JPS60245296A - Method of forming through hole by thick film printing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming through holes by thick film printing in multilayer film circuits used in hybrid integrated circuits and the like.

In recent years, hybrid integrated circuits have been widely used in electronic devices, which have advantages such as smaller size, higher reliability due to fewer connection points, and the ability to incorporate various active and passive elements.
There is.

Compared to thin film circuits, thick film circuits, which are a type of thick film circuit that is the basis of the configuration of hybrid integrated circuits, are relatively easy to create screens, and the manufacturing equipment is inexpensive. Furthermore, there are advantages such as the ability to connect multilayer film conductors using through-hole means.

However, on the other hand, in the through-hole connecting the lower film conductor and the upper film conductor formed with the insulating layer in between, the through-hole conductor filled in the through-hole or the F part film conductor and the lower film conductor have a resistance. A connection with low loss and high reliability is required. [Prior Art] A conventional method for forming through holes by thick film printing will be described with reference to side cross-sectional views of the process sequence shown in FIG.

(a) Formation of lower film conductor (see Figure 2(a))
For example, a pattern of a heg-Pd based lower film conductor 2 is printed on the surface of an alumina substrate (1) using a desired screen, and then baked.

(b) Formation of first thickness jii insulating layer - see FIG. 2(b) Except for through-hole holes 4 provided at desired through-hole locations on the lower film conductor 2, the upper surface of the lower film conductor 2 is included. A first N film insulating layer 3 is screen printed on the entire surface of the insulating substrate 1 and fired.

This thick film insulating layer is, for example, a thick film dielectric layer of glass-filled paste.

(c) Formation of hole-filling conductor - See Figure 2 (C) Screen printing so that the through-hole hole 4 of the first thick film insulating layer 3 is filled with a conductive paste made of the same material as the upper film conductor 2. Then, the hole-filling conductor 5 is fired. - (d) Formation of a second thick film insulating layer - see FIG. 2(d) Overlapping the surface of the first thick film insulating layer 3, provide holes 7 for through holes at locations corresponding to the hole-filling conductors 5. The second thick film insulation layer 6 is screen printed and fired.

(e) Formation of upper film conductor - see FIG. 2(e) Using a desired second screen on the surface of the second thick film insulating layer 6,
For example, a pattern of the upper film conductor 8 of Ag--Pd system is printed and fired.

At the same time as this printing process, the through-hole hole 7 is filled with a hole-filling conductor 8a, which is connected to the head of the hole-filling conductor 5 to connect the lower membrane conductor 2 and the upper YB membrane conductor 8. The hall is completed.

As described above, since the first thick film insulating layer 3 and the second thick film insulating layer 6 are laminated, even if a pinhole occurs in either of the thick film insulating layers, the first thick film insulating layer 3 and the second thick film insulating layer 6 are stacked. The probability that pinholes occur at the same location in the two-thickness insulating layer 6 is extremely rare. Therefore, the lower film conductor 2 and the upper film conductor 8 can be reliably insulated except for the through holes.

[Problem that the invention seeks to solve]

However, in the above conventional through hole forming method, since the surface of the lower film conductor 2 is flat, when printing the first thick film insulation N3, the insulating paste is applied to the lower part of the through hole hole 4 as shown in FIG. There is a risk that the particles may flow in and become buried as shown by symbol M shown in b).

Therefore, the connection resistance of the through hole increases. Furthermore, in the worst case, there is a problem that the connection between the partial membrane conductor 2 and the upper membrane conductor 8 is broken.

On the other hand, when printing the hole-filling conductor 5, the head of the hole-filling conductor 5 protruding from the surface of the first thick film insulating layer 3 is crushed as indicated by the symbol N shown in FIG. There is a possibility that the liquid may flow to the surface of the membrane insulating layer 3.

When through holes are placed close together,
If this happens, a problem arises in that adjacent conductor patterns are short-circuited.

[Means for solving problems]

The problems with the conventional method include the step of printing and forming a lower film conductor on the surface of an insulating substrate, followed by the step of printing and forming a protruding through-hole conductor on the bottom film conductor, and the step of printing and forming a through-hole conductor on the surface of the insulating substrate, and the process of printing the through-hole conductor except for the through-hole conductor. The substrate includes a step of printing and forming a first thick film insulating layer, and a second thick film insulating layer having through holes formed above the through hole conductors on the entire surface of the first thick film insulating layer. Step 1: Printing and forming, on the surface of the second thick insulation layer,
Solved by the through-ball forming method of the present invention, which includes printing the hole-filling conductor and the upper film conductor.

[Effect]

According to the present invention, since the through-hole conductor is provided prior to the formation of the first W gland insulating layer, the lower part of the through-hole is not blocked by the insulating paste. Furthermore, when printing holes for through holes in the second thick insulating layer, the heads of the through hole conductors protrude above the surface of the first thick insulating layer formed previously, so the insulating paste is applied to these through holes. Do not flow into the head of the conductor.

