Circuit and fuse processing technology of flexible circuit board

Abstract

The invention discloses a circuit and fuse processing technology of a flexible circuit board. The circuit and fuse processing technology comprises the steps that a release film is pressed and attached to the bottom of a PET silica gel film through an upper rubber roller and a lower steel roller; cutting off the release film at the alignment position of the circuit and the fuse at the bottom of the PET silica gel film through a lower circular knife mold according to the positions of the circuit and the fuse needing to be reserved on the metal foil, and reserving the release film outside the alignment position of the circuit and the fuse; aligning the position, where the release film is cut off, of the PET silica gel film according to the position, where the circuit and the fuse need to be reserved, on the metal foil, pressing and attaching the metal foil to the PET silica gel film with the release film face through an upper rubber roller and a lower steel roller, and cutting out the circuit and the fuse through a lower circular knife mold; a PET silica gel film is attached to the bottom of the metal foil with the cut circuit and the cut fuse, the PET silica gel film and metal foil waste at the bottom of the metal foil are removed, and the cut circuit and the cut fuse are reserved on the PET silica gel film with the release film face.

Description

Technical Field

[0001] The invention relates to the field of flexible circuit board processing, in particular to a circuit and fuse processing technology of a flexible circuit board. Background Art

[0002] With the development of modern society, based on the popularization of charging piles that can be seen everywhere, the shipment growth of new energy vehicles has shown a blowout growth, which not only boosts domestic demand but also increases foreign exchange earnings. Due to the battery life problem, a flexible printed circuit board (FPC) is used to replace most of the wiring harnesses to increase battery capacity and thus improve battery life. The current circuits and fuses of the flexible circuit board are mainly made by directly bonding the metal foil 2 to the bottom of the PET silicone film 1, cutting the circuits and fuses 4 with a mold, and then bonding the PET silicone film 3 to the bottom of the metal foil, removing the PET silicone film and metal foil waste at the bottom of the metal foil, so that the cut circuits and fuses are retained on the PET silicone film on the metal foil. Figure 1 As shown, however, since the bottom of the metal foil is directly attached to the PET silicone film, the retained circuits and fuses are in the same plane as the metal foil waste. When the PET silicone film and the metal foil waste at the bottom of the metal foil are removed, the circuits and fuses are relatively small and soft, and are easily pulled up or down by the removal force, causing the small and soft circuits and fuses to be misaligned and deformed on the metal foil, thereby affecting the yield rate of the flexible circuit board product. Even if the waste is peeled off slowly, it is difficult to improve the yield rate, and it will cause a decrease in production efficiency.

[0003] Especially when fuses are made of metal foil, in order to ensure that the fuse can disconnect the circuit when a large current passes through, the thickness and line width of the fuse must be made smaller. However, fuses with smaller thickness and line width are more prone to misalignment and deformation when the upward or downward pull of the removal force is removed. Summary of the invention

[0004] The object of the present invention is to provide a circuit and fuse processing technology for a flexible circuit board that can avoid misalignment and deformation of the circuit and the fuse on a metal foil material, so as to improve the yield rate of the flexible circuit board product.

[0005] The circuit and fuse processing technology of the flexible circuit board of the present invention comprises the following steps: S1. Press the release film with an original film thickness of 0.02-0.08 mm, a release adhesive thickness of 0.001-0.005 mm, and a peeling force of 1-10 G onto the bottom of a PET silicone film with an original film thickness of 0.06-0.08 mm, a glue thickness of 0.01-0.03 mm, and a peeling force of 600-1000 G through an upper glue roller and a lower steel roller; S2. According to the positions of the circuit and the fuse that need to be retained on the metal foil with a thickness of 0.03-0.12 mm, the release film at the position where the circuit and the fuse are aligned is cut off at the bottom of the PET silicone film by a lower circular knife mold. The width of the cut release film is 0.1-0.2 mm wider than the width of the circuit and the fuse, and the release film outside the position where the circuit and the fuse are aligned is retained; S3, aligning the position where the release film of the PET silicone film has been cut off according to the position where the circuit and the fuse need to be retained on the metal foil, and pressing the metal foil tightly onto the PET silicone film with the release film surface by the upper rubber roller and the lower steel roller, and cutting out the circuit and the fuse curve by the lower circular knife mold; S4. Attach a PET silicone film to the bottom of the metal foil with the circuits and fuses cut, remove the PET silicone film and metal foil waste at the bottom of the metal foil, and keep the cut circuits and fuses on the PET silicone film with the release film surface.

[0006] The fuse is a beaded fuse and / or a curved fuse. The beaded fuse is composed of beaded metal foils connected in series, and the line width of each beaded metal foil connection line is 0.12-0.18mm; the line width of the curved fuse is 0.12-0.18mm.

[0007] However, the fuse is not limited to the above two types, and other fuses requiring a line width of 0.12-0.18 mm are within the protection scope of the present invention.

[0008] In the above process, the original film thickness, glue thickness, and peeling force of the PET silicone film, the original film thickness and release glue thickness of the release film, and the width of the removed release film will significantly affect the yield rate.

[0009] The original film of PET silicone film mainly needs to play a supporting role. If the thickness is too thin, it will cause insufficient support.

[0010] The glue of PET silicone film not only plays a bonding role but also a buffering role in the process of cutting release film and metal circuit. If the glue is too thin, it is easy to damage the original film during the circuit cutting process. If the glue is too thick, it is easy to cause the metal foil to move slightly in the vertical direction during the cutting process, which may cause a decrease in the yield rate.

[0011] The appropriate glue peeling force of the PET silicone film will also affect the release film and metal foil to prevent sliding during the cutting process, and will not be dislocated, deformed, or even torn when peeling the conductive circuit and fuse.

[0012] The thickness of the release film is mainly related to the thickness of the metal foil. The sum of the original film thickness of the release film and the thickness of the release adhesive needs to be less than the thickness of the metal foil, so that the metal foil can be recessed into the film after rolling, and bonded to the PET high-viscosity silicone film, and form a staggered structure after cutting the circuit, so that no damage will be caused during the process of stripping the waste.

[0013] In step S2, the width of the cut release film is 0.1-0.2mm wider than the width of the circuit and the fuse, so that the preset circuit and fuse parts of the metal foil can be attached to the PET silicone film, and then the circuit and the fuse are cut, which can ensure that the metal foil will not be dislocated, deformed, or even damaged during the cutting process.

[0014] As a preferred embodiment of the present invention, in S1, the original film thickness of the PET silicone film is 0.065-0.075 mm, the glue thickness is 0.02-0.025 mm, and the peeling force is 700-800 G.

[0015] As a preferred embodiment of the present invention, the thickness of the release film (the sum of the original film thickness and the release adhesive thickness) is 0.6-0.8 times the thickness of the metal foil.

[0016] As a preferred solution of the present invention, the release film is a single-sided adhesive release film, and the side with the single-sided adhesive faces downward and contacts the metal foil.

[0017] As a preferred embodiment of the present invention, the circuit and fuse processing process of the flexible circuit board also includes flattening and shaping the circuit and fuse retained on the PET silicone film with the release film surface on the metal foil material by upper and lower steel rods.

[0018] As a preferred embodiment of the present invention, the method further comprises heating and bonding the thermosetting adhesive film to the PET silicone film through an upper adhesive roller, a lower steel roller, and upper and lower heating rollers, wherein the PET silicone film is located at the bottom of the thermosetting adhesive film, wherein the heating temperature range of the heating roller is 100-140°C; On the flattened and shaped metal foil, the thermosetting adhesive film is heated and bonded to the metal foil with circuits and fuses through the upper adhesive roller, the lower steel roller, and the upper and lower heating rollers. The thermosetting adhesive film is located at the bottom of the PET silicone film with the release film surface; Remove the PET silicone film with the release film together with the release film; Then remove the PET silicone film and the metal foil with circuits and fuses on the release film surface, cut the pad windows, and heat and press the thermosetting adhesive film with upper and lower heating rollers; Remove the PET silicone film and the pad waste at the bottom of the thermosetting adhesive film.

[0019] As a preferred solution of the present invention, the thermosetting adhesive film is a polyimide thermosetting adhesive film or a PET thermosetting adhesive film, and the thickness of the thermosetting adhesive film is 0.05 to 0.15 mm.

[0020] The metal foil material suitable for the process of the present invention is one or more combinations of copper foil (i.e. pure copper foil), aluminum foil, constantan foil, iron-chromium-aluminum alloy foil, stainless steel foil, brass foil, gold foil, nickel foil, iron foil, white copper foil, silver foil, manganese copper foil, nickel-chromium alloy foil, and aluminum-nickel-iron alloy foil.

[0021] As a preferred solution of the present invention, the glue of the PET silicone film contains a high viscosity agent.

[0022] The circuit and fuse processing technology of the flexible circuit board described in the present invention mainly selects a PET silicone film with specific parameters / a release film with specific parameters, first cuts the preset circuit circuit and fuse circuit at the corresponding part of the release film to form an inwardly concave "route and fuse line reserved position", and then presses the metal foil material to one side of the release film, the metal foil material circuit part will be recessed in the "route and fuse line reserved position" and bonded to the PET high-viscosity silicone film, and then cuts the part where the metal copper foil is bonded to the PET high-viscosity silicone film to obtain a regular conductive circuit and fuse, after which the conductive circuit and fuse will all fall into the "route and fuse line reserved position", and the thickness of the conductive circuit and fuse is higher than the thickness of the release film, forming a sufficient interlayer spacing, even if the speed of peeling off the release film and the metal foil waste is fast, it is not easy to cause the conductive circuit and fuse to be misaligned and deformed. Therefore, the process of the present invention has the advantages of high yield and high efficiency, and is particularly suitable for the preparation of fuses with complex structures and small thickness / width. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the circuit and fuse processing of the prior art flexible circuit board in the background technology; Figure 2 It is a schematic diagram of the process flow of processing the circuit and fuse of the flexible circuit board of the present invention; Figure 3 It is a schematic diagram of the release film being attached to the bottom of the PET silicone film; Figure 4 It is a schematic diagram of release film cutting; Figure 5 It is a schematic diagram after the release film is cut off; Figure 6 A schematic diagram of pressing a metal foil tightly against a PET silicone film with a release film surface; Figure 7 Schematic diagram of cutting line and fuse; Figure 8 is a schematic diagram of a fuse; Fig. 9 This is a schematic diagram of attaching a PET silicone film to the bottom of the metal foil material with the circuits and fuses cut; Fig.10 Schematic diagram of retaining the cut circuits and fuses on the PET silicone film with release film surface; Fig.11 Schematic diagram for leveling the circuits and fuses on the metal foil; Fig.12 A schematic diagram of heating and bonding the thermosetting adhesive film 17 to the metal foil with circuits and fuses; Fig.13 Schematic diagram of removing the PET silicone film and pad waste located at the bottom of the thermosetting adhesive film. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] A circuit and fuse processing technology for a flexible circuit board, such as Figure 2 As shown, the following steps: S1, through the upper glue roller 5 and the lower steel roller 6, the release film 7 with an original film thickness of 0.02-0.08mm, a release glue thickness of 0.001-0.005mm, and a peeling force of 1-10G is pressed and attached to the bottom of the PET silicone film 8 with an original film thickness of 0.06-0.08mm, a glue thickness of 0.01-0.03mm, and a peeling force of 600-1000G, as shown in FIG. Figure 3 shown.

[0026] The PET silicone film uses a PET silicone film with high viscosity. The PET silicone film with high viscosity can be bonded to the release film, and then bonded to the metal foil, which has a more stable effect. In addition, the original film thickness of the PET silicone film is 0.065-0.075mm, the glue thickness is 0.02-0.025mm, and the peeling force is 700-800G. The original film is bonded to the release film better, and provides a more stable support for the width of the cut release film, which is very important for improving the yield of the entire process. In addition, the release film is a single-sided adhesive release film, with the side with the single-sided adhesive facing down and in contact with the metal foil, and the non-adhesive side of the release film is pasted with the PET silicone film, so that the release film can be better and completely removed after subsequent hot pressing.

[0027] S2. According to the position of the circuit and the fuse that needs to be retained on the metal foil with a thickness of 0.03-0.12 mm, the release film at the position where the circuit and the fuse are aligned is cut off by the lower circular knife mold 9 at the bottom of the PET silicone film. The width of the cut release film 10 is 0.1-0.2 mm wider than the width of the circuit and the fuse. The release film outside the position where the circuit and the fuse are aligned is retained, such as Figure 4 and Figure 5 shown.

[0028] When the release film is cut, the width of the cut position is 0.1-0.2mm wider than the width of the circuit and the fuse, so that the circuit and the fuse on the metal foil can be better embedded in the concave "route and fuse line reserved position", which is more convenient to operate; in addition, through experiments, it can be known that when the thickness of the release film is 0.6-0.8 times the thickness of the metal foil, the peeling release adhesive and metal foil waste are not likely to touch the circuit and the fuse, thereby improving the yield rate.

[0029] S3, align the position where the release film of the PET silicone film has been cut off according to the position 12 on the metal foil material 11 where the circuit and the fuse need to be retained, and press the metal foil material tightly onto the PET silicone film with the release film surface by the upper rubber roller and the lower steel roller. Figure 6 As shown, the circuit and fuse are cut out by the lower circular knife mold 9 as shown Figure 7 As shown, the fuse includes a beaded fuse 14 and a curved fuse 15 as shown in FIG. Figure 8 As shown, the beaded fuse is connected in series by beaded metal foils, and the line width of each beaded metal foil connection line is 0.12-0.18mm; the line width of the curved bent fuse is 0.12-0.18mm.

[0030] In addition, by including but not limited to two shapes of fuses, bead-shaped fuses and curved fuses, the line width of each bead-shaped copper foil connecting line is 0.12-0.18mm; the line width of the curved fuse is 0.12-0.18mm, so that when a short circuit or excessive current occurs, the fuse can be blown in a short time, thereby achieving the purpose of protecting other circuits.

[0031] The metal foil is polished on both sides, and the surface dyne value is ≥36, so that the surface adhesion of the metal foil is stronger, so that the release film can better bond the metal foil together.

[0032] S4, stick the PET silicone film 16 on the bottom of the metal foil material with the circuit and fuse cut. Fig. 9 As shown, the PET silicone film and the metal foil waste at the bottom of the metal foil are removed, so that the cut circuit and the fuse 13 are retained on the PET silicone film with the release film surface. Fig.10 shown.

[0033] The metal foils suitable for the process of the present invention are copper foil, aluminum foil, constantan foil, iron-chromium-aluminum alloy foil, stainless steel foil, brass foil, gold foil, nickel foil, iron foil, white copper foil, silver foil, manganese copper foil, nickel-chromium alloy foil, aluminum-nickel-iron alloy foil, etc. It can also be a combination of multiple foils, depending on the materials required for the circuit and the fuse.

[0034] Then the circuits and fuses retained on the PET silicone film with the release film surface are flattened / shaped on the metal foil by upper and lower steel rods, so that the circuits and fuses on the metal foil are smoother. Fig.11 As shown, it provides convenience for subsequent processing steps.

[0035] The thermosetting adhesive film is heated and bonded to the PET silicone film by the upper glue roller, the lower steel roller, and the upper and lower heating rollers. The PET silicone film is located at the bottom of the thermosetting adhesive film. The thermosetting adhesive film 17 is heated and bonded to the metal foil with circuits and fuses by the upper glue roller, the lower steel roller, and the upper and lower heating rollers 18 on the flattened and shaped metal foil. The thermosetting adhesive film is located at the bottom of the PET silicone film with the release film surface. Fig.12 As shown; the PET silicone film with the release film surface is removed together with the release film; on the metal foil with circuits and fuses on which the PET silicone film and the release film surface are removed, the pad window is cut, and the thermosetting adhesive film is pressed by heating and pressing the upper and lower heating rollers; the PET silicone film at the bottom of the thermosetting adhesive film and the pad waste are removed together as shown Fig.13 As shown, the circuit and the fuse can be covered and protected, which facilitates the subsequent making of the metal foil into a flexible circuit board. The PET silicone film located at the bottom of the thermosetting adhesive film also adopts a PET silicone film with high viscosity. The thickness of the PET silicone film is 0.06mm and the peeling force is 10-80G. Among them, the thermosetting adhesive film is a polyimide thermosetting adhesive film or a PET thermosetting adhesive film with a thickness of 0.05 to 0.15mm. An acrylic adhesive film with a thickness of 0.05mm and a peeling force of 1-20G can be selected as a better one, so as to prevent deformation when the through-hole of the product is peeled off. Furthermore, the present invention adjusts the parameters in the processing technology of the circuit and fuse of the above-mentioned flexible circuit board, prepares the product, and conducts various tests as follows: Yield rate: Use the process of the embodiment and comparative example to repeatedly manufacture the following 1000 circuits, observe and record whether the circuits and fuses are displaced and / or deformed, and observe the deviations between the circuits and fuses and the design, and calculate the yield rate.

[0036] The key parameters and test results of the process of Example (A) and Comparative Example (B) are shown in the following table:

[0037] Continuation table:

[0038] Continuation table:

[0039] Continuation table:

[0040] It can be seen from the above test results that the products produced by the circuit and fuse processing technology of the flexible circuit board of the present invention have the advantages of high yield and high efficiency, and are particularly suitable for the preparation of fuses with complex structures and small thickness / width.

[0041] Specifically, it can be seen from A5 / A7-A9 that the preferred parameters of the PET silicone film have a higher yield rate.

[0042] From A3-A6, it can be seen that the yield rate is higher when the thickness of the release film is 0.6-0.8 times the thickness of the metal foil.

[0043] From B1 / B2, it can be seen that when the thickness of the release film is ≥ the thickness of the metal foil, the staggered structure cannot be achieved. When cutting the circuit and stripping the waste, the circuit and fuse structure will be damaged, resulting in a decrease in the yield rate.

[0044] From B3, we can see that when the release adhesive thickness is too high, the peeling force is too high. As can be seen from B4, if the peeling force of the PET silicone film is too low, the metal foil will slide during the cutting process, causing the circuit cutting to be misaligned.

[0045] From B5, we can see that if the peeling force of the PET silicone film is too high, the yield rate will also be reduced.

[0046] It can be seen from B6 / B7 that if the difference between the width of the cut release film and the width of the corresponding circuit and fuse is not within the scope of the present invention, the circuit and fuse will fail to meet the standards when they are cut.

[0047] From B8, we can see that if the original film thickness of the PET silicone film is too low, the support is insufficient and the product yield is low.

[0048] From B9, we can see that if the glue thickness of the PET silicone film is too thick, the circuit will be slightly displaced during the circuit cutting process, resulting in a decrease in the yield rate.

[0049] From B10, it can be seen that if the glue thickness of the PET silicone film is too low, the original film of the PET silicone film is easily damaged during the circuit cutting process, resulting in a decrease in strength and a reduction in the yield rate.

[0050] The above embodiments are only used to illustrate the detailed scheme of the present invention, and the present invention is not limited to the above detailed scheme, that is, it does not mean that the present invention must rely on the above detailed scheme to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A process for processing circuits and fuses of a flexible circuit board, characterized in that: The following steps are involved: S1. Press the release film with an original film thickness of 0.02-0.08 mm, a release adhesive thickness of 0.001-0.005 mm, and a peeling force of 1-10 G onto the bottom of a PET silicone film with an original film thickness of 0.06-0.08 mm, a glue thickness of 0.01-0.03 mm, and a peeling force of 600-1000 G through an upper glue roller and a lower steel roller; S2. According to the positions of the circuit and the fuse that need to be retained on the metal foil with a thickness of 0.03-0.12 mm, the release film at the position where the circuit and the fuse are aligned is cut off at the bottom of the PET silicone film by a lower circular knife mold. The width of the cut release film is 0.1-0.2 mm wider than the width of the circuit and the fuse, and the release film outside the position where the circuit and the fuse are aligned is retained; S3, aligning the position where the release film of the PET silicone film has been cut off according to the position where the circuit and the fuse need to be retained on the metal foil, and pressing the metal foil tightly onto the PET silicone film with the release film surface by the upper rubber roller and the lower steel roller, and cutting out the circuit and the fuse by the lower circular knife mold; S4. Attach a PET silicone film to the bottom of the metal foil with the circuits and fuses cut, remove the PET silicone film and metal foil waste at the bottom of the metal foil, and keep the cut circuits and fuses on the PET silicone film with the release film surface.

2. The flexible circuit board processing technology according to claim 1, characterized in that: The fuse is a beaded fuse and / or a curved fuse. The beaded fuse is composed of beaded metal foils connected in series, and the line width of each beaded metal foil connection line is 0.12-0.18mm; the line width of the curved fuse is 0.12-0.18mm.

3. The flexible circuit board processing technology according to claim 1, characterized in that: In S1, the original film thickness of the PET silicone film is 0.065-0.075mm, the glue thickness is 0.02-0.025mm, and the peeling force is 700-800G.

4. The flexible circuit board processing technology according to claim 1, characterized in that: The thickness of the release film is 0.6-0.8 times the thickness of the metal foil.

5. The flexible circuit board processing technology according to any one of claims 1 to 3, characterized in that: The release film is a single-sided adhesive release film, and the side with the single-sided adhesive faces downward and contacts the metal foil.

6. The flexible circuit board processing technology according to any one of claims 1 to 3, characterized in that: The processing technology of the circuit and fuse of the flexible circuit board also includes flattening / shaping the circuit and fuse retained on the PET silicone film with the release film surface by upper and lower steel rods on the metal foil material.

7. The flexible circuit board processing technology according to claim 6, characterized in that: The process also includes heating and bonding the thermosetting adhesive film to the PET silicone film through an upper adhesive roller, a lower steel roller, and upper and lower heating rollers, wherein the PET silicone film is located at the bottom of the thermosetting adhesive film; On the flattened and shaped metal foil, the thermosetting adhesive film is heated and bonded to the metal foil with circuits and fuses through the upper adhesive roller, the lower steel roller, and the upper and lower heating rollers. The thermosetting adhesive film is located at the bottom of the PET silicone film with the release film surface; Remove the PET silicone film with the release film together with the release film; Then remove the PET silicone film and the metal foil with circuits and fuses on the release film surface, cut the pad windows, and heat and press the thermosetting adhesive film with upper and lower heating rollers; Remove the PET silicone film and the pad waste at the bottom of the thermosetting adhesive film.

8. The flexible circuit board processing technology according to claim 7, characterized in that: The thermosetting adhesive film is a polyimide thermosetting adhesive film or a PET thermosetting adhesive film, and has a thickness of 0.05-0.15 mm.

9. The flexible circuit board processing technology according to claim 1, characterized in that: The metal foil is a combination of one or more of copper foil, aluminum foil, constantan foil, iron-chromium-aluminum alloy foil, stainless steel foil, brass foil, gold foil, nickel foil, iron foil, white copper foil, silver foil, manganese copper foil, nickel-chromium alloy foil, and aluminum-nickel-iron alloy foil.

10. The flexible circuit board processing technology according to claim 1, characterized in that: The glue of the PET silicone film has high viscosity.

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