JPS6292864A - Manufacture of thick-film type thermal head - Google Patents

Abstract

PURPOSE:To maintain stable printing characteristics for a long period of time, by providing a thick-film resistor pattern constituting heating resistor elements by printing and firing, and thereafter applying electric power higher than that for printing to the thick-film resistor. CONSTITUTION:A glass substrate 1 is prepared (N1), then a gold thick-film layer is provided thereon by screen printing and firing (900 deg.C) (N2), and lead electrodes A1-An are patterned by photolitho-etching (N3). Next, a linear thick- film resistor R is provided by screen printing and firing (870 deg.C) while using a resistor paste comprising ruthenium oxide and a glass as main constituents (N4). Further, electric power higher than that for printing is applied to the thick-film resistor (N5). The resistor in this thick-film type thermal head shows an extremely stable resistance value under printing operations for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a thick film thermal head, and particularly to a method for stabilizing the resistance value of a heat generating resistor element.

[Prior art and its problems]

In the heat-sensitive recording head (thermal head) used in the recording section of a printer or a printing device, as the recording accuracy becomes more mature, the resistance value of each heating resistor becomes uniform, and the resistance value increases over a length of +11]. Stabilizing the resistance value has become a serious problem.

In particular, a thick film type thermal head in which peripheral circuits including a resistor layer are formed by baking a pattern created by screen printing the thick film base 1 is easy to manufacture and inexpensive. Although it has become the mainstream of thermal heads because of its low heat and high mechanical strength,
On the other hand, compared to the 7a film type, the pattern accuracy is poor, the resistance value tends to fluctuate, and the resistance value easily deteriorates at an early stage.

By the way, this thick-film type nursing head generally has a fourth
It is manufactured according to the flowchart shown in the figure.

That is, first, a glazed ceramic substrate insulating substrate is used as a starting material (F1), a conductor is printed by a screen printing method, and then fired (F2), and an electrode is formed by patterning the conductor by a photolithographic etching method. (F3).

Thereafter, a resistor layer pattern for configuring the heating resistor element is formed by screen printing and baking (F
4).

Finally, a wear-resistant layer is printed and fired (F5) to complete the process.

The resistance value of each heating resistor element of the thermal head after completion is
It is determined by the sheet resistance value of the resistor paste used, the pattern dimensions of the resistor pattern, and the firing temperature.

However, the thick-film thermal head formed in this way selectively applies electric pulses of a certain magnitude (power value) to the heating resistor made of thick-film resistors according to image information. It is designed to generate heat to a desired temperature. This thick film resistor generally has a property that its resistance value changes depending on the applied power. Therefore, the resistance value changes during use, and the amount of heat generated changes, causing problems such as changes in print density. For this reason, in the past, it was possible to use only a relatively small amount of power so that the change in resistance value was small, and when used with a large amount of power, there was a disadvantage that the change in resistance value was large and the lifespan was extremely short.

Further, although it is often driven with a constant voltage, in this case, the voltage is fixed to match the initial resistance value, so the resistance value decreases as power continues to be applied. For this reason, the actual applied power increases, accelerating the change in resistance value, and in some cases leading to destruction.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a thick-film thermal head that can maintain stable printing characteristics over a long period of time even when used with high power.

(Means for Solving the Problems) Therefore, in the present invention, after forming a thick film resistor by printing and firing and forming a heating resistor element, before use, a power higher than the printing power is applied to the thick film resistor. We are introducing a process to stabilize the membrane resistor.

(Function) Normally, when the applied voltage to a thick film resistor is increased as shown in curve 1 in Fig. 3, the resistance value of the thick film resistor itself changes when the voltage exceeds a predetermined value. Sisters,
Furthermore, it is known that increasing the voltage causes destruction.

As a result of further various experiments, the present inventors found that when a voltage higher than a predetermined voltage is applied to a thick film resistor, the resistance value changes, but after that, when a voltage lower than the voltage is applied. It was also found that there was almost no change in resistance value.

The present invention has been made with this in mind. Prior to use, a resistance value is caused to change by applying power greater than the working voltage in advance, and when power is applied during use, the resistance value The aim is to ensure that no changes occur.

That is, the power Δ' corresponding to the minimum point A of curve 1 in FIG.
After applying the following power value, for example, power B', to the thick film resistor in advance, applying power again and measuring the characteristics again, as shown in curve 2, the applied power below power B' On the other hand, the change in resistance value is so small that it can be almost ignored.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Figures 1 and 2 (a). (b) is a flow diagram showing the manufacturing process of a 6-dot/InIn thick model thermal head according to an embodiment of the present invention, and a partial schematic diagram of the same thick film type thermal head. (Figure 2 (b) is shown in Figure 2 (
It is an AA' sectional view of a). ) This thick film type thermal head has a width W on a glass substrate 1.
1 = 25 μm thick gold film pattern with mutual spacing d =
Lead electrodes A1 arranged in a staggered manner at 167 μm
...80, and the width W2 provided on this upper layer = 200μ
A linear thick film resistor R whose main component is 7W (7) M-ruthenium chloride is formed, and current is supplied to each lead electrode according to image information, and the thick film resistor Body R
A predetermined element region of the device is selectively made to generate heat.

Next, a method for manufacturing this thick film type one-terminal head will be explained.

First, a glass root 1 is prepared.N1) A thick gold film layer is formed on this surface by screen printing and baking (900°C) (N2), and then lead electrodes 1... Perform buttering (N3)
).

This is followed by screen printing and firing (870
°C) to form a linear thick film resistor R (N4)
.

The relationship curve of the rate of change in resistance with respect to the application of electric power to the thick film resistor thus formed was as shown in curve 1 in FIG. 3. A power B' which is smaller than the applied power A' when the resistance change rate takes the minimum point A and which is larger than the printing power is applied to the thick film resistor R (N5
). (At this time, the pulse width is 100 to 10 of the printing pulse width.
It is assumed to be about 1/00. ) The relationship curve of the resistance change rate with respect to the power application of the thick film resistor R after power is applied is as shown in curve 2 in Figure 3, and at a power below the power B', the change in resistance value is almost negligible. Met.

In this way, this thick-film thermal head maintains an extremely stable resistance value even during long printing operations, making it highly reliable.

In the example, a thick gold film was used for the lead electrode, and a material mainly composed of ruthenium oxide and glass was used as the resistor layer, but this is not necessarily limited to these, and other materials may be used. Needless to say, this method is also effective when using a thick film material.

The method of the present invention can also be applied to the case where a protective layer such as a wear-resistant layer is formed on top of a thick film resistor, and in this case, stabilization by applying power is performed after forming all layers. Alternatively, it may be carried out prior to the formation of the 1ffl.

〔effect〕

As described above, according to the present invention, when producing a thick-film thermal head that is formed from a large number of lead electrodes and thick-film resistors and constitutes a plurality of heat-generating resistor element regions, printing is possible. After forming heat generating resistor element regions by firing and baking, for the thick film resistor pattern in each element region,
Since the resistance value is stabilized by applying a power larger than the printing power, the resistance value of each element area is stable over a long period of time, and it is extremely easy to achieve long life and high reliability. It becomes possible to form a thick film type thermal head.

[Brief explanation of drawings]

Figure 1 J5 and Figures 2 (a) and (b) are flow diagrams showing the manufacturing process 1 of the thick film type thermal head according to the embodiment of the present invention, and parts of the same thick film type thermal head, respectively. The schematic diagram, Figure 3, shows the relationship between the applied power and the rate of change in resistance when an electric pulse is applied to the heating resistor.
FIG. 4, which is a comparison diagram of the one formed by the method of the embodiment of the present invention and the conventional one, is a flowchart showing the manufacturing process of a conventional thick film type thermal head. <A)-A, A, Am+2 ・(A
, )...1 m m÷1 Lead electrode, R... Thick film resistor, 1... τ formed by the usual method l [Power and resistance change when power is applied to the heating resistor 2. Curve showing the relationship between electric power and resistance change rate when electric power is applied to the heating resistor formed by the method of the present invention. Figure 1 Figure 2 (σ) Figure 2 (b) Figure 4

Claims (2)

[Claims] (1) In a method for manufacturing a thick-film thermal head in which a heat-generating resistor element consisting of one or more thick-film resistors is arranged on an insulating substrate, the thick-film resistor constitutes the heat-generating resistor element by printing and firing. A method for manufacturing a thick-film thermal head, comprising: after forming a pattern, a resistance stabilization step of applying power greater than printing power during use. (2) The electric power applied in the resistance stabilization step is in the form of an electric pulse having a pulse width of about 1/100 to 1/1000 of the printing pulse. ) The method for manufacturing a thick-film thermal head described in item 2.