JPH0834341B2 - Method of manufacturing circuit board with thick film resistor - Google Patents

Description

The present invention relates to a method of manufacturing a circuit board with a thick film resistor used as, for example, a hybrid IC or the like.

[Prior Art] This type of thick film resistor-equipped circuit board is generally
For example, as shown in FIG. 2, a paste-like conductor 4 containing Ag-Pd or Cu as a main component is printed on the surface of a fired alumina substrate 2 and then fired, and then RuO ₂ system or La is used.
The cermet resistor ₆ such as B6 series was printed and fired.

[Problems to be Solved by the Invention]

However, the conductor 4 previously formed on the alumina substrate 2 usually has a film thickness of about 10 to 15 μm, and since this thickness becomes a step, the size of the resistor 6 becomes small (for example, 0.5 mm).
□) or less), the printability of the resistor 6 formed by screen printing on the conductor 4 (that is, whether or not the resistor 6 is printed accurately) becomes a major obstacle. There is.

Therefore, it is a primary object of the present invention to provide a method of manufacturing a circuit board with a thick film resistor, which enables the resistor to be formed with good printability even when the resistor is small.

[Means for solving the problem]

In order to achieve the above object, the manufacturing method of the present invention comprises the steps of preparing a flat ceramic green sheet and printing a conductor on the surface thereof, and pressing the product obtained in this step to maintain the flat shape. Up to the step of smoothing the printed surface of the conductor, the step of simultaneously firing the ceramic green sheet and the conductor of the one obtained in this step, and the surface of the one obtained in this step, so that the cermet resistance It is characterized by comprising a step of printing a body and a step of subsequently firing the cermet resistor.

[Action]

According to the above-mentioned manufacturing method, since the conductor printing surface is smoothed and then the resistor is printed on the surface, there is no step due to the conductor as in the conventional example. Therefore, even if the resistor is small, its printability is conventionally It is much better than the example.

〔Example〕

FIG. 1 is a process drawing showing an example of a method of manufacturing a circuit board with a thick film resistor according to the present invention.

First, a flat ceramic green sheet 12 made of low-temperature sintered ceramics that can be co-fired with a conductor 4 described later.
Prepare g (Fig. 1 (A)). More specifically, this low-temperature sintered ceramic is used for the conductor 4 as described later in Ag-
When Pd or Cu is used, it should be sinterable at 1000 ° C or lower. One example of _{such, SiO 2 -BaO-Al 2 O} 3
There are ceramics.

And on the surface of this ceramic green sheet 12g,
For example, by a screen printing method, the paste-like conductor 4 containing Ag-Pd or Cu as a main component is printed in a pattern in which shrinkage of the fired ceramic substrate is taken into consideration (the same figure (B)).

After that, the product obtained in the above step is uniformly pressed by a rigid body press or a hydrostatic press to press the surface, and the conductor printed surface is smoothed while keeping the flat plate shape (FIG. 3C).

Then, the ceramic green sheet 12g obtained in the above process and the conductor 4 are co-fired to form a ceramic substrate 12 having the conductor 4 embedded on the surface (FIG. 3D).

Then, on the surface of the ceramic substrate 12 obtained in the above step, the cermet resistor _{6 of} RuO ₂ series or LaB ₆ series is formed by, for example, a screen printing method so as to extend between the conductors 4 and 4.
Is printed in a predetermined pattern ((E) in the figure), and then the resistor 6 is fired. As a result, a circuit board with a thick film resistor is obtained.

According to the above-mentioned manufacturing method, since the conductor printed surface of the ceramic substrate 12 is smoothed and then the resistor 6 is printed on the surface, there is no step due to the conductor 4 as in the conventional example, and therefore the resistor 6 is small (for example, small). Even if it is about 0.5 mm □ or less), the printability thereof is significantly better than that of the conventional example. As a result, for example, the proportion of the non-standard resistor 6 formed is reduced, and the yield of resistance formation is improved.

Moreover, in the above manufacturing method, the ceramic substrate 12 and the conductor 4 are
Since and are fired at the same time, the number of firing steps is reduced by one compared to the conventional example, and the cost can be reduced accordingly.

In the above example, the ceramic green sheet 12g or the ceramic substrate 12 is shown as a single plate, but they may be multilayer plates.

〔The invention's effect〕

 According to this invention, the following effects can be obtained.

Since the cermet resistor is printed on the surface of the ceramic substrate after the conductor printed surface is smoothed while maintaining the flat plate shape of the ceramic substrate, there is no step due to the conductor as in the conventional example, and therefore the resistor is small. However, the printability thereof is significantly better than that of the conventional example, and the resistor can be printed with high accuracy.

Since the ceramic substrate and the conductor are fired at the same time, the firing process is reduced by one compared to the conventional example, and the cost can be reduced accordingly.

Unlike the method of smoothing the surface by filling the step between the conductors with a photosensitive resist or the like, according to the present invention, the surface can be smoothed by a simple step of pressing and without using an extra material. it can. Moreover, since a photosensitive resist which is adversely affected by the firing of the cermet resistor is not used, a cermet resistor having good characteristics can be used as the resistor.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of a method of manufacturing a circuit board with a thick film resistor according to the present invention. FIG. 2 is a sectional view partially showing an example of a circuit board with a thick film resistor by a conventional manufacturing method. 4 ... Conductor, 6 ... Cermet resistor, 12g ... Ceramic green sheet, 12 ... Ceramic substrate.

Claims (1)

[Claims] 1. A step of preparing a flat ceramic green sheet and printing a conductor on the surface, and a step of pressing the material obtained in this step to smooth the printed surface of the conductor while keeping the flat shape. And a step of simultaneously firing a ceramic green sheet and a conductor of the one obtained in this step, a step of printing a cermet resistor on the surface of the one obtained in this step so as to extend between the conductors, and thereafter And a step of firing the cermet resistor, the method for manufacturing a circuit board with a thick film resistor.