JPS63268663A - Thermal head substrate and manufacture thereof - Google Patents

Abstract

PURPOSE:To lower the resistance of a conductor, improve the ununiformity of printed density, reduce etching time and obtain a high pattern accuracy, by composing an electrode conductor layer of an undercoat metallic layer provided on a heat generating resistor layer for Cu plating and a plated Cu layer provided on the undercoat metallic layer. CONSTITUTION:A common electrode body, a ground terminal and an external connection terminal part are provided by sequentially providing a plate Cu layer 41, a plated Cu layer 42 and a plated Ni layer 5 on an insulating thin film layer (Ta2O5 layer) 2 and a heat generating resistor layer 3 which are provided on a glazed alumina ceramic substrate 1. A heat generating resistor layer 6 is protected by an abrasion-resistant layer 7, and the parts exclusive of a bonding part for mounting a driving IC and an external connection terminal are protected by an insulating resin. The plated Cu layer 42 has a thickness of about 20mum, so that a difference in voltage drop based on a difference in circuit resistance is small even when a large current is passed at the time of operating a thermal head, and a uniform printed density can be ensured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a thermal head substrate in which a heating resistor and a wiring pattern connected to the heating resistor are formed on an insulating substrate by film technology, and a method for manufacturing the same. In particular, the present invention describes a thermal head substrate having an Is conductor pattern and a method for manufacturing the IyJ.

[Conventional technology]

Conventionally, when printing with this type of thermal head substrate, for example, B-4 size, dot density of 8 dots/lead,
When using the 1-line 4-division printing method, maximum 2O is applied to the common electrode body.
It is necessary to supply a current around A, and voltage drop due to conductor resistance becomes a problem.

In other words, the farther the printing position of the thermal head is from the current supply point, the lower the voltage applied to the heating resistor and the lower the amount of heat generated, resulting in a thinner printing density. In order to improve such print density unevenness, conventional paper head substrates have a common electrode body, a driving IC ground terminal,
And thick films such as gold and silver are used for external connection terminals,
It has thickened body layers.

FIG. 7 is a partial plan view showing the conductor arrangement of the former example, and FIG. 8 is a cross-sectional view taken along the line AA in FIG. 7.

As shown in FIG. 7, there is a common electrode body 2o1 on one side of the heating resistor 21, and an individual electrode body 202 on the other side, and power for printing is supplied to the heating resistor 21. Common electrode body 2
In o1, glazed alumina ceramic substrate 1
A thick layer of gold, silver, etc. is formed on top of the insulating layer 2 and the heating resistor shown in FIG. Two conductor layers 9 are formed to conduct current between the thick film 8 and the M conductor wiring layer 8.

In the external connection terminal 22, the thick gold film S is used as it is as a crimp connection terminal. A drive 1c is mounted on the ground terminal 23.

(Problems to be Solved by the Invention) In the conventional thermal head substrates described above, the former uses a thick film of gold, silver, etc., so the initial cost of the substrate itself is high; In addition, since an insulating layer is formed to protect the thick film during etching of the culm after covering the thick film, the common electrode body and driving IC ground terminal cannot be directly connected between the thick film and the wiring conductor layer. Electrical continuity cannot be obtained, it is necessary to connect the thick film and the wiring conductor layer by a separate means, and furthermore, the thick film oxidizes over time, resulting in low reliability.

In addition, the latter method of increasing the thickness of the conductor layer is uneconomical in terms of the equipment capacity of the film forming equipment, and if a high dot density is required, the conductor layer must be etched to a large thickness during pattern formation. Therefore, side etching is severe and the desired pattern cannot be etched.

[Means for solving problems]

In the thermal head substrate of the present invention, the electrode conductor layer is
The base metal 1iAW1 for Cu plating formed on the heating resistor diagram, and the base metal 1! ! C formed on the layer
It is composed of a U-metal layer.

Further, among the manufacturing methods, the method described in claim 2 includes the steps of: forming a Cu-plated base metal R layer on the bond on which the heat generating resistor diagram is formed by sputtering method; After forming a wiring pattern on the heating resistor diagram and the base metal layer for Cu plating, mask the part of the pattern that will become the heating resistor with photoresist or the like, and mask the part that will become the common electrode body. The method includes a step of plating Cu to a predetermined thickness on a base metal layer for Cu plating by using an electrolytic Cu plating method using as a current supply source.

Further, among the manufacturing methods, the method according to claim 3 includes the steps of forming the heating resistor diagram and then forming a Cu-plated base metal a layer on the upper surface thereof by sputtering method; After forming a wiring pattern on the heating resistor diagram and the Cu-plated base metal IK layer, Cu is applied to the entire surface of the board.
Plating is applied, and further, a mask is applied to the parts other than the part to become the common electrode body, and Cu plating is applied to the part to be the common electrode body. Next, after removing the mask, the entire surface of the substrate is The process includes a step of applying Ni plating, and then a step of completely removing the Ni plating layer and CLI plating layer in the portion that will become the heating resistor by etching.

[Effect]

In this way, by forming the entire electrode body with a Cu plating layer and setting the thickness of each portion to a thickness that corresponds to a predetermined Ti flow density, unevenness in printed portion 1 can be improved.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an embodiment of the thermal head substrate of the present invention, and FIGS. 2 to 5 are an embodiment of the method of manufacturing the thermal head substrate of FIG. 1 according to claim 2. FIG. 1) is a cross-sectional view of a substrate for explaining the step-by-step process.

Next, the manufacturing process will be explained in the order of steps with reference to FIGS. 2 to 5.

(1) Base treatment, heating resistor diagram, and lower conductor layer film formation process (Figure 2) An insulating i11 layer (T
a205 li! ) 2 was formed into a film with a thickness of about 3,000 layers by sputtering, and after forming the heating resistor shown in FIG. Use as a conductor layer.

(2) Conductor wiring pattern forming step A (Fig. 3) Next, C
The u-conductor B41 is etched using an iodine/potassium iodide etchant using a known photoresist processing technique, and then the heating resistor shown in FIG. Then etching is performed to form a wiring pattern.

Generally, when etching a Cu conductor layer, side etching is severe and pattern accuracy is poor, but in this example,
The thickness of the Cu conductor layer is about several 100 to 1000 layers,
Since the etching time is short, the amount of side etching is small and good pattern accuracy can be obtained.

(3) Conductor wiring pattern forming work Pi! B (FIG. 4) Next, the Cu39 layer 41 in the heating resistor portion is etched using the same photoresist processing technique to form the heating resistor 6.

(4) Electrode body forming step (Fig. 5) Next, the heating resistor 6 is masked with photoresist or the like,
cu, the common electrode body of the single body layer 41 as a current supply source,
Cu is deposited on the Cu conductor layer 41 by a known electrolytic Cu plating method.
A plating layer 42 is applied to the common electrode body in an amount of about 20*)1. In this case, since there is a heating resistor between the individual electrode body part of the Cu conductor layer 41 and the common electrode body part, the thickness of the Cu abutment layer 42 ranges from several thousand layers to several thousand. Furthermore, an upper conductor layer is formed by applying a Ni plating layer 5 (approximately 1000 to 2000 layers) for the purpose of preventing oxidation of Cu.

(5) Finishing process (Figure 1) Next, if the connection between the IC and the individual electrode body is a solder bump connection, and the terminal connection method of the external connection terminal section is soldering, the above process will meet the purpose. However,
If the IC and the individual electrode body are connected by wire bonding or the external terminal is connected by crimp, Au plating is applied on the blocking plate M5 of the corresponding part. After that, the heating resistor 6 is covered with a wear-resistant material 117, and the parts other than the bonding part for mounting the IC and the external connection terminals are coated with an insulating resin (not shown) to form the desired thermal head as shown in Fig. 1. The board is completed. Note that in this embodiment, the lower conductor layer does not need to be made of Cu (it may be any metal that is easily plated with Cu).

FIG. 6 is a diagram showing an embodiment of claim 3 of the method for manufacturing a thermal head substrate of the present invention.

Next to step (2) (FIG. 3) of the above-mentioned embodiment, a Cu plating layer 42 is applied in one to three layers over the entire surface of the substrate, and the parts other than the common electrode body are masked, and the common electrode body is coated with a Cu plating layer 42. C
Form about 20 U marks (Figure 6). Next, the masking is removed, limited plating is applied to the metal portion of the substrate, and furthermore, the limited layer and Cu 13 in the portion of the heating resistor 6 are etched and removed, resulting in the structure shown in FIG.

In the previous embodiment, the common electrode body is used as the current supply source, and the individual electrode bodies are plated with Cu via the heat generating resistor 6. However, depending on the resistance value of the heat generating resistor 6, of Cu
The thickness of the plating 11542 varies, and if the resistance is high, the individual electrode body may not be plated at all. However, in this embodiment, since Cu plating is performed before forming the heating resistor 6, there is an advantage that the Cu plating thickness on the individual electrode bodies can be freely adjusted in iqm.

Next, an embodiment of the thermal head substrate of the present invention manufactured by either of the above two embodiments will be described with reference to FIG.

As is clear from the manufacturing method described above, in this embodiment, the common electrode body, the ground terminal, and the external connection terminal portion are connected to an insulating film II (TazOs layer) 2 formed on a glazed alumina ceramic substrate 1, and a heat generating layer. On top of the resistor shown in Figure 3, there is a Cu patch layer 41 and Cu plating! 42 and N
These are formed by sequentially plating the i-plated layers 5. The heating resistor 6 is made of wear-resistant M7, and the parts other than the bonding part for mounting the driving IC and the external connection terminals are protected by insulating resin. The Cu plating layer 42 thus formed has a thickness of about 20
Because it has the same thickness, even if a large current flows during the operation of the thermal head, the difference in voltage drop is small based on the difference in circuit resistance, and printing *r* unevenness can be prevented.

〔Effect of the invention〕

As explained above, in the present invention, in order to make the electrode conductor layer have a two-layer structure, first a base metal layer that is easily plated with Cu is laminated on the heating resistor diagram, and then electric field Cu plating is applied thereon. A Cu plating layer is formed on the upper part, and the conductor resistance is lowered by applying thick Cu plating to areas such as the common conductor where a relatively large current flows and voltage drop due to conductor resistance is a problem. It is possible to improve the unevenness of the garden temperature,
Furthermore, since the etching 0III is short, there is an effect that a high pattern of 11 degrees can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the thermal head substrate of the present invention, and FIGS. 2 to 5 are an embodiment of the method of manufacturing the thermal head substrate of FIG. 1 in claim (2). Similarly, FIG. 6 is a cross-sectional view of the in-process board for explaining an embodiment of claim (3), and FIG. 7 is a cross-sectional view of the in-process board for explaining the process order. A partial plan view showing the conductor arrangement of the conventional example, FIG. 8 is A of FIG.
-A cross-sectional view taken along arrows. 1... Glazed alumina ceramic substrate, 2...
Insulating thin film layer, 3... Heat generating resistor diagram, 41... Cu conductor layer. 42...Cu plating layer, 5...Ni plating corner, 6...heating resistor, 7...wear resistant layer. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7

Claims (1)

[Scope of Claims] 1. A thermal head substrate in which a wiring pattern is formed on a heating resistor layer and an electrode conductor layer laminated on an insulating substrate, wherein the electrode conductor layer is formed on the heating resistor layer. 1. A thermal head substrate comprising: a base metal layer for Cu plating formed on the base metal layer; and a Cu plating layer formed on the base metal layer. 2. A wiring pattern is formed on a heating resistor diagram and an electrode conductor layer laminated on an insulating substrate, and the electrode conductor layer is a base for Cu plating formed on the heating resistor layer. In a method for manufacturing a thermal head substrate comprising a metal layer and a Cu plating layer formed on the base metal layer, after forming the heating resistor layer, a base metal layer for Cu plating is formed on the upper surface by sputtering. Next, after forming a wiring pattern on the heat generating resistor layer and the base metal layer for Cu plating, the part of the pattern that should become the heat generating resistor is masked with photoresist or the like, and a common electrode body is formed. 1. A method for manufacturing a thermal head substrate, comprising the step of plating Cu to a predetermined thickness on a base metal layer for Cu plating by electrolytic Cu plating using the desired portion as a current supply source. 3. A wiring pattern is formed on the heating resistor layer and the electrode conductor layer laminated on the insulating substrate, and the electrode conductor layer is a base for Cu plating formed on the heating resistor layer. In a method for manufacturing a thermal head substrate comprising a metal layer and a Cu plating layer formed on the base metal layer, after forming the heating resistor layer, a base metal layer for Cu plating is formed on the upper surface by sputtering. Next, after forming a wiring pattern on the heating resistor layer and the base metal layer for Cu plating, Cu plating is applied to the entire surface of the substrate, and further, a mask is applied to the parts other than the part to become the common electrode body. Then, after removing the mask, applying Ni plating to the entire surface of the substrate, and then applying Cu plating to the part to become the heating resistor. Ni plating layer and Cu
A method for manufacturing a thermal head substrate, comprising the step of completely removing a plating layer by an etching method.