A surface mount fuse reflow soldering process

Abstract

A reflow soldering process for surface mount fuses includes the following steps: Step A: attaching metal inner caps to both ends of the fuse tube; Step B: placing the surface mount fuse tubes with metal inner caps into a wire threading reel; Step C: connecting the rows of surface mount fuse tubes laid flat on the wire threading reel in a beaded manner; Step D: winding the connected surface mount fuse tubes sequentially left and right around a metal winding fixture; Step E: arranging the metal winding fixture in a metal dispensing frame; Step F: applying solder paste to the metal inner caps at both ends of all surface mount fuse tubes; Step G: placing the surface mount fuse tubes on the metal winding fixture horizontally; Step H: sending the metal soldering frame into the reflow oven cavity to complete the soldering process between the surface mount fuse tubes and the fuse wire; Step I: cutting the soldered surface mount fuse tubes off the metal winding fixture and attaching metal outer caps. This invention solves the problems of high resistance and low production soldering efficiency in existing products.

Description

Technical Field

[0001] This invention relates to the field of circuit protection component manufacturing, and more specifically to a surface mount fuse reflow soldering process. Background Technology

[0002] Surface mount fuses are mainly divided into two categories: one is a thick film surface mount fuse formed by screen printing on a ceramic substrate, drying and sintering layer by layer. Its main sizes include 0402, 0603, 1206 and 1815, etc. Because the printed thick film pattern of this type of surface mount fuse is easily affected by the viscosity of the paste, the printed shape and pattern are often easily distorted and deformed, and the thickness cannot be precisely controlled. This results in a large dispersion of the resistance value of the printed product, a high resistance failure rate, and unstable fusing characteristics, which seriously affects the product quality and stability of surface mount fuses. Another type is the square brick-shaped metal wire chip fuse. Its welding process is mainly an automatic wire threading and welding process. The welding process can only be done one wire at a time. The process is to weld the first end cap first and then the second end cap. Because there is air in the tube after the first end cap is welded, when welding the second end cap, the air in the tube is heated and expelled. This often causes the molten solder of the second end cap to be discharged outward, resulting in solder overflow. The overflowing solder can easily fall onto the automatic wire threading and welding machine table or into the machine, making the table dirty and difficult to clean. In severe cases, it can easily damage the equipment.

[0003] In addition, since soldering uses solder wire, which has a low melting point, and surface mount fuses need to be soldered onto the PCB board for use at the customer's end, the low melting point of this type of soldering process often leads to solder remelting (because the solder melts), which can easily cause problems such as poor soldering or no power when the customer uses the product, affecting the quality and reliability of the product. On the other hand, if lead-containing solder wire (with a high melting point) is used, its use is often restricted because lead is a heavy metal and harmful substance, and it can also affect physical and mental health.

[0004] In view of this, the inventors have developed this invention through in-depth conception, active research and improvement, and trial production, in order to solve the problems of low soldering efficiency, solder overflow, and high product resistance defect rate in the production of existing surface mount fuses. Summary of the Invention

[0005] The purpose of this invention is to provide a reflow soldering process for surface mount fuses, which can solve problems such as large resistance dispersion, high resistance defects, low production soldering efficiency, and solder overflow in existing products.

[0006] To achieve the above objectives, the solution of the present invention is:

[0007] A surface mount fuse reflow soldering process includes the following steps:

[0008] Step A: After attaching metal inner end caps to both ends of the fuse tube, a patch fuse tube is formed. The metal inner end caps have through holes for the fuse wire to pass through.

[0009] Step B: Place the patch fuse tubes with metal inner caps into a wire threading reel, arrange multiple patch fuse tubes one after the other, and lay multiple rows of patch fuse tubes flat on the wire threading reel;

[0010] Step C: Hang the filament-shaped fuse inside a threading needle, and use the threading needle to connect the rows of surface-mount fuse tubes laid flat on the threading reel in a bead-like manner to form a series of surface-mount fuse tubes ready for use.

[0011] Step D: Fix one end of the fuse with the chip fuse tube attached to it to one end of a metal winding clamp, and then wind the attached chip fuse tube around the metal winding clamp in sequence until it is fully wound. Fix the other end of the fuse to the other end of the metal winding clamp to complete the winding and fixing.

