JPH01105757A - Thermal head - Google Patents

Abstract

PURPOSE:To improve printing performance and reduce the size and cost by producing an iron alloy of a specific quantity of Cr as a base and the specific content of at least either one selected of Al, Si, Sc, Ti, V, Y, Zr, Nb, La and Hf. CONSTITUTION:A thermal head 1 consists of a driver substrate 3 and a resistor substrate 4 mounted and fixed on an aluminum radiation substrate 2. A drive IC 5 is mounted on the drive substrate 3 and a discrete lead 8 and a thermal resistor 10 are mounted on the resistor substrate 4. A high resistance base 11 of the resistor substrate 4 is composed of a metallic substrate 12 made or an iron alloy containing 5-30wt.% of Cr and 0.05-5wt.% of at least either one selected of Al, Si, Sc, Ti, V, Y, Zr, Nb, La and Hf and a high resistor layer 13 of a glass layer. Addition of Al, etc. contributes to the improvement of adhesion of the metallic substrate and the glass layer, and also to their corrosion inhibition. The above-mentioned constitution reduces the size and cost as well as improves printing performance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Industrial Application Field) The present invention relates to a thermal head, and particularly to a substrate thereof.

(Prior art) In recent years, thermal heads have been used in facsimiles, printers,
It is used in recording devices such as word processors, and has a wide range of uses.

Generally, in thermal heads, Al1 is used as a high resistance substrate.
Ceramic substrates with a purity of 20s of 90% or more are often used. However, when forming this ceramic substrate, a process of removing alkali metal components from the raw material powder,
Since high-temperature firing and finishing steps such as polishing to remove undulations and the like of the substrate generated during the high-temperature firing are required, an increase in cost is unavoidable. Further, the thermal head performs recording on thermal paper or the like by passing a current through a heating resistor provided between an individual electrode and a common electrode, heating the heating resistor by Joule heating, and generating heat. By the way, in a thermal head using a ceramic substrate as described above, since the entire substrate has a high resistance, it is necessary to form a common electrode individually on the surface of the substrate.

These go against the current trend in the industry, which is searching for smaller and lower cost thermal heads.

(Problems to be solved by the invention) The present invention has been made in view of the above-mentioned problems,
The purpose is to provide a small, low-cost thermal head with excellent printing performance.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the thermal head of the present invention includes a high-resistance substrate containing Qr of substantially 5% to 30% by weight, ACSi, sc, Ti.

It is made of an iron-based alloy containing substantially 0.05% to 5% by weight of at least one selected from the group of V, Y, Zr, Nb, 1-a, and 1-1f.

The actual PM mode is characterized in that a high-resistance layer made of glass or heat-resistant resin is disposed.

(Function) Since the thermal head of the present invention does not use a ceramic substrate, firstly, the substrate can be used as a common electrode, and secondly, the step of removing alkali metal and the step of removing waviness during the formation of the ceramic substrate can be avoided. It has the effect of making it unnecessary.

Roughly speaking, in an embodiment of the thermal head of the present invention, the first
Second, by appropriately selecting the additive elements of the base material, the adhesion between the base material and the high-resistance layer provided on the base material can be improved, and secondly, by using heat-resistant resin for the high-resistance layer, bending is possible. becomes.

(Embodiment) An embodiment of the thermal head of the present invention will be described below as shown in Fig. 1 (2).
) and FIG. 10, and FIG. 1(
2) is a schematic diagram of a flat thermal head, and FIG. 1 υ is a simplified sectional view of the main part of FIG. 1 (4).

In FIG. 1 (4), the thermal head ω includes a driver board (3) and a resistor board (4) placed and fixed on a heat dissipating board (7) made of aluminum via an adhesive member (not shown). There is.

A driving 7C5) is placed on the driver board (2), and a conductor wiring (2) for inputting a signal current, etc. to the driving IC (2) is electrically connected via a bonding wire (2).

On the other hand, on the resistance substrate (a), individual leads (8) are electrically connected to the driving IC (2) via bonding wires (9). A heating resistor q0 is electrically connected to the tip of this individual lead (8), and the other end of this heating resistor 0Φ is electrically connected to the resistance board (4).

Note that (c) is a protective layer that protects the heating resistor QO.

Next, the resistor substrate (a) will be explained in detail with reference to FIG. 1 υ. In FIG. 1(c), the high resistance substrate 00 is made of Fe.
- 1511% 0r - 4% by weight i - 0,2% by weight T
A metal substrate 0 with a thickness of 0.75 # consisting of i, PbO161ff1%, Si formed on this metal substrate ■
O2513 weight 1%, An 20s 91p%, 820
34% by weight, C(10) 3% by weight, others Bad, Cr
z03. High-resistance layer C made of a glass layer containing NfO
It is formed from force. In order to improve the adhesion between the metal substrate 0 and the high-resistance layer 03), gold a is added to the interface between the metal substrate 0 and the high-resistance layer 03) before forming the high-resistance layer C[F]. The oxide (b) consisting of the constituent components of the substrate (2) is a dense oxide consisting of AJ2203°AJ2TizO5 in the case of this embodiment. In this way, the presence of an oxide layer on the surface of the caulked metal substrate improves its adhesion to the glass.The reason why the surface oxide on the surface of the metal substrate flows from the surface into the glass when it comes into contact with high-temperature glass during the formation of the glass layer. This is because the glass melts into the oxide and an intermediate temperature where the two are mixed is generated.

Elements that are easily distributed between these two groups are Al, Si, and Ti.

Zr etc. In addition, as a result of various experiments, in many cases, if a spinel type oxide layer is formed on a metal substrate and a reaction layer is created between it and the glass layer, the adhesion becomes extremely good. In other words, in the case of a metal substrate mainly composed of Fe and Qr, the temperature is 1150 to 1250°C in wet hydrogen with a dew point of 25 to 30'C.
The surface is oxidized for 30 minutes to 1 hour, and AuO3, S[)z, T! When an oxide layer containing an oxide such as 02 or the like, which has a spinel type crystal structure, is formed, the adhesion with the glass layer becomes extremely good. Of course, this is not the case if adhesion is ensured.

The thermal head in one embodiment has a structure in which the metal substrate (support) also serves as a common electrode.

For this purpose, after forming the oxide layer (b) on the metal substrate 0, the -part oxide layer [Co., Ltd.] was removed, and then screen printing, drying, and firing were performed to form a glass layer of 80 pJn.

At this time, a heating resistor 0Φ made of Ta-5r-o system was formed on this high-resistance substrate aD by a sputtering method, a hole was opened in a part of this heating resistor QO, and a heating part OΦ was formed there. An individual electrode (2) consisting of eight ρ is formed so as to cover at least this heat generating portion OΦ, and S! 02
A protective film for preventing oxidation consisting of a
A wear-resistant film (a) consisting of 205 was formed by a sputtering method.

Next, other embodiments of the present invention will be described with reference to FIGS. 2(4) and 2(g). FIG. 2 (2) is a schematic diagram of a vertical thermal head, and FIG. 2 υ is a simplified sectional view of the main part of FIG. 1 (4). In addition, in Figure 2 (4), the first
Detailed explanations of the same parts and parts as in FIG. 2 will be omitted.

In FIG. 2 0, the high resistance substrate 00 is composed of Fe-18% by weight, Cr-0, 4% by weight Tt-0, 2% by weight 1-0.
．． It is constructed by forming a polyimide layer with a thickness of 30p on a metal substrate with a thickness of 0.1# made of 3i with a double weight ratio.

In this case, unlike in one embodiment, no oxide layer is formed.

This is because when polyimide is used for the high-resistance layer, oxidizing gas generated during curing oxidizes the surface of the metal substrate, thereby promoting adhesion between the polyimide and the metal substrate.

Therefore, in other embodiments, it is desirable to perform heat treatment in a dry hydrogen atmosphere before coating the polyimide to reduce the oxide layer produced during the production of the metal substrate.

The thermal head in other embodiments also has a structure in which the metal substrate 0 also serves as a common electrode by screen printing a prepolymer solution and performing precure-one curing to form a 30-cape polyimide I! (33) was formed. After this,
After sputter etching the polyimide surface in Ar+02, a heating resistor 00 made of Ta-3i-0 series
is formed by sputtering method, and this heating resistor αΦ
Open a hole in the upper part and form the heat generating part 0 here A
An individual electrode (8) consisting of l1 is formed to cover at least this heat generating part 0Φ! Oxidation-resistant protective film made of Ta205 (to) and wear-resistant film made of Ta205 (a)
was formed by sputtering method. Thereafter, bending was performed to assemble a vertical head as shown in FIG. 2 (4).

In the thermal heads in other embodiments, the metal substrate (1) also serves as the common electrode, so the step of forming the common electrode on the substrate, which was necessary when forming the conventional thermal head, can be omitted. In addition, it is possible to make the substrate thinner, and the combination of the metal substrate 0 and polyimide makes it possible to bend it, making it possible to create a vertical thermal head, which has been sought as a compact thermal head for some time. . As a result, it is possible to obtain a thermal head that is low in cost, small in size, and has excellent printing performance.

In addition, if this polyimide M03) is used, the heating resistor α
It goes without saying that the insulation between Φ and the metal substrate (2) can be achieved in the same manner as in the first embodiment. Also, since the metal board (2) needs to be bent, the thickness of this board is approximately 0.03mm. ~1M
If it is within this range, bending can be done easily.

Next, the inventors of the present invention have previously devised a material for the high-resistance substrate.
``L instead of e-Cr alloy'', Si in e-Cr alloy
, Sc, Ti, V, Y, Zr, Nb.

The reason for using an alloy to which at least one selected from the groups 1-1f is used will be described.

First, when using a thermal head with a glass layer formed on a metal substrate, a high-resistance layer and heat insulating layer must be formed on the surface, but when simply using an Fe-Cr alloy, In many cases, the adhesion between the metal substrate and the high-resistance layer is insufficient. On the other hand, AJ and Si in Fe-Cr alloy.

When Sc, Ti, V, Zr, Nb, La, and Hf are added and an oxide layer containing oxides of these components that easily melt into glass is formed on the surface of the metal substrate, especially a spinel type oxide layer, the metal substrate can be formed. The adhesion between the glass layer and the glass layer is significantly improved.

Second, the metal substrate for the thermal head comes into contact with various corrosive gases for dry etching and etching solutions for chemical etching during the manufacture of the thermal head, and is also used in a high temperature and high humidity environment during actual use. corrosion resistance is required. Fe-0c alloy with AJ, Si, 3c, Ti,
V, Zr.

Nb, La, Hf, especially AJ2. Addition of Tr and Hf further improves corrosion resistance.

Thirdly, the reason why we chose Fe-Cr alloy for the metal substrate is that it is a ferritic stainless steel with a bCC structure.
Thermal expansion coefficient is about 10XIO-6 to -1, which is close to about 7X10-6 to -1 of the conventional thermal head substrate AnzO3 The membrane material can be used as is, and the thermal expansion coefficient of FCC structure austenitic stainless steel is approximately 17X 1.
Although it may be as large as 0-”K″′1, An, Sc,
Ti, V, Zr, Nb.

Addition of La and Hf has the effect of stabilizing the ferrite layer with the bcc structure and suppressing austenitization.

Therefore, in order to take advantage of the characteristics of the Fe-Cr alloy (corrosion resistance that prevents contact with various dry etching gases and chemical etching solutions during the manufacture of thermal heads), it is necessary to It is sufficient to contain % by weight to about 30% by weight, preferably about 8% to about 20% by weight.

Next, Sc, Ti, V, Zr, Nb.

The reason why the addition ports of 1-a and 1-1f were substantially limited to 0.05% by weight to 5% by weight is as follows. If it is less than 0.05% by weight, the above effects cannot be expected. If the amount exceeds 5% by weight, there is a risk that the third element itself may change the crystal structure to an FCC austenitic system, and the workability during thin plate processing will also be significantly degraded, which is not economically advisable.

Note that by selecting the addition port for the third element and roughly selecting the thickness of the oxide layer, this oxide layer can also be used as a high-resistance layer.

〔Effect of the invention〕

By adopting the above configuration, the thermal head of the present invention is small, inexpensive, and has excellent printing performance. Figure 1 (4) is a schematic diagram of a flat thermal head showing an embodiment of the present invention.
FIG. 1 υ is a simplified cross-sectional view of the main part of FIG. 1 (4), FIG. 2 (C) is a schematic diagram of a vertical thermal head showing another embodiment of the present invention, and FIG. It is a simplified cross-sectional view of the main part of FIG. 2(2).

■...Driver board, (4)...Resistance board, ■...
・・Conductor wiring, (8) ・・Individual lead, 00・
...heating resistor, ■...metal substrate, 0...high resistance layer, polyimide layer, C...oxide layer.

Agent: Patent Attorney Noriyuki Chika Same Bamboo Flower Kikuo (a) (b) Ri.

Figure 1

Claims (11)

[Claims] (1) A thermal head comprising at least a base, a heat generating resistor formed on the base, and a conductor formed on the base and electrically connected to the heat generating resistor, the base comprising: Substantially 5% to 30% by weight of Cr, Al, Si, Sc, Ti, V, Y, Zr, Nb, La
, Hf substantially zero.
．． 1. A thermal head characterized by being made of an iron alloy containing 05% to 5% by weight. (2) The thermal head according to claim 1, wherein the base body is made of a metal and an oxide layer of a constituent element formed on the main surface of the metal. (3) The thermal head according to claim 2, wherein the oxide layer is a spinel-based oxide. (4) The thickness of the base is substantially 0.03 mm to 1
Claim 1 characterized in that it is in the range of mm.
Thermal head described in section. (5) The thermal head according to claim 1, wherein a high-resistance layer is interposed between the base, the heating resistor, and the conductor. (6) The thermal head according to claim 5, wherein the high resistance layer is made of a glass layer. (7) The thermal head according to claim 6, wherein the glass layer is made of crystallized glass. (8) The thermal head according to claim 5, wherein the high-resistance layer is made of a heat-resistant resin layer. (9) The high-resistance layer comprises an oxide layer of a constituent element formed on the main surface of the base, and a glass layer formed on the oxide layer. The thermal head according to item 5. (10) The thermal head according to claim 9, wherein the oxide layer is a spinel-based oxide. (11) The thermal head according to claim 9 or 10, wherein the glass layer is made of crystallized glass.