JP2000190543A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head high in reliability and productivity. SOLUTION: In a thermal head consisting of a head substrate wherein a plurality of heating elements and circuit conductors are deposited on a ceramic substrate and at least each one end portion of the circuit conductors are led out to one side of the upper surface of the ceramic substrate and a plurality of circuit terminals 5 are parallelly provided in the led-out portion and FRC wherein the circuit conductors are partially superposed along the side of the ceramic substrate 2 and a plurality of the wiring terminals 10 connected to the circuit terminals 5 by soldering are parallelly provided in the superposed portion, slits 5a, 10a are provided on both of the circuit terminals 5 positioned at both ends among a plurality of the circuit terminals 5 and the wiring terminals 10 connected to these terminals 5 by soldering in the directions of the terminals 5, 10 at right angles and the resin material 12 introduced into the gap between the head substrate and the FPC through the hole part 7a provided on the FPC positioned on the slits 5a, 10a is deposited on the upper surface of the head substrate, the upper surface of the FPC and the surface of solder 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a thermal head has been used as a printer mechanism such as a word processor.

[0003] Such a conventional thermal head, for example,
A plurality of heating elements and a plurality of circuit conductors arranged in a straight line are deposited on a square ceramic substrate, and at least one end of these circuit conductors is led out to one side of the upper surface of the ceramic substrate. A head substrate having a plurality of circuit terminals arranged side by side on a portion of the ceramic substrate having a plurality of circuit terminals arranged side by side, the plurality of circuit terminals being electrically connected to the circuit terminals at the overlapped portion; A flexible wiring board (hereinafter abbreviated as FPC) in which a plurality of wiring terminals are arranged side by side.

The FPC is for supplying external power, a print signal, and the like to a heating element and the like on a head substrate. A predetermined power is supplied to the heating element on the head substrate via the FPC. And the heating elements individually and individually generate Joule heat based on the print signal, so that a predetermined print is formed on the recording medium.

The circuit terminals and the wiring terminals are electrically connected by soldering or the like. In this case, first, the ends of the FPC where the wiring terminals are arranged side by side are connected to the circuit terminals. This is performed by superimposing along one side of the ceramic substrate, interposing solder between corresponding terminals, and heating and melting the solder with a heater bar or the like.

[0006]

However, in this conventional thermal head, the FPC has a structure in which a wiring conductor made of metal such as copper is sandwiched between a polyimide resin base film and a cover film. The thermal expansion coefficient of such an FPC is much larger than the thermal expansion coefficient of a ceramic-based head substrate. Therefore, when the temperature of the head substrate and the FPC becomes relatively high due to the use of the thermal head or the like, a large thermal stress is applied to the solder joints of both of them, especially the solder joints located at both ends. When thermal stress is repeatedly applied to the head substrate and the FPC, there is a disadvantage that the solder joint is broken and the FPC comes off the head substrate.

In the above-described conventional thermal head, the base film supporting the wiring terminals of the FPC is made of a polyimide resin or the like having low translucency, so that the positions of the wiring terminals are difficult to recognize. Therefore, in connecting the FPC to the head substrate and assembling the thermal head, when visually aligning with reference to the position of the wiring terminal, the workability is poor, and a high degree of skill is required to accurately perform the alignment. At the same time, it took a long time to assemble, and the productivity of the thermal head was significantly reduced.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and a thermal head according to the present invention has a plurality of heating elements linearly arranged on a square ceramic substrate. And a plurality of circuit conductors, and at least one end of each of the circuit conductors is led out to one side of the upper surface of the ceramic substrate, and a plurality of circuit terminals are juxtaposed with the lead portion. A flexible wiring board, which is partially overlapped along one side of the provided ceramic substrate, and in which a plurality of wiring terminals to be soldered to the circuit terminals are juxtaposed on the overlapped portion. Both the circuit terminals located at both ends of the circuit terminals and the wiring terminals soldered to the circuit terminals are provided with slits in a direction orthogonal to the direction in which these terminals are arranged, and A resin material introduced between the head substrate and the flexible wiring substrate through a hole formed in the flexible wiring substrate located on the lit is applied to the upper surface of the head substrate, the upper surface of the flexible wiring substrate, and the surface of the solder. It is characterized by the following.

Further, the thermal head according to the present invention is characterized in that the circuit terminal provided with the slit is commonly connected to all the heating elements.

