JPH0632929B2 - Method of manufacturing thermal head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head, and in particular, a plurality of heating resistor elements are linearly arranged on the same substrate and the heating resistor elements are arranged according to information to be recorded. The present invention relates to a thermal head in which an element is energized and heated to color-record on a thermosensitive recording paper or transfer recording is performed on plain paper via an ink ribbon.

[Conventional technology]

As shown in FIG. 4, the general structure of the thermal head is that an insulating substrate 1 is provided with a partial glaze layer 2 having a substantially arcuate cross section, and a heating resistor layer 3 is laminated thereon. A conductor layer 4 made of aluminum or the like is formed on the heating resistor layer 3, and an oxidation resistant layer 5 is further formed on the conductor layer 4.
A wear resistant layer 6 is laminated. By removing a part of the conductor layer 4 on the partial glaze layer 2, the conductor layer 4 becomes a power supply electrode, and the portion of the heat generating resistor layer 3 from which the conductor layer 4 is removed becomes a heat generating portion 3 '. Since the terminal portion of the conductor layer 4 has poor solderability with aluminum, the surface of the terminal portion is plated with an easily solderable metal (for example, tin or tin alloy).

As a conventional method for forming the terminal portion 10 in the thermal head, as shown in FIG.
Using the n-substituted plating solution, the thermal head having the conductor layer 4 formed thereon is dipped into a commercially available plating solution to form a Zn substitution layer while substituting aluminum, and further Ni plating is performed by electroless plating, and Sn or Sn alloy is electrolytically plated on the Ni plating layer to form a terminal having good solderability.

[Problems to be solved by the invention]

In such a conventional thermal head, the conductor layer 4
Has a very low density of 1.5 to 2.0 μm, and therefore has a lower density than the bulk. Also, since the substrate is an alumina substrate, the surface of the conductor layer 4 has severe irregularities.
The etching rate of the 1-conductor layer is high.

Further, when the treatment is carried out by the commercially available Zn substitution plating method as shown in FIG. 3, it is necessary to form the Zn layer by performing the dipping for about 1 minute twice twice in order to form the Zn layer densely.
This is because the Zn-substituted film formed by one-time dipping has coarse particles and adheres like islands and is poor in denseness. This is because it is known that a good Zn film can be formed.

As described above, the Al conductor layer is also etched twice by performing the etching twice.
The Al layer having a thickness of 1.5 to 2.0 μm may almost disappear and the resistor layer may be exposed, and the problem of poor adhesion strength of Ni plating is likely to occur. The problem of poor adhesion strength of Ni plating is likely to occur. Therefore, when forming the terminal portion with a conductor layer having an Al single layer structure, the Al film thickness is required to be at least 2 μm.

In this way, it is necessary to form the Al conductor layer thick, and in that case, as shown in FIG. 4, the Al conductor of the head heating portion is 2 μm.
It becomes a projecting part of m and the dent of the heat generating part 3'becomes large. Therefore, the pressure contact with the thermal recording medium is weakened, and good quality cannot be obtained unless the applied energy is increased. In FIG. 4, 7 is a Ni plating layer, 8 is a Sn plating layer, 9 is a head surface, and 10 is a terminal portion.

The present invention has been made in view of the above problems, and an object of the present invention is to form a thin film of the Al conductor layer by changing the method for manufacturing the plating of the terminal portion made of the Al conductor layer. However, it is still another object of the present invention to provide a method for manufacturing a thermal head having a high manufacturing yield without abnormalities in the plating quality of terminals.

[Structure of Invention]

In order to achieve such an object, the method of manufacturing a thermal head of the present invention uses the conventional terminal plating process in which N
It is characterized in that a heat treatment after i plating is added.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, after a glaze layer 2 is partially formed on an alumina substrate 1, Ta is deposited on the glaze layer 2 in an amount of 0.05 to 0.05 by a reactive and sputtering method of Ar and N ₂ gas.
Heating resistor layer 3 having a thickness of 0.2 μm and made of Ta ₂ N
To form. Next, a conductor layer 4 made of Al having a thickness of about 1 μm is provided, and a pattern of a heating resistor portion and a conductor portion is formed by the photolithography technique, and the terminal portion 10 is masked to form a SiO ₂ film having a thickness of about 2 μm. the wear-resistant layer 6 of Ta ₂ O ₅ oxidation layer 5 and about 5μm thick is formed by Supatsutaringu, fabricating a head face 9.

