Protective film pasting positioning method for high-temperature-resistant circuit board

Abstract

The invention relates to a protective film pasting positioning method for a high-temperature-resistant circuit board, and the method comprises the following steps: S1, preparing a to-be-pasted copper-clad plate with process edges on the periphery, and preparing a cut protective film; s2, a fixing point is selected on the process edge of the copper-clad plate, a copper layer is removed at the position of the fixing point, the insulating layer is exposed at the position of the fixing point through windowing of the copper layer, and the exposed insulating layer area at the position of the fixing point is a base material bonding area; s3, overlapping and covering the copper-clad plate with a protective film, enabling the protective film at the fixed point to be in direct contact with the substrate bonding area, and performing thermal compression bonding on the protective film at the fixed point and the substrate bonding area by using thermal bonding equipment, so that the protective film is aligned and fixed through the fixed point; and S4, performing thermal compression bonding on the protective film and the FPC circuit board to be subjected to film pasting by using thermal lamination equipment to obtain the FPC circuit board subjected to film pasting.

Description

Technical Field

[0001] The invention relates to the technical field of flexible circuit board preparation, and in particular to a protective film laminating and positioning method for a high temperature resistant circuit board. Background Art

[0002] Flexible circuit boards are increasingly widely used in the electronics industry due to their excellent performance. The production process of flexible circuit boards includes multiple processes, including the lamination process after dry film lamination, alignment exposure, development, etching, and automatic optical inspection. In order to insulate and protect the devices and circuits on the surface of the circuit board products from oxidation, a special circuit board protective film is required for lamination, that is, a layer of protective film is covered on the copper foil circuit. After lamination, lamination is performed. At present, the lamination process of flexible circuit boards needs to be completed purely manually, that is, the protective film needs to be cut in advance according to the size of the board, and then manually pasted.

[0003] For some circuit board products used in devices that need to be used in high temperature environments, the high temperature resistance requirements for the circuit board products are relatively high. For example, high-end electronic cigarettes, large shield machines, photolithography machines, etc., the quality requirements for circuit boards are very high. Among them, the products are required to be able to maintain a certain period of time and maintain basic performance in a relatively high temperature environment. The Tg value of ordinary FPC protective films is low. The use of such low Tg value protective films cannot meet the requirements of high temperature working environments for circuit board products. If the circuit board is to meet the high performance requirements of high reliability and high temperature resistance, a high Tg protective film is required.

[0004] Before attaching the protective film to the circuit surface, the protective film must be covered on the circuit board surface for fixing, and then the protective film can be attached to prevent displacement during attachment. However, compared with ordinary FPC protective films, the existing methods for fixing such high Tg value protective films on the circuit board have certain defects, such as poor fixing effect, easy damage to the circuit board product during fixing, or the risk of damaging the flatness of the steel plate for lamination identification.

[0005] The prior art also discloses some methods for fixing the protective film, including applying glue for bonding and fixing, using staples for mechanical fixing, etc. However, in the process of using the above-mentioned prior art to position and fix the protective film of the flexible circuit board, there are the following problems: (1) During the glue coating process, the glue is easy to contaminate the product circuit area, and the glue needs to be cured, which affects the quality of the finished product and increases the process and cost; (2) A stapler is used to fix the protective film and the FPC together, but the stapler used in this method is made of steel, which has the risk of damaging the flatness of the steel plate for laminated identification. The laminated steel plate has a very high requirement for flatness. The stapler damages the flatness of the steel plate. The steel plate with insufficient flatness will affect the quality of the finished circuit board, which is particularly prone to defective rates for products with high requirements for circuit board quality. Summary of the invention

[0006] Based on this, it is necessary to provide a method for positioning a protective film for a high temperature resistant circuit board.

[0007] The embodiment of the present invention provides a method for positioning a protective film of a high temperature resistant circuit board, comprising the following steps:

[0008] S1. Prepare a copper-clad laminate with process edges on all four sides and a cut protective film;

[0009] S2, selecting a fixed point on the process edge of the copper clad laminate, removing the copper layer at the position of the fixed point, so that the insulating layer is exposed through the copper layer window at the position of the fixed point, and the exposed insulating layer area at the position of the fixed point is the substrate bonding area;

[0010] S3, superimposing the protective film on the copper-clad laminate, so that the protective film at the fixed point is in direct contact with the substrate bonding area, and using a thermal bonding device to perform thermal compression bonding between the protective film at the fixed point and the substrate bonding area, so that the protective film is aligned and fixed through the fixed point;

[0011] S4, using a thermal bonding device to thermally press the protective film and the FPC circuit board to be bonded, to obtain the bonded FPC circuit board.

[0012] Preferably, the protective film is a thermoplastic PI film, and the Tg of the protective film is > 225°C.

[0013] Preferably, the material of the protective film is thermoplastic polyimide, and the Tg value of the protective film is 233°C.

