JPH0464866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method of manufacturing a thermal head used in a thermal printer.

(Description of the Prior Art) Conventionally, two types of thermal heads have been widely used in thermal printers: thin-film thermal heads and thick-film thermal heads.
Thin-film thermal heads use vacuum equipment in their manufacturing process, making them difficult to mass produce.
This method has the drawback of high cost, and because the heating element is microfabricated by etching, the manufacturing yield is reduced.

On the other hand, since thick-film thermal heads are based on printing technology, the accuracy of the power feeder is determined by the accuracy of the mesh of the printing screen, which has the disadvantage that it is difficult to create fine patterns.

(Object of the invention) The object of the invention is to provide a high-precision thermal head,
It is an object of the present invention to provide a manufacturing method that is mass-producible, inexpensive, and has a high yield.

(Structure of the Invention) In order to achieve this object, the method of the present invention forms a power supply circuit pattern using photolithography technology, electroless plating technology, and electroplating technology, and then The gist of this paper is to form a heating resistor by thick film printing.

(Description of Examples) Hereinafter, examples of the manufacturing method of the present invention will be described with reference to FIGS. 1 to 6.

1 to 5 are process diagrams schematically showing states at main process steps as cross-sectional views for explaining one embodiment of the manufacturing process of a thermal head.

First, as shown in FIG. 1, a heat-resistant film having a plating catalyst film 2 adhered to its surface 1a is prepared as a substrate 1. The plating catalyst film 2 is a monoatomic layer or a film with a thickness close to it, and this catalyst is a catalyst for electroless plating, which will be described later, and metal palladium is preferable, but other materials may be used. Also good. Moreover, as the heat-resistant film 1, a polyimide film is suitable, but it is not limited to this.

A pattern of photoresist 3 is formed on this substrate 1 using a normal process. This photoresist 3 may be of either positive or negative type, and is left in the area where the heat generating resistor is to be formed and the area where the power feeder is not to be formed by a development process.

Next, the member formed as shown in FIG. 1 is immersed in an electroless plating bath to coat the photoresist 3.
Using this as a kind of mask, the electroless plating film 4 is formed only on the parts of the film 1 where the photoresist 3 is not formed, that is, the parts where the palladium film 2 is exposed. Since the electroless plating film 4 formed here constitutes a part of the power supply body of the thermal head, a plurality of these films 4 are formed on the film substrate 1, for example, in parallel and separated from each other.

Thereafter, the photoresist 3 is removed by a conventional method to obtain a member having the structure shown in FIG.
Note that this photoresist may be removed after the electroplated film 5, which will be described later, is formed.

Of course, the electroless plating bath used in this case can be a commonly known electroless copper plating bath or electroless nickel plating bath, but other suitable electroless plating baths may also be used. It is also possible to do this.

Next, as shown in FIG. 3, in order to lower the resistance value of the power supply, an electroplated film 5 is formed on the electroless plating film 4, and these two films 4 and 5 are used to form the power supply. 6. This electroplated film 5 is preferably formed of one or more of copper, nickel, solder, and gold, but is not limited thereto.

Next, a band-shaped heating resistor 7 as shown in FIG.
is formed by printing a thick film paste. A screen is used for this thick film printing, but the screen is positioned so that the screen mesh (the window or hole for printing the thick film paste) matches the location where the resist 3 described above was formed. Perform printing.

Conventionally, metal oxides such as ruthenium oxide have been used as this paste, but in the embodiment of the present invention, these metal oxides contain a binder and can be baked and hardened at low temperatures. However, the resistivity is almost the same as before.

Since this heating resistor 7 is formed into a band shape,
There is no need to miniaturize the thermal head itself, and therefore the manufacturing yield of the thermal head can be increased.

In the steps up to FIG. 4 described above, the power supply body 6 and the heating resistor 7 are formed on the polyimide film 1, and therefore, the heating portion which is an essential part of the thermal head is formed. Further, the pattern of the power supply body 6 and the planar band shape of the heating resistor 7 are determined by the pattern of the photoresist 3.

Next, as shown in FIG. 5, a cooling/supporting member 8 is attached and provided on the opposite surface of the substrate, that is, the polyimide film 1. This cooling/supporting body 8 can be suitably made of aluminum, iron, copper, or any other material with good thermal conductivity and suitable for supporting. Thereafter, the thermal head is completed by performing necessary treatments as necessary.

In the above-mentioned FIG. 5, the film 2 of the plating catalyst is shown to remain, but even if this film 2 remains, the insulation between the power supply bodies 6 is sufficiently maintained.

