JPH0630886B2 - Thermal head - Google Patents

Description

The present invention relates to a thermal head used in a thermal printer or the like.

(b) Conventional Technology A thermal head used in a serial type thermal printer is generally configured so that the head portion can be inserted into and removed from a connector. This is to enable a plurality of types of thermal heads with different points depending on the life of the thermal head to be selectively replaced.

The structure of such a conventional thermal head which can be inserted and removed is shown in FIGS. 3 and 4. In FIG. 3, reference numeral 5 denotes a ceramics board, which is provided on the surface of the ceramics board 5 with respect to a heating portion 6, a common lead 7 for supplying a current to the heating portion 6, a plurality of individual leads 8 and a connector (not shown). Each of the plurality of connection terminals 4 is formed. Further, a drive circuit component ((IC) 9 for driving the heat generating portion 6 is die-bonded between the connection terminal 4 of the ceramics substrate 5 and each lead, and the drive circuit component 9 and the connection terminal 4 are connected.
The drive circuit component 9 and the lead 8 are electrically connected by wire bonding. Also,
By joining the metal plate 10 to the back surface of the ceramic substrate 5, the heat generated from the heat generating portion 6 is radiated. In the thermal head configured as described above, a signal is input from the connection terminal 4 via the connector, and the drive circuit component 9 generates heat by selectively supplying a drive current between the individual lead 8 and the common lead 7. The dots of the part 6 are heated.

The conventional example shown in FIG. 4 is a thermal head of a type in which a flexible board is used for the insertion / removal section, and unlike the case shown in FIG. 3, a plurality of connection terminals 4'are formed at the lower end of the ceramics board 5, The flexible substrate 11 having the connection terminal 4 for the connector formed on the terminal 4'is soldered at the S portion.

(c) Problems to be Solved by the Invention However, such a conventional thermal head has the following problems. That is, in the thermal head of the type shown in FIG. 3, since the connection terminals 4 formed on the ceramics substrate are formed of a thin film such as vacuum deposition or sputtering like the leads 7 and 8, the connection is made. The wear resistance of the terminal 4 is low and the number of times of insertion and removal is small. In the thermal head of the type shown in FIG. 4, since the portion to be inserted into the connector is the flexible substrate, defective press contact is likely to occur, and mechanical strength is low. There is a problem in terms of reliability such as occurrence.

Further, in any of the thermal heads, it is necessary to specially bond a metal plate such as aluminum as a heat dissipation plate to the ceramics substrate, and there is a problem that the number of parts is large.

An object of the present invention is to provide a thermal head that solves the above-mentioned conventional problems and enables cost reduction.

(d) Means for Solving the Problems The thermal head of the present invention is a thermal head having a connection terminal that can be inserted into and removed from a connector, and is connected near the end of a metal plate whose surface is covered with an insulating film. A head chip on which terminals are formed and a heating portion and leads are formed on a substrate, and a driving semiconductor integrated circuit chip for driving the heating portion are mounted on the metal plate, and the driving semiconductor integrated circuit chip and the driving semiconductor integrated circuit chip are attached. It is characterized in that the connection terminal and the drive semiconductor integrated circuit chip and the lead of the head chip are electrically connected by bonding wires.

(e) Action In the thermal head of the present invention, the connection terminal is formed near the end of the metal plate whose surface is covered with the insulating film, and the head chip having the heat generating portion and the lead formed on the substrate is mounted. In addition to the head chip, the connection terminal can be a terminal having a large film thickness, and the wear resistance of that portion can be easily enhanced. Further, a driving semiconductor integrated circuit chip for driving the heat generating portion is mounted on the metal plate, and a space between the driving semiconductor integrated circuit chip and the connection terminal and a space between the driving semiconductor integrated circuit chip and the lead of the head chip are respectively provided. Since it is configured to be electrically connected by the bonding wire, the height of the driving semiconductor integrated circuit chip and the bonding wire can be kept low. Further, the heat generated by the driving semiconductor integrated circuit chip and the heat generated by the head chip are efficiently radiated by the metal plate. Furthermore, the number of parts as a whole is small, and the complicated work involved in the alignment between the parts is also reduced.

(f) Embodiment FIGS. 1A and 1B are a plan view and a side view showing the structure of a thermal head according to an embodiment of the present invention. Also, the second
Figures (A) and (B) show plan views of each component before the thermal head is assembled. Fig. 2 (A) is a component mainly composed of a metal plate, and (B) is a head chip, and the thermal head is composed of these two components and a semiconductor integrated circuit chip for driving a heat generating portion (to be referred to as "driving circuit" hereinafter). parts"
Say. ) And composed.