Further, the thermal head according to the present invention is characterized in that the hole of the flexible wiring board is narrower by 10% to 30% than the slit width of the circuit terminal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a plan view of a thermal head according to one embodiment of the present invention, FIG. 2 is an enlarged view of a portion A in FIG. 1, FIG. 3 is a sectional view taken along line XX of FIG. 1, and FIG. And
1 is a head substrate, 2 is a ceramic substrate, 3 is a heating element,
4 is a circuit conductor, 5 is a circuit terminal, 7 is a flexible wiring board (FPC), 9 is a wiring conductor, 10 is a wiring terminal, 11 is solder, and 12 is a resin material. In the enlarged view of FIG. 2,
The illustration of the resin material 12 is omitted to more clearly show the positional relationship between the slit 5a and the hole 7a.

The head substrate 1 has a predetermined square shape. The head substrate 1 has a plurality of heating elements 3 and a plurality of circuit conductors 4 covered on a top surface of a ceramic substrate 2 in a predetermined pattern. At the same time, one end of each of the circuit conductors 4 is led out to one side of the upper surface of the ceramic substrate, and a plurality of circuit terminals 5 are juxtaposed at the lead portion.

The ceramic substrate 2 is made of a ceramic material such as alumina ceramics, and functions as a supporting base material for supporting the heating element 3, the circuit conductor 4, the driver IC 6 and the like on the upper surface thereof.

When the ceramic substrate 2 is made of alumina ceramics, an appropriate organic solvent and a solvent are added to and mixed with ceramic raw material powder such as alumina, silica, magnesia, etc. to form a slurry. The ceramic green sheet is obtained by employing the doctor blade method, the calendar roll method, or the like, and is punched into a predetermined square shape and fired at a high temperature.

The heating elements 3 are linearly arranged at a predetermined pitch (for example, at a pitch of 62.5 μm), each of which is a Ta-Si-O-based, Ti-Si-O-based, or Ti-C-based. -Because it is made of an electric resistance material such as Si-O type, Joule heat is generated when electric power is supplied from the outside via the circuit conductor 4 or the wiring conductor 9 of the FPC 7 which will be described later. The temperature is a predetermined temperature required to form a print on the sheet.

The circuit conductor 4 is for supplying external power, a printing signal, and the like to the heating element 3 and the driver IC 6. For example, Al (aluminum) or Cu
It is made of a metal such as (copper), and is electrically connected to a wiring conductor 9 of an FPC 7 described later on one side of the upper surface of the ceramic substrate.

In the present embodiment, the plurality of circuit conductors 4 connect the common electrode 4a commonly connected to all the heating elements 3 and each heating element 3 and the output terminal of the driver IC 6 corresponding to the heating element 3. The common electrode 4a and the individual electrode 4b have an operation of applying power to the heating element 3, and the signal wiring 4c has an individual electrode 4b and a signal wiring 4c connected to the input terminal of the driver IC 6. It functions to supply an external printing signal, clock signal, latch signal, strobe signal, etc. to the driver IC 6.

Of these circuit conductors 4, one end is led out to one side of the upper surface of the ceramic substrate because of the common electrode 4a.
And the signal wiring 4c only, and a circuit terminal 5 is provided at a lead-out portion of each of the common electrode 4a and the signal wiring 4c. The individual electrodes 4b are formed in a region between the heating element row and the driver IC 6, and these individual electrodes 4b are not led out to one side of the upper surface of the ceramic substrate.

The heating element 3 and the circuit conductor 4 are
By adopting a conventionally known thin film technique, specifically, a sputtering method, a photolithography technique, an etching technique, or the like, the ceramic substrate 2 is adhered and formed so as to have a predetermined pattern and a predetermined thickness on the upper surface of the ceramic substrate 2.

The driver IC 6 has a plurality of output terminals and input terminals, a driving circuit such as a switching element, a logic circuit such as an AND gate, a latch circuit, a shift register, and the like on its lower surface. In addition, the operation of individually controlling the energization of the heating elements 3 based on the print signal or the like input from the input terminal is performed.

The output terminal of the driver IC 6 is connected to the corresponding individual electrode 4b, and the input terminal 4c is connected to the corresponding signal wiring 4c.
Are electrically connected to each other through a conductive adhesive such as solder.

On the other hand, a part of the FPC 7 is superimposed on one side of the ceramic substrate 2 on which the circuit terminals 4 are juxtaposed.

