JPH0323734Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a driver-mounted thermal head.

[Summary of the idea]

In the mounting structure of a thermal head equipped with a driver IC, an IC with a driver output terminal on one side of the IC and a control signal input terminal on the opposite side is used as the driver IC. It has circuit wiring for energization and control signal input wiring, and has multiple control signal input wiring.
Manufactured by adopting a mounting structure characterized by attaching the resistor board to the IC and connecting it with a bonding wire to a resistor substrate formed by a single layer pattern divided into IC units or divided except for the ground line. This simplifies the manufacturing process by making it easier to discover and correct defects during printing, improves yield, and reduces costs.It also enables improved printing quality, faster printing speeds, and high-density packaging. This is how it was done.

[Conventional technology]

A thermal head equipped with a driver IC is a thermal head in which the output terminal of a driver IC that drives a heat-generating resistor and a heat-generating resistor are connected 1:1 inside the thermal head.
In addition to the driver circuit, it includes a signal conversion circuit that converts multi-bit serial pixel signal input into parallel output, and a control circuit that determines print timing.
It has a control signal input terminal for controlling the operation of these circuits.

The mounting structure of such a thermal head includes wire bonding method, inner lead bonding method using tape carrier, outer lead bonding method, flip chip bonding method, etc. depending on the method of connecting the driver IC and various wiring inside the thermal head. However, examples of the wire bonding method according to the present invention include the following.

Ceramic substrates are mainly used as the substrate for forming the heating resistors of thermal heads because they are advantageous in terms of their heat dissipation characteristics, and the control signal wiring for the driver IC is also connected to the substrate in the direction in which the heating resistors are arranged. After forming a plurality of control signal wirings having terminals and forming an insulating film on areas other than the through-hole portions, one second control signal wiring is formed for each driver IC, and at the same time matrix wiring with bonding pads is formed. I was using it. A thermal head is formed by connecting the output terminal of the driver IC, the control signal input terminal of the driver IC, and the control signal wiring to such a board using bonding wires. (FIG. 4) Furthermore, Japanese Patent Laid-Open Publication No. 78867/1986 discloses a method in which a single layer is used to simplify the control signal wiring as described above, and it is formed on the same substrate as the heating resistor. (Figure 5) [Problems to be solved by the invention] However, the above method had the following problems.

In the first method, it is necessary to form a multilayered and complex pattern on the same substrate at the same time as a pattern that requires a precision pattern of a heating resistor and circuit wiring for energizing it, which leads to a decrease in yield. In addition, in order to form the control signal wiring as mentioned above, three masks are required for wiring formation in the manufacturing process, which results in a time-consuming process and is a factor that increases the price of the thermal head. It was becoming. Furthermore, if there is omission of inspection and correction of defects such as ovens and shots in the first control signal wiring, there is a problem that it becomes impossible to correct them after forming the insulating film.

In the second method, the manufacturing process is simplified in that the control signal wiring is in a single layer, and it is easy to modify. Bonding pads for control signal input are formed from the terminals to each of the many driver ICs to prevent the wiring from crossing over, making them extremely detailed, resulting in lower yields and troublesome inspections during manufacturing. Various problems arose.

Furthermore, in recent years there has been a strong demand for higher printing numbers in thermal heads, and as a means of achieving this, the conventional method of dividing a large number of heating resistor elements into several pieces has been It has been considered to increase the speed by reducing the number of divisions as much as possible, but in this case, the number of heating resistor elements to be driven at once is large, resulting in a flowing current. This means that
It is necessary to increase the current capacity related to the driver circuit in the control signal wiring. However, in the case of the first method, in order to increase the current capacity, it is necessary to make the ceramic substrate larger and the wiring thicker, which poses a problem in terms of board cost, while the second method has the problem of making these wiring thicker. Therefore, problems such as difficulty in pattern design in a single layer are expected.

The present invention was devised to solve the problems of the prior art, and aims to provide a thermal head mounting structure that is lower in cost and can meet modern demands.

[Means for solving problems]

In order to solve the above problems, the present invention provides a signal conversion circuit that converts a multi-bit serial image signal input into a parallel output, a driver IC that includes a multi-bit output timing control circuit, and a driver circuit.
For thermal heads equipped with
As an IC, a driver output terminal is placed on one side of the IC,
The control signal input terminal is placed on the opposite side.
An IC is used, which has a heating resistor, circuit wiring for energizing the heating resistor, and control signal input wiring, and the control signal input wiring is divided into multiple IC units. A mounting structure in which the resistor is mounted on a resistor board formed with a single layer pattern and connected with bonding wires. Only the ground line of the driver circuit during control signal input wiring is common to all ICs, and other wiring is divided into multiple IC units. The mounting structure uses a resistor board with a single layer pattern.

[Effect]

In the mounting structure of the driver-equipped thermal head configured as described above, the control signal input wiring is a single-layer pattern, and the structure is divided into multiple IC units, which eliminates the need for many masks. It can be manufactured through a simple process, inspection is easy, and a low-cost thermal head can be provided.

In addition, by using an IC with a driver output terminal on one side and a control signal input terminal on the opposite side, the ground line of the driver circuit, which requires a large capacitance, can be wired thickly under the IC. In addition, this ground line can be shared by all ICs for heat dispersion, making it possible to provide a thermal head that can meet the demands for higher speeds.

[Example 1] An example of the present invention will be described below based on the drawings.

In FIG. 1, on a resistor substrate 1 made of ceramic, glass, etc., there is a heating resistor 2, a circuit wiring for supplying current to the heating resistor, which corresponds to a common electrode wiring 3 and one heating resistor. A bonding pad 6 is formed for connecting the individual electrode 4 to the output terminal 10 of the driver IC. Furthermore, control signal input wiring 7 is provided on the resistor substrate 1.
is terminal 12 for control signal input and driver
It has an IC control signal input terminal 11 and connects two ICs.
Divide the driver IC 5 into the heating resistor 2.
It is formed through a region that is attached in parallel to the arrangement direction. To explain the above control signal input wiring 7 in detail, the ground line 8 of the driver circuit is closest to the driver IC, and although not shown in the drawing, is formed thickly to include the mounting area of the driver IC, and other lines. The control signal input wirings are formed in a single layer pattern so that they do not intersect with each other in the lower region.

Here, to explain the material, the material for the heating resistor 2 is a ruthenium oxide based resistor in the case of a thick film type thermal head, and a ruthenium oxide based resistor in the case of a thin film type thermal head.
_Ta2N , Ta-Si-O, Ta-Si, etc. are used.
Further, in the above-mentioned various types of wiring, gold paste is mainly used for the thick film type, and Al, Au/Cr, etc. are used for the thin film type.

Further, as a method for forming these wirings, they can be formed in one step by a printing method or a photoetching method.

The resistor substrate 1 thus formed was mounted in the following manner. First, the driver IC 5 is die-bonded to the IC mounting area using a die-bonding agent, and the bonding pad 6 on the individual electrode 4 is connected to the output terminal 10 of the driver IC using a bonding wire 9 made of gold or aluminum. The control signal input terminal 11 of the head was connected to the bonding pad 6 on the control signal input wiring 7, and sealing was performed to protect the driver IC and bonding wire, thereby obtaining a driver IC-mounted thermal head.

Here, the terminal arrangement of the driver IC is such that the output terminals are arranged in a straight line or in a staggered manner on one side, and the control signal input terminals are formed in a straight line or a similar shape on the opposite side. This arrangement is intended to effectively use the area below the driver IC as a wiring contrivance, such as arranging the ground line of the driver circuit.

[Example 2] Next, as another method, a thermal head as shown in FIG. 2 was manufactured.

This is done by making the ground line 8 of the driver circuit during control signal input wiring a common pattern for all ICs, making use of the driver IC mounting area and forming it thickly (not shown in detail in the drawing), so that the input terminals can be taken out from each part. Other than that, the configuration is the same as that in FIG. 1. Implement this in the same way as above,
A driver-equipped thermal head was obtained.

When these thermal heads were evaluated by applying a control signal using methods such as pressure bonding using a flexible board, crimping, or wire soldering, there were no problems with both electrical and mechanical reliability. It was comparable to conventional thermal heads. In addition, in the second thermal head, the ground line of the driver circuit is
Since it is formed using the common IC mounting area, the heat generated by driving the driver IC is dispersed.
The influence of heat on printing could be leveled out, and even printing was possible.

[Effect of idea]

As described above, according to the present invention, the control signal input wiring is made into a single-layer pattern and divided into multiple ICs, making it possible to form a pattern in one process, and also to inspect the pattern after formation. Because it is divided, defects can be easily found, and since it is a single-layer pattern, it is easy to make corrections, which simplifies each process, improves yield, and reduces the cost of the thermal head.

Furthermore, by making the ground line of the driver circuit common to all ICs, it is possible to disperse the heat generated by driving the driver IC, and it is possible to improve printing quality.

Furthermore, by using an IC with an output terminal on one side and a control signal input terminal on the opposite side as a driver IC, the area under the IC can be used for wiring related to the driver circuit (ground line, etc.).
By making the wiring thicker and increasing the current capacity, it is possible to make improvements such as this, and it is also possible to cope with the recent high-speed printing.

In addition, according to the present invention, as shown in FIG. 3, multiple pieces are arranged on the driver IC in a stairway, and the control signal input wiring is formed in a single layer pattern using the area under the IC. In order to prevent the IC and wiring from being shot, it is possible to coat the IC mounting part with an insulating material for mounting, and it can also be applied to high-resolution thermal heads such as 16 dots/mm. High-density packaging is also possible.

The wiring method for control signal input wiring is as follows:
The method is not limited to the method described in this embodiment, and various layouts can be selected as long as a single layer pattern is possible.

[Brief explanation of the drawing]

1 and 2 are plan views showing essential parts of embodiments 1 and 2 of the driver IC-equipped thermal head of the present invention, FIG. 3 is a plan view showing an application example of the present invention, and FIG.
5 are plan views showing patterns of conventional control signal input wiring. 1...Resistor board, 2...Heating resistor, 3...
Common electrode wiring, 4... Individual electrode wiring, 5... Driver IC, 6... Bonding pad, 7... Control signal input wiring, 8... Ground line, 9...
Bonding wire, 10...Output terminal, 11,
12...Control signal input terminal.

Claims (1)

[Claims for Utility Model Registration] (1) A thermal head equipped with a driver IC including a signal conversion circuit that converts a multi-bit serial image signal input into a parallel output, a multi-bit output timing control circuit, and a driver circuit, A resistor board having a heating resistor, circuit wiring for supplying current to the heating resistor, and control signal input wiring divided into multiple IC units and formed in a single layer pattern is provided, and a driver is provided on one side. A driver IC is provided in which an output terminal is arranged and a control signal input terminal is arranged on the other side opposite to this driver output terminal, and the driver
A mounting structure for a driver IC-mounted thermal head, characterized in that an IC is mounted on the resistor substrate and connected to each of the wirings using bonding wires. (2) Only the ground line of the driver circuit
A mounting structure of a thermal head equipped with a driver IC according to claim 1 of the utility model registration claim, characterized in that the IC is common.