JP2605077Y2 - Thermal print head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head, and more particularly to an improvement in a wiring portion of a head substrate.

[0002]

2. Description of the Related Art A thermal print head is used for recording characters and the like on thermal recording paper. Generally, a thermal print head is formed by forming a pair of electrodes on an insulating substrate, for example, a glazed ceramic substrate. A heating resistor is electrically connected between the electrodes. When recording is performed, a voltage is applied to the heating resistor between the two electrodes via a driving element to cause the heating resistor to generate heat, and the heat is applied to the thermosensitive recording paper. Thermal recording is performed according to the heat generation.

FIG. 3 is a sectional view of a main part of a general thermal print head. In FIG. 3, a head substrate 2 made of a glazed ceramic plate is fixed on a heat sink 1 with an adhesive or the like. A heating resistor 3 is formed on the head substrate 2, and a wiring pattern constituting the electrodes for supplying electricity to the heating resistor 3 is provided. Further, on the heat radiating plate 1, a driving element 4 for driving the heating resistor 3 is mounted, and a printed wiring board 5 provided with a wiring pattern for connecting to an external circuit is fixed. The drive element 4, for example, an electrode of a drive IC is connected to a connection pad of a corresponding wiring pattern and a gold wire 6,
7 is formed by wire bonding.

FIG. 2 is a plan view of a main part of the head substrate 2 on which the heating resistor 3 and the electrode pattern are formed. In FIG. 2, the head substrate 2 is formed using a glazed ceramic substrate, and includes the heating resistor 3 and a comb-shaped electrode 8 a for supplying a voltage to the heating resistor 3 on the head substrate 2. An individual electrode 9 to be wire-bonded to the common electrode 8 and the driving element 4 (FIG. 3) is formed. The output pad of the drive element 4 is wire-bonded to the bonding pad portion 10 of the individual electrode 9 with the wire 6 (FIG. 3).

Incidentally, the conventional head substrate 2 shown in FIG.
Is formed of a glazed ceramic substrate as described above. This substrate is formed by forming a slit of a predetermined depth by a laser scribe or the like on a glazed ceramic plate having a predetermined area, and forming a predetermined size along the slit. Divided into When the ceramic plate is divided along the slits, chipping 12 such as cracks and burrs 13 are generated in the slit division side 11 as shown in FIG. In particular, when the chipping 12 occurs on the slit division side 11, the glaze layer on the surface of the substrate is peeled off, and large peeling occurs.

Therefore, in order to avoid the effect of chipping 12 generated on the slit division side 11 of the glazed ceramic substrate, the electrode pattern constituting the individual electrode 9 as shown in FIG. And formed inside the divided side. When the electrode pattern 9 is formed in consideration of the chipping allowance W2 in this way, even if chipping occurs and peeling of the glaze layer on the surface progresses, it is possible to prevent peeling to some extent at the electrode pattern 9, but this electrode The vicinity of the end of the pattern 9 is a place where the pad portion 10 of wire bonding is formed, which becomes a factor of lacking reliability of wire bonding. Further, the size of the substrate must be increased by an amount corresponding to the chipping allowance W2, which does not lead to a reduction in the size of the thermal print head.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention reduces the chipping margin W2 and prevents the progress of peeling of the glaze layer due to chipping, thereby reducing chipping failure of the electrode pattern to the bonding pad portion. The present invention provides a head substrate for a thermal print head.

[0008]

The present invention takes advantage of the fact that the electrode pattern can stop the progress of peeling of the glaze layer due to chipping to a certain extent, by providing a discard pattern at the chipping margin to prevent chipping invasion. It is characterized in that it is suppressed.

[0009]

FIG. 1 is a plan view of a main part of a head substrate according to the present invention. The components having the same functions as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the region of the chipping margin W1 of the individual electrode 9 including the pad portion 10 to be wire-bonded to the output pad of the driving element 4, the discard pattern 14 is extended on the head substrate 2 by extending to the pad portion 10 of the pattern of the individual electrode 9. Formed. Then, a cutout 15 is provided as a mark in the pattern in order to identify the discarded pattern 14 and the pad portion 10 which is a wire bonding region and define the wire bonding region.
The formation of the notch 15 allows the wire bonding area
Identification is easy, and even if the notch 15 is deep,
Turn 14 is enough to prevent the chipping invasion
it can.

[0010]

By extending the discard pattern 14 on the individual electrode in this way, it is possible to suppress chipping invasion in this discard pattern portion. As a result, chipping defects can be reduced, and the production yield of the thermal print head is improved. Further, the chipping margin W1 can be made shorter than the conventional chipping margin W2, so that the size of the head substrate and the size of the structure of the thermal print head can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of the head substrate of the present invention.

FIG. 2 is a plan view of a main part of a conventional head substrate.

FIG. 3 is a sectional view of a main part of the thermal print head.

FIG. 4 is a perspective view of a glazed ceramic substrate divided into slits.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat sink 2 Head board 3 Heating resistor 8 Common electrode 9 Individual electrode 10 Individual electrode connection pad 14 Discard pattern for prevention of chipping invasion 15 Cut part for defining wire bonding area W1 Chipping margin

Claims (1)

(57) [Scope of request for utility model registration] A glazed device comprising: a radiating plate; and an individual electrode provided on the radiating plate, provided with a heating resistor on a surface thereof, and provided with a connection pad for energizing the heating resistor. a head substrate made of ceramics, and an insulating substrate provided with a driving element for driving the heating resistors, the thermal print head comprising the said connecting pads the driving element by wire bonding, connection pads of the individual electrodes To form a chipping invasion prevention discard pattern in the chipping margin area of the head substrate , and further comprises the connection pad and the discard pattern.
A thermal printhead, characterized in that it has a cutout for defining a pattern .