JPH0443052A - Thermal head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal head used in printers, facsimile machines, etc., and in particular to a driving semiconductor integrated circuit device (hereinafter referred to as "driving semiconductor integrated circuit device") on a substrate on which a heat generating part is formed.

This relates to a direct drive type thermal head equipped with a drive IC (referred to as a drive IC).

(Prior art) A heating element is formed on a substrate such as a ceramic substrate by a thick film method or a thin film method, but regardless of whether it is a thick film method or a thin film method, two heating elements are formed on the substrate. , and a wiring board having a connector and input wiring for distributing input signals input from the outside to the driving IC and supplying power are formed as separate boards.

FIG. 3 shows an example of this, in which a heating element 42 is formed on a ceramic substrate 40, and a driving IC 4 is formed on the ceramic substrate 40.
4 (sealed with resin) is mounted, and output wiring connecting the heating element 42 and the driving IC 44 is also formed on the substrate 40. On the other hand, an input wiring board 46 different from the board 40 is formed of, for example, a flexible printed wiring board,
The input wiring to the drive IC 44 on the board 40 and the wiring on the input wiring board 46 are aligned on the support plate 48,
They are connected by pressure contact with a pressure contact reinforcing plate 52 via a pressure contact rubber 50 and a pressure contact screw 54 .

FIG. 4 shows another example, in which a ceramic substrate 56 on which a heating element 58 is formed and an input wiring board 60 are aligned and bonded on a support plate 62, and the input wiring board 60 is bonded. The drive IC 64 is mounted, and the output wiring on the board 56 and the drive IC 64 are connected by wire bonding, and the input wiring on the input wiring board 60 and the drive IC 64 are also connected by wire bonding. There is.

(Problems to be Solved by the Invention) The thermal head shown in FIG. 3 requires a technique for accurately pressing and connecting the heat generating board 4o and the input wiring board 46, and also requires a connection process. For example, 12 dots/m
In a high-density thermal head of more than m, it is technically difficult to press the input wiring board 46 to the heat generating board 40 from the viewpoint of accuracy.

In addition, extra members such as the pressure welding reinforcing plate 52, screws 54, and pressure welding rubber 50 are required for pressure welding, which not only increases cost and assembly man-hours, but also affects the flatness of the thermal head itself depending on the tightening force of the screws 54. There are also problems in terms of quality, such as the impact on

In the thermal head shown in FIG. 4, the wiring of the input wiring board 60 is plated with gold to connect the wiring of the input wiring board 60 and the driving IC 64, and the input wiring board 60 is made of high density.
It is necessary to make the through holes smaller, which increases costs. Furthermore, when the board 56 and the input wiring board 6o are bonded to the support plate 62, the difference in thermal expansion coefficient due to the different materials of the three members 56, 60, 62 may cause quality problems such as loss of flatness due to temperature changes. A problem occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal head that can solve the problems of quality, high cost, and a large number of man-hours due to the heat generating board and input wiring board being separate boards. It is something to do.

(Means for Solving the Problems) In the present invention, an input section for inputting signals and power from the outside is provided on a substrate on which a heat generating section is formed, and a driving IC is mounted on the substrate. Further, wiring such as input wiring connecting the input section and the driving IC and output wiring connecting the driving IC and the heat generating section are arranged, and the input wiring has a two-layer structure, and the input wiring connects the driving IC to the driving IC. The first layer wiring and the output wiring are thin film wiring. For example, aluminum or gold can be used as the material for the thin film wiring. Gold is preferable when it is necessary to plate the output wiring.

The second layer wiring of the input wiring is a thick film wiring formed by thick film printing or a thin film wiring formed by a thin film process, and in a preferred embodiment, the second layer wiring of the input wiring is a thick film wiring.

(Function) The input wiring and the input part are also integrally formed on the heating board on which the heating part is formed, and the drive IC is also mounted on the heating board, so the heating board and input wiring are connected to each other as in the past. This eliminates the need for assembling the heat-generating board and input wiring board by bonding the board onto a support plate or by pressure bonding, reducing assembly man-hours and lowering costs. Therefore, the flatness is not impaired even by temperature changes, and the quality is stable.

