Substrate for thin film thermal printing head

Abstract

The utility model relates to the technical field of thermal printing head manufacturing, in particular to a substrate for a film thermal printing head, which is reasonable in structure, simple and convenient in process and capable of remarkably improving the product yield, and is characterized in that the coverage areas of a conductive protective layer and an insulating protective layer are overlapped; a PFA insulation barrier layer is further arranged between the electrode wire and the insulation protection layer, the length direction of the PFA insulation barrier layer is parallel to the heating resistor body, the width range of the PFA insulation barrier layer is 3-5 mm, and the PFA insulation barrier layer extends from the position 3-5 mm away from the heating resistor body to the bonding electrode at the tail end of the electrode wire. The problem of short circuit of the conductive hard protective layer and the electrode lead arranged on the insulating substrate in the substrate production process can be effectively avoided, and the yield of produced sheets is improved.

Description

Technical field:

[0001] The utility model relates to the technical field of thermal print head manufacturing, in particular to a substrate for a thin film thermal print head which has a reasonable structure and simple process and can significantly improve the product yield. Background technology:

[0002] The existing heating substrate for thin-film thermal print heads includes an insulating substrate with an amorphous glaze coating formed on the surface, a heating resistor layer is provided on the amorphous glaze coating, and a conductor layer covers the heating resistor layer. During the production process, the conductor layer is formed into electrode wires through photoengraving technology, and the resistor layer is formed into a plurality of heating resistors arranged along the main printing direction. Then, a non-conductive material whose main component is silicon is used to form an insulating thin film protective layer with a thickness of several thousand nm on the heating resistor and at least part of the electrode wires through magnetron sputtering. In order to enhance the wear resistance of the thermal print head and prevent static electricity generated by friction between the thermal print head and the printing consumables during the printing process, a conductive material is usually stacked on the insulating thin film protective layer to form a conductive hard protective layer of several thousand nm. For example, a composite material whose main components are carbon and silicon carbide can be used to form a conductive hard protective layer with high wear resistance. As shown in the attached figure Figure 1 As shown, in order to prevent the conductive hard protective layer from short-circuiting with the wire, the conductive hard protective layer is magnetron sputtered by using a two-layer shingle-shaped stacking method in which the width of the lower insulating film protective layer is at least greater than the width of the upper conductive hard protective layer. This production method is inefficient and requires much manual work.

[0003] In order to prevent short-circuit contact between the conductive hard protective layer and the electrode, the technical solution recorded in patent document CN115972778A mentions printing a low-temperature glass barrier layer on some electrodes. However, the bonding force between the low-temperature glass and the upper insulating protective layer causes the surface layer structure of the product to be easily peeled off, and the protective degree of the protective layer is reduced. In addition, glass sintering has the effect of increasing the resistance of the heating resistor on the substrate. Summary of the invention:

[0004] The utility model aims at the shortcomings and deficiencies in the prior art and proposes a substrate for a thin film thermal print head which has a reasonable structure, simple process and can significantly improve the product yield.

[0005] The utility model achieves this through the following measures:

[0006] A substrate for a thin film thermal print head is provided with an insulating substrate, a heat storage glaze layer is provided on the surface of the insulating substrate, a heating resistor and an electrode wire are provided on the surface of the heat storage glaze layer, a protective layer is provided on the upper surface of the heating resistor and the electrode wire, the protective layer includes an insulating protective layer and a conductive protective layer, the conductive protective layer is arranged on the insulating protective layer, and is characterized in that the conductive protective layer overlaps with the covering area of ​​the insulating protective layer, a PFA insulating barrier layer is further provided between the electrode wire and the insulating protective layer, the length direction of the PFA insulating barrier layer is parallel to the heating resistor, the width range of the PFA insulating barrier layer is 3-5 mm, and starts from 3-5 mm away from the heating resistor and extends to the bonding electrode at the end of the electrode wire.

[0007] The thickness of the PFA insulating barrier layer of the utility model is in the range of 0.5-2.0 μm, because the hilllock height is generally below 1 μm.

[0008] The PFA insulating barrier layer of the utility model is close to the bonding electrode side of the end of the electrode wire and extends to the outside of the protective layer to achieve insulation protection for the electrode wire area and effectively avoid short circuit between the conductive protective layer and the wire.

[0009] The utility model is also provided with a solder resist layer, which is arranged on the electrode wire on the surface of the insulating substrate, and is arranged near the bonding electrode at the end of the electrode wire, along the length direction of the heating resistor. The width of the solder resist layer covers the part of the PFA insulating barrier layer exposed to the outside of the protective layer, and covers a partial area of ​​the protective layer, which can further avoid the contact between the electrode wire and the conductive protective layer, and enhance the bonding effect of the PFA insulating barrier layer, the protective layer and the substrate.

[0010] The PFA insulating barrier layer of the utility model is manufactured by discharging and forming a film on the surface of a substrate using the PFA material as a cathode target, which is a prior art and will not be described in detail here.

