JPS643667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a thermal print head.

As is well known, this type of thermal print head is constructed by forming a pair of wiring layers on the surface of an insulating substrate, and then forming a heat generating layer spanning both wiring layers. Therefore, the ends of the wiring layer and the ends of the heat generating layer overlap each other. However, the wiring layer is usually made of gold or the like, and the heat generating layer is made of ruthenium oxide, etc., and both are formed by printing and firing, so the overlapping parts of the two do not blend into each other, that is, the two do not become integrated. It is extremely difficult. Therefore, delamination is likely to occur between both layers, and especially when pulsed voltage is repeatedly applied to generate heat, rapid heating and cooling will be repeated, resulting in noticeable delamination and floating separation between the layers. do.

An object of the present invention is to ensure reliable integration of a wiring layer and a heat generating layer in the overlapping portion thereof.

In this invention, in the overlapping region of the wiring layer and the heat generating layer,
A fusing layer made of lead or a compound thereof is interposed to fuse the two, and by heating this, the lead component in the fusing layer is removed from the binder glass contained in the wiring layer and the heat generating layer. It is characterized by ensuring reliable integration in the overlapping region of the wiring layer and the heat generating layer by diffusing the wiring layer and the heat generating layer.

An example method of the present invention will be explained with reference to the drawings. 1 is an insulating substrate such as alumina ceramic, 2 is a pair of wiring layers made of gold or the like, and 3
is a heat generating layer made of ruthenium oxide or the like, and is formed so as to overlap the ends of both wiring layers 2. The wiring layer 2 is formed by printing and baking. After forming this, the heat generating layer 3 is also formed by printing and baking. Such a forming method is not particularly different from the conventional method. In such a configuration, as described above, peeling easily occurs in the overlapping region of the wiring layer 2 and the heat generating layer 3.

According to the present invention, prior to forming the heat generating layer 3, a fusion layer 4 made of lead or a compound thereof (for example, lead oxide) is formed at the end of the wiring layer 2, that is, in a region overlapping with the heat generating layer 3. Fusion layer 4
Actually, a glass paste containing at least 30% of lead or its compounds is printed and fired (film thickness).
(approximately 0.1 to 5 μm) or formed into a film (film thickness approximately 0.1 to 3 μm) by vacuum evaporation or the like.

After this, the heat generating layer 3 described above is printed and fired, and naturally the heat generating layer 3 is the wiring layer 2.
The adhesive layer 4 is printed in such a manner that the adhesive layer 4 is interposed in the overlapping region. After this printing, it is fired at around 700-950℃. The heat of firing at this time heats the fusing layer 4 and the wiring layer 2 at the same time, but this heat causes the lead component in the fusing layer 4 to coexist as a binder in the wiring layer 2 and heat generating layer 3. Diffuses into glass (generally leaded glass). Due to this diffusion, a region containing a large amount of lead is integrally formed between the wiring layer 2 and the heat generating layer 3, and as a result, the wiring layer 2 and the heat generating layer 3 are placed between the wiring layer 2 and the heat generating layer 3 through this diffusion region. They are now integrally fused and bonded.

Next, an experiment conducted by the present inventor will be explained.
When a pulse voltage with a duty factor of 50% and a peak value of 15V was continuously applied, local peeling occurred after 3 x 10 pulses were applied to a conventional thermal print head. In contrast, according to the present invention, a glass paste containing 35% lead oxide is printed and fired to form a fusion film 4 with a thickness of 3 μm, and then a heat generating layer 3 is printed and fired (firing temperature: about 800°C). When the film was formed to a thickness of 2 μm, no peeling occurred anywhere even when the pulse voltage described above was continuously applied 10×10 ⁸ times under the same conditions.

As detailed above, according to the present invention, the overlapping region of the wiring layer and the heat generating layer is integrated through the glass layer with a high lead content, so that the fusion of the two is reliable, and rapid heating and cooling can be achieved. This has the effect that accidents such as peeling and floating can be sufficiently avoided.

[Brief explanation of the drawing]

The figure is a sectional view showing the process of carrying out the method of this invention. 1... Board, 2... Wiring layer, 3... Heat generating layer, 4
...Fusion layer.

Claims (1)

[Claims] 1. Form a pair of wiring layers on the surface of a substrate, then form a fusion layer made of lead or a compound thereof on each opposing end of the wiring layer, and then apply the fusion layer between both wiring layers. Manufacturing a thermal print head by printing a heat generating layer with a fusing layer interposed therebetween and heating and firing it to such an extent that the lead component in the fusing layer diffuses into the wiring layer and the binder glass in the heat generating layer. Method.