[0012] Step E: Arrange and position each metal wire-wound clamp with the fuse wire in a metal dispensing frame, with both ends of each metal wire-wound clamp positioned on the two sides of the metal dispensing frame.

[0013] Step F: Apply solder paste with a high melting point to one end of the inner metal cap of the surface mount fuse tube connected in series with the metal wire winding fixture using a dispensing device. The solder paste fills the through hole of the inner metal cap. After the inner metal caps of all surface mount fuse tubes on the entire metal dispensing frame have been covered with solder paste, apply solder paste to the inner metal caps of the other end of each surface mount fuse tube until the inner metal caps of both ends of all surface mount fuse tubes have been covered with solder paste.

[0014] Step G: Arrange all the metal wire winding jigs with solder paste applied in an array and position them in a metal soldering frame, and place the surface mount fuse tubes on the metal wire winding jigs in a horizontal position, and ensure that the surface mount fuse tubes on adjacent metal wire winding jigs do not touch each other.

[0015] Step H: Send the metal welding frame into the reflow oven cavity to complete the welding process between the patch fuse tube and the fuse wire;

[0016] Step 1: Cut the soldered surface mount fuse tube off the metal winding jig, and finally put on two metal outer end caps to complete the manufacturing process of the surface mount fuse reflow soldering process.

[0017] Furthermore, in step A, the fuse tube is a square tube with square or round openings at both ends. The metal inner cap matches the opening of the fuse tube and has a through hole in the middle.

[0018] Furthermore, in step B, the wire threading reel is provided with multiple spaced slots. The slots are recessed downwards in the surface of the wire threading reel to form strip-shaped grooves for positioning and placing fuse tubes. Multiple patch fuse tubes are laid flat in sequence in the slots and located on the same axis, which facilitates the wire threading needle to thread the wire.

[0019] Furthermore, in step D, the metal winding clamp includes multiple limiting slots for fixing the patch fuse tubes arranged at intervals on the left and right sides of a long strip-shaped support rod. The patch fuse tubes are vertically located on both sides of the metal winding clamp, and adjacent patch fuse tubes on the same side of the metal winding clamp do not contact each other. The patch fuse tubes on the left and right sides are arranged in an alternating staggered distribution.

[0020] Furthermore, the support rod includes a longitudinal strip with two parallel transverse strips. The longitudinal strip is perpendicularly inserted through the middle of the upper and lower transverse strips. The two transverse strips extend on both sides of the longitudinal strip to form side strips. The fuse tube is sandwiched between the two side strips. Multiple limiting grooves are arranged at intervals on the side strips. The shape of the limiting grooves corresponds to the shape of the metal inner end cap, so that the two corresponding limiting grooves on the upper and lower side strips on the same side are symmetrical. A limiting groove position is formed between the two symmetrical upper and lower limiting grooves. The limiting grooves on different sides are spaced apart by half a limiting groove position.

[0021] Furthermore, in step E, the metal dispensing frame is provided with multiple pairs of first positioning slots for positioning and mounting each metal wire winding clamp at both ends. The metal dispensing frame includes multiple pairs of symmetrical first positioning slots on a set of opposite sides of a metal frame.

[0022] Furthermore, the solder paste in step F is a high-temperature lead-free solder paste with a melting point range of 245-285℃. The solder paste is applied at the connection between the fuse and the inner metal cap, and the amount of solder paste is 4±2mg.

[0023] Furthermore, in step F, after all the solder paste has been applied to the first end caps of all the surface mount fuse tubes, another metal adhesive application frame is put on, and then the surface mount fuse tubes on the metal winding fixture are flipped upside down, and the second end caps of the metal winding fixture that are not coated with solder paste at the bottom are flipped upside down.

[0024] Furthermore, in step G, the metal welding frame includes multiple pairs of symmetrical second positioning slots on a set of opposite sides of a metal frame. The second positioning slots enable the metal winding clamp to be rotated 90 degrees and then laid flat for insertion.

