JPS588587B2 - Method for manufacturing thick film integrated circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a thick film resistor for a thick film integrated circuit device.

In normal thick film integrated circuit devices, capacitors and active elements are attached as external components, so the only things made of thick film are thick film resistors and thick film wiring.

A typical example of this thick film is cermet, which is created by screen printing a paste of silver, platinum, palladium, etc. and then sintering it.

Below, each production step of the conventional method for producing a thick film resistor is explained.
This will be explained with reference to FIGS.

FIG. 1a is a plan view showing the first production stage, and FIG. 1b is a cross-sectional view taken along line 2B--2B in FIG. 1a.

As shown in FIGS. 1a and 1b, a cermet thick film 2 having a predetermined pattern is formed on a substrate 1 made of an insulating material such as alumina porcelain, and a portion thereof is used as a thick film resistor 3. As shown in FIGS.

FIG. 2a is a plan view showing the second production stage, and FIG. 2b is a sectional view taken along the line 2B--2B in FIG. 2a.

As shown in FIGS. 2a and 2b, a rectangular glass coating 4 is prepared to cover the thick film resistor 3 in order to protect the thick film resistor 3 from moisture and impurities and to stabilize its resistance value.

This glass coating 4 is created by screen printing glass powder made into a paste and then sintering it.

FIG. 3a is a plan view showing the third production stage, and FIG. 3b is a sectional view taken along the line 2B--2B in FIG. 3a.

As shown in FIGS. 3a and 3b, a solder layer 5 is deposited on the cermet thick film 2 other than the thick film resistor 3, and thick film wiring 6 is created to connect to both ends of the thick film resistor 3. do.

By the way, when the thick film resistor 3 created in this way is used for a long time under conditions where the temperature is repeatedly high, the temperature of the thick film resistor 3 becomes even higher due to heating due to the resistance loss. Thermal stress due to the difference in thermal expansion coefficients acts repeatedly on the interface between the glass coating 4 covering the thick film resistor 3 and the solder layer 5.

For this purpose, the thick film resistor 3 and the solder layer 5 at the interface
A tear occurs between the cermet thick film 2 which is the underlayment, and this tear not only causes a significant change in the connection resistance between the thick film resistor 3 and the thick film wiring 6, but also causes a There was a drawback that there was a risk of wire breakage occurring between the two.

Furthermore, if the glass coating 4 is kept at a high temperature for a long time, the solder layer 5 will melt the glass coating 4, so that the solder layer 5 will melt on the glass coating 4, as shown by the broken line A in FIG. 3b. It starts to flow into.

Therefore, the thermal stress generated between the glass coating 4 and the solder layer 5 that has flowed thereon causes cracks in the glass coating 4, which may hinder the stabilization of the thick film resistor 3. There were also drawbacks.

All of these drawbacks are exacerbated as the thickness of the solder layer 5 increases at the interface between the glass coating 4 and the solder layer 5.

This invention was made in view of the above-mentioned drawbacks, and by forming a glass coating on a conductive thick film and having an uneven shape at both side edges, the solder layer in contact with the both side edges of the glass coating is formed. The thickness is reduced to reduce the thermal stress generated at the interface between the solder layer and the glass coating, and to suppress the solder layer from flowing onto the glass coating, making it possible to avoid conditions where the temperature is repeatedly high. The purpose of the present invention is to provide a thick film resistor that can withstand long-term use.

Hereinafter, each manufacturing step of an embodiment of the method for manufacturing a thick film resistor according to the present invention will be explained with reference to FIGS. 4 to 6.

FIG. 4a is a plan view showing the first production stage, and FIG. 4b is a sectional view taken along the line 2B--2B in FIG. 4a.

The first production stage shown in FIG. 4 is exactly the same as the first production stage of the conventional example shown in FIG. 1, so the explanation will be omitted here.

FIG. 5a is a plan view showing the second production stage, and FIG. 5b is a sectional view taken along the line 2B--2B in FIG. 5a.