[0011] Compared with the prior art, the utility model provides a PFA insulating barrier layer with a width of 3-5mm and a thickness of 0.5-2um between the insulating film protective layer and the electrode wire, thereby effectively avoiding the short circuit problem between the conductive hard protective layer and the electrode wire provided on the insulating substrate during the substrate production process, thereby improving the production yield. When the PFA insulating barrier layer is provided, the conductive protective layer does not need to be strictly arranged in a shingle-shaped stacking structure with the insulating protective layer, thereby significantly reducing the process complexity and being conducive to improving production efficiency. Description of the drawings:

[0012] Attached Figure 1 It is a cross-sectional view of a substrate for a thin film thermal print head in the prior art.

[0013] Attached Figure 2It is a cross-sectional view of the utility model.

[0014] Attached Figure 3 It is a top view of the substrate of the utility model.

[0015] Figure numerals: 10, insulating substrate; 20, heat storage base glaze layer; 30, substrate base glaze layer; 40, heating resistor; 50, wire electrode; 50a, bonding electrode; 60, insulating film protective layer; 70, conductive protective layer; 80, solder resist protective layer; 90; PFA insulating barrier layer. Specific implementation method:

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] Example:

[0018] This example provides a heating substrate for a sensitive print head, including an insulating substrate 10, the insulating substrate 10 is mainly sintered by aluminum oxide material, a substrate bottom glaze layer 30 is arranged in all areas of the insulating substrate 10, the thickness of the substrate bottom glaze layer after sintering is set in the range of 5-20 μm, and a heat storage bottom glaze layer 20 is fired in a partial area of ​​the upper surface of the substrate bottom glaze layer 30, the thickness of the heat storage bottom glaze layer 20 is 20-60 μm, and the width is 0.4 mm-1.0 mm;

[0019] A heating resistor layer is further formed on the substrate glaze layer 30, and the heating resistor layer has a thickness of 20 to 500 nm. It is patterned by photolithography and etching to form a heating resistor 40. On the surface of the heat storage glaze layer 20, the substrate glaze layer 30, and the heating resistor 40, a wire electrode layer with a thickness of 0.5 to 1 μm is formed by magnetron sputtering using a metal aluminum target. The wire electrode layer is patterned by photolithography and etching. After the patterning is completed, an electrode wire 50 and a bonding electrode 50a are formed on the wire electrode layer. The electrode wire 50 is connected to both ends of the heating resistor 40 (heating resistor layer) to form a heating resistor unit. The common electrode is used to connect to an external power supply, and the bonding electrode 50a is used to connect to an external logic control signal.

[0020] Sputtering the PFA target material by a sputtering method to form a PFA insulating barrier layer 90 with a thickness of 0.5 to 2 um in a set area;

[0021] An insulating protective layer 60 is formed on the surface of the heat storage base glaze 20, the substrate base glaze layer 30, the heating resistor 40 and the wire electrode layer 50, and the thickness of the insulating protective layer 60 is 3 to 8 μm. A conductive protective layer 70 is formed on the insulating protective layer, and the thickness of the conductive protective layer is 3 to 8 μm. A solder resist layer 80 is set on part of the PFA insulating barrier layer 90 and part of the conductive protective layer 70 by screen printing and curing process to serve as a supplementary protection for the protective layer.

[0022] Compared with the prior art, the utility model provides a PFA insulating barrier layer with a width of 3-5mm and a thickness of 0.5-2um between the insulating film protective layer and the electrode wire, thereby effectively avoiding the short circuit problem between the conductive hard protective layer and the electrode wire provided on the insulating substrate during the substrate production process, thereby improving the production yield. When the PFA insulating barrier layer is provided, the conductive protective layer does not need to be strictly arranged in a shingle-shaped stacking structure with the insulating protective layer, thereby significantly reducing the process complexity and being conducive to improving production efficiency.

Claims

1. A substrate for a thin film thermal print head, comprising an insulating substrate, a heat storage glaze layer on the surface of the insulating substrate, a heating resistor and an electrode wire on the surface of the heat storage glaze layer, a protective layer on the upper surface of the heating resistor and the electrode wire, the protective layer comprising an insulating protective layer and a conductive protective layer, the conductive protective layer being arranged on the insulating protective layer, characterized in that: The conductive protective layer overlaps with the insulating protective layer coverage area, and a PFA insulating barrier layer is also provided between the electrode wire and the insulating protective layer. The length direction of the PFA insulating barrier layer is parallel to the heating resistor. The width of the PFA insulating barrier layer is in the range of 3-5 mm, and starts at 3-5 mm away from the heating resistor and extends to the bonding electrode at the end of the electrode wire.

2. The thin film thermal print head substrate according to claim 1, characterized in that: The thickness of the PFA insulating barrier layer is in the range of 0.5-2.0 μm.

3. The thin film thermal print head substrate according to claim 1, characterized in that: The PFA insulating barrier layer is close to the bonding electrode side of the end of the electrode wire and extends to the outside of the protective layer.

4. The thin film thermal print head substrate according to claim 1, characterized in that: A solder resist layer is also provided, which is arranged on the electrode wire on the surface of the insulating substrate, and is arranged near the bonding electrode at the end of the electrode wire, along the length direction of the heating resistor. The width of the solder resist layer covers the portion of the PFA insulating barrier layer exposed to the outside of the protective layer, and covers a partial area of ​​the protective layer.

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