JPH02198872A - Trimming method of resistor of thermal head - Google Patents

Abstract

PURPOSE:To heat, burn and remove only the abnormal shape section of a resistor without damaging a conductor pattern by irradiating the abnormal shape section of the resistor formed onto the conductor of a thermal head substrate with infrared laser beams or carbon dioxide laser beams passed through two pinholes shaped with an interval corresponding to the line width of the resistor. CONSTITUTION:Infrared laser beams 4 are converted into two small spot-beams 6 by the two pinholes 5a, 5b of a pinhole plate 5. The two pinholes on the pinhole plate are formed fundamentally at an interval corresponding to the line width of a resistor 7 on a thermal head. The bores of the pinholes are brought normally to 300-500mum, and are sufficient when they are made larger than the sag and bleeding sections of the resistor 7. The spot-beams 6 of the laser beams are moved along the resistor 7 in a shape that the resistor is held by the spot-beams 6, and the abnormality of the form of the resistor 7 is removed as shown in a trimming trace 10. Accordingly, the shape of the resistor can be trimmed without damaging a conductor pattern, thus correcting the dispersion of a resistance value affecting the quality of printing.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for trimming a resistor formed on a conductor in a thermal head, and particularly relates to a method for trimming a resistor formed on a conductor in a thermal head. It is used in the manufacturing process of heads, etc.

(Prior Art) As a conventional technique for trimming a resistor of a thermal head, a pulse trimming method is performed in which a pulse voltage is applied and dielectric breakdown of the resistor is utilized.

(Problem B to be solved by the invention) However, the above-mentioned pulse trimming method can only correct the resistance value by reducing it, and the amount of correction is also limited by the paste components, and the limit of the amount of resistance value correction is about 20 to 40%. , and it was not possible to modify the shape.

Furthermore, YAG (YTTRIυM-
ALUMINUM-GARNET) Trimming with a laser beam also poses a risk of damaging the conductor when the resistor shape is a thermal head because it is thin, and there is no trimming space when using a YAG laser beam.

The technical object of the present invention is to provide a method for trimming a resistor of a thermal head to eliminate irregularities in the shape of the resistor that affect the print quality of the thermal head and to correct variations in resistance value.

[Structure of the invention]

(Means for solving the problem) The technical means taken to solve the above problem are as follows. That is, irradiating the abnormally shaped portion of the resistor formed on the conductor of the thermal head board with infrared laser light or carbon dioxide laser light that passes through two pinholes provided at an interval corresponding to the resistor wire width. This is a method of trimming the resistor of a thermal head that heats and burns only the abnormally shaped portion of the resistor to remove it without damaging the conductor pattern.

(Function) By irradiating the abnormal shape of the print on the thermal head with infrared laser light or carbon dioxide laser light through a small pinhole and moving it along the resistor, abnormalities in the resistor can be eliminated. be.

Further, since a gold conductor is used for the conductor portion and has a high reflectance to infrared rays, by adjusting the laser output, it is possible to efficiently heat and burn only the resistor without damaging the gold conductor.

(Example) Examples will be described below.

The thermal head substrate has a gold conductor pattern formed by printing and etching on a ceramic substrate whose surface is coated with glass.

The resistor is formed at a predetermined position on the conductor pattern by screen printing. This is shown in FIG. 1, where 1 is a gold conductor and 2 is a resistor.

In some cases, the resistance paste drips or bleeds, and this is shown in FIG. 2, where 3 indicates an abnormal part of the sag or bleed.

The print quality of the thermal head, that is, the unevenness of print density during printing, is caused by the variation in resistance value, and the abnormal shape 3 of the resistor 2 as shown in Figure 2 is a resistance value that directly affects the variation in resistance value. (becomes smaller), reducing print quality.

Since the conventional pulse trimming method is a modification technique that reduces the resistance value, it cannot be used for modification in the above case.

In this embodiment, the abnormal shape of the resistor caused by dripping or bleeding of the resistor paste is heated and burned using infrared laser or carbon dioxide laser light to eliminate it, adjust the shape, and improve printing quality.

FIG. 3 shows this embodiment, in which an infrared laser beam 4 is converted into two small spot beams 6 by two pinhole holes 5a and 5b of a pinhole plate 5.

The two pinholes on the pinhole plate are basically provided at an interval corresponding to the line width of the resistor 7 on the thermal head. The diameter of the pinhole is usually 300 to 500 μm, and it is sufficient that it is larger than the sagging or bleeding portion of the resistor 7. Note that 8 is a gold conductor and 9 is a substrate.

By moving the resistor 7 along the resistor 7 in such a way that it is sandwiched between the spot beam 6 of this laser light, the resistor 7 is
The shape abnormality is removed as shown in the trimming trace 10 in FIG. 4.

Also, since gold conductors have a high reflectance for infrared rays,
Adjust the laser power to the minimum amount needed to remove the resistor without damaging it.

On the other hand, black objects such as resistors efficiently absorb infrared rays, are heated and burned, and are eliminated.

As described above, according to this embodiment, it is possible to trim the shape of the resistor without damaging the conductor pattern, and it is also possible to correct variations in resistance value that affect print quality.

〔Effect of the invention〕

The present invention has the following effects. In other words, since the present invention uses infrared laser light, it has a high reflectance even when irradiated onto the gold conductor, so only the abnormal part of the resistor with high absorption can be trimmed without causing damage to the conductor. .

In addition, since there is no limit to the amount of correction as in pulse trimming for trimming the shape of the resistor, the correction ability is extremely large.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a normal printed state of a resistor, Fig. 2 is an explanatory diagram showing an abnormal printing state of a resistor, Fig. 3 is an explanatory diagram of this example, and Fig. 4 is an explanatory diagram of the corrected resistor. FIG. 1... Gold conductor. 2...Resistor. 3... Abnormal part. 4...Laser light. 5a, 5b...pinhole holes.

Claims (1)

[Claims] By irradiating the abnormally shaped portion of the resistor formed on the conductor of the thermal head board with infrared laser light or carbon dioxide laser light that passes through two pinholes provided at an interval corresponding to the resistor wire width, A thermal head resistor trimming method that heats and burns only the abnormally shaped portion of the resistor to remove it without damaging the conductor pattern.