A soldering method and a soldering apparatus for a circuit board assembly

Abstract

The application relates to the technical field of welding, and provides a welding method and a welding device for a circuit board assembly. The welding method comprises the following steps: placing a first circuit board on a supporting tool, wherein the first circuit board comprises two or more first welding areas; stacking a second circuit board on the first circuit board, wherein the second circuit board comprises two or more second welding areas; arranging a pressing plate assembly on the second circuit board to weld the two or more first welding areas and the two or more second welding areas; wherein at least one of the first circuit board and the second circuit board is a circuit board spliced board, the circuit board spliced board comprises a splicing structure and N circuit board single boards spliced with each other; and the splicing structure connected with the circuit board single boards is cut to form a circuit board assembly containing the circuit board single boards. The welding method can realize welding of one circuit board and multiple circuit boards or welding of multiple circuit boards and multiple circuit boards, and the welding efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of welding technology, and in particular to a welding method and a welding device for a circuit board assembly. Background Art

[0002] In various scenarios such as modern life and work communication, the role of mobile terminals such as smart watches, mobile phones, and laptops is becoming increasingly important and has gradually become one of the necessities of modern people's lives.

[0003] Taking smart watches as an example, smart watches include components such as batteries, main boards, screen assemblies and housings (also referred to as middle frames). The batteries, main boards and screen assemblies are arranged in the housing. The main board is usually a printed circuit board (PCB), which includes but is not limited to various components such as processors, antenna modules, Bluetooth modules, WiFi modules, GPS modules, power supplies, charging modules, screen display and operation modules. Some components on smart watches need to be electrically connected to certain components on the main board to achieve corresponding functions. Some components on smart watches are usually electrically connected to components on the main board through flexible printed circuits (FPCs). For example, the screen assembly needs to be electrically connected to the screen display and operation module on the main board (PCB) through a flexible printed circuit board (FPC) so that the screen assembly can achieve display or operation functions.

[0004] With the diversification of mobile terminal functions, there are more and more functional components in mobile terminals, and more and more corresponding components are integrated on the motherboard. This involves scenarios where one flexible circuit board (FPC) is connected to multiple motherboards (PCBs), or multiple flexible circuit boards (FPCs) are connected to one motherboard (PCB), or multiple flexible circuit boards (FPCs) are connected to multiple motherboards (PCBs).

[0005] The flexible printed circuit board (FPC) and the main board (PCB) can be welded together using laser welding technology to achieve electrical connection. The existing welding method usually welds one flexible printed circuit board (FPC) and one main board (PCB) together, which leads to low welding efficiency. Summary of the Invention

[0006] An embodiment of the present application provides a welding method for a circuit board assembly (for example, including an FPC and a PCB), which can realize welding of one flexible circuit board (FPC) with multiple main boards (PCBs), or realize welding of multiple flexible circuit boards (FPCs) with one main board (PCB), or realize welding of multiple flexible circuit boards (FPCs) with multiple main boards (PCBs), thereby improving welding efficiency.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a method for soldering a circuit board assembly. The method is applied to a soldering device including a chassis, a support fixture, and a pressure plate assembly. The support fixture is supported on the chassis and is located between the pressure plate assembly and the chassis. The method includes:

[0009] Placing a first circuit board on the supporting tool, wherein the first circuit board includes more than two first welding areas, and the more than two first welding areas face the pressing plate assembly;

[0010] A second circuit board is stacked on the first circuit board, wherein the second circuit board includes two or more second welding areas, and the two or more second welding areas correspond to the two or more first welding areas in a one-to-one manner;

[0011] The pressing plate assembly is pressed on the second circuit board to weld and connect two or more first welding areas and two or more second welding areas; wherein,

[0012] At least one of the first circuit board and the second circuit board is a circuit board panel, the circuit board panel including a splicing structure and N circuit board sheets spliced ​​together, where N is a positive integer and N ≥ 2, the splicing structure connects two adjacent circuit board sheets, and each circuit board sheet is provided with a welding area;

[0013] The splicing structure connected to the circuit board single board is cut to form a circuit board assembly including the circuit board single board.

[0014] In an embodiment of the present application, a circuit board panel is placed on a supporting tooling, and the circuit board panel includes multiple circuit board single boards. After the circuit board panel and a circuit board (such as FPC) are welded together, a panel separation operation is performed to realize a welding connection between a second circuit board (including at least two welding areas) and multiple circuit board single boards, thereby improving the welding efficiency of the circuit board assembly.

[0015] In a possible implementation of the first aspect above, the first circuit board is a circuit board panel, and the second circuit board is a continuous circuit board; or, the second circuit board is a circuit board panel, and the first circuit board is a continuous circuit board; or, the first circuit board is a circuit board panel, and the second circuit board is a circuit board panel, and each circuit board single board in the first circuit board corresponds one-to-one to each circuit board single board in the second circuit board.

[0016] In a possible implementation of the first aspect described above, glue is dispensed at a set distance from the edge of the first welding area; after the second circuit board is stacked on the first circuit board, the circuit board assembly is heated to solidify the glue between the first circuit board and the second circuit board.

[0017] In a possible implementation of the first aspect, the first circuit board is disposed on the second circuit board, and the first circuit board is disposed on the second circuit board by means of dispensing glue on the periphery edge of the first welding area.

[0018] In a possible implementation of the first aspect, the second circuit board is provided with a dispensing hole, the dispensing hole penetrates the second circuit board, and the dispensing hole is arranged at a distance from the edge of the second welding area; after the first circuit board is placed on the second circuit board in a stacked manner, the dispensing hole is filled with glue, the circuit board assembly is heated, and the glue between the first circuit board and the second circuit board is solidified.

[0019] In a possible implementation of the first aspect, the distance is 0.2 mm to 10 mm.

[0020] In a possible implementation of the first aspect, the heating temperature of the circuit board assembly is 150°C to 220°C.

[0021] In a possible implementation of the first aspect, one of the first welding area and the second welding area includes at least two rows of pads, and the other includes welding pins connected to the at least two rows of pads by welding;

[0022] Each row of pads extends along a first direction, and two adjacent rows of pads are arranged at intervals along a second direction, the first direction and the second direction intersect, and a row of pads includes a plurality of pads arranged at intervals along the first direction;

[0023] The welding pin includes a central hole extending along a third direction.

[0024] In a possible implementation of the first aspect, the size of each row of pads along the first direction is between 40 mm and 200 mm, and the diameter of each pad is between 0.3 mm and 3 mm; the diameter of the central hole is between 0.075 mm and 0.15 mm.

[0025] In a possible implementation of the first aspect, along the first direction, the ratio of the gap between adjacent pads to the size of a single pad along the first direction is between 1 / 3 and 3 / 2, and along the second direction, the ratio of the gap between adjacent pads to the size of a single pad along the second direction is between 1 / 3 and 3 / 2.

[0026] In a possible implementation of the first aspect, the circuit board single board is provided with a board separation line, the splicing structure is connected to the board separation line, and the distance between the board separation line and the welding area on the circuit board single board is between 0.1 mm and 2 mm.

[0027] In a possible implementation of the first aspect, the first circuit board is provided with one or more first positioning holes, and the second circuit board is provided with second positioning holes corresponding to the first positioning holes;

[0028] The first positioning hole of the first circuit board penetrates the first positioning pin on the support tooling, and the first circuit board is placed on the support tooling.

[0029] The second positioning hole of the second circuit board passes through the first positioning pin on the supporting fixture and is then placed on the first circuit board.

[0030] In a possible implementation of the first aspect above, the circuit board assemblies are of unequal thickness, and unequal thickness pressing spaces are formed between the pressure plate assembly and the supporting tooling of the welding device, and the unequal thickness pressing spaces are shaped like the unequal thickness circuit board assemblies; the welding method includes: placing the circuit board assembly in the unequal thickness pressing spaces, and pressing the circuit board assembly through the unequal thickness pressing spaces.

[0031] In a possible implementation of the first aspect above, the first circuit board and / or the second circuit board are circuit boards of unequal thickness.

[0032] In a possible implementation of the first aspect, the first circuit board includes at least a thick section and a thin section of the circuit board having different thicknesses; the supporting fixture includes a low-end supporting portion and a high-end supporting portion, and along the direction from the supporting fixture toward the pressure plate assembly, the high-end supporting portion is higher than the low-end supporting portion; the pressure plate assembly includes a low-end pressure plate and a high-end pressure plate, and along the direction from the pressure plate assembly toward the supporting fixture, the high-end pressure plate is higher than the low-end pressure plate, the low-end pressure plate corresponds to the low-end supporting portion, and the high-end pressure plate corresponds to the high-end supporting portion;

[0033] The thick section of the first circuit board is placed on the low-end support part, the thin section of the first circuit board is placed on the high-end support part, the low-end pressure plate is pressed on the part of the second circuit board corresponding to the thick section of the first circuit board, and the high-end pressure plate is pressed on the part of the second circuit board corresponding to the thin section of the first circuit board.

[0034] In a possible implementation of the first aspect, the soldering area of ​​the thick circuit board and the soldering area of ​​the thin circuit board are not in the same plane.

[0035] In a possible implementation of the first aspect above, one of the first circuit board and the second circuit board is a printed circuit board, and the other is a flexible circuit board; or both the first circuit board and the second circuit board are flexible circuit boards; or both the first circuit board and the second circuit board are printed circuit boards.

[0036] In a possible implementation of the first aspect, the thickness of the flexible circuit board is between 0.07 mm and 0.5 mm.

[0037] In a possible implementation of the first aspect, the circuit board assembly is heated by infrared laser to weld and connect two or more first welding areas and two or more second welding areas; and the spliced ​​structure is cut by ultraviolet laser.

[0038] In a possible implementation of the first aspect above, the first welding area includes a welding pin, the welding pin includes a center hole extending along the stacking direction, the center hole includes: a first section, a second section and a third section connected in sequence along the stacking direction, the aperture of the first section is larger than the aperture of the second section, and the aperture of the third section is larger than the aperture of the second section; the second circuit boards (for example, PCBs) are welded on opposite sides of the stacking direction of the first circuit board, and the second welding area of ​​the second circuit board includes a soldering pad welded to the soldering pin, wherein one of the soldering pads of the second circuit board is welded to the first section of the soldering pin, and the other soldering pad of the second circuit board is welded to the third section of the soldering pin.

[0039] Exemplarily, the first circuit board is an FPC, and the center hole of the first welding area of ​​the FPC is a double-sided large hole (the first and third sections are holes with large apertures in the center hole) and a small hole in the middle (the second section is a hole with small apertures in the center hole). Exemplarily, the aperture of the small hole in the middle (the second section of the center hole) is smaller than the diameter of the solder particles, for example, smaller than the diameters of two solder particles, so that the tin printed on the FPC does not flow through to the other side. That is, when solder is placed in the first section on one side of the FPC, the solder will not flow down from the second section to the third section. After the FPC and the PCB on that side are welded, there will be no solder on the other side of the FPC, and the height of the other side of the FPC will not increase. Therefore, after solder is placed in the third section on the other side of the FPC, the PCB can be welded to the FPC normally.

[0040] In a possible implementation of the first aspect above, the two second circuit boards overlap in a stacking direction.

[0041] In a possible implementation of the first aspect above, the first welding area includes a first welding pin and a second welding pin, the first welding pin and the second welding pin respectively include a center hole extending along the stacking direction, the center hole of the first welding pin includes a first section and a second section connected along the stacking direction, and the aperture of the first section of the first welding pin is larger than the aperture of the second section; the center hole of the second welding pin includes a first section and a second section connected along the stacking direction, and the aperture of the first section of the second welding pin is larger than the aperture of the second section; the second circuit boards are welded on opposite sides of the stacking direction of the first circuit board, and the second welding area of ​​the second circuit board includes pads welded to the welding pins, wherein one pad of the second circuit board is welded to the first section of the first welding pin, and the other pad of the second circuit board is welded to the first section of the welding pin.

[0042] In a possible implementation of the first aspect above, the two second circuit boards are staggered in the stacking direction.

[0043] Exemplarily, the first circuit board is an FPC, and the center hole of the first welding pin of the first welding area of ​​the FPC is a large hole on one side (the first section of the center hole) and a small hole on the other side (the second section of the center hole); the center hole of the second welding pin of the first welding area of ​​the FPC is a large hole on one side (the first section of the center hole) and a small hole on the other side (the second section of the center hole), the first section of the first welding pin and the first section of the second welding pin are located on opposite sides of the FPC, and the second section of the first welding pin and the second section of the second welding pin are located on opposite sides of the FPC.

[0044] The aperture (the second section of the center hole) is smaller than the diameter of the solder particles—for example, smaller than the diameter of two solder particles—to prevent the printed solder from seeping through to the other side of the FPC. That is, when solder is placed in the first section on one side of the FPC, it won't flow down through the second section to the other side of the FPC. Consequently, the height of the FPC on the other side will remain unchanged, and the FPC's height will not increase. Consequently, after solder is placed in the first section on the other side of the FPC, the PCB and FPC can be soldered normally. This allows for simultaneous soldering of FPCs with misaligned sides.

[0045] In a second aspect, an embodiment of the present application provides a welding device, comprising: a chassis, a supporting tool, and a pressure plate assembly;

[0046] The supporting tooling is supported on the chassis, and along the height direction, the supporting tooling is located between the pressure plate assembly and the chassis;

[0047] The supporting fixture is used to place a circuit board assembly, the circuit board assembly includes a first circuit board and a second circuit board stacked on the first circuit board, the first circuit board includes two or more first welding areas, the two or more first welding areas face the pressure plate assembly, and the second circuit board includes two or more second welding areas, the two or more second welding areas correspond one-to-one to the two or more first welding areas;

[0048] The pressing plate assembly is used for pressing the second circuit board;

[0049] At least one of the first circuit board and the second circuit board is a circuit board panel, the circuit board panel includes a splicing structure and N circuit board sheets spliced ​​together, N is a positive integer, and N ≥ 2, the splicing structure connects two adjacent circuit board sheets, and each circuit board sheet is provided with a welding area;

[0050] The cutting device is used to cut the splicing structure connected to the circuit board.

[0051] In a possible implementation of the second aspect above, it further includes: a laser, which is arranged on the side of the pressure plate assembly facing away from the chassis, and the laser emitted by the laser can pass through the pressure plate assembly to irradiate the circuit board assembly on the supporting tooling.

[0052] In a possible implementation of the second aspect, the cutting device includes an ultraviolet laser, and the ultraviolet laser emitted by the ultraviolet laser cuts the splicing structure connected to the circuit board.

[0053] In a possible implementation of the second aspect above, the ultraviolet laser is disposed on a side of the pressure plate assembly facing away from the chassis.

[0054] In a possible implementation of the second aspect above, the circuit board assemblies are of unequal thickness, and unequal thickness pressing spaces are formed between the pressure plate assembly and the supporting tooling, and the unequal thickness pressing spaces are shaped like the circuit board assemblies of unequal thickness; the unequal thickness pressing spaces are used to place circuit board assemblies of unequal thickness and press the circuit board assemblies of unequal thickness.

[0055] In a possible implementation of the second aspect above,

[0056] The supporting tooling includes a low-end supporting portion and a high-end supporting portion, and along the direction from the supporting tooling toward the pressure plate assembly, the high-end supporting portion is higher than the low-end supporting portion;

[0057] The pressure plate assembly includes a low-end pressure plate and a high-end pressure plate. Along the direction from the pressure plate assembly toward the supporting tooling, the high-end pressure plate is higher than the low-end pressure plate. The low-end pressure plate corresponds to the low-end support part, and the high-end pressure plate corresponds to the high-end support part to form unequal thickness pressing spaces.

[0058] In a possible implementation of the second aspect, the first circuit board includes at least a thick circuit board segment and a thin circuit board segment having different thicknesses;

[0059] The low-end support portion is used to place the thick section of the first circuit board, and the high-end support portion is used to place the thin section of the first circuit board;

[0060] The low-end pressing plate is used to press the portion of the second circuit board corresponding to the thick section of the first circuit board, and the high-end pressing plate is used to press the portion of the second circuit board corresponding to the thin section of the first circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 According to some embodiments of the present application, a schematic diagram of the structure of a circuit board assembly is shown. Figure 1 ;

[0062] Figure 2 According to some embodiments of the present application, a schematic diagram of the structure of a circuit board assembly is shown. Figure 2 ;

[0063] Figure 3 According to some embodiments of the present application, a schematic diagram of the structure of a circuit board assembly is shown. Figure 3 ;

[0064] Figure 4According to some embodiments of the present application, a schematic diagram of the structure of a welding device is shown. Figure 1 ;

[0065] Figure 5a According to some embodiments of the present application, a flow chart of a method for soldering a circuit board assembly is shown;

[0066] Figure 5b According to some embodiments of the present application, a schematic diagram of the structure of a circuit board assembly is shown. Figure 4 ;

[0067] Figure 6 According to some embodiments of the present application, a fifth structural diagram of a circuit board assembly is shown;

[0068] Figure 7 According to some embodiments of the present application, a schematic diagram of the structure of the circuit board panel in the circuit board assembly is shown. Figure 1 ;

[0069] Figure 8 According to some embodiments of the present application, a schematic diagram of the connection between a circuit board panel and an FPC in a circuit board assembly is shown;

[0070] Figure 9 According to some embodiments of the present application, a schematic diagram of the structure of a welding device is shown. Figure 2 ;

[0071] Figure 10 According to some embodiments of the present application, a schematic diagram of the structure of the circuit board assembly after the circuit board is assembled and separated is shown. Figure 1 ;

[0072] Figure 11 According to some embodiments of the present application, a schematic diagram of the structure of the circuit board panel in the circuit board assembly is shown. Figure 2 ;

[0073] Figure 12 According to some embodiments of the present application, a schematic structural diagram of an FPC in a circuit board assembly is shown;

[0074] Figure 13 According to some embodiments of the present application, a schematic diagram of the structure of the circuit board assembly after the circuit board is assembled and separated is shown. Figure 2 ;

[0075] Figure 14 According to some embodiments of the present application, a schematic diagram of the structure of a welding device is shown. Figure 3 ;

[0076] Figure 15 According to some embodiments of the present application, a schematic diagram of the structure of the center hole of the FPC is shown. Figure 1 ;

[0077] Figure 16 According to some embodiments of the present application, a schematic diagram of the structure of soldering PCBs on opposite sides of an FPC is shown. Figure 1 ;

[0078] Figure 17 According to some embodiments of the present application, a schematic diagram of processing a center hole of an FPC is shown;

[0079] Figure 18 According to some embodiments of the present application, a schematic diagram of the structure of the center hole of the FPC is shown. Figure 2 ;

[0080] Figure 19 According to some embodiments of the present application, a schematic diagram of the structure of soldering PCBs on opposite sides of an FPC is shown. Figure 2 . DETAILED DESCRIPTION

[0081] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0082] The present application provides a welding method for a circuit board assembly of a mobile terminal. The circuit board assembly includes a first circuit board and a second circuit board. The welding method of the present application can realize the welding of one first circuit board and multiple second circuit boards, or realize the welding of multiple first circuit boards and one second circuit board, or realize the welding of multiple first circuit boards and multiple second circuit boards, thereby improving the welding efficiency of the circuit board assembly.

[0083] The technical solution of this application can be applied to mobile terminals including but not limited to mobile phones, foldable phones, foldable tablets, foldable computers, wearable devices (such as smart watches), laptop computers and other devices with circuit board components. This application embodiment uses a smart watch as an example for explanation.

[0084] One of the first and second circuit boards is a printed circuit board (PCB), and the other is a flexible circuit board (FPC); or, both the first and second circuit boards are flexible circuit boards (FPC); or, both the first and second circuit boards are printed circuit boards (PCB); or, one of the first and second circuit boards is a hard board, and the other is a soft board.

[0085] This application takes the example that the first circuit board is a printed circuit board (PCB) and the second circuit board is a flexible circuit board (FPC). For the convenience of description, the printed circuit board is described as a PCB and the flexible circuit board is described as an FPC.

[0086] Typically, FPC and PCB are connected via a board to board (BTB) connector. For example, Figure 1 FIG shows one end of an FPC 10 in a smart watch (Figure 1 One end of the right side is provided with a male end 31 of a BTB connector 30, one PCB 20 is provided with a female end 32 of the BTB connector 30, and the male end 31 of the BTB connector 30 and the female end 32 of the BTB connector 30 are plugged to achieve electrical connection between the FPC 10 and the PCB 20.

[0087] However, the BTB connector 30 occupies too much space, which is not conducive to the layout of the temporal device of the smart watch and is not conducive to reducing the overall thickness of the smart watch. In order not to use the BTB connector 30 to connect the FPC 10 and the PCB 20, the FPC on board (FOB) laser welding technology is currently used to connect the FPC 10 and the PCB 20.

[0088] As shown in Figure 1 and Figure 2 , the PCB 20 of the embodiment of the present application is provided with a first welding area 21, and the second welding area 11 of the FPC 10 is welded in the first welding area 21 of the PCB 20. The first welding area 21 of the PCB 20 is provided with a plurality of pads 211, and the number of the pads 211 in the first welding area 21 is not limited in the present application, for example Figure 1 three pads 211 are provided in the first welding area 21 of the PCB 20, Figure 2 eight pads 211 are provided in the first welding area 21 of the PCB 20. Each pad 211 is electrically connected to each component described above through a metal wire (not shown in the figure). Exemplarily, the material constituting the pad 211 and the metal wire includes but is not limited to copper or copper alloy. In addition, the shape of the pad 211 is not limited, for example, the shape of the pad 211 is circular or square.

[0089] Continuing to refer to Figure 1 and Figure 2 , the FPC 10 of the embodiment of the present application includes a thermoplastic polyimide (TPI) substrate and a plurality of welding pins 111 connected to the TPI substrate. The plurality of welding pins 111 constitutes a second welding area 11 of the FPC 10, and the second welding area 11 of the FPC 10 corresponds to the first welding area 21 of the PCB 20. As shown in Figure 3 , the welding pin 111 is a hollow structure with a central hole for passing through the melted solder paste. The central hole of the welding pin 111 is attached with copper or copper alloy and the like. The hollow welding copper hole is a regular circular hole, and the shape of the central hole of the welding pin 111 is not limited in the present application, for example, it can also be a slot hole or a square hole.

[0090] It should be noted that the material of the substrate of the FPC 10 is not limited to thermoplastic polyimide (TPI), and may also be polyimide (PI) or polyester (PET).

[0091] The PCB 20 and the FPC 10 are connected by welding on a welding device. Figure 4 This is a circuit board assembly welding device in the related art. Figure 4 As shown, the circuit board assembly welding device (hereinafter referred to as welding device) includes a chassis 41, a supporting tool 42 and a pressure plate assembly 43 (for example, glass). Figure 4 As shown in the Z direction, the support fixture 42 is supported on the chassis 41 by two support columns 411. The support fixture 42 is located between the pressure plate assembly 43 and the chassis 41. That is, in the height direction, the support fixture 42 is located above the chassis 41, the pressure plate assembly 43 is located on the support fixture 42, and a laser 44 for heating the circuit board assembly is installed above the pressure plate assembly 43.

[0092] refer to Figure 3 and Figure 4 When soldering PCB20 and FPC10, first place PCB20 on the support fixture 42, so that the first soldering area 21 of PCB20 faces upward to the pressing plate assembly 43. After placing PCB20, tear off the adhesive tape on PCB20 to expose the adhesive backing 22 ( Figure 1 and Figure 2 A layer of flux can also be applied to the solder paste surface on each pad 211 within the first soldering area 21 of the PCB 20. The FPC 10 is then stacked on the PCB 20 in the height direction, i.e., the PCB 20 and the FPC 10 are stacked. The adhesive 22 adheres the FPC 10 to the PCB 20, restricting movement of the FPC 10 relative to the PCB 20.

[0093] Before soldering, it is necessary to align the soldering copper (soldering pins 111) on the FPC 10 with the soldering pads 211 on the PCB 20 accurately without deviation, that is, the center hole of the soldering copper (soldering pins 111) is aligned with the center area of ​​the soldering pad 211 (such as Figure 3 As shown in the figure), the solder can smoothly enter the center hole of the soldering copper (the center hole diameter is, for example, 0.15 mm), thereby ensuring the quality of soldering. For example, the soldering device can be provided with an identification and alignment module (not shown in the figure, such as a CCF identification and alignment module). The identification and alignment module is used to determine whether the respective soldering coppers (soldering pins 111) on the FPC 10 are accurately aligned with the respective soldering pads 211 on the PCB 20, thereby ensuring the soldering performance of the circuit board assembly.

[0094] After the FPC 10 is placed, the pressing plate assembly 43 is moved along the height direction ( Figure 4 The pressure plate assembly 43 (shown in the Z direction) is moved downward to press the FPC 10 placed on the PCB 20. When the pressure plate assembly 43 presses down on the FPC 10, the FPC 10 also presses down on the PCB 20. The laser emitted by the laser 44 heats the FPC 10, melting the solder paste on the pad 211 on the PCB 20. Under the extrusion of the FPC 10, the molten solder paste rises along the center hole of the FPC 10's soldering copper (soldering pin 111) and emerges from the side of the FPC 10 facing away from the PCB 20. After the solder solidifies, the solder connects to the soldering copper and welds the FPC 10 and PCB 20 together. Through FOB laser welding technology, the thickness of the weld between the FPC 10 and the PCB 20 is relatively thin, which can reduce the overall thickness of the circuit board assembly and reduce the space occupied by the circuit board assembly, thereby rationalizing the layout of components within the smart watch and reducing the overall thickness of the smart watch.

[0095] For example, a pressure sensor 45 is provided above the pressure plate assembly 43. The pressure sensor 45 detects the pressure applied to the circuit board assembly on the support fixture 42, thereby controlling the pressure applied to the circuit board assembly within an appropriate range before soldering. This prevents the pressure applied by the pressure plate assembly 43 from being excessive and exceeding the pressure tolerance of the circuit board assembly, thereby damaging the circuit board assembly.

[0096] In order to ensure the alignment accuracy of the welding of the flexible circuit board (FPC10) and the printed circuit board (PCB20), a welding method of one FPC10 and one PCB20 is adopted. This method has high precision, but it is impossible to weld multiple FPC10s and one PCB20 or multiple PCB20s and one FPC10 at the same time.

[0097] To this end, the present application provides a method for welding a circuit board assembly, which realizes welding multiple PCBs with FPC at one time by welding discontinuous PCBs with FPC.

[0098] Figure 5a FIG. 1 is a flow chart showing a method for soldering a circuit board assembly according to an embodiment of the present application. Figure 4 and Figure 5a As shown, the soldering method of the circuit board assembly of the embodiment of the present application includes the following steps:

[0099] S100 : placing a PCB 20 on a supporting tool 42 , wherein the PCB 20 includes more than two first welding areas 21 , and the more than two first welding areas 21 face the pressing plate assembly 43 .

[0100] refer to Figure 5b and Figure 6, PCB20 is a circuit board panel, and the circuit board panel includes a splicing structure 20b and two circuit board single boards 20a spliced ​​together. That is, the circuit board panel is a discontinuous circuit board. The present application does not limit the number N of circuit board single boards 20a in the circuit board panel, N is a positive integer, and N≥2. In some possible implementations, the circuit board panel includes other numbers of circuit board single boards 20a, such as three, four, etc. The splicing structure 20b of the embodiment of the present application connects two adjacent circuit board single boards 20a, and each circuit board single board 20a is provided with a first welding area 21. That is, Figure 5b and Figure 6 The circuit board panel is shown to include two first soldering areas 21 .

[0101] The circuit board panel can be depaneled to form individual circuit board sheets 20a (also referred to as circuit board depanels). Specifically, when manufacturing a circuit board sheet 20a (a PCB 20), a large PCB 20 (circuit board panel) is typically first formed, and then the large PCB 20 (circuit board panel) is cut into multiple smaller PCBs 20 (circuit board sheets 20a) that meet the requirements.

[0102] Figure 6 The circuit board panel also includes a process edge 20c, which connects the two splicing structures 20b together. Figure 6 A splicing structure 20b (e.g. Figure 6 The splicing structure 20b shown on the left side is connected to the process edge 20c at one end and to an adjacent circuit board 20a at the other end; Figure 6 Another splicing structure 20b (eg Figure 6 The splicing structure 20b shown on the right side is connected to a process edge 20c at one end and to an adjacent circuit board 20a at the other end. This application does not limit the number of process edges 20c. In practice, the number of process edges 20c in a circuit board panel can be set according to the requirements of the specific manufacturing process.

[0103] That is, before welding, a circuit board panel including at least two circuit board panels 20a is placed on the support fixture 42, with the first welding area 21 of each circuit board panel facing the pressure plate assembly 43. Exemplarily, each circuit board panel includes at least one first welding area 21.

[0104] For example, solder paste is printed on the pad 211 within the first welding area 21 of each circuit board 20a on the circuit board panel. After the circuit board panel is placed in the positioning area on the supporting tooling 42, a layer of flux is applied to the solder paste on the pad 211 of the circuit board 20a.

[0105] S200 : stacking an FPC 10 on a PCB 20 , wherein the FPC 10 includes two or more second soldering areas 11 , and the two or more second soldering areas 11 correspond to the two or more first soldering areas 21 in a one-to-one manner.

[0106] Continue to refer Figure 5b and Figure 6 , along the height direction, an FPC 10 is stacked on the above circuit board panel, and an FPC 10 is a continuous plate. The second welding area 11 on the FPC 10 corresponds to the first welding area 21 on the two circuit board single plates 20a. For example, Figure 5b and Figure 6 The two second soldering areas 11 of the FPC 10 are shown to be placed on the first soldering areas 21 of the two circuit boards 20a in the height direction. Similarly, the soldering copper (soldering pins 111) of each second soldering area 11 on the FPC 10 must be accurately aligned with the soldering pads 211 in the first soldering area 21 on the corresponding circuit board 20a to prevent any deviation.

[0107] For example, the thickness of the FPC 10 is between 0.07 mm and 0.5 mm, which can improve the strength of the FPC 10.

[0108] Those skilled in the art will appreciate that the number of the second welding areas 11 on the FPC 10 in the embodiment of the present application is not limited to two, and can be adjusted accordingly according to the number of the first welding areas 21 .

[0109] S300 : The pressing plate assembly 43 is pressed onto the FPC 10 to connect the two or more first welding areas 21 and the two or more second welding areas 11 by welding.

[0110] After the FPC 10 is placed on the circuit board panel, the pressure plate assembly 43 moves downward in the height direction and presses on the FPC 10. When the pressure plate assembly 43 presses down on the FPC 10, the FPC 10 also presses down on the corresponding circuit board 20a. The laser emitted by the laser 44 heats the FPC 10, melting the solder paste on the pads 211 on each circuit board 20a. Under the pressure of the FPC 10, the melted solder paste rises along the center hole of the FPC 10's soldering copper (soldering pin 111) and emerges from the side of the FPC 10 facing away from the corresponding circuit board 20a. After the solder solidifies, the solder connects to the soldering copper and welds and secures the FPC 10 to the two circuit board 20a in the circuit board panel. In other words, a weld connection is achieved between the multiple second welding areas 11 in the FPC 10 and the multiple first welding areas 21 of the multiple circuit board 20a.

[0111] For example, the circuit board assembly may be heated by the infrared laser 441 to weld and connect the two or more first welding regions 21 and the two or more second welding regions 11 .

[0112] S400: Cutting the splicing structure 20b connected to the circuit board 20a to form a circuit board assembly including the circuit board 20a.

[0113] In the above S300, a circuit board panel (including multiple circuit board single boards 20a) is welded together with an FPC 10. After the welding is completed, a panel separation operation is required. That is, the splicing structure 20b connected to the circuit board single board 20a is cut to form a circuit board assembly including the circuit board single board 20a. For example, the ultraviolet laser 442 ( Figure 14 As shown in FIG) the splicing structure 20b is cut. This is equivalent to cutting each circuit board 20a on the circuit board panel into shape, for example, referring to the following Figure 10 and Figure 13 As shown, after the circuit board panel is separated, each circuit board 20a exists independently. For example, dust cleaning is also performed after the separation operation.

[0114] After the depaneling operation, one FPC 10 is electrically connected to multiple circuit boards 20a simultaneously. That is, multiple circuit boards 20a are electrically connected to the same FPC 10. In some possible implementations, the FPC 10 can also be cut simultaneously so that each circuit board 20a is electrically connected to a separate FPC 10.

[0115] The existing circuit board assembly welding method is to place a processed PCB (circuit board) on a support fixture, then stack an FPC, and then perform FOB laser welding. In the embodiment of the present application, however, a circuit board panel is placed on a support fixture 42. The circuit board panel includes multiple circuit board single boards 20a. After the circuit board panel and an FPC 10 are welded together, the panel is separated to achieve a welded connection between an FPC 10 (including at least two welding areas) and multiple circuit board single boards 20a, thereby improving the welding efficiency of the circuit board assembly.

[0116] It should be noted that the circuit board placed on the supporting tooling 42 is not limited to PCB20, and FPC10 can also be placed on the supporting tooling 42, and PCB20 can be stacked and placed on FPC10. In addition, the embodiment of the present application is not limited to PCB20 being a circuit board panel and FPC10 being a continuous circuit board. In some possible implementations, FPC10 is a circuit board panel and PCB20 is a continuous circuit board, and the above-mentioned welding method can be used to achieve welding connections between multiple FPC10 and one PCB20. Or in some possible implementations, PCB20 is a circuit board panel and FPC10 is a circuit board panel, and each circuit board single board 20a in PCB20 corresponds one-to-one to each circuit board single board in PCB10, and the above-mentioned welding method can be used to achieve welding connections between multiple FPC10 and multiple PCB20.

[0117] In some possible embodiments, the two circuit boards of the circuit board assembly are both PCBs 20 or both FPCs 10. Accordingly, in some possible embodiments, one of the PCBs 20 is a circuit board panel, and the other PCB 20 is a continuous circuit board, and the above-mentioned welding method can be used to achieve welding connections between multiple PCBs 20 and one PCB 20. Or in some possible embodiments, both PCBs 20 are circuit board panels, and the above-mentioned welding method can be used to achieve welding connections between multiple PCBs 20 and multiple PCBs 20. Or in some possible embodiments, one of the FPCs 10 is a circuit board panel, and the other FPC 10 is a continuous circuit board, and the above-mentioned welding method can be used to achieve welding connections between multiple FPCs 10 and one FPC 10. Or in some possible embodiments, both FPCs 10 are circuit board panels, and the above-mentioned welding method can be used to achieve welding connections between multiple FPCs 10 and multiple FPCs 10.

[0118] The following description uses the example that PCB20 is a circuit board panel and FPC10 is a continuous circuit board.

[0119] Figure 1 and Figure 2 As shown, the surface of PCB 20 facing FPC 10 is covered with adhesive tape. When soldering PCB 20 and FPC 10, the adhesive tape on PCB 20 is removed to expose adhesive backing 22. When FPC 10 is placed on PCB 20, adhesive backing 22 adheres FPC 10 and PCB 20 together, preventing subsequent pulling of FPC 10 from breaking pads 211. However, the adhesive tape has a certain thickness (e.g., 0.8mm to 1.0mm), and pads 211 are, for example, 0.2mm thick. Therefore, the adhesive tape should be kept away from pads 211, which affects the density of pads 211 and thus the layout of signal lines.

[0120] For this purpose, refer to Figure 5b andFigure 6 , glue 23 is dispensed at a set distance from the edge of the first welding area 21; after being stacked on the FPC 10 on the circuit board panel, the circuit board assembly is heated and the glue between the circuit board panel and the FPC 10 is cured.

[0121] For example, glue 23 is dispensed around the perimeter of the first soldering area 21 of the circuit board 20a, replacing the adhesive tape application process. This prevents the adhesive tape from being misaligned during application. Furthermore, the glue is liquid (fluid), allowing for the placement of more solder pads 211 in the first soldering area 21 of the circuit board 20a, thereby increasing the layout density and soldering efficiency of the solder pads 211. With this increased density, the solder pads 211 can connect to more signal lines, resulting in a faster connection speed for the circuit board 20a.

[0122] After applying glue 23 to the perimeter of the first soldering area 21, the FPC 10 is placed on the circuit board 20a. The pressure of the pressure plate assembly 43 causes the liquid glue to flow. After the pressure plate assembly 43 presses the FPC 10, the thickness of the glue is the same as the thickness of the solder pad 211. Laser light emitted by the laser 44 heats the FPC 10, curing the liquid glue and bonding the FPC 10 to the PCB 20. This prevents the solder pad 211 from being broken when the FPC 10 is subsequently pulled.

[0123] The embodiment of the present application does not limit the form of glue 23 on the peripheral edge of the first welding area 21, and any glue 23 form that can achieve bonding the FPC 10 and the PCB 20 together falls within the scope of protection of the present application. Figure 5b 2 shows that the glue 23 is applied to the upper side, lower side and right side of the first welding area 21. Figure 6 The left side glue spot 23 of the first welding area 21 is shown in FIG.

[0124] The above-mentioned glue dispensing 23 process is completed on the circuit board 20a before the FPC 10 and the circuit board 20a are welded. The present application does not limit the process of glue dispensing 23. In some possible implementations, glue dispensing 23 can be performed after the FPC 10 and the circuit board 20a are welded.

[0125] For example, refer to Figure 9 , the FPC 10 is provided with a dispensing hole 101, and the dispensing hole 101 is along the height direction ( Figure 9The dispensing hole 101 is staggered with the second welding area 11. For example, the above-mentioned set distance is, for example, 0.2 mm to 10 mm. After the FPC 10 is stacked on the circuit board 20a, the dispensing hole 101 is filled with glue 23. The liquid glue will flow between the circuit board 20a and the FPC 10, heating the circuit board assembly, and solidifying the glue between the circuit board 20a and the FPC 10. This dispensing method can also bond the FPC 10 and the PCB 20 together.

[0126] Exemplarily, the heating temperature of the circuit board assembly is 150° C. to 220° C. Liquid glue can be cured within this heating temperature range.

[0127] The structure of the circuit board panel is described below with reference to the accompanying drawings.

[0128] Figure 7 A schematic diagram of the structure of a circuit board panel is shown. Figure 7 As shown, the circuit board panel includes two spaced-apart circuit board sheets 20a and two process edges 20c. The two circuit board sheets 20a are spaced-apart along the length direction ( Figure 7 A circuit board support plate 20d is provided between the two circuit board single plates 20a. The circuit board support plate 20d is used to support the FPC 10 placed on the circuit board single plate 20a to prevent the FPC 10 from collapsing. The two process edges 20c extend in the length direction and in the width direction ( Figure 7 The two circuit boards 20a and the circuit board support plate 20d are spaced apart (as shown in the X direction). The two circuit boards 20a and the circuit board support plate 20d are located between the two process edges 20c. The two sides of each circuit board 20a in the width direction are connected to the two process edges 20c via splicing structures 20b, and the two sides of the circuit board support plate 20d in the width direction are connected to the two process edges 20c via splicing structures 20b.

[0129] The two first welding areas 21 on the two circuit board sheets 20a are arranged close to the circuit board support plate 20d, so that when the FPC10 is stacked on the two circuit board sheets 20a and the circuit board support plate 20d, the two first welding areas 21 are arranged corresponding to the corresponding two second welding areas 11 on the FPC10. Figure 8 2 shows that the FPC 10 is supported by two circuit boards 20 a and a circuit board support plate 20 d , and the two second welding areas 11 on the FPC 10 correspond one-to-one to the first welding areas 21 on the circuit board 20 a . Figure 8 As shown in FIG. 2 , the first welding area 21 and the second welding area 11 overlap in a top view.

[0130] Continue to refer Figure 7 , a glue point 23 is provided between the first welding area 21 and the circuit board support plate 20d. The area of ​​the glue point 23 is close to the first welding area 21, which can improve the bonding strength between the FPC 10 and the PCB 20, and is conducive to preventing the pad 211 from being broken when the FPC 10 is pulled later.

[0131] Figure 7 As shown in FIG, each circuit board single board 20a is provided with a board separation line L, and the splicing structure 20b is connected to the board separation line L. That is, a board separation line L is provided at the connection between each circuit board single board 20a and the splicing structure 20b. For example, Figure 7 The edges of both sides of the width direction of each circuit board 20a are provided with a splitting line L. When splitting the board, the splicing structure 20b is cut along the splitting line L. Figure 10 Schematic diagram of the structure of the circuit board 20a after depaneling. The distance between the depaneling line L and the soldering area on the circuit board 20a is 0.1mm to 2mm. The distance between the solder pad 211 and the depaneling line L is increased to prevent stress cracking in the FOB after depaneling.

[0132] Continue to refer Figure 7 Each PCB board 20a also has a copper-free region 20f adjacent to the demarcation line L and a set distance (e.g., 0.2mm to 0.3mm) from the demarcation line L along the width direction. The copper-free region 20f lacks solder pads 211 and serves as the demarcation area, allowing for the removal of copper from the interior of the PCB board 20a. This ensures that the demarcation process, when cutting the spliced ​​structure 20b, does not cut into the functional traces within the PCB board 20a, achieving high-precision demarcation and avoiding the generation of scrap, significantly improving the demarcation yield.

[0133] In addition, each circuit board 20 a is provided with at least one first positioning hole 24 , and the FPC 10 is provided with second positioning holes 12 corresponding to the first positioning holes 24 . Figure 7 As shown in FIG, each circuit board 20a is provided with a first positioning hole 24. Figure 8 As shown, two second positioning holes 12 are provided on the FPC 10. Figure 8 It is shown that the first positioning hole 24 and the second positioning hole 12 overlap in a top view.

[0134] Combine Figure 9 As shown, the welding method of the embodiment of the present application also includes: the first positioning hole 24 on each circuit board 20a passes through the first positioning pin 45 on the supporting tooling 42 and is placed on the supporting tooling 42; the second positioning hole 12 of the FPC10 passes through the first positioning pin 45 on the supporting tooling 42 and is placed on the PCB20. Figure 9The location where the first locating pin 45 passes through the first locating hole 24 on the circuit board 20a, and the location where the first locating pin 45 passes through the second locating hole 12 on the FPC 10. The first locating hole 24, the second locating hole 12, and the first locating pin 45 serve as a positioning function, equivalent to setting a reference point. The two first locating pins 45 also play a role in pulling the circuit board assembly from both ends to a certain extent, preventing the positioning tooling from shifting during the FOB laser welding of the circuit board assembly, which would affect the welding performance.

[0135] Figure 9 It is also shown that the FPC 10 is provided with a wire hole 102, and the circuit board 20a is also provided with a wire hole 201.

[0136] Figure 10 FIG. 2 shows a schematic diagram of the structure of the circuit board 20a after the circuit board is split into panels. Figure 10 As shown, the first soldering area 21 of the circuit board 20a includes two rows of solder pads 211. Correspondingly, the second soldering area 11 of the FPC 10 includes two rows of solder pins 111. However, the embodiment of the present application does not limit the number of rows of solder pads 211 and solder pins 111. For example, the number of rows of solder pads 211 and solder pins 111 can also be three rows, four rows, or other rows.

[0137] like Figure 10 As shown, each row of pads 211 is arranged along the width direction ( Figure 10 The two adjacent rows of pads 211 extend along the length direction ( Figure 10 The pads 211 are arranged at intervals along the Y direction. For example, the length direction and the width direction intersect. In some possible embodiments, the length direction and the width direction are perpendicular. A row of pads 211 includes a plurality of pads 211 arranged at intervals along the width direction. Figure 10 2 shows that a row of pads 211 includes four pads 211. However, the present application does not limit the specific number of pads 211 in each row of pads 211, for example, five pads 211, six pads 211, etc.

[0138] For example, the size of each row of pads 211 along the width direction ( Figure 10(As shown in Figure A) is 40mm to 200mm, the diameter of each pad 211 is 0.3mm to 3mm; the diameter of the center hole is between 0.075mm and 0.15mm. The pads 211 aligned with the solder pins 111 in the embodiment of the present application adopt a large pad design. For example, when the width dimension of each row of pads 211 is 40mm, the diameter (equivalent diameter) of a single pad 211 is 0.3mm, and the diameter of the center hole on the FPC 10 is 0.075mm to 0.15mm. When the dimension of each row of solder pads 211 along the width direction is between 40 mm and 100 mm, the diameter of a single solder pad 211 increases by 0.1 mm for every 10 mm increase in the dimension, and the diameter of the center hole on the FPC10 remains unchanged; when the dimension of each row of solder pads 211 along the width direction is between 100 mm and 200 mm, the diameter of a single solder pad 211 increases by 0.2 mm for every 10 mm increase in the dimension, and the diameter of the center hole on the FPC10 remains unchanged.

[0139] For example, along the width direction, the gap between adjacent pads 211 ( Figure 10 The ratio of the width direction of the pad 211 to the width direction of the pad 211 is 1 / 3 to 3 / 2. The gap between adjacent pads 211 ( Figure 10 The ratio of the length direction dimension of the single pad 211 to the length direction dimension of the single pad 211 is between 1 / 3 and 3 / 2.

[0140] In the embodiment of the present application, the number of circuit board single boards 20a in the circuit board panel is not limited to Figure 5b 、 Figure 6 and Figure 7 The number of circuit board single plates 20a can also be other numbers, such as Figure 11 Another schematic diagram of the circuit board panel structure is shown. Figure 11 As shown, the circuit board panel includes five spaced-apart circuit boards 20a, with two adjacent circuit board boards 20a connected by a splicing structure 20b. Three of the circuit board boards 20a are each provided with a first welding area 21, and the other two circuit board boards 20a are each provided with a female end 32 (female connector) of a BTB connector 30. Figure 12 The FPC 10 is shown to include five parts, three of which are respectively provided with second soldering areas 11 corresponding to the first soldering areas 21 , and the other two parts are respectively provided with male ends 31 (male plugs) of the BTB connectors 30 . Figure 13 Shows the Figure 11 The structure diagram of the circuit board single board 20a after the circuit board panel is split is shown.

[0141] Similarly, when using FOB laser welding, Figure 12 The FPC10 shown is laid flat to Figure 11The circuit board panel shown in the figure uses FOB laser heating to achieve welding connections between the first welding areas 21 of multiple circuit board sheets 20a and the corresponding second welding areas 11 of the FPC 10. For example, the circuit board panels described in the above embodiments are circuit boards of equal thickness. That is, the thickness of each circuit board sheet 20a in the circuit board panel is the same. In other words, when the circuit board panel is placed on the supporting fixture, the first welding areas 21 of all circuit board sheets 20a are in the same plane. Then, Figure 4 The surface of the supporting fixture 42 supporting the circuit board panel in the welding device shown is a plane. Correspondingly, the FPC 10 is also a circuit board of uniform thickness, and the surface of the pressing plate assembly 43 pressing the FPC 10 is also a plane.

[0142] In some possible implementations, a smartwatch may utilize circuit board assemblies of varying thicknesses. For example, the circuit board 20a within the circuit board assembly may have varying thicknesses. For example, during the manufacturing process, the circuit board panelization can be fabricated using either a hole depth method or a cover-opening method to create a cavity PCB structure. This results in circuit board assemblies 20a having varying thicknesses.

[0143] The circuit board panel of the embodiment of the present application includes thick sections of circuit boards and thin sections of circuit boards of different thicknesses. Figure 14 The circuit board 20 a on the left is a thick-segment circuit board, and the circuit board 20 a on the right is a thin-segment circuit board. Figure 14 It shows that the soldering area of ​​the thick section circuit board and the soldering area of ​​the thin section circuit board are not in the same plane. Figure 9 It is shown that the soldering area of ​​the thick section circuit board and the soldering area of ​​the thin section circuit board are in the same plane.

[0144] Figure 9 and Figure 14 The welding apparatus shows a press space formed between the pressure plate assembly 43 and the support fixture 42, which is shaped like a circuit board assembly of varying thickness. This space also has varying thicknesses, and the varying thicknesses of the press space match the shape of the circuit board assembly. The circuit board assembly is placed in the press space, and the varying thicknesses of the circuit board assembly are pressed through the press space.

[0145] Exemplarily, the support fixture 42 of the welding device includes a low-end support portion 422 and a high-end support portion 421. Figure 14 B direction), the high-end support portion 421 is higher than the low-end support portion 422; the pressure plate assembly 43 includes a low-end pressure plate 431 and a high-end pressure plate 432, along the direction from the pressure plate assembly 43 toward the support tooling 42 ( Figure 14As shown in the direction A in the middle, the high-end pressing plate 432 is higher than the low-end pressing plate 431, the low-end pressing plate 431 corresponds to the low-end supporting portion 422, and the high-end pressing plate 432 corresponds to the high-end supporting portion 421 to form a pressing space of unequal thickness.

[0146] Figure 14 FIG shows a supporting fixture 42 including a low-end supporting portion 422 and a high-end supporting portion 421. Figure 14 The figure shows that the pressure plate assembly 43 includes a low-end pressure plate 431 and a high-end pressure plate 432. However, this application does not limit this. The support tooling 42 can also include other numbers of low-end support parts 422 and high-end support parts 421. The thickness of each low-end support part 422 can be the same or different, and the thickness of each high-end support part 421 can be the same or different. Similarly, the pressure plate assembly 43 can also include other numbers of low-end pressure plates 431 and high-end pressure plates 432. The thickness of each low-end pressure plate 431 can be the same or different, and the thickness of each high-end pressure plate 432 can be the same or different. The number and thickness of the low-end support parts 422 and high-end support parts 421 in the support tooling 42, as well as the number and thickness of the low-end pressure plates 431 and high-end pressure plates 432 in the pressure plate assembly 43 are adapted to the shape of the circuit board assembly to be pressed.

[0147] For example, Figure 9 The support fixture 42 shown in FIG. 4 includes a low-end support portion 422 and a high-end support portion 421. The FPC 10 is a circuit board of uniform thickness and is arranged parallel to the plane where the first welding area 21 of each circuit board 20a is located. Accordingly, the pressure plate assembly 43 can be a structural member of uniform thickness, i.e., it does not include the low-end pressure plate 431 and the high-end pressure plate 432.

[0148] Exemplarily, the thick section of the circuit board of the circuit board panel is placed on the low-end support part 422, the thin section of the circuit board of the circuit board panel is placed on the high-end support part 421, the low-end pressure plate 431 is pressed on the part of the FPC10 corresponding to the thick section of the circuit board panel, and the high-end pressure plate 432 is pressed on the part of the FPC10 corresponding to the thin section of the circuit board of the circuit board panel.

[0149] in addition, Figure 14 The FPC 10 is shown as a circuit board of uniform thickness. In some possible embodiments, the FPC 10 is a circuit board of unequal thickness. That is, the FPC 10 also includes thick sections and thin sections of circuit boards of different thicknesses. For example, Figure 9 The structure of the circuit board single board 20a shown in FIG is replaced with FPC10, Figure 9 The FPC 10 shown in the figure is replaced with a circuit board panel of equal thickness.

[0150] In some possible implementations, both the circuit board panels and the FPC 10 are circuit boards of unequal thickness. Depending on the specific shape of the circuit board assembly of unequal thickness, a support fixture 42 including a protrusion (e.g., high-end support portion 421) or a depression (e.g., low-end support portion 422) and a pressure plate assembly 43 including a protrusion (e.g., high-end pressure plate 432) or a depression (e.g., low-end pressure plate 431) can be designed to form a pressing space that aligns with the shape of the circuit board assembly of unequal thickness.

[0151] For example, Figure 4 The schematic diagram of the welding device is shown in FIG. Figure 4 As shown, the welding device includes: a chassis 41, a support fixture 42, and a pressure plate assembly 43; the support fixture 42 is supported by the chassis 41 and is located vertically between the pressure plate assembly 43 and the chassis 41; the support fixture 42 is used to place the above-mentioned circuit board assembly (for example, a circuit board assembly of uniform thickness); and a cutting device for cutting the splicing structure 20b connected to the circuit board 20a. The cutting device includes a UV laser 44, which emits a UV laser 442 to cut the splicing structure 20b connected to the circuit board 20a.

[0152] The welding device further includes: a laser 44 , which is disposed on a side of the pressing plate assembly 43 facing away from the chassis 41 . The laser emitted by the laser 44 can penetrate the pressing plate assembly 43 and irradiate the circuit board assembly on the supporting tooling 42 .

[0153] Illustratively, the aforementioned UV laser 44 is disposed on a side of the platen assembly 43 facing away from the chassis 41. The UV laser 442 emitted by the UV laser 44 can penetrate the platen assembly 43 and irradiate the circuit board assembly on the support fixture 42. Illustratively, the cutting device (e.g., UV laser 44) and the laser 44 used to heat the circuit board assembly can be the same device.

[0154] In the above embodiments, one side of the FPC 10 is soldered to the PCB 20. In some possible implementations, opposite sides of the FPC can be soldered to the PCB. Alternatively, in some possible implementations, opposite sides of the PCB can be soldered to the FPC. Alternatively, in some possible implementations, one side of the FPC is soldered to the FPC, and the other side is soldered to the PCB. Alternatively, in some possible implementations, one side of the PCB is soldered to the FPC, and the other side is soldered to the FPC.

[0155] The embodiment of the present application is described by taking the example of soldering PCBs on opposite sides of the FPC.

[0156] Please refer to Figure 15 , Figure 15 FIG. 1 shows a schematic structural diagram of the center hole of the first welding area 111 of the FPC 10.Figure 15 As shown, the first welding area 111 of the FPC 10 includes welding pins, and the welding pins include Figure 15 The central hole extends in the Z direction, and the central hole includes a first section 111a, a second section 111b and a third section 111c that are sequentially connected along the stacking direction. The aperture of the first section 111a is ( Figure 15 R1 in the figure) is larger than the aperture of the second section 111b ( Figure 15 R2 in the figure), the aperture of the third section 111c ( Figure 15 The diameter of the aperture of the first section 111a is equal to the diameter of the aperture of the third section 111c, which facilitates the processing and forming of the center hole.

[0157] That is, the center hole of the first welding area 111 of the FPC 10 of the embodiment of the present application is a double-sided large hole (the first section 111a and the third section 111c are the holes with the larger aperture in the center hole), and a small hole in the middle (the second section 111b is the hole with the smaller aperture in the center hole). For example, the aperture of the small hole in the middle (the second section 111b of the center hole) is smaller than the diameter of the solder particles, for example, smaller than the diameter of two solder particles, so that the tin printed on the FPC 10 does not penetrate to the other side. If the center hole is a via with a constant diameter along the stacking direction, the tin printed on one side of the FPC 10 will penetrate to the other side of the FPC 10, causing the other side of the FPC 10 to be raised and unable to be soldered to the PCB 20.

[0158] In the embodiment of this application, reference Figure 16 , the stacking direction of FPC10 ( Figure 16 The first PCB 202 and the second PCB 203 are welded on opposite sides of the FPC 10 (shown in the Z direction), the welding pad of the first PCB 202 is welded to the first section 111a of the welding pin of the FPC 10, and the welding pad of the second PCB 203 is welded to the third section 111c of the welding pin of the FPC 10.

[0159] Specifically, after solder is placed in the first section 111a on one side of the FPC 10, the solder does not flow down from the second section 111b to the third section 111c. After the FPC 10 and the first PCB 202 on that side are soldered, there is no solder on the other side of the FPC 10, and the height of the other side of the FPC 10 does not increase. Therefore, if the FPC 10 is flipped 180° and solder is placed in the third section 111c on the other side of the FPC 10, the second PCB 203 can be soldered to the FPC 10 normally. For example, the first PCB 202 and the second PCB 203 overlap in the stacking direction, resulting in a compact circuit board assembly.

[0160] refer toFigure 15 The height of the first section 111a of the central hole is H1, the height of the second section 111b is H2, and the height of the third section 111c is H3. For example, H1 / H2 ≥ 1.2, H3 / H2 ≥ 1.2, and H2 ≥ 0.03 mm. This arrangement prevents the solder in the second section 111b from sinking into the first section 111a or the third section 111c. For example, the solder particles have a diameter of 0.01 mm.

[0161] Please refer to Figure 17 , Figure 17 Shown Figure 15 The processing process of the center hole of the first welding area 111 is shown. Figure 17 As shown in (a), first drill the first section 111a and the second section 111b of the center hole on one side of the FPC 10; then, turn the FPC 10 180 degrees. Figure 17 As shown in (b), the third section 111c of the center hole is drilled on the other side of the FPC 10 to realize large holes on both sides.

[0162] In some possible implementations, reference Figure 18 The first welding area 111 of the FPC 10 includes a first welding pin (eg Figure 18 The left solder pin) and the second solder pin (e.g. Figure 18 The first welding pin and the second welding pin respectively include a center hole extending along the stacking direction, and the center hole of the first welding pin includes a center hole extending along the stacking direction ( Figure 18 The first section 111a and the second section 111b are connected (shown in the Z direction), and the aperture of the first section 111a of the first welding pin is ( Figure 18 R1 in the figure) is larger than the aperture of the second section 111b ( Figure 18 The center hole of the second welding pin includes a first section 111a and a second section 111b connected along the stacking direction, and the aperture of the first section 111a of the second welding pin is ( Figure 18 R1 in the figure) is larger than the aperture of the second section 111b ( Figure 18 , where R1 is the product of the product of the invention and R2 is the product of the product of the invention. For example, 1.2≤R1 / R2≤5.

[0163] That is, the center hole of the first welding pin of the first welding area 111 of FPC10 is a large hole on one side (the first section 111a of the center hole) and a small hole on the other side (the second section 111b of the center hole); the center hole of the second welding pin of the first welding area 111 of FPC10 is a large hole on one side (the first section 111a of the center hole) and a small hole on the other side (the second section 111b of the center hole), the first section 111a of the first welding pin and the first section 111a of the second welding pin are located on opposite sides of FPC10, and the second section 111b of the first welding pin and the second section 111b of the second welding pin are located on opposite sides of FPC10.

[0164] For example, the aperture of the small hole (the second section 111b of the central hole) is smaller than the diameter of the solder particles, for example, smaller than the diameters of two solder particles, so that the tin printed on the FPC 10 does not penetrate to the other side. Figure 19 The first PCB 202 and the second PCB 203 are welded on opposite sides of the stacking direction of the FPC 10, respectively. The soldering pad of the first PCB 202 is welded to the first section 111a of the first welding pin of the FPC 10, and the soldering pad of the second PCB 203 is welded to the first section 111a of the second welding pin of the FPC 10.

[0165] Specifically, after solder is placed in the first section 111a on one side of the first soldering pin on the FPC 10, the solder will not flow down from the second section 111b to the other side of the FPC 10. After the first soldering pin of the FPC 10 is soldered to the first PCB 202 on that side, no solder will remain on the other side of the FPC 10, and the height of the other side of the FPC 10 will not increase. Therefore, if the FPC 10 is flipped 180 degrees and solder is placed in the first section 111a of the second soldering pin on the other side of the FPC 10, the second PCB 203 can be soldered to the FPC 10 normally. This allows the FPC 10 to simultaneously solder PCBs 20 that are misaligned on both sides, that is, the first PCB 202 and the second PCB 203 are offset in the stacking direction.

[0166] refer to Figure 18 The height of the first section 111a of the central hole is H1, and the height of the second section 111b is H2. For example, H1 ≥ 0.03mm, and H2 ≥ 0.03mm. This arrangement prevents the solder in the second section 111b from sinking into the first section 111a. For example, the solder particles have a diameter of 0.01mm.

[0167] For example, Figures 15 to 19 The structure of the FPC 10 shown in the above embodiment is similar to that of the Figures 5b to 13 The structure of FPC10 is the same as that of Figures 15 to 19 The structure of the PCB 20 shown above Figures 5b to 13 The structure of PCB20 is the same.

[0168] In summary, the welding method of the embodiments of the present application can realize simultaneous welding of one circuit board and multiple circuit boards, or simultaneous welding of several circuit boards and multiple circuit boards, thereby improving welding efficiency and reducing cost; can improve connection efficiency and realize simultaneous connection of multiple interfaces at both ends of the FPC; can also realize simultaneous welding of PCBs and FPCs of multiple thicknesses, FPCs and FPCs, PCBs and PCBs; can reduce the replacement of BTB connector connection and reduce the connection thickness.

Claims

1. A method for soldering a circuit board assembly, characterized in that: The welding method is applied to a welding device including a chassis, a supporting tool and a pressure plate assembly, wherein the supporting tool is supported by the chassis and is located between the pressure plate assembly and the chassis; the welding method comprises: placing a first circuit board on the supporting fixture, wherein the first circuit board comprises two or more first welding areas, and the two or more first welding areas face the pressing plate assembly; Laying a second circuit board on the first circuit board, wherein the second circuit board includes two or more second welding areas, and the two or more second welding areas correspond to the two or more first welding areas one by one; The pressing plate assembly is pressed on the second circuit board to weld the two or more first welding areas and the two or more second welding areas together; wherein, At least one of the first circuit board and the second circuit board is a circuit board panel, the circuit board panel including a splicing structure and N circuit board sheets spliced ​​together, N being a positive integer and N≥2, the splicing structure connecting two adjacent circuit board sheets, and each circuit board sheet being provided with a welding area; Cutting the splicing structure connected to the circuit board to form a circuit board assembly including the circuit board; The circuit board assembly has different thicknesses, and a pressing space of different thicknesses is formed between the pressure plate assembly and the supporting tooling of the welding device, and the pressing space of different thicknesses is similar in shape to the circuit board assembly of different thicknesses; the welding method includes: placing the circuit board assembly in the pressing space of different thicknesses, and pressing the circuit board assembly through the pressing space of different thicknesses.

2. The welding method according to claim 1, wherein: The first circuit board is a circuit board panel, and the second circuit board is a continuous circuit board; or, the second circuit board is a circuit board panel, and the first circuit board is a continuous circuit board; or, the first circuit board is a circuit board panel, and the second circuit board is a circuit board panel, and each circuit board single board in the first circuit board corresponds one-to-one to each circuit board single board in the second circuit board.

3. The welding method according to claim 1, wherein: Glue is dispensed at a set distance from the edge of the first welding area; after the second circuit board is stacked on the first circuit board, the circuit board assembly is heated to solidify the glue between the first circuit board and the second circuit board.

4. The welding method according to claim 3, wherein: Apply glue to the peripheral edge of the first welding area.

5. The welding method according to claim 1, wherein: A glue dispensing hole is provided on the second circuit board, which passes through the second circuit board and is set at a distance from the edge of the second welding area; after the second circuit board is stacked on the first circuit board, glue is filled in the glue dispensing hole, the circuit board assembly is heated, and the glue between the first circuit board and the second circuit board is cured.

6. The welding method according to any one of claims 3 to 5, characterized in that: The set distance is 0.2 mm to 10 mm.

7. The welding method according to claim 3 or 5, characterized in that: The heating temperature of the circuit board assembly is 150° C. to 220° C.

8. The welding method according to any one of claims 1 to 5, characterized in that: One of the first welding area and the second welding area includes at least two rows of welding pads, and the other includes welding pins welded to the at least two rows of welding pads; Each row of pads extends along a first direction, two adjacent rows of pads are spaced apart along a second direction, the first direction and the second direction intersect, and one row of pads includes a plurality of pads spaced apart along the first direction; The soldering pin includes a central hole extending along a third direction.

9. The welding method according to claim 8, wherein: The size of each row of pads along the first direction is between 40 mm and 200 mm, the diameter of each pad is between 0.3 mm and 3 mm; and the diameter of the center hole is between 0.075 mm and 0.15 mm.

10. The welding method according to claim 8, wherein: Along the first direction, the ratio of the gap between adjacent pads to the size of a single pad in the first direction is 1 / 3 to 3 / 2, and along the second direction, the ratio of the gap between adjacent pads to the size of a single pad in the second direction is 1 / 3 to 3 / 2.

11. The welding method according to any one of claims 1 to 5, characterized in that: The circuit board is provided with a splitting line, the splicing structure is connected to the splitting line, and the distance between the splitting line and the welding area on the circuit board is 0.1 mm to 2 mm.

12. The welding method according to any one of claims 1 to 5, characterized in that: The first circuit board is provided with one or more first positioning holes, and the second circuit board is provided with second positioning holes corresponding to the first positioning holes; The first positioning hole of the first circuit board passes through the first positioning pin on the supporting fixture and is then placed on the supporting fixture; The second positioning hole of the second circuit board passes through the first positioning pin on the supporting fixture and is then placed on the first circuit board.

13. The welding method according to claim 1, wherein: The first circuit board and / or the second circuit board are circuit boards of unequal thickness.

14. The welding method according to claim 13, wherein: The first circuit board includes at least a thick section circuit board and a thin section circuit board of different thicknesses; the supporting fixture includes a low-end supporting portion and a high-end supporting portion, and along the direction from the supporting fixture toward the pressure plate assembly, the high-end supporting portion is higher than the low-end supporting portion; the pressure plate assembly includes a low-end pressure plate and a high-end pressure plate, and along the direction from the pressure plate assembly toward the supporting fixture, the high-end pressure plate is higher than the low-end pressure plate, the low-end pressure plate corresponds to the low-end supporting portion, and the high-end pressure plate corresponds to the high-end supporting portion; The thick section of the first circuit board is placed on the low-end support portion, the thin section of the first circuit board is placed on the high-end support portion, the low-end pressure plate is pressed on the portion of the second circuit board corresponding to the thick section of the first circuit board, and the high-end pressure plate is pressed on the portion of the second circuit board corresponding to the thin section of the first circuit board.

15. The welding method according to claim 14, wherein: The welding area of ​​the thick section circuit board and the welding area of ​​the thin section circuit board are not in the same plane.

16. The welding method according to any one of claims 1 to 5 and 13 to 15, characterized in that: One of the first circuit board and the second circuit board is a printed circuit board, and the other is a flexible circuit board; or both the first circuit board and the second circuit board are flexible circuit boards; or both the first circuit board and the second circuit board are printed circuit boards.

17. The welding method according to claim 16, wherein: The thickness of the flexible circuit board is between 0.07 mm and 0.5 mm.

18. The welding method according to any one of claims 1 to 5 and 13 to 15, characterized in that: The circuit board assembly is heated by infrared laser to weld the two or more first welding areas and the two or more second welding areas together; and the splicing structure is cut by ultraviolet laser.

19. The welding method according to any one of claims 1 to 5 and 13 to 15, characterized in that: The first welding area includes a welding pin, the welding pin includes a central hole extending along the stacking direction, the central hole includes: a first section, a second section, and a third section connected in sequence along the stacking direction, the aperture of the first section is larger than the aperture of the second section, and the aperture of the third section is larger than the aperture of the second section; The second circuit boards are welded on opposite sides of the stacking direction of the first circuit board, and the second welding area of ​​the second circuit board includes welding pads welded to the welding pins, wherein the welding pads of one of the second circuit boards are welded to the first section of the welding pin, and the welding pads of the other second circuit board are welded to the third section of the welding pin.

20. The welding method according to claim 19, wherein: The two second circuit boards overlap in the stacking direction.

21. The welding method according to any one of claims 1 to 5 and 13 to 15, characterized in that: The first welding area includes a first welding pin and a second welding pin, the first welding pin and the second welding pin respectively including a central hole extending in the stacking direction, the central hole of the first welding pin including a first section and a second section connected in the stacking direction, the aperture of the first section of the first welding pin being larger than the aperture of the second section; the central hole of the second welding pin including a first section and a second section connected in the stacking direction, the aperture of the first section of the second welding pin being larger than the aperture of the second section; The second circuit boards are welded to opposite sides of the stacking direction of the first circuit board, and the second welding area of ​​the second circuit board includes welding pads welded to the welding pins, wherein the welding pads of one of the second circuit boards are welded to the first section of the first welding pin, and the welding pads of the other second circuit board are welded to the first section of the welding pin.

22. The welding method according to claim 21, wherein: The two second circuit boards are staggered in the stacking direction.

23. A welding device, characterized in that: include: chassis, support fixtures, and platen assemblies; The supporting fixture is supported by the chassis, and along the height direction, the supporting fixture is located between the pressure plate assembly and the chassis; The supporting fixture is used to place a circuit board assembly, the circuit board assembly including a first circuit board and a second circuit board stacked on the first circuit board, the first circuit board including two or more first welding areas, the two or more first welding areas facing the pressure plate assembly, and the second circuit board including two or more second welding areas, the two or more second welding areas corresponding to the two or more first welding areas one-to-one; The pressing plate assembly is used to be pressed on the second circuit board; At least one of the first circuit board and the second circuit board is a circuit board panel, the circuit board panel comprising a splicing structure and N circuit board sheets spliced ​​together, where N is a positive integer and N ≥ 2, the splicing structure connects two adjacent circuit board sheets, and each circuit board sheet is provided with a welding area; A cutting device for cutting the spliced ​​structure connected to the circuit board; The circuit board assemblies are of unequal thickness, and a unequal thickness pressing space is formed between the pressing plate assembly and the supporting tooling, and the unequal thickness pressing space is shaped like the circuit board assemblies of unequal thickness; the unequal thickness pressing space is used to place the circuit board assemblies of unequal thickness and press the circuit board assemblies of unequal thickness.

24. The welding device according to claim 23, wherein: Also includes: A laser is arranged on a side of the pressing plate assembly facing away from the chassis, and the laser emitted by the laser can penetrate the pressing plate assembly and irradiate the circuit board assembly on the supporting tooling.

25. The welding device according to claim 23, wherein The cutting device includes an ultraviolet laser, and the ultraviolet laser emitted by the ultraviolet laser cuts the splicing structure connected to the circuit board.

26. The welding device according to claim 25, wherein The ultraviolet laser is arranged on a side of the pressing plate assembly facing away from the chassis.

27. The welding device according to claim 23, wherein: The supporting tooling includes a low-end supporting portion and a high-end supporting portion, and along the direction from the supporting tooling toward the pressure plate assembly, the high-end supporting portion is higher than the low-end supporting portion; The pressure plate assembly includes a low-end pressure plate and a high-end pressure plate. Along the direction from the pressure plate assembly toward the supporting tooling, the high-end pressure plate is higher than the low-end pressure plate. The low-end pressure plate corresponds to the low-end support part, and the high-end pressure plate corresponds to the high-end support part to form the unequal thickness pressing space.

28. The welding device according to claim 27, wherein: The first circuit board comprises at least a thick section circuit board and a thin section circuit board of different thicknesses; The low-end supporting portion is used to place a thick section of the first circuit board, and the high-end supporting portion is used to place a thin section of the first circuit board; The low-end pressing plate is used to press the portion of the second circuit board corresponding to the thick section of the first circuit board, and the high-end pressing plate is used to press the portion of the second circuit board corresponding to the thin section of the first circuit board.

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