JPS5953874B2 - Method for forming heating resistor of thick film thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a heating resistor of a thick-film thermal head by screen printing.

As shown in Figs. 1 and 2, the thick film thermal head has a large number of electrodes 2 formed on an insulating substrate 1, and generates Joule heat to transfer recording energy to thermal recording paper. These are formed by printing conductor paste or resistance paste on an insulating substrate 1 using a precision screen printing method, drying it, and then firing it. be.

On the other hand, factors that affect the printing quality of this thermal head include variations in the resistance value of the heating resistor 3 and the shape of the resistor.
In addition, it is necessary to print the heating resistor 3 with high precision. This often involves the use of metal masks using photolithography and plating techniques, rather than the emulsion masks with SUS mesh commonly used in screen printing. 1. FIG. 3 is a schematic diagram showing an example of the surface shape of the heating resistor 3 after printing and firing by aligning the electrode 2 and the mesh 5 formed on the metal mask 4. As shown in FIG. 3, when screen printing is performed with the mesh 5 placed approximately in the center between multiple electrodes 2, the surface shape of the heat generating resistor 6 after printing and drying is different from that directly under the mesh 5. It has a concave shape, and the upper part of the electrode 2 has a convex shape. Then, when firing, the organic binder in the thick film paste decomposes and shrinks in volume to form the heating resistor 3, but its surface shape remains convex on the electrode 2 as before firing. The surface roughness is 5 to 10
It becomes μm. FIG. 4 shows a state in which recording is performed by pressing the heat-sensitive recording paper 7 with a roller (not shown) against the heating resistor 3 formed in the above manner. In this case, the heating resistor 3 involved in recording is placed between the electrodes 2,
In other words, this is a concave area, but because of the concave shape, the thermal recording paper 7 does not come into close contact with the heating resistor 3θ, resulting in insufficient Joule heat transfer, resulting in poor print quality. Ta. Further, there was a problem in that the unevenness of the surface of the heating resistor 3 left impressions on the thermal recording paper 7. SUMMARY OF THE INVENTION An object of the present invention is to provide a screen printing method that smoothes the surface of a heat generating resistor in order to eliminate the above-described drawbacks of the prior art and improve the quality of printing by a thick film thermal head. In order to achieve the above object, the present invention uses a metal mask having a mesh of the same pitch as a large number of electrodes for the heating resistor of a thick film type thermal head, and this mesh is used as an electrode which has already been formed on an insulating substrate. It is formed by aligning a metal mask so that it is directly above the screen, performing screen printing, and then firing. below,
An embodiment of the method for forming a heating resistor of a thick film thermal head according to the present invention will be described with reference to FIG.

In the figure, the mesh 5'' of the metal mask 4'' is formed at the same pitch as the multiple electrodes 2 on the insulating substrate 1, and the metal mask 4'' is set on a screen printing machine (not shown). Then, position the mesh 5'' so that it is directly above the electrode 2. This positioning state can be determined by printing using a highly viscous resistance paste and checking whether the concave portions at the bottom of the mesh match the electrodes. When screen printing is performed in such a state, the heating resistor 6'' after printing and drying becomes convex in the middle between the electrodes 2 because the mesh 5'' is directly above the electrodes 2. Although volume shrinkage occurs after firing, the surface roughness of the heating resistor 3'' is within 1 to 3 μm, which is almost smooth.As described above, according to the present invention, the thick film type thermal head When forming a rod-shaped heating resistor by screen printing in the manufacturing of Since the surface of the heat-sensitive recording paper is always smooth, there is good adhesion between the heat-sensitive recording paper and the heating resistor during recording, and the printing quality can be improved.

[Brief explanation of drawings]

Fig. 1 is a partial plan view of a thick film type thermal head, Fig. 2 is a side sectional view of Fig. 1, and Fig. 3 is a partial plan view of a thick film type thermal head.
FIG. 4 is a schematic diagram showing a cross section of a mask and a heating resistor, FIG. 4 is a diagram showing a state of contact between a heating resistor and thermal recording paper according to the prior art, and FIG. FIG. 3 is a schematic diagram showing a cross section of a mask and a heating resistor. Explanation of symbols 1... Insulating substrate, 2... Electrode, 3, 3
″...heating resistor, 4,4″...metal mask,
5,5″...mesh, 6,6″...heating resistor (
After printing and drying), ...thermal recording paper.

Claims (1)

[Claims] 1. A heating resistor in a thick-film thermal head comprising a large number of electrodes formed in parallel to each other on an insulating substrate, and a heating resistor formed in the shape of a bar approximately perpendicular to the electrodes. , using a screen printing metal mask with a mesh of the same pitch as the electrode;
A method for forming a heating resistor for a thick-film thermal head, characterized in that the heating resistor is formed by screen printing with the mesh of the mask positioned directly above the electrode.