FIG. 6 is a perspective view schematically showing the heat generating portion of the thermal head manufactured in this manner. Fifth
As is clear from the figures and FIG. 6, according to this method of manufacturing a thermal head, a substrate 1 such as a polyimide film, and a band-shaped heating resistor 7 printed on the surface 1a of this substrate 1 are used. The substrate surface 1a includes a plurality of power supply bodies 6 formed separately from each other by electroless plating and electroplating, and each of these power supply bodies 6 generates the above-mentioned heat in a part thereof. A thermal head having a structure connected to the resistor 7 is obtained.

In the above-mentioned embodiment, the case where the power supply body 6 and the heating resistor 7 are formed on a heat-resistant film such as a polyimide film as the substrate 1 was explained, but instead of using a heat-resistant film, a ceramic substrate can also be used. . Even when this ceramic substrate is used as the substrate 1, it is necessary to adhere a plating catalyst such as palladium to the surface.

By the way, at present, this polyimide film coated with palladium is easily available as it is commercially available as Additive Polyimide Film (trade name), but the one coated with palladium on a ceramic substrate is not commercially available. Not yet. Therefore, a method for depositing palladium onto a ceramic substrate will be briefly described.

There is a method of vapor-depositing palladium onto a ceramic substrate, in which case palladium has strong adhesion but is expensive. Therefore, the immersion method can be considered. According to the immersion method, after immersing for 1 minute in a stannous chloride solution (stannous chloride 1g/, concentrated hydrochloric acid 1ml/), washing with water, and then immersing in a palladium chloride solution (palladium chloride 0.1g/, concentrated hydrochloric acid 0.1ml/). /) for 1 minute, then washed with water, and then placed in a nitrogen atmosphere.
Heat at a temperature of 500°C for 1 hour. Such a process allows palladium to be deposited on a ceramic substrate to a monoatomic layer thickness or close to it.

Incidentally, when a ceramic substrate is used as the substrate 1, it is not necessary to bond the cooling/supporting member 8 since it has a heat dissipating effect.

Further, when a ceramic substrate is used, a glass layer may be provided on the surface of the substrate as a heat insulating layer, and palladium or other plating catalyst may be deposited on top of the glass layer.

Although the dimensions, shapes, and arrangement relationships of each component of the thermal head manufactured by the method of the above-described embodiments can be arbitrarily selected according to the design,
The pitch of the power feeder is determined by the printing density.

(Effects of the Invention) As is clear from the above description, according to the method of manufacturing a thermal head according to the present invention, in forming a power supply pattern consisting of a plurality of power supply bodies separated from each other on the surface of a substrate, Electroless plating and electroplating techniques are applied, and the heating resistor is formed on the surface of the substrate by thick film printing, using conventional vacuum equipment and etching processes. Therefore, thermal heads can be mass-produced significantly more than before, and can be manufactured at a lower cost.

Furthermore, since photolithography technology is used to form the power supply pattern and no etching process is involved, it is possible to form even finer patterns (for example, 32 lines/mm) than in the past. The accuracy of the power feeder pattern is determined by the accuracy of the photoresist using the additive method.

Furthermore, since the heating resistor is formed into a band shape using thick film printing, there is no need to miniaturize the heating resistor itself, and therefore the manufacturing yield of thermal heads can be significantly higher than in the past. .

[Brief explanation of the drawing]

1 to 5 are manufacturing process diagrams for explaining the method of manufacturing a thermal head according to the present invention, and FIG. 6 is a schematic perspective view showing a heat generating portion of the thermal head manufactured by the method according to the present invention. 1...Substrate (heat-resistant film, ceramic substrate), 2...Plating catalyst film, 3...Photoresist, 4...Electroless plating film, 5...Electroplating film, 6...Power supply body, 7... heating resistor (thick film paste), 8... cooling/supporting body.

Claims (1)

[Scope of Claims] 1. A thermal head in which a power supply pattern consisting of a plurality of power supply bodies separated from each other is formed on a substrate, and then a heating resistor is formed so as to be connected to each of the power supply bodies. In the manufacturing method, a substrate having a film of a catalyst for electroless plating formed on its surface is used, and a photoresist pattern is formed on the substrate at a location where a heating resistor is to be formed and a location where a power supply body is not to be formed. forming an electroless plating film by performing electroless plating using the photoresist pattern as a mask; forming an electroless plating film on the electroless plating film by electroplating; Thereby, a step of forming a plurality of power supply bodies made of the electroless plating film and the electroplating film, and removing the photoresist pattern after forming the electroless plating film or after forming the electroplating film. 1. A method for manufacturing a thermal head, comprising the steps of: forming a band-shaped heating resistor to be connected to each of the power supply bodies by thick film printing.