Thermal print head and method for manufacturing the same

Abstract

The present invention discloses a thermal print head, including a substrate, a heat storage layer, a resistive heating element, an electrode portion, a conductive layer, a driving IC and a protective layer. The heat storage layer is attached to the surface of the substrate, and the resistive heating element is arranged on the heat storage layer. The electrode portion is arranged on the heat storage layer, and the electrode portion includes a first electrode portion and a second electrode portion respectively arranged on both sides of the resistive heating element. The conductive layer is arranged on the outside of the heat storage layer, including a plurality of conductive strips arranged at intervals along the length direction of the substrate and connected to the first electrode portion, the resistive heating element and the second electrode portion in sequence. The driving IC is interconnected with the conductive layer by reverse soldering, and the protective layer is arranged on the outside of the conductive layer. The present invention also discloses a method for manufacturing the above-mentioned thermal print head. The present invention uses a circuit made of a metal that can form an alloy with solder to replace the precious metal in the thick film circuit, which has the characteristics of thick film with adjustable resistance value while reducing the manufacturing cost of the thermal print head. The driving IC uses flip-chip soldering to replace the existing gold wire soldering, and the soldering speed is fast.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal printing devices, and in particular to a thermal printing head and a manufacturing method thereof. Background Art

[0002] The thermal print head is the main component of a thermal printer. The thermal printer selectively heats the thermal paper at certain locations to produce the pattern. The heat is provided by a small electronic heater on the print head that contacts the thermal material. The heater schedule is logically controlled by the printer in the form of dots or bars, and when driven, a pattern corresponding to the heated element is produced on the thermal paper. The same logic circuit that controls the heated element also controls the paper feed, so that the pattern can be printed on the entire label or paper.

[0003] "Thick film" is a production process for thermal print heads. In the prior art, the circuit materials of the thick film process are mostly made of gold. Gold wires are used in the manufacture of integrated circuits and the connection between driver ICs and integrated circuits. Due to the high cost of gold, the manufacturing cost of the entire thermal print head becomes very high. At the same time, since the gold circuit and the driver IC cannot be directly welded by soldering, the driver IC is packaged by welding gold wires one by one. This welding method is not only costly, but also slow, inefficient, and has low output. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a thermal print head with low cost and high welding speed and a manufacturing method thereof, so as to solve the technical problems mentioned in the background technology that the existing thermal print head adopts high cost of precious metal circuit and low efficiency of driver IC packaging.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A thermal print head, comprising:

[0007] substrate.

[0008] The heat storage layer is attached to the surface of the substrate.

[0009] The resistance heating element is arranged on the heat storage layer and extends along the length direction of the substrate.

[0010] The electrode portion is arranged on the heat storage layer, and the electrode portion includes a first electrode portion and a second electrode portion which are respectively arranged on both sides of the resistive heating element and extend along the length direction of the substrate.

[0011] The conductive layer is arranged outside the heat storage layer, and the conductive layer includes a plurality of conductive strips which are arranged at intervals along the length direction of the substrate and are sequentially conductively connected to the first electrode portion, the resistive heating element, and the second electrode portion.

[0012] The driving IC is arranged along the length direction of the substrate and is interconnected with the conductive layer by reverse welding.

[0013] The protection layer is arranged outside the conductive layer and the driving IC.

[0014] In one embodiment, the conductive layer has a thickness of 0.1 um to 30 um, and is made of one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy.

[0015] In another embodiment, the conductive layer includes a first transfer layer, a conductor layer and a second transfer layer arranged in sequence from bottom to top.

[0016] The conductor layer has a thickness of 0.1 um to 30 um, and is made of one of tin, copper, tin alloy and copper alloy.

[0017] The thickness of the first transfer layer and the second transfer layer are both 0.1um-15um, and the material is one of titanium, nickel, chromium, aluminum, titanium alloy, nickel alloy, chromium alloy, and aluminum alloy.

[0018] Furthermore, the substrate is a ceramic substrate, the heat storage layer is made of glass glaze with a thickness of 10um to 500um, and the resistive heating element is a semi-cylinder with a radius of 0.1um to 12um, and is made of ruthenium or a ruthenium-based compound.

[0019] Furthermore, the first electrode portion and the second electrode portion are both made of silver.

[0020] Furthermore, the protective layer includes a wear-resistant insulating layer, a solder resist layer, a surface wear-resistant layer and a protective layer. The wear-resistant insulating layer is arranged on the outside of the conductive layer and completely covers the first electrode portion and the resistive heating element, the solder resist layer is arranged on the outside of the conductive layer and completely covers the second electrode portion, and the solder resist layer and the wear-resistant insulating layer extend in opposite directions and have overlapping portions. A welding groove for installing the driver IC is reserved on the solder resist layer, the surface wear-resistant layer is attached to the outside of the wear-resistant insulating layer and completely covers the wear-resistant insulating layer, and the protective layer is coated on the outside of the driver IC.

