JPH01269560A - Thermal head - Google Patents

Abstract

PURPOSE:To improve electrical connection between terminals while preventing the generation of warpage even at a high temperature by bonding and unifying a section between the external output terminal of a ceramic substrate and the terminal of an FPC circuit by an anisotropic conductive film and fixing the FPC circuit to a heat sink. CONSTITUTION:The direction of the electrical continuity of an anisotropic conductive film 1 is set so as to conduct sections among both terminals of the external output terminals 4 of a ceramic substrate 2 and the terminals 6 of an FPC circuit 5. The film 1 is mounted in such a manner that the film 1 is inserted among the external output terminals 4 of one end of the substrate 2 and the terminals 6 of the FPC circuit 5, heated, pressed and unified. The joined substrate 2 and FPC circuit 5 are fixed to a heat sink 8 by screws 10 through the mounting holes of the FPC circuit 5. Accordingly, excellent electrical connection among the terminals is acquired, and the substrate 2 is supported freely to the heat sink even when the substrate 2 is heat-generated and a thermal head is brought to the state of a high temperature, thus generating no warpage due to heat, then obtaining the uniform quality of printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a thermal head used for printing on thermal recording paper.

[Conventional technology]

Thermal heads are configured to print numbers, letters, symbols, etc. on thermal recording paper by applying electricity to a resistor mounted on an insulating substrate such as ceramic, which generates heat to print numbers, letters, symbols, etc. on heat-sensitive recording paper. There is a strong demand for sex.

A conventionally used thermal head will be explained with reference to FIGS. 4 to 6. Fig. 4 is a perspective view of the thermal head, and Fig. 5 is an explanatory view showing only the (5) part (21, which will be described later in Fig. 4). A thick film molded by or a thin film resistor (3) molded by sputtering is mounted on the left end, and a flexible printed circuit (5) (hereinafter referred to as FPC circuit), which will be described later, has a board signal line (not shown) on the left end. ) has external output terminals (4) that are grouped together for easy connection.(5) is an FPC circuit that transmits power, signals, etc. input to the connector (to) described later to the ceramic substrate (2). , has a terminal (6) on the end face for electrical connection with the ceramic substrate (2), and is made of a thin glass epoxy plate, etc. (7) is a member that reinforces the FPC circuit (5), and is made of glass, for example. It has an end face (7a) that is sheared or cut with a reinforcing plate made of epoxy board.(8) radiates the heat generated by the resistor (3), and also connects the ceramic substrate (2), FPC circuit (5) and reinforcement. Heat sink supporting board (7), (9) is external output terminal (4) and FPC circuit (5)
This is a press-contact plate for reducing contact resistance and uniformly press-contacting the terminal (6) of the terminal (6) to obtain a good electrical connection.It is made of, for example, an aluminum plate, and is connected to the heat sink (8) by a plurality of screws Q□.
It is firmly tightened. @ is for absorbing irregularities due to the mechanical dimensional accuracy of the aluminum pressure contact plate (9) and bringing them into contact with uniform pressure to avoid damaging the external output terminals (4) and terminals (6). It is adhered or held to the pressure contact plate (9) with pressure contact rubber. (A) is a connector for an electric circuit when the thermal head (100) is attached to and operated in a device such as a facsimile or a printer. Figure 6 shows the ceramic substrate (2) shown in Figure 5.
The external output terminal (4) of the FPC circuit (5) and the terminal (6) of the FPC circuit (5)
) is a diagram showing a press-contact state.

Next, the operation will be explained.

Thermal head (legs are installed on the facsimile or printer body (not shown) and connected via connector 0!9 t=
[fJW Ha, F P C circuit (51, i child (61,
The external output terminal (4) and the ceramic substrate (2) (not shown) pass through the integrated circuit and the substrate signal line,
) is locally heated. On the other hand, on the thermal paper that moves continuously between the thermal head (9) and a buffet (not shown), one number is printed by the locally heated resistor (3).

Symbols, etc. are recorded thermally.

[Problem to be solved by the invention]

Since the conventional thermal head is configured as described above, it has the following problems.

