JPH0386560A - Thermal head and production thereof - Google Patents

Abstract

PURPOSE:To obtain a thermal head having a good adhesion between a common circuit conductor and a primary coat and a superior mass-productivity by a method wherein an aluminum-plated film plated under an inert gas atmosphere using a nonaqueous plating liquid is used as the common circuit conductor. CONSTITUTION:On an insulating substrate 11 provided with a glaze layer 14, a plurality of heating resistor films 15 and a plurality of lead films 16 for forming respective heating dot parts 17 are formed by a dry film-forming method. On the resistor films 15 and the lead films 16 where the glaze layer 14 is not formed, a common circuit conductor 13 is disposed, which is an aluminum-plated film electrically plated under an inert gas atmosphere using a nonaqueous plating liquid. On the surface of these films, a protective layer 18 is provided. Furthermore, a solder resist film 22 is provided on a part corresponding to the common circuit conductor 13 to improve resistance to wear and resistance to environment. Printing paper 20 is abutted on the heating dot parts 17 by a platen roller 19 while being fed, whereby a predetermined printing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thermal head in which a common circuit conductor is formed by plating, and a method for manufacturing the same.

(Prior Art) A thermal head for a printer usually has a circuit made of aluminum or the like as a conductor formed on one side of a flat insulating substrate with a thickness of about 1 m.

Conventionally, dry methods such as vapor deposition have been used to form a common circuit using conductors such as aluminum on an insulating substrate, but recently, the feasibility of using electroplating has been studied. It has become so. That is, the advantage of electroplating is that it takes a long time to obtain an aluminum film with a thickness of several micrometers or more, whereas vapor deposition and the like require a short time.

As is well known, in order to carry out electrolytic aluminum plating,
Since it is difficult to precipitate aluminum from an aqueous plating solution, it is common to use a plating solution made of a non-aqueous organic electrolyte. The plating liquid is disclosed in the publication.

By the way, as mentioned above, the common circuit conductor of the thermal head is an issue to which such a plating method is applied.

FIG. 3 shows the overall structure of the thermal head, which includes individual heating circuit groups 12 for forming heating dot groups for printing and a common circuit for these on an insulating substrate 11 with a thickness of approximately 0.8H. A conductor 13 is formed.

FIG. 4 shows the structure of a conventional example of this thermal head. In the figure, an alumina substrate is used as the insulating substrate 11, and on the glaze layer 14 on the surface of the alumina substrate, tantalum or silicic acid (8
102) etc. are formed by sputtering etc., and a plurality of lead films 1 are formed on the upper surface thereof.
6 is formed, and a common circuit conductor 13 is further formed. As the lead film 16 and the common circuit conductor 13, aluminum obtained by a dry film forming method such as sputtering or vapor deposition is used. In addition, each lead film 1 mentioned above
Reference numeral 6 forms a heating dot portion 17 with the resistive film 15 exposed to constitute the heating dot group. Further, a protective film 18 is formed on the surfaces of the lead film 16 and the common circuit conductor 13.

Reference numeral 19 denotes a platen roller that applies the printing paper 20 to the heating dots [17] and prints while feeding the printing paper 20.

Here, the common circuit conductor 13 is connected to all the heating dot parts 1.
Since the lead film 16 is connected to the lead film 16, a high capacitance is required, and a thickness several times or more of the thickness of the individual lead film 16 is desired. Aluminum has good adhesion to the protective film 18 of the heating dot group, and is often used as the common circuit conductor 13 of thermal heads, but dry film formation methods such as vapor deposition have problems in expanding industrial production. In other words, a large amount of capital investment is required, and there is a limit to economical production.

In addition, as shown in Japanese Unexamined Patent Publication No. 63-262253, a glaze layer is partially formed on an insulating substrate, and a common circuit conductor is formed by plating on the part where the glaze layer is not formed. There is also.

However, the common circuit conductor in this example is plated with water-soluble copper, which does not have sufficient adhesion to the underlying layer and requires a long plating time.

(Problems to be Solved by the Invention) As described above, when forming the common circuit conductor of the thermal head, it is difficult to form a thick conductor with large capacitance, and it takes a long time to form. There are problems such as insufficient adhesion with the base layer.

