JP2001063114A - Manufacture of thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture with high yield a thermal head wherein a driver IC is embedded in a hole on an insulating substrate. SOLUTION: In this manufacturing method, a thermal head 11 is manufactured by a process wherein a hole la is formed on an insulating substrate 1, a process wherein a transparent film 3 having a pressure sensitive adhesive on its lower face is adhered to the upper surface of the insulating substrate 1 such that the transparent film 3 covers the hole 1a and a driver IC 6 having a terminal electrode 7 provided on its upper face is disposed in the hole 1a in a condition that the driver IC 6 is attached to the lower face of the transparent film 3, a process wherein the transparent film 3 is processed to be in a predetermined pattern such that a through-hole 3a is formed on the transparent film 3 disposed right above the terminal electrode 7 and a process wherein a thermal head pattern consisting of a heating resistor 4 and a conductive layer 5 is provided on a portion from the upper face of the insulating substrate to the upper face of the transparent film 3 such that a part of the patterns 4, 5 is connected to the terminal electrode 7 through the through-hole 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermal head incorporated as a printer mechanism for a word processor, a facsimile or the like.

[0002]

2. Description of the Related Art In recent years, attempts have been made to make the surface of a thermal head in contact with a medium as flat as possible in order to perform thermal recording on a medium such as a plastic card which is difficult to bend using a thermal head.

As such a conventional thermal head, for example, as shown in FIG. 4, a hole is formed on the upper surface of an insulating substrate 11 on which a thermal head pattern comprising a plurality of heating resistors 12 and a conductive layer 13 is attached. A part 11a is provided,
A structure in which a driver IC 14 for controlling heat generation of the heating resistor 12 is embedded in the hole 11a is known. According to the thermal head shown in FIG.
Since C14 is buried in the hole 11a of the insulating substrate 11, there is no large protrusion on the upper surface of the insulating substrate 11, and printing is performed on a hard-to-bend medium such as a plastic card. Even in this case, the medium can be conveyed onto the heating resistor 12 in a substantially flat shape, and the thermal recording can be performed satisfactorily.

An adhesive 16 such as an epoxy resin is used for fixing the driver IC 14 to the hole 11a. First, the upper surface of the driver IC 14 on which the terminal electrode 15 is provided is fixed. It is arranged in the same plane as the upper surface of the insulating substrate 11 using a fixing jig or the like, and then the adhesive 16 is filled between the inner wall of the hole 11a and the side surface of the driver IC 14, and then cured. Done.

Thereafter, a thermal head pattern including a heating resistor 12 and a conductive layer 13 is attached and formed on the upper surface of the insulating substrate 11, the upper surface of the adhesive 16, and the upper surface of the driver IC 14 by a conventionally known thin film forming technique or the like. This completes the thermal head as a product. The connection between the conductive layer 13 and the driver IC 14 is performed by extending one end of the conductive layer 13 to the terminal electrode 15 on the upper surface of the driver IC when the thermal head pattern is formed by a thin film forming technique or the like. .

[0006]

However, according to the above-described conventional thermal head, when the driver IC 14 is fixed at a predetermined position in the hole 11a, first, the driver IC 14 is fixed.
The driver IC 14 is accurately positioned using a fixing jig or the like so that the upper surface of C14 is flush with the upper surface of the insulating substrate 11,
After the gap between the driver IC 14 and the hole 11a is filled with the adhesive 16, a complicated operation such as carefully removing the fixing jig is required so that the driver IC 14 and the like are not damaged.
Therefore, the manufacturing process of the thermal head becomes complicated, the mass productivity of the thermal head is remarkably reduced, and relatively large manufacturing equipment such as a fixing jig is required.

Further, according to the above-described conventional thermal head, the filling amount of the adhesive 16 must be accurately controlled in order to set the upper surfaces of the insulating substrate 11, the adhesive 16, and the driver IC 14 at the same height. Must. At this time, the adhesive
If the filling amount of 16 is too large or too small, a large step is formed between the upper surface of the insulating substrate, the upper surface of the adhesive, and the upper surface of the driver IC, and when the conductive layer 13 is formed by a thin film forming technique or the like, the conductive layer 13 However, there is a disadvantage that the wire is easily broken near the step.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and a method of manufacturing a thermal head according to the present invention comprises the steps of providing a hole in an insulating substrate and adhering an adhesive on the lower surface. A light-transmitting film is attached to the upper surface of the insulating substrate so as to cover the hole, and a driver IC having a terminal electrode on the upper surface is attached to the lower surface of the light-transmitting film in the hole. Disposing in a state, processing the light-transmitting film into a predetermined pattern so that a through-hole is formed in the light-transmitting film located directly above the terminal electrode, and transmitting the light from the upper surface of the insulating substrate. A thermal head pattern composed of a heating resistor and a conductive layer is applied to the upper surface of the transparent film such that a part of the pattern is connected to a terminal electrode through a through hole of the translucent film. It is characterized in that comprises a degree, the.

[0009] The method of manufacturing a thermal head according to the present invention is characterized in that the translucent film is formed of a photosensitive resin.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view of a thermal head manufactured by the manufacturing method of the present invention, FIG. 2 is a sectional view of the thermal head of FIG. 1, 1 is an insulating substrate, 1a is a hole, and 3 is a translucent film. , 3a are through holes, 4 is a heating resistor, 5 is a conductive layer, 6 is a driver IC, and 7 is a terminal electrode.

The insulating substrate 1 is, for example, 0.5 mm to 1.
A hole 1a penetrating the insulating substrate 1 in the thickness direction is provided on the upper surface thereof, and a translucent film 3 is attached so as to cover the hole 1a. ing.

On the upper surface of the insulating substrate 1, a partial glaze layer 2, a translucent film 3, a heating resistor 4, and a conductive layer 5 are adhered in a predetermined pattern, and a driver IC 5 is embedded in the hole 1a. I have.

The partial glaze layer 2 is applied in a strip shape on a part of the upper surface of the insulating substrate 1, and the glaze layer 2 is formed of a low heat conductive material such as glass so as to form a mountain-like cross section. Therefore, a large number of heating resistors 4 attached near the top are projected upward to effectively increase the printing pressure on the recording medium, and the heat generated by the heating resistors 4 in the partial glaze layer 2 is stored and accumulated. By dissipating the heat, the thermal response of the thermal head is maintained satisfactorily.

Further, the plurality of heat generating resistors 4 are provided, for example, at 300 dpi near the top of the partial glaze layer 2 described above.
Since the heating resistors 4 are made of an electric resistance material such as TaSiO or TiSiO, when the power is applied via a conductive layer 5 described later, When Joule heat is generated and printing is performed using, for example, an ink ribbon, a predetermined temperature required to melt the ink on the ink ribbon is reached.

The conductive layer 5 is for supplying power supply power or printing control signals to the driver IC 6 or for supplying the output of the driver IC 6 to the heating resistor 3. And a predetermined pattern on the upper surface of the partial glaze layer 2, the translucent film 3, etc.
It is formed.

On the other hand, the light-transmitting film 3 has an adhesive adhered to the lower surface thereof. When the driver IC 6 is fixed in the hole 1a, the light-transmitting film 3 completely covers the hole 1a. The adhesive is adhered to the upper surface of the insulating substrate 1 to hold the driver IC 6 at a predetermined position in the hole 1a with the adhesive.

The driver IC 6 attached to the lower surface of the translucent film 3 has a function of selectively causing the heating resistor 4 to generate Joule heat, specifically, image data supplied from the outside (printer main body). And a function of individually controlling the energization of the heating resistor 4 based on the printing control signal. On the upper surface, a plurality of terminal electrodes 7 and electronic circuits such as switching transistors, latches, and shift registers are formed. .

At this time, the driver IC 6 is connected to the insulating substrate 1
Because it is completely buried in the hole 1a, the surface of the thermal head in contact with the media is almost flat, and even when printing on hard-to-bend media such as a plastic card, Can be conveyed onto the heating resistor 4 in a substantially flat shape to perform good thermal recording.

The electrical connection between the conductive layer 5 and the terminal electrode 7 of the driver IC 6 is made by connecting one end of the conductive layer 5 from the upper surface of the insulating substrate 1 to the terminal electrode 7 via the upper surface of the light transmitting film 3. This is achieved by extending the extended portion to a terminal electrode 7 through a through hole 3 a provided in the light transmitting film 3.

A region surrounded by the translucent film 3, the side surface of the driver IC 6 and the inner wall of the hole 1a is filled with an adhesive 9, and the adhesive 9 allows the driver IC 6 to be inserted into the hole 1a. It is firmly fixed at a predetermined position inside.

In the above-described thermal head, for example, when printing is performed using an ink ribbon, the ink ribbon and the medium are conveyed onto the heating resistor 4 in a state where the ink ribbon and the medium are overlapped so that the ink ribbon is on the thermal head side. In addition, the heating resistors 4 are individually and selectively heated in accordance with the driving of the driver IC 6, and the heat of the ink ribbon is heated and melted by the generated heat, and the ink is adhered and transferred to the medium. Thus, a predetermined print is formed.

Next, a method for manufacturing the above-described thermal head will be described with reference to FIGS.

(1) First, as shown in FIG. 3A, a hole 1a is formed on the upper surface of an insulating substrate 1 having a partial glaze layer 2.

When the insulating substrate 1 is made of, for example, alumina ceramics, a ceramic material powder of alumina, silica, magnesia or the like is mixed with an appropriate organic solvent and a solvent to form a slurry, which is formed into a slurry by a conventionally known doctor blade. The ceramic green sheet is formed by adopting the method or the calendar roll method, and then
The ceramic green sheet is punched into a predetermined shape, and is manufactured by baking it at a high temperature. A glass paste is applied to the upper surface of the insulating substrate 1 thus obtained in a band shape by screen printing or the like, which is conventionally known, By baking this at a high temperature, a partial glaze layer 2 is formed.

The hole 1a is formed by irradiating a laser on the upper surface of the insulating substrate 1 after manufacturing the insulating substrate 1 as described above, or by forming the insulating substrate 1 by the above-described manufacturing method. By punching out the hole 1a in the state of a ceramic green sheet when manufacturing it,
1 in the thickness direction.

(2) Next, as shown in FIG. 3B, a light-transmitting film 3 is attached to the upper surface of the insulating substrate 1.

The light transmitting film 3 has a thickness of, for example, 3
It is formed of a UV-curable resin or the like having a thickness of from 50 μm to 50 μm, and a light-transmitting adhesive (not shown) is adhered to the lower surface thereof.

The light-transmitting film 3 has only to have an area at least larger than the opening of the hole 1a. Here, a film having substantially the same size as the insulating substrate 1 is used.

The translucent film 3 is adhered to the upper surface of the insulating substrate 1 so as to completely cover the hole 1a, whereby one opening of the hole 1a is completely closed by the translucent film 3. It has a loose shape.

Incidentally, a positioning marker for positioning the driver IC 6 in the step (3) described later is formed on the translucent film 3, and the marker has the same pattern as the terminal electrode 7 of the driver IC 6, for example. Is formed.

(3) Next, as shown in FIG. 3C, the driver IC 6 is arranged at a predetermined position in the hole 1a.

The driver IC 6 is inserted into the hole 1a through the other opening (opening on the lower surface side of the insulating substrate 1) of the hole 1a by using a vacuum suction collet or the like, and a predetermined portion of the lower surface of the translucent film is formed. Temporarily fixed in position.

This temporary fixing is performed by bringing the upper surface of the driver IC 6 into contact with the lower surface of the light-transmitting film 3 via an adhesive.
Is held on the lower surface of the light-transmitting film.

The positioning of the driver IC 6 with respect to the translucent film 3 is performed, for example, by using a CCD camera or the like when the positioning marker is formed in the same pattern as the terminal electrode 7 of the driver IC 6.
This is performed by matching the position of the terminal electrode 7 on the upper surface with the positioning marker.

At this time, since the light transmitting film 3 is formed of a light transmitting material and the lower surface side can be seen through from the upper surface side, when the driver IC 6 is temporarily fixed in the hole 1a, the driver IC 6 is temporarily fixed. The position of the IC 6 can be easily recognized from the upper surface side of the insulating substrate 1 through the translucent film 3, and the driver IC 6 can be accurately positioned.

(4) Next, an adhesive 9 is filled between the side surface of the driver IC 6 and the inner wall of the hole 1a to form a driver IC 6
Fix 6.

An epoxy resin or the like is used as the adhesive 9, and the adhesive 9 is filled by pouring a precursor such as an epoxy resin in a liquid form from the other opening of the hole 1a using a dispenser or the like. This is carried out by heating and polymerizing at a temperature lower than the thermal decomposition temperature of the polyimide resin forming the light-transmitting film 3, for example, at a temperature of 100 ° C. to 200 ° C., whereby the driver IC 6 is formed in the hole 1a.
Is fixed at a predetermined position in the inside.

At this time, one opening of the hole 1a (opening on the upper surface side of the insulating substrate 1) is completely closed by the translucent film 3, so that the filling amount of the adhesive 9 is too large. Even if it is too small or too small, no large step is formed from the upper surface of the insulating substrate 1 to the upper surface of the driver IC 6.

(5) Next, as shown in FIG. 3D, the light transmitting film 3 is processed into a predetermined pattern.

The processing of the light-transmitting film 3 is performed by employing a conventionally known photolithography technique and etching technique.
A through hole 3a is formed directly above the terminal electrode 7 of C6.

At this time, if an ultraviolet curable resin is used as the material of the light transmitting film 3, the light transmitting film 3
The transparent film 3 is partially cured by irradiating it with ultraviolet light of a predetermined wavelength in a predetermined pattern, and then immersed in a predetermined solvent to remove uncured parts, thereby easily patterning. Therefore, with the patterning of the light-transmitting film 3, a photoresist layer for patterning the light-transmitting film 3 may be separately formed on the light-transmitting film 3, or further processed after processing. There is an advantage that a complicated process such as peeling is not required, and the productivity can be improved.

(6) Finally, as shown in FIG. 3 (e), a thermal head pattern comprising a heating resistor 4 and a conductive layer 5 is applied from the upper surface of the insulating substrate 1 to the upper surface of the translucent film 3. Then, these are covered with a protective film 8.

The heating resistor 4 and the conductive layer 5 are made of a conventionally known thin film forming technique, specifically, TaS which becomes the heating resistor 4.
It is formed by sequentially depositing iO and Al to be the conductive layer 5 by a sputtering method or the like, and finely processing the TaSiO layer and the Al layer into a predetermined pattern by a photolithography technique and an etching technique.

At this time, one end of the conductive layer 5 constituting the thermal head pattern is extended to above the terminal electrode 7 of the driver IC 6 through the through hole 3a of the translucent film 3, and the extended portion is connected to the terminal. By making contact with the electrode 7, the driver IC 6 and the thermal head pattern are electrically connected.

The protective film 8 is formed by applying conventionally known sputtering, plasma CVD, or the like, and depositing Si ₃ N ₄ (silicon nitride), SiAlON (SiAlON) or the like on the thermal head patterns 4 and 5. 2 μm to 1
It is formed to a thickness of 5 μm, whereby a thermal head as a product is completed.

According to the method of manufacturing a thermal head of the present embodiment as described above, when the driver IC 6 is fixed at a predetermined position in the hole 1a, the driver IC 6 can be used without using a large-scale manufacturing facility such as a fixing jig. The alignment of the IC 6 can be easily and accurately performed through the translucent film 3. Therefore, connect the driver IC6 to the hole
The manufacturing process of the thermal head embedded in 1a is simplified, and the thermal head can be mass-produced.

According to the method of manufacturing a thermal head of this embodiment, one opening of the hole 1a (the opening on the upper surface side of the insulating substrate 1) is closed by the translucent film 3, and the driver IC 6 Since part of the adhesive 9 used to fix the thermal head pattern does not overflow above the opening of the hole 1a, a large step is formed in the area where the thermal head patterns 4 and 5 are applied. No thermal head patterns 4 and 5 can be formed as a good continuous film by a thin film forming technique or the like. Therefore, the production yield of the thermal head is improved.

Further, according to the method of manufacturing a thermal head of this embodiment, the light-transmitting film 3 used for temporarily fixing the driver IC 6 is left on the insulating substrate 1 as it is thereafter. The step of peeling the conductive film 3 is unnecessary, and the driver I, which is provided with an electronic circuit and the like when forming the thermal head pattern such as the heating resistor 4 and the conductive layer 5 by the thin film forming technique described above, is not necessary.
Corrosion of the upper surface of C6 by contact with an etching solution or the like is effectively prevented, thereby also improving the production yield of the thermal head.

Note that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, after the light transmitting film 3 is attached to the upper surface of the insulating substrate 1, the driver IC
6 is attached to the lower surface of the translucent film 3 by inserting it through the lower opening of the hole 1a, but instead of this, the driver I is attached to the lower surface of the translucent film 3 from the beginning.
C6 is attached and driver IC6 is inserted into the hole.
It may be attached to the upper surface of the insulating substrate 1 so as to be embedded in 1a, and in this case, the same effect as in the above-described embodiment can be obtained.

In the above-described embodiment, if the inorganic filler having an average particle diameter of 20 μm to 300 μm is previously filled between the side surface of the driver IC 5 filled with the adhesive 9 and the inner wall of the hole 1 a, this region can be obtained. When the adhesive 9 is poured into and cured, it is possible to effectively prevent the surface of the adhesive 9 from being cracked due to volume shrinkage.

[0053]

According to the present invention, when the driver IC is fixed at a predetermined position in the hole, the positioning of the driver IC can be performed through the translucent film without using a large-scale manufacturing facility such as a fixing jig. It can be done easily and accurately. Therefore, the manufacturing process of the thermal head in which the driver IC is embedded in the hole of the insulating substrate is simplified, and the mass production of the thermal head can be improved.

According to the invention, one opening of the hole is closed by the light-transmitting film.
Since a part of the adhesive or the like used to fix C does not overflow above the opening of the hole, a large step is formed in the area where the thermal head pattern is applied. However, the thermal head pattern can be formed as a good continuous film by a thin film forming technique or the like. Therefore, the production yield of the thermal head is improved.

Further, according to the present invention, since the light-transmitting film used for temporarily fixing the driver IC is left on the insulating substrate, the step of peeling the light-transmitting film is unnecessary. In addition, when a thermal head pattern such as a heating resistor or a conductive layer is formed by a thin film forming technique, the upper surface of a driver IC provided with an electronic circuit or the like is corroded by contact with an etching solution or the like. Is effectively prevented, which also improves the production yield of the thermal head.

[Brief description of the drawings]

FIG. 1 is a plan view of a thermal head manufactured by a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view of the thermal head of FIG.

FIGS. 3A to 3C are cross-sectional views for illustrating steps in a manufacturing method according to one embodiment of the present invention. FIGS.

FIG. 4 is a sectional view of a conventional thermal head.

[Explanation of symbols]

1 ... insulating substrate, 1a ... hole, 3 ... translucent film, 3a ... through hole, 4 ... heating resistor, 5
... Conductive layer, 6 ... Driver IC, 7 ... Terminal electrode

Claims (2)

[Claims] A step of providing a hole in the insulating substrate; and adhering a light-transmitting film having a lower surface covered with an adhesive to the upper surface of the insulating substrate so as to cover the hole.
Driver IC having a terminal electrode on the upper surface in the hole
Disposing the light-transmitting film in a state attached to the lower surface of the light-transmitting film; and processing the light-transmitting film into a predetermined pattern so that a through-hole is formed in the light-transmitting film located directly above the terminal electrode. A thermal head pattern composed of a heating resistor and a conductive layer from the upper surface of the insulating substrate to the upper surface of the light-transmitting film, and a part of the pattern is connected to a terminal electrode through a through hole of the light-transmitting film. A method for manufacturing a thermal head, comprising the steps of: 2. The method according to claim 1, wherein said light-transmitting film is formed of a photosensitive resin.