JPH0730464B2 - Method of forming insulating hollow layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an insulating holo layer that can serve the purpose of insulating and wear resistance of a holo substrate, a thermal head substrate, a bearing of a small motor, a sliding portion of a mechanical seal, and the like. Regarding the forming method.

2. Description of the Related Art A so-called holo substrate, which is a glass layer baked on a base material such as stainless steel, aluminum, or a steel plate for holo, has been widely used for household appliances such as cooking appliances and heating appliances. The holo substrate used is used as a bearing for electronic components such as circuit boards and thermal head substrates and small motors because it has excellent heat dissipation and wear resistance.

Next, a method for forming the holo substrate will be described.

The manufacturing process of the holo substrate is shown in FIG. As shown in Fig. 1, a glass frit made by melting and cooling is milled with a ball mill to prepare a slurry for electrodeposition, and a metal substrate such as stainless steel and a steel plate for holo is immersed in this slurry to form a counter electrode. A DC voltage is applied between the metal substrates to electrodeposit glass frit particles on the metal substrates. After electrodeposition, the substrate is thoroughly dried and baked in the baking pattern shown in FIG. 10 to form a holo substrate. The surface roughness of the holo substrate formed by this method is 0.15 μm or more in terms of center line surface roughness Ra,
Moreover, the swell was large and there were many pinholes. In particular, when the conductive circuit of the thermal head is formed on the surface-like hollow substrate as described above, variations in resistance value increase or the circuit is broken, so a satisfactory substrate for the thermal head is obtained. I couldn't do it.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned problems of the surface property of a holo substrate, and more particularly relates to a method for forming a holo substrate having a small surface roughness.

Means the present invention for solving the problem, then coated with _{SiO 2 -B 2 O 3 -MgO-} BaO -based fine powder of crystallized glass on a metal substrate, crystallized from the softening point of the crystallized glass described above Heat treatment at a temperature within the range of
After that, the crystallized glass is further fired at the working temperature to form a holo substrate having a centerline surface roughness Ra of 0.15 μm or less.

Action As described above, by performing heat treatment in the temperature range from the softening point to the crystallization start point of the crystallized glass before firing at the working temperature, the coated glass layer flows and the surface irregularities are leveled. If the glass is heat-treated at a temperature lower than the softening point, the glass does not soften, and thus the surface unevenness is not leveled. In addition, when heat treatment is performed at a temperature equal to or higher than the crystallization start point, the surface is not softened and does not flow, and crystallization begins with unevenness.

As described above, by performing heat treatment in the temperature range from the softening point to the crystallization start point before firing at the working temperature, it is possible to form a holo substrate having excellent surface properties.

Examples (1) Metal Substrate A low carbon steel plate for holo, an aluminized steel, a stainless steel plate, and other similar steel plates can be used as the metal substrate. However, a steel plate having a thermal expansion coefficient of 60 to 140 × 10 ⁻⁷ / ° C. is preferable. In the following examples, a stainless steel plate (SUS430) was used.

(2) Crystallized glass Since crystallized glass must have excellent insulating properties and abrasion resistance, glass that is usually used for holo products cannot be used. Therefore, in the present invention, the second
The glass in the table was used.

(3) Method of Forming Insulating Holo Layer FIG. 2 is a diagram in which the present invention is applied to a substrate for a thermal head, in which an insulating holo layer 2 is provided on both sides of a metal substrate 1. 3 is an electrode, 4 is a heating resistor, and 5 is a wear resistant layer.

FIG. 1 is a process diagram showing a method for forming an insulating holo layer by the electrophoretic electrodeposition method. The glass material is first melted at 1250 to 1350 ° C., and in a roll cooler, cullet of crystallized glass is obtained. This is crushed with a crusher such as a ball mill. After that, particles having a large particle size are removed to some extent, and further, crystallized glass powder and isopropyl alcohol as a dispersion medium are put into a ball mill, and milled over time to prepare a slurry. Other dispersion media include isobutyl alcohol, ethanol, acetone, MIBK, etc.
Since isopropanol is the most excellent from the viewpoint of workability, isopropanol was used as the dispersion medium in the present invention.

Put the slurry prepared by the above method in the electrolytic cell, and also install the metal base material that has been sufficiently degreased and washed in the electrolytic cell, and the distance between the electrodes is 2 to 4 cm, and the glass particles are metal-based at the DC voltage of 150 to 600 V After electrophoretic electrodeposition on the material and drying the glass coating layer, baking is performed in a baking pattern as shown in FIGS. 4 to 6,
2 The insulating holo layer of FIG. 2 is obtained.

In particular, when forming the insulating holo layer, the most important point is the method of firing, and the glass is once fired in an intermittent or continuous firing pattern as shown in FIGS. 4 to 6. It is preferable to perform a heat treatment at a temperature within the range from the softening point to the crystal starting point, and then perform firing at a working temperature. FIG. 4 shows the firing pattern when the substrate coated with the glass layer was heat-treated at 700 ° C. for 30 minutes, cooled, and further fired at 900 ° C. Similarly, FIG.
The temperature is continuously raised and held at 700 ° C and 900 ° C for 1 hour each. These firing patterns are based on the softening point Ts of the DTA curve of the crystallized glass of Table 2 a shown in FIG.
From the crystallization start point Tc to the crystallization start point Tc. Heat treatment below the softening point or above the crystallization start point, and smooth insulation even if baked at a working temperature of 900 ° C The holo layer cannot be obtained. Similarly, in the firing pattern of Fig. 10, 90
Even if baked at 0 ° C for 10 minutes, a smooth surface with Ra of 0.15 or less cannot be obtained.

The present invention, for heat treatment for a long time at a temperature that sufficiently softens, the unevenness of the coated glass surface flows and is leveled,
The surface becomes smooth. On the other hand, at a temperature lower than the softening point, the glass particles do not soften or flow, and the surface remains in a concavo-convex state. Therefore, the surface will not be smooth even if fired at 900 ° C next time. On the contrary, even above the crystallization start point,
Since it exceeds the softening and flowing regions of the glass, the surface is not leveled and crystallization proceeds, so that a waviness or a holo layer with a large Ra tends to be formed. As described above, in order to make the holo surface smooth, it is important to perform heat treatment and leveling for a sufficiently long time in the temperature range in which the glass softens and flows. The conventional method of raising the temperature to calcination and firing is not preferable.

An Au-metal organic layer is printed on an insulating hollow substrate formed by heat treatment at a temperature between the softening point and the crystallization start point described above, and baked at 800 ° C. for 5 minutes to form an Au electrode. A resistor paste made of RuO ₂ / glass frit is printed and fired on this electrode to form a resistor, and a glass glaze overcoat layer is further printed and fired to form the thermal head shown in FIG.

Next, some specific examples of the present invention will be described.

Example 1 A substrate coated with a glass layer by electrophoretic electrodeposition was heat-treated at 700 ° C. for 30 minutes, cooled, and further baked at 900 ° C. for 10 minutes in the baking pattern of FIG. 4 to form an insulating holo layer. Formed. An electrode, a heating resistor and an overcoat layer were formed on the holo layer by the method described above to form a thermal head.

Example 2 A substrate coated with a glass layer was continuously heated to 900 ° C. and held at 700 ° C. and 900 ° C. for 1 hour to form an insulating holo layer in the firing pattern shown in FIG. A thermal head was formed.

Example 3 Similarly, a substrate coated with a glass layer was heat-treated at 750 ° C. for 30 minutes in the firing pattern shown in FIG. 6, cooled, and further heated at 900 ° C.
It was baked for 10 minutes to form an insulating holo layer, and a thermal head was formed.

[Comparative Example 1] Similarly, in the firing pattern of FIG. 7, heat treatment was performed at 680 ° C. for 30 minutes, cooling, and further firing at 900 ° C. for 10 minutes to form an insulating holo layer to form a thermal head. did.

[Comparative Example 2] Similarly, in the same manner as the firing pattern of FIG. 8, heat treatment was performed at 770 ° C. for 30 minutes, cooling, and further firing at 900 ° C. for 10 minutes to form an insulating holo layer to form a thermal head. did.