Next, in the process shown in FIG. 2, the Al layer in the area of the terminal portion 10 is selectively dipped twice in a Zn replacement solution (trade name: Bondal solution), and then electroless Ni plating is performed to form the Ni layer 7. It is formed on the entire surface of the terminal with a thickness of about 2 μm. Then, after drying with cleon, etc., in a belt furnace at 150 ° C. for 5 minutes, 2
1 minute at 00 ℃, 30 seconds at 250 ℃, 10 minutes at 300 ℃
Heat treatment is performed under any condition for 1 second. After a while N
The i layer is surrounded, Sn is formed by electrolytic plating, the terminal part 10 is manufactured, and it connects with an external circuit (not shown).

According to this embodiment, the conductor layer 4 on the head surface 9 is made of Al or A.
Since it is formed as thin as 1 μm by the single layer vapor deposition of 1-alloy, the film forming material, the film forming time, and the maintenance time can be reduced.
Also, most of the 1 μm Al conductor disappears due to Al etching at the time of Zn substitution, but at that time, since H ₂ gas generated when Al dissolves in the etching liquid has a strong reducing action, the failure of the resistor layer 3 is impaired. The dynamic film is removed and electroless Ni
It exhibits the property that Ni is very likely to adhere in the plating solution. At first glance, it seems that good Ni plating was formed in this state, but the adhesive force between Ta ₂ N and Ni is very weak. However, it has been found that when this is heated under the above-mentioned heating conditions, the adhesion is remarkably improved and the strength is remarkably maintained as compared with the conventional case without heat treatment of Al / Zn / Ni.

This heat treatment shows a remarkable effect even in the case of the conventional Al / Zn / Ni, and Al disappears in the terminal portion 10 and Ta ₂ N
However, even if Al remains, the adhesive strength is remarkably high. Also, heating in air after Ni plating may cause an oxide film on the Ni surface to reduce the plating property such as Sn plating, but under the above-mentioned heating conditions, no abnormality occurs at all. As a result of experiments, it was found that the adhesion strength of the Ni plating, which is likely to be stable, can be remarkably stabilized.

〔The invention's effect〕

As described above, the present invention uses the lowest cost Al as the conductor material, and even if the Al film thickness of the terminal portion is about half that of the conventional one, the conventional plating process is performed at 150 to 300 ° C. after the electroless Ni plating. By adding the heat treatment under the temperature condition, Ni is added to both Ta ₂ N and Al.
The adhesion of the beetle can be extremely stabilized.

Even if the film thickness of the Al conductor is reduced as described above, the terminal portion can be formed easily and reliably.
Printing energy can be reduced due to cost reduction due to a drastic reduction in maintenance time, and thermal efficiency up due to a drastic increase in the amount of protrusion of the heat generating portion that sensitively affects printing quality. Further, since the step of the heat generating portion is reduced, there is a practical effect that variations in mechanical strength are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a thermal head showing an embodiment of the present invention, FIG. 2 is a manufacturing process drawing of the thermal head of the present invention, and FIG. 3 is a manufacturing process drawing of a conventional thermal head. FIG. 4 is a sectional view of a conventional thermal head. 1 ... Alumina substrate, 2 ... Partial glaze layer, 3 ... Resistor layer, 3 ... Heat generating part, 4 ... Conductor layer, 7 ... Ni plating layer, 8 ... Sn plating layer, 9 ... Head side, 10 ...
… Terminal part.

Claims (1)

[Claims] 1. A glaze layer is provided on an insulating substrate, a heating resistor layer is formed on the glaze layer, a conductor layer made of aluminum or an aluminum alloy for supplying power to the heating resistor layer, and these heating resistor layers. A thermal head having a structure in which a conductor film and a protective film for protecting the conductor layer are laminated, and a base plating layer made of nickel or nickel alloy is formed at a terminal portion of the conductor layer, and then the temperature is set to 150 to 300 ° C. A method for producing a thermal head, characterized in that a heat treatment is performed under the conditions, and a low melting point metal layer having solderability is formed on the underlying plating layer.