JP2623748B2 - Thick film circuit device - Google Patents

Description

The present invention relates to a thick film circuit device such as a hybrid IC.

(B) Conventional technology FIG. 3 (A) is a plan view of a main part showing a conventional thick film circuit device, and FIG. 3 (B) is a sectional view.

In the thick film circuit device, as shown in FIG. 3 (A), opposing lower conductor patterns 72, 72 are formed on the upper surface of the substrate 71 by printing, respectively, An insulating cloth 73 is formed by printing in a shape, and an upper layer conductor pattern 74 is formed by printing on the insulating cloth 73. Both ends of the upper conductor pattern 74 are connected to a lower conductor 75 formed on the substrate 71. Further, a resistor 76 for connecting between the upper conductors 72a, 72a is formed by printing on the tip side of each lower conductor pattern 72, that is, on the tip side of the two upper conductors 72a, 72a constituting each upper conductor pattern 72. ing.

(C) Problems to be Solved by the Invention Generally, in a thick film circuit device, a resistor (printing resistor)
Is represented by R = ρ · L / W. L is the length, W is the width, and ρ is the sheet resistance. That is, ρ is determined in a manufacturing process in which the dry film thickness at the time of printing is constant, and L and W are determined as a relational expression between the aspect ratio (L / W) and R in a constant manufacturing process after printing for each dimension. You.
Therefore, in order to obtain a resistance value as designed, it is necessary that the printed film thickness and shape dimensions are printed correctly. Usually, the average film thickness of the upper conductor pattern and the lower conductor pattern after firing is about 12 μm, and the thickness of the insulating cloth is about 25 μm.
The printed thickness of the resistor is about 25 μm.

By the way, as shown in FIG. 3A, due to the layout of the circuit pattern, an insulating cloth (upper conductor pattern) is required.
74 (which separates the lower conductor pattern 72 from the lower conductor pattern 72) may be arranged near the resistor 76. In this case, the resistor 76 is located in a valley surrounded by the insulating cloths 73, 73, and the resistor printed surface is at a position extremely lower than the printing squeegee surface. That is, the height h from the printing board surface to the printing press squeegee surface is about 49 μ. In resistance printing,
The resistance paste dropped by the squeegee from the opening of the silk screen is formed from the sum of the height h and the emulsion film thickness of the silk screen (see FIG. 3 (B)). Therefore, in the conventional resistance printing, the distance is too large, so that the resistance paste does not correctly adhere to the substrate surface. Alternatively, there is a disadvantage that the film thickness and shape dimensions do not become as designed even if they adhere. Of course, the resistor of the thick film circuit is usually adjusted to the target resistance value by a trimming operation, but if the initial resistance value exceeds the allowable value or is lower than the lower limit of the trimming as described above, There is a disadvantage in that trimming is inferior, resulting in lower product yield, lower performance, higher product cost, and the like. Also, by arranging the insulation cloth as far as possible from the resistor,
It is conceivable to eliminate disadvantages caused by insulating cloth,
In this case, there is a disadvantage that the degree of freedom in circuit pattern design is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thick film circuit device that can obtain a free circuit pattern and obtain a correct resistance value as designed.

(D) Means and action for solving the problem In order to achieve this object, the thick film circuit device of the present invention has the following configuration.

The thick-film circuit device forms a plurality of lower-layer conductor patterns on an upper surface of a substrate, forms an insulating cloth having a constant width, length, and thickness on the lower-layer conductor patterns, and forms at least two upper-layer conductors on the insulating cloth. Is formed, and a resistor is connected and formed between the two upper conductors.

In the thick-film circuit device having such a configuration, for example, two lower-layer conductor patterns are printed in parallel at predetermined intervals on a substrate, and an insulating cloth having a constant width, length, and thickness is formed. It is formed by printing over the upper surfaces of both lower conductor patterns. An upper conductor pattern including at least two upper conductors is printed on the insulating cloth. Further, a resistor is formed by printing between the two upper layer conductors. Therefore, when printing the resistor, only the upper layer conductor (12 μm + screen emulsion thickness) having a thickness of 12 μm on the insulating cloth surface may be considered. That is, in the resistance printing, the insulating cloth surface is equivalent to the printed board surface, and the distance between the resistance printing surface (insulating cloth surface) and the silk screen surface is extremely short. This allows
The resistive paste transmitted by the squeegee through the opening of the silk screen can be printed and formed between the upper conductors with the designed dimensions (width, length) and thickness as designed. Therefore,
The resistance value of the resistor can maintain a trimmable range,
Not only can the product yield and the performance be improved, but also the degree of freedom in circuit pattern design can be ensured.

