Flexible printed circuit board and electronic device
By using OSP layers, electroplated nickel plating, or electroplated gold plating as protective film layers on flexible printed circuit boards, the problem of excessive thickness of flexible printed circuit boards is solved, achieving a balance between thinness and performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2026-03-27
AI Technical Summary
Existing flexible printed circuit boards are relatively thick, making it difficult to meet the requirements of modern electronic devices for thinness and flexibility.
OSP layer, electroplated nickel layer, or electroplated gold layer are used as protective film layers to replace traditional plastic film covering layers, thereby reducing the thickness of flexible printed circuit boards.
It effectively reduces the thickness of flexible printed circuit boards while maintaining their performance, making them suitable for a wider range of applications.
Smart Images
Figure CN224054486U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The embodiment of the present application relates to the technical field of flexible printed circuit board, in particular to a flexible printed circuit board and electronic equipment. BACKGROUND
[0002] The flexible printed circuit board (FPCB) in the field of wireless charging (WPC) is an electronic circuit board taking a flexible substrate as a carrier. Compared with the traditional rigid circuit board, the FPCB has the advantages of being thinner, lighter, smaller and more flexible, and can adapt to more different forms and space designs of electronic products.
[0003] Reducing the thickness of the FPCB has important significance in practical application. For example, reducing the thickness of the flexible printed circuit board not only helps to meet the demand of modern electronic equipment for thin and light FPCB and miniaturization, but also helps to improve the flexibility of the FPCB, so that the FPCB can play a greater role in more extensive application scenarios. CONTENT OF THE UTILITY MODEL
[0004] In order to reduce the thickness of the flexible printed circuit board, the embodiment of the present application provides a flexible printed circuit board and electronic equipment.
[0005] In order to solve the above technical problems, the embodiment of the present application provides the following technical scheme:
[0006] In the first aspect of the present application, a flexible printed circuit board is provided, which comprises a plastic film cover layer, a first copper foil layer, a substrate layer, a second copper foil layer, a protective film layer and a double-sided adhesive layer which are sequentially stacked; wherein the surface of the second copper foil layer close to the protective film layer is a bare copper surface, and the protective film layer is arranged on the bare copper surface, and the protective film layer is an OSP layer, an electroplated nickel plating layer or an electroplated gold plating layer.
[0007] In the embodiment of the present application, the flexible printed circuit board comprises a plastic film cover layer, a first copper foil layer, a substrate layer, a second copper foil layer, a protective film layer and a double-sided adhesive layer which are sequentially stacked; wherein the surface of the second copper foil layer close to the protective film layer is a bare copper surface, and the protective film layer is arranged on the bare copper surface. Since the thickness of the OSP layer, the electroplated nickel plating layer or the electroplated gold plating layer is smaller than the thickness of the plastic film cover layer, compared with using the plastic film cover layer as the protective film layer of the bare copper surface of the second copper foil layer close to the protective film layer, the embodiment of the present application uses the OSP layer, the electroplated nickel plating layer or the electroplated gold plating layer as the protective film layer to reduce the thickness of the flexible printed circuit board.
[0008] In some embodiments, the protective film layer 105 is an OSP layer, and the thickness of the OSP layer is 0.2-0.5 microns.
[0009] In some embodiments, the protective film layer 105 is an electroplated nickel plating layer, and the thickness of the electroplated nickel plating layer is 3 μm to 8 μm.
[0010] In some embodiments, the protective film layer 105 is an electroplated gold plating layer, and the thickness of the electroplated gold plating layer is 1 μm to 3 μm.
[0011] In some embodiments, the thickness of the plastic film cover layer 101 is 12.5 μm to 50 μm.
[0012] In some embodiments, the plastic film cover layer 101 is a polyimide film.
[0013] In some embodiments, the thickness of the first copper foil layer 102 and the second copper foil layer 104 is 45 μm to 65 μm.
[0014] In some embodiments, the substrate layer 103 is a polyimide substrate.
[0015] In some embodiments, the thickness of the substrate layer 103 is 10 μm to 15 μm.
[0016] In a second aspect of the present application, an electronic device is provided, comprising a main body; and the flexible printed circuit board of the first aspect; wherein the flexible printed circuit board is mounted to the main body.
[0017] It should be understood that the content described in the summary section is not intended to limit the key or important features of the present disclosure, nor to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.
[0019] Figure 1 is a structural schematic diagram of a flexible printed circuit board provided by an embodiment of the present application;
[0020] Figure 2 is a structural schematic diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION
[0021] The principles and spirit of the present disclosure will be described below with reference to several exemplary embodiments shown in the accompanying drawings. It should be understood that the description of these specific embodiments is only to enable those skilled in the art to better understand and implement the present disclosure, and is not intended to limit the scope of the present disclosure in any way. In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art.
[0022] As used herein, the term "includes" and its variants are to be read as open-ended terms that mean "includes, but is not limited to." The term "based on" is to be read as "based, at least in part, on." The term "one embodiment" or "an embodiment" means "at least one embodiment." The terms "a first," "a second," etc. do not mean "the first" or "the second," but are used to distinguish a different or like object. Thus, these terms are used interchangeably and are merely to distinguish one different or like object from another different or like object.
[0023] Please refer to Figure 1 In the embodiments of the present application, the flexible printed circuit board 100 comprises a plastic film cover layer 101, a first copper foil layer 102, a substrate layer 103, a second copper foil layer 104, a protective film layer 105 and a double-sided adhesive layer 106 arranged in sequence. The surface of the second copper foil layer 102 close to the side of the protective film layer 105 is a bare copper surface, and the protective film layer 105 is arranged on the bare copper surface. The protective film layer 105 is an OSP layer, an electroplated nickel plating layer or an electroplated gold plating layer.
[0024] In some embodiments, the protective film layer 105 is an organic solder-ability preservatives (OSP) layer. The OSP layer can specifically be a stable complex formed by a benzotriazole or imidazole compound (such as 2-methyl imidazole) and a copper surface. The complex forms a smooth and dense organic cover layer on the copper surface, preventing the oxidation of the bare copper surface and maintaining solderability. The OSP layer has the following advantages: 1) the cover layer is smooth, which is compatible with lead-free solder and no-clean flux; 2) suitable for 2-3 assembly processes; 3) solderability can be maintained for 6 months; 4) the surface treatment layer is smooth, making it easy to mount components. Specifically, in other embodiments, the thickness of the OSP layer can be specifically 0.2 μm-0.5 μm.
[0025] In some embodiments, the protective film layer 105 is an electroplated nickel plating layer, and the thickness of the electroplated nickel plating layer is 3 μm-8 μm. In some embodiments, the protective film layer 105 is an electroplated gold plating layer, and the thickness of the electroplated gold plating layer is 1 μm-3 μm. The electroplated nickel plating layer and the electroplated gold plating layer are compatible with lead-free solder and no-clean flux, suitable for multiple assembly processes, and solderability can be maintained for 12 months.
[0026] In some embodiments, the plastic film cover layer 101 is used to protect the first copper foil layer 102 from physical damage (such as scratches, abrasion, etc.), chemical corrosion (such as moisture, acidic or alkaline substances, etc.), and external environmental erosion (such as dust, other pollutants, etc.). The plastic film cover layer 101 is a polyimide film. The imide film has high insulation, which can effectively prevent short circuit between conductive circuits, ensure stable transmission of signals, and isolate external electrical interference. In some embodiments, the thickness of the plastic film cover layer 101 is 12.5 μm to 50 μm.
[0027] In some embodiments, the thickness of the first copper foil layer 102 and the second copper foil layer 104 is 45 μm to 65 μm.
[0028] In some embodiments, the substrate layer 103 is a polyimide substrate. The polyimide substrate has excellent high-temperature resistance (can withstand temperatures up to 260°C), good electrical insulation, high mechanical strength, excellent flexibility and fatigue resistance, etc., and is suitable for high-temperature environments (such as welding processes) and repeated bending applications, etc. In some embodiments, the thickness of the substrate layer 103 is 10 μm to 15 μm.
[0029] In some embodiments, the double-sided adhesive layer 106 can be an acrylic adhesive layer or a silicone adhesive layer, etc. The double-sided adhesive layer 106 is used to adhere to other components or surfaces of the electronic device. The thickness of the double-sided adhesive layer 106 can be specifically 8 μm to 12 μm.
[0030] In some embodiments, the total thickness of the flexible printed circuit board 100 is 140 μm to 150 μm. For example, in some embodiments of the present application, the total thickness of the flexible printed circuit board 100 is 145 μm.
[0031] Specifically, in some embodiments, the thickness of the plastic film cover layer 101 is 12.5 μm, the thickness of the first copper foil layer 102 is 55 μm, the thickness of the substrate layer 103 is 12.5 μm, the total thickness of the second copper foil layer 104 and the protective film layer 105 is 55 μm, and the thickness of the double-sided adhesive layer 106 is 10 μm. At this time, the total thickness of the flexible printed circuit board 100 is 145 μm.
[0032] In the second aspect of the present application, an electronic device is also provided, please refer to Figure 2 The electronic device 200 includes a main body 201 and a flexible printed circuit board 201 provided by the above embodiments; wherein the flexible printed circuit board 202 is installed on the main body 201.
[0033] In the embodiments of the present application, the flexible printed circuit board comprises a plastic film cover layer, a first copper foil layer, a substrate layer, a second copper foil layer, a protective film layer and a double-sided adhesive layer which are sequentially stacked; wherein the surface of the second copper foil layer close to the protective film layer is a bare copper surface, and the protective film layer is arranged on the bare copper surface. Generally, thinning the plastic film cover layer and the substrate layer can achieve the overall thickness reduction target, but thinning the cover film and the substrate thickness requires the selection of thinner unconventional materials, which is more expensive, and thinning the plastic film cover layer and the substrate layer will increase the risk of the flexible circuit board being punctured. Thinning the thickness of the first copper foil layer and the second copper foil layer can achieve the overall thickness reduction target, but thinning the copper foil thickness will result in reduced WPC performance. Therefore, the OSP layer, the electroplated nickel plating layer or the electroplated gold plating layer is used as the protective film layer in the embodiments of the application. Since the thickness of the OSP layer, the electroplated nickel plating layer or the electroplated gold plating layer is smaller than the thickness of the plastic film cover layer, compared with using the plastic film cover layer as the protective film layer of the bare copper surface of the second copper foil layer close to the protective film layer, the OSP layer, the electroplated nickel plating layer or the electroplated gold plating layer is used as the protective film layer in the embodiments of the present application can reduce the thickness of the flexible printed circuit board.
[0034] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be simple, they are not provided in details; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A flexible printed circuit board, characterized by, The flexible printed circuit board comprises a plastic film cover layer, a first copper foil layer, a substrate layer, a second copper foil layer, a protective film layer and a double-sided adhesive layer which are sequentially stacked. The surface of the second copper foil layer close to the side of the protective film layer is a bare copper surface, the protective film layer is arranged on the bare copper surface, and the protective film layer is an OSP layer, an electroplated nickel plating layer or an electroplated gold plating layer.
2. The flexible printed circuit board of claim 1, wherein, The protective film layer is an OSP layer, and the thickness of the OSP layer is 0.2 μm-0.5 μm.
3. The flexible printed circuit board of claim 1, wherein, The protective film layer is an electroplated nickel plating layer, and the thickness of the electroplated nickel plating layer is 3 μm-8 μm.
4. The flexible printed circuit board of claim 1, wherein, The protective film layer is an electroplated gold plating layer, and the thickness of the electroplated gold plating layer is 1 μm-3 μm.
5. The flexible printed circuit board according to any one of claims 1 to 4, characterized in that, The thickness of the plastic film cover layer is 12.5 μm-50 μm.
6. The flexible printed circuit board of claim 5, wherein, The plastic film cover layer is a polyimide film.
7. The flexible printed circuit board of claim 6, wherein, The thickness of the first copper foil layer and the second copper foil layer is 45 μm-65 μm.
8. The flexible printed circuit board of claim 5, wherein, The substrate layer is a polyimide substrate.
9. The flexible printed circuit board of claim 8, wherein, The thickness of the substrate layer is 10 μm-15 μm.
10. An electronic device, comprising: The electronic device comprises: a main body; and the flexible printed circuit board of any one of claims 1-9; wherein the flexible printed circuit board is mounted on the main body.