That is, as shown in Fig. 7, when assembling the thermal head α (b), it is necessary to remove small dust and glass epoxy reinforcing plate (7).
) Foreign matter such as glass fiber particles attached to the end face (7a) of the external output terminal (4) and the terminal (6) often get into the space between the external output terminal (4) and the terminal (6), and are pressed together in that state. In the case of Jin, it is almost impossible to detect by visual inspection, and in the worst case, there may be a poor electrical circuit connection or a disconnection between the external output terminal (4) and terminal (6) during the final shipping test or during product operation. l
There was a problem in that the cause could be determined from ζ. Eliminating this foreign matter (2) such as dust and dirt is a capital investment! It requires an amount of $$ and is practically impossible.

In addition, since it is necessary to make a uniform electrical connection between the external output terminal (4) and the terminal (6) with as little contact resistance as possible, a pressure contact plate (9) made of aluminum or the like is required.
) is also strongly tightened to the heat sink (81) made of aluminum or the like with multiple screws, so the entire thermal head (2) is mechanically rigidly assembled and attached to the printer stop. Substrate (2
) generates heat and reaches a steady state, the entire thermal head (chestnut) becomes high temperature, and the ceramic substrate (2) that is the component and the F
PC circuit (5), reinforcing plate (7).

The thermal head (9) is thermally deformed and warped due to the difference in coefficient of thermal expansion caused by the different materials of the heat sink (8) and the pressure contact plate (9). This warpage has caused a serious problem in that the thermal paper cannot be heated evenly, resulting in a decrease in the quality of recorded images.

This invention was made to solve the above-mentioned problems, and not only can a good drowsy connection be made between the terminals, but also
To obtain a thermal head device that does not warp even at high temperatures.

[Means for Solving the Problems] A thermal head according to the present invention includes a ceramic substrate provided with a resistor that has an external output terminal and generates heat when energized;
An FPC circuit that has terminals on the end face and transmits force and signals to the resistor on the ceramic substrate; and a reinforcing plate that mechanically reinforces the FPC circuit; and a heat sink supporting a reinforcing plate, an external output terminal of the ceramic substrate and a terminal of an FPC circuit arranged to face each other, and an anisotropic conductive wt film inserted between the opposing faces, the ceramic board It is bonded and integrated with FPC circuit and FPC circuit by heating and pressurizing.
Moreover, the FPC circuit is configured to be fixed to a heat sink.

[For production]

In the thermal head according to the present invention, the external output terminal of the ceramic substrate and the terminals of 110 circuits are bonded and integrated by an anisotropic conductive film, and 110 circuits of the integrated circuit are fixed to a heat sink, so that a good connection between the terminals is achieved. Electrical connection is established, and even if the ceramic substrate generates heat and the thermal head reaches a high temperature, the ceramic substrate is freely supported against the heat sink, so warping due to heat does not occur and uniform printing quality is maintained. can get.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Components that are the same as those in the conventional example are denoted by the same reference numerals, and therefore the description thereof will be omitted.

In Fig. 1, (1) is an anisotropic conductive film, which is commercially available under the trade name of Hitachi Chemical's (lead-made anisolum) or Nitto Denko's (lead-made anisotropic conductive film), and is covered with an adhesive described later. The electrical conduction directions of this anisotropic conductive film (1) are X and Y.

The first method of the present invention has characteristics in only one of the three z directions.
In the figure, the external output terminal (
4) and the terminal (6) of the 110 circuit (5). To attach the anisotropic conductive film (1), insert it between the external output terminal (4) provided at one end of the ceramic substrate (2) and the terminal (6) of the 110 circuit (5), and heat the film at 150°C to It is heated to about 200°C and pressure is applied.At this time, the conductive 5 (not shown) such as carbon, nickel, gold, or silver present in the anisotropic conductor 1 (11) is crushed and the electric current between the two terminals is Continuity is established.

Note that the width (c) of the electrically conductive portion formed by this conductive filler is as shown in FIG.
It is sufficiently larger than the wire width of the external output terminal (4), which is not shown in the figure, and the conductive 5 is covered with thermosetting or thermoplastic adhesive, so the ceramic substrate (2)
and 110 circuit (5) are joined and integrated with this adhesive. In this way, the ceramic substrate (21) and the RPC circuit (5), which are electrically and mechanically bonded to each other by the anisotropic conductive film (1), are connected to the mounting hole (not shown) provided in the 110 circuit (5). ) and screw Ql through the heat sink (8
) is fixed.