In FIG. 2 (A), 3 is obtained by spraying ceramic powder such as alumina on a metal plate such as iron, or by applying enamel enamel and baking it.
An insulating film is formed on the surface, and a plurality of connection terminals 4 for the connector are formed on the lower end of the metal plate by printing or baking a conductive paste, or by vacuum evaporation or sputtering. Unlike the pattern of the leads of the head chip, which will be described later, the connection terminal 4 has a relatively thick film thickness and uses a metal material having high wear resistance to enhance reliability of insertion and removal into and from the connector. Since the connection terminals 4 have a coarse terminal pitch, they can be sufficiently formed by screen printing and baking of a conductive paste, and in that case the structural cost can be reduced.

In FIG. 2 (B), 5 is a ceramics substrate such as alumina, on the surface of which a heating portion 6, a common lead 7 for this heating portion 6 and a plurality of individual leads 8 are patterned. Since these leads 7 and 8 have a fine pitch, thin film leads are formed by a photolithography technique, that is, a photoresist process and an etching process.

When the head chip 2 is manufactured by simultaneously patterning a plurality of heat generating portions, common leads and individual leads connected thereto on the surface of the ceramics substrate wafer, and finally dividing into individual head chips, Since the size of one head chip is small, many head chips can be manufactured from one ceramic substrate wafer, and material cost and manufacturing cost can be reduced.

As shown in FIG. 1 (A), the head chip 2 is mounted on the surface of the metal plate 3 on which the connection terminals 4 are formed as described above, and the driving circuit component (IC chip) 9 for driving the heat generating portion 6 is attached. Die-bonding and driving circuit parts 9
Wire bonding is performed between the predetermined pad and the connection terminal 4 by the wire W, and between the predetermined pad of the driving circuit component 9 and the lead 8 of the head chip and between the connection terminal 4 and the common lead 7. Is wire-bonded with the wire W.

In this way, a single thermal head 1 is constructed by combining various components.

(g) Effect of the Invention As described above, according to the present invention, since the connection terminal for the connector can be formed in a separate process from the wiring pattern of the common lead or the individual lead for the heat generating portion, high wear resistance is achieved. The connection terminal can be manufactured by a highly efficient method, and a thermal head having a reliable insertion / removal portion at low cost can be easily obtained. Further, a driving semiconductor integrated circuit chip for driving the heat generating portion is directly mounted on the metal plate, and between the driving semiconductor integrated circuit chip and the connection terminal and between the driving semiconductor integrated circuit chip and the lead of the head chip. Since they are electrically connected by bonding wires, the height of the driving semiconductor integrated circuit chip and the height of the bonding wires can be kept low, and the distance between the mounting part of the driving semiconductor integrated circuit chip and the platen or paper can be reduced. Can be sufficiently separated. Further, the heat dissipation of the driving semiconductor integrated circuit chip is extremely high, and troubles such as malfunction of the driving semiconductor integrated circuit due to the heat generation can be prevented in advance.
Further, since the thermal head is composed of the head chip, the driving semiconductor integrated circuit chip, and the metal plate, the number of parts is small as a whole, and the complicated work involved in the alignment between the parts is reduced, and the manufacturing is facilitated.

[Brief description of drawings]

1 (A) and 1 (B) are a plan view and a side view showing the structure of a thermal head according to an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are components of the thermal head. It is a top view showing a structure. 3 and 4 are views showing the structure of a conventional thermal head, FIG. 3 is a perspective view showing an example thereof, and FIG. 4 is a plan view showing another example. 1 ... Thermal head, 2 ... Head chip, 3 ... Metal plate, 4 ... Connection terminal, 5 ... Ceramic substrate, 6 ... Heating part, 7 ... Common lead, 8 ... Individual lead, 9 ... … Driving circuit components.

Claims (1)

[Claims] 1. A thermal head having a connection terminal that can be inserted into and removed from a connector, wherein a connection terminal is formed near an end of a metal plate whose surface is covered with an insulating film, and a heating portion and leads are provided on a substrate. The formed head chip and the driving semiconductor integrated circuit chip for driving the heat generating portion are mounted on the metal plate, and between the driving semiconductor integrated circuit chip and the connection terminal and the driving semiconductor integrated circuit chip. And a lead of the head chip are electrically connected by bonding wires.