[0014] Preferably, the number of the fixed points is an even number, so that any of the fixed points has corresponding symmetrical points on the four edges of the FPC circuit board to be laminated. The process edges include a first process edge, a second process edge, a third process edge and a fourth process edge, the first process edge, the second process edge, the third process edge and the fourth process edge are respectively located on the four edges of the copper clad board, the first process edge is symmetrical with the third process edge, the second process edge is symmetrical with the fourth process edge, and the fixed points are all located on the first process edge and the third process edge; or, the fixed points are all located on the second process edge and the fourth process edge.

[0015] Preferably, the number of the fixing points is 6 or 8.

[0016] Preferably, the thermal bonding device is an electric soldering iron.

[0017] Preferably, the operating temperature of the electric soldering iron is 320-360°C, and the operating temperature of the electric soldering iron is 350°C.

[0018] Preferably, the electric soldering iron stays on the protective film for 2-4 seconds.

[0019] Preferably, the copper clad laminate is a double-sided copper clad laminate.

[0020] Preferably, the copper-clad board comprises an insulating layer, a first surface of the insulating layer is provided with a first copper-clad layer, and a second surface of the insulating layer is provided with a second copper-clad layer.

[0021] The present invention provides a film laminating method based on a high temperature resistant protective film, which realizes effective bonding and fixing of the high temperature resistant high Tg protective film and FPC, thereby avoiding the problems of low yield rate, damage to preparation equipment, inaccurate laminating and positioning of the protective film caused by the existing film laminating method, and obtaining a high-quality high temperature resistant FPC circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other purposes, features and advantages of the present invention will become more clear by more specific description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals indicate the same parts in all the accompanying drawings, and the accompanying drawings are not deliberately scaled to the actual size, and the focus is on illustrating the main purpose of the present invention.

[0023] Figure 1 A schematic diagram of a copper clad laminate according to a preferred embodiment of the present invention;

[0024] Copper clad laminate 1; product area 100; fixing point 2; first process edge 31; second process edge 32; third process edge 33; fourth process edge 34. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. The terms used in the specification herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] like Figure 1 As shown, the present invention provides a method for positioning a protective film for a high temperature resistant circuit board, comprising the following steps:

[0028] S1. Prepare a copper-clad laminate 1 with process edges on all sides to be laminated, and prepare a cut high-temperature resistant protective film; the high-temperature resistant protective film refers to a film with Tg>200°C; wherein the copper-clad laminate 1 includes a process area and a product area 100, the process area is the process edge, etc., and the product area is the circuit board product area.

[0029] S2, selecting a fixed point 2 on the process edge of the copper clad laminate 1, removing the copper layer at the position of the fixed point 2, so that the insulating layer is exposed through the copper layer window at the position of the fixed point 2, and the exposed insulating layer area at the position of the fixed point 2 is the substrate bonding area;

[0030] S3, superimposing the protective film on the copper clad laminate 1, so that the protective film at the fixing point 2 is in direct contact with the substrate bonding area, and using a thermal bonding device to perform thermal compression bonding between the protective film at the fixing point 2 and the substrate bonding area, so that the protective film is aligned and fixed through the fixing point 2;

[0031] S4, using a thermal bonding device to thermally press the protective film and the FPC circuit board to be bonded, to obtain the bonded FPC circuit board.

[0032] The positioning method of the present invention is simple and easy to operate. It will not contaminate the circuit board during the process of fixing the protective film, nor will it cause mechanical damage to the operating desktop. It avoids the defect that the stapler in the prior art damages the flatness of the steel plate, and the steel plate with insufficient flatness will cause the quality of the finished circuit board to be affected. It also solves the risk of product defect rate caused by damage to the flatness of the steel plate. Moreover, by setting the fixed point 2, the protective film is tensioned and attached to the flexible circuit board, so that the protective film remains in a taut state when attached to the circuit board, thereby ensuring the flatness of the protective film when attached, making it difficult for bubbles to appear on the attached protective film, and avoiding affecting the normal use of the circuit board after the film is attached.

[0033] In a preferred embodiment, the protective film is a thermoplastic PI film, and the Tg of the protective film is greater than 225°C.

[0034] In a preferred embodiment, the material of the protective film is thermoplastic polyimide, and the Tg value of the protective film is 233° C. The protective film is a DuPont HT series protective film.

[0035] In a preferred embodiment, the number of the fixed points 2 is an even number, so that any of the fixed points 2 has corresponding symmetrical points on the four edges of the FPC circuit board to be laminated. The process edges include a first process edge 31, a second process edge 32, a third process edge 33 and a fourth process edge 34, the first process edge 31, the second process edge 32, the third process edge 33 and the fourth process edge 34 are respectively located on the four edges of the copper clad board 1, the first process edge 31 is symmetrical with the third process edge 33, the second process edge 32 is symmetrical with the fourth process edge 34, and the fixed points 2 are all located on the first process edge 31 and the third process edge 33; or, the fixed points 2 are all located on the second process edge 32 and the fourth process edge 34. The fixed points 2 are symmetrically arranged, and the combination stability of the fixed points is good, which can avoid the offset problem caused by the misalignment of the protective film such as wrinkles and bends during the process of laminating the protective film, thereby ensuring the accuracy of lamination between the protective film and the circuit board.

[0036] In a preferred embodiment, the number of the fixing points 2 is 6 or 8.

[0037] In a preferred embodiment, the thermal bonding device is an electric soldering iron.

[0038] In a preferred embodiment, the operating temperature of the electric soldering iron is 320-360°C.

[0039] In a preferred embodiment, the operating temperature of the electric soldering iron is 350° C., and the residence time of the electric soldering iron on the protective film is 2-4 seconds.

[0040] In a preferred embodiment, the copper clad laminate 1 is a double-sided copper clad laminate 1 .

[0041] In a preferred embodiment, the copper clad board 1 includes an insulating layer, a first copper clad layer is provided on the first surface of the insulating layer, a second copper clad layer is provided on the second surface of the insulating layer, and the copper layer opening is located on the first copper clad layer; or, the copper layer opening is located on the second copper clad layer.

[0042] The method of the present invention improves the lamination of DuPont HT series protective films on circuit board products, so that this series of protective films can be firmly connected and positioned with existing copper clad boards, achieving no glue pollution and no mechanical damage, and avoiding the adverse effects of existing film laminating processes on product quality. The Tg value of DuPont HT series protective films can reach 233°C, which is the protective film with the highest Tg value in the industry. This protective film is used on high-end products that require high temperature resistance and has superior performance. By laminating this series of protective films on circuit board products, high-temperature resistant circuit board products that meet the requirements can be prepared, and the adverse effects of existing film laminating processes on product quality can be avoided. The present invention achieves effective bonding and fixing of high-temperature resistant high-Tg protective films and FPCs, thereby avoiding the problems of low yield, damage to preparation equipment, inaccurate laminating and positioning of protective films, etc. caused by the use of existing film laminating methods, and obtains high-quality high-temperature resistant FPC circuit boards;

[0043] The flexible circuit board described in the present invention is a double-sided copper-clad board 1, including an insulating layer and a first copper-clad layer located on the first surface of the insulating layer and a second copper-clad layer located on the second surface of the insulating layer. The insulating layer is an insulating material film, also called a protective film, used to protect copper foil.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0045] In the description of this specification, the description with reference to the terms "preferred embodiment", "further embodiment", "other embodiments" or "specific example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0046] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for positioning a protective film for a high temperature resistant circuit board, characterized in that: The steps include: S1. Prepare a copper-clad laminate with process edges on all four sides and a cut protective film; S2, selecting a fixed point on the process edge of the copper clad laminate, removing the copper layer at the position of the fixed point, so that the insulating layer is exposed through the copper layer window at the position of the fixed point, and the exposed insulating layer area at the position of the fixed point is the substrate bonding area; S3, superimposing the protective film on the copper-clad laminate, so that the protective film at the fixed point is in direct contact with the substrate bonding area, and using a thermal bonding device to perform thermal compression bonding between the protective film at the fixed point and the substrate bonding area, so that the protective film is aligned and fixed through the fixed point; S4, using a thermal bonding device to thermally press the protective film and the FPC circuit board to be bonded, to obtain the bonded FPC circuit board.

2. The film positioning method according to claim 1, characterized in that: The protective film is a thermoplastic PI film, and the Tg of the protective film is greater than 225°C.

3. The film positioning method according to claim 2, characterized in that: The material of the protective film is thermoplastic polyimide, and the Tg value of the protective film is 233°C.

4. The film positioning method according to claim 1, characterized in that: The number of the fixed points is an even number, so that any of the fixed points has corresponding symmetrical points on the four edges of the FPC circuit board to be laminated. The process edges include the first process edge, the second process edge, the third process edge and the fourth process edge, the first process edge, the second process edge, the third process edge and the fourth process edge are respectively located on the four edges of the copper clad board, the first process edge is symmetrical with the third process edge, the second process edge is symmetrical with the fourth process edge, and the fixed points are all located on the first process edge and the third process edge; or, the fixed points are all located on the second process edge and the fourth process edge.

5. The film positioning method according to claim 4, characterized in that: The number of the fixing points is 6 or 8.

6. The film positioning method according to claim 1, characterized in that: The thermal bonding equipment is an electric soldering iron.

7. The film positioning method according to claim 6, characterized in that: The operating temperature of the electric soldering iron is 320-360°C.

8. The film positioning method according to claim 7, characterized in that: The operating temperature of the electric soldering iron is 350° C., and the residence time of the electric soldering iron on the protective film is 2-4 seconds.

9. The film positioning method according to claim 1, characterized in that: The copper clad laminate is a double-sided copper clad laminate.

10. The film positioning method according to claim 9, characterized in that: The copper clad board includes an insulating layer, a first copper clad layer is provided on the first surface of the insulating layer, a second copper clad layer is provided on the second surface of the insulating layer, and the copper layer window is located on the first copper clad layer; or, the copper layer window is located on the second copper clad layer.

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