[0021] Preferably, the material of the wear-resistant insulating layer is epoxy resin, the material of the solder resist layer is green oil, the material of the surface wear-resistant layer is metal ceramic, and the material of the protective layer is epoxy resin.

[0022] The present invention also discloses a method for manufacturing the thermal print head, comprising the following steps:

[0023] S1. Apply a heat storage layer on the substrate and sinter it.

[0024] S2. A resistive heating element extending along the length direction of the substrate is formed on the surface of the heat storage layer through printing and sintering processes.

[0025] S3. Forming a first electrode portion and a second electrode portion extending along the length direction of the substrate on both sides of the resistive heating element on the surface of the heat storage layer by printing and sintering.

[0026] S4. A conductive layer is plated on the outer side of the heat storage layer to completely cover the first electrode portion, the resistive heating element and the second electrode portion, and the conductive layer is etched into a plurality of conductive strips spaced apart along the length direction of the substrate.

[0027] S5. Make a protective layer on the outside of the conductive layer and reserve a driver IC welding station. At the welding station, reverse solder a driver IC arranged along the length direction of the substrate and package it.

[0028] In one embodiment, the conductive layer has a thickness of 0.1 um to 30 um, and is made of one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy.

[0029] In another embodiment, the conductive layer includes a first transfer layer, a conductor layer and a second transfer layer arranged in sequence from bottom to top.

[0030] The conductor layer has a thickness of 0.1 um to 30 um, and is made of one of tin, copper, tin alloy and copper alloy.

[0031] The thickness of the first transfer layer and the second transfer layer are both 0.1um-15um, and the material is one of titanium, nickel, chromium, aluminum, titanium alloy, nickel alloy, chromium alloy, and aluminum alloy.

[0032] The present invention has the following beneficial effects: providing a thermal print head and a manufacturing method thereof, using a circuit made of a metal that can form an alloy with solder to replace the precious metal in the thick film circuit, while having the thick film adjustable resistance characteristic, reducing the manufacturing cost of the thermal print head, and using flip-chip welding for the driver IC to replace the existing gold wire welding, with fast welding speed and high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. 4 is a schematic diagram of the cross-sectional structure of the thermal print head of the first embodiment.

[0034] Figure 2 for Figure 1 A partial enlarged schematic diagram of part A.

[0035] Figure 3 for Figure 1 A partial enlarged schematic diagram of part B.

[0036] Figure 4 for Figure 1A partial enlarged schematic diagram of part C in the middle.

[0037] Figure 5 It is a schematic diagram of the cross-sectional structure of the thermal print head of the second embodiment.

[0038] Figure 6 for Figure 5 A partial enlarged schematic diagram of part D in the middle.

[0039] Figure 7 for Figure 5 A partial enlarged schematic diagram of part E in the middle.

[0040] Figure 8 for Figure 5 A partial enlarged schematic diagram of part F in the middle.

[0041] Fig. 9 for Figure 5 A partial enlarged schematic diagram of part G in the middle.

[0042] Explanation of main component symbols: 1. Substrate; 2. Heat storage layer; 3. Resistive heating element; 41. First electrode portion; 42. Second electrode portion; 5. Conductive layer; 51. First transfer layer; 52. Conductor layer; 53. Second transfer layer; 6. Driving IC; 70. Overlapping portion; 71. Wear-resistant insulating layer; 72. Solder resist layer; 720. Welding station; 73. Surface wear-resistant layer; 74. Protective layer. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0044] Embodiment 1

[0045] like Figure 1-4 As shown, a thermal print head includes a substrate 1, a heat storage layer 2, a resistance heating element 3, an electrode portion, a conductive layer 5, a driving IC 6 and a protective layer. The substrate 1 is preferably an alumina ceramic substrate, the heat storage layer 2 is made of glass glaze with a thickness of 10um to 500um, and the resistance heating element 3 is a semi-cylinder with a radius of 0.1um to 12um, and is made of ruthenium or a ruthenium compound.

[0046] The heat storage layer 2 is attached to the surface of the substrate 1, and the resistance heating element 3 is arranged on the heat storage layer 2 and extends along the length direction of the substrate 1. The electrode part is arranged on the heat storage layer 2, and the electrode part includes a first electrode part 41 and a second electrode part 42 which are respectively arranged on both sides of the resistance heating element 3 and extend along the length direction of the substrate 1. The first electrode part 41 and the second electrode part 42 are both made of silver.