Regarding the above Examples 1 to 3 and Comparative Examples 1 and 2, the center line plane roughness Ra of the insulating holo layer and the resistance variation of the heating resistor of the thermal head were measured.

The results are shown in Table 1.

Further, in the conventional example shown in Table 1, a thermal head is formed on an insulating hollow substrate fired in the firing pattern shown in FIG.

As shown in Table 1, the insulating holo substrate formed by the method of the present invention and the thermal head formed on the surface of the insulating holo substrate have a surface roughness higher than that of the conventional holo substrate.
It can be seen that the resistance value variation is excellent, and that heat treatment is once performed at a temperature within the range from the softening point of the glass to the crystallization start point and firing at the working temperature improves the surface property.

Example 4 Alkaline earth metal oxides (MgO, CaO,
The reason why BaO, ZnO) must be at least 15% by weight and the alkali metal oxide (Li ₂ O, Na ₂ O, K ₂ O) must be 2% by weight or less will be explained.

For the glass compositions shown in the following table, an insulating holo layer was formed by electrophoretic electrodeposition, and the surface roughness and electrophoretic electrodeposition of the substrate were examined. The results are shown in Table 2. The forming method is the same as in the second embodiment.

From the above results, it is essential that the alkaline earth metal content is at least 15% by weight and the alkaline metal content is 2% by weight or less.

[Embodiment 5] In the same manner as in Embodiment 2, the thrust bearing portion 6 of the motor shown in Fig. 3 was coated with the insulating hollow layer 7 to form a compact disc motor.

[Comparative Example 3] In the firing pattern of Fig. 9, the thrust bearing portion was similarly coated with an insulating holo layer to form a motor.

Comparative Example 4 As a conventional comparative example, a motor was formed by using alumina for the bearing portion.

With respect to these, the amount of wear of the bearing portion was examined. The results are shown in Table 3.

As described above, it is understood that the wearability is improved even when the forming method of the present invention is applied to a small motor.

EFFECTS OF THE INVENTION As described in detail above, the insulating holo layer formed by heat treatment at a temperature within the range from the softening point of glass to the crystallization start point and further firing at the working temperature has a smooth surface of the insulating holo layer. It is possible to form a thermal head having a longer life and a small variation in resistance value and a small contact resistance between the electrode and the heating resistor. In addition, when applied to a motor, it is possible to significantly improve wear resistance, wow and flutter noise characteristics, etc., and it is also possible to significantly contribute to downsizing of equipment, improvement of reliability, and extension of life. Become.

[Brief description of drawings]

FIG. 1 is a process diagram showing a method of forming an insulating holo layer according to an embodiment of the present invention, FIG. 2 is a sectional view of a thermal head which is an application example of the present invention, and FIG. 3 is an application example of the present invention. Sectional views of small motors, FIGS. 4, 5, and 6 are temperature characteristic diagrams showing firing patterns of examples of the present invention, and FIGS. 7 and 8 are temperature characteristics showing firing patterns of comparative examples. FIG. 9 is a DTA curve of the crystallized glass used in the present invention, and FIG. 10 is a temperature characteristic diagram showing a conventional firing pattern. 1 ... Metal substrate, 2 ... Insulating holo layer, 3 ... Electrode, 4
...... Heating resistor, 5 ・ ・ ・ Abrasion resistant layer, 6 ・ ・ ・ Thrust bearing part, Ts ・ ・ ・ Softening point, Tc ・ ・ ・ Crystallization starting point.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Ikeda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoshihiro Watanabe 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yasuo Mizuno 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A SiO ₂ —B ₂ O ₃ —MgO—BaO system containing at least 15% by weight of an oxide of an alkaline earth metal on a metal substrate, and a monovalent alkali metal oxide of 2 After coating a fine powder of crystallized glass having a composition of less than or equal to weight percent, heat-treated at a temperature within the range of the crystallization start point from the softening point of the crystallized glass, further higher than the heat treatment temperature of the crystallized glass A method for forming an insulating holo layer, which comprises firing at a temperature to form an insulating holo layer. 2. The method for forming an insulating holo layer according to claim 1, wherein a fine glass powder is coated on the metal substrate by an electrophoretic electrodeposition method.