Since the first layer of the input wiring is a thin film wiring, the negative layer wiring and the output wiring can be formed in the same process.

Further, thin film wiring can form finer patterns than thick film wiring.

(Embodiment) FIG. 1 is an external perspective view of one embodiment, and FIG. 2 is a schematic sectional view taken along line A-A in FIG. 1.

In FIG. 1, heating elements 4 formed by a thin film process are arranged in rows along one end of a ceramic substrate 2 whose surface is covered with a glassy glaze layer. An input pin 8 is connected to the other end of the board 2 by soldering, and is connected to a main body of a device such as a printer to receive input signals and power. 6 represents an input section including input pin 8. Reference numeral 10 denotes a drive section on which a drive IC is mounted and sealed with resin. A region 13 between the drive section 10 and the heating element 4 is an output section, and output wiring formed by a thin film process is formed therein. A common electrode 18 supplies driving power to the heating element 4, and is formed simultaneously with the output wiring by a thin film process, and is plated with copper to reinforce current capacity.

An input wiring section 12 is arranged between the drive section 10 and the input section 6 for distributing an input signal supplied from the input pin 8 to the drive IC of the drive section 10. The input wiring section 12 has a two-layer wiring structure, where the -th layer wiring is a thin film wiring formed at the same time as the output wiring of the output section 13, and the second layer wiring is a thick film wiring formed by a thick film printing method. be.

The structure of this embodiment will be explained in more detail with reference to FIG.

The substrate 2 has a structure in which the surface of an alumina ceramic substrate 2a is covered with a glassy glaze layer 2b. A resistor 20 is patterned and formed on the glaze layer 2b, and a common electrode 2, which is an electrode of a heating element, is formed on the resistor 20.
2 and an output wiring 24 which is a selection electrode are formed, and further,
A first layer wiring 26 of input wiring is formed. Resistor 2
0 is, for example, Ta5iO, 500 to 5 such as Ta, N, etc.
The electrodes 22, 24, and 26 are formed by patterning a film with a thickness of about 1 μm, for example.
Q film, or a thickness of e.g. 500 to enhance adhesion
A gold film with a thickness of, for example, about 1 μm formed through a Cr1ij or NiCr film is patterned. A portion 4 of the resistor 2o exposed between the electrodes 22 and 24 is a heating element, and the heating elements 4 are arranged in a direction perpendicular to the plane of the paper in FIG.

A protective film 28 is formed on the heating element 4 to protect the heating element 4 and to serve as an insulating film between the eyebrows of a two-layer wiring structure at the input section.

As the protective film 28, for example, a silicon nitride film (S13N4
) can be used, and its thickness is about 1 to 2 μm. If the protective film 28 is a silicon nitride film, fine bonding pads can be formed. Protective film 28
Other insulating films 1 such as glass may also be used. A hole is made in the protective film 28 to form a bonding pad on the output part [24], and a through hole is made in the input part to connect the first layer wiring 26 and the second layer wiring.

A second layer wiring 30 is formed on the protective film 28 at the input section by a thick film printing method. The material of the second layer wiring 30 is gold resinate (also called metal organic gold).
Ag or A can be used to reduce the cost.
g-Pd etc. can also be used. A protective film 32 is formed on the second layer wiring 30 by, for example, a thick film printing method. The protective film 32 is made of glass, for example.

In order to configure the driving section, the driving IC 34 is covered with a protective film 28.
The second layer wiring 3o of the input wiring is die-bonded on top.
are connected by wire bonding, and are also connected to output wiring 24 by wire bonding. 36 is a resin such as epoxy resin for sealing the driving IC 34.

The portion of the second layer wiring 30 exposed from the protective film 32 at the end of the substrate is a bonding pad for a connector, to which an input pin 8 as shown in FIG. 1 is connected by soldering.

