive through hole, and a front and a back. It is an object of the present invention to provide a method for manufacturing a PWB that prevents a corrosive substance from entering a through hole for conduction.

[0006]

According to the method of manufacturing a printed wiring board of the present invention, a step of forming a conductor pattern including through holes for front and back conduction on a substrate and a step of applying a photocurable liquid solder resist ink on both surfaces are performed. Forming a predetermined solder resist pattern by removing a non-exposed portion of the photocurable liquid solder resist ink by abutting a mask film and developing after exposure, and one surface at a time on a substrate including the solder resist pattern. A step of applying the photocurable liquid solder resist ink again, and a step of removing the unexposed portions by developing after exposing only the front and back conduction through holes that require the obstruction of the front and back conduction through holes, and thereafter The method includes a step of closing a hole of the front-back conduction through-hole requiring the closing by thermosetting.

[0007]

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

FIGS. 1 (a) to 1 (d), 2 (a) to 2 (c)
3 (a) to 3 (c) are cross-sectional views shown in the order of steps for explaining one embodiment of the present invention.

First, as shown in FIG. 1A, a conductor pattern including a through hole 1 for front and back conduction is formed on a substrate 12.

Next, as shown in FIG.
A 400 ps liquid SR ink 2 is applied to the entire surface of the substrate 12 at a rate of 7 / m ² by a bar coating method, a screen printing method, a roller coating method, a spray coating method, a curtain coating method, or the like.
It is applied at a rate of 0 to 100 g, and 5 to 4 at 70 to 100 ° C.
Dry for 0 minutes to form a semi-cured photosensitive layer.

Next, as shown in FIG. 1C, a predetermined SR pattern is exposed to UV light 5 through the mask films 3 and 4, and the unexposed portions are removed with a developing solution. Thus, the SR pattern 6 is obtained.

Further, as shown in FIG.
400 ps of the liquid SR ink 2 is applied on one side by a bar coating method, a screen printing method, a roll coating method, a spray coating method, a curtain coating method, etc.
Dry at 0 ° C. for 5-40 minutes.

Thereafter, as shown in FIG. 2 (b), after exposing with UV light 5 through a mask film 7 which shields the portions other than the front and back conduction through holes 1 which need to be closed, the unexposed portions are developed with a developing solution. Then, as shown in FIG. 2C, an SR pattern 6 for closing the front and back conductive through holes 1 is obtained on one surface.

Next, as shown in FIG.
At 400 ps, the application amount of the liquid SR ink 2 is 1.1 to 1.
A triple amount of the liquid SR ink 8 is applied on the other surface by a bar coating method, a screen printing method, a spray coating method, a curtain coating method or the like, and dried at 70 to 100 ° C. for 5 to 40 minutes.

Thereafter, as shown in FIG. 3 (b), after exposing with UV light 10 through a mask film 9 which blocks light except for the front and back conduction through holes 1 which need to be closed, an unexposed portion is removed. A heat treatment is performed at a temperature of up to 160 ° C. for 20 to 90 minutes to obtain an SR pattern 11 for closing the front and back conduction through holes 1 on the other surface as shown in FIG.

In FIG. 3B, the mask film 9 in FIG. 2B can be used as the mask film 9. In addition, exposure can be performed with an electron beam instead of UV light.

[0017]

As described above, according to the present invention,
High-precision, high-density PWB through-holes for front-to-back conduction can be completely closed, so that soldering after mounting components can prevent bridges due to solder rise.
It can prevent the solder from rising through the front and back conduction through-holes and coming into contact with the parts to give a thermal shock, prevent solder bridging between adjacent front and back conduction through-holes, and ingress of corrosive substances into the front and back conduction through-holes And the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view shown in the order of steps for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view shown in the order of steps for explaining an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the order of steps for explaining one embodiment of the present invention.

FIG. 4 is a cross-sectional view shown in a process order for explaining an example of a conventional PWB manufacturing method.

FIG. 5 is a cross-sectional view shown in the order of steps for explaining another example of the conventional PWB manufacturing method.

FIG. 6 is a cross-sectional view shown in the order of steps for explaining another example of the conventional PWB manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Through hole for front and back conduction 2,8 Liquid SR ink 3,4,7,9 Mask film 5,10 UV light 6,11 SR pattern 12 Substrate

Claims (1)

(57) [Claims] 1. A step of forming a conductor pattern including through holes for front and back conduction on a substrate, a step of applying a photo-curable liquid solder resist ink on both surfaces, and a step of contacting a mask film and developing after exposure by the photo-curing. Forming a predetermined solder resist pattern by removing the unexposed portions of the liquid solder resist ink, and applying a photocurable liquid solder resist ink again on each side of the substrate containing the solder resist pattern again The step of removing the unexposed part by development after exposing only the front and back conduction through-holes that need to close the inside of the front and back conduction through-holes, and then removing the unexposed portions by thermal curing of the front and back conduction through-holes that need to be closed A method for manufacturing a printed wiring board, comprising closing a hole.