Welding method and welding device for SMT and THT ultra-dense interval mixed loading

Abstract

The invention discloses a welding method for SMT (Surface Mount Technology) and THT (Total Heat Transfer) super-dense pitch mixed installation, which is applied to a PCB (Printed Circuit Board) welding process for SMT and THT super-dense pitch mixed installation, and is characterized by comprising the following steps which are executed in sequence: printing soldering paste of a to-be-welded surface-mounted element on a PCB; the surface-mounted element is arranged at the soldering paste of the PCB; carrying out reflow soldering on the PCB to realize welding of the surface-mounted element and the PCB; a through hole element to be welded is inserted into a hole formed in the PCB in advance; and fixing the PCB on a welding device, and enabling the welding device to realize the welding of the through hole element and the PCB through a crest welder.

Description

Technical Field

[0001] The present invention belongs to the technical field of SMT and THT mixed soldering, and particularly relates to a soldering method and a soldering device for ultra-fine pitch mixed mounting of SMT and THT. Background Art

[0002] With the development of electronic products towards miniaturization, lightweight, and high performance, the mixed mounting technology of PCBs faces increasingly high requirements, mainly reflected in high density and high reliability. Specifically, the size of components is reduced and the number increases, resulting in a significant increase in the wiring density and assembly density of PCBs. At the same time, with the wide application of electronic products in fields such as automotive, medical, and aerospace, higher requirements are put forward for the reliability of PCBs. Soldering is a key link in PCB assembly, and the soldering quality of PCBs directly determines the reliability and lifespan of products. In addition, the current mainstream design of SMT (Surface Mount Technology) and THT (Through Hole Technology) mixed mounting design combined with the requirements of PCB wiring density requires more precise soldering requirements for SMT and THT in the soldering process.

[0003] However, in the current existing soldering processes, due to limitations in carriers and equipment, etc., there are certain limitations in the soldering methods for different pad pitches, especially in the soldering of ultra-fine pitch PCBs with SMT / THT pad pitches less than 1.5 mm. Specifically, for SMT / THT pad pitches greater than or equal to ≥ 3 mm, the WS combined with soldering device soldering technology is adopted. When the SMT / THT pad pitch is greater than 1.5 mm, selective soldering technology can be adopted. Using this technology also requires that there be a soldering nozzle operation space of more than 6 mm in the THT soldering area. If the SMT / THT pad pitch is less than 1.5 mm for ultra-fine pitch, then manual soldering is used, and it is difficult to guarantee high reliability in manual soldering. Summary of the Invention

[0004] The present invention innovatively proposes a soldering process for ultra-fine pitch mixed mounting of SMT and THT, innovatively designs a device for this soldering process, and designs the performance of the device to achieve a high-precision protection and isolation mechanism for surface-mounted components in ultra-fine pitch mixed mounting of SMT and THT, fully exposing the soldering points of through-hole components, effectively solving the thermal damage and shadow effect during ultra-fine pitch mixed soldering, significantly improving the soldering yield and component reliability, and can be widely applied to high-density electronic manufacturing fields (such as 5G communication equipment, automotive electronics, etc.).

[0005] To solve the above problems, the first aspect of the present invention provides a soldering method for ultra-fine pitch mixed mounting of SMT and THT, which is applied to the PCB soldering process of ultra-fine pitch mixed mounting of SMT and THT, and includes the following steps executed in sequence: Print the solder paste of the mounting component to be welded onto the PCB board; Place the mounting component at the solder paste on the PCB board; Perform reflow soldering on the PCB board to achieve the welding of the mounting component and the PCB board; Insert the through-hole component to be welded into the holes pre-set on the PCB board; Fix the PCB board on the welding device, and use a wave soldering machine on the welding device to achieve the welding of the through-hole component and the PCB board.

[0006] Preferably, the welding device includes a frame and a chassis. A fixing area for fixing the PCB board is provided on the first end face of the frame. The chassis is provided with a plurality of protection grooves and a plurality of welding holes. The protection grooves are used to cover the surface-mounted components of the PCB board. The size and position of the protection grooves are adapted to the position and size of the surface-mounted component area of the PCB board. The welding holes provide space for the through-hole components of the PCB board to pass through and be welded. The size of the welding holes is adapted to the size of the pads of the through-holes. The first end face is provided with a through-hole having a space for accommodating a plurality of the protection grooves and the plurality of welding holes. The chassis is fixed to the outer edge of the through-hole by a first fixing member.

[0007] Preferably, the welding device further includes at least one support bar, and the support bar is fixed to the edge of the first end face by at least one second fixing member.

[0008] Preferably, the first fixing member and the second fixing member are both made of stainless steel screws.

[0009] Preferably, the first end face is provided with a first groove and a second groove. The first groove is provided outside the edge of the fixing area, and the second groove is provided outside the edge of the through-hole.

[0010] Preferably, the frame is provided with at least 2 locking mechanisms for fixing the PCB board. The locking mechanism includes a fixing shaft, an elastic member and a limit buckle; a limit portion is provided at the first end of the fixing shaft. The limit buckle and the elastic member are sleeved on the fixing shaft, and the elastic member is located between the limit portion and the limit buckle. The fixing shaft is fixedly connected to the outside of the edge of the fixing area.

[0011] Preferably, the fixing shaft is made of stainless steel material, the elastic member is a stainless steel screw, and the limit buckle is made of a glass fiber and resin composite.

[0012] In a second aspect of the present invention, a soldering device for SMT and THT ultra-fine pitch mixed soldering is provided, including a frame and a chassis. The chassis is provided with a number of protection grooves for protecting surface-mounted components and a number of soldering holes to provide soldering space for through-hole components. The soldering method for SMT and THT ultra-fine pitch mixed soldering according to any one of the preceding claims is used to solder a PCB with SMT and THT ultra-fine pitch mixed soldering. The protection groove includes two protection walls and a mask. The protection walls are fixed on the edge of the chassis. The protection walls are located on the vertical plane at the connection of the pads of the surface-mounted components and the pads of the through-hole components of the fixed PCB board and extend towards the through-hole space opened by the frame. The tops of two adjacent protection walls are connected by the mask. The height of the protection wall is adapted to the height of the protected surface-mounted components. The height of the protection wall is 0.5-6 mm, and the thickness of the protection wall is 0.3 mm. The frame is made of composite stone, and the chassis is made of titanium alloy.

[0013] Due to the above technical solutions adopted in the present invention, compared with the prior art, it has the following advantages and positive effects: The embodiment of the present invention proposes an automated soldering method applicable to SMT and THT ultra-fine pitch mixed soldering. Through the step-by-step process of "SMT first, then reflow soldering, and finally THT wave soldering", the soldering process of ultra-fine pitch mixed soldering is innovatively realized. By optimizing the soldering process flow and parameter control, this method effectively solves the limitations of traditional soldering technology in high-density mixed soldering, significantly improves the soldering quality and production efficiency. Step-by-step soldering reduces the equipment debugging time and manufacturing cost, and at the same time avoids thermal damage (such as desoldering and failure) to the surface-mounted components in the PCB with SMT and THT ultra-fine pitch mixed soldering caused by the two soldering processes.

[0014] In the embodiment of the present invention, the soldering device is provided with protection grooves, which cover the area of the surface-mounted components, block the splash and overflow of solder, and avoid short circuits; it provides an effective soldering tool for automated soldering: the soldering holes accurately expose the through-hole pads, ensure that the solder accurately covers the target position, and improve the soldering accuracy. The protection walls are made of titanium alloy and the height of the protection walls is set to: 0.5-6 mm to adapt to various types of surface-mounted components of the protected PCB board. The thickness of the protection walls is set to 0.3 mm. The above settings reduce the situation of the protection grooves occupying space, reduce the shadow effect generated during the soldering process, and thus improve the soldering yield.

[0015] The soldering device in the embodiment of the present invention is equipped with detachable support bars, locking mechanisms, grooves and other components, which can flexibly adapt to different sizes of PCB boards and component layouts, and meet the diverse soldering process requirements of SMT (Surface Mount Technology) and THT (Through-Hole Technology) ultra-fine pitch mixed soldering. Description of the Drawings

[0016] The following further elaborates on the specific implementation manners of the present invention in conjunction with the accompanying drawings, where: Figure 1 It is a schematic flowchart of the soldering method for SMT and THT ultra-dense pitch mixed mounting of the present invention; Figure 2 It is a structural diagram of the frame in the soldering device of the soldering method for SMT and THT ultra-dense pitch mixed mounting of the present invention; Figure 3 It is a schematic diagram of the positions of the PCB board and the chassis for SMT and THT ultra-dense pitch mixed mounting of the present invention; Figure 4 It is a schematic diagram of the positions of the PCB board and the frame for SMT and THT ultra-dense pitch mixed mounting of the present invention; Figure 5 It is a schematic diagram of the installation of the frame and the chassis in the soldering device of the soldering method for SMT and THT ultra-dense pitch mixed mounting of the present invention; Figure 6 It is a schematic diagram of the soldering effect and the through-tin rate effect of the PCB for SMT and THT ultra-dense pitch mixed mounting of the present invention; Explanation of the reference numerals in the drawings: 1: Frame; 101: Locking mechanism; 102: Support bar; 103: First fixing member; 104: First groove; 105: Second groove; 106: Second fixing member; 107: Fixing area; 2: Chassis; 201: Protection groove; 20101: Protection wall; 202: Soldering hole. Specific implementation manners

[0017] The following further elaborates on the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description and the claims, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0018] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the accompanying drawings). If this specific posture changes, then the directional indications will also change accordingly.

[0019] Embodiment 1 For ease of understanding, the following describes the specific process of the embodiment of the present invention in detail. Please refer to Figure 1 , a soldering method for SMT and THT ultra-dense pitch mixed mounting, applied to the PCB soldering process of SMT and THT ultra-dense pitch mixed mounting, including the following steps executed in sequence: S100: Print the solder paste of the mounting components to be soldered onto the PCB board; S200: The surface mount component is disposed at the solder paste on the PCB board; S300: The PCB board is subjected to reflow soldering to realize the soldering of the surface mount component and the PCB board; S400: Insert the through-hole component to be soldered into the holes preset on the PCB board; S500: Fix the PCB board on the soldering device, and the soldering device realizes the soldering of the through-hole component and the PCB board through a wave soldering machine.

[0020] Please refer to Figure 2 and Figure 5 , preferably, the soldering device includes a frame 1 and a chassis 2. A fixing area 107 for fixing the PCB board is provided on the first end face of the frame 1. The chassis 2 is provided with a plurality of protection grooves 201 and a plurality of soldering holes 202. The protection grooves 201 are used to cover the surface mount components on the PCB board. The size and position of the protection grooves 201 are adapted to the position and size of the surface mount component area on the PCB board. The soldering holes 202 provide a space for the through-hole components on the PCB board to pass through and be soldered. The size of the soldering holes 202 is adapted to the size of the pads of the through-holes. The first end face is provided with a through-hole having a space for accommodating a plurality of protection grooves 201 and a plurality of soldering holes 202. The chassis 2 is fixed to the outer edge of the through-hole and fixed by a first fixing member 103.

[0021] In step S500, the PCB board is fixed on the soldering device. The soldering device is provided with a frame 1 and a chassis 2. The chassis 2 is fixed on the outer edge of the through-hole provided in the frame 1, so that the protection grooves 201 and the soldering holes 202 on the chassis 2 are clamped in the space of the through-hole, and the PCB board is fixed in the fixing area 107. After the PCB board is fixed to the soldering device, the following effects are generated: The chassis 2 contacts the exposed surface of the pins of the through-hole components on the PCB board. The protection grooves 201 and the PCB board form a sealed space. The through-hole components on the PCB board pass through the soldering holes 202 to expose the pins and the through-hole pads in the space on the second end face of the frame 1. The soldering work of the wave soldering machine is also completed in the space on the second end face.

[0022] Continue to refer to Figure 2 and Figure 4 , preferably, the soldering device further includes at least one support bar 102, and the support bar 102 is fixed to the edge of the first end face by at least one second fixing member 106.

[0023] The support bar 102 can enhance the structural strength and stability of the carrier, prevent deformation, and reduce the sputtering or overflow of solder to non-soldering areas during the soldering process.

[0024] Preferably, both the first fixing member 103 and the second fixing member 106 are made of stainless steel screws.

[0025] Refer to Figure 5, preferably, the first end face is provided with a first groove 104 and a second groove 105. The first groove 104 is arranged outside the edge of the fixed area 107, and the second groove 105 is arranged outside the edge of the through hole. The stainless steel screw has corrosion resistance and high temperature resistance, which helps to extend the service life of the carrier.

[0026] Refer to Figure 2 , preferably, the frame 1 is provided with at least two locking mechanisms 101 for fixing the PCB board. The locking mechanism 101 includes a fixed shaft, an elastic member and a limit buckle; a limit portion is provided at the first end of the fixed shaft. The limit buckle and the elastic member are sleeved on the fixed shaft, and the elastic member is located between the limit portion and the limit buckle. The fixed shaft is fixedly connected to the outside of the edge of the fixed area 107.

[0027] The operating steps for fixing the PCB board to the welding device are as follows: First, adjust the position of the limit buckle: Rotate the limit buckle on the locking mechanism 101 to a spatial position where there is no interference with the fixed area 107 to ensure that it does not obstruct the placement of the PCB board. Second, place the PCB board: Place the PCB board in the fixed area 107, make the welding surface of the through-hole components of the PCB board contact the first end face, and ensure that the welding area of the through-hole components passes through the through hole provided in the first end face. Third, lock the PCB board: Rotate the limit buckle so that it is located above the PCB board. If the limit buckle cannot be smoothly clamped on the PCB board, apply a force towards the limit portion to lift the limit buckle and complete the clamping. After the clamping is completed, remove the applied force, and the PCB board is firmly fixed. In this embodiment, there are 6 locking mechanisms 101, which are evenly arranged on a pair of parallel outer edges of the fixed area 107. Of course, the number of the locking mechanisms 101 can be other numbers greater than 1, which is not limited in this embodiment.

[0028] Preferably, the fixed shaft is made of stainless steel material, the elastic member is a stainless steel screw, and the limit buckle is made of a glass fiber and resin composite. The stainless steel screw, the glass fiber and resin composite have corrosion resistance and high temperature resistance, which helps to extend the service life of the carrier.

[0029] Embodiment 2 A soldering device for SMT and THT ultra-fine pitch mixed mounting soldering, comprising a frame 1 and a chassis 2, and the chassis 2 is provided with a number of protection grooves 201 for protecting surface-mounted components and a number of soldering holes 202 for providing a soldering space for through-hole components. The soldering method for SMT and THT ultra-fine pitch mixed mounting in any one of the above is used to solder the PCB of SMT and THT ultra-fine pitch mixed mounting. The protection groove 201 includes two protection walls 20101 and a mask. The protection walls 20101 are fixed on the edge of the chassis 2. The protection walls 20101 are located on the vertical plane at the connection of the surface-mounted component pads and the through-hole component pads of the fixed PCB board and extend towards the through-hole space opened by the frame 1. The tops of two adjacent protection walls 20101 are connected by a mask. The height of the protection wall 20101 is adapted to the height of the protected surface-mounted components. The height of the protection wall 20101 is 0.5 - 6 mm, and the thickness of the protection wall 20101 is 0.3 mm. The frame 1 is made of composite stone, and the chassis 2 is made of titanium alloy.

[0030] The height of the protection wall 20101 (0.5 - 6 mm) is adapted to protect various surface-mounted components. The thickness of the protection wall 20101 is set to (0.3 mm), which reduces the space occupied by the protection groove 201, avoids interfering with the through-hole soldering and the shadow effect generated during the soldering process, and thus improves the soldering yield.

[0031] The working process of the present invention will be further described below: Design a soldering device for a soldering method for SMT and THT ultra-fine pitch mixed mounting: Chassis design: The chassis 2 is provided with a number of protection grooves 201 for protecting the mounted components on the PCB board. The protection groove 201 includes two protection walls 20101 and a mask. The protection wall 20101 is located on the vertical plane at the connection of the solder pads of the surface-mounted components and the via-hole components of the fixed PCB board and extends towards the through-hole space opened by the frame. When the adjacent protection walls 20101 are connected to the mask, a protection groove is formed, and when there is no mask, a soldering hole is formed to provide a soldering space for the pins and solder pads of the via-hole components. Further, the height of the protection wall 20101 is set to 0.5 - 6 mm to adapt to the protection of various surface-mounted components. The thickness of the protection wall 20101 is set to 0.3 mm, which reduces the space occupied by the protection groove 201, avoids interfering with the via-hole soldering and the shadow effect generated during the soldering process, and thus improves the soldering yield. Frame design: Customize a fixed area 107 for the PCB board in advance to ensure the relative stability of the PCB board during the soldering process. The chassis 2 provides a component for protecting the mounted components and soldering the via-hole components. Stable protection and soldering space are achieved through the mutual cooperation of the PCB board, the frame 1, and the chassis 2. Considering the convenience of installation and unloading, the frame 1 and the support bars 102 are connected by fixing parts (a number of first fixing parts 103), and the PCB board is fixed using a locking mechanism, which can meet the fixing of PCB boards of different heights. Selection of parts materials: Considering the high temperature and corrosiveness during the soldering process, the first fixing parts 103, the second fixing parts 106, and the elastic parts of the locking mechanism in the design process are all made of stainless steel screws. The fixed shaft of the locking mechanism is made of stainless steel material, and the limit buckle of the locking mechanism is made of a glass fiber and resin composite material.

[0032] Install and fix the chassis 2 and the frame 1: Fix the chassis 2 on the outer edge of the through-hole provided in the frame 1 so that the protection grooves 201 and the soldering holes 202 on the chassis 2 are clamped in the space of the through-hole.

[0033] Perform soldering process for SMT and THT ultra-fine pitch mixed mounting: S100: Print the solder paste of the surface-mounted components to be soldered onto the PCB board; S200: Place the surface-mounted components at the solder paste on the PCB board; S300: Perform reflow soldering on the PCB board to achieve the soldering of the surface-mounted components and the PCB board; S400: Insert the via-hole components to be soldered into the holes preset on the PCB board; S500: Fix the PCB board on the soldering device, and use a wave soldering machine on the soldering device to achieve the soldering of the via-hole components and the PCB board. In step S500, the PCB board is fixed in the fixed area 107. After the PCB board is fixed to the soldering device, the following effects are produced: The chassis 2 contacts the exposed surface of the pins of the via-hole components on the PCB board. The protection groove 201 and the PCB board form a sealed space. The via-hole components of the PCB board pass through the soldering holes 202 to expose the pins and the via-hole solder pads in the space on the second end face of the frame 1. The soldering work of the wave soldering machine is also completed in the space on the second end face.

[0034] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "inner" and "outer" is the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the products of this application are usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0035] It should also be noted that unless otherwise clearly specified and limited, the terms "set" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0036] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific identification content executed by the above-described system and device can refer to the corresponding process in the foregoing method embodiments.

[0037] The embodiments of the present invention have been described in detail above in conjunction with the drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A welding method for SMT and THT ultra-fine pitch mixed assembly, applied to the PCB welding process of SMT and THT ultra-fine pitch mixed assembly, characterized in that: The process includes the following steps which are performed in sequence: Print the solder paste of the mounted components to be soldered onto the PCB board; The mounting components are arranged at the solder paste of the PCB board; Reflow soldering the PCB board to achieve soldering of the mounted components to the PCB board; Inserting the through-hole components to be soldered into the pre-set holes on the PCB board; The PCB board is fixed on a welding device, and the welding device is used to weld the through-hole component and the PCB board through a wave soldering machine.

2. The welding method for ultra-fine pitch mixed assembly of SMT and THT according to claim 1, characterized in that: The welding device includes a frame and a chassis, wherein the first end face of the frame is provided with a fixing area for fixing the PCB board, and the chassis is provided with a plurality of protection grooves and a plurality of welding holes, wherein the protection grooves are used to cover the patch components of the PCB board, and the size and position of the protection grooves are adapted to the position and size of the patch component area of ​​the PCB board, and the welding holes provide space for the through-hole components of the PCB board to pass through and weld, and the size of the welding holes is adapted to the size of the pads of the through-holes, and a through-hole penetrating therethrough is provided on the first end face with space for accommodating the plurality of protection grooves and the plurality of welding holes, and the chassis is fixed to the outer edge of the through-hole by a first fixing member.

3. The welding method for ultra-fine pitch mixed assembly of SMT and THT according to claim 2, characterized in that: The welding device further comprises at least one support bar, and the support bar is fixed to the edge of the first end surface by at least one second fixing member.

4. The welding method for ultra-fine pitch mixed assembly of SMT and THT according to claim 3, characterized in that: The first fixing member and the second fixing member are both made of stainless steel screws.

5. The welding method for ultra-fine pitch mixed assembly of SMT and THT according to claim 2, characterized in that: The first end surface is provided with a first groove and a second groove, the first groove is provided at the outer side of the edge of the fixing area, and the second groove is provided at the outer side of the edge of the through hole.

6. The welding method for SMT and THT ultra-fine pitch mixed assembly according to claim 2, characterized in that: The frame is provided with at least two locking mechanisms for fixing the PCB board, and the locking mechanism includes a fixed shaft, an elastic member and a limit buckle; a limit portion is provided at the first end of the fixed shaft, the limit buckle and the elastic member are sleeved on the fixed shaft, and the elastic member is located between the limit portion and the limit buckle, and the fixed shaft is fixedly connected to the outer side of the edge of the fixed area.

7. The welding method for ultra-fine pitch mixed assembly of SMT and THT according to claim 6, characterized in that: The fixed shaft is made of stainless steel, the elastic member is a stainless steel screw, and the limit buckle is made of a glass fiber and resin composite.

8. A welding device for ultra-fine pitch mixed welding of SMT and THT, comprising a frame and a chassis, wherein the chassis is provided with a plurality of protection grooves for protecting patch components and a plurality of welding holes for providing welding space for through-hole components, and the welding method according to claims 1-7 is used to weld an ultra-fine pitch mixed PCB board of SMT and THT, characterized in that: The protection groove includes two protection walls and a shield. The protection wall is fixed on the edge of the chassis. The protection wall is located at the vertical plane of the connection between the patch component pad and the through-hole component pad of the fixed PCB board and extends toward the through-hole space opened in the frame. The top ends of two adjacent protection walls are connected by the shield. The height of the protection wall is adapted to the height of the protected patch component. The height of the protection wall is 0.5-6mm, and the thickness of the protection wall is 0.3mm. The frame is made of synthetic stone and the chassis is made of titanium alloy.

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