The FPC 7 has a wiring conductor 9 made of metal such as copper sandwiched between a base film 8a and a cover film 8b made of a polyimide resin having a thickness of, for example, 10 to 35 μm. Has a structure in which a wiring terminal 10 is juxtaposed at one end of a wiring conductor 9 led to a superimposed portion of the wiring conductor 9.
The FPC 7 and the head substrate 1 are electrically connected by soldering 10 to the corresponding circuit terminals 4.

The FPC 7 connects the head substrate 1 to the printer main body, and outputs electric power and printing signals from the outside (printer main body and the like) to the heating element 3 and the driver I on the head substrate 1.
A connector (not shown) for connecting the thermal head to the printer body is attached to the rear end of the printer.

The wiring terminal 10 of the FPC 7 and the head substrate
First, the front end of the FPC 7 on which the wiring terminals 10 are arranged side by side is overlapped along one side of the ceramic substrate 1 on which the circuit terminals 5 are arranged side by side. Solder 11 is interposed between 5 and 10,
Is heated and melted by a heater bar or the like.

The circuit terminal 4 located at both ends of the plurality of circuit terminals 4 and the wiring terminal 10 soldered to the circuit terminal 4 are both connected to the circuit terminal 4 and the wiring terminal 10.
There are slits 5a, 10a oriented in a direction perpendicular to the direction in which the FPCs are arranged. Further, holes 7a are formed in the base film 8a of the FPC 7 located on these slits 5a, 10a. In the present embodiment, a part of the common electrode 4a among the three types of circuit conductors 4 described above is led out to both ends in the longitudinal direction of the ceramic substrate 2, and the circuit terminals provided on the lead-out portions are provided.
5, 5 are provided with slits 5a, 5a.

The hole 7a functions as a viewing window for positioning the FPC 7 with respect to the head substrate 1 when the FPC 7 is connected to the head substrate 1 and assembling the thermal head. Substrate 1 and FPC7
And combines the function of a resin material inlet for favorably introduced between the width W ₁ of the hole portion 7a as by 10% to 30% narrower than the width W ₂ of the slit 5a of the circuit terminal 5 is there. For example, when the width of the slit 5a is 1.0 mm,
The width of the hole 7a is set to 0.7 mm to 0.9 mm.

For this reason, when assembling the thermal head, when positioning the FPC 7 with respect to the head substrate 1 visually, it is necessary to set the position of the FPC 7 while confirming the pattern and the like on the upper surface of the head substrate through the hole 7a. it can. Specifically, when the inside of the hole 7a is viewed with a binocular microscope or the like, the FPC is so arranged that the contour of the slit 5a is located outside the hole 7a and the circuit terminal 5a is completely invisible.
By setting the position of 7, the FPC 7 can be accurately and easily positioned with respect to the head substrate 1. Therefore F
The PC 7 can be positioned in a relatively short time, and the productivity of the thermal head can be improved.

A resin material 12 is introduced between the head substrate 1 and the FPC 7 through a hole 7a, and the introduced resin material 12 is transferred to the upper surface of the head substrate 1, the upper surface of the FPC 7 and the surface of the solder 11. To be adhered to.

The resin material 12 is made of a silicone resin, an epoxy resin, or the like, and functions as a reinforcing member for reinforcing the connection portion between the head substrate 1 and the FPC 7 at both ends thereof. , The upper surface of the FPC 7 and the surface of the solder 11, so that the connection can be firmly protected and reinforced.
Therefore, with the use of the thermal head, etc., the head substrate 1
When the temperature of the FPC 7 becomes relatively high, the solder joint can be effectively prevented from being damaged even if thermal stress caused by the difference in the thermal expansion coefficient between the two is repeatedly applied. Reliability is also improved.

The resin material 12 is usually 12V to 24V.
And has a function of effectively protecting the common electrode 4a and the like held at the potential of the common electrode 4a and effectively preventing the common electrode 4a and the like from being oxidized and corroded.

The slits 5a of the circuit terminals 5 are formed at the same time as the circuit conductors 4 by masking and etching the necessary portions using a photoresist when forming the circuit conductors 4 in a predetermined pattern. Wiring terminal
When the wiring conductor 9 is formed, the ten slits 10a are formed simultaneously with the wiring conductor 9 by the same method as the slit 5a. The hole 7a of the FPC 7 is formed at a predetermined location by a conventionally known punching process or the like.

