JPS59215875A - Thermal printing head - Google Patents

Abstract

PURPOSE:To perfectly connect a wiring circuit and conductors to each other and enable to enhance reliability of a head, by a method wherein opening parts are provided in an insulator layer made on wiring circuits, and conductors for electrically connecting the wiring circuits through the opening parts are provided. CONSTITUTION:Heating resistors 112 are provided in a row on an insulated substrate 110 provided with a glaze layer 111, then the first and second common electrode groups 114, 115 constituting the wiring circuits are connected thereto, and the first and second IC groups 116a ..., 117a ... are connected thereto. A common lead 11401 for the common electrode 114 is connected to a conductor wire 126 by an ultrasonic bonder through the opening part 113a provided in the insulator layer, while a common lead 11501 for the common electrode 115 is connected to a conductor wire 126 by an ultrasonic bonder through the opening part 113b. Accordingly, bond between the wiring circuits and the conductors is prevented from being broken by forces generated due to differences in therman expansion between the insulated substrate and the conductors or external forces, and reliability is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal print head for a thermal recording device.

[Technical background of the invention and its problems]

Thermal print heads for thermal recording devices are broadly classified into thin film type, thick film type, and semicircular type depending on the manufacturing method. When considering the thermal print head itself as a unit, the thermal print head is classified as follows.

In the column 131, there is a thermal printing head consisting of a heating resistor and a wiring section that can be passed through the heating resistor. This is used as a small movable head in serial printers and the like. Second, there is a thermal print head that includes a heating resistor, a wiring section, a backflow prevention diode, and a matrix wiring. This is used for facsimiles and the like as a line-type head with paper widths such as No. 5 in row B and No. 4 in row B of the Japanese Industrial Standards. However, since this method performs time-division driving using matrix wiring, the printing noise is limited to around m5ec/line at most. Thirdly, there is a thermal print head comprising a heating resistor, a wiring section, and a driving integrated circuit (hereinafter referred to as IC). This is because the IC is mounted on the thermal print head.
Unlike the second thermal print head, it is possible to directly drive the heating resistor. Therefore, the third thermal print head is capable of high-speed printing of 1 to 2 m5ec/line, and its uses in printers and the like are expanding.

The third thermal print head will be explained below with reference to FIG. A thermal print head is constructed by arranging a heating resistor (2) and a plurality of ICs (3) on an insulating substrate (1) made of, for example, alumina. A common line (7) is connected between the ground pad (4) connected to each IC (3) and the ground pad terminal (5) formed on the insulating substrate (1) and electrically connected to the outside. ) and individual lines (6) for branching to each lCf3). Each IC (3) and the ground terminal (5) are electrically connected by this ground wiring. In addition, the ground wiring is made by vacuum evaporation method, sputtering method, etc.
It is formed of a vertical conductor film using film forming techniques such as a thick film formed by MIG, printing, etc., or a plating film.

Further, although not shown, a plurality of IC control signal lines and IC source lines are wired in two layers in a matrix between the IC (3) and the terminal group for external connection (10). ing. That is, for example, the Y direction sea individual line (6)
and IC system (I+11 (U: line) are formed on an insulating substrate, and an insulating layer is formed on this individual line (6) and the IC control signal line. (Two common lines (power line and tC power line are formed.Individual: ili (G) and a common line (power line, IC control signal line and IC power line are formed through openings provided in the insulating layer. electrically connected via.

By the way, the line head of type 5 in row A of the Japan Liang Standard requires a heating resistor sub-length of 216 vpm.

In this case, a resolution of 8 dots) and 7 mm requires 1728 heating resistors. Furthermore, the current mainstream of ICs is one that drives 32 dots with one element due to chip cost and other considerations. Therefore, the heating resistor sub-length that can be driven by one IC is 32 (dots) ÷ 8c dots/unit) = 4 (my
). That is, in the method of arranging ICs only on one side of the heat generating resistor array, the wiring density must be extremely increased or the size of the ICs must be extremely small. Increasing the wiring density increases manufacturing costs and is not realistic. Furthermore, methods for reducing the size of an IC are subject to certain limitations in terms of current carrying capacity and the size of bonding terminals, although this depends on the manufacturing method. Therefore, when arranging ICs on one side, a multilayer wiring method such as two-layer wiring is used. However, in order to further reduce the price of the thermal print head, a method was adopted in which the heating resistor row was placed in the center of the insulating substrate and the IC was placed on both sides of the heating resistor row, making the thin film wiring into a single layer using an alternating common type. This method uses a flexible tape 1 method to connect the isolated common electrodes (i.e., the common electrodes). 3. Unlike the second thermal print head, the third thermal print head generates heat at the junction between the common electrode and the flexible tape 3. They form a row parallel to the resistor array.For this reason, when the third thermal printing head is used, that is, when the thermal printing head and the thermal paper slide, the 1ω electrode and the flexible tape are External forces are applied to the joints.As a result, there is a risk that the flexible tape will separate from the common electrode since there are few joints between the common electrode and the flexible tape.Furthermore, when a thermal print head is used, the thermal print head itself generates heat. This heat causes thermal expansion of the insulating substrate and the flexible tape. Normally, the thermal expansion coefficients of the insulating substrate made of, for example, alumina and the flexible tape are different, so if the insulating substrate and the flexible tape undergo thermal expansion. , there is a risk that an unexpected external force will occur at the joint between the common electrode and the flexible tape, causing the common electrode and the flexible tape to become tangled.

