JPH0410954A - Thermal head and manufacturing method therefor - Google Patents

Abstract

PURPOSE:To reduce the number of processes for assembling and to prevent deterioration of flatness caused by fluctuation of the temperature by a method wherein an input wiring and an input member are integrally formed to a heat generating substrate on which a heat generating member is provided, and an integrated circuit of driving semiconductors is installed to the heat generated substrate. CONSTITUTION:An input wiring 20 for a first layer of an input member, an output wiring 14 for an output member, a selecting electrode 14a, and common electrodes 16, 16a are provided over a substrate 2. Then a heat generating body 4, a common electrode 8, and a clothglass 22, an interlayering insulating film, are formed. After this, a conductor 24 for a second layer of the input member, soldering pads 18a, 28 are formed, and an overglass 30, a protection covering, is formed thereon. After bumps are formed by plating a pad 20a for the input wiring 20 and a pad 14b for the output wiring 14 with gold, an IC device 32 is installed and input pins 8 are connected there by soldering.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a thermal head used in printers, facsimiles, etc. and a method for manufacturing the same, and in particular, a driving semiconductor integrated circuit device is mounted on a substrate on which a heat generating part is formed. The present invention relates to a direct drive type thermal head and a manufacturing method thereof.

(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, one heating element is formed on the substrate. , and a wiring board having a connector and input wiring for distributing input signals inputted from the outside to the driving semiconductor integrated circuit device and supplying power are formed as separate boards.

FIG. 7 shows an example, in which a heating element 42 is formed on a ceramic substrate 40, and a driving semiconductor integrated circuit device 44 (sealed with resin) is mounted.
Output wiring connecting the heating element 42 and the integrated circuit device 44 is also formed on the substrate 40. On the other hand, an input wiring board 46 separate from the board 40 is formed of, for example, a flexible printed wiring board, and the input wiring to the integrated circuit device 44 on the board 40 and the wiring of the input wiring board 46 are aligned on the support plate 48. , the press-contact reinforcing plate 5 via the press-contact rubber 50
2, they are connected by being pressure-welded by a pressure-welding screw 54.

FIG. 8 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. is equipped with a driving semiconductor integrated circuit device 64,
The output wiring on the substrate 56 and the integrated circuit device 64 are connected by the wire bonding method, and the input wiring on the input wiring board 60 and the integrated circuit device 64 are also connected by the wire bonding method.

(Problems to be Solved by the Invention) The thermal head shown in FIG. 7 requires a technique for connecting the heat generating board 40 and the input wiring board 46 by pressing them together with high precision, 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. 8, the input wiring board 60 is connected to the wiring of the input wiring board 60 and the integrated circuit device i64.
It is necessary to gold plate the 0 wiring and to miniaturize the through holes of the input wiring board 60 due to higher density, which increases the cost. In addition, when the board 56 and the input wiring board 60 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) According to the present invention, an input section for inputting double power and power from the outside is provided on a substrate on which a heat generating section is formed, and a driving semiconductor integrated circuit device is mounted thereon. Wiring such as input wiring connecting the input section and the driving semiconductor integrated circuit device and output wiring connecting the driving semiconductor integrated circuit device and the heat generating section are further arranged on the substrate.

In order to mount a driving semiconductor integrated circuit device, it is necessary to form bumps on the wiring. When forming bumps by electrolytic plating, one method of the present invention is to form wiring and a heat generating part on a substrate, connect a lead frame to the pad of the wiring that connects the input pin, and form the bump forming area of the wiring. The method includes a plating step in which the exposed substrate is immersed in a plating solution, electricity is applied through the lead frame, and the bump formation area is electrolytically plated to form bumps 1, and after plating, the lead frame is cut at a predetermined position. and use it as an input pin.

(Function) The input wiring and the input part are also integrally formed on the heat generating board on which the heat generating part is formed, and the driving semiconductor integrated circuit device is also mounted on the heat generating board, so the heat generating board is This eliminates the need for assembling the heat-generating board and input wiring board by bonding the input wiring board and the input wiring board onto a support plate, and reduces assembly man-hours and costs. Since it has been
The flatness is not affected by temperature changes and the quality is stable.

(Example) Fig. 1 is an external perspective view of one embodiment, Fig. 2 is a partial plan view showing the heating element and conductor pattern of the same embodiment, and Fig. 3 is a partial plan view of the heating element and conductor pattern of the same embodiment.
4 is a sectional view taken approximately along the line A--A in the figure, and FIG. 4 is a partial plan view showing details of the heating element and input wiring in FIG. 2.

In FIG. 1, a heating element 4 is formed along one end by a thick film method on a ceramic substrate 2 whose surface is covered with a glassy glaze layer, and the other end is connected to the main body of a device such as a printer. The leads of the lead frame are connected by soldering as input bins 8 for receiving input signals and power.

6 indicates an input section including the input bin 8.

