JPH04145691A - Through hole formation - Google Patents

Abstract

PURPOSE:To reduce both cost and lead time by forming a through hole without using a metal fixture. CONSTITUTION:A resist layer 3 of dry film is formed on the surface of a green sheet 2 and masked so that other parts may be exposed, which exclude a through hole pattern section 5. Then, it is developed with a solvent 6 where the through hole section 5 is removed while the exposed part 4 is arranged to remain. It is further developed and the green sheet 2 is partially removed by way of the pattern section 5. The exposed part 4 of the remaining resist layer 3 is removed so that a thorough hole 7 may be formed. This construction makes it possible to shorten lead time at low cost since no mold is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a green sheet multilayer wiring board in which a plurality of green sheets are laminated and then fired all at once, and particularly relates to the formation of through holes for connections between conductor layers.

[Conventional technology]

FIGS. 2(a) to 2(c) are process explanatory diagrams showing a conventional technique for forming through holes.

Conventionally, this type of through hole has been formed using a mold as shown in FIG. In FIG. 2, the upper mold 11 is equipped with a narrow bottle 12, and the lower mold 13 is equipped with a narrow bottle 12.
A hole 14 is formed at a position corresponding to the hole 14, so that the bottle 12 and the hole 14 are engaged with each other. And upper mold 1
A green sheet 15 is placed between the green sheet 1 and the lower mold 13 as shown in FIG. (Figure 2(b).

(C)).

[Problem to be solved by the invention]

The above-described through-hole forming method using a mold requires a highly accurate mold. Therefore, the cost increases due to the cost of the mold. Furthermore, since it takes time to manufacture the mold, there is a problem in that the lead time becomes long. This is a big problem, especially in products produced in small quantities and in many varieties.

[Means to solve the problem]

The present invention provides a method for forming through holes in a green sheet multilayer wiring board in which a plurality of green sheets are laminated and then fired all at once, including a first step of forming a photosensitive resist layer on the surface of the green sheet, and a step of forming a photosensitive resist layer on the surface of the green sheet; a second step of exposing a through-hole pattern in the layer; a third step of removing a part of the green sheet together with the resist layer; and a fourth step of removing the remaining resist layer; For the resist layer, a dry film is used in which exposed portions are polymerized and remain after development.

C Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1<a) to f)- are process explanatory diagrams showing one embodiment of the present invention.

Although green sheet 2 is not shown in the diagram, first a binder (organic resin binder) and a solvent are added to the raw material inorganic powder, and the mixture is mixed and kneaded using a mixer, and the inorganic powder is uniformly dispersed in the solvent in which the binder is dissolved. Create a slurry.

Then, slurry is supplied onto the organic film 1 using a doctor blade method or the like so that the thickness becomes uniform, and the slurry is dried.

In this example, a mixed powder of alumina and lead borosilicate glass is used as an inorganic powder, PVB (polyvinyl butyral) is used as a binder, and an alcoholic solvent such as ethyl cellosolve is used as an organic solvent to form a green sheet 2 with a thickness of 50 μm. Formed on film 1 (Fig. 1(a))
.

First, a resist layer 3 is formed on the green sheet 2 (
Figure 1(b)). In this example, the resist layer 3 was formed using a dry film in which the exposed portions were polymerized and removed after development. Next, using a glass mask, a portion other than the through-hole pattern portion 5 where the through-hole is to be formed is exposed to light (FIG. 1(C)). In this example, a through-hole pattern with a diameter of 200 μm was used.

Next, development is performed using an organic solvent 6. At this time, the unexposed through-hole pattern portion 5 of the resist layer 3 is removed, leaving the exposed portion 4 (FIG. 1(d)). When the development is further progressed, a portion of the green sheet 2 is removed through the openings of the resist layer 3, that is, the through-hole pattern portions 5 (FIG. 1(e)). In this example, 1.1.1-trichloroethane (chlorocene) was used as the organic solvent 6.

Then, by removing the exposed portion 4 of the resist layer 3 that remains at the end, a green sheet 2 in which through holes 7 are formed can be obtained (FIG. 1(f)).

〔Effect of the invention〕

As explained above, in forming through-holes in a green sheet, the present invention does not use a mold, but includes the first step of forming a photosensitive resist layer on the surface of the green sheet, and the step of forming a photosensitive resist layer on the surface of the green sheet, The through-holes are formed through the second step of exposing to light, the third step of removing part of the green sheet together with the exposed resist, and the fourth step of removing the remaining resist layer, thus reducing costs. This also has the effect of shortening lead time.

[Brief explanation of drawings]

FIGS. 1(a) to 1f) are process explanatory diagrams showing one embodiment of the present invention, and FIGS. 2(a) to 2c) are process explanatory diagrams showing a conventional technique. DESCRIPTION OF SYMBOLS 1... Organic film, 2.15... Green sheet, 3... Resist layer, 4... Exposed part, 5... Through-hole pattern part, 6... Organic solvent (developer),
7.16...Through hole, 11...Upper mold, 12
...Pin, 13...Lower mold, 14...Hole.

Claims (2)

[Claims] 1. In a method for forming a through hole in a green sheet multilayer wiring board in which a plurality of green sheets are laminated and then fired all at once, a first step of forming a photosensitive resist layer on the surface of the green sheet, and a step of forming a through hole in the resist layer. The method is characterized by comprising a second step of exposing the hole pattern, a third step of removing a part of the green sheet together with the resist layer, and a fourth step of removing the remaining resist layer. Through-hole formation method. 2. 2. The through-hole forming method according to claim 1, wherein a dry film is used for the resist layer, the exposed portions of which are polymerized and remain after development.