FPC welding sealing structure

Abstract

The utility model discloses an FPC (Flexible Printed Circuit) welding and sealing structure, which comprises an FPC board welded and overlapped with a PCB (Printed Circuit Board), a plurality of welding parts are formed between the FPC board and the PCB, a sealing isolation layer for sealing and surrounding the plurality of welding parts is arranged in an overlapped area between the FPC board and the PCB, and the sealing isolation layer is hermetically connected with the PCB and the PCB to form a closed sealing isolation area. The sealing isolation layer is a thermosetting adhesive structure bonded between the FPC board and the PCB, the thermosetting adhesive structure forms a compact protection layer after being cured, moisture and oxygen in air are isolated, welding spot oxidation or metal corrosion is prevented, the performance and reliability of the circuit assembly are improved, sealing isolation between the welding part and the outside is achieved, and the service life of the circuit assembly is prolonged. Therefore, the waterproof and dustproof effects on the welding position of the FPC board and the PCB are achieved, a key guarantee is provided for stable operation of the FPC board under complex working conditions, and the service life of the product is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of flexible printed circuit board technology, specifically to an FPC welding and sealing structure. Background Technology

[0002] With the development of information electronic products, FPC (generally referring to flexible circuit boards) is a widely used type of circuit board product. In particular, it has the characteristics of being thin, flexible, rollable, low voltage, low power consumption, and low power consumption. Through embedded circuit design, it can embed a large number of compact components in a limited space. The automotive battery modules on the market use FPC busbars to replace the traditional wire harness connection method in order to achieve the purpose of collecting information such as battery module voltage and temperature.

[0003] The connection between existing FPC boards and PCB boards is usually achieved using the HOTBAR process. This HOTBAR process uses hot pressing to melt the solder and connect the two electronic components that need to be connected. Typically, the flexible FPC is soldered onto the rigid PCB. The PCB has several gold fingers for soldering to the FPC, and the FPC has solder joints for connecting to the gold fingers. However, the solder joints connecting the FPC and PCB boards are exposed to the air and lack sealing measures. They are easily oxidized and corroded by the acid and humidity of the working environment, which can even cause short circuits between circuits, affecting product quality and safety. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to overcome the problem that the solder joints connecting the FPC board and the PCB board in the prior art are exposed to the air, which makes the solder joints prone to oxidation and corrosion, affecting product quality and safety.

[0005] To solve the above-mentioned technical problems, this utility model provides an FPC welding and sealing structure, including an FPC board that is stacked and connected to a PCB board. The FPC board and the PCB board are welded together to form multiple welding parts. The multiple welding parts are located in the overlapping area between the FPC board and the PCB board. A sealing isolation layer is provided in the overlapping area between the FPC board and the PCB board to seal and surround the multiple welding parts. The sealing isolation layer is sealed and connected to the FPC board and the PCB board to form a closed sealing isolation area.

[0006] As a preferred embodiment, the sealing and isolation layer is formed by curing a thermosetting adhesive structure bonded between the FPC board and the PCB board.

[0007] As a preferred embodiment, the thermosetting adhesive structure comprises a thermosetting adhesive that is bonded to the surfaces of the FPC board and the PCB board.

[0008] As a preferred embodiment, the thermosetting adhesive structure comprises a thermosetting adhesive film bonded to the surface of the FPC board and the PCB board.

[0009] As a preferred embodiment, the thickness of the sealing isolation layer is 0.1-0.5 mm.

[0010] As a preferred embodiment, the welding section includes a plurality of PCB pads disposed on the PCB board, and a plurality of FPC pads disposed on the FPC board corresponding to the plurality of PCB pads, wherein a layer of flux for hot-press welding of the FPC pads and the PCB pads is applied between the FPC pads and the PCB pads.

[0011] As a preferred embodiment, the FPC board includes a copper-based FPC body and protective films respectively attached to the front and back sides of the copper-based FPC body. The copper-based FPC body has multiple FPC pads formed in a sealed isolation area, and the protective film has multiple window structures that expose the multiple FPC pads.

[0012] As a preferred embodiment, the flux is solder paste, and through-holes are provided on the FPC pads. The solder paste passes through the through-holes and cools and solidifies on the back side of the copper-based FPC body to form an anchoring joint.

[0013] As a preferred embodiment, the back of the copper-based FPC body is provided with a sealing adhesive layer covering the FPC pads at the corresponding positions.

[0014] Compared with the prior art, the technical solution of this utility model has the following advantages:

[0015] 1. In the FPC welding sealing structure provided by this utility model, the FPC board and PCB board are connected by HOTBAR process (hot pressing welding), and multiple welding parts are formed between the FPC board and PCB board. The electrical connection between the FPC board and PCB board is achieved through multiple welding parts. In order to ensure the sealing performance of the welding point, before welding, a sealing isolation layer is set in the overlapping area between the FPC board and PCB board to seal and surround the multiple welding parts. The sealing isolation layer is connected to the FPC board and PCB board to form a closed sealing isolation area to prevent external impurities from entering the sealing isolation area. This setting achieves the sealing isolation between the welding part and the outside world, thereby playing a role in waterproofing and dustproofing the welding position of the FPC board and PCB board. By designing the sealing isolation layer, not only are the welding points protected and the sealing performance good, but it also becomes a key guarantee for the stable operation of FPC under complex working conditions, and improves the service life of the product.

[0016] 2. In the FPC welding sealing structure provided by this utility model, the sealing isolation layer is formed by the curing of a thermosetting adhesive structure bonded between the FPC board and the PCB board. The advantage of this design is that multiple welding positions of the FPC board are surrounded and sealed by thermosetting adhesive. After curing, this thermosetting adhesive structure forms a dense protective layer, which isolates moisture and oxygen in the air, prevents oxidation of the solder joints or corrosion of the metal, thereby improving the performance and reliability of the circuit components.

[0017] 3. In the FPC welding sealing structure provided by this utility model, the flux is preferably applied as solder paste between the FPC pads and the PCB pads. During the welding process, the solder paste passes through the through-hole and cools and solidifies on the back of the copper-based FPC body to form an anchoring joint, thereby increasing the mechanical strength of the solder joint and improving its tensile strength. A sealing adhesive layer is applied to the back of the copper-based FPC body to cover the FPC pads. The sealing adhesive layer seals the exposed FPC pads on the back, preventing them from being exposed and ensuring the sealing performance of the solder joints between the FPC board and the PCB board. Furthermore, after the sealing adhesive layer cures, it reduces solder joint breakage caused by vibration, drops, or external impacts, providing excellent sealing protection. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the stacked structure of the FPC welding sealing structure provided for the utility model;

[0020] Figure 2 This is a schematic diagram of the front structure of the FPC board of the utility model;

[0021] Figure 3 for Figure 2 A partially enlarged structural diagram of location A;

[0022] Figure 4 This is a schematic diagram of the welding structure between the FPC board and the PCB board of the utility model.

[0023] Figure descriptions: 1. FPC board; 2. PCB board; 3. Sealing isolation layer; 4. Sealing isolation area; 5. Soldering part; 6. FPC pad; 61. Through hole; 7. PCB pad; 8. Window structure; 9. Flux; 91. Anchoring joint. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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 also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0027] Example

[0028] This utility model provides, for example Figure 1-4 The diagram illustrates an FPC welding and sealing structure, comprising an FPC board 1 welded to a PCB board 2. The FPC board 1 and the PCB board 2 are welded together to form a plurality of welding parts 5, which are located in the overlapping area between the FPC board 1 and the PCB board 2. A sealing isolation layer 3 is provided in the overlapping area between the FPC board 1 and the PCB board 2 to seal and surround the plurality of welding parts 5. The sealing isolation layer 3 is sealed and connected to the FPC board 1 and the PCB board 2 to form a closed sealing isolation area 4, that is, the plurality of welding parts 5 are accommodated within the sealing isolation area 4.

[0029] The above-described implementation method is the core technical solution of this embodiment. The FPC board 1 and PCB board 2 are connected by a HOTBAR process (hot press welding), resulting in multiple welded sections 5 between them. These welded sections 5 provide electrical connection between the FPC board 1 and PCB board 2. To ensure the sealing of the solder joints of the multiple welded sections 5, a sealing isolation layer 3 is set in the overlapping area between the FPC board 1 and PCB board 2 before welding. This sealing isolation layer 3, connected to the FPC board 1 and PCB board 2, forms a closed sealing isolation area 4, preventing external impurities from entering. This design achieves sealing isolation between the welded sections 5 and the outside environment, thus providing waterproofing and dustproofing to the welding positions of the FPC board 1 and PCB board 2. The sealing isolation layer 3 not only protects the solder joints and provides good sealing performance, but also serves as a key guarantee for the stable operation of the FPC under complex working conditions, extending the product's service life.

[0030] The specific configuration of the sealing isolation layer 3 is described in detail below:

[0031] The sealing isolation layer 3 is formed by curing a thermosetting adhesive structure bonded between the FPC board 1 and the PCB board 2. The thickness of the sealing isolation layer 3 is 0.1-0.5mm, preferably 0.2mm. The advantage of this design is that multiple soldering positions of the FPC (flexible circuit board) are surrounded and sealed with thermosetting adhesive. The sealing isolation layer 3 can be rectangular, circular or other shapes to achieve the sealing and surrounding. After curing, this thermosetting adhesive structure forms a dense protective layer, which isolates moisture and oxygen in the air, prevents solder joint oxidation or metal corrosion, and improves the performance and reliability of the circuit components.

[0032] In a preferred embodiment, the thermosetting adhesive structure includes a thermosetting adhesive bonded to the surfaces of the FPC board 1 and the PCB board 2. This thermosetting adhesive is an adhesive using a thermosetting resin containing reactive groups as the binder. When a curing agent is added or heating is performed, the liquid binder molecules can further polymerize and crosslink into a three-dimensional network structure, forming an insoluble and infusible solid adhesive layer to achieve the purpose of bonding and sealing. After the thermosetting adhesive is cured, it is bonded to the surfaces of the FPC board 1 and the PCB board 2 to form a dense protective layer surrounding the multiple solder joints 5, thereby reliably ensuring the sealing of the multiple solder joints between the FPC board 1 and the PCB board 2.

[0033] In one adaptable embodiment, the thermosetting adhesive structure includes a thermosetting adhesive film adhered to the surfaces of the FPC board 1 and the PCB board 2. The thermosetting adhesive film is bonded to the opposite side surfaces of the FPC board 1 and the PCB board 2 around multiple solder joints 5. After curing, the thermosetting adhesive film forms a dense protective layer, effectively isolating oxygen and moisture in the air, preventing oxidation or moisture absorption of the solder joints during high-temperature soldering, and improving soldering reliability. Furthermore, this thermosetting adhesive film does not soften or decompose at high temperatures (such as reflow soldering and wave soldering), can withstand soldering temperatures, and ensures the sealing layer remains intact in subsequent processes. Those skilled in the art can select the specific configuration of the thermosetting adhesive structure based on the above description; other equivalent embodiments will not be elaborated upon here.

[0034] In this embodiment, as Figure 2-4 As shown, the soldering part 5 includes multiple PCB pads 7 disposed on the PCB board 2, and multiple FPC pads 6 disposed on the FPC board 1 corresponding to the multiple PCB pads 7. More preferably, the FPC board 1 includes a copper-based FPC body and protective films respectively attached to the front and back sides of the copper-based FPC body. The protective films provide insulation and protection for both sides of the copper-based FPC body. Multiple FPC pads 6 are formed on the copper-based FPC body and located within a sealed isolation area 4. Multiple window structures 8 are formed on the protective film to expose the multiple FPC pads 6. The corresponding multiple window structures 8 are also located within the sealed isolation area 4. The FPC pads 6 and PCB pads 7... A layer of flux 9 is applied between the two for hot-press welding. The function of the window structure 8 is to expose the FPC pad 6 for connecting the PCB pad 7. The FPC pad 6 and the corresponding PCB pad 7 are welded together at the position of the window structure 8 through the HOTBAR process. The HOTBAR process uses a precision hot press head to locally heat and pressurize the pads, which can achieve ultra-fine pitch welding of 0.1mm-0.3mm. It is suitable for high-density interconnection between FPC and PCB. With its high precision, low thermal stress and high reliability, the HOTBAR process is well-suited for FPC products with strict requirements for space, weight and flexibility, and significantly improves the durability and manufacturing efficiency of the products.

[0035] like Figure 4As shown, flux 9 is preferably applied as solder paste between PCB pad 7 and FPC pad 6. At least one through hole 61 is provided through the FPC pad 6. This through hole 61 can serve as a heat transfer channel, helping heat to be quickly conducted from the soldering surface to the back side, reducing local temperature differences, and avoiding warping or cold solder joints caused by thermal stress. During soldering heating, the molten solder penetrates to the other side of the FPC board through the through hole 61, filling the space inside the hole and forming an "anchoring effect". That is, the solder paste passes through the through hole 61 and cools and solidifies on the back side of the copper-based FPC body to form an anchoring joint 91, thereby increasing the mechanical strength of the solder joint, making the bonding area between the solder joint and the substrate larger, and significantly improving the tensile strength and fatigue resistance. It is suitable for scenarios with large vibration or temperature changes.

[0036] In a further preferred embodiment, the back of the copper-based FPC body is provided with a sealing adhesive layer (not shown in the attached figure) covering the FPC pad 6 at the position corresponding to the FPC pad 6. The FPC pad 6 is sealed by dispensing adhesive. The sealing adhesive layer seals the FPC pad 6 exposed on the back, preventing the FPC pad 6 from being exposed, thereby ensuring the sealing performance of the solder joints between the FPC board and the PCB board. Furthermore, after the sealing adhesive layer cures, it can reduce solder joint breakage caused by vibration, drops, or external impacts, and has a good sealing and protection effect.

[0037] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. An FPC solder sealing structure, comprising an FPC board (1) laminated with a PCB board (2) by thermal compression soldering, a plurality of soldering portions (5) being formed by soldering between the FPC board (1) and the PCB board (2), the plurality of soldering portions (5) being located in a lamination area between the FPC board (1) and the PCB board (2), a sealing isolation layer (3) being arranged in the lamination area between the FPC board (1) and the PCB board (2) and sealingly surrounding the plurality of soldering portions (5), the sealing isolation layer (3) being sealingly connected with the FPC board (1) and the PCB board (2) to form a closed sealing isolation area (4).

2. The FPC weld seal structure of claim 1, wherein: The sealing isolation layer (3) is a thermosetting adhesive structure solidified between the FPC board (1) and the PCB board (2).

3. The FPC weld seal structure of claim 2, wherein: The thermosetting adhesive structure comprises a thermosetting adhesive agent adhered to surfaces of the FPC board (1) and the PCB board (2).

4. The FPC weld seal structure of claim 2, wherein: The thermosetting adhesive structure comprises a thermosetting adhesive film adhered to surfaces of the FPC board (1) and the PCB board (2).

5. The FPC weld seal structure of claim 1, wherein: The sealing isolation layer (3) has a thickness of 0.1-0.5 mm.

6. The FPC solder seal structure of any of claims 1-5, wherein: The soldering portion (5) comprises a plurality of PCB pads (7) arranged on the PCB board (2) and a plurality of FPC pads (6) arranged on the FPC board (1) corresponding to the plurality of PCB pads (7), a layer of soldering flux (9) being coated between the FPC pads (6) and the PCB pads (7) for thermal compression soldering.

7. The FPC weld seal structure of claim 6, wherein: The FPC board (1) comprises a copper-based FPC body and protective films respectively adhered to front and back surfaces of the copper-based FPC body, a plurality of FPC pads (6) being formed on the copper-based FPC body and located in the sealing isolation area (4), and a plurality of window structures (8) being formed on the protective films and exposing the plurality of FPC pads (6).

8. The FPC weld seal structure of claim 7, wherein: The soldering flux (9) is a tin paste, at least one through-tin hole (61) being arranged on the FPC pad (6), and the tin paste being cooled and solidified on the back surface of the copper-based FPC body through the through-tin hole (61) to form an anchoring bonding portion (91).

9. The FPC weld seal structure of claim 8, wherein: The back surface of the copper-based FPC body is provided with a sealing point gluing layer covering the FPC pad (6) at a position corresponding to the FPC pad (6).

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