An object of the present invention is to use an aluminum plating film plated in an inert gas atmosphere using a non-aqueous plating solution as a common circuit conductor, thereby achieving good adhesion between the common circuit conductor and the underlying layer and facilitating mass production. It is an object of the present invention to provide an excellent thermal head and a method for manufacturing the same.

[Structure of the invention]

(Means for Solving the Problems) Claim 1 of the present invention relates to a thermal head in which a plurality of resistive films and lead films for forming a group of heating dots and a common circuit conductor therefor are formed on an insulating substrate. The common circuit conductor is made of an aluminum plating film plated using a non-aqueous plating solution in an inert gas atmosphere using a metal thin film deposited on the insulating substrate as a base layer. be.

Claim 2 of the present invention relates to a method for manufacturing a thermal head, in which a resistive film and one or more metals such as aluminum, chromium, titanium, copper, nickel, etc. are formed as a lead film on an insulating substrate. A dry film forming process in which a thin film is deposited by sputtering or vapor deposition, a process in which the deposited metal thin film is masked with a corrosion resistant material except for the portion corresponding to the common circuit conductor, and after this masking, the metal thin film is lowered. It is equipped with a wet film forming process to form an aluminum plating film as a common circuit conductor using a non-aqueous plating solution in an inert gas atmosphere as an electric bridge in a geological formation.

(Function) The thermal head according to claim 1 of the present invention is capable of forming a common circuit conductor for a group of heat-generating dots by electrolytic aluminum plating using a non-aqueous plating solution in an inert gas atmosphere. Compared to the case where a common circuit conductor is formed by a method, a common circuit conductor having a large thickness, that is, a large capacity can be formed in a short time, and the structure is optimal for a thermal head having a group of heat generating dots with low resistance. Further, since these can be directly plated as a base layer on a resistive film, a lead film, etc. formed on an insulating substrate, the adhesion with the base layer is improved and the plating time is shortened. The adhesion achieved by this direct plating can be maintained and sufficiently guaranteed, especially since the surface to be plated can be easily activated in an inert gas.

The method for manufacturing a thermal head according to claim 2 of the present invention is to form a resistive film and a lead film on an insulating substrate by a dry film forming method, then mask the parts other than those that will become common circuit conductors, and then apply an inert gas atmosphere. Below, electrolytic aluminum plating is performed using a non-aqueous plating solution to form a mini-RAM plating film on the common circuit conductor.

(Example) Hereinafter, an example of a thermal head and a method for manufacturing the same according to the present invention will be described with reference to the drawings.

The thermal head shown in FIG. 1 includes a plurality of heating circuit groups 12 for forming heating dot groups on an insulating substrate 11, and a common circuit conductor for these circuits, similar to those shown in FIGS. 3 and 4. 13.

An alumina substrate is used as the insulating substrate 11, and a glaze layer 14 is integrally formed on the surface thereof. This glaze layer 14 is formed not on the entire surface of the insulating substrate 11, but on the negative side edge.

On the insulating substrate 11 having the glaze layer 14, a plurality of heat generating resistive films 15 and a plurality of lead films 16 for forming each heat generating dot portion 17 are formed by a dry film forming method. Further, on the resistive film 15 and the lead film 16 in the portion where the glaze layer 14 is not formed, a common circuit conductor is formed by an aluminum plating film electroplated using a non-aqueous plating solution in an inert gas atmosphere. 13 is located. A protective film 18 is formed on these surfaces, and a solder resist film 22 is further provided on a portion corresponding to the common circuit conductor 13 to improve wear resistance and environmental resistance.

The thermal head configured in this manner performs predetermined printing by applying the printing paper 20 to the heating dot portion 17 by the platen roller I9 and feeding the printing paper 20.

Here, a common circuit conductor 1 is formed by electrolytic aluminum plating.
3, a protrusion 131 as shown is generated,
When printing is performed as a thermal head, it may come into contact with the printing paper 20, resulting in printing with black streaks or paper scum adhering to the surface of the thermal head. Since it is formed in a portion where the layer I4 is not present, the printing paper 20 will not come into contact with the protrusions 13s of the common circuit conductor 13 even if the thickness is made sufficiently large to obtain a large current carrying capacity. Therefore, there is no occurrence of black streak printing or accumulation of paper waste.

For example, if the height of the glaze layer 14 is 60μ, if the part without the glaze layer 14 (the part where the common circuit conductor 13 is formed) is separated from the heating dot part 17 by 1111 or more, the printing paper 2G Conductor 13 (thickness 15II
Projection 131 (with a thickness of 5 μm) on
Printing can be performed without touching the surface. Therefore, the above-mentioned black streaks and paper scum do not occur. In addition, when increasing the plating thickness of the common circuit conductor 13,
The position may be set further away from the heating dot portion 17.

Next, a method of manufacturing the thermal head as described above will be explained with reference to FIG.

First, an insulating substrate 1 made of alumina or the like having a glaze layer 14
For (2), a resistive material such as tantalum or silicate (CS, O, Preferably aluminum (^1).

A thin film (thickness: 1 μm) of one or more materials such as chromium (C), titanium (Ti), copper (Cu), nickel (Ni), etc. is formed by sputtering. 16, a part of the resistive film 15 is exposed in order to form a heating dot part 17. After that, an etching process using a photoresist and a photomask is performed, and a photoresist or Teflon or the like is etched.
As shown in FIG. 2, only the portion where the common circuit conductor 13 is plated is exposed, and the rest is insulated (masked).

In FIG. 2, 23 is a photoresist film (thickness of about 2O
n), as mentioned above, after processing such as exposure and development,
The non-plating area is masked.

24 is a lead electrode for plating, and a resistive film 1 made of tantalum, S, O2, etc. is sputtered on the insulating substrate 11.
5 and a lead film 16 made of aluminum or the like.

That is, the resistive film 15 and the lead film 16 serve as a base layer for plating, and the base layer is directly plated. As the lead film 16, in addition to the above-mentioned aluminum, a multilayer thin film of one of chromium, titanium, copper, nickel, etc. can also be used.

Reference numeral 25 denotes a Teflon jig, which is attached to cover the lead electrode 24 and the non-plated portion of the insulating substrate 11.

The lead electrode 2 for plating is masked as described above.
Electrolytic aluminum plating is applied to the insulating substrate 11 to which 4 is attached to form a common circuit conductor 13. This plating is carried out in a molten salt bath (nonaqueous type) in an inert gas (for example, nitrogen) atmosphere.

That is, for example, although not shown, the masked insulating substrate 11 as shown in FIG. It is inserted through a slit-shaped opening.

Then, while immersed in a non-aqueous plating solution containing 1 mole each of aluminum chloride and butylpyridium chloride, the vertical plating surface is opposed in parallel to a plate-shaped aluminum anode.

Then, nitrogen gas from which moisture has been removed is supplied as an inert gas from an aeration tube disposed at the bottom of the plating tank between the insulating substrate 11 placed in the plating tank and the anode.

When performing plating, a predetermined power is supplied to the insulating substrate 11 and the anode. Here, a resistive film 15 and a lead film 16, which will serve as a base layer for plating, are connected to the insulating substrate 11 from the current-carrying support member through lead electrodes 24 for plating.
is supplied to

Further, nitrogen gas is supplied to the diffuser tube, and the nitrogen gas is diffused into the plating solution through a large number of small holes formed in the diffuser tube. The nitrogen gas forms a large number of bubbles and rises over the surfaces of the insulating substrate 11 and the anode in the plating solution, stirring the plating solution while causing an upward flow in the plating solution near these.

Therefore, by controlling the amount of nitrogen gas supplied, it is possible to obtain a strong stirring effect even on a highly viscous non-aqueous plating solution. This stirring is performed by a large number of bubbles, but the individual bubbles do not simply float vertically, but move horizontally while changing their shape, making the stirring uniform and reliable. An aluminum plating film having a uniform thickness can be formed on the surface of the insulating substrate 11 to be plated, and the appearance of the plating film is also improved. Then, the anode becomes easier to dissolve, the increase in electrical resistance due to oxidation of the anode surface is reduced, and a plating film can be efficiently formed.

In this way, the nitrogen gas bubbles that stirred the plating solution rise above the plating solution, and the inside of the plating hinoki, which is in a semi-sealed state with only a small slit-shaped opening, is opened.
Fills the space above the plating solution.

Therefore, the space inside the plating tank is filled with nitrogen gas.
The pressure will be higher than that outside. This state is maintained by continuing to supply nitrogen gas, which prevents air from entering the plating tank from the outside, protects the plating solution from moisture and oxygen in the air, and prevents deterioration of plating performance. can be kept to a minimum.

