JPS58182293A - Thick film circuit board - 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 The present invention relates to a thick film wiring board having cross wiring.

The conventional method for manufacturing thick film wiring boards is as shown in Figure 1.
A woven fabric made of fibers such as nylon, tetron, or stainless steel wire is stretched over a wooden or metal frame, and the areas other than the printed areas on the woven fabric are coated with a photosensitive emulsion using a known optical pattern forming method. Plate 2 made by blocking 1.
A screen printing method is used in which printing ink 3f is placed and a spatula-shaped rubber plate 4 called a squeegee is pressed and slid on the woven fabric to push out the ink through the holes of the woven fabric and apply it onto the substrate 1. I was building a circuit.

With this printing method, the following problem arises when thick film wiring is formed on a substrate with convex portions or four-part stepped portions.

Specifically, as shown in FIGS. 2a and 2b, a first conductor 6 is screen printed on an insulating substrate 6 made of ceramic or the like, and then fired to form a first conductor 6 having a thickness of about 10 to 15 μm. A conductor is formed, and an insulator 7 is formed to a thickness of about 40 to 60 μm using the same method as described above. Here, the insulator 7 is connected to the first conductor 6 and the second conductor 8.
Since it is necessary to prevent short circuits and increase the withstand voltage, the thicker the insulator film is, the more advantageous it is.
It is said that the thickness must be more than μm. Therefore, when a convex portion is formed on the substrate and the second conductor 8 is printed on the insulator 7, the second conductor 8 is likely to be disconnected at the edge of the insulator 70 due to the step of the insulator 7. In other words, if the direction of movement of the squeegee is the direction of arrow 1, the front edge 7a of the insulator, that is, the edge where the squeegee falls from the insulator 7 to the insulating substrate 5, is where the squeegee jumps. It was easy to cause disconnection.

As a method for solving the above problem, cross wiring shown in FIGS. 3a and 3b has been proposed. This is the first layer on the insulating substrate 5.
Print the conductor 6 in the same manner as described above.

After firing, the insulator 7a is formed, and then the insulator 7b, which has a smaller area than the insulator 7a, is formed in a step-like manner, and by reducing the steps, the second conductor 8 can be printed without disconnection, which prevents disconnection. is an effective method. However, this method has problems such as printing the insulator twice, which increases the number of printings and reduces productivity, and also increases costs because an extra screen plate has to be manufactured. Ta.

An object of the present invention is to solve the above-mentioned problems and provide a thick film wiring board that is highly reliable, highly productive, and inexpensive.

That is, according to the present invention, the first conductor is provided on the insulating substrate;
By providing an insulator between the second conductors that intersect with this, and providing a notch at the peripheral edge of the insulator that intersects with the second conductor, reliability can be improved without having to print the insulator twice. It is possible to form a second conductor with high conductivity.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 4a, b and 5a, b.
, will be explained with reference to FIGS. 6a, b, and c.

First, as shown in FIG. 4a, a first conductor 6 is printed and fired on an insulating substrate, and an insulator 7 having a notch 9 thereon is printed and fired.
form. Next, the second conductor 8 is printed as shown in FIG. At this time, when the squeegee 4 passes through the notch 9 of the insulator 7 as shown in FIG. In order to slide on the ink pushed out during printing, a second conductor 8 with no disconnection is connected as shown in Figure 6.
can be formed. Next, an example of the present invention was prepared using a stainless steel 325 mesh, a screen plate with an emulsion thickness of 16 μm, and a squeegee with a printing pressure of 3 and a squeegee speed of 13e.
m/sea, and after drying at 140°C for 10 minutes, the peak temperature was 850°C in a firing oven.

Baked for 10 minutes, film thickness 12 μm, 200-40 μm in conductor
A first conductor having a thickness of 0 μm was formed. Next, insulating paste (Typon 94291 stainless steel 200 mesh, emulsion thickness 30 μm, squeegee printing pressure 3Kp1, squeegee speed 13c1n/8eC squeegee, hardness 60 degrees) was printed,
After drying at 140℃ for 10 minutes, the peak temperature was 85℃ in a firing oven.
Baked at 0°C for 10 minutes, film thickness 40-80 μm, insulator size 2IIIp-41111', notch size 0.2
an to 0.511110, and an insulator was formed on the first conductor.

Next, the second conductor was made of stainless steel G325 mesh emulsion thickness 15 using Aq-pd paste in the same way as the first conductor.
Printing was performed using a μ screen plate at a squeegee printing pressure of 69, a squeegee speed of yes/sec, and a squeegee hardness of 60 degrees. In this case, the higher the squeegee printing pressure and the slower the speed, the better the result.

In the examples, the shape of the notch is rectangular, but the present invention is not limited to this. (The shape of the notch may be semicircular or triangular. A notch may be provided.As a specific example, Fig. 6 a, b,
Examples include the shape of the insulator shown in c. in short,
When printing the second conductor, the squeegee leaves the insulator after the second conductor ink continues on the second conductor on the insulator and is pushed out through the printing screen and contacts the insulating substrate. You should do it so that

As described above, according to the present invention, it is possible to obtain a second conductor without disconnection, and even if there is a step difference of 40 μm or more from the substrate surface, there is no printing defect, and the crossed thick film wiring board is highly reliable, highly productive, and inexpensive. can be obtained.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an apparatus showing a conventional screen printing method;
Figures 2a and b are a plan view and a sectional view of a conventional thick film wiring board, Figures 3a and b are a plan view and a sectional view of another conventional thick film wiring board, and Figures 4a and b are a bookmark. FIGS. 5a and 5b are a plan view in which an insulator is formed on the first conductor and a plan view in which a second conductor is formed in the insulator in a thick film wiring board according to an embodiment of the invention. , cross-sectional views of the thick film wiring board during and after printing the second conductor, FIG. b and a are plan views of a thick film wiring board according to another embodiment of the present invention. 6...--Insulating substrate, 6... First conductor, 7
・-・・・・・・Insulator, 8... Second conductor,
9...Notch part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 IJ4 @ Figure 5 (α) Figure 6 (α, y

Claims (1)

[Claims] A thick film wiring board in which a first conductor is formed on an insulating substrate, an insulator is formed inverted on the first conductor, and a second conductor is further sequentially formed on the insulator. A thick film wiring board in which a first conductor and a second conductor are provided to intersect with each other, and a notch is provided at a peripheral edge of the insulator that intersects with the second conductor.