JPH02196494A - Manufacture of printed wiring board for surface mounting - Google Patents

Abstract

PURPOSE:To prevent a through-hole from being broken down and simply form even a landless through-hole by preventing an electro-deposition film in the through-hole from being exposed to light even it a film is displaced upon UV exposure by filling the through-hole with a conductive ink material prior to the formation of the electro-deposition film. CONSTITUTION:A through-hole is formed though a glass epoxy double-side copper laid laminate sheet 1, and a copper plated layer 3 is formed over the entire surface of the laminate sheet 1 including a hole wall. Then, the through-hole 2 is filled with conductive paste 4 as a hole filling ink material by screen printing, and thermally cured. After a positive type electro- depsition film 5 is formed, a non-used electro-deposition solution is removed through flowing water and the electro-deposition film 5 is cured by a hot-air drier. Successively, positive type pattern films 6a, 6b are brought into close contact with the electro-deposition layer 5 in vacuum and exposed to light by a UV exposure device, and thereafter dipped in soda, metasilicate to melt and remove the exposure portion. Thereafter, unnecessary copper plated layer and abase copper foil are melted and removed, and further the electro-deposition film 5 is separated and removed to form a through-hole printed wiring board. Upon the exposure, the throughhole 2 is not exposed to light, the through-hole is prevented from being broken down.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for manufacturing a printed wiring board for surface mounting, and more specifically, a through-hole printed wiring board for surface mounting using an electrodeposition method (photo-ED method). The present invention relates to a manufacturing method.

[Conventional technology]

According to the photo-ED method, first, a positive type photosensitive electrodeposited film is formed by electrodeposition on a substrate on which, for example, a copper plating layer is formed on the entire surface including the walls of the through holes. Then,
This electrodeposited film is exposed to ultraviolet light (UV) through a positive type film having a predetermined circuit pattern. Thereafter, the exposed portion of the electrodeposited film is removed by development, and the copper plating layer exposed on the surface and the underlying copper foil are further removed by etching. Then, the remaining electrodeposited film is removed.

[Problem to be solved by the invention]

A photosensitive electrodeposited film has better adhesion to a substrate than a dry film, so a higher density wiring pattern can be formed, but on the other hand, it has the following drawbacks.

That is, during UV exposure, if the inside of the through hole is exposed due to film shift, the electrodeposited film inside the through hole is removed during development, which may cause the through hole to break.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a surface mounting substrate having a through hole and a conductive film such as a copper plating layer on the entire surface including the hole wall of the through hole. After filling the interior with a conductive ink material, a positive-type photosensitive electrodeposited film is formed on the substrate by electrodeposition, and the twice-electrodeposited film is exposed to light through a positive-type film having a predetermined circuit pattern. After removing the electrodeposited film in the exposed portion to form an etching resist pattern, and removing the conductive film exposed in the exposed portion by etching, the electrodeposited film is removed.

〔Effect of the invention〕

As mentioned above, by filling the conductive ink material in the through holes prior to forming the electrodeposited film, even if the film shifts during UV exposure, the through holes will remain intact as before. The electrodeposited film is not exposed to light, so through-hole disconnection is prevented, and landless through-holes can be easily manufactured.

〔Example〕

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

First, as shown in Figure 1, the copper foil thickness is 18J11.
A through hole 2 with a hole diameter of 0.4a+m was bored in a glass epoxy double-sided copper-clad laminate 1 with a thickness of 1.0H, and the entire surface of the laminate 1, including the hole wall, was copper plated to a thickness of 25J! 1
A copper plating layer 3 was formed.

Next, a conductive paste 4 (silver or carbon made into fine particles and a thermosetting resin dispersed as a binder polymer 1) is used as a filling ink material in the through hole 2. For example, Tamura Kaken Carboroid CLX-20
4) was filled by screen printing and thermally cured at 180° C. for 15 minutes, and the remaining surface portion was removed by polishing with a puff (5600) (see Fig. 2).

As shown in Figure 3, an anionic electrodeposition solution (
After applying electrodeposition coating (50 mA/dm'', 25°C, 2 minutes) by dipping it in H-hon paint ■ Photo ED)'-1000) to form a positive type electrodeposition film 5, it was electrodeposited under running water. After removing the remaining electrodeposition liquid and draining the water, dry it in a hot air dryer.
The twice-electrodeposited film 4 was cured at 00° C. for 5 minutes.

Subsequently, as shown in FIG. 4, positive type pattern films 6a and 6b are vacuum-adhered onto the electrodeposited layer 5, and exposed to an integrated light amount of 350+ij/aJ using a UV exposure machine (Oak@HMW-680). After being exposed to no light, it was immersed in 1% sodium metasilicate at 30° C. for 1 minute to dissolve and remove the exposed portion (see FIG. 5).

After that, it was immersed in a ferric chloride aqueous solution with a specific gravity of 40 degrees Celsius and 50 degrees Celsius for 5 minutes to dissolve and remove the unnecessary copper plating layer 3 and the copper foil on the ground (see Figure 6), and then immersed in 3% caustic soda 5.
The electrodeposited film 5 was peeled off by immersion at 0° C. for 2 minutes to produce a through-hole printed wiring board as shown in FIG.

In this way, by filling the through holes 2 with conductive ink before forming the electrodeposited film 5, when there is no light, for example, as shown in FIG. Even if 6a is misaligned, the electrodeposited film within the through hole 2 is not exposed to light as in the conventional case, and thus through hole disconnection is prevented. Therefore, not only through-hole substrates can be manufactured with high yield, but also landless through-hole substrates can be manufactured.

[Brief explanation of the drawing]

1 to 6 are cross-sectional views of intermediate products in each step for explaining the manufacturing method of the present invention, and FIG. 7 is a cross-sectional view of a printed wiring board obtained by the present invention. In the figure, 1 is a double-sided copper-clad laminate, 2 is a through hole, 3 is a copper plating layer, 4 is ink (conductive paste), 5 is an electrodeposited film, and 6a and 6b are films. Patent applicant: ELNA Co., Ltd. Agent, Patent attorney: Takuya Ohara Atsushi Ivy Diagram → 143'. fig. fig. fig. fig.

Claims (1)

[Claims] (1) After filling a conductive ink material into the through hole of a surface mounting board having a through hole and having a conductive film on the entire surface including the hole wall of the through hole,
A positive type photosensitive electrodeposited film is formed on the above substrate, and the second electrodeposited film is exposed to light through a positive type film having a predetermined circuit pattern, and the exposed part of the electrodeposited film is removed to create an etching resist pattern. 1. A method for manufacturing a printed wiring board for surface mounting, which comprises forming a conductive film exposed in exposed areas by etching, and then removing the electrodeposited film.