As shown in FIGS. 5a and 5b, a glass coating 4a is prepared on the cermet thick film 2, which is coated with the thick cermet film 2 and has an uneven shape at both end portions in contact with the thick cermet film 2.

FIG. 6a is a plan view showing the third production stage, and FIG. 6b is a sectional view taken along line Vl 137 VI B in FIG. 6a.

As shown in FIGS. 6a and 6b, a solder layer 5 is created on the cermet thick film 2 other than the thick film resistor 3 directly under the glass coating 4a, and a solder layer 5 is formed on the cermet thick film 2 to connect to both ends of the thick film resistor 3. A membrane wiring 6 is created.

At this time, the solder forming the solder layer 5 cannot easily flow into the recesses at both ends of the glass coating 4a due to its surface tension, and the solder flows along the cermet thick film 2 with slightly better solder flow. It simply flows into the recess.

Therefore, since the thickness of the solder layer 5 within the recessed portion is extremely thin, the aforementioned thermal stress occurring at the interface between the solder layer 5 and the glass coating 4a can be reduced.

Therefore, the occurrence of a tear between the thick film resistor 3 and the cermet thick film 2 can be suppressed due to this reduction in thermal stress.

Furthermore, by reducing the thickness of the solder layer 5 within the recessed portion, it is possible to suppress the solder layer 5 from flowing onto the glass coating 4a.

Although the description has been made so far regarding a cermet thick film, the method according to the present invention is not limited to this, and can be applied to other conductive thick films as well.

As described in detail above, in the method for producing a thick film resistor according to the present invention, a conductive thick film is created on a substrate made of an insulating material, and the conductive thick film is coated with the conductive thick film to cover both ends. A glass film having an uneven shape is created, and a solder layer is created on the remaining conductive thick film except directly under the glass film, resulting in the following effects.

That is, the surface tension of the solder in the solder layer allows the thickness of the solder layer within the recesses at both ends of the glass coating to be thinned, so that the thickness of the solder layer created by the conductive thick film directly under the glass coating can be reduced. Even if a thick film resistor is used for a long time under conditions of repeated high temperatures, it is possible to reduce the thermal stress generated at the interface between the solder layer and the glass coating, and also to reduce the thermal stress generated at the interface between the solder layer and the glass coating. Flowing onto the glass coating can be suppressed.

Therefore, due to the reduction in thermal stress, cracks are prevented from occurring in the conductive thick film, and variations in connection resistance and disconnection between the thick film resistor and the thick film wiring connected thereto are prevented. In addition, by suppressing the flow of the solder layer onto the glass coating, the generation of cracks in the glass coating can be prevented, and the stabilization of the thick film resistor due to the cracks can be prevented. It can be prevented.

[Brief explanation of the drawing]

Figure 1a is a plan view showing the first manufacturing step of the conventional thick film resistor manufacturing method, Figure 1b is a sectional view taken along the line ■B-■B in Figure 1a, and Figure 2a is is a plan view showing the second production stage of the above conventional production method, FIG. 2b is a sectional view taken along the line ■B-■B of FIG. A plan view showing the production stage of 3, Fig. 3b is the same as ■B-■B in Fig. 3a.
4a is a plan view showing the first manufacturing step of an embodiment of the method for manufacturing a thick film resistor according to the present invention, and FIG. Cross-sectional view along line B, Figure 5a
is a plan view showing the second production stage of the above embodiment, FIG. 5b
is a sectional view taken along the line ■B--■B in FIG. 5a, FIG. 6a is a plan view showing the third production stage of the above embodiment, and FIG.
It is a sectional view taken along the line ■B-■B in Figure a. In the figure, 1 is a substrate, 2 is a cermet thick film, 3 is a thick film resistor, 4 and 4a are glass coatings, 5 is a solder layer, and 6 is a thick film wiring. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. The first step is to create a conductive thick film on a substrate made of an insulating material, and the second step is to form a glass film that covers this conductive thick film and has uneven edges on both sides in contact with the conductive thick film.
and a third step of forming a solder layer on the conductive thick film excluding the portion immediately below the glass coating.