Reference numeral 10 denotes a driving section on which a driving semiconductor integrated circuit device is mounted and sealed with resin. Drive unit 10 and heating element 4
The area 13 between is an output section.

Output wiring is formed using a thick film method. 1
8 is a common electrode that supplies driving power to the heating element 4;
It is connected to input bin 8. The common electrode 18 is also formed by the thick film method.

An input wiring section 12 is disposed between the driving section 10 and the input section 6 for distributing the input signal supplied from the input bin 8 to the integrated circuit device of the driving section.
Multilayer wiring is formed using the thick film method.

This will be explained in more detail with reference to FIGS. 2 to 4.

As shown in FIG. 3, the substrate 2 has a structure in which an alumina ceramic substrate 2a is covered with a glassy glaze layer 2b. On the substrate 2, there are input wirings shown by the symbol 2o in FIG. It is made of a thick film of gold resinate (also called metal organic gold). The thickness of the gold resinate is, for example, 0.3 to 1 μm. As shown in FIG. 4, a selection electrode 14a is arranged at the tip of the output wiring 14, and the selection electrode 14a and the common electrode 16a are arranged alternately. 4 is formed by a thick film method. The heating element 4 is made of, for example, ruthenium oxide Ru2O, and its film thickness is, for example, several microns.
m to 10 μm. The common electrode 16a is connected to the wide common electrode 16.

In order to have a two-layer wiring structure in the input section 12, a cross glass 22 is formed as an insulating layer except for the portion where the through hole is formed. On the cross glass 22, a 2M-th horizontal wiring 24.26 (hatched) is formed in the horizontal direction in FIG. 2, and this wiring 24.26 and the common electrode 18 are formed by a thick film method using Ag. The solder pads 18a and 28 to which the input pin 8 is soldered are connected to A.
It is formed by a thick film method using g-Pd. 26 is a ground wiring. The film thickness of these Ag or Ag-Pd is, for example, 10 to 30 μm. Ag-Pt may be used instead of 8g-Pd.

Solder pad portions 18a, 28. A pad portion 36 for connecting elements such as a capacitor or a thermistor, and a driving portion 10 on which a driving semiconductor integrated circuit device is mounted, are covered with a protective film 30.
An overglass is formed as a. The thickness of the cross glass 22 and over glass 30 is, for example, approximately 5 to 10 μm.
It is m.

As shown in FIG. 3, a semiconductor integrated circuit device 32 is mounted in the drive section 10 between the bump 20a of the input wiring 2o and the bump 14b of the output wiring 14 by the flip-chip method. is sealed with resin 38. The integrated circuit device 32 may be connected to the input wiring 2o and the output wiring 14 by the Kaya bonding method.

The input pin 8 is connected to the solder pads 18a and 28 of the input section by solder 34.

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

After printing and firing gold resinate as a first conductor on the substrate 2, patterning is performed by photolithography and etching to form the first layer input wiring 20 of the input section and the output wiring 14 of the output section.
, a selection electrode 14a, and common electrodes 16a, 16 are formed.

Next, the heating element 4 is formed by printing and firing.

The common electrode 18 is formed by a printing method.

A cross glass 22 of an insulating film between the eyebrows is formed.

Thereafter, the second layer conductor 24 of the input section is formed by printing and baking, and the solder pad parts 18a and 28 are formed by printing and baking.

Thereafter, an overglass 3o as a protective film is formed by printing and baking. The pads of the input wiring 2o and the pads of the output wiring 14 are plated with gold to form bumps. After that, the integrated circuit device 32 is mounted and the input pin 8 is connected by soldering.

The input wiring 20 and the output wiring 14 are formed of gold resinate, and when attempting to connect the postal semiconductor integrated circuit device 32 by the flip-chip method as in the embodiment, it is necessary to form bumps on these pads. . The bump can be formed by, for example, gold plating.

Next, a method of forming bumps by gold plating the pads of the input section 1sI20 and the pads of the output wiring 14 will be described.

Since the output wiring 14 is connected to the common electrodes 16 and 18 through the heating element, electrolytic plating can be performed by connecting the common electrode 18 to an electrode of a plating device. However, since the input units Iw120 are independent from each other,
In order to form a bump at the bonding portion of the input wiring 2o, it is necessary to connect the input wiring 20 together to an electrode of a plating device.

FIG. 5 shows one method of applying electrolytic plating.

An electrode 70 for electrolytic plating is formed near the input wiring 20, and each input wiring 20 and the plating electrode 70 are connected with the electrode 72, and the electrode 72 is also connected between the common electrode 18 and the plating electrode 70. The connected substrate 2 needs to be wide enough to form the plating electrode 70.

The plating electrode 70 is connected to each input wiring 2o and the common electrode 18.16 via the electrode 72, and further connected from the common electrode 16 to the output wiring 14 via the heating element 4. Therefore, a resist pattern is formed so as to have openings in the bonding part of the input wiring 20, the bonding part of the output wiring 14, and a part of the plating electrode 70.The resist pattern is immersed in a plating solution for gold plating, and the electrode 70 is connected to the cathode of the plating power source. When plating is applied to the bonding portion of the input wiring 20, a bump 20a is formed on the bonding portion of the input wiring 20, and a bump 1 is formed on the bonding portion of the output wiring 14.
4b are each formed by gold plating. Plating 70a is also formed on the exposed portion of electrode 70. After that, by cutting at the position 74 indicated by the broken line, the input wiring 20 can be made independent from each other, and the input wiring 20 and the common electrode 18 can also be made independent.

FIG. 6 shows another plating method for forming bonding bumps 20a and 14b.

In FIG. 5, a plating electrode 70 is provided.

In FIG. 6, the plating electrode 70 is not provided. Input wiring 20
The solder pad portion 28 of the common electrode 18 and the solder pad portion 18 of the common electrode 18
After forming the lead frame 8, which will become an input via, the lead frame 8, which will become an input via, is connected to the solder pad portions by soldering before plating. The lead frame 8 is connected as one piece, is connected to each input wiring 20, is also connected to the common electrode 18,
Further, the common electrodes 18 and 16 are also connected to the output wiring 14 via the heating element 4. In this state, the lead frame 8 is used as a plating electrode. During plating, a resist pattern is formed so as to have an opening at the bonding portion of the input wiring and the output wiring, the substrate 2 is immersed in a gold plating solution, and the lead frame 8 is connected to the cathode of a power source for plating. As a result, each bonding part has two gold-plated bumps.
0a and 14b are formed. Thereafter, when the lead frame 8 is cut at the position indicated by the broken line 76, a state is completed in which the input pin 8 is connected to the solder pad lip 28 of the input wiring and the solder pad portion 18a of the common electrode 18.

Thereafter, a driving semiconductor integrated circuit device is connected between the bumps 20a and 14b by the flip-chip method.

In this embodiment, since a ceramic substrate whose surface is covered with a glaze layer is used as the substrate, the yield of wiring patterning is improved.

Also, all the wiring is made of thick film material.

It is possible to ensure current capacity and at the same time to produce at low cost and in large quantities. Compared to the WI peritoneal method, it can respond more quickly to changes in patterns.

In the multilayer wiring part, 17! Eyes are Au, second layer is A
Since it is made of Ag or Ag-Pd, the cost can be reduced by 2.

(Effects of the Invention) In the present invention, since the input wiring and the input section are integrally formed on the heat generating board on which the heat generating section is formed, the flatness is not impaired even by temperature changes, improving the quality and making it easier to assemble. Fewer man-hours and lower costs.

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

When forming bumps on which an inductive semiconductor integrated circuit device is mounted by electrolytic plating, the lead frame connected to the pad of the wiring that connects the input pin can also be used as the plating electrode, making it possible to separate the plating electrode on the board. Compared to the case where the substrate is provided and then cut after plating, the substrate can be reduced in size, the number of manufacturing steps can be shortened, and the number of manufacturing steps can be reduced. Thereby, the cost of the integrated thermal head can be reduced.

The lead frame has a lower resistance than the plating electrodes provided on the substrate, so it can uniformly conduct electricity to a large number of bumps arranged, making the plating thickness of the bumps uniform and improving yield. .

[Brief explanation of drawings]

Fig. 1 is an external perspective view of one embodiment, Fig. 2 is a partial plan view showing the heating element and conductor pattern of the same embodiment, and Fig. 3 is a second embodiment.
4 is a partial plan view showing details of the heating element and input wiring in Figure 2, and Figures 5 and 6 are plating on the bonding pads of the wiring, respectively. FIG. 3 is a schematic plan view showing the method. Figures 7 and 8
The figure is a sectional view showing a conventional thermal head. 2...Substrate, 2a...Ceramic substrate, 2b...Glaze layer, 4...Heating element, 8...Input pin, 14 ...Output wiring, 14a...Selection electrode, 16°16a, 18.
...Common electrode, 18a, 28...Solder pad, 20...IM input wiring, 22...
...Interlayer insulating film, 24...2nd layer input wiring, 26...Ground wiring, 32...
Integrated circuit device, 34...Solder.

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. The thermal head is provided with wiring such as input wiring for connecting the semiconductor integrated circuit device for driving and output wiring for connecting the semiconductor integrated circuit device for driving and the heat generating section. (2) Form wiring and a heat generating part on the board, connect a lead frame to the pad of the wiring that connects the input pin, immerse the board in a plating solution with the bump forming area of the wiring exposed, and then The method for manufacturing a thermal head includes a plating step of applying electricity through the lead frame and electrolytically plating a bump forming area to form a bump, and after plating, the lead frame is cut at a predetermined position to form an input pin.