JPS6149802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a resistor obtained by a printing method, and provides a highly reliable resistor.

Generally, thick-film resistors printed on ceramic substrates such as alumina and holsterite are trimmed to adjust their resistance to a specified range. There are two methods: a sandblasting method in which the resistor is cut by ejecting it, and a laser trimming method in which a portion of the resistor is removed by laser irradiation. In the latter case, the processing time for resistor adjustment can be significantly shortened, and there is also the advantage of being able to adjust fine, high-density resistor patterns that require miniaturization of circuits. For this purpose, laser trimming has been mostly used in recent years. Further, the resistor is usually overcoated with a protective film such as glass, but since the resistance value changes during the overcoat baking process, the above-mentioned resistance adjustment is usually performed after the overcoat.

However, in conventional resistance adjustment by sandblasting or laser trimming, the resistance cut cross section 2' is exposed in the resistance film 2 printed and fired on the alumina substrate 1 and the glass overcoat 3 as shown in FIG. Since the resistor in this exposed part is not completely overcoated, it is exposed to the outside air and is susceptible to chemical and mechanical effects from exterior resin and other materials that come into contact with the outside, resulting in changes in resistance. or cause variation. For this reason, there were many difficulties in management, such as limiting the dimensions of the exposed parts by cutting to a minimum and sorting them out. In addition, in laser trimming, attempts have been made to adjust the resistance value by weakening the laser irradiation and changing the material mainly by oxidizing the resistor, but this increases the resistance adjustment time and also reduces the temperature coefficient and other characteristics. There are drawbacks that change.

The present invention eliminates the above-mentioned drawbacks and provides a resistor with a completely overcoated protective coating.
This method of manufacturing a resistor is characterized in that resistance is adjusted by laser trimming to remove the film resistor without removing the protective film.

Hereinafter, explanation will be given with reference to the drawings. FIG. 2 shows a plan view of an L-cut cut groove of a resistor that has been laser trimmed, and FIG. 3 shows an enlarged cross-section of the cut groove according to the present invention. The resistor 2 printed on the ceramic substrate 1 is overcoated with a protective film 3 made of glass or the like, and this is cut by laser trimming as shown in FIG. 3 to form the cut portion 2' of the resistor 2. This prevents it from being exposed to the outside. 4 is an electrode. To explain the cutting situation, as the laser power is gradually increased,
It first begins to affect the resistor 2, then melts the protective coating 3 and cuts the resistor 2, resulting in the state shown in FIG. In this case, the protective film 3 does not evaporate and covers the resistor 2. If you further increase the power, the protective coating 3
After evaporating, the result is as shown in Figure 1. This protective film is melted and solidified, and a state in which the protective film 3 completely overcoats the resistor 2 can be completed.

The present invention performs laser trimming to obtain the state shown in FIG.
Figure 4 shows a comparison curve of humidity load life characteristics at 70°C with Ω and 125mW. The resistor of the present invention can provide a resistor that is more stable and reliable than conventional resistors.

Although the description has been given of a thick film resistor formed by a printing method, the present invention is also effective for thin film resistors formed by a vapor deposition method and other films having a protective film.

As described above, since the laser trimmed state of the resistor according to the present invention can be observed, it is easy to set the laser trimming conditions and judge the quality after resistance adjustment using a stereomicroscope, which makes management easier. It has the feature that it is possible to obtain a highly reliable resistor as described above, and is of great industrial and practical value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cutting groove obtained by trimming a conventional printed resistor, FIGS. 2 and 3 show an embodiment of the present invention, FIG. 2 is a top view of the printed resistor, and FIG. 4 is a cross-sectional view of the groove cut by laser trimming, and FIG. 4 is a characteristic diagram of a humidity resistance load life test of a resistor comparing a product of the present invention and a conventional product. DESCRIPTION OF SYMBOLS 1: Substrate, 2: Printed resistor, 2': Exposed part of resistor, 3: Protective coating, a: Resistor of the present invention, b:
Conventional resistor.

Claims (1)

[Claims] 1 In a method for manufacturing a resistor in which a film resistor is formed on an insulating substrate, a protective film is formed on the film resistor, and the resistance is adjusted by laser trimming, the protective film in the trimmed portion is melted to form a resistor. 1. A method for manufacturing a resistor, which comprises cutting the body and solidifying the body to cover the cut portion.