In addition, at a bath temperature of about 25°C and a current density of about 1 A/d rd,
The time required to form a 5 μm aluminum plating film is about 25 minutes.

In addition, prior to aluminum plating, the aluminum vapor-deposited film on the surface to be plated may be cleaned by immersing it in an organic solvent such as dehydrated toluene, or a part of this aluminum vapor-deposited film may be electrolyzed by anodic electrolysis in a plating solution. Etching improves the adhesion of the plating film to the vapor deposited film.

The above-mentioned plating is directly plated on the surface of the base layer, and the adhesion caused by this direct plating is guaranteed to last because the surface to be plated can be easily activated in an inert gas such as nitrogen. . The above activation is achieved by removing the oxide film on the surface simply by immersion in a molten salt plating bath, which is a non-aqueous plating solution, or by performing anodic electrolysis for a few seconds. This helps in starting an average precipitation.

When the common circuit conductor 13 reaches a predetermined thickness (approximately 15 am) by the above plating, as shown in FIG. Use it to separate under pressure. In this way, a conductor having a uniform thickness can be formed without leaving any traces of the plating lead electrode 24.

Thereafter, the masking material is removed to complete the formation of the common circuit conductor 13. Then, as described above, the protective film 18 and the solder resist film 22 are provided.

Note that the electrolytic aluminum plating film formed as the common circuit conductor 13 may be subjected to surface treatment such as electrode oxidation treatment or chromate treatment. This is because not only does this provide excellent corrosion resistance, but also the adhesion to the thin film of oxides such as S and O2, which serves as a protective film, can be improved.

Further, as a masking method, a method of masking by pressing a corrosion-resistant material such as a Teflon plate against the non-plated surface may be adopted.

By forming the common circuit conductor 13 in this manner, it becomes possible to form a thick conductor in a short time (at least 10 times the deposition rate of the vapor deposition method), which has been difficult in the past.

Therefore, it is suitable for industrial production and has an optimal configuration as a thermal head having a group of low-resistance heat-generating dots.

Further, there are no restrictions on the design of the common circuit conductor 13. That is, since resist masking is used, the common circuit conductor 13 can be wired in any shape. In other words, conventionally, metal mask evaporation was used,
The circuit shape on both ends of the substrate was a factor that affected the yield, but resist masking is not subject to such restrictions.

〔Effect of the invention〕

As described above, according to the present invention, a thick film can be easily formed by performing electrolytic aluminum plating in an inert gas atmosphere using a non-aqueous plating solution to form a common circuit conductor. , good printing characteristics can be obtained due to sufficient capacitance due to this thick film thickness. Moreover, the plated portion is in a good state with excellent adhesion to the underlying layer.

Furthermore, the manufacturing method is suitable for industrial production, such as shortening the plating time and not being subject to restrictions on common conductor design.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a thermal head according to the present invention, FIG. 2 is a sectional view showing a plating state in the method of manufacturing the thermal head shown in FIG. 1, and FIG. 3 is a perspective view of the thermal head. , FIG. 4 is a sectional view showing a conventional thermal head. 11...Insulating substrate, 13...Common circuit conductor, 15...Resistive film, 16...Lead film, 17...Heating dot part. 4 Riri”

Claims (2)

[Claims] (1) In a thermal head in which a plurality of resistive films and lead films for forming heat-generating dot groups and a common circuit conductor for these are formed on an insulating substrate, the common circuit conductor is adhered to the insulating substrate. 1. A thermal head comprising an aluminum plating film plated using a non-aqueous plating solution in an inert gas atmosphere using a metal thin film as a base layer. (2) a dry film forming step of depositing a resistive film and a metal thin film as a lead film of one or more types of aluminum, chromium, titanium, copper, nickel, etc. on the insulating substrate by sputtering or vapor deposition; The deposited metal thin film is masked with a corrosion-resistant material except for the portion corresponding to the common circuit conductor, and after this masking, a non-aqueous plating solution is applied in an inert gas atmosphere using the metal thin film as an electrode of the base layer. 1. A method of manufacturing a thermal head, comprising: a wet film forming step of forming an aluminum plating film as a common circuit conductor using the aluminum plating film.