A thermal printhead structure

Abstract

The utility model relates to thermal printer technical field, specifically disclose a thermal print head structure, wherein, a plurality of recessed structure is set up on glass glaze layer, creates mechanical anchorage point for conductive slurry, can lock conductive slurry physically in glass glaze layer, the anchor structure can provide strong shearing resistance and anti -pulling force when pad experiences severe hot -press welding high temperature impact and the cold -hot cycle of subsequent printer long -term work, prevent peeling, its structural integrity and electrical connection reliability get promotion, reduce production defective rate, and prolong the life, at the same time, the increased contact area makes thermal stress be distributed in greater area, and not concentrate on a line on flat interface, the three -dimensional structure of recessed structure itself also provides the tiny deformation space, can absorb and buffer a part of stress due to thermal expansion difference, avoid stress concentration and lead to cracking, enhance the heat -resistant capacity of pad in the process of hot -pressing FPC flat cable.

Description

Technical Field

[0001] This utility model relates to the field of thermal printer technology, and in particular to a thermal printhead structure. Background Technology

[0002] The thermal printhead structure is the core component of a thermal printer. Its working principle involves precisely controlling the instantaneous heating of a semiconductor heating element, causing a chemical reaction in the coating of the thermal paper to produce color, enabling the printing of text and images without ink or ribbon. The thermal printhead structure is primarily achieved by fabricating metal circuit patterns and heating resistors on a ceramic substrate. However, inherent defects on the ceramic substrate surface can lead to incompleteness in the metal circuitry. Therefore, a glass enamel layer is typically added to the circuit surface of the ceramic substrate to improve the integrity and stability of the circuitry. On the ceramic substrate surface, wires supplying power to the heating resistors extend to the short side of the substrate. The driving of each heating resistor is accomplished by an integrated C-MOS chip, which integrates key components such as shift registers and latches. Control signals for the C-MOS chip are generally connected to pads on the ceramic substrate via flexible cables such as FPC (Flexible Printed Circuit) or FFC (Flat Flexible Cable), thereby achieving effective control of the chip.

[0003] In the current manufacturing process of ceramic substrates, the metallization process is relatively complex. One major challenge lies in the mismatch between the thermal expansion coefficients of the ceramic substrate and the metal material used. In practical applications, lead-free solder paste is typically used as a medium to thermo-press the FPC cable onto the pads on the ceramic substrate. The pressing temperature during this process is generally controlled within the range of 240℃ to 250℃. For products requiring rework due to poor pressing performance, the pads undergo repeated heating. Due to the difference in thermal expansion coefficients between the ceramic substrate and the metal material, repeated heating can easily lead to pad detachment and electrical connection interruption. This not only affects the overall reliability of the product but also significantly shortens its lifespan.

[0004] Therefore, a thermal printhead structure is urgently needed to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a thermal printhead structure that can effectively improve the stability of pad connections and enhance the overall reliability and service life of the product.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This utility model provides a thermal printhead structure, including:

[0008] Ceramic substrate;

[0009] A glass glaze layer is disposed on the outer surface of one side of the ceramic substrate, and at least one groove structure is formed on the outer surface of the glass glaze layer. The groove structure is filled with and cured with conductive paste to form a conductive layer.

[0010] A heating element, the heating element comprising at least one heating resistor, and the heating element being disposed on the glass enamel layer;

[0011] The pads are disposed on the conductive layer;

[0012] A metal conductor layer electrically connected between the pad and the heating element;

[0013] The control unit is connected to the FPC cable, which is electrically connected between the control unit and the pad.

[0014] As a preferred technical solution for the above-mentioned thermal printhead structure, the groove width of the groove structure ranges from 0.1mm to 0.5mm.

[0015] As a preferred technical solution for the above-mentioned thermal printhead structure, the groove depth of the groove structure ranges from 0.1mm to 0.3mm.

[0016] As a preferred technical solution for the above-mentioned thermal printhead structure, the groove structure is formed on the surface of the glass enamel layer by etching or laser drilling.

[0017] As a preferred technical solution for the above-mentioned thermal printhead structure, the conductive paste is solidified and filled into the groove structure by screen printing and high-temperature sintering.

[0018] As a preferred technical solution for the above-mentioned thermal printhead structure, the conductive paste is made of metal material.

[0019] As a preferred technical solution for the above-mentioned thermal printhead structure, the top surface of the conductive layer is not lower than the upper surface of the glass enamel layer.

[0020] As a preferred embodiment of the above-mentioned thermal printhead structure, the groove structure is elongated, and both ends of the opening contour of the groove structure on the surface of the glass enamel layer extend beyond the edge of the pad.

[0021] As a preferred technical solution of the above-mentioned thermal printhead structure, the distances between the two end contour lines along the length direction of the groove structure and the edge contour lines of the corresponding pads are a and b, respectively, where a and b satisfy: 1mm≤a≤10mm, 1mm≤b≤10mm.

