JPH02276651A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent short circuit due to flow out of solder from one wiring to another wiring, upon thermal adhesion of circuits, by forming a band of solder narrower than the width of a second electrode onto a first electrode thereby jointing the first and second electrodes through the solder band. CONSTITUTION:Tantalum nitride film is stuck through magnetron sputtering onto a partially grazed Alumina substrate. Furthermore, a Cr-Cu-Cr layer is vacuum deposited thereon, then heating sections and electrodes are photoetched. At section A, a common lead electrode(end section of wiring) is splitted into two sections and a slip 6 is etched. Then an anti-oxidation SiO2 layer and an anti-abrasion Ta2O5 layer are deposited through sputtering onto the upper section of the head except the soldered section, thereafter the head is immersed into a solder tank thus dipping the head in solder. When joint is made with a flexible circuit through thermal pressure joint system where heat is applied from the lower section and pressure is applied from the upper section, leakage of solder is reduced and contact with other electrodes can be prevented.

Description

[Detailed description of the invention] The present invention relates to a lead electrode shape of a thermal head.

An object of the present invention is to facilitate the connection between the head and a flexible circuit by providing slits or hollows in the lead electrodes of a micro-miniature thermal head.

Another object of the present invention is to provide a thermal head that is extremely small and can be manufactured at low cost.

A thermal printer, which is one of the typical non-impact printers, produces less noise when printing.

A large number of these methods have appeared due to their advantages such as ease of handling as they do not require development or fixing, simple mechanism with few moving parts, and relatively low cost of recording paper. Thermal printers with these features are progressing toward becoming even more compact and cost-effective, but the biggest of the 6 problems that have not yet been resolved is the connection between the thermal head and the flexible circuit. It is. The head itself has been developed through the development of microfabrication technology.
Although ultra-compact size became possible, the method of connecting the small head to the circuit was extremely difficult and costly. More details will be explained with reference to the drawings. FIG. 1 is a schematic diagram of a conventional thermal head. Solder is attached to the lead electrodes shown in FIG. 1 for connection to a flexible circuit.

This solder is deposited in a solder dip bath due to its low cost and stability in mass production. Therefore, the amount of solder deposited is naturally determined by the lead shape and width. FIG. 2 shows a cross-sectional view of the amount of solder deposited on the lead portion in the conventional case.As shown in FIG. 2, the amount of solder deposited on each lead is different from the amount deposited on the common lead.

If a connection is made to the flexible circuit by thermocompression bonding in this state, the amount of solder leaking from the common lead will be larger than that from the other leads, reaching the adjacent leads and causing a short circuit. This has led to a significant decrease in yield and increased costs.

To solve this problem, several methods have been used in the past, but none are good.For example, if you increase the distance between the leads without changing the width of the leads, the head itself becomes larger and becomes ultra-compact. It is not possible, and if the width of the leads is reduced without changing the distance between the leads, the resistance of the leads will increase.

The present invention makes it possible to solve the above-mentioned problems without changing the current production method.

Hereinafter, the present invention will be explained using examples and figures.

Example 1 A nitride tank film is deposited by magnetron sputtering on an alumina substrate on which a partial glaze has been formed.

Furthermore, a layer of Cr--Cu--Cr was deposited on this film by vapor deposition, and the heat-generating portion and electrodes were processed using a photoetching method. The shape obtained by this method is shown in FIG.

The most important point of the present invention lies in the shape of part A in FIG. On the top of this head, a 5in2 oxidation-resistant layer is applied, excluding the solder attachment part.
The axes wear layer was deposited by sputtering. After that, it was placed in a solder tank and solder was applied using the dip method. The connection to the flexible circuit [hair styling uA (whole body is made of polyester) 1 was performed using a thermocompression bonding method in which heat is applied from the bottom and pressure is applied from the top. FIG. 4 shows a cross-sectional structural diagram (a) of the present invention and a conventional cross-sectional structural diagram (b),
(b) As shown in the figure, in the conventional method, a large amount of solder leaks and comes into contact with other nearby electrodes. In the head of the present invention, there is no leakage amount of solder to the slit portion as shown in Figure (b).

Therefore, there is no short circuit with other electrodes like in the past, and the yield of connecting the head and flexible circuit is 100%.
become.

Example 2 A thermal head was produced in the same manner as in Example 1. The shape of the common electrode at this time is shown in FIG.

The present invention as shown in the embodiments above facilitates the connection between a flexible circuit and an ultra-small head by providing a slit or a hollow in the common electrode, and also makes it possible to reduce costs. 0 Example 1
The slit shape is shown in the figure, but there is no particular limitation on the slit width and position. Also, regarding this Example 2, an example of the shape is shown in FIG. There are no limitations on the size or shape of the area.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional thermal head. FIG. 2 is a cross-sectional view of a conventional thermal head with solder attached to the lead T4 pole portion. FIG. 3 is a diagram showing the shape of the electrode with slits used in Example 1. FIGS. 4(a) and 4(b) are cross-sectional structural views of electrode parts in which a conventional thermal head and a thermal head of the present invention are connected to a flexible circuit by thermocompression bonding. FIG. 5 is a diagram showing the shape of the electrode used in Example 2. Heat generating part common lead electrode solder individual lead electrode board slit flexible circuit hollow part Figure 5

Claims (1)

[Claims] In a thermal recording head, in which a heating element and its power supply section are provided on a heat dissipation substrate, and required recording is performed on thermal recording paper by the heat generated by the heating element when electricity is supplied from the power supply section, an end of the power supply section is provided. A thermal head that is characterized by having a slit or hollow hole in the section.