JPS61263770A - Thermal head - Google Patents

Abstract

PURPOSE:To reduce the amount of a metal melted, facilitate setting pressing and heating conditions for an FPC and lower the possibility of electrical short- circuit failures, by providing a metallic layer comprising an easily solderable metal or an allow thereof having a melting point higher than that of a material used for a terminal part for external connection, on a conductor layer of a terminal part provided adjacently to a head surface. CONSTITUTION:A glaze layer 2 and a heating resistor layer 3 are provided in predetermined film thicknesses on an insulating substrate 1, and the conductor layer 4 is provided by vapor deposition of aluminum or an aluminum alloy. A conductive pattern of the layer 4 is provided by repeated masking, and an oxidation-resistant layer 6 and an abrasion-resistant layer 7 are provided in desired film thicknesses by sputtering. A conductive pattern of the layer 4 at the terminal part 11 is provided at the time of providing a conductive pattern on the head surface 12. Connection with the FPC for electrical connection with an external circuit is performed by soldering. At the terminal part, the metallic layer of an easily solderable metal or an alloy thereof having a melting point higher than that of the material used for terminal parts of the FPC is provided on the conductor layer.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thermal head, and more specifically, a plurality of heat generating resistor elements are linearly arranged on the same substrate, and the heat generating resistor elements are arranged in a straight line on the same substrate, and the heat generating resistor elements are arranged in a straight line on the same substrate. The present invention relates to a thermal head that generates heat by applying electricity to perform color recording on thermosensitive recording paper, or transfers and records onto plain paper via an ink ribbon.

[Prior art]

A conventional thermal head, for example, as shown in FIG.
A thin glaze layer 2 is provided on an electrically insulating alumina substrate 1, and on top of that a heating resistor layer 3 made of Ta, N, etc., which generates heat and gives coloring energy to a thermal recording paper (not shown) or the like; A conductor layer 4 connected to the heat generating resistor layer 3 and conducting current according to information, an oxidation-resistant layer 6 consisting of 8103 etc. and protecting the heat generating resistor layer 3 from deterioration due to oxidation, It is formed by sequentially laminating the heating resistor layer 3, the conductor layer 4, and the wear-resistant layer 7 for protecting the oxidation-resistant layer 6 from wear caused by contact with the heat-sensitive recording paper.

When a current is passed through the conductor layer 4, a part of the conductor layer 4 is removed, and a heat generating part 8 formed one step lower generates heat and gives color recording energy to the thermal recording paper or the like. . As shown in FIG. 8, the thermal head is provided with a common electrode line 9 and individual electrode lines lOa to 10g on both sides of the heat generating part 8. Both the common and individual electrode lines 9.10a to 10leg are connected to an external circuit (not shown) by soldering in the area of the lower terminal section 11 indicated by line B in the figure. When the conductor layer 4 is made of AI, a solder base layer in which Ni is vapor-deposited is generally formed on the conductor layer 4, and then the solder layer is covered with a solder dip. 1 in Figure 8
The upper head surface 12 other than the lower terminal portion 11 indicated by 1B is covered and protected by an oxidation-resistant layer 6 and a wear-resistant layer 7. Note that FIG. 7 is an enlarged sectional view taken along line AA' in FIG. 8.

[Conventional problems]

In such a conventional thermal head, the terminal portion 11
As described above, a solder layer is formed on the terminal portion 11, and a flexible printed circuit (FPC) that makes an electrical connection with an external circuit (not shown) is positioned, and the FP
Pressure and heat the solder layer on the C side and the solder layer on the terminal portion 11,
When welding, since both have the same melting point, they will melt almost at the same time, resulting in a large amount of solder.If the welding conditions are not strictly controlled, bridges will occur between each electrode line, causing electrical shorts. . Especially the terminal section 11 of the thermal head.
If the solder layer is formed by dipping molten solder, the surface tension of the solder will increase the variation in the thickness of the solder layer of each terminal part 11. Continuous operation tends to cause frequent bridges between each electrode line (terminal), making manufacturing control difficult and reducing yield. Furthermore, due to complete defects in the final manufacturing process, losses are large, which is a major drawback.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and its purpose is to prevent the occurrence of bridges between terminals when connecting an external circuit by adjusting the metal composition of the terminal portion connected to the conductor layer. An object of the present invention is to provide a thermal head with high manufacturing yield.

[Structure of the invention]

In order to achieve this object, the thermal head of the present invention provides a glaze layer on an insulating substrate, and laminates a heating resistor layer and a conductor layer thereon, so that the head surface that is pressed against the surface of the thermal recording paper is connected to the conductor. A part of the layer is removed and an oxidation-resistant layer and an abrasion-resistant layer are sequentially laminated, and a terminal portion connected to the head surface is formed on the conductor layer extending from the head surface from the outside. It is constructed by forming a metal layer made of an easily solderable metal or an alloy thereof, which has a melting point higher than that of the material used for the connection terminal portion of the connector.

The insulating substrate, the glaze layer, and the heating resistor layer are conventionally made of known materials, such as alumina for the insulating substrate.

Although glass can be used for the glaze layer and Tag N can be used for the heating resistor layer, it goes without saying that other materials having the same function as these materials can also be used. The film is formed to a predetermined thickness using

Further, the conductor layer is formed by vapor deposition of aluminum or an aluminum alloy to a predetermined thickness, but other materials having the same functions as these materials can also be used.

The NLt pattern of the conductor layer on the head surface is formed by two conventional masking repetitions using photolithography.

The oxidation-resistant layer and the wear-resistant layer can also be made of conventionally known materials, such as 3 i 0@ for the oxidation-resistant layer and T a , 0° for the wear-resistant layer. It goes without saying that you can use whatever materials you have.

Each of these layers is also formed to a desired thickness by a conventional method such as sputtering.

The conductive pattern of the conductor layer made of aluminum or aluminum alloy in the terminal portion is formed when the conductive pattern is formed on the head surface. The plating layer of the base metal for electrolytic adhesion is generally formed by electroless plating of nickel, as shown in FIG. In the case of copper, it can be formed by electroplating. Further, these surface treatments are preferred for obtaining easy solderability when the conductor is made of aluminum or aluminum alloy. Further, the base treatment method can also be performed by vapor deposition.

Connections to flexible printed circuits (FPC), which make electrical connections to external circuits, are made by soldering.
In order to achieve this, the terminal section is characterized in that a metal layer made of an easily solderable metal or an alloy thereof having a higher melting point than the material used for the terminal section of the FPC is formed on the conductor layer. . This metal layer made of easily solderable metals or their alloys is usually soldered at the terminals of the FPC using eutectic solder (melting point 18
3°C), it is most suitable to use tin (melting point: 232°C), which has good compatibility, by electrolytic plating.
Zinc, cadmium, iron, lead, nickel, copper, palladium, silver, gold, or an alloy thereof can be used, and the forming method can be electrolytic plating, electroless plating, vapor deposition, or melt dipping. . In particular, nickel or copper is used as a base metal, and since it is excellent as an easily solderable metal, it is the most economical material that can be used for electrical connection with an external circuit as it is.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. In the figure, the same parts as in FIGS. 7 and 8 shown as conventional examples are given the same reference numerals, and detailed explanations will be omitted.

As shown in FIG. 1, TajcAr and N are deposited on a so-called glazed alumina substrate, in which the surface of an insulating substrate 1 made of alumina or the like is covered with a thin glaze layer 2.

0.05 ~ by gas glue active sputtering method
Heat generating resistor layer 3 made of Tag N with a thickness of 0.2 μm
Then, a conductor layer 4 made of AI with a thickness of about 2 μm is formed.
form. Then, as shown in Figure 3, perform the steps (■ ~ @) in the direction of the arrows in the figure. A. Apply resist coating (step ■) by repeating conventional masking twice using photolithography technology.
), pre-bake (process ■), alignment/exposure (process ■), phenomenon/rinsing (process ■), post-bake (process ■)
), Al etching (process ■), TazN etching (
Process ■), resist stripping (Process ■) and re-coating the resist Process ■), pre-bake (Process [phase]), alignment/exposure (Process ■), phenomenon/rinsing (Process @),
Post-bake (process O), Al etching (process [phase]
) Then, the resist@[I (step@) is performed in order. Therefore, the electrode part and heat generating part pattern are formed in step 15. Next, after covering the terminal part 11 with a metal mask, a SiO film with a thickness of about 2 μm is applied. The head surface 12 is manufactured by forming by sputtering an oxidation-resistant layer 6 made of a film and a wear-resistant layer N7 made of TatOs with a thickness of about 5 μm.

