Reinforcing plate mounting method, flexible circuit board and battery

Abstract

The invention relates to the technical field of flexible circuit boards, in particular to a mounting method of a reinforcing plate, a flexible circuit board and a battery. The mounting method of the reinforcing plate comprises the following steps: S1, generating a circuit and a bonding pad of an element on the upper surface of a substrate of the flexible circuit board, and arranging a first welding layer around the circumferential direction of the bonding pad; and S2, pasting a cover film on the upper surface of the base material, and performing windowing treatment on the cover film to form a first window for exposing the bonding pad and a second window for exposing the first welding layer. And S3, generating a first solder paste layer on the first welding layer. S4, preparing a reinforcing plate, and processing a through hole opposite to the first window in the reinforcing plate so as to expose the bonding pad; the reinforcing plate comprises an FR4 mother plate and a second welding layer; the FR4 mother board is welded on the first welding layer through the second welding layer. The reinforcing plate is welded to the base material of the flexible circuit board in a surface mounting manner, so that the mounting efficiency of the reinforcing plate is improved. And meanwhile, welding breakage of the reinforcing plate in the thermocompression bonding process is avoided, and the product yield is increased.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board technology, and in particular to a method for mounting a reinforcing plate, a flexible circuit board, and a battery. Background Technology

[0002] To enhance the mechanical strength and stability of the negative temperature coefficient thermistors on flexible circuit boards, protect them from external damage, and extend their service life, a reinforcing plate made of FR4 material in a U-shape is mounted on the negative temperature coefficient thermistor.

[0003] In related reinforcement plate mounting technologies, thermosetting adhesive is typically applied to the surface of the reinforcement plate, and it is then fixed to a substrate containing a negative temperature coefficient thermistor within a flexible circuit board using a thermosetting bonding method. The specific mounting process includes pressing, baking, and dispensing, resulting in a lengthy mounting process and low bonding efficiency. Furthermore, the reinforcement plate is prone to weld breakage during thermosetting, leading to functional failures during final testing of the flexible circuit board and ultimately resulting in scrap, thus reducing product yield. Summary of the Invention

[0004] The purpose of this invention is to provide a method for mounting a reinforcing plate, a flexible circuit board, and a battery, so as to improve the mounting efficiency of the reinforcing plate on the flexible circuit board and improve the product yield of the flexible circuit board.

[0005] To achieve this objective, the technical solution adopted by the present invention is as follows: A method for mounting a reinforcing plate, wherein the reinforcing plate is mounted on a flexible circuit board, the method comprising the following steps: S1: The circuits and pads of the components to be soldered are generated on the upper surface of the substrate of the flexible circuit board, and a first solder layer is arranged around the pads in a circumferential direction. S2: A cover film is attached to the upper surface of the substrate, and the cover film is windowed to form a first window exposing the pads and a second window exposing the first solder layer. S3: A first solder paste layer is generated in the first solder layer; S4: Prepare the reinforcing plate, and process through holes in the reinforcing plate that are opposite to the first window to expose the pads; the reinforcing plate includes an FR4 mother plate and a second welding layer disposed on the lower surface of the FR4 mother plate; the FR4 mother plate is welded to the first welding layer through the second welding layer.

[0006] As an alternative method for mounting the reinforcing plate, in step S1, the first welding layer has at least a clearance opening through which the wiring passes.

[0007] As an alternative method for mounting the reinforcing plate, in step S3, solder paste is printed onto the first solder layer by screen printing to form the first solder paste layer.

[0008] As an alternative method for mounting the reinforcing plate, a second solder paste layer is applied to the surface of the second solder layer during the preparation of the reinforcing plate.

[0009] As an alternative method for mounting the reinforcing plate, in step S4, the prepared reinforcing plate is mounted onto the first welding layer using a pick-and-place machine, and the second welding layer is welded to the first welding layer.

[0010] As an alternative method for mounting the reinforcing plate, in step S4, the second welding layer is welded to the first welding layer by reflow soldering.

[0011] As an alternative method for mounting the reinforcing plate, in step S2, the projection of the first welding layer falls entirely within the second window along the thickness direction of the flexible circuit board.

[0012] As an optional method for mounting the reinforcing plate, the distance between the inner edge of the second window and the outer edge of the first welding layer is 0.2mm-0.3mm.

[0013] A flexible circuit board, comprising a substrate, a cover film, and a reinforcing plate, wherein the reinforcing plate is attached to the substrate by the aforementioned reinforcing plate mounting method.

[0014] The battery includes the aforementioned flexible circuit board.

[0015] The beneficial effects of this invention are as follows: The reinforcing plate mounting method proposed in this invention includes the following steps: In step S1, circuits and pads of the components to be soldered are generated on the upper surface of the substrate of the flexible circuit board, and a first solder layer is arranged circumferentially around the pads. In step S2, a cover film is applied to the upper surface of the substrate, and the cover film is windowed to form a first window exposing the pads and a second window exposing the first solder layer. In step S3, a first solder paste layer is generated on the first solder layer. In step S4, a reinforcing plate is prepared, and through holes are machined on the reinforcing plate opposite to the first window to expose the pads; the reinforcing plate includes an FR4 motherboard and a second solder layer disposed on the lower surface of the FR4 motherboard; the FR4 motherboard is soldered to the first solder layer through the second solder layer. The reinforcing plate is surface-mounted onto the substrate of the flexible circuit board without the need for a thermo-pressing process (i.e., bonding-pressing-baking), simplifying the installation process of the reinforcing plate and improving the mounting efficiency of the reinforcing plate on the flexible circuit board. Simultaneously, it avoids solder fracture of the reinforcing plate during thermo-pressing, improving the product yield of the flexible circuit board.

[0016] The reinforcing plate in the flexible circuit board proposed in this invention is attached to the substrate of the flexible circuit board by the above-mentioned mounting method, which simplifies the installation process of the reinforcing plate and avoids welding breakage of the reinforcing plate during the hot pressing process, thereby improving the production efficiency and product yield of the flexible circuit board.

[0017] The battery proposed in this invention includes the aforementioned flexible circuit board, which improves battery production efficiency and product yield. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the substrate (having lines, pads and a first solder layer) of the flexible circuit board provided in the embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the flexible circuit board provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the reinforcing plate provided in an embodiment of the present invention; Figure 4 This is a flowchart of the reinforcement plate mounting method provided in the embodiments of the present invention; Figure 5 This is a cross-sectional view of the reinforcing plate provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a flexible circuit board with a first solder paste layer provided in an embodiment of the present invention.

[0019] The component names and labels in the diagram are as follows: 1. Substrate; 11. Circuit; 12. Pad; 13. First solder layer; 130. Clearance opening; 2. Cover film; 21. Second window; 3. First solder paste layer; 4. Reinforcing plate; 40. Through hole; 41. FR4 motherboard; 42. Second solder layer; 43. Second solder paste layer. Detailed Implementation

[0020] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 and Figure 2 As shown, this embodiment proposes a flexible circuit board, which includes a substrate 1 and a cover film 2. The upper surface of the substrate 1 is provided with lines 11 and pads 12 for components to be soldered. The cover film 2 is attached to the upper surface of the substrate 1. The cover film 2 needs to be windowed to form windows exposing the pads 12, so that components can be soldered to the pads 12, thereby electrically connecting the components to the lines 11 of the substrate 1. In this embodiment, the component is a negative temperature coefficient thermistor. In other embodiments, the component may be other electrical components, which are not specifically limited here.

[0026] like Figure 3As shown, to enhance the mechanical strength and stability of the negative temperature coefficient (NTC) thermistor on the flexible circuit board, protect it from external damage, and extend its service life, a reinforcing plate 4 is mounted on the NTC thermistor. The reinforcing plate 4 has a U-shaped structure and through holes 40. When the reinforcing plate 4 is mounted on the substrate 1, the pads 12 are exposed through the through holes 40 to ensure smooth soldering and mounting of components at the pads 12.

[0027] Existing reinforcing plates typically involve coating their surface with thermosetting adhesive during substrate assembly and then using thermoforming to fix them onto the substrate containing negative temperature coefficient thermistors within the flexible circuit board. This assembly process includes pressing, baking, and dispensing, resulting in a lengthy and inefficient process. Furthermore, the reinforcing plates are prone to weld breakage during thermoforming, leading to functional failures during final testing of the flexible circuit board and ultimately resulting in scrap, thus reducing product yield.

[0028] To solve the above problems, such as Figures 4-6 As shown, this embodiment also proposes a method for mounting a reinforcing plate 4 onto a flexible circuit board. The mounting method includes the following steps: S1: Forming lines 11 and pads 12 of the components to be soldered on the upper surface of the substrate 1 of the flexible circuit board, and arranging a first solder layer 13 circumferentially around the pads 12. S2: Covering the upper surface of the substrate 1 with a cover film 2, the cover film 2 being windowed to form a first window exposing the pads 12 and a second window 21 exposing the first solder layer 13. S3: Forming a first solder paste layer 3 on the first solder layer 13. S4: Preparing the reinforcing plate 4, and machining through holes 40 opposite to the first window on the reinforcing plate 4 to expose the pads 12. The reinforcing plate 4 includes an FR4 motherboard 41 and a second solder layer 42 disposed on the lower surface of the FR4 motherboard 41. The FR4 motherboard 41 is soldered to the first solder layer 13 through the second solder layer 42. The reinforcing plate 4 is surface-mounted onto the substrate 1 of the flexible circuit board, eliminating the need for a thermoforming process (i.e., bonding-pressing-baking). This simplifies the installation process of the reinforcing plate 4 and improves its mounting efficiency on the flexible circuit board. Simultaneously, it prevents weld breakage of the reinforcing plate 4 during the thermoforming process, thus improving the product yield of the flexible circuit board.

[0029] like Figure 1 As shown, in step S1, the first welding layer 13 has at least a clearance opening 130 through which the line 11 passes. By providing the clearance opening 130, it is convenient to arrange the line 11 reasonably on the upper surface of the substrate 1, and to avoid interference between the line 11 and the reinforcing plate 4.

[0030] like Figure 2As shown, in step S2, the projection of the first welding layer 13 along the thickness direction of the flexible circuit board falls entirely within the second window 21. This arrangement ensures that the opening area of ​​the second window 21 is larger than the area of ​​the first welding layer 13. Even if the cover film 2 experiences a certain adhesion deviation when adhering to the substrate 1, it can still guarantee that the first welding layer 13 is fully exposed through the second window 21, facilitating the smooth welding of the reinforcing plate 4.

[0031] It should be noted that the distance between the inner edge of the second window 21 and the outer edge of the first welding layer 13 is 0.2mm-0.3mm. This ensures that the second window 21 has a suitable opening area, avoiding the situation where the opening area of ​​the second window 21 is too small, resulting in part of the first welding layer 13 not being fully exposed, while also avoiding the situation where the opening area of ​​the second window 21 is too large, affecting the arrangement of the circuits 11 and components on the substrate 1.

[0032] In this embodiment, a first solder layer 13 is formed around the solder pad 12. The first solder layer 13 is specifically a copper layer, which not only allows the first solder layer 13 to be better arranged on the substrate 1 of the flexible circuit board, but also makes the first solder layer 13 have good soldering performance, so as to improve the soldering quality between the reinforcing plate 4 and the first solder layer 13.

[0033] In this embodiment, the reinforcing plate 4 can be directly made of copper-clad laminate, which not only simplifies the manufacturing process of the reinforcing plate 4 and reduces its cost, but also gives the reinforcing plate 4 a comprehensive advantage of electrical reliability, mechanical strength, thermal stability, flame retardancy, and cost control. Moreover, the FR4 motherboard 41 of the reinforcing plate 4 is the substrate layer of the copper-clad laminate (i.e., it is composed of the resin insulation layer and the reinforcing material layer of the copper-clad laminate), and the second welding layer 42 of the reinforcing plate 4 is the copper layer of the copper-clad laminate, so that both the second welding layer 42 and the first welding layer 13 are copper layers, so as to achieve good welding between the two and further improve the welding quality of the reinforcing plate 4.

[0034] Furthermore, such as Figure 5 As shown, during the fabrication of the reinforcing plate 4, a second solder paste layer 43 is coated on the surface of the second welding layer 42, so that the copper layer of the copper-clad laminate is coated with a solder paste layer to prevent oxidation of the copper layer. The solder paste layer also acts as a flux. When the first welding layer 13 is welded to the second welding layer 42, a copper-tin alloy layer is formed to improve the welding strength and welding stability of the reinforcing plate 4.

[0035] like Figure 6 As shown, in step S3, solder paste is printed onto the first solder layer 13 by screen printing to form the first solder paste layer 3. The screen printing process ensures high precision in solder paste coating, guaranteeing the stability and consistency of solder paste coating quality.

[0036] In this embodiment, in step S4, the prepared reinforcing plate 4 is bonded and installed onto the first welding layer 13 using a pick-and-place machine, and the second welding layer 42 is welded to the first welding layer 13. By using the pick-and-place machine, the reinforcing plate 4 is precisely transferred from the storage hopper to the flexible circuit board, automatically connecting the previous screen printing process with the subsequent welding process. This allows the reinforcing plate 4 to be accurately and efficiently mounted onto the first welding layer 13, achieving automatic feeding and welding of the reinforcing plate 4, thereby improving the mounting efficiency of the reinforcing plate 4 on the flexible circuit board. Since the pick-and-place machine is existing equipment, its specific structure and working process will not be described in detail.

[0037] It should be noted that in step S4, the second solder layer 42 is soldered to the first solder layer 13 by reflow soldering.

[0038] This embodiment also proposes a battery, which includes the aforementioned flexible circuit board. The reinforcing plate 4 is attached to the substrate 1 by the aforementioned reinforcing plate mounting method, thereby improving the production efficiency and product yield of the flexible circuit board, and thus improving the production efficiency and product yield of the battery.

[0039] The above embodiments merely illustrate the basic principles and characteristics of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for mounting reinforcing plates, characterized in that, The reinforcing plate (4) is mounted on the flexible circuit board, and the mounting method of the reinforcing plate includes the following steps: S1: The lines (11) and pads (12) of the components to be soldered are generated on the upper surface of the substrate (1) of the flexible circuit board, and a first solder layer (13) is arranged around the pads (12) in a circumferential direction. S2: A cover film (2) is attached to the upper surface of the substrate (1). The cover film (2) is windowed to form a first window exposing the pad (12) and a second window (21) exposing the first solder layer (13). S3: A first solder paste layer (3) is formed on the first solder layer (13); S4: Prepare the reinforcing plate (4), and process a through hole (40) opposite to the first window in the reinforcing plate (4) to expose the pad (12); the reinforcing plate (4) includes an FR4 mother plate (41) and a second welding layer (42) disposed on the lower surface of the FR4 mother plate (41); the FR4 mother plate (41) is welded to the first welding layer (13) through the second welding layer (42).

2. The method for attaching the reinforcing plate according to claim 1, characterized in that, In step S1, the first solder layer (13) has at least a clearance opening (130) through which the line (11) passes.

3. The method for attaching the reinforcing plate according to claim 1, characterized in that, In step S3, solder paste is printed onto the first solder layer (13) by screen printing to form the first solder paste layer (3).

4. The method for attaching the reinforcing plate according to claim 1, characterized in that, When preparing the reinforcing plate (4), a second solder paste layer (43) is applied to the surface of the second solder layer (42).

5. The method for attaching the reinforcing plate according to claim 4, characterized in that, In step S4, the prepared reinforcing plate (4) is bonded and installed onto the first welding layer (13) by a patching machine, and the second welding layer (42) is welded to the first welding layer (13).

6. The method for attaching the reinforcing plate according to claim 5, characterized in that, In step S4, the second solder layer (42) is soldered to the first solder layer (13) by reflow soldering.

7. The method for mounting the reinforcing plate according to any one of claims 1-6, characterized in that, In step S2, along the thickness direction of the flexible circuit board, the projection of the first welding layer (13) falls entirely within the second window (21).

8. The method for attaching the reinforcing plate according to claim 7, characterized in that, The distance between the inner edge of the second window (21) and the outer edge of the first weld layer (13) is 0.2mm-0.3mm.

9. A flexible circuit board, characterized in that, The flexible circuit board includes a substrate (1), a cover film (2), and a reinforcing plate (4), wherein the reinforcing plate (4) is attached to the substrate (1) by the mounting method of the reinforcing plate according to any one of claims 1-8.

10. A battery, characterized in that, Includes the flexible circuit board as described in claim 9.

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