In the thermal head 0 (b) as shown in Figure 3, there is no dust or dirt on the end surface (7a) of the Gauss epoxy reinforcing plate (7) between the external output terminal (4) and the terminal (6). Even if there is a foreign substance (9) such as Paris attached, the anisotropic conductive film (11) will wrap around the foreign substance (2) and the cushion and '
Thus, electrical connection between the terminals (4) and (6) can be established. Also, this foreign object (2) is extremely thin and the third
Even if it exists completely in the cross section shown in the figure,
As shown in Figure 2, the electrically conductive part width ω) is connected to the terminal (4).
Since it is sufficiently wider than the width of (6), the electrical connection will not be impaired.

Furthermore, even if there is a foreign object (2) covering the width (c) of the electrically conductive part shown in FIG. 2, it can be visually discovered, so it will be removed and assembled. Furthermore, the external output terminal (4) of the ceramic substrate (2) and the terminal (6) of the 110 circuit (51) have low contact resistance and uniform electrical connection by heating and pressurizing the anisotropic conductive film (1). Therefore, there is no need to pressure-weld the terminals with a temporary pressure-welding method as in the conventional example, and only the self-weight support is required for attachment to the heat sink (8).Furthermore, it is mechanically integrated. Ceramic board (2) and 110 circuit (
5) is fixed to the heat sink (8) with the screw Ql through the hole provided in the 110 circuit (5), so the ceramic substrate (2) is freely supported relative to the heat sink (8). Even if the ceramic substrate (2) generates heat and the thermal head (9) enters a high-temperature steady state, no thermal deformation due to thermal expansion occurs in the ceramic substrate (2), and uniform printing quality can be obtained. In the standing embodiment, the heat sink (8) is attached to the heat sink (8) using screws α, but it can also be mounted using rivets, adhesives, or metal fittings that hold the 110 circuit (5) to the heat sink (8). The same effects as in the embodiment are achieved.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a ceramic substrate having an external output terminal and a resistor that generates heat when energized, a 110 circuit that transmits power and signals to the ceramic substrate and has terminals on the end face, and this FPC circuit. a reinforcing plate that mechanically reinforces the ceramic substrate; a heat sink that radiates heat generated by the ceramic substrate and supports the ceramic substrate, the FPC circuit, and the reinforcing plate; and an external output terminal of the ceramic substrate.
The FPC circuit is equipped with an anisotropic conductive film inserted between opposing terminals of the PC circuit, and is bonded and integrated with the ceramic substrate and the RPC circuit by heating and pressurizing, and the FPC circuit is fixed to the heat sink. A stable and good electrical connection can be obtained, and the ceramic substrate will not warp when the thermal head reaches a high temperature, resulting in inexpensive and uniform printing quality.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a perspective view showing a thermal head according to an embodiment of the present invention, FIG. 2 is a view showing an electrical connection part of a terminal of the present invention, and FIG. 3 is a cross-sectional view thereof. It is. 4 to 7 show a conventional thermal head. FIG. 4 is a perspective view, FIG. 5 is an explanatory view showing only the terminal portion of FIG. 4, and FIGS. 6 and 7 are terminals. FIG. 3 is a diagram showing the electrical connection state of (1
1 is an anisotropic conductive film, (2) is a ceramic substrate, (4) external output terminal, (5) is an FPC circuit, (6) is a terminal, (8
) is a heat sink. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] a ceramic substrate having an external output terminal and provided with a resistor that generates heat when energized; a flexible printed circuit having a terminal facing the external output terminal and transmitting power and signals to the resistor of the ceramic substrate; a reinforcing plate for reinforcing the printed circuit; a heat sink for dissipating heat generated by the ceramic substrate and supporting the ceramic substrate, the flexible printed circuit, and the reinforcing plate; and a space between an external output terminal of the ceramic substrate and a terminal of the flexible printed circuit and facing each other; an anisotropic conductive film disposed on the anisotropic conductive film, the ceramic substrate and the flexible printed circuit are integrated by heating and pressurizing the anisotropic conductive film, and electrical connection between both terminals is obtained; A thermal head characterized in that a flexible printed circuit is fixed to the heat sink.