The resin material 12 is formed between the head substrate 1 and the FPC 7 through the hole 7a by, for example, applying a liquid silicone resin precursor such that a part thereof is also adhered to the upper surface of the FPC 7. By injecting and natural curing, it is formed in a state of being adhered to the upper surface of the head substrate 1, the upper surface of the FPC 7, and the surface of the solder 11. The introduction of the liquid precursor into the hole 7a is performed using a dispenser or the like, and the viscosity of the liquid precursor used at this time is 30 poises or less.
It is preferable to set it within the range of 80 poise.

Thus, in the above-described thermal head, external power, printing signals, and the like are supplied to the heating element 3 and the driver I through the wiring conductor 9 of the FPC 7 and the circuit conductor 4 of the head substrate 1.
C6 to cause the heating elements 3 to individually and selectively generate Joule heat with the driving of the driver IC 6;
The generated heat is conducted to the recording medium, and a predetermined print is formed on the recording medium to function as a thermal head.

It should be noted 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.

[0036]

According to the thermal head of the present invention, the circuit terminals on both ends of the circuit terminals on the head substrate and the wiring terminals of the FPC which are soldered to the circuit terminals are arranged in the same direction. A slit is provided in a direction perpendicular to the slit, and a resin material introduced between the ceramic substrate and the FPC is attached to the upper surface of the head substrate, the upper surface of the FPC, and the surface of the solder through a hole formed in the FPC positioned on the slit. Therefore, when visually aligning the FPC with the head substrate when assembling the thermal head, the position of the FPC can be set while checking the pattern on the upper surface of the head substrate through the holes. Therefore, F
It is possible to improve the productivity of the thermal head by aligning the PC in a relatively short time.

In the thermal head of the present invention,
Make the hole of the FPC 10% to 3% smaller than the slit width of the circuit terminal.
By making the width narrow by 0%, when looking into the hole at the time of the above-described alignment, the outline of the slit is located outside the hole and the circuit terminal is completely invisible.
By setting the position, the FPC can be accurately and easily positioned with respect to the head substrate. Therefore, the FPC can be positioned in a shorter time.

Further, in the thermal head of the present invention,
Since the resin material introduced between the head substrate and the FPC through the holes is well adhered to the upper surface of the head substrate, the upper surface of the FPC, and the surface of the solder, respectively, the connection portion is strongly protected and reinforced. be able to. Therefore, when the temperature of the head substrate and the FPC becomes relatively high due to the use of the thermal head and the like, even if the thermal stress caused by the difference in the thermal expansion coefficient between the two is repeatedly applied, the solder joint is not damaged. This can be effectively prevented, thereby improving the reliability of the thermal head.

[Brief description of the drawings]

FIG. 1 is a plan view of a thermal head according to one embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a sectional view taken along line XX of FIG. 1;

FIG. 4 is a sectional view taken along line YY of FIG. 1;

[Explanation of symbols]

1 ... head substrate, 2 ... ceramic substrate, 3 ...
・ Heating element, 4 ・ ・ ・ Circuit conductor, 5 ・ ・ ・ Circuit terminal, 5a
... Slit of circuit terminal, 6 ... Driver IC,
7 ... flexible wiring board (FPC), 7a ... hole, 8a ... base film of FPC, 8b ... FPC
Cover film, 9 ... wiring conductor, 10 ... wiring terminal, 10a ... wiring terminal slit, 11 ... solder, 12
... Resin materials

Claims (3)

[Claims] 1. A plurality of heating elements and a plurality of circuit conductors which are linearly arranged on a square ceramic substrate, and at least one end of each of the circuit conductors is attached to one side of the upper surface of the ceramic substrate. A head substrate having a plurality of circuit terminals juxtaposed on the derivation portion, and a part superimposed along one side of a ceramic substrate having the circuit terminals juxtaposed, and soldered to the circuit terminal at the overlap portion. A flexible wiring board having a plurality of wiring terminals arranged side by side, wherein both the circuit terminals located at both ends of the plurality of circuit terminals and the wiring terminals soldered to the circuit terminals are provided. A slit is provided in a direction perpendicular to the direction in which the terminals are arranged, and the head substrate and the flexure are formed through holes formed in the flexible wiring substrate located on the slit. The upper surface of the head substrate the introduced resin material between reluctant wiring board, a thermal head is characterized by comprising by deposited on the upper surface and the solder surface of the flexible wiring board. 2. The thermal head according to claim 1, wherein the circuit terminal provided with the slit is connected to all the heating elements in common. 3. The thermal head according to claim 1, wherein the hole of the flexible wiring board is narrower by 10% to 30% than the slit width of the circuit terminal.