JP2582999Y2 - Thermal head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head. More specifically, according to the present invention, a heating substrate (a ceramic substrate serving as a thermal head body) on which a metal electrode film of a thermal head, a heating element, and a driver IC for driving the same are mounted, and a signal for controlling the energization of the driver IC are input. And a signal input circuit board for bonding the signal input circuit board.

[0002]

2. Description of the Related Art Conventionally, connection between a heat generating substrate 101 and a flexible printed wiring board (hereinafter referred to as FPC) 102 for signal input in a thermal head is generally performed by a pressure contact method as shown in FIG. In this pressure contact method, the terminal 104 exposed from the coverlay (insulating protective layer) 103 is used.
The FPC 102 having a portion plated with gold 105 is overlaid on the terminal 106 of the heat generating substrate 101, and is pressed from above with a cover 108 via a silicon rubber 107 or the like to be electrically connected.

[0003] In rare cases, as shown in FIG.
In some cases, the terminal 104 of No. 02 and the terminal 106 of the heat generating substrate 101 are joined by solder plating 201. in this case,
The solder plating 201 is formed on the terminals 104 of the FPC 102 in advance by plating. And F
In a state where the PC 102 and the heat generating substrate 101 are overlapped, the FPC
A heated bar-shaped soldering iron is pressed from above 102 and the solder plating 201 is melted to join.

In each case, the terminal 1 on the side of the heat generating substrate 101
In many cases, the Au electrode is used alone.

[0005]

However, in the case of the pressure contact method, the heating substrate 101 to be connected and the FPC
A silicon rubber 107 and a cover 108 are required in addition to 102, and the number of parts increases. In addition, when an external force is applied, the FPC 102 may come off. In addition, when the solder bonding method is adopted to reduce the number of components, if the terminal portion on the side of the heat generating substrate 101 is a film of Au alone, regardless of the thickness or the thickness, Au is eroded at the solder bonding portion. In addition, it is easy to make bonding impossible, which lowers the yield of the thermal head. To avoid this, strict control of the bonding conditions is required.

Therefore, the present invention provides a thermal head
It is an object of the present invention to provide a thermal head having a high yield, in which a heat generating substrate and a signal input circuit substrate can be easily joined by solder.

[0007]

To achieve Means for Solving the Problems] Such object, the present invention is, in a thermal head signal input circuit board attached to the substrate metal of the electrode film is formed, one that the A g-Pd So that the part overlaps the electrode film
Deposition directly on the plate, and directly on the substrate on this Ag-Pd film
The signal input circuit board is solder-bonded to the portion thus formed. Here, so that good Mashiku is provided with a protective layer to the overlapping portion of the electrode film and the Ag-Pd film.

[0008]

[Operation] Therefore, the part to be soldered is made of Au or the like.
Since there is no terminal of the electrode film thus formed, erosion by solder can be prevented. In addition, since the Ag-Pd film and the solder are very familiar and have high bonding strength, the heat generating substrate and the signal input circuit substrate are firmly soldered.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings. This embodiment is applied to an end face type thermal head.

FIG. 1 shows an example of a schematic structure of an end face type thermal head to which the present invention is applied. This thermal head is
A heat-generating substrate 1 on which a heat-generating element 5 and electronic components such as a driver IC 6 for driving the heat-generating element 5 are mounted; a heat-radiating plate 2 for supporting and reinforcing the heat-generating substrate 1; and electronic components such as a driver IC 6 covered on the heat-generating substrate 1 Head cover 3 for protection
And a flexible printed wiring board (hereinafter abbreviated as FPC) 4 forming a signal input circuit board for inputting a signal for controlling the energization of the driver IC 6.

As shown in FIG. 4, the heating substrate 1 is usually formed on a ceramic substrate (insulating substrate) 10 with an underglaze 11 as a heat insulating layer and a heating resistor as a heating element (not shown). And a wiring electrode 12 (including the terminal 14) made of a metal electrode film and an overglaze 13 as a protective layer are laminated. The wiring electrode 12 is, for example, as shown in FIG.
Individual electrodes and a portion constituting the common electrode, terminal portions of the signal for input to Ru is drawn from driver IC6 (of the wiring electrode terminals for connecting the end surface heating element 5 and the driver IC6 formed electrically The part is designated in particular by the reference numeral 14). The wiring electrode 12 including the terminal 14 is usually formed on the underglaze 11 using a thick or thin Au (gold) film. For example,
It is obtained by applying a paste of Au in a desired pattern on the underglaze 11 by a thick film printing technique and baking this. As shown in FIG. 3, silver-palladium (Ag-Pd)
Is formed. For example, an Ag-Pd-based alloy paste is applied on the terminals 14 by a thick-film printing technique, and is baked to obtain an Ag-Pd film 15. In addition, FPC4
The Ag-Pd film 15 in a portion where is not soldered is covered with an overglaze 13. Overglaze 13
Usually, silicon oxide (SiO ₂ ) or the like is employed, and the film is formed by a thick film printing technique or the like. Note that the driver IC 6 is sealed with a sealing resin 9.