Next, the manufacturing method of this example will be explained.

On the substrate 2, a resistor film of TaSi◯2, Ta, N, etc. is deposited over the entire surface by sputtering to a thickness of 500 to 5,000 layers. An electrode film is formed thereon by a vapor deposition method or a sputtering method. When using gold as an electrode film, gold has weak adhesion.

Approximately 500 adhesive layers such as Cr or NiCr are deposited, and a gold film of approximately 1 μm is formed thereon. When a gold film is used as an electrode, it becomes possible to plate the bonding pad portion and the current capacity reinforcing portion of the common electrode with copper or other metal.

However, if plating is not performed, aluminum or the like can be used in place of the gold electrode to reduce costs. After laminating the resistor film and the electrode film, they are patterned by photolithography and etching to form a common electrode 22, an output wiring 24 which is a selection electrode. The first layer wiring 26 of the input wiring and the resistor pattern 2o are formed. Since fine patterns can be formed using photolithography, complex patterns can be formed using this thin film process.

Next, a protective film 28 is formed. When a fine bonding pad is required, such as in flip-chip bonding, a silicon nitride film is used as a protective film that can be etched.
It is formed to a thickness of 1 to 2 μm using the D method or the like. Protective film 2
8 is patterned by photolithography and etching to form bonding pads and through holes for the input section.

As this etching, for example, plasma etching using CF4.02 and N2 as reactive gases can be used. If plating is necessary, apply plating to the bonding pad or common electrode.

The second layer wiring 30 is formed by a thick film printing method.

A protective film 32 made of glass or the like is formed on the second layer wiring 30 by a thick film printing method.

After that, W! The dynamic IC 34 is mounted by a wire bonding method or a flip chip method, and is sealed with a resin 36.

An input bin or a connector is connected to the input bonding pad of the second layer wiring 30.

(Effects of the Invention) In the present invention, the input wiring and the input section are also integrally formed with the heat generating board on which the heat generating section is formed.

Flatness is not impaired even by temperature changes, improving quality, and reducing assembly man-hours and lowering costs.

Moreover, it becomes easy to attach it to the equipment used.

Furthermore, since the output wiring is made of thin film wiring, the electrode material can be selected. For example, when plating the output wiring's bonding pads and common electrodes, it is preferable to use gold, which is easy to plate, and when not plating, low-cost aluminum can be used. Flexibility in material selection. There is.

Since the first layer of the input wiring is a thin film wiring, it can be formed at the same time as the output wiring. If the first layer of input wiring is thin film wiring and the second layer is thick film wiring, the thick film printing process only needs to be done once. Since the first layer of the input wiring is a thin film wiring, it becomes easy to form a fine pattern on the first layer of the input wiring.

[Brief explanation of the drawing]

Figure 1 is an external perspective view of one embodiment, and Figure 2 is A-A in Figure 1.
A schematic cross-sectional view taken along line A, and FIGS. 3 and 4 are cross-sectional views showing a conventional thermal head. 2...Substrate, 4...Heating element, 6...
...Input section, 8...Input pin, 10...
...Drive section, 12...Input wiring section, 13...
...Output section, 20...Resistor, 18...
...Common electrode, 24...Output wiring (selective electrode)
, 26... First layer wiring of input section, 28...
...Protective film, 30...Second layer wiring of input section, 3
4...Drive IC. Figure 1

Claims (2)

[Claims] (1) An input section for inputting signals and power from the outside is provided on the substrate on which the heat generating section is formed, and a driving semiconductor integrated circuit device is mounted, and the input section and the driving device are further mounted on the substrate. Wiring such as an input wiring for connecting the semiconductor integrated circuit device for driving and an output wiring for connecting the semiconductor integrated circuit device for driving and the heat generating section are arranged, and the input wiring has a two-layer structure. A thermal head in which the first layer wiring and the output wiring are thin film wiring. (2) The thermal head according to claim 1, wherein the second layer wiring of the input wiring is a thick film wiring.