[0047] The conductive layer 5 is arranged outside the heat storage layer 2, and the conductive layer 5 includes a plurality of conductive strips arranged at intervals along the length direction of the substrate 1 and connected to the first electrode portion 41, the resistance heating element 3, and the second electrode portion 42 in sequence. The thickness of the conductive layer 5 is 0.1um to 30um, and the material is one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy. The driver IC 6 is arranged along the length direction of the substrate 1 and is interconnected with the conductive layer 5 by reverse soldering.

[0048] The protective layer is arranged on the outside of the conductive layer 5 and the driver IC 6. The protective layer includes a wear-resistant insulating layer 71, a solder resist layer 72, a surface wear-resistant layer 73 and a protective layer 74. The wear-resistant insulating layer 71 is arranged on the outside of the conductive layer 5 and completely covers the first electrode portion 41 and the resistive heating element 3. The solder resist layer 72 is arranged on the outside of the conductive layer 5 and completely covers the second electrode portion 42. The solder resist layer 72 and the wear-resistant insulating layer 71 extend in opposite directions and have an overlapping portion 70. A welding station 720 for installing the driver IC 6 is reserved on the solder resist layer 72. The surface wear-resistant layer 73 is attached to the outside of the wear-resistant insulating layer 71 and completely covers the wear-resistant insulating layer 71. The protective layer 74 is coated on the outside of the driver IC 6. Preferably, the material of the wear-resistant insulating layer 71 is epoxy resin, the material of the solder resist layer 72 is green oil, the material of the surface wear-resistant layer 73 is metal ceramic, and the material of the protective layer 74 is epoxy resin.

[0049] The manufacturing method of the thermal print head comprises the following steps:

[0050] The first step is to fire a glass glaze layer with a thickness of 10um to 500um on the alumina ceramic substrate.

[0051] The second step is to form a semi-cylindrical resistive heating element 3 with a radius of 0.1 to 12 um on the surface of the glass glaze layer by printing and sintering ruthenium or ruthenium-based compounds.

[0052] In the third step, a first electrode portion 41 and a second electrode portion 42 extending along the length direction of the substrate 1 are formed by printing and sintering silver on both sides of the resistive heating element 3 on the surface of the glass glaze layer.

[0053] The fourth step is to coat a conductive layer 5 with a thickness of 0.1um to 30um on the outer side of the glass glaze layer by PVD process and completely cover the first electrode part 41, the resistive heating element 3 and the second electrode part 42. The conductive layer 5 is made of one of aluminum, nickel, chromium, aluminum alloy, nickel alloy and chromium alloy. A plurality of conductive strips are equidistantly spaced along the length direction of the alumina ceramic substrate and are etched on the conductive layer 5 by dry or wet etching.

[0054] Step 5: Plate a wear-resistant insulating layer 71 on one side of the outside of the conductive layer 5 to completely cover the first electrode portion 41 and the resistive heating element 3; apply a layer of green oil on the other side of the outside of the conductive layer 5 to completely cover the second electrode portion 42 and reserve a welding station 720 for the driver IC 6, with the green oil and the wear-resistant insulating layer 71 having an overlapping portion 70; plate a surface wear-resistant layer 73 on the outside of the wear-resistant insulating layer 71, with the end of the surface wear-resistant layer 73 connected to the green oil at the overlapping portion 70. At the reserved welding station 720, reverse solder a driver IC 6 arranged along the length direction of the alumina ceramic substrate and encapsulate it with epoxy resin.

[0055] In this embodiment, one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy is used as the material of the conductive layer 5. Since aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy can be easily plated on the surface of the glass glaze, there is no need to use a transfer layer to strengthen its bonding strength.

[0056] Embodiment 2

[0057] like Figure 5-9 As shown, the difference between this embodiment and the first embodiment is that the thickness of the conductive layer 5 is 0.1um to 30um, and the conductive layer 5 includes a first transfer layer 51, a conductor layer 52, and a second transfer layer 53 arranged from bottom to top. The thickness of the conductor layer 52 is 0.1um to 30um, and the material is one of tin, copper, tin alloy, and copper alloy. The thickness of the first transfer layer 51 and the second transfer layer 53 are both 0.1um to 15um, and the material is one of titanium, nickel, chromium, aluminum, titanium alloy, nickel alloy, chromium alloy, and aluminum alloy. The rest of the structure of this embodiment is the same as that of the first embodiment.

[0058] The manufacturing method of this embodiment differs from that of the first embodiment only in that: a first connection layer 51 with a thickness of 0.1um to 15um is firstly plated on the glass glaze layer, a conductor layer 52 with a thickness of 0.1nm to 30um is plated on the surface of the first transfer layer 51, and then a second connection layer 53 with a thickness of 0.1um to 15um is plated on the surface of the conductor layer 52. Finally, the first transfer layer 51, the conductor layer 52, and the second transfer layer 53 are etched to form a plurality of conductive strips. The remaining steps of the manufacturing method of this embodiment are the same as those of the first embodiment.

[0059] In this embodiment, one of tin, copper, tin alloy, and copper alloy is used as the material of the conductor layer 52. Since the adhesion of the above materials on the surface of the glass glaze is not strong, a first transfer layer 51 and a second transfer layer 53 are added to strengthen the metal bonding force of the conductor layer 52.

[0060] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A thermal print head, characterized in that: include: substrate; A heat storage layer is attached to the surface of the substrate; A resistance heating element is arranged on the heat storage layer and extends along the length direction of the substrate; An electrode portion, arranged on the heat storage layer, comprising a first electrode portion and a second electrode portion, respectively arranged on both sides of the resistive heating element and extending along the length direction of the substrate; A conductive layer is arranged outside the heat storage layer, and the conductive layer includes a plurality of conductive strips arranged at intervals along the length direction of the substrate and connected to the first electrode portion, the resistance heating element, and the second electrode portion in sequence; A driver IC is arranged along the length direction of the substrate and is interconnected with the conductive layer by reverse soldering; The protective layer is arranged on the outside of the conductive layer and the driver IC; the thickness of the conductive layer is 0.1um~30um, and the material is one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy; the conductive layer includes a first transfer layer, a conductor layer, and a second transfer layer arranged in sequence from bottom to top; the thickness of the conductor layer is 0.1um~30um, and the material is one of tin, copper, tin alloy, and copper alloy; the thickness of the first transfer layer and the second transfer layer are both 0.1um~15um, and the material is one of titanium, nickel, chromium, aluminum, titanium alloy, nickel alloy, chromium alloy, and aluminum alloy; the substrate is a ceramic substrate, the material of the heat storage layer is glass glaze with a thickness of 10um~500um, and the resistive heating element has a radius It is a semi-cylinder with a diameter of 0.1um to 12um, and its material is ruthenium or a ruthenium-based compound; the materials of the first electrode part and the second electrode part are both silver; the protective layer includes a wear-resistant insulating layer, a solder resist layer, a surface wear-resistant layer and a protective layer, the wear-resistant insulating layer is arranged on the outside of the conductive layer and completely covers the first electrode part and the resistive heating element, the solder resist layer is arranged on the outside of the conductive layer and completely covers the second electrode part, the solder resist layer and the wear-resistant insulating layer extend in opposite directions respectively and have overlapping parts, a solder resist layer is reserved with a welding groove for installing the driver IC, the surface wear-resistant layer is attached to the outside of the wear-resistant insulating layer and completely covers the wear-resistant insulating layer, and the protective layer is coated on the outside of the driver IC.

2. A thermal print head as claimed in claim 1, characterized in that: The material of the wear-resistant insulating layer is epoxy resin, the material of the solder resist layer is green oil, the material of the surface wear-resistant layer is metal ceramic, and the material of the protective layer is epoxy resin.

3. A method for manufacturing a thermal print head as claimed in claim 1 or 2, characterized in that: The steps include: S1, coating a heat storage layer on a substrate and sintering it; S2, forming a resistive heating element extending along the length direction of the substrate on the surface of the heat storage layer through printing and sintering processes; S3, forming a first electrode portion and a second electrode portion extending along the length direction of the substrate on both sides of the resistive heating element on the surface of the heat storage layer by printing and sintering respectively; S4, coating a conductive layer on the outer side of the heat storage layer to completely cover the first electrode portion, the resistance heating element and the second electrode portion, and etching the conductive layer into a plurality of conductive strips arranged at intervals along the length direction of the substrate; S5. Make a protective layer on the outside of the conductive layer and reserve a driver IC welding station. At the welding station, reverse solder a driver IC arranged along the length direction of the substrate and package it.

4. A method for manufacturing a thermal print head as claimed in claim 3, characterized in that: The thickness of the conductive layer is 0.1um-30um, and the material is one of aluminum, nickel, chromium, aluminum alloy, nickel alloy, and chromium alloy.

5. A method for manufacturing a thermal print head as claimed in claim 3, characterized in that: The conductive layer comprises a first switching layer, a conductor layer and a second switching layer which are arranged in sequence from bottom to top.

6. A method for manufacturing a thermal print head as claimed in claim 5, characterized in that: The conductor layer has a thickness of 0.1 um to 30 um and is made of one of tin, copper, tin alloy and copper alloy.

7. A method for manufacturing a thermal print head as claimed in claim 5, characterized in that: The thickness of the first transfer layer and the second transfer layer are both 0.1um-15um, and the material is one of titanium, nickel, chromium, aluminum, titanium alloy, nickel alloy, chromium alloy, and aluminum alloy.

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