The FPC 4 excludes, for example, a base film 20 having flexibility, a wiring circuit (including a terminal portion 21t) 21 formed thereon with a conductive material such as copper (Cu), and a terminal portion 21t. And an insulating cover lay 22 for protecting the wiring circuit 21. Solder plating 23 is provided on the surface of the terminal portion 21t connected to the terminal 14 on the heat generating substrate 1 side of the FPC 4. The solder plating 23 is solder that is film-formed by a plating process. A connector 7 for inputting a control signal is soldered to the other end of the FPC 4 with a reinforcing plate 8 for protecting the FPC 4 interposed therebetween, and other circuit components are mounted as necessary. .

Heating substrate 1 and FP configured as described above
The connection with C4 is performed by overlapping and soldering the terminal portion 21t of the FPC 4 on the Ag-Pd film 15 of the terminal 14 on the heat generating substrate 1 side. The soldering is performed by aligning the terminals 14 of the heat-generating substrate 1 with the corresponding terminal portions 21t of the FPC 4 and then applying a bar-shaped soldering iron (not shown) from above the FPC 4 to form a solder plating 23.
It is carried out by the the melt-score. The molten solder is made of the Ag-Pd film 15 of the heat generating substrate 1 and the terminal portion 21t of the FPC 4.
And join. The terminal 14 made of an electrode film of the substrate on which the metal electrode film is formed, that is, the electrode film of the heat generating substrate 1 is covered with the Ag-Pd film 15 at the portion to be soldered. Further, since the Ag-Pd film 15 and the solder are very familiar and have high bonding strength, the heat generating substrate 1 and the signal input circuit substrate 4 are firmly soldered.

FIGS. 5 to 7 show a second embodiment. In this embodiment, the Ag-Pd film 15 is formed directly on the ceramic substrate 10 or the underglaze 11, and only a part of the Ag-Pd film is superimposed on the terminal 14. That is,
As shown in FIG. 5, the terminal 14 is formed shorter than in the case of the first embodiment, and the Ag-Pd film 15 partially overlaps the terminal 14 so that the ceramic substrate 10 (or the underglaze 11) is formed. A film is formed thereon (see FIG. 6).

Further, as shown in FIG. 7, the Ag-Pd film 15 formed on the terminal portion 21t of the FPC 4 and the terminal 14 not to be soldered is preferably covered with an overglaze 13. The overglaze 13 is made of silicon oxide (SiO ₂ ) or the like.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in this embodiment, gold (Au) is used as the material of the electrode, but the same effect can be obtained by using silver, nickel, aluminum or the like. Although the signal input substrate is a flexible printed wiring board (FPC), the same effect can be obtained by using a general substrate made of bakelite, epoxy resin, or the like.

[0017]

As is apparent from the above description, the thermal head of the present invention has a substrate on which a metal electrode film is formed,
That the terminal comprising a heating substrate of the electrode film was coated with Ag-Pd film, since to carry out solder bonding of the FPC thereon, and a solder pin and Ag-Pd film and Ag-Pd film Each fits very well and is firmly joined to each other.

In the present invention, when the Ag-Pd film is formed directly on the substrate so that a part of the Ag-Pd film overlaps with the terminal, the terminal of the electrode film made of Au or the like does not exist in the portion where the soldering is performed. In addition, there is no danger of the electrode film, especially the Au electrode film being eroded by the solder, and the highly reliable solder bonding can be performed.

Further, when a portion where the terminal and the Ag-Pd film partially overlap is covered with a protective layer such as overglazing, the bonding between the terminal and the Ag-Pd film is very stable, and a highly reliable solder joint is obtained. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a thermal head of the present invention.

FIG. 2 is a front view showing an example of a wiring electrode of a heat generating substrate.

FIG. 3 is a front view showing an example in which an Ag-Pd film is formed on a terminal portion of the heat generating substrate of FIG.

FIG. 4 is an enlarged cross-sectional view of a bonding portion illustrating a state where the heat generating substrate and the FPC of FIG. 3 are connected.

FIG. 5 is a front view of a terminal portion of a heat generating board according to a second embodiment of the present invention.

FIG. 6 is a front view showing a state where an Ag-Pd film is formed on a terminal portion of FIG. 5;

FIG. 7 is a diagram related to a third embodiment of the present invention, and is an enlarged cross-sectional view of a joint portion illustrating a state where the heat generating substrate and the FPC are connected.

FIG. 8 is an enlarged cross-sectional view of a bonding portion illustrating a connection state between a heat generating substrate and an FPC by a conventional pressure contact method.

FIG. 9 is an enlarged cross-sectional view of a bonding portion for explaining a connection state between a heat generating substrate and an FPC by conventional solder bonding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heat generation board 4 Flexible printed wiring board (signal input circuit board) 10 Ceramics substrate 11 Underglaze 12 Metallic electrode film 13 Overglaze (protective layer) 15 Ag-Pd film 23 Solder plating

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-309468 (JP, A) JP-A-60-193664 (JP, A) JP-A-4-22244 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) B41J 2/335

Claims (2)

(57) [Scope of request for utility model registration] 1. A thermal head metal electrode film signal input circuit board substrate formed is attached, so that a part of the A g-Pd is superposed on the electrode film
Is formed directly on the substrate, and the substrate on the Ag-Pd film is formed .
A thermal head, wherein the signal input circuit board is soldered to a portion directly formed on a plate . 2. An overlap between the electrode film and the Ag-Pd film.
2. The device according to claim 1, wherein a protective layer is provided on the portion.
Thermal head.