Next, the contact point between the common electrode and the flexible tape will be described in more detail with reference to FIG. Figure 2 shows the absolute substrate (2
1) A cross-sectional view showing the bonding state between the common electrode (22) made of gold formed on the polyimide film e4) and the flexible tape (27) in which two pieces of copper are bonded together.

Note that the copper layer is sandwiched between a polymide film (2i) and a solder resist (26). The common electrode (221) made of copper and gold is bonded by heating, but since the fusion between copper and gold is poor, usually a common electrode (2201) with gold plating is used on the top of the common electrode (2201). In addition, tin plating (2501) is deposited on the copper (two pieces).This gold plating (2201) and sparrow plating (2501) are heated to form a mixture of gold and soot. By forming a eutectic, the flexible tape (27) and the common electrode (2) are bonded. However, as mentioned above, in the third thermal print head, the flexible tape (27) and the common electrode (2) are bonded. Since the number of points is small, if an external force is applied to the eutectic junction of gold and soot, the thin film will peel off, and the flexible tape (27
) and the common electrode t2 may peel off. Also,
In the step of joining the flexible tape (27) and the common electrode (2), the positioning of the flexible tape (27) and the common electrode (2) must be performed individually, which poses a problem of extremely low productivity.

[10th Object of the Invention] The present invention has been made in view of the above-mentioned problems, and provides a highly reliable thermal print head by using an isoelectric material in the tangent to the wiring circuit of the thermal print head. The purpose is to

[Four essentials of invention]

To achieve the above object, the present invention provides an electrocardioelectric body in which an insulating layer is formed on a wiring circuit, an opening is provided in the insulation layer, and the wiring circuit is electrically connected through the opening. By providing this, it becomes possible to complete the connection between the wiring circuit and the %;('i'm+ body.

[Embodiments of the invention]

The details of the thermal print head of the present invention will be explained below.

Note that the basic structure of the thermal print head on which the IC is mounted is the same as that shown in FIG. 1, so a detailed explanation will be omitted.

31st page 1 is a partially cutaway perspective view of an alternating common type thermal printing radar equipped with an IC.

In FIG. 3, a plurality of heating resistors (112) are arranged in a - row on an insulating substrate (110) made of alumina having a glaze layer (111) on its surface, and each heating resistor (
112) is connected to one end of a wiring circuit in which, for example, chromium and gold are sequentially laminated, that is, a first common electrode (114) group and a second common electrode (115) group.

Further, each heating resistor (112) is connected to the first common electrode (112).
14) and the second common electrode (115) (white portions of the common electrodes (114) and (115) in the figure) are connected in a one-to-one correspondence. This individual wiring is connected to a first common electrode (114) and a second common electrode (115).
) are connected to common leads (11401) and (11501) (shaded areas in the figure). First common electrode (11
4) The other end of the group and the second common electrode (115) group is a bonding pad (not shown), and the bonding wire (not shown) connects the first IC group (116a).
, (116b).

・, m2 IC group (117a), (117b)
, - terminals (not shown). In this example, the IC (116a).

(116b), (117a), (117b) One chip drives 32 dots, and the group consisting of two chips worth of heating resistors has one common 1σ E pole (114), (115)
It is connected to the. Also, IC (116a), (1
The back surfaces of 16b), (117a), and (117b) are grounded, and the thin film leads (
+8+, f19), and further connected to the signal line group (120) by wire bonding (row 1 not shown).
, jump (121) and connect the thin film ground electrode (12
3) is connected to (125).

IC (116a), (116b), (IL7a
), (117b) are supplied with power by thin eleven electrodes (122), (124) and IC (116a).
, (116b).

This is possible by connecting the (117a) and (117b) terminals with wire bonding (not shown). Furthermore, the signal line group (120), (121) of the clock (not shown) and shift register (not shown) Q7;
) is placed between these electrodes, and each IC (11
6a), (116b), (117a).

(117b) signal terminal and signal line group (120), (
121) by wire bonding.

A plurality of common electrodes (114) and (115), in which heating resistors (112) are grouped every 64 dots, that is, a common lead (
11401).

