US-12623467-B2 - Thermal print head

US12623467B2US 12623467 B2US12623467 B2US 12623467B2US-12623467-B2

Abstract

The present disclosure provides a thermal print head. The thermal print head includes: a substrate; a glaze layer, disposed on the substrate; and a wiring layer, disposed on the glaze layer. The wiring layer includes a plurality of bonding pads. The plurality of bonding pads are divided into a plurality of groups. Each of the plurality of groups includes a first bonding pad, a second bonding pad, a third bonding pad and a fourth bonding pad. A first group of the plurality of groups is adjacent to a second group of the plurality of groups along a first direction. The second bonding pad of the first group is located between a center of the first bonding pad of the first group and a center of the third bonding pad of the first group along the first direction.

Inventors

Yasuyuki Aritaki
Toshio Watanabe
Kazuya Nakakubo
TAKAMICHI OTANI

Assignees

ROHM CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20240216
Priority Date: 20230224

Claims (7)

1 . A thermal print head, comprising: a substrate; a glaze layer, disposed on the substrate; and a wiring layer, disposed on the glaze layer, wherein the wiring layer includes a plurality of bonding pads, the plurality of bonding pads are divided into a plurality of groups, each of the plurality of groups includes a first bonding pad, a second bonding pad, a third bonding pad and a fourth bonding pad, a first group of the plurality of groups is adjacent to a second group of the plurality of groups along a first direction, the second bonding pad of the first group is located between a center of the first bonding pad of the first group and a center of the third bonding pad of the first group along the first direction, the fourth bonding pad of the first group is located between the center of the third bonding pad of the first group and a center of the first bonding pad of the second group along the first direction, the third bonding pad of one of the plurality of groups is disposed between the first bonding pad, the second bonding pad, and the fourth bonding pad of the one of the plurality of groups along a second direction perpendicular to the first direction, and the first bonding pads of the plurality of groups are arranged to form a first row along the first direction, the third bonding pads of the plurality of groups are arranged to form a second row along the first direction, and the second bonding pads and the fourth bonding pads of the plurality of groups are arranged to form a third row along the first direction, wherein further the first row, the second row, and the third row are arranged on positions shifted from one another in the second direction.
2 . The thermal print head of claim 1 , wherein a thickness of the wiring layer is between about 3 μm and about 10 μm.
3 . The thermal print head of claim 2 , wherein a material of the wiring layer comprises silver.
4 . The thermal print head of claim 1 , wherein a pitch between two adjacent bonding pads of the plurality of bonding pads along the first direction is between about 30 μm and about 70 μm.
5 . The thermal print head of claim 4 , wherein a material of the wiring layer comprises silver.
6 . The thermal print head of claim 1 , wherein a material of the wiring layer comprises silver.
7 . A thermal print head, comprising: a substrate; a glaze layer, disposed on the substrate; and a wiring layer, disposed on the glaze layer, wherein the wiring layer includes bonding pads that are divided into groups, each of the groups includes a first bonding pad, a second bonding pad, a third bonding pad, and a fourth bonding pad, wherein wherein a first group of the groups is adjacent to a second group of the groups along a first direction; the second bonding pad of the first group is located between a center of the first bonding pad of the first group and a center of the third bonding pad of the first group along the first direction; the fourth bonding pad of the first group is located between the center of the third bonding pad of the first group and a center of the first bonding pad of the second group along the first direction; the third bonding pad of one of the groups is disposed between the first bonding pad, the second bonding pad, and the fourth bonding pad of the same group along a second direction perpendicular to the first direction; the first bonding pads of the groups are arranged to form a first row along the first direction, the third bonding pads of the groups are arranged in a position of a second row along the first direction, and the second bonding pads of the groups are arranged to form a third row along the first direction, wherein further the first row, the second row, and the third row are offset from one another in the second direction.

