JPS62119059A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head of low cost, high accuracy, and small size, by a method wherein a thick film conductor is disposed under a plurality of common electrodes as a connecting electrode connecting the common electrodes of opposite side to those connected to an integrated circuit for driving heating resistors, and the connecting electrode and the common electrodes are connected to each other through openings formed in an insulator. CONSTITUTION:After a high-temperature insulating glazed layer 2 is formed using an insulating substrate 1 of alumina, common electrodes 3 of negative side, common electrodes 4 of positive side, ad required crossunder electrodes are formed out of a thick film conductor of copper. Thereafter, a crystalline glass layer 6 provided with through-holes 5 is formed, and a non-crystalline glass layer 7 is formed in order to enhance a surface smoothness and properties of forming an upper thin film pattern. After the substrate is cleaned, a thin film conductor 8 is formed by depositing Ta2N/ NiCr/Au/Cr in this order all over the substrate. After the thin film conductor 8 is patterned, a protective layer 9 consisting of SiO2/Ta2O5.SiO2 is formed thereon. After a protective resin 10 is formed by printing, the Cr in a bonding pad portion is removed by etching and Au-plating is applied thereon. Thereafter, a drive IC 11 is installed and wire-bonded, and a semiconductor protective layer 13 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary of the Invention] The present invention provides a high-density thermal head, particularly of the center type, which uses a thick film conductor under a glass insulator as a large common electrode connecting each small common electrode.

[Industrial application field]

The present invention relates to a thermal head, and particularly to a driver IC-mounted thermal head using multilayer wiring in which a thick film conductor and a thin film resistor are formed on the same substrate.

[Conventional technology and problems]

The thermal head, which is the recording section of a thermal printer, consists of a heating resistor, a lead wire, and a substrate.

A driver IC-mounted thermal head equipped with a driver IC has the effect of including part of the multilayer wiring inside the IC, so that a high-density head can be realized relatively easily.

Conventionally, in such a varibar IC mounted type smartphone, a driver IC is arranged so as to face a row of heating resistors, as shown in FIG. This kind of arrangement is suitable for a thermal head with a bit count of about 10/mm.
It can be easily applied to arrays and pattern wiring, etc. However, when the number of bits exceeds 10/mm, it is common to place ICs on both sides of the heating resistor array.

In this case, the small common electrodes of the heating resistors are formed successively for each number of bits of the IC to be connected. Further, the common electrodes of each IC must also be connected to each other. This I
As shown in the figure, it is not easy to connect the common electrodes of C to each other because there is an adjacent heating resistor connection electrode, but conventionally an insulated wire is used to cross over the adjacent heating resistor (lead wire) row. In the case of a thin-film thermal head, an insulating resin layer made of polyimide or the like is formed with through holes on the heating resistor array, and a thin film that becomes the common electrode of the IC is formed on top of the insulating resin layer. I was doing things like that.

When the heating resistor array is crossed over by soldering the insulated wire, the workability is poor, and the soldering poses problems such as contamination of the bonding pads by flux and the like. On the other hand, when forming a thin film for a common electrode by forming a resin layer such as polyimide, there is a problem that the thin film forming process increases by one step, resulting in high cost.

An object of the present invention is to provide a high-density thermal head that solves the above problems.

[Means for solving problems]

According to the present invention, the above problem is solved in a thermal head in which a heat generating resistor array is arranged on a substrate via an insulator, and resistor driving integrated circuits are mounted on both sides of the heat generating resistor array. A thick film conductor is disposed below the plurality of common electrodes as a connection electrode for connecting the plurality of common electrodes on the side opposite to the side connected to the integrated circuit for driving the heating resistor, and the connection electrode and the plurality of common electrodes are connected to each other. The thermal head is connected to the common electrode through an opening formed in the insulator.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a plan view for explaining one embodiment of the present invention, and FIG. 2 is a plan view of the section AA' in FIG.

Using an insulating substrate 1 made of alumina with a purity of 97%, a high-temperature insulating glaze layer (glass layer) with a softening temperature of 750°C or higher
After forming the common electrode 2, a common electrode 4 on one side of the common electrode 3+ and a necessary cross-under electrode (not shown) are formed using a thick film conductor made of copper.