. Next, in the process shown in FIG. 4, electroless plating is selectively applied to the aluminum layer in the area of the terminal portion 11 (see FIGS. 2, 5, and 6), and as shown in FIG. A nickel-phosphorous alloy layer 14 of an easily solderable metal is formed on the surface. Alternatively, as shown in Fig. 6, the entire surface of the terminal is covered with a metal layer serving as a base, and then a tin layer 15 is formed by electrolytic plating to form the terminal portion 11 shown in Figs. 1 and 2, and then the external circuit is formed. (
(not shown).

According to this embodiment, since the terminal portion 11 is plated with nickel or tin, the entire surface can be coated with a uniform layer thickness, and the F
When soldering to a PC terminal (not shown),
Since the solder layer of the terminal uses eutectic solder, the heating temperature is lower than the melting point of nickel or tin during connection, and the eutectic solder 18
By setting the temperature higher than 3°C, only the solder layer made of eutectic solder of the FPC terminal melts and the connection is made, so the occurrence of bridging is extremely reduced, manufacturing management is easy, and the manufacturing yield is significantly high. .

〔Effect of the invention〕

As described above, the thermal head of the present invention includes a case in which a metal layer plated with nickel, copper, or an alloy thereof is formed on a conductor layer made of aluminum or an aluminum alloy in the terminal part, and is used alone; Furthermore, since an easily solderable metal is electrolytically plated on the plated metal layer, when soldering with the FPC terminal, the FP
Only the eutectic solder on the C side melts, and the amount of molten metal that causes bridging is small, making it easy to set FPC pressurization and heating conditions. This has the effect of significantly reducing the occurrence of short-circuit defects.

[Brief explanation of the drawing]

1 to 6 relate to the present invention; FIG. 1 is an enlarged sectional view showing one embodiment of the thermal head of the present invention cut along line c-c' in FIG. 2; 3 is a plan view showing the thermal head of the present invention, FIG. 3 is a process diagram showing a photo process for making a conductive pattern of the thermal head of the present invention, and FIG. 4 is a nickel layer of the thermal head of the present invention.
5 and 6 are cross-sectional views showing the terminal portion of the thermal head of the present invention. FIGS. 7 and 8 are related to a conventional example, and FIGS. 7 is an enlarged sectional view showing a conventional thermal head taken along the line AA' in FIG. 8, and FIG. 8 is a plan view showing the thermal head. 1... Insulating substrate, 2... Glaze layer, 3...
... Heat generating resistor layer, 4... Conductor layer, 6... Oxidation resistant layer, 7... Wear resistant layer, 11... Terminal section, 12
...Head surface, 14...Nickel layer (metal layer)
, 15... tin layer. f'! 1<':,'+ Agent Patent Attorney 2 Kenjibe (Shadow. Ino),・Fig. 1 1I2 Fig. 2 Fig. 3 Fig. 48!1m Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (2)

[Claims] (1) A glaze layer is provided on an insulating substrate, a heating resistance layer is provided on the glaze layer, a conductor layer is further laminated, and the head surface that is pressed against the paper surface for printing is connected to the heating resistance layer and the conductor. A head surface is provided by removing a part of the layer and laminating an oxidation-resistant layer and an abrasion-resistant layer in this order, and a terminal portion connected to the head surface, and a eutectic layer is formed on the conductor layer extending from the head surface. A thermal head comprising a metal layer made of an easily solderable metal or an alloy thereof having a melting point higher than that of solder. (2) The conductor layer of the thermal head is formed by vapor deposition of aluminum or an aluminum alloy, and the terminal portion connected to the head surface is coated with nickel, copper, or an alloy thereof by plating. Form a metal layer of
The thermal head according to claim 1, further comprising electrolytically depositing the easily solderable metal on the underlying metal layer.