(E) Embodiment FIG. 1 is a plan view of a principal part showing a specific embodiment of a thick film circuit device according to the present invention, and FIG. 2 is a side view of a principal part.

The thick-film circuit device has two
The two lower conductor patterns 2 and 2 are printed and formed in parallel, and a fixed width, length and
A rectangular insulating cloth 3 having a thickness is printed and formed orthogonally. That is, the insulating cloth 3 is formed by printing over the two lower-layer conductor patterns 2 and 2. And
An upper conductor pattern 4 is printed on the insulating cloth 3. This upper conductor pattern 4 is composed of two upper conductors 4
1 and 41. In the embodiment, the two upper-layer conductor patterns 4, 4 are arranged to face each other from both ends of the insulating cloth 3 to the center. The base end of each upper conductor pattern (upper conductor 41) 4, that is, the end of the insulating cloth 3 is connected to the lower conductor 5 formed on the substrate 1. Also, a resistor (resistance element) 6 for connecting the upper layer conductors 41, 41 is provided at the tip of the upper layer conductors 41, 41 of each upper layer conductor pattern 4.
Is printed. In printing the resistor 6, a silk screen is used (not shown) as in the prior art, and the resistor paste is transmitted through a resistor paste through an opening of the screen with a squeegee and printed and fired.

In the thick film circuit device having such a configuration, the insulating cloth 3 is formed on the upper surface of the lower conductor pattern 2 on the substrate 1,
An upper conductor pattern 4 is formed on the insulating cloth 3. Therefore, in the resistor 6 connected between the upper conductors 41, 41 of the upper conductor pattern 4, the surface of the insulating cloth 3 becomes equivalent to the surface of the printed board at the time of printing. This allows
As shown in the cross-sectional view of FIG. 2, it is only necessary to consider the thickness (12 μ) of the upper conductor 41 on the insulating cloth 3 and the thickness of the screen emulsion when forming the low antibody 6 print. That is, the distance between the insulating cloth 3 surface and the silk screen surface is extremely small (see “h” shown in FIG. 2). Accordingly, the thick insulating cloth 3 (having a height higher than the surface of the substrate 1) located in the vicinity of the resistive printing surface does not interfere with the conventional method, and the resistive paste has the designed shape and dimensions (width and length). ), It can be formed to a thickness

Thus, the resistance value can be formed in a range that can be trimmed, the yield of the product is improved, and as a result, the performance can be improved and the cost can be reduced.

The printing of the insulating cloth 3 under the printing resistor 6 is usually performed by 2
Although the number of times, the number of times of printing is increased and the thickness of the insulating cloth 3 is adjusted in relation to other squeegee printing surfaces, so that a print resistor 6 with higher reproducibility can be realized.

(F) Effects of the Invention In the present invention, as described above, an insulating cloth having a fixed width, length, and thickness is formed on a lower conductive pattern formed on the upper surface of a substrate, and an upper conductive pattern is formed on the insulating cloth. When the resistor is formed between the upper conductors forming the upper conductor pattern, the insulating cloth surface is equivalent to the printed board surface during resistance printing. Therefore,
The distance between the insulating cloth surface and the silk screen surface is extremely small, and a resistor having the designed length, width and thickness can be obtained. As a result, the resistor printed surface and the insulating cloth are located close to each other as in the related art, so that the resistance value of the resistor is not as designed, trimming is impossible, and product yield deterioration is not allowed. It has excellent effects of achieving the object of the invention, such as securing the freedom of pattern design and improving the performance.

[Brief description of the drawings]

FIG. 1 is a plan view of an essential part showing a thick film circuit device according to an embodiment, and FIG.
FIG. 1 is a side view of a main part showing a thick film circuit device according to an embodiment. FIG. 3 (A) is a plan view of a main part showing a conventional thick film circuit device.
FIG. 1B is a sectional view of a main part showing a conventional thick film circuit device. 1: substrate, 2: lower conductor pattern, 3: insulating cloth, 4: upper conductor pattern, 6: resistor.

Claims (1)

(57) [Claims] A plurality of lower conductor patterns are formed on an upper surface of a substrate, and an insulating cloth having a constant width, length, and thickness is formed on the lower conductor pattern. At least two upper conductors are formed on the insulating cloth. Forming an upper conductor pattern,
A thick film circuit device comprising a resistor connected between the two upper conductors.