Next, a crystalline glass layer 6 provided with through holes 5 is formed.

Next, amorphous glass N7 was formed to improve surface smoothness and formability of an upper thin film pattern. After cleaning the substrate, a thin film conductor 8 of TaJ/NiCr/Au is applied to the entire surface of the substrate.
/Cr respectively 300 people/300 people 15000
It was formed by vapor deposition to a thickness of 300 people/300 people. Next, after forming each pattern on the thin film conductor 8 by photolithography, Si
R the protective film 9 consisting of ng/Tag's 5iOz
It was formed by F sputtering method.

After printing and forming the protective resin 10, Cr on the bonding pad portion was removed by etching, and Au plating was applied.

Next, the drive ICII is mounted and wire bonded,
After forming the semiconductor protection resin 13, the central resistor type 16
A thermal hefed board equipped with a book/mm IC has been completed. 2
2 is a heating resistor.

The crystalline and amorphous thick film glass insulators shown in FIG. 2 may be formed on the entire surface other than the insulating glaze.

FIG. 3 shows an example in which two layers, a crystalline glass layer 6 and an amorphous glass layer 7, are formed on the entire surface other than the heat insulating glaze part, and FIG. 4 shows an example in which the amorphous glass layer 7 is formed in the heat insulating glaze part. This is an example in which it is formed on the entire surface other than the

In this way, a glass layer is formed even in areas that are unnecessary for the function of an insulator, improving the surface roughness of the lower alumina insulating substrate 1 and contributing to improved pattern formability.

Furthermore, the lower thick film conductor is not limited to copper, and conductors whose main components are gold, silver, baradium, platinum, etc. can be used.

Furthermore, the upper resistor and conductor thin film are made of TatN/NiC
Not limited to r/Au/Cr, resistors such as Ta-81, Ta-5t, and AA! , Cu, Cr, W, Mo, or the like can be used as a single layer or a multilayer film.

Further, when copper is used for the thick film conductor, the copper surface may be plated with Ni or the like before forming the thin film to protect the exposed portion.

Furthermore, in the present invention, forming the common electrode 4 between the insulating substrate 1 and the glaze layer 2, for example, as shown in FIGS. 4A and 4B, reduces the resistance value of the common electrode and makes the thermal head more compact. The above is also preferred. 30 is adhesive glass.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain an inexpensive, high-density, and compact thermal head.

[Brief explanation of drawings]

FIG. 1A is a plan view for explaining one embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA' in FIG.
2 and 3 are cross-sectional views showing a method of forming a glass layer on a substrate, and FIGS. 4A and 4B show a thick film conductor disposed between a substrate and an insulating glaze layer. FIG. 5 is a plan view for explaining a conventional example. 1... Insulating substrate, 2... Heat insulating glaze layer,
3... - side common electrode (thick film conductor), 4... + side common electrode (thick film conductor), 5... through hole, 6... crystalline glass layer,
7... Amorphous glass layer, 8... Thin film conductor, 9...
Protective film, 10... Protective resin, 11... Drive IC113... Semiconductor protective resin, 30... Adhesive glass. Ro 3 @ Conventional example 5 @

Claims (1)

[Claims] 1. A thermal head in which a row of heat generating resistors is disposed on a substrate with an insulator interposed therebetween, and integrated circuits for driving the resistors are mounted on both sides of the row of heat generating resistors. A thick film conductor is disposed below the plurality of common electrodes as a connection electrode for connecting the plurality of common electrodes on the opposite side to the side connected to the integrated circuit for driving the resistor, and a thick film conductor is disposed under the plurality of common electrodes, and A thermal head characterized in that the electrode is connected to the electrode through an opening formed in the insulator. 2. The thermal head according to claim 1, wherein the thick film conductor is selected from the group of copper, gold, silver, palladium, and platinum. 3. The thermal head according to claim 1, wherein the thick film conductor is disposed between the substrate and the insulator. 4. The thermal head according to claim 1, wherein the insulator is crystalline glass. 5. The thermal head according to claim 1, wherein the insulator comprises two layers of crystalline glass and amorphous glass.