Furthermore, even if the head of the through-hole conductor collapses when printing the through-hole conductor, it will only be formed into a conical shape on the upper membrane conductor and will not short-circuit with the adjacent conductor pattern.

In this way, a through hole is formed that connects the lower film conductor and the upper film conductor, with low resistance loss and high reliability.

〔Example〕

The gist of the present invention will be specifically explained below with reference to the embodiment shown in FIG. Note that the same reference numerals indicate the same objects throughout the plan.

FIG. 1 is a side sectional view showing the method for forming through holes by thick film printing according to the present invention in the order of steps.

(a) Formation of lower film conductor - See Figure 1(a) Insulating substrate (
For example, on the surface of an alumina substrate (1), using a desired screen, a pattern of a lower film conductor 2 made of, for example, Ag--Pd and having a desired width and thickness of, for example, about 15 μm is printed and fired.

(b) Formation of a through-ball conductor - See Figure 1(b) A through-hole conductor 15 made of the same material as the lower membrane conductor 2 is projected and screen-printed at a desired through-hole location on the lower membrane conductor 2, and then fired. . The diameter of the through-hole conductor 15 is, for example, about 0.3 mm, which is smaller than the width of the conductor 2 in part.

(c) Formation of first thick film insulating layer - See FIG. 1(C) A first thick film insulating layer 13 is formed on the entire surface of the insulating base &1 including the lower film conductor 2, excluding the top of the through hole conductor 15. Screen print and fire. Note that this thick film insulating layer is, for example, a thick film dielectric layer made of glass-containing paste, and the thickness above the lower film conductor 2 is, for example, about 20 μm.

(d) Formation of a second thick insulating layer - see FIG. 1(d) Overlapping the surface of the first thick insulating layer 13, holes 17 for through holes are formed at locations corresponding to the through hole conductors 15. The second thick film insulation [16] is screen printed and fired.

(E) Formation of the lower film conductor 8 Using a desired second screen on the surface of the second thick film insulating layer 16 (see FIG. Print the pattern and fire it.

Incidentally, at the same time as this printing process, the through-hole holes 17 are filled with a conductive paste to form hole-filling conductors 8a. Therefore, the hole-filling conductor 8a is the through-hole conductor 15.
A through hole connecting the lower membrane conductor 2 and the partial membrane conductor 8 is completed.

As described above, in the present invention, the through-hole conductor 15
Since it is provided prior to the formation of the thick film insulating layer 13, the lower part of the through hole is not blocked by the insulating paste. Furthermore, when printing the through-hole holes 17 of the second thick insulation layer 16, the first thick insulation layer 16 that has been previously formed.

Since the head of the through-hole conductor 15 protrudes above the surface of the insulating layer 13, the insulating paste does not flow into the head of the through-hole conductor 15.

Furthermore, even if the head of the through-hole conductor 15 collapses during printing, it will only be formed in a conical shape on the lower film conductor 2 and will not short-circuit with adjacent conductor patterns.

Although the illustrated example has two layers of film conductors, the present invention is not limited to 2N film conductors, and can be implemented to multilayer film conductors of 3N or more.

〔Effect of the invention〕

As explained above, according to the present invention, the through holes that connect the film conductors formed in multiple layers to the insulating substrate have significant practical effects, such as low resistance loss and high reliability.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of one embodiment of the present invention, not showing the process order, in which (a) is a step of forming a lower film conductor, (b) is a step of forming a through-hole conductor, and (c) is a step of forming a first thick film conductor. (d) is the formation process of the second thick insulating layer; (e) is the formation process of the upper film conductor; FIG. In the cross-sectional views, (a) shows the process of forming the lower film conductor, (b) shows the process of forming the first thick insulating layer, (C) shows the process of forming the hole filling conductor, and (d) shows the process of forming the second thick insulating layer. Formation step (e) does not show the formation step of the upper film conductor. In the figure, 1 is an insulating substrate, 2 is a lower film conductor, 3.13 is a first thick film insulating layer, 4.7.17 is a hole for a through pole, 5.88 is a hole filling conductor, 6 and I6 are a second film conductor. A thick film insulating layer, 8 a cross-section conductor, and 15 a through-hole conductor are shown, respectively. Agent: Patent Attorney Hiroshi Matsuoka

Claims (1)

[Claims] Following the step of printing and forming a lower film conductor on the surface of the insulating substrate, the step of printing and forming a protruding through-hole conductor on the lower film conductor, and the step of printing a first thick film on the entire surface of the insulating substrate except for the through-hole conductor. a step of printing an insulating layer; a step of printing a second thick film insulating layer having through holes formed above the through hole conductors on the entire surface of the first thick film insulating layer; A method for forming through holes by thick film printing, the method comprising the step of printing a hole-filling conductor and a lower film conductor on the surface of an insulating layer.