Structure for preventing liquid medicine from entering surface treatment circuit of FPC thick copper product

Abstract

The utility model provides a structure for solving the problem that liquid medicine enters a surface treatment circuit of an FPC (Flexible Printed Circuit) thick copper product. The structure comprises an ultrathin covering film bottom layer, an ultra-thick copper plate circuit layer, an ink layer and an ultrathin covering film layer which are stacked in sequence, the ultra-thin covering film layer is provided with a window, and the ink layer is filled in the ultra-thick copper plate circuit layer at the position of the window. According to the utility model, the structural design that the ink layer is arranged on the ultra-thick copper plate circuit layer is adopted, so that water is prevented from entering or hiding at the windowing position of the ultra-thin covering film layer, and the risk of bonding pad oxidation or electrical property short circuit is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of FPC (flexible printed circuit board), in particular to a structure for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products. Background Art

[0002] With the increasing demand for portable electronic devices, wireless charging has become a must-have feature in new mobile phone manufacturers. Wireless charging technology used in mobile phones all relies on low-power electromagnetic induction. Current flowing through the transmitting end (i.e., the charging base) generates a magnetic field, and the receiving end converts this magnetic field into current through electromagnetic induction. However, the problem arises: the magnetic field strength decreases with distance from the source. Therefore, increasing the distance significantly reduces the magnetic field and the charging rate. Therefore, to shorten the distance between the transmitting and receiving ends, wireless charging coils typically use an ultra-thin black cover film. This film is typically 7.5um thick with PI and 5um adhesive, and is laminated onto the coil, which has a copper thickness of approximately 55 to 90um. Both theoretical and practical results show that the cover film's openings can fill in gaps in the actual circuits. This makes it easy for water to enter or retain water through these openings during post-processing surface treatment, leading to oxidation of the solder pads or the risk of electrical short circuits. Utility Model Content

[0003] The utility model provides a structure for solving the problem of water ingress into the surface treatment circuit of FPC thick copper products, and aims to solve the technical problems in the background technology of easy water ingress or poor water storage from the window position of the covering film.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a structure for solving the problem of liquid injection into the surface treatment circuit of FPC thick copper products, comprising an ultra-thin covering film bottom layer, an ultra-thick copper plate circuit layer, an ink layer and an ultra-thin covering film layer stacked in sequence;

[0005] The ultra-thin covering film layer is provided with a window, and at the window position, the ink layer is filled in the ultra-thick copper plate circuit layer.

[0006] Preferably, the ultra-thin covering film layer and the ultra-thin covering film bottom layer are both 7.5um thick polyimide films with 5um thick glue.

[0007] Preferably, the ultra-thick copper plate circuit layer includes a thick copper substrate and a copper plating layer, and the copper plating layer is provided on the thick copper substrate.

[0008] Preferably, the thickness of the ultra-thick copper plate circuit layer is 55-90um, the thickness of the thick copper substrate is 45um-50um, the thickness of the ink layer is 20um, and the width between the ultra-thin covering film layer and the ink layer is more than 0.3mm.

[0009] Preferably, the copper plating layer is two layers, and the two copper plating layers are respectively arranged on both sides of the copper thick substrate.

[0010] Preferably, it further comprises a reinforcement layer, wherein the reinforcement layer is connected to the bottom layer of the ultra-thin covering film.

[0011] Preferably, it further comprises a bottom ink layer, and the bottom layer of the ultra-thin cover film is provided with a window, and at the window position, the bottom ink layer is filled in the ultra-thick copper plate circuit layer.

[0012] Preferably, the ultra-thick copper plate circuit layer is provided with a through hole, and the ink layer is filled in the ultra-thick copper plate circuit layer at the position of the through hole.

[0013] Preferably, a longitudinal ink layer is provided at the through hole position, and the longitudinal ink layer is provided on the through hole wall and passes through the ultra-thin covering film bottom layer, the ultra-thick copper plate circuit layer and the ultra-thin covering film layer.

[0014] Preferably, an ink layer is further provided on the ultra-thin covering film layer.

[0015] The utility model provides a structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products, which has the following beneficial effects:

[0016] The structural design of setting the ink layer on the ultra-thick copper plate circuit layer is adopted. The window position is first filled with solder mask ink, and then the ultra-thin covering film is pressed. This can solve the problem of water inflow or water storage between the circuits, avoid water inflow or water storage at the window position of the ultra-thin covering film layer, reduce the risk of pad oxidation or electrical short circuit, and prevent poor performance from flowing out. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a preferred embodiment of the utility model for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products;

[0018] Figure 2 This is a structural diagram of another preferred embodiment of the utility model for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products;

[0019] Figure 3 This is a structural diagram of another preferred embodiment of the utility model for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products;

[0020] Figure 4 This is a structural diagram of another preferred embodiment of the utility model for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products;

[0021] In the picture:

[0022] 1. Reinforcement layer; 2. Ultra-thin cover film bottom layer; 3. Ultra-thick copper circuit layer; 4. Ink layer; 5. Ultra-thin cover film layer; 31. Thick copper substrate; 32. Copper plating layer; 41. Bottom ink layer; 40. Vertical ink layer. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0024] The utility model aims at solving the existing problems and provides a structure for solving the problem of introducing liquid medicine into the surface treatment circuit of FPC thick copper products.

[0025] In one embodiment, a structure for solving the problem of adding liquid to the surface treatment circuit of FPC thick copper products is provided. Figure 1 As shown, it includes a reinforcing layer 1, an ultra-thin covering film bottom layer 2, an ultra-thick copper plate circuit layer 3, an ink layer 4 and an ultra-thin covering film layer 5 stacked in sequence; the reinforcing layer 1 is connected to the ultra-thin covering film bottom layer 2.

[0026] The ultra-thin covering film layer 5 is provided with a window, and at the window position, the ink layer 4 is filled in the ultra-thick copper plate circuit layer 3.

[0027] The ultra-thin cover film bottom layer 2 may also have a window, and the ink layer 4 may also be filled in the ultra-thick copper circuit layer 3 near the window of the ultra-thin cover film bottom layer 2. However, in this embodiment, the window is a single-sided design, with a window only provided in the ultra-thin cover film layer 5, and the corresponding ink layer 4 is also only provided on one side.

[0028] The ultra-thin covering film layer 5 and the ultra-thin covering film bottom layer 2 are polyimide films.

[0029] The ultra-thin covering film layer 5 and the ultra-thin covering film bottom layer 2 are both made of a polyimide film with a thickness of 7.5 μm and a 5 μm glue.

[0030] The thickness of the ultra-thick copper plate circuit layer 3 is 55-90 μm.

[0031] The ultra-thick copper plate circuit layer 3 includes a thick copper substrate 31 and a copper plating layer 32. The thick copper substrate 31 has a thickness of 45 μm to 50 μm. The copper plating layer 32 is provided on the thick copper substrate 31.

[0032] The copper plating layer 32 is composed of two layers, and the two layers of the copper plating layer 32 are respectively disposed on both sides of the copper thick substrate 31 .

[0033] The ink layer 4 has a thickness of 20 μm.

[0034] The ultra-thin cover film layer 5 and the ink layer 4 must be bonded to a width of at least 0.3mm. This connection must be at least 0.3mm to prevent a flawed bond and ensure that the finished product is not oxidized by post-process surface treatment after exposure and development.

[0035] In another preferred embodiment, Figure 2 As shown, it also includes a bottom ink layer 41. The bottom layer 2 of the ultra-thin cover film is provided with a window. At the window position, the bottom ink layer 41 is filled in the ultra-thick copper plate circuit layer 3.

[0036] As a further improvement of this embodiment, Figure 3 As shown, the ultra-thick copper plate circuit layer 3 is provided with a through hole, and the ink layer 4 is filled in the ultra-thick copper plate circuit layer 3 at the through hole position. The through hole is also treated with the ink layer 4 to prevent water from entering or poor water storage.

[0037] A longitudinal ink layer 40 is provided at the through hole position. The longitudinal ink layer 40 is provided on the through hole wall and passes through the ultra-thin cover film bottom layer 2 , the ultra-thick copper plate circuit layer 3 and the ultra-thin cover film layer 5 .

[0038] In this embodiment, the longitudinal ink layer design prevents water from entering or retaining water at the points where the ultra-thick copper circuit layer 3 contacts the through-holes. The through-hole walls can have a metal wall structure, which can be used to electrically connect to the thick copper substrate 31 and design circuits at the through-holes. Alternatively, the metal wall can be omitted, allowing the design to function as a drilled hole in the thick copper substrate 31.

[0039] As a further improvement of this embodiment, Figure 4 As shown, an ink layer is also provided on the ultra-thin covering film layer 5 .

[0040] The utility model provides a structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products, which has the following beneficial effects:

[0041] The structural design of providing the ink layer 4 within the ultra-thick copper plate circuit layer 3, first filling the window locations with solder mask ink before laminating the ultra-thin cover film, can solve the problem of water ingress or water storage between the circuits, prevent water ingress or water storage at the window locations of the ultra-thin cover film layer 5, reduce the risk of pad oxidation or electrical short circuits, and prevent the leakage of poor performance. This improved solution is easy to manufacture and can effectively solve the problem of liquid ingress caused by the poor combination of ultra-thick copper plate and ultra-thin protective film, improve the oxidation and micro-shorting of the window pads, and prevent the leakage of poor performance.

[0042] The corresponding circuits are made on the ultra-thick copper plate circuit layer 3 with an ultra-thick copper thickness of about 55 to 90 μm. The circuit spacing is generally about 50 to 100 μm. The ink layer 4 is then filled between the circuits. After the ink is printed, it is exposed and developed to flow out the required pads. It is then combined with the ultra-thin protective film layer 5. The combination is connected by more than 0.3 mm to prevent loose bonding, so as to achieve the effect of the finished product. It can be confirmed that the pads are not oxidized by the post-process surface treatment.

[0043] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles described in the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products, characterized in that: It comprises an ultra-thin covering film bottom layer (2), an ultra-thick copper plate circuit layer (3), an ink layer (4) and an ultra-thin covering film layer (5) which are stacked in sequence; The ultra-thin covering film layer (5) is provided with a window, and at the window position, the ink layer (4) is filled in the ultra-thick copper plate circuit layer (3).

2. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: The ultra-thin covering film layer (5) and the ultra-thin covering film bottom layer (2) are both polyimide films with a thickness of 7.5 μm, and a 5 μm glue thickness.

3. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: The ultra-thick copper plate circuit layer (3) comprises a thick copper substrate (31) and a copper plating layer (32), wherein the copper plating layer (32) is arranged on the thick copper substrate (31).

4. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: The thickness of the ultra-thick copper plate circuit layer (3) is 55-90 μm, the thickness of the thick copper substrate (31) is 45-50 μm, the thickness of the ink layer (4) is 20 μm, and the width between the ultra-thin covering film layer (5) and the ink layer (4) is greater than 0.3 mm.

5. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 3 is characterized in that: The copper plating layer (32) is composed of two layers, and the two layers of the copper plating layer (32) are respectively arranged on both sides of the copper thick substrate (31).

6. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: It also includes a reinforcement layer (1), which is connected to the bottom layer (2) of the ultra-thin covering film.

7. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: It also includes a bottom ink layer, and the bottom layer (2) of the ultra-thin covering film is provided with a window. At the window position, the bottom ink layer is filled in the ultra-thick copper plate circuit layer (3).

8. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: The ultra-thick copper plate circuit layer (3) is provided with a through hole, and the ink layer (4) is filled in the ultra-thick copper plate circuit layer (3) at the position of the through hole.

9. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 8 is characterized in that: A longitudinal ink layer (40) is provided at the through hole position. The longitudinal ink layer (40) is provided on the through hole wall and passes through the ultra-thin covering film bottom layer (2), the ultra-thick copper plate circuit layer (3) and the ultra-thin covering film layer (5).

10. The structure for solving the problem of adding liquid medicine to the surface treatment circuit of FPC thick copper products according to claim 1 is characterized in that: An ink layer is also provided on the ultra-thin covering film layer (5).

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