JPS6122964A - thermal head - Google Patents

Abstract

PURPOSE:To equalize printing recording density, and to obtain a small-sized thermal head, recording dusts therefrom are reduced and cost thereof is low, by forming a discrete conductor in a region connected to a heating resistor by an oxidizing thin-film metal and shaping other regions by a thick-film metal while protecting the thin-film metal and the resistor by a thin-film-shaped insulating film. CONSTITUTION:Thick-film metallic condustors 22 and 23 are attached and formed onto a substrate 21 in a desired shape. A thin-film resistor 24 and an oxidizing thin-film metal 25 are applied continuously in a desired region on the substrate. A thin-film metal and a heating resistor film are shaped according to patterns in succession, and an insulating protective film 26 is attached onto the substrate. Since the heating resistor film and the thin-film metal are applied continuously, a manufacturing process is shortened, and cost is reduced. Since a thick-film metal and a heating resistor can shape a compound, the heating resistor film fast sticks to the thick-film metal excellently. Accordingly, a small-sized thermal head and uniform printing recording density are acquired, and paper dusts with recording are also reduced because stepped sections among the resistor and the conductors are minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductor configuration of a thermal head, and particularly relates to a resistance retaining material that makes the printed recording density uniform and has good contact with a heating resistor or a conductor connected to the resistor. The object of the present invention is to provide a miniaturized thermal head that has a layer and has less recording debris that adheres to the thermal head during print recording.

Conventionally, in thermal heads in which multiple JCs are mounted on a wiring board, the individual conductors connected to the heating resistor and extending to the bonding terminals of the IC are made of a thin film material such as aluminum, gold, or copper. When formed, as described in Japanese Patent Application No. 58-185428, for example, the thin film material has low crystallinity and therefore has a high specific resistance, so that the individual conductor has a conductor resistance correction region with a narrower width than the part in contact with the resistor. It was necessary to establish a In other words, for individual conductors where the distance between the bonding terminal and the heat generating resistor is short, the conductor resistance correction area is made longer to increase the conductor resistance, and the value is made equal to the conductor resistance of the individual conductor with the longest distance. Therefore, it was necessary to equalize the print density of the thermal head.

However, as the resolution of the heating resistor increases and the width of the individual conductors narrows, the area for correcting the conductor resistance inevitably becomes wider. If it was provided only in the individual conductor portions, it was not possible to sufficiently correct the conductor resistance of the individual conductors. Therefore, it was previously proposed to provide the conductor resistance correction area on both sides of the rectangular conductor branching from the common electrode across the heating resistor and on the individual conductor side of the IC mounting section.

A thermal head having such a wide conductor resistance correction area therefore has a wide substrate, and thus manufactured thermal heads are large and expensive.

As a method for eliminating such defects, for example, the individual conductors may be made of gold, silver, copper, or platinum having a thickness of about 2 to 10 μm and having low resistivity or low area mechanical strength.

There is a method of forming the conductor using a thick film conductor or a plated conductor made of palladium or a material made of a mixture of these metals.

However, the metals mentioned above are basically non-oxidizing metals, or the oxides formed lack adhesion to the base material. The thin film heating resistor protective layer had poor adhesion to the metal and could not mechanically protect the heating resistor 5 sufficiently. That is, as the insurance layer, an insulating material such as silicon dioxide, silicon nitride, silicon carbide, tantalum pentoxide, etc. is deposited on the substrate by sputtering or vapor deposition. These materials are basically physically bonded to the underlying material through an oxide. Therefore, if a stable oxide is not formed on the metal, the insulating material deposited on top of it will naturally be bonded to the underlying material. adhesion becomes poor. For this reason, the insulator on the conductor easily peels off from the metal, and the cracks that occur at this time also cause poor adhesion of the insulator on the resistor.

Therefore, in the thermal head using gold Di,
As the insulator, a thick film insulator formed by a printing method or the like is generally used, and the heating resistor is also generally a thick film resistor due to compatibility with the manufacturing process. However, thick-film heating resistors have poor thermal response characteristics and are not suitable for high-speed layout printing. Therefore, if a thin film heating resistor is desired,
The insurance layer must be a thin film of insulator, and the insulator is deposited after an oxidizing metal such as titanium, chromium, nichrome, etc. is deposited on the thick film metal.

Therefore, the manufactured thermal head has the drawback of being expensive due to the long manufacturing process.

Furthermore, when the recording paper to be printed and recorded by the heat-generating resistor is thermal paper, the chemical material melted by the coloring is removed from the recording paper by the step between the heat-generating resistor and the conductor connected to the heat-generating resistor. It has the property of being peeled off and attached to the thermal head as recording debris. The amount of this waste increases as the level difference increases. Therefore, thermal heads that use thick film-like conductors as individual conductors and thin film-like insulators as the retention layer have a lot of recording debris, resulting in poor print recording quality◇ The purpose of the present invention is to The object of the present invention is to provide a thermal head which eliminates the above-mentioned drawbacks, and which has a thin film-like resistive protective layer that makes the printed recording density uniform and has good adhesion to the heating resistor or conductor, and which also has the advantage of making the printed recording uniform. It is an object of the present invention to provide a compact and inexpensive thermal head with less recording debris adhering to the thermal head.

In the thermal head of the present invention, most of the individual semiconductors including the IC mounting part (and the common electrode, if desired) are made of thick film metal in the wiring conductor, which should be substantially a single conductor, and the heating resistor is made of thick film metal. The individual conductors and the rectangular conductors that are connected to the body are made of thin film metal, and therefore the thick film metal and the thin film metal are laminated and connected at arbitrary positions. 0 The following description will be made with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention.

A gold thick film conductor with a thickness of about 5 μm is printed on a substrate 11 made of alumina or alumina that is entirely or partially glazed, and the conductor is fired at a temperature of 800 to 1000° C. to form a thick film metal. In the figure, 12 is, for example, a common conductor,
13 is an individual conductor 0 The thick film metal has high crystallinity because it is fired at a high temperature, and the specific resistance is, for example, 2.5μ.
It has a low value of Ω・C1rL. Next, a thin film resistor 14 made of tantalum/silicon mixture, tantalum nitride, zirconium nitride, chromium/silicon, etc. is deposited on a desired area on the substrate by sputtering or vapor deposition.
Deposit to a thickness of ~0.5 μm. Next, the heating resistor 14
Then, a thin film metal 15 such as aluminum is sputtered in a shape that covers the thick film metals 12 and 13.

It is made to adhere to a thickness of 0.5 to 1 μm on a substrate by a vapor deposition method or the like. Here, for example, 15a is a rectangular conductor, and 15b is an individual conductor. Since aluminum is generally deposited at a low temperature of 400° C. or lower, its specific resistance exhibits a high value of 3 μΩ·α or more, and since the film is thin, its sheet resistance value exhibits a high value. These thick film metals, thin film resistors, and thin film metals are formed into arbitrary shapes by photolithography or heat treated, if desired. Further, the heating resistor 14 is covered and protected by a laminated insulating film 16 of silicon dioxide and tantalum pentoxide having a thickness of 3 to 10 μm, for example, for the purpose of mechanical protection. The insulating film 16 is deposited by sputtering.

In this way, the present invention makes the individual conductor, which should be substantially single, a thin film metal in the part connected to the heating resistor, and a buried metal film with small area and resistance in other parts. This is a thermal head that uses a thin film resistor with excellent thermal response characteristics and a thin protective film, and the manufactured thermal head is small.
Uniform printing density can be provided, and because the difference in level between the resistor and the conductor is small, there is little paper waste associated with recording. In addition, in the thermal head manufactured by this method, the process of attaching the heat generating resistor film and the process of attaching the thin film metal are separated, so the heat generating resistor film is heated at a high temperature of about 600°C. The stability of the resistor formed from the resistor film can be improved by heat treatment.

FIG. 2 is a diagram showing another embodiment of the present invention.

In the figure, thick film metals 22 and 23 . .

The desired shape is glued to the fist and formed. Next, the thin film resistor 24
and thin film metal 25 are successively deposited on desired areas on the substrate by sputtering, vapor deposition, or the like. Thereafter, the thin metal film and the heating resistor film are sequentially formed by photolithography, and an insulating film 26 is further formed on the substrate.
In a thermal head having a zero-wire structure, one heating resistor film and a thin metal film are successively deposited, so the manufacturing process is short and inexpensive. Furthermore, since the thick film metal and the heat generating resistor can form a compound such as a silicon compound or a tantalum compound, the heat generating resistor film is in close contact with the thick film metal region. As a matter of course, it is possible to exhibit the effects described in the first embodiment.0 Figure 3 is a modification of the embodiment shown in Figure 2, in which thick film gold &3
2 and 33, an insulator 37.37' such as tantalum pentoxide or silicon dioxide is deposited at 0.05 to 0.05.
Next, a thin film resistor 34, 34' and a thin film metal 35, 35' were deposited on the substrate to a thickness of 2 μm, and a retentive film 36 was further deposited. A thin resistor film 34.3 deposited on the insulator 37.37' by sputtering or high temperature vapor deposition.
4' is, for example, as stated in Japanese Patent Application No. 47-130072,
The insulators 37 and 37' are randomly penetrated at a large number of positions to have a large number of electrical connection points with the thick film metal, and are in close contact with the thick film metal. The thermal head with this configuration prevents excessive alloy formation between the thick film metal and the thin film resistor.
The thin film resistor film 34, 34' can be prevented by
can be heat treated even at high temperatures. The metal thin film 35' can also be used as a conductor for external terminals.

As described above, the thermal head of the present invention is capable of attaching thin film material only to the desired area, resulting in high productivity and can exhibit the above-mentioned effects. 1 Resolution of heating resistor, number of image signal terminals to be input, number of heating resistors that can be driven by a single IC.

There are no particular limitations on the method of mounting and connecting ICs, etc., and the thermal head of the present invention can be applied to line printers, serial heads, etc. In addition, in order to prevent migration of thick film metal, Furthermore, thick film metal conductors can also be bonded with insulating materials. It is of course possible to provide a conductor resistance correction area for each individual conductor within an allowable area, and the back surface of the substrate can also be used as a common conductor or a ground conductor. It goes without saying that materials, manufacturing methods, film thicknesses, etc., should not be limited in the T and C portions of the present invention. Therefore, magnetron suba is the best method for attaching thin films.

◎The present invention also provides a non-oxidizing thin insulating film. It can also be carried out by depositing an oxidizable thin film metal on top.

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views of the thermal head of the present invention. 11.21, 31: Substrate, 12.22.31 (For common electrode) Thick film metal, 13, 23, 33: (For individual conductor) Thick film metal, 14, 24, 34, 34': Thin film resistor , 15
a, 15b, 25, 35: thin film metal, 16, 26°3
6: Insulating layer% 37.37': Insulating layer.

Claims (4)

[Claims] (1) A substantially single unit formed by branching into a rectangular shape from a common electrode, connected to one end of a thin film heating resistor, and extending from the other end of the resistor to a connection terminal to an IC. In the thermal head, the individual conductors in the region connected to the heating resistor are formed of a thin film metal whose surface layer is oxidizable, and the other regions are formed of a thick film metal. 1. A thermal head characterized in that the thin film metal and the resistor are protected by a thin insulating film. (2) In the thermal head according to claim (1), the thin film metal is directly laminated on the thick film metal,
A thermal head characterized by electrically connecting thick film metal and thin film metal. (3) The thermal head according to claim (1), characterized in that the thin film metal is electrically connected to the thick film metal via a heating resistor attached to the thick film metal. thermal head. (4) In the thermal head according to claim (1), the thin film metal is electrically connected to the thick film metal via an insulating layer (and heating resistor) deposited on the thick film metal. A thermal head characterized by: