JPH08281990A - Thermal print head - Google Patents

Thermal print head

Info

Publication number
JPH08281990A
JPH08281990A JP8514295A JP8514295A JPH08281990A JP H08281990 A JPH08281990 A JP H08281990A JP 8514295 A JP8514295 A JP 8514295A JP 8514295 A JP8514295 A JP 8514295A JP H08281990 A JPH08281990 A JP H08281990A
Authority
JP
Japan
Prior art keywords
sealing
organic resin
resin material
print head
driving ic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP8514295A
Other languages
Japanese (ja)
Inventor
Fumiko Tsuda
文子 津田
Original Assignee
Toshiba Corp
株式会社東芝
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toshiba Corp, 株式会社東芝 filed Critical Toshiba Corp
Priority to JP8514295A priority Critical patent/JPH08281990A/en
Publication of JPH08281990A publication Critical patent/JPH08281990A/en
Pending legal-status Critical Current

Links

Abstract

(57) [Abstract] [Purpose] By using an organic resin material as the sealing means, the miniaturization thereof is promoted and the generation of bubbles generated when the organic resin material is thermally cured is prevented. To improve the image quality by improving the sealing property between them and the running property of the thermal paper. A first bonding wire 16 on the running side of the thermal paper 22 is sealed with a first sealing material 18 having a low thixotropic property and an aspect ratio of 0.13 to prevent the occurrence of air traps, Prevent the generation of bubbles. On the other hand, the gap 23
Ceramic board 11 and circuit board 12 that are adjacent to each other via
The second bonding wire 17 extending over the second sealing material 2 having a high thixotropic property and an aspect ratio of 0.22.
The sealing material is sealed at 0 to prevent the sealing material from flowing into the gap 23 and suppress the air from the gap 23 from rising to the surface as bubbles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head for performing thermal printing with a plurality of heating resistors arranged on an insulating substrate, and more particularly to a connecting portion between its driving IC and the insulating substrate and circuit board. The present invention relates to improvement of a sealing means for sealing

[0002]

2. Description of the Related Art In a thermal print head in which a plurality of heating resistors provided on an insulating substrate are heated by a driving IC and a thermal printing is performed by an output device such as a printer, conventionally, a thermal print head shown in FIG. The drive IC and the substrate connecting portion are protected as shown in FIG. That is, the entire connecting portion between the ceramic substrate 1 and the circuit substrate 2, which are insulating substrates, and the driving IC 3 is sealed with a silicone rubber IC sealing resin 4, and a metal or resin cover is further provided thereon. It was covered with 6.

Since the cover 6 has a low hardness of the silicone rubber IC encapsulating resin 4, the mechanical strength is weak only with the silicone rubber IC encapsulating resin 4. Therefore, the cover 6 is driven during the manufacturing and mounting process of the thermal print head 7. The IC for use was prevented from being damaged. Further, since the surface of the silicone rubber IC sealing resin 4 of the cover 6 has an adhesive property, this adhesive property makes it possible to print the image with the thermal print head 7 at the time of printing.
The thermal paper 8 running in the vicinity is prevented from traveling, and the thermal paper 8 is prevented from being caught.

[0004]

Conventionally, as shown in FIG. 3, a cover 6 is further provided above the silicone rubber IC encapsulating resin 4 for encapsulating the driving IC 1, the insulating substrate 2 and the circuit board 3. It was covered.

However, if the cover 6 is further attached after being sealed with the resin 4, the flatness of the thermal print head 8 is lowered and the distance from the thermal paper 7 becomes uneven, so that the image quality is deteriorated. Had the problem of doing. Further, since a space for mounting the cover 6 on the silicone rubber IC sealing resin 4 must be secured, there is a problem that the miniaturization of the thermal print head 8 itself is hindered.

Therefore, it has been conventionally provided by sealing the connecting portions of the substrates 2 and 3 and the driving IC 1 with an organic resin material having a high hardness after curing and having no adhesiveness on the surface. Abolition of cover 6 is being considered. However, in this case, it is necessary to ensure that the surface after curing does not have peculiar irregularities or holes in order to secure the sealing property and not to impede the running property of the thermal paper.

However, the thermal print head is
As a main mechanism of bubble generation due to the configuration, firstly, air in the gap between the insulating substrate and the circuit substrate becomes bubbles. Secondly, when the organic resin material is applied onto the bonding wire, the organic resin material does not wrap around the lower portion of the bonding wire to create an air pocket, which becomes a bubble.

On the other hand, since the organic resin material is a thermosetting resin, it starts to cure at a predetermined temperature, but has a characteristic that the viscosity sharply decreases at a predetermined temperature not lower than room temperature and not higher than the curing temperature.

For this reason, when the organic resin material is subjected to thermal curing with air in the gap between the substrates or with air traps under the bonding wires, the gap is reduced at a predetermined temperature at which the viscosity sharply decreases. Bubbles are generated from the air pockets and reach the surface of the organic resin material. After curing, these become irregularities and holes on the surface.

Then, the projections due to such irregularities and holes are
This has hindered the thermal paper from running, and caused black streaks on the thermal paper due to pressure sensitivity, resulting in a new problem of degrading image quality. Also, if air bubbles continue from the air pockets or gaps to the surface, the sealing property will be destroyed and the conductor pattern or bonding wire formed on the substrate surface will be exposed to the external environment. Due to the mechanical shock and poor moisture resistance, the image quality is deteriorated and the image becomes unusable.

Therefore, the present invention solves the above-mentioned problems, and in order to miniaturize the thermal print head, an organic resin material having high hardness and no tackiness is used.
Despite sealing between the board connecting part and the driving IC, by preventing the generation of bubbles during thermosetting, the thermal paper is prevented from being contaminated due to pressure sensitivity and the board is not impaired in sealing performance. Also, it is an object of the present invention to provide a thermal print head capable of surely protecting a driving IC.

[0012]

According to a first aspect of the present invention, there is provided an insulating substrate, a plurality of heating resistors arranged on the insulating substrate, and a plurality of heat generating members provided on the insulating substrate. A driving IC connected to the resistor, a circuit board adjacent to the insulating substrate and connected to the driving IC, and a connecting portion of the driving IC and the insulating substrate made of a first organic resin material. And a first sealing means for sealing
Second organic resin material having a thixotropy characteristic different from that of the second organic resin material, and a second sealing means for sealing the connecting portion of the circuit board via the driving IC and the insulating substrate. .

The invention described in claim 2 is the same as claim 1.
In, the thixotropy characteristic of the first organic resin material forming the first sealing means is 0.08 to 0.15 in aspect ratio.

Further, in the invention described in claim 3, in any one of claim 1 or claim 2, the thixotropy characteristic of the second organic resin material constituting the second sealing means has an aspect ratio of 0. .16 or more.

[0015]

The present invention is configured as described above, and seals between the driving IC and the insulating substrate and between the driving IC and the insulating substrate with organic resin materials having different thixotropy characteristics. As a result, at the time of thermosetting, air bubbles are not generated regardless of the decrease in viscosity of the organic resin material, deterioration of image quality is prevented, and reliable sealing of the substrate and the driving IC can be obtained.

[0016]

First, the principle of the present invention will be described. The following method can be considered in order to prevent bubbles from being generated when the substrate and the driving IC are sealed with an organic resin material.

First, a method of improving the thixotropic property of the organic resin material and suppressing the presence of air in the organic resin material without moving it to the surface, and second, a thixotropic property of the organic resin material. It is conceivable to lower the temperature so that when the organic resin material is applied, it enters into even a slight gap and does not create air traps that cause air bubbles.

However, when an organic resin material having a high thixotropic property is used, even if there are bubbles, they are suppressed and do not reach the surface. On the other hand, since the organic resin material has a low fluidity, a predetermined area When trying to seal
The height of the sealing portion is increased, and the rising angle of the organic resin material from the substrate is increased.

Therefore, if the rising angle of the sealing portion on the side of the heating resistor is large, it becomes difficult for the thermal paper running on the substrate to pass smoothly, and if the height of the sealing portion is further increased, the thermal paper is transferred to the heating resistor. The platen roller for making the sheet adhere to the sheet comes into contact with the sheet and the thermal paper cannot pass through.

On the contrary, when an organic resin material having a low thixotropy characteristic is used, no air pocket is formed, but if the organic resin material has too good fluidity, the shape as the sealing portion cannot be maintained and the resin flows. As a result, the bonding wire or the like is exposed, or the bonding wire or the like flows into the gap between the substrates endlessly and the sealing becomes impossible. Therefore, in actuality, the characteristics of the above-mentioned organic resin material are taken into consideration, and the thixotropy characteristics are controlled so as to be optimum, and the sealing between the drive IC and the substrate is performed.

The present invention will be described below with reference to an embodiment shown in FIGS. On the heat dissipation board 10a of the thermal print head 10, the ceramic board 1 which is an insulating board is provided.
1 and the circuit board 12 are provided adjacent to each other. 48 on the ceramic substrate 11 at intervals of 400 dot / int.
The heating resistors 13 of 00 dots are arranged in a line.
Reference numeral 14 is a driving IC provided on the ceramic substrate, and the heating resistor 13 and the circuit board 12 are connected to the driving IC 1 by the first and second bonding wires 16 and 17, respectively.
4 is connected.

