JPS5824036B2 - How to form a via hole - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming via holes in a ceramic substrate on which electronic circuits are mounted.

Recently, ceramic substrates with good heat dissipation are being used to cope with the trend of high-density packaging of electronic circuits.
When forming via holes for electrically connecting patterns sandwiched between the substrates on this type of substrate, conventionally, the substrate is in a green sheet state before firing.
This was done by drilling holes in the sheet and then filling the holes with conductive paste.

This method not only takes time to process holes in the green sheet, but also has the drawbacks of low precision.
There has been a proposal to fill the green sheet 2 with the metal balls 1 via the ball placement jig 3, and to measure the conductivity between the patterns using the metal balls 1.

However, in this method, since the metal balls 1 are forcibly pushed into the green sheet 2, as shown in FIG. There are many cases where sheet waste 2a remains.

If the sheet waste 2a remains, it will cause poor conductivity between the upper and lower patterns, prevent the formation of good via holes, deteriorate production yields, and become a major hindrance to multilayer substrates. Therefore, some effective countermeasures are needed. It was wanted.

Therefore, the present invention uses a ball placement jig to arrange conductive metal balls at positions where via holes are to be formed in an insulating green sheet, and presses the arranged metal balls using a mold. This via is configured so that the metal balls are pressed into the green sheet and the sheet waste generated when filling the metal balls is suctioned by a suction means so that no sheet waste remains on the green sheet, thereby eliminating the above-mentioned drawbacks. The object of the present invention is to provide a method for forming holes.

Hereinafter, the present invention will be specifically explained based on an embodiment shown in the drawings.

As shown in FIG. 1, the metal ball filling device 5 has a mold 6, and as shown in FIG. recess 6a
are formed in large numbers.

Suction holes 6b are formed in each of the recesses 6a with one end open, and the suction holes 6b are joined together in the mold 6 and connected to an appropriate suction means such as a vacuum pump. ing.

As shown in FIG. 1, the receiver mold 6 has guide pins 6d,
6d' are provided upright, and a green sheet 2 having electrical insulation properties is placed between the guide pins 6d and 6d in the guide hole 2b.
, 2b, so that they can be freely inserted and engaged.

A ball placement jig 3 is provided on the green sheet 2 so that guide pins 6d and 6d can be freely inserted and engaged through guide holes 3a and 3a. The receiver is provided with a large number of cylindrical positioning holes 3b corresponding to the recesses 6a of the mold 6.

On the placement jig 3, as shown in FIG.
The push die 7 is provided with a number of convex portions 7b corresponding to the positioning holes 3b of the jig 3, and thus the recesses 6a of the receiver 6.

Since the metal ball filling device 5 has the above configuration, when forming a via hole in the green sheet 2, as shown in FIG. 2b, 2b are fitted and engaged with guide pins 6d, 6d, and the receiver is set on mold 6, and the ball placement jig 3 is similarly fitted with guide holes 3a, 3a into guide pin 6d.

6d and install it on the green sheet 2.

In this state, one conductive metal ball 1 such as gold is placed in each positioning hole 3b of the jig 3 as shown in FIG. , the guide holes 7a, 7a are engaged with the pins 6d, 6d, and are lowered in the figure.

Then, as shown in FIG. 2, the convex portion 7b of the pressing mold 7 comes into contact with the metal ball 1 in the positioning hole 3b, and by further moving the mold 7 downward in the figure, the ball 1 is positioned in the cylindrical shape. It is pushed into a predetermined via hole forming position on the green sheet 2 while being guided by the hole 3b.

At this time, as shown in FIG. 3, the green sheet surface 2c
In the recess 6a of the mold 6, excess sheet waste 2a is gradually pushed out by inserting the ball 1 into the sheet 2, but the recess 6a has a suction hole 6b connected to a suction means. Therefore, the sheet waste 2a is suctioned through the suction hole 6b and does not remain on the green sheet 2.

When the press die 7 and the ball placement jig 3 come into abutting engagement and the die 7 can no longer move downward in the figure, the metal balls 1 are moved to the green sheet 2 as shown in FIG. It is filled in a predetermined position inside.

Furthermore, the suction force of the suction means acting on the green sheet 2 through the suction hole 6b is not strong enough to suction the metal balls 1 in the green sheet 2 even if it suctions the sheet waste 2a, so the metal balls 1 is a predetermined position in the green sheet 2,
That is, a part of the ball 1 is on the surface 2c of the green sheet 2.
, 2 c' in an evenly exposed position.

In this state, as shown in FIG.
are formed and then laminated to form a multi-layered structure under pressure using a press.

Then, a pattern layer consisting of a large number of patterns 10 is formed between the stacked green sheets 2, and metal balls 1 are formed between adjacent pattern layers sandwiching the green sheets 2.
The predetermined patterns are electrically connected to each other.

At this time, since no sheet waste 2a remains on the green sheet 2, the metal balls 1 can reliably connect the predetermined patterns.

The multilayered green sheet 2 is fired at a high temperature in this way, and a ceramic multilayer circuit board is completed.

As explained above, according to the present invention, the sheet waste 2a pushed out when filling the metal balls 1 is suctioned using the suction means, so that the sheet waste 2a does not remain on the green sheet 2. This makes it possible to form good via holes, which not only improves the reliability of ceramic multilayer circuit boards, but also improves production yields and makes it possible to provide inexpensive multilayer circuit boards.

[Brief explanation of the drawing]

Figure 1 is a front view showing an example of a metal ball filling device, Figure 2 is a front view showing an example of a metal ball filling device;
5 through 5 are process diagrams showing one embodiment of the via hole forming method according to the present invention, FIG. 6 is a front view showing a conventional via hole forming method, and FIG. 7 is a process diagram showing an embodiment of the via hole forming method according to the present invention. FIG. 3 is a front cross-sectional view showing a manufactured green sheet. 1. ... Metal ball, 2 ... Green sheet, 2a ... Sheet scrap, 3 ... Ball placement jig, 6b ... Suction hole, 7...
Press type.

Claims (1)

[Claims] 1 Arrange conductive metal balls using a ball placement jig at the positions where via holes are to be formed in the insulating green sheet, and press the arranged metal balls into the green sheet using a press die. A method for forming a via hole in which sheet waste generated when filling with metal balls is suctioned by a suction means so that no sheet waste remains on the green sheet.