[0022] As a preferred technical solution of the above-mentioned thermal printhead structure, a chamfered or arc-shaped transition structure is formed between the sidewall and the bottom surface inside the groove structure.

[0023] The beneficial effects of this utility model are as follows:

[0024] This utility model provides a thermal printhead structure, which includes: a ceramic substrate, a glass glaze layer, a heating element, solder pads, a metal wire layer, a control unit, and an FPC cable. The glass glaze layer is disposed on the outer surface of one side of the ceramic substrate, and at least one groove structure is formed on the outer surface of the glass glaze layer. The groove structure is filled with and cured with conductive paste to form a conductive layer. The heating element includes at least one heating resistor and is disposed on the glass glaze layer. The solder pads are disposed on the conductive layer. The metal wire layer is electrically connected between the solder pads and the heating element. The FPC cable is electrically connected between the control unit and the solder pads. This design, with multiple grooves on the glass enamel layer, creates mechanical anchoring points for the conductive paste, significantly increasing the contact surface area and engagement depth between the conductive paste and the glass enamel layer. This groove anchoring structure further physically locks the conductive paste within the glass enamel layer. When the pads undergo the harsh high-temperature impact of hot-press welding and the subsequent thermal cycles generated by long-term printer operation, the anchoring structure provides strong shear and pull-out resistance, preventing peeling. Its structural integrity and electrical connection reliability are significantly improved, reducing production defect rates and greatly extending the printhead's lifespan under harsh conditions. Simultaneously, the increased contact area allows thermal stress to be distributed over a larger area, rather than concentrated on a single line on a flat interface. The three-dimensional structure of the grooves also provides a small deformation space, absorbing and buffering some of the stress generated by thermal expansion differences, preventing stress concentration and cracking. This effectively enhances the heat resistance of the pads during the hot-pressing of the FPC cable. Attached Figure Description

[0025] Figure 1 Schematic diagram of the thermal printhead structure provided by this utility model Figure 1 ;

[0026] Figure 2 Schematic diagram of the thermal printhead structure provided by this utility model Figure 2 ;

[0027] Figure 3 Partial structural diagram of the thermal printhead structure provided by this utility model Figure 1 ;

[0028] Figure 4 Partial structural diagram of the thermal printhead structure provided by this utility model Figure 2 .

[0029] in:

[0030] 1. Ceramic substrate; 2. Glass glaze layer; 3. Groove structure; 4. Conductive paste; 5. Solder pads; 6. Metal conductor layer; 7. Control unit; 8. FPC cable. Detailed Implementation

[0031] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0032] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0033] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0034] Unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" of a second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] like Figures 1 to 4 As shown, this embodiment provides a thermal printhead structure, which includes: a ceramic substrate 1, a glass glaze layer 2, a heating element, a pad 5, a metal wire layer 6, a control unit 7, and an FPC cable 8. The glass glaze layer 2 is disposed on the outer surface of one side of the ceramic substrate 1, and at least one groove structure 3 is formed on the outer surface of the glass glaze layer 2. The groove structure 3 is filled with and cured with conductive paste 4 to form a conductive layer. The heating element includes at least one heating resistor and is disposed on the glass glaze layer 2. The pad 5 is disposed on the conductive layer. The metal wire layer 6 is electrically connected between the pad 5 and the heating element. The FPC cable 8 is electrically connected between the control unit 7 and the pad 5. This design creates multiple groove structures 3 on the glass enamel layer 2, providing mechanical anchoring points for the conductive paste 4. This significantly increases the contact surface area and engagement depth between the conductive paste 4 and the glass enamel layer 2. Through this groove anchoring structure design, the conductive paste 4 can be physically locked into the glass enamel layer 2. When the pad 5 undergoes the harsh high-temperature impact of hot-press welding and the subsequent hot-cold cycles generated by long-term printer operation, the anchoring structure provides strong shear and pull-out resistance, preventing peeling. Its structural integrity and electrical connection reliability are significantly improved, reducing the production defect rate and greatly extending the printhead's lifespan under harsh conditions. Simultaneously, the increased contact area allows thermal stress to be distributed over a larger area, rather than concentrated on a single line on a flat interface. The three-dimensional structure of the groove structure 3 itself provides a small deformation space, which can absorb and buffer some of the stress generated by thermal expansion differences, preventing stress concentration and cracking. This achieves stress dispersion and buffering, effectively enhancing the heat resistance of the pad 5 during the hot-pressing of the FPC cable 8.

[0037] Specifically, this embodiment provides the following technical solution by way of example: the groove width of the groove structure 3 is in the range of 0.1mm to 0.5mm, and the groove depth of the groove structure 3 is in the range of 0.1mm to 0.3mm.

[0038] Optionally, the groove structure 3 is formed on the surface of the glass enamel layer 2 by etching or laser drilling. This configuration allows for the fabrication of highly controllable micro-anchoring structures in shape and size on the sintered and cured dense glass enamel layer 2 using a precision subtractive manufacturing method of "forming first, then filling." This process not only achieves micron-level precision with clear contours and uniform depth of the groove structure 3, ensuring consistency in mass production, but also provides a robust mechanical interlocking interface for the subsequent filling of the conductive paste 4 by forming a cavity with smooth sidewalls and a designable rounded transition, thereby greatly enhancing the bonding strength and thermal stress resistance of the pads 5.

[0039] Optionally, the conductive paste 4 is cured and filled into the groove structure 3 by screen printing and high-temperature sintering (150℃-850℃). In this configuration, the conductive paste 4 is filled and covered into the groove structure 3 by methods such as screen printing, followed by high-temperature sintering. This causes the organic solvents in the conductive paste 4 to evaporate, the metal particles to melt and bond, and the paste to the glass glaze layer 2. During the sintering process, the metal particles and the glass undergo chemical reactions and physical bonding on the sidewalls and bottom of the groove structure 3, forming a stronger and more three-dimensional bonding interface than planar bonding.

[0040] Optionally, the conductive paste 4 is made of a metallic material.

[0041] It should be noted that in actual processing, a groove structure 3 needs to be formed on the glass glaze layer 2 of the ceramic substrate 1 by etching or laser drilling. Then, conductive paste 4 is printed on the groove structure 3 by screen printing. Subsequently, the conductive paste 4 is sintered by sintering (generally 150℃-850℃) to ensure that the groove structure 3 is completely filled with conductive paste 4.

[0042] Optionally, the top surface of the conductive layer is not lower than the upper surface of the glass enamel layer 2. This arrangement ensures that the conductive paste 4 is completely filled within the groove structure 3, thereby guaranteeing the maximum anchoring contact area and mechanical strength. It also ensures that the conductive layer can effectively support the pads 5 upwards and provides a reliable, flat or raised foundation for subsequent connections, avoiding connection voids or weak points due to insufficient filling.

[0043] Optionally, the groove structure 3 is elongated, and both ends of the opening contour of the groove structure 3 on the surface of the glass glaze layer 2 extend beyond the edge of the pad 5.

[0044] Optionally, the distances between the two end contour lines along the length of the groove structure 3 and the edge contour lines of the corresponding pads 5 are a and b, respectively, where a and b satisfy: 1mm≤a≤10mm, 1mm≤b≤10mm.

[0045] Optionally, a chamfered or arc-shaped transition structure is formed between the sidewall and the bottom surface inside the groove structure 3. This design effectively eliminates sharp stress concentration points, resulting in a more uniform and gentle internal stress distribution in the conductive paste 4 during filling and sintering curing, as well as during subsequent heating of the product.

[0046] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A thermal printhead structure, characterized in that, include: Ceramic substrate (1); A glass glaze layer (2) is disposed on the outer surface of one side of the ceramic substrate (1), and at least one groove structure (3) is provided on the outer surface of the glass glaze layer (2). The groove structure (3) is filled with and cured with conductive paste (4) to form a conductive layer. A heating element comprising at least one heating resistor, and the heating element being disposed on the glass enamel layer (2); Pads (5) are disposed on the conductive layer; A metal conductor layer (6) is electrically connected between the pad (5) and the heating element; The control unit (7) and the FPC cable (8) are electrically connected between the control unit (7) and the pad (5).

2. The thermal printhead structure according to claim 1, characterized in that, The groove width of the groove structure (3) ranges from 0.1 mm to 0.5 mm.

3. The thermal printhead structure according to claim 2, characterized in that, The groove depth of the groove structure (3) ranges from 0.1 mm to 0.3 mm.

4. The thermal printhead structure according to claim 1, characterized in that, The groove structure (3) is formed on the surface of the glass glaze layer (2) by etching or laser drilling.

5. The thermal printhead structure according to claim 1, characterized in that, The conductive paste (4) is solidified and filled into the groove structure (3) by screen printing and high-temperature sintering.

6. The thermal printhead structure according to claim 5, characterized in that, The conductive paste (4) is made of metallic materials.

7. The thermal printhead structure according to any one of claims 1-6, characterized in that, The top surface of the conductive layer is not lower than the upper surface of the glass glaze layer (2).

8. The thermal printhead structure according to any one of claims 1-6, characterized in that, The groove structure (3) is elongated, and both ends of the opening contour of the groove structure (3) on the surface of the glass glaze layer (2) extend beyond the edge of the pad (5).

9. The thermal printhead structure according to claim 8, characterized in that, The distances between the two end contour lines along the length direction of the groove structure (3) and the edge contour lines of the corresponding pads (5) are a and b, respectively, where a and b satisfy: 1mm≤a≤10mm, 1mm≤b≤10mm.

10. The thermal printhead structure according to any one of claims 1-6, characterized in that, The groove structure (3) has a chamfered or arc-shaped transition structure between the sidewall and the bottom surface.

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