Description

TECHNICAL FIELD The present disclosure relates to a thermal print head. BACKGROUND For example, the Japanese Patent Publication No. 2019-98667 (patent publication 1) discloses a thermal print head. The thermal print head disclosed in patent document 1 includes a substrate, a glaze layer and a wiring layer. The glaze layer is disposed on the substrate. The wiring layer is disposed on the glaze layer. The wiring layer includes a plurality of first bonding pads and a plurality of second bonding pads. The plurality of first bonding pads are arranged along a first direction to form one row. The plurality of second bonding pads are arranged along the first direction to form one row. The row of the first bonding pads is located on a position shifted from the row of the second bonding pads in a second direction. The second direction is a direction perpendicular to the first direction. A lead wiring portion extends from the first bonding pads and the second bonding pads along the second direction. PRIOR ART DOCUMENT Patent Publication [Patent document 1] Japan Patent Publication No. 2019-98667 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a thermal print head 100. FIG. 2 is a cross-sectional view along a section line II-II in FIG. 1. FIG. 3 is a cross-sectional view along a section line III-III in FIG. 1. FIG. 4 is a cross-sectional view along a section line IV-IV in FIG. 1. FIG. 5 is an enlarged partial view of FIG. 1. FIG. 6 is manufacturing steps of the thermal print head 100. FIG. 7 is a cross-sectional view of glaze layer forming step S2. FIG. 8 is a cross-sectional view of metal layer forming step S3. FIG. 9 is a cross-sectional view of metal layer patterning step S4. FIG. 10 is a cross-sectional view of heat generator forming step S5. FIG. 11 is a cross-sectional view of protection glass forming step S6. FIG. 12 is an enlarged plan view of a thermal print head 100A. DETAILED DESCRIPTION OF THE EMBODIMENTS Details of the embodiments of the present disclosure are given with the accompanying drawings below. The same or equivalent parts are denoted by the same numerals or symbols in the accompanying drawings below, and the repeated description is omitted. A thermal print head of the embodiment is set to configured to be a thermal print head 100. (Configuration of Thermal Print Head 100) The configuration of the thermal print head 100 is described below. FIG. 1 shows a cross-sectional view of the thermal print head 100. In FIG. 1, the drawing of a protection glass 50 is omitted. FIG. 2 shows a cross-sectional view along a section line II-II in FIG. 1. FIG. 3 shows a cross-sectional view along a section line III-III in FIG. 1. FIG. 4 shows a cross-sectional view along a section line IV-IV in FIG. 1. FIG. 5 shows an enlarged partial view of FIG. 1. As shown in FIG. 1 to FIG. 5, the thermal print head 100 includes a substrate 10, a glaze layer 20, a wiring layer 30, a heat generator 40 and a protection glass 50. The substrate 10 has a first main surface 10a and a second main surface 10b. The first main surface 10a and the second main surface 10b are end surfaces of the substrate 10 in the thickness direction. The second main surface 10b is a surface opposite to the first main surface 10a. In a plan view (observed from the side of the first main surface 10a along a normal direction of the first main surface 10a), a lengthwise direction of the substrate 10 is set as a first direction DR1. A direction perpendicular to the first direction DR1 in the plan view is set as a second direction DR2. Two ends of the substrate 10 in the second direction DR2 are respectively set as a first end 10c and a second end 10d. The substrate 10 is formed of an insulating material. The substrate 10 is formed of, for example, ceramic. A material forming the substrate 10 is specifically, for example, aluminum oxide (Al2O3). The glaze layer 20 is disposed on the substrate 10. More specifically, the glaze layer 20 is disposed on the first main surface 10a. The glaze layer 20 is formed of an insulating material. A material forming the glaze layer 20 is specifically, for example, glass. The wiring layer 30 is disposed on the glaze layer 20. The wiring layer 30 includes a common electrode 31 and a plurality of individual electrodes 32. The common electrode 31 includes a body 31a and a plurality of protrusions 31b. The body 31a extends along the first direction DR1. The body 31a is located on the side of the first end 10c in the second direction DR2. That is to say, a distance between the first end 10c and the body 31a in the second direction DR2 is less than a distance between the second end 10d and the body 31a in the second direction DR2. The protrusions 31b protrude from an edge of the body 31a facing the side of the second end 10d along the second direction DR2. The plurality of protrusions 31b are arranged at intervals along the first direction DR1. Each of the individual electrodes 32 includes a front end 32a on one e