JPS6020888B2 - thick film integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thick-film integrated circuit, and more particularly to a thick-film integrated circuit including a thick-walled capacitor in which a dam for preventing drooping of an upper electrode lead-out portion is formed continuously on a compact body layer. be.

Thick film capacitors are formed by sequentially printing and firing a lower electrode, dielectric layer, and upper electrode on a ceramic substrate, but in this case, care must be taken to prevent printing from sagging around the lead-out part from the upper electrode. Therefore, it is necessary to provide a continuous dam in the dielectric layer, and if the dielectric is a high dielectric material mainly made of barium titanate, which has poor bubble resistance, crystalline glass is used to cover the dielectric layer. It is necessary to completely cover the glass with a moisture-resistant coating layer such as an undercoat with amorphous glass and an overcoat with an amorphous glass to improve moisture resistance.

FIGS. 1a and 1b show an example of an integrated circuit of a conventional thick film capacitor and a thick resistor 12 having the configuration as described above.

In FIG. 1, reference numeral 1 denotes a ceramic substrate, on which two lower electrodes 2, 2 and a wiring electrode are formed, and on one of the lower electrodes 2, a low dielectric layer 3 and an upper electrode 5 are formed.
are formed sequentially. Note that 9 is a dam made of a low dielectric material and integrally formed with the low dielectric layer 3 in order to prevent printing sag 7 from the lead-out portion 6 of the upper electrode 5. A high dielectric layer 4 and an upper electrode 5 thereon are formed on the other lower electrode 2, and a printed drip from the lead-out portion 6 of the upper electrode 5 is formed continuously on the high dielectric layer 4. A dam 8 made of a high-voltage material is formed to prevent this.

In this case, unlike the low dielectric material, the high dielectric material is made of a material with poor moisture resistance (such as barium titanate), so the high dielectric material layer 4 is coated with an undercoat 10 and an overcoat 11 that are anti-green. It is necessary to cover with a coating layer,
Conventionally, as described above, the dam 8 was formed of the same material as the high-conductivity layer 4, so the portion including the dam 8 had to be completely covered with the moisture-resistant coating layer. For this reason, the proportion of thick film capacitors in the thick film integrated circuit Sakagami 5 has become large.

SUMMARY OF THE INVENTION It is an object of the present invention to alleviate the above-mentioned problems and to reduce the proportion of thick film capacitors on a thick film integrated circuit board.

In order to achieve the above object, the present invention replaces the dam for preventing drooping of the lead-out portion from the upper electrode in a dielectric thick film capacitor with poor moisture resistance by using an insulator with better moisture resistance than the dielectric constituting the capacitor. It is characterized by eliminating the need to completely cover the dam portion with a moisture-resistant coating layer, thereby reducing the proportion of thick film capacitors on the circuit slope.

An embodiment of the present invention will be described below with reference to FIG.

The embodiment shown in FIG. 2 is similar to the embodiment shown in FIG.
This is a thick film integrated circuit in which a low dielectric thick film capacitor, a high dielectric thick film capacitor, and a thick film resistor 12 are formed on a substrate 1, and the configuration other than the high dielectric thick film capacitor is shown in FIG. , so the same parts are given the same reference numerals and the explanation thereof will be omitted.

In the present invention, the dam 13 for preventing drooping of the lead-out portion from the upper electrode is not formed of the same material as the high concession body layer 4 as in the past, but is made of a material having better rope resistance than the commercial power body layer 4. A moisture-resistant coating layer formed of an insulator and covering the commercial electrical body layer 4 is disposed so as to completely cover at least the commercial electrical body layer 4.

That is, the moisture-resistant coating layer does not completely cover the dam 13. Note that the dam 13 is a low dielectric material 3.
It may be the same as the undercoat 10, and crystalline glass made of the same material as the undercoat 10 may also be used. In this way, the present invention provides the dam 13 of the dielectric thick film capacitor with poor overflow resistance.
Since the capacitor is made of an insulator that has better green resistance than the dielectric material that makes up the capacitor, it is no longer necessary to completely cover the dam 13 with the undercoat 10 and overcoat 11 as in the conventional case. It is possible to reduce the proportion of the thick capacitor on the circuit board by making the thick capacitor into a 4-type type.

As explained above, in the present invention, a dam is formed around the lead-out portion of the upper electrode of a thick film capacitor, which is more resistant to greenery than the dielectric material that makes up the capacitor. It is no longer necessary to completely cover the dam with an undercoat and an overcoat for making the housing moisture resistant, and the proportion of thick film capacitors on the integrated circuit board can be reduced accordingly.

[Brief explanation of the drawing]

1A and 1B are a plan view and a sectional view taken along the line A-A of the thick film capacitor in a related thick film integrated circuit, and FIG. 2 is a plan view of an example of the thick film integrated circuit according to the present invention. be. 1... Ceramic substrate, 2... Lower electrode, 3...
Low dielectric layer, 4... High dielectric layer, 5... Upper electrode,
6... Upper electrode extraction part, 7... Printing sag, 8, 9
...Dam made of the same material as the concession layer, 10...
Undercoat, 11... Overcoat, 13...
- A dam made of a material with better moisture resistance than the exposed body layer. Figure 2 Figure 1

Claims (1)

[Claims] 1 A substrate, a lower electrode formed on the substrate, a dielectric layer with poor moisture resistance such as a high dielectric constant material formed on the lower electrode, an upper electrode formed on the dielectric layer, and the In a thick film integrated circuit including a thick film capacitor comprising a lead-out part, a dam for preventing drooping of the lead-out part provided around the upper electrode lead-out part, and a moisture-resistant coating layer covering the dielectric layer, the upper part The dam for preventing drooping of the electrode lead-out portion is formed of an insulator having better moisture resistance than the dielectric material constituting the capacitor, and the moisture-resistant coating layer is arranged to completely cover at least the dielectric layer. A thick film integrated circuit characterized by: