JPS62128101A - Thermal head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal head used for thermal print recording.

[Technical background of the invention and its problems] As shown in Figure 1, the purchase of a thermal head consists of a plurality of resistive films on a ceramic substrate (1) treated with a glass glaze, and power is supplied to the heat-generating resistive film. Electrical conductor for (
3), and according to the information to be recorded, a current is passed through the corresponding heating resistive film through an electric conductor to generate heat so as to obtain the necessary thermal pattern, and recording is performed by contacting the recording medium. It is. Conventionally, the heating resistive film was made of Ta.
There is a TTa-8in resistive film obtained by sputtering a target obtained by sintering and StO powder. (For example, W
, Kaisho However, this heat-generating resistive film has large variations in resistance, which often results in uneven printing.

The cause of this resistance value abnormality was not clear, although it was a major factor in reducing product yield.

[Purpose of the invention]

This invention was made in consideration of the above points.

It is an object of the present invention to provide a thermal head with little variation in resistance value of a heat generating resistive film.

[Summary of the invention]

The present invention has discovered from the results of structural analysis of various heat generating resistive films of thermal heads that the variation in the resistance value of the heat generating resistive film depends on the cristobalite content contained in the heat generating resistive film. The amount of cristobalite is S
This thermal head is characterized by using a heat-generating resistive film having an amount of tO of 20 wt% or less.

Structural analysis of the heating resistive film was performed using X-ray diffraction, a transmission electron microscope, a differential scanning calorimeter, and the like.

It is clear from the results of X-ray diffraction and the like that the heat generating resistive film is an amorphous film. In addition, thermal behavior analysis of the film using a differential scanning calorimeter revealed a crystal phase transition in areas with a specifically high resistance value, and this phase transition occurs because the phase transition temperature is the same as that of the cristobalite constituent phase of the target. , it was concluded that this was a phase transition of cristobalite. The amount of cristobalite was determined from the ratio of the phase heat transfer of the film obtained using a differential scanning calorimeter to the cristobalite phase transition heat O031Keal/mol (quoted from a chemical handbook). As a result, the amount of cristobalite is more than 20wt% of the total amount of sio in the part with a specific high resistance value, whereas in the normal part it is less than 20wt% and the rest is amorphous Sin! and Ta. A similar analysis was conducted for the target used in the heat generating resistive film 1, and as a result, there was a correlation between the amount of cristobalite in the heat generating resistive film and the greased paralyte (Q) in the target. 20wt of cristobalite a in the heating resistance film
In order to make it less than 1, it can be achieved by reducing the amount of cristobalite in the target to less than 20 wt%.

3wt or less is better.

Next, conditions for a method of manufacturing such a resistor and target 8 will be described. The reason why the sintering temperature was set to 1200 to 1450° C. is because cristobalite increases at a temperature higher than this, and the density of the sintered body does not become sufficiently high at a temperature lower than this. The temperature is preferably 1250 to 1350°C.

Further, the reason why the substrate heating temperature during sputtering is set to 90° C. or higher is because cristobalite is easily formed at a temperature lower than this. However, if the amount of cristobalite in the sintered body is small, a resistive film with sufficient variation can be obtained even if the substrate heating temperature is 90°C or less, and even if the amount of cristobalite in the target is large, the substrate heating temperature during sputtering is 90°C or higher. If it is high, a resistor with little variation can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a heat generating resistive film with little variation in resistance value is used, so a thermal head without uneven printing can be obtained.

[Embodiments of the invention]

The implementation sequence of the present invention will be explained below.

(Implementation girUl) Ta powder adjusted to an average particle size of 3 μm and 100 μm in advance
A powder of SIO, whose water of crystallization was removed by heat treatment at 0°C, was prepared, and Ti:8i0. The mixture was mixed in a ball mill at a ratio of 7:1. Thereafter, the mixed powder was burned by hot pressing using a carbon die. The sintering temperature at this time was 1200°C. A part of the sintered body was scraped off and the constituent phases were investigated by X-ray diffraction. As a result, Si, Tag, β-Ta
The presence of tO, Ta, Ta, and Si was observed, but cristobalite-type Sin.

was almost non-existent using this X-ray diffraction method.

Thereafter, using a target having this structure, a heating resistor (3) was formed by sputtering on an AI, O8 substrate (1) which had been coated with a brace (2) in advance.

Sputtering was performed in Ar gas at 10"-" Torr. Further, the substrate heating temperature at this time was 130°C. After that, Cu, Pd, Au, and Cr are deposited as electrodes (4), and a predetermined pattern is formed by etching, and then a protective film (5) is formed at step S10. and T a, o, were formed on a resistive film by sputtering, and wiring was made to drive the resistor to complete the thermal head.

For comparison, a similar thermal head was made in which the target sintering temperature was 1700°C and the substrate heating temperature during sputtering was 70°C.

When we examined the resistance films of these two thermal heads, we found that the inventive product had a variation of ±10 when the reference resistance value was 100, but the comparison product had a variation of ±120, which caused unevenness during printing. It happened a lot.・Next, the cristobalai (SiO) in the resistive film and the target
The amount of l was determined by analysis.

First, differential scanning thermal bone measurement (DSC) of the heating resistive film was performed. At this time, the content of cristobalite contained in the heating resistive film is the phase transition heat obtained from the DEC data and the phase transition heat of cristobalite, which is 0.31 Kcal/mol (
(quoted from Higaku Iran). On the other hand, the content of cristobalite contained in the target was also determined by the above method. As a result, as shown in Table 1, the M content of cristobalite in the heating resistive film is desirably 3 wt % or less with respect to 5 int of the amorphous material.

(Examples 2 to 5) The following four types were produced in the same manner as in Example 1.

Conditions different from Example 1 are as follows.

' 3: ' 1300℃ 20
0℃14: -1350℃ 150℃-
5: #1250℃ 100℃This thermal head was analyzed in the same manner as in Example 1. As shown in Table 1, cristobalite StO! i was small, and the variation in resistance value was also small.

Here, the amount of cristobalite in the target is - 8i0 added before tying! The cristobalite in the resistor is the total Sin in the resistive film in terms of weight to weight ratio, and the variation represents the difference in index when the target resistance value is set to 100.

The present invention is applicable not only to the targets of Akioki but also to Ta and SiO.
It can also be applied to targets as complexes that combine the two. Further, Ta can be replaced with other elements having a high resistance value, such as Mu, N1-Cr, etc., and this is effective for a composite system of high resistance elements -8i0°.

[Brief explanation of drawings] FIG. 1 is a sectional view of the main parts of the thermal head. 3... Heat generating resistor. Agent: Patent Attorney Noriyuki Chika Same Bamboo Flower Kikuo

Claims (5)

[Claims] (1) In a thermal head having a substrate and a heat generating resistive film formed on the substrate, the resistive film is made of Ta and SiO_
2 as the main component, and the content of crystalline SiO_2 is SiO_
A thermal head characterized in that the amount of the thermal head is 20 wt% or less based on the total amount of the above. (2) The thermal head according to claim E1, wherein the main component of the crystalline SiO_2 is cristobalite. (3) The heating resistive film has an abundance ratio of cristobalite of S
2. The thermal head according to claim 1, wherein the thermal head is a sputtered film using a target with an amount of iO_2 added of 20 wt% or less. (4) The temperature of the resistive film-attached substrate during sputtering is 90°C.
Claim 3, characterized by being able to stand above ℃
Thermal head described in section. (5) The thermal head according to claim 3, wherein the target is sintered at a temperature in the range of 1200 to 1450°C.