On the first bonding wire 16 for connecting the heating resistor 13 and the driving IC 14, a ceramic (epoxy resin) ceramic paste 225 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a filler and silica (oxidation). Silicon (S
iO)) and has a low thixotropic property and an aspect ratio (ratio of diameter and maximum height when an arbitrary material is dropped on a glass plate and cured under predetermined curing conditions) is 0.1.
The first sealing material 18, which is the first sealing means 3, is applied. Further, on the second bonding wire 17 connecting the circuit board 12 and the driving IC 14, silica (silicon oxide (SiO)) is contained as a filler in the ceramic resin ceramicoat 225 (manufactured by Shin-Etsu Chemical Co., Ltd.). However, the second sealing material 20 which is the second sealing means having a higher thixotropic property than the first sealing material 18 and an aspect ratio of 0.22 is applied.

The first and second sealing materials 18 and 20 are
Immediately after the coating, it swells to some extent as shown in FIG. 1, but after that, by heating at 120 ° C. for about 2 hours to cure, it is cured into a smooth shape as shown in FIG.

Reference numeral 21 is a platen roller, and 22 is a thermal paper which is inserted between the platen roller 21 and the heating resistor 13 and printed while running. Reference numeral 23 is a gap formed between the ceramic substrate 11 and the circuit substrate 12.

According to this structure, the first and second sealing materials 18 and 20 have the necessary mechanical strength by themselves, and are non-adhesive, so that the sealing materials of the prior art can be improved. Since it is not necessary to further provide a cover on the top, the space for the cover can be saved, and the thermal print head 10 can be downsized.

On the side of the first bonding wire 16, the thixotropy characteristic is low, and the first sealing material 18 that flows well under the first bonding wire 16 is used for sealing. Unlike the conventional case, since air pockets are not generated in the first encapsulant 18 and bubbles are not generated during heat curing, the first encapsulant 18 allows the first bond-in wire 16 to be formed. The surface can be reliably sealed with a smooth surface. Therefore, unlike the conventional case, the image quality can be improved without causing black streaks on the thermal paper 22 due to the pressure sensitivity due to the projections on the surface generated by the bubbles. Moreover, since the rising angle of the first sealing material 18 from the ceramic substrate 11 is gentle and the height of the first sealing material 18 does not rise, the first sealing material 18 is gentle. There is no fear that 18 will come into contact with the platen roller 21, and there is no fear that the traveling of the thermal paper 22 toward the heating resistor 13 will be hindered.

On the other hand, the ceramic substrate 11 and the circuit substrate 1
On the side of the second bonding wire 17 where the gap 23 is formed between the two, the thixotropic property is high, and the gap 2
Since the second sealing material 20 is sealed by the second sealing material 20 that does not flow into 3 or move bubbles to the surface, the surface of the second bonding wire 17 is also smooth by the second sealing material 20. It is possible to surely seal in such a state. The rising angle of the second sealing material 20 from the circuit board 12 is the first angle.
It is steeper than the sealing material 18 and its height is
It rises higher than the height of the encapsulant 18, but the thermal paper 2
There is no problem because it is not on the 2nd running side.

Moreover, the first and second sealing materials 18, 20
The content of silica is different in order to change the thixotropy characteristics, but since the content rate is small, the material characteristics of both sealing materials 18, 20 can be kept the same except for the thixotropy characteristics. There is no adverse effect on the control of the heating resistor 13 by the IC 14 for use.

The present invention is not limited to the above-mentioned embodiments, and various design changes can be made, and an epoxy resin may be used as long as it is an organic resin material. Further, the range of the aspect ratio of the first sealing means having a small thixotropy is arbitrary, but according to the coating experiment, when the aspect ratio becomes 0.07 or less, the material flows too much to seal the connection part. It was found that the shape could not be maintained and the bonding wire was exposed, while when the aspect ratio was 0.16 or more, the rising angle from the substrate became steep, which could adversely affect the running of the thermal paper. From this, in the first sealing means having a small thixotropy, the aspect ratio is 0.08.
When it is 0.15, the above problem does not occur, and the material flows under the bonding wire well, so that the sealing can be surely performed without generating bubbles.

On the other hand, the second sealing means having a large thixotropy for sealing on a plurality of substrates having a gap has an aspect ratio of 0.15 or less from a coating experiment. Material has flowed into the gap between the substrates,
It was found that the air in the gap could not control the rise to the surface. From this, in the second sealing means having a large thixotropy, if the aspect ratio is 0.16 or more, it is possible to surely perform the sealing without causing the material to flow into the gap and generate the bubbles. I can.

Further, the filler for controlling the thixotropic property is not limited to silica.

[0032]

As described above, according to the present invention, by using an organic resin material as the sealing means for sealing between the substrate and the driving IC, the strength required for mechanical protection of the driving IC or the like is improved. In addition, since the surface is non-adhesive, the cover conventionally provided above the sealing means is unnecessary, and the flatness of the thermal print head is improved and the image quality is improved. Be promoted.

Moreover, when the connection portion is sealed on the side of the thermal paper on which the thermal paper is run and there is no gap, the thixotropy characteristic is low, and air is trapped below the bonding wire. Since the sealing means made of a non-existent material is used, there is no fear that air bubbles will be generated during heat curing. or,
Since the rising of the sealing means from the substrate does not become steep and the height thereof does not rise, there is no fear that the sealing means comes into contact with the platen roller. Therefore, the thermal paper is smoothly moved by the platen roller, and black lines are not generated on the image due to the pressure sensitivity with the projections on the surface generated by the air bubbles as in the conventional case, and the image quality is improved.

On the other hand, when the connecting portion is sealed at the position where there is a gap between the two substrates, since the sealing means having high thixotropic property is used, the sealing means does not flow into the gap. In addition, since air from the gap can be prevented from moving to the surface of the sealing means during heat curing, the generation of bubbles continues to the surface, and there is no fear that the substrate, bonding wire, etc. will be exposed to the external environment. Sealing can be obtained, and adverse effects on image quality due to mechanical shock and poor moisture resistance can be eliminated, and image quality can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing first and second sealing materials before being cured in an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the time of printing by the thermal print head after curing the first and second sealing materials according to the embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a conventional thermal printhead.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Thermal print head 11 ... Ceramic substrate 12 ... Circuit board 13 ... Heating resistor 14 ... Driving IC 16 ... First bonding wire 17 ... Second bonding wire 18 ... First sealing material 20 ... Second Sealing material

Claims (3)

[Claims]
1. An insulating substrate, a plurality of heating resistors arranged on the insulating substrate, a driving IC provided on the insulating substrate and connected to the plurality of heating resistors, and the insulating property. A circuit board adjacent to the board and connected to the driving IC; and a first sealing means made of a first organic resin material and sealing a connecting portion of the driving IC and the insulating substrate.
A second organic resin material having a thixotropy characteristic different from that of the first organic resin material, and a second sealing means for sealing a connecting portion of the circuit board via the driving IC and the insulating substrate. A thermal print head that is characterized by
2. The thixotropic property of the first organic resin material forming the first sealing means has an aspect ratio of 0.0.
The thermal print head according to claim 1, wherein the thermal print head has a thickness of 8 to 0.15.
3. The thixotropic property of the second organic resin material constituting the second sealing means has an aspect ratio of 0.1.
It is 6 or more, Claim 1 or Claim 2 characterized by the above-mentioned.
The thermal print head according to any one of 1.
JP8514295A 1995-04-11 1995-04-11 Thermal print head Pending JPH08281990A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8514295A JPH08281990A (en) 1995-04-11 1995-04-11 Thermal print head

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8514295A JPH08281990A (en) 1995-04-11 1995-04-11 Thermal print head

Publications (1)

Publication Number Publication Date
JPH08281990A true JPH08281990A (en) 1996-10-29

Family

ID=13850419

Family Applications (1)

Application Number Title Priority Date Filing Date
JP8514295A Pending JPH08281990A (en) 1995-04-11 1995-04-11 Thermal print head

Country Status (1)

Country Link
JP (1) JPH08281990A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014080843A1 (en) * 2012-11-20 2014-05-30 京セラ株式会社 Thermal head and thermal printer provided with same
WO2015029913A1 (en) * 2013-08-26 2015-03-05 京セラ株式会社 Thermal head and thermal printer provided with same

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014080843A1 (en) * 2012-11-20 2014-05-30 京セラ株式会社 Thermal head and thermal printer provided with same
CN104812584A (en) * 2012-11-20 2015-07-29 京瓷株式会社 Thermal head and thermal printer provided with same
US9333765B2 (en) 2012-11-20 2016-05-10 Kyocera Corporation Thermal head and thermal printer equipped with the thermal head
JP5955979B2 (en) * 2012-11-20 2016-07-20 京セラ株式会社 Thermal head and thermal printer equipped with the same
WO2015029913A1 (en) * 2013-08-26 2015-03-05 京セラ株式会社 Thermal head and thermal printer provided with same
CN105408119A (en) * 2013-08-26 2016-03-16 京瓷株式会社 Thermal head and thermal printer provided with same
JPWO2015029913A1 (en) * 2013-08-26 2017-03-02 京セラ株式会社 Thermal head and thermal printer equipped with the same
CN105408119B (en) * 2013-08-26 2017-08-29 京瓷株式会社 Thermal head and the thermal printer for possessing the thermal head
US9844950B2 (en) 2013-08-26 2017-12-19 Kyocera Corporation Thermal head and thermal printer provided with same

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