[0025] After adopting the above solution, the welding speed of the present invention is significantly improved compared with the existing automatic wire threading machine for surface mount fuses (which requires threading and welding wires one by one). At the same time, the use of lead-free solder paste during the welding process is more environmentally friendly. In addition, the surface mount fuse tube is horizontal during welding, which avoids the problem of solder melting when the customer uses low melting point lead-free solder wire during reflow soldering. The fuse wire and end cap on the surface mount fuse tube in this process are well welded, and there will be no defects such as bulging or leakage. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the patch fuse tube in this invention;

[0027] Figure 2 This is an exploded view of the patch fuse tube in this invention;

[0028] Figure 3 This is a schematic diagram of the wire threading disc in the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the wire threading spool after the patch fuse tube is laid flat in this invention;

[0030] Figure 5 This is a schematic diagram of the metal winding clamp in this invention;

[0031] Figure 6 This is a top view of the metal winding clamp in this invention;

[0032] Figure 7 This is a schematic diagram of the structure of the metal winding clamp in this invention, which connects the patch fuse tube in series with the winding.

[0033] Figure 8 This is a schematic diagram of the metal dispensing frame structure in this invention;

[0034] Figure 9 A schematic diagram showing the structure of a metal winding clamp that has been completed and bound to a metal adhesive frame;

[0035] Figure 10 A schematic diagram of a metal wire-winding fixture with solder paste applied being placed horizontally in a metal soldering frame;

[0036] Figure 11 This is a schematic diagram of the fuse tube after horizontal welding.

[0037] Figure 12 , Figure 13 This is a schematic diagram of the fuse tube after it has been welded upright. Implementation

[0038] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0039] This invention discloses a reflow soldering process for a surface mount fuse. The surface mount fuse includes metal outer caps (not shown in the figure) fitted at both ends of a surface mount fuse tube 1. The surface mount fuse tube 1 includes metal inner caps 12 fitted at both ends of a fuse tube body 11. A fuse wire is threaded inside the fuse tube body 11, and the two ends of the fuse wire can be soldered to the metal inner caps. Combined with... Figures 1 to 10 As shown, the present invention includes the following steps.

[0040] Step A: After attaching metal inner end caps 12 to both ends of the fuse tube body 11, a patch fuse tube 1 is formed (e.g., Figure 1 As shown), the inner metal cap 12 has a through hole 121 for the fuse to pass through;

[0041] Step B: Place the patch fuse tube 1 with the metal inner end cap 12 already fitted into a wire threading reel 2. When placing it in, arrange multiple patch fuse tubes 1 one after the other, spreading them out in multiple rows on the wire threading reel 12 (e.g., Figure 4 (as shown)

[0042] Step C: Hang the filament-shaped fuse 3 inside a threading needle (not shown in the figure), and use the threading needle to connect the rows of patch fuse tubes laid flat on the threading reel in a bead-like manner to form a series of patch fuse tubes ready for use.

[0043] Step D: Tie one end of the fuse 3 with the surface mount fuse tube connected to it to a metal winding clamp 4, and then wind the connected surface mount fuse tube 1 sequentially left and right on the metal winding clamp in a certain direction until it is fully wound. Tie the other end of the fuse to the other end of the metal winding clamp to complete the winding and binding process (e.g., Figure 7 (as shown)

[0044] Step E: Arrange and position each metal wire-wound clamp 4 with the fuse wire wound in a metal dispensing frame 5, with both ends of each clamp positioned on the two sides of the metal dispensing frame (e.g., ...). Figure 9 (as shown)

[0045] Step F: Apply solder paste with a high melting point to one end of the inner metal cap of the surface mount fuse tube connected in series with the metal wire winding fixture using a dispensing device. The solder paste fills the through hole of the inner metal cap. After the inner metal caps of all surface mount fuse tubes on the entire metal dispensing frame have been covered with solder paste, apply solder paste to the inner metal caps of the other end of each surface mount fuse tube until the inner metal caps of both ends of all surface mount fuse tubes have been covered with solder paste.

[0046] Step G: Arrange all the metal wire winding jigs with solder paste applied in an orderly manner within a metal soldering frame 6, ensuring that the surface mount fuse tubes 1 on the metal wire winding jigs 4 are placed horizontally, and that the surface mount fuse tubes on adjacent metal wire winding jigs 4 do not contact each other (e.g., Figure 10 (as shown)

[0047] Step H: Place the metal welding frame on the welding guide rail of the reflow oven (not shown in the figure). The welding guide rail of the reflow oven will send the metal welding frame into the reflow oven cavity to complete the welding process of the patch fuse tube and the fuse wire.

[0048] Step 1: Cut the soldered surface mount fuse tube off the metal winding jig (not shown in the figure), and finally put on two metal outer end caps to complete the manufacturing process of the surface mount fuse reflow soldering process.

[0049] Specifically, in step A above, such as Figure 1 , Figure 2 As shown, the fuse tube 11 is a square tube, and the openings 111 at both ends of the square tube can be square or round. The metal inner cap 12 matches the openings 111 of the fuse tube 11. In this embodiment, the openings 111 are round, and the metal inner cap 12 is a circular cover. The metal inner cap 12 has a through hole 121 in the middle for the fuse wire to pass through.

[0050] In step B, such as Figure 3 , Figure 4 As shown, the threading reel 2 may include side baffles 22 protruding from three sides of a square base plate 21. One side of the base plate 21 forms an opening, and the top surface of the base plate 21 forms a reel surface. The threading reel 2 has multiple spaced slots 23. The slots 23 are recessed downwards in the reel surface to form strip-shaped grooves for positioning fuse tubes 11. One end of the slot 23 corresponds to the side of the base plate 21 with the opening. In this embodiment, the fuse tube 11 is a square tube, and the slots form strip-shaped grooves with a right-angled triangular cross-section to facilitate the placement and positioning of the patch fuse tubes 1. In use, multiple patch fuse tubes 1 are laid out one after another in the slots 23 and located on the same axis, which facilitates the threading operation of the threading needle.

[0051] In step C, the wire strip 3 can be hung in the hole at the bottom of a threading needle. The length of the threading needle can be greater than the length of the patch fuse tube after the metal inner end cap has been fitted. When connecting them in series, the patch fuse tubes 1 are placed in a row in the threading reel 2, which facilitates operation and greatly improves the efficiency of operation. In step D, one end of the fuse with the patch fuse tubes connected can be tied to one end of the metal winding clamp 4, and the connected patch fuse tubes 1 are wound sequentially left and right on the metal winding clamp 4 in a certain direction. After winding, the other end of the fuse is tied to the other end of the metal winding clamp, completing the winding and binding process.

[0052] In step D, combined Figures 5 to 7 As shown, the metal winding clamp 4 includes multiple limiting slots for fixing the chip fuse tubes on both sides of a long strip-shaped support rod. Two rows of chip fuse tubes 1 are vertically placed on both sides of the metal winding clamp 4. Adjacent chip fuse tubes 1 on the same side of the metal winding clamp 4 do not contact each other, and the chip fuse tubes 1 on the left and right sides are arranged in an alternating staggered distribution. The support rod may include a longitudinal strip 41 with two parallel transverse strips 42. The longitudinal strip 41 is vertically inserted through the middle of the two transverse strips 42, with a cross-section resembling an "I" shape. The two transverse strips 43 extend from both sides of the longitudinal strip to form side strips 420, and the fuse tube 11 is clamped between the two side strips 420. Multiple limiting slots 421 are evenly distributed on the side strips 420, forming a certain interval to avoid contact between adjacent chip fuse tubes. The shape of the limiting groove 421 corresponds to the shape of the metal inner end cap 12. In this embodiment, the limiting groove 421 forms a semi-circular opening to accommodate the circular metal inner end cap 12. The two corresponding limiting grooves 421 on the same side upper and lower strips 420 are symmetrical, forming a limiting groove between them for the patch fuse tube 1 to be inserted. The limiting grooves 421 on different sides can be spaced apart by half a limiting groove position to form an alternating staggered distribution. Distributing the surface-mount fuse tubes 1 on the left and right sides of the metal winding clamp 4 can increase the number of wires that can be wound. The staggered distribution of the products on the left and right sides of the metal winding clamp 4 allows the fuse tubes 1 to be wound around the metal winding clamp 4 in a spiral manner during the winding and binding process in step D. This prevents the fuse 3 from getting tangled, twisted, bent, or damaged, and makes it easier for the fuse 3 to be wound around the product and fixed to the metal winding clamp 4. However, if the staggered method is not used, the fuse 3 is prone to twisting, bending, or damage when winding the third product after winding the first and the second product on the opposite side, and it is also inconvenient to wind.

[0053] In step E, combined Figure 8 , Figure 9As shown, the metal dispensing frame 5 is provided with multiple pairs of first positioning slots 511 for positioning and holding each metal wire winding clamp 4 at both ends. The metal dispensing frame 5 includes multiple pairs of symmetrical first positioning slots 511 on a set of opposite sides 51 of a metal frame for placing each metal wire winding clamp 4. There is a certain distance between two adjacent first positioning slots 511 to prevent the patch fuse tubes 1 on adjacent metal wire winding clamps 4 from touching. Through the positioning function of the first positioning slots, each metal wire winding clamp 4 can be prevented from tilting or leaning.

[0054] The solder paste used in step F is a high-temperature lead-free solder paste with a melting point range of 245-285℃. The solder paste is applied at the connection point between the fuse wire and the inner metal cap. The amount of solder paste is 4±2mg to ensure sufficient solder spread for a firm weld between the fuse wire and the inner metal cap, without any holes appearing on the inner metal cap. In step F, after all the top caps of the first end of all surface mount fuse tubes 1 have been soldered, another metal dispensing frame can be placed on top. Then, the surface mount fuse tubes on the metal winding fixture are flipped upside down, and the second cap at the bottom of the metal winding fixture that has not been soldered is flipped upwards to facilitate the soldering process on the inner metal caps at both ends of the surface mount fuse tubes.

[0055] In step G, such as Figure 10 As shown, the metal welding frame 6 includes multiple pairs of symmetrical second positioning slots 611 on a set of opposite sides 61 of a metal frame. The second positioning slots 611 allow the metal winding fixture 4 to be rotated 90 degrees and then placed horizontally. There is a certain distance between adjacent second positioning slots 611 to form a gap, ensuring that the surface-mount fuse tubes 1 on adjacent metal winding fixtures 4 are separated and do not contact each other. This prevents the products from absorbing heat from each other during subsequent processes, i.e., reflow soldering, which would prevent the solder paste on the products from melting and spreading. There are no special requirements for changing the metal winding fixture 4 from an upright position to a horizontal position; it can be placed manually or using a fixture, as long as it is convenient to operate. In addition, the length of the longitudinal strip 41 in the support rod of the metal winding clamp 4 can be made equal to the length of the transverse strip 42. The first positioning slot 511 and the second positioning slot 611 are the same. The metal dispensing frame 5 and the metal welding frame 6 can be the same and can be used directly or replaced. For example, the metal winding clamp 4 can be flipped 90 degrees in the metal dispensing frame 5 so that the patch fuse tube 1 is laid horizontally.

[0056] In step G, the surface mount fuse tube 1 on the metal winding fixture is placed horizontally. When the metal solder frame 6 passes through the reflow oven, the solder paste at both ends of the surface mount fuse tube 1 seals the tube body. During reflow, the tube body is heated, and because it is horizontal, the gas inside the tube is expelled to the left and right ends. Simultaneously, the solder paste is in a molten state (solid-to-liquid transition process). The solder paste on the end caps re-seals the inner end cap holes due to its own gravity (e.g., ...). Figure 11 As shown), this ensures a good solder joint between the fuse wire and the end cap on the surface mount fuse tube, preventing defects such as leaks. However, if the tube is soldered vertically in a reflow oven, the tube will heat up, causing air inside to rise and break through the solder paste, resulting in air pockets in the solder paste on the upper end cap (as shown). Figure 12 As shown), the solder paste on the lower cap melts due to its own weight and sags, which can also cause solder bulges or pinholes (as shown). Figure 13 As shown in the figure, when the fuse is exactly at the solder paste drain hole, poor soldering, such as cold solder joints, is likely to occur.

[0057] After adopting the above solution, the surface mount fuse of the present invention uses a reflow soldering process, which significantly improves the soldering speed compared to the automatic wire threading machine soldering used in existing surface mount fuses (which requires threading and soldering wires one by one). Simultaneously, the use of lead-free solder paste during the soldering process is more environmentally friendly. Furthermore, the surface mount fuse tube is horizontal during soldering, avoiding the problem of solder melting during reflow soldering when using low-melting-point lead-free solder wire. In this process, the fuse wire and end cap on the surface mount fuse tube are well soldered, without bulging, leakage, or other defects. The present invention solves the problems of large resistance dispersion, high resistance defects, low production soldering efficiency, and solder overflow in existing products.

[0058] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A reflow soldering process for surface mount fuses, characterized in that, Includes the following steps, Step A: After attaching metal inner end caps to both ends of the fuse tube, a patch fuse tube is formed. The metal inner end caps have through holes for the fuse wire to pass through. Step B: Place the patch fuse tubes with metal inner caps into a wire threading reel, arrange multiple patch fuse tubes one after the other, and lay multiple rows of patch fuse tubes flat on the wire threading reel; Step C: Hang the filament-shaped fuse inside a threading needle, and use the threading needle to connect the rows of surface-mount fuse tubes laid flat on the threading reel in a bead-like manner to form a series of surface-mount fuse tubes ready for use. Step D: Fix one end of the fuse tube with the surface mount fuse tube attached to one end of a metal winding clamp, and then wind the surface mount fuse tube around the metal winding clamp in sequence from left to right until the metal winding clamp is fully wound. The surface mount fuse tube is positioned vertically on both sides of the metal winding clamp. Fix the other end of the fuse tube to the other end of the metal winding clamp to complete the winding and fixing. Step E: Arrange and position each metal wire-wound clamp with the fuse wire in a metal dispensing frame, with both ends of each metal wire-wound clamp positioned on the two sides of the metal dispensing frame. Step F: Apply solder paste with a high melting point to one end of the inner metal cap of the surface mount fuse tube connected in series with the metal wire winding fixture using a dispensing device. The solder paste fills the through hole of the inner metal cap. After the inner metal caps of all surface mount fuse tubes on the entire metal dispensing frame have been covered with solder paste, apply solder paste to the inner metal caps of the other end of each surface mount fuse tube until the inner metal caps of both ends of all surface mount fuse tubes have been covered with solder paste. Step G: Arrange all the metal wire winding jigs with solder paste applied in an array and position them in a metal soldering frame, and place the surface mount fuse tubes on the metal wire winding jigs in a horizontal position, and ensure that the surface mount fuse tubes on adjacent metal wire winding jigs do not touch each other. Step H: Send the metal welding frame into the reflow oven cavity to complete the welding process between the patch fuse tube and the fuse wire; Step 1: Cut the soldered surface mount fuse tube off the metal winding jig, and finally put on two metal outer end caps to complete the manufacturing process of the surface mount fuse reflow soldering process; In step F, after all the solder paste has been applied to the first end caps of all the surface mount fuse tubes, another metal glue application frame is put on, and then the surface mount fuse tubes on the metal winding fixture are flipped upside down, and the second end caps of the bottom of the metal winding fixture that have not been soldered are flipped upside down. In step G, the metal welding frame includes multiple pairs of symmetrical second positioning slots on a set of opposite sides of a metal frame. The second positioning slots enable the metal winding clamp to be rotated 90 degrees and then inserted horizontally.

2. The surface mount fuse reflow soldering process as described in claim 1, characterized in that: In step A, the fuse tube is a square tube with square or round openings at both ends. The metal inner cap matches the opening of the fuse tube and has a through hole in the middle.

3. The surface mount fuse reflow soldering process as described in claim 1 or 2, characterized in that: In step B, the wire threading spool is provided with multiple spaced slots. The slots are recessed downwards in the surface of the wire threading spool to form strip-shaped grooves for positioning and placing fuse tubes. Multiple patch fuse tubes are laid flat in sequence in the slots and located on the same axis, which facilitates the wire threading needle to thread the wire.

4. The surface mount fuse reflow soldering process as described in claim 1, characterized in that: In step D, the metal winding clamp includes multiