JPH0714647B2 - Thermal head and manufacturing method thereof - Google Patents

Description

The present invention relates to a thermal head and a manufacturing method thereof.

[Conventional technology]

A thermal head is one in which a pair of electrode conductors are formed on an insulating substrate, and a resistor that is electrically connected to each electrode conductor is also formed. A recording current is applied to the body and the Joule heat generated in the resistor is used to color the thermal paper in contact with the resistor, or the thermal transfer ink layer is melted and transferred to the recording paper to transfer information such as characters. Is used to record.

FIG. 3 is a cross-sectional view of a thick film thermal head. (1) is an insulating substrate, (2) is a glaze layer, (3) is an electrode conductor formed in a desired pattern on the glaze layer (2),
Reference numeral (4) is a resistor, which is electrically connected to the electrode conductor (3) and is supplied with a signal current through the electrode conductor (3) to generate Joule heat. (5) is a wear resistant layer.

Next, the manufacturing process of the conventional thick film type thermal head will be described with reference to FIG.

A particle size of about 1 μm on the entire surface of the insulating substrate with a glaze layer, in which a glaze layer (2) with a thickness of about 50 μm is formed on the surface of an insulating substrate (1) made of alumina ceramic with a thickness of about 1 mm. The step of printing the inorganic gold paste containing the gold particles by a method such as screen printing and firing is repeated a few times to form a gold thin film having a thickness of about 3 μm.

Next, an electrode conductor (3) having a desired pattern is formed by photoetching using a predetermined mask.

Next, a resistor paste containing ruthenium oxide with a particle size of about 5 μm, high melting point frit glass, and zirconium oxide as components is printed in a thin line shape and fired at about 800 to 830 ° C to obtain a resistance of about 10 μm in height. Form the body (4).

Next, high melting point frit glass was coated with SiO ₂ , Al ₂ having a particle size of 0.5 μm.
Glass paste containing about 25% O ₃ is used as a resistor (4).
Printing is performed so as to cover the upper side, and baking is performed at a temperature lower than the baking temperature of the resistor (4) (780 to 810 ° C. in this example) to form the abrasion resistant layer (5) having a thickness of about 8 μm.

Next, the IC is mounted on an insulating substrate (1), wire bonding is performed to connect the electrode conductor (3) and the IC, and the IC, the wire bonding portion and the electrode conductor (3)
A thick film type thermal head is completed by performing molding to cover the exposed part of.

[Problems to be Solved by the Invention]

In the conventional thick film thermal head, the thickness of the electrode conductor (3) is required to be 3 μm or more. This is because the particle size of the gold particles contained in the inorganic gold paste is as large as about 1 μm, and therefore a thin gold thin film may cause pattern breakage or peeling during wire bonding.

However, if the thickness of the electrode conductor (3) is large, it is difficult to miniaturize the electrode pattern because the etching factor during photo-etching for forming the electrode conductor (3) is required to be about 20 μm. Since the variation in the resistance value between the electrode conductors (3) becomes large and the density unevenness of the printed image quality becomes large, it is difficult to make the printing dots fine.

Further, if the electrode conductor (3) is thick, the surface of the abrasion resistant layer (5) will have large irregularities, and the contact state with the thermal recording paper will be poor, so that high-quality printing at high speed was not possible.

Furthermore, if the electrode conductor (3) is thick, a large amount of Joule heat generated in the resistor (4) will escape through the electrode conductor (3), so the resistor (4) is required to print at 250 to 600 ° C. The input required to heat up to the extent increased and a large drive power was required.

The present invention has been made in order to solve the above problems. Even if the electrode conductor is thin, pattern breakage or peeling at the time of wire bonding is unlikely to occur, miniaturization of printing dots is possible, and driving power is small. An object is to provide a thermal head and a method for manufacturing the same.

[Means for Solving the Problems]

In the thermal head according to claim 1, a glaze layer is provided on an insulating substrate, and the film thickness is 0.15 to 1.0 μm on the glaze layer.
m is formed by printing and firing an organic gold paste to provide a conductor thin film to provide an electrode conductor having a wire bonding portion on which a desired pattern is formed, and a resistor is provided on a predetermined portion of the electrode conductor and on the glaze layer. The heating resistor is formed, and the connecting member is wire-bonded to the wire bonding portion of the electrode conductor to electrically connect to the IC.

In the method of manufacturing a thermal head according to claim 2, a glaze layer is formed on an insulating substrate, and a film thickness is formed on the glaze layer.
An organic gold paste having a thickness of 0.15 to 1.0 μm is provided, an electrode conductor having a desired electrode pattern is formed by etching, a resistor is provided on a predetermined portion of the electrode conductor and the glaze layer to form a large number of heating resistors, Thereafter, a voltage pulse is applied to the heating resistor via the electrode conductor to adjust the resistance value to fall within a predetermined range, and then wire bonding is performed on the electrode conductor.

[Action]

The electrode conductor according to claim 1 has strong adhesive strength with the glaze layer and is uniform even if a thin electrode pattern having a film thickness of 0.15 to 1.0 μm is formed by printing and firing an organic gold paste. Since a flat surface can be formed, pattern breakage and peeling during wire bonding are less likely to occur.

In the method of manufacturing a thermal head according to claim 2, an organic gold paste having a film thickness of 0.15 to 1.0 μm is provided on the glaze layer, an electrode conductor of an electrode pattern is formed by etching, and then a resistor is provided. After forming a large number of heating resistors, a voltage pulse is applied to the heating resistors via the electrode conductors to adjust the resistance value of each heating resistor to fall within a predetermined range. Since wire bonding is performed, the etching factor at the time of etching for forming the electrode conductor can be made zero, the driving power of the thermal head can be reduced, and the unevenness of the surface of the abrasion resistant layer can be reduced,
The printing dots can be miniaturized and the printing speed can be increased, and the variation in the resistance value of each heating resistor can be corrected.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a manufacturing process chart showing an embodiment of a thermal head according to the present invention. The structure of the thermal head manufactured by this manufacturing process is compared with that of the conventional thick film type thermal head shown in FIG. Since the electrode conductor (3) is thin, which is a fraction of the thickness, the detailed description thereof will be omitted.

In FIG. 1, the points different from the conventional structure process shown in FIG. 4 will be described with reference to FIG.

A gold thin film having a thickness of 0.4 to 0.6 μm is formed on the glaze layer (2) of the insulating substrate (1) by printing and firing using an organic gold paste. Metal organic A-4615 manufactured by Engelhard Co., Ltd. is used as the organic gold paste, which is printed and fired at a firing temperature of 600 to 850 ° C.

A thick film glass material is used for the glaze layer (2). That is, since the glass frit or the like is added, the adhesive strength between the glaze layer (2) and the organic gold paste is strong, and for example, the gold pattern on the glaze layer (2) is peeled off with cellophane tape. Even if a peeling test or the like was performed, no problem in adhesive strength occurred.

Next, an electrode conductor (3) having a desired fine pattern is formed by a photo-etching method using a mask, and thereafter, a resistor (4) and an abrasion resistant layer (5) are formed in the same process as the conventional process. It

In addition, since the film quality of the electrode conductor (3) using the organic gold paste has a uniform and flat surface, the adhesive force to the gold wire which is a connecting member (not shown) at the time of wire bonding is also strong. .

Actually, when the organic gold paste was formed on the grace layer (2) and the film thickness was 0.15 to 1.0 μm, the peeling condition at the time of wire bonding was examined, and the result was as shown in FIG.

In the figure, the horizontal axis represents the film thickness (μm) and the vertical axis represents the peel strength (g · f).

As is apparent from this figure, when the organic gold paste is formed on the glaze layer (2) and the film thickness is 2 to 3 μm, the peel strength at the time of wire bonding is 8 gr. When the organic gold paste was formed on the glaze layer (2) and the film thickness was 0.15 to 1.0 μm, the peel strength during wire bonding was 10 gr.

Next, a voltage pulse is applied while measuring the resistance value between the electrode conductors (3), and voltage pulse trimming is performed so that each resistance value is adjusted to fall within a predetermined range.

This voltage pulse trimming was previously performed by the applicant of the present invention in Japanese Patent Application No.
It was filed as No. 205012 “Method for manufacturing thermal head”.

This is, for example, a step of applying a pulse group with a unit of a voltage pulse of 1 μs to a resistor (4) of 1 unit via an electrode conductor (3) and measuring the resistance value of the resistor. , Is applied to the resistor (4) between all the electrode conductors (3) while gradually increasing the applied pulse voltage until the resistance value falls within a predetermined range, for example, within ± 10% of the reference value. is there.

When a voltage pulse is applied, the resistance value decreases because the inhomogeneous coupling of Me-Is-Me (metal-insulator-metal) at the contact interface between ruthenium oxide and frit glass that compose the resistor (4). It can be presumed that the state of applying the voltage pulse changes the state of coupling of Me-Is-Me, and the specific resistance of the resistor (4) gradually decreases.

After the voltage pulse trimming is completed, the same steps of IC mounting, wire bonding, and molding as the conventional manufacturing process are completed, and the thermal head manufacturing process is completed.

Thus, using the organic gold paste, the glaze layer (2)
Since a thin film of the electrode conductor (3) having a thickness of 0.4 to 0.6 μm is formed on the upper surface and an electrode pattern is formed on the thin film of the electrode conductor by the photo etching method, the etching factor can be made substantially zero. The electrode pattern can be miniaturized.

Further, the resistance value between the electrode conductors (3) is adjusted by performing electrode pulse trimming one unit at a time so that the dispersion of the resistance value is within ± 10%, so that the uneven density of printing does not occur.

In addition, since the unevenness of the surface of the abrasion resistant layer is reduced and the contact state with the thermal recording paper is improved, the printing dots can be miniaturized and the printing speed can be increased.

Furthermore, since the electrode conductor (3) is a thin film, the heat energy that escapes through the electrode conductor (3) is reduced and the driving power of the thermal head can be reduced.

FIG. 2 is a characteristic diagram comparing the driving power of one embodiment of the present invention with that of a thin-film thermal head. The vertical axis represents print density (OD) and the horizontal axis represents heat generation energy (mj) of the resistor. The thermal heads of the examples shown in solid line A are about 2.
While it is 5 mj, it shows that a driving power equal to or less than that of the thin-film thermal head shown by the chain line B is sufficient.

In the thermal head of the comparative example, the glaze layer (2) has a thickness of 55 μm, the abrasion resistant layer (5) has a thickness of 8 μm, the heating resistor area is 0.10 × 0.175 mm ² , the resolution is 8 dots / mm, and the resistance value is Variation of ± 10%.

The driving power of the conventional thermal head in which the thickness of the electrode conductor (3) is 3.5 μm and the thermal head of this embodiment in which the thickness is 0.6 μm is 100% for the former, the latter is 60% is enough and 40% can be reduced.

〔The invention's effect〕

The thermal head according to the present invention forms a conductor thin film by printing and firing an organic gold paste having a film thickness of 0.15 to 1.0 μm on the glaze layer on the insulating substrate. Since it can be miniaturized and has a uniform and flat surface, wire bonding can be performed by providing a wire bonding portion on the electrode pattern, the adhesion strength is strong, peeling is difficult, and the quality is improved.

Further, since the thermal energy that escapes through the electrode conductor is reduced, the driving power can be reduced.

Further, the unevenness of the surface of the abrasion resistant layer is reduced, so that the printing dots can be made finer and the printing speed can be increased.

In addition, since a large number of heating resistors are formed by the resistors and the resistance value is adjusted by applying a voltage pulse to the heating resistor via the electrode conductor, there is less variation in the resistance value of the heating resistor. As a result, it is possible to prevent uneven printing density.

Furthermore, since the printing dots can be made finer and unevenness in printing density can be prevented, the printing resolution can be improved and the thermal head can be miniaturized.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of one embodiment of the present invention, and FIG.
FIG. 3 is a comparison diagram of printing characteristics between an embodiment of the present invention and a thin film type thermal head, FIG. 3 is a sectional view showing a general structure of a thick film type thermal head, and FIG. 4 is a conventional thick film type thermal head. FIG. 5 is a diagram showing the manufacturing process of, and FIG. 5 is a diagram for explaining the peeling property of the electrode conductor. (1) ... Insulating substrate, (2) ... Glaze layer, (3)
...... Electrode conductor, (4) ...... Resistor, (5) …… Abrasion resistant layer. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. An insulating substrate, a glaze layer provided adjacent to the insulating substrate, and a film thickness on the glaze layer.
An electrode conductor in which an organic gold paste having a thickness of 0.15 to 1.0 μm is printed and fired to form a conductor thin film to form a desired pattern, and a part of the desired pattern is formed as a wire bonding portion, and the above wire bonding of the electrode conductor. Other than a predetermined part and on the glaze layer, which forms a large number of low-heat-generating antibodies, one end of this resistor is wire-bonded to the wire bonding part of the electrode conductor, and the other end is electrically connected to the IC. A thermal head comprising: a connection member that is electrically connected. 2. A step of forming a glaze layer on an insulating substrate, and a conductor thick film is formed by printing and firing an organic gold paste having a film thickness of 0.15 to 1.0 μm on the glaze layer, and wire bonding is performed by etching. A step of forming an electrode conductor having a desired electrode pattern having a portion, a step of providing a resistor on a predetermined portion of the electrode conductor and the glaze layer to form a large number of heating resistors, and then through the electrode conductor. And a step of applying a voltage pulse to the heating resistor to adjust the resistance value of the heating resistor within a predetermined range, and wire bonding to the electrode conductor. Head manufacturing method.