(11501) are electrically and electrically connected by a conductor, for example, an isoelectric wire (126) made of aluminum wire with a diameter of 0.5 mm. A common electrode (114) is connected to the lower part where the conductive wire (126) jumps via an insulating layer.
, (115) are formed. Common electrode (114)
The common lead (11401) is electrically connected to the conductive wire (126) through an opening (113a) provided in the disconnected layer. Also, the common lead (1) of the common electrode (115)
1501) is electrically connected to the conductive wire (126) via an opening (113b) provided in the insulating layer. Also, a common electrode (114).

(115) each common lead (11401),
(11501) and the conductive wire (126) are connected using an ultrasonic bonder. One end of the conductive wire (126) is connected to external extraction relay points (127) and (128). Note that this insulating layer uses solder resist as a common electrode (114
), (115) by screen printing.

In the thermal printing shown in FIG. 3, the width of the conductive wire (126) is not as wide as that of flexible tape, that is, even if the thermal paper slides on the thermal printing head, the area in contact with the thermal paper is small. Common electrodes (114), (115) due to external force
Each common lead (11401), (11501)
Peeling of the junction between the conductive wire (126) and the conductive wire (126) is prevented.

In addition, the insulating substrate (110) and the conductive wire (126) undergo thermal expansion due to the heat generated during use of the thermal print head shown in FIG. If a conductive line (126) is formed with a coefficient of compatibility, the common electrode (114) due to thermal expansion (-), (11
5) Peeling of the junction with the torpedo wire (126) is prevented.

That is, unlike a flexible tape, since the conductive wire (126) is made of a single material, it is easy to make the coefficient of thermal expansion substantially equal to the coefficient of thermal expansion of the insulating substrate (110).

Furthermore, the thermal printing head shown in FIG. 3 can be performed non-electrically and mechanically by forming, for example, a thick aluminum jumper wire as a conductor, such as electrocardiogram tk (126), by ultrasonic stitch bonding. The manufacturing process of the thermal print head is simplified, and a highly reliable and inexpensive thermal print head can be provided.

In this embodiment, the conductor is an IH wire, for example, an aluminum wire, but the conductor may be a metal rod or an electrocardiogram.
Needless to say, it is also possible to use methods such as . Furthermore, (2) the insulating substrate (110) shown in Fig. 3 is a single insulating substrate;
, (116b), (117a), (117
b) and a common electrode (114).

(115) need only be on the same main surface, and the insulating substrate (110) may be composed of a plurality of divided substrates.

〔Effect of the invention〕

By adopting the above-described configuration, the present invention prevents the bond between the wiring circuit and the conductor from peeling off due to force or external force caused by the difference in coefficient of thermal expansion between the insulating substrate and the conductor.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the basic configuration of a thermal print head.
FIG. 2 is an explanatory diagram illustrating the bonding state between the flexible tape and the common electrode, and FIG. 3 is a partially cutaway perspective view showing an embodiment of the thermal print head of the present invention. (1), (111)...Insulating substrate +22), (1
14), (1t5)...Common electrode (wiring circuit) (11
3a), (113b) ---Opening part (126)...
Conductive wire (conductor) Agent Patent attorney Noriyuki Chika (and 1 other person) f32 Figure 3 Figure 2/2

Claims (5)

[Claims] (1) A plurality of heating resistors formed on an insulating substrate,
An integrated circuit formed on the same main surface as the heating resistor of Mk, an integrated circuit formed on the same main surface as the heating resistor, and an integrated circuit formed on the same main surface as the heating resistor and the integrated circuit. In a thermal print head comprising at least a wiring circuit formed on the wiring circuit, an insulating layer is formed on the wiring circuit, an opening is provided in the insulation layer, and the wiring circuit is electrically connected through the opening. A thermal print head characterized by being provided with an electrically conductive material that connects to the surface. (2) The thermal print head according to claim 1, wherein the conductor is made of a conductive wire. (3) A part of the wiring circuit is a common electrode that electrically connects the plurality of heating resistors and the integrated circuit and electrically connects to the conductor through the 11 holes. A thermal print head according to claim 1, characterized in that: (4) The plurality of heating resistors are formed in a line to constitute a heating resistor row, the integrated circuit is formed on both sides of the heating resistor row, and on one side of the heating resistor row, a plurality of heating resistors are formed. forming a first integrated circuit group consisting of the integrated circuits; forming a second integrated circuit group consisting of a plurality of the integrated circuits on the other side of the heating resistor array; A first common electrode group in which the heat generating resistors connected to each other are connected to each other individually, and the heat generating resistors connected to the second integrated circuit group are fixed. A second common electrode group in which the heat generating resistors are individually connected together is a group of common electrodes provided on the insulating layer formed on the $1 common electrode group and the second common electrode group. 4. The thermal print head according to claim 1, wherein the thermal print head is electrically connected by the individual conductive wires through the apertures. (5) The individual common electrodes of the first common electrode group and the individual common frames of the second common electrode group cross each other on both sides of the heating resistor for each common electrode. A thermal print head according to claim 4, characterized in that: