Heating FPC and processing method thereof

Abstract

The invention discloses a heating FPC (Flexible Printed Circuit) and a processing method thereof. Manganese-copper alloy with an extremely low resistance temperature coefficient is used as a heating body, and thermoplastic polyimide with an adhesive layer capable of resisting the temperature of 200 DEG C for a long time is used as an insulating material. And a browning treatment process is introduced during processing, micro-etching coarsening and conversion film treatment are performed on the manganin surface, and the peel strength between the manganin surface and a TPI adhesive film is improved, so that the problem of interlayer layering is thoroughly solved. According to the invention, through collaborative innovation of materials and processes, the resistance stability, the long-term heat-resistant reliability and the mechanical bonding strength of the heating FPC are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of flexible electric heating element technology, specifically to a heating FPC and its processing method. Background Technology

[0002] Currently, heating elements on the market generally use copper alloy heating elements with thermosetting polyimide film as the outer insulating protective layer, which is suitable for most heating elements that require precise temperature control, long-term heat resistance, and stable heat conduction.

[0003] Existing heating elements generally use constantan alloy. For example, the applicant's utility model patent application (CN201821818390.3) filed on November 6, 2018. Constantan alloy has a moderate resistivity (approximately 40-50 μΩ·cm) and a low temperature coefficient of resistivity (approximately ±20 × 10⁻⁶). -6 / ℃), which is not suitable for some devices that require extremely high resistance values ​​or long-term heating. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a heat-generating FPC and its processing method, so as to improve the resistivity of the heat-generating FPC, thereby improving the stability and safety of the heat-generating FPC.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A heating FPC includes a top thermoplastic polyimide film, a manganese copper heating element, and a bottom thermoplastic polyimide film laminated together, wherein the manganese copper heating element is made of manganese copper alloy material.

[0006] The manganese-copper alloy material comprises 68%–72% copper and 28%–32% manganese.

[0007] A method for processing the heat-generating FPC as described above, the method comprising the following steps: Step 1: Perform a roughening process: brown and bake the manganese copper heating element; Step 2: Press the manganese copper heating element with a thermoplastic polyimide film; Step 3: Create a graphic circuit on one side of the manganese copper heating element that is not covered with thermoplastic polyimide film to form the FPC body; Step 4: Perform secondary roughening treatment: Brown and bake the side of the FPC body that has been made with patterned circuits; Step 5: Press the side of the FPC body after browning treatment with another thermoplastic polyimide film.

[0008] The fabrication of the graphic circuit includes processes such as dry film lamination, exposure, development, etching, film removal, automatic optical inspection, and resistance measurement.

[0009] By adopting the above scheme, this invention uses a manganese-copper alloy with ultra-high resistance stability as the heating element material, replacing the traditional constantan alloy; simultaneously, it selects a thermoplastic polyimide film with a long-term temperature resistance of up to 200°C as the insulating layer, replacing the thermosetting polyimide film with a temperature resistance of only 105°C. Furthermore, this invention innovatively introduces a browning treatment process to improve the peel strength between the heating element and the thermosetting polyimide film, fundamentally avoiding delamination and bubble problems during subsequent use. Attached Figure Description

[0010] Figure 1 This is a flowchart of the processing of the present invention. Detailed Implementation

[0011] This invention discloses a heating FPC, which includes a top thermoplastic polyimide film, a manganese copper heating element, and a bottom thermoplastic polyimide film laminated together. The manganese copper heating element is made of a manganese copper alloy material, which includes 68%-72% copper and 28%-32% manganese.

[0012]

[0013] Table 1 As shown in Table 1, manganese-copper alloy materials possess ultra-high resistivity (approximately 40–60 μΩ·cm) and a low temperature coefficient of resistivity (approximately ±5 × 10⁻⁶). -6 ( / ℃). Therefore, the manganese copper heating element has a very obvious advantage in terms of resistance stability.

[0014] Furthermore, the insulating material adopted in this invention is thermoplastic polyimide film. Thermoplastic polyimide film is one of the organic polymer materials with the best comprehensive performance. Thermoplastic polyimide (TPI)** is a special member of the polyimide family. It can melt and flow when heated, can be processed, and has the characteristics of high temperature resistance, high insulation, and high strength.

[0015] like Figure 1 As shown, the heat-generating FPC processing method of the present invention is as follows: Step 1: Perform a roughening process: The manganese copper heating element is browned and baked, in which both sides of the manganese copper heating element are browned.

[0016] Step 2: Pressing a manganese copper heating element with a thermoplastic polyimide film; attaching a thermoplastic polyimide film to one side of the manganese copper heating element and pressing them together.

[0017] Step 3: Create the graphic circuitry to form the FPC body.

[0018] The pattern circuit is fabricated on one side of the manganese copper heating element that is not covered with thermoplastic polyimide film. The pattern circuit fabrication includes processes such as dry film application, exposure, development, etching, film removal, automatic optical inspection, and resistance measurement.

[0019] Step 4: Perform secondary roughening treatment: Brown and bake the side of the FPC body that has been made with graphic circuits.

[0020] Step 5: Pressing the FPC body with another thermoplastic polyimide film: Attach another thermoplastic polyimide film to one side of the FPC body that has undergone browning treatment, and then press them together.

[0021]

[0022] Table 2 In this invention, when the manganese copper heating element is bonded to the thermoplastic polyimide film, a pre-roughening treatment is first applied to the surface of the manganese copper alloy to improve the bonding strength of the thermoplastic polyimide film and enhance the overall heat resistance of the heated FPC.

[0023] In summary, this invention uses a manganese-copper alloy with ultra-high electrical resistance stability as the heating element material, replacing the traditional constantan alloy; simultaneously, it selects a thermoplastic polyimide film with a long-term temperature resistance of up to 200°C as the insulating layer, replacing the thermosetting polyimide film with a temperature resistance of only 105°C. Furthermore, this invention innovatively introduces a browning treatment process to improve the peel strength between the heating element and the thermosetting polyimide film, fundamentally avoiding delamination and bubble problems during subsequent use.

[0024] Therefore, through the synergistic improvement of the above materials and processes, this invention successfully manufactures a high-performance flexible heating element that combines extremely high resistance stability, excellent long-term heat resistance reliability, and outstanding mechanical bonding strength, significantly improving the overall performance and service life of the heating system.

[0025] The above description is merely an embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A heat-generating FPC, characterized in that: It includes a top layer of thermoplastic polyimide film, a manganese copper heating element, and a bottom layer of thermoplastic polyimide film pressed together, wherein the manganese copper heating element is made of manganese copper alloy material.

2. The heat-generating FPC according to claim 1, characterized in that: The manganese-copper alloy material comprises 68%–72% copper and 28%–32% manganese.

3. A method for processing the heat-generating FPC as described in claim 1 or 2, characterized in that: The method includes the following steps: Step 1: Perform a roughening process: brown and bake the manganese copper heating element; Step 2: Press the manganese copper heating element with a thermoplastic polyimide film; Step 3: Create a graphic circuit on one side of the manganese copper heating element that is not covered with thermoplastic polyimide film to form the FPC body; Step 4: Perform secondary roughening treatment: Brown and bake the side of the FPC body that has been made with patterned circuits; Step 5: Press the side of the FPC body after browning treatment with another thermoplastic polyimide film.

4. The processing method of a heat-generating FPC according to claim 3, characterized in that: The fabrication of the graphic circuit includes processes such as dry film lamination, exposure, development, etching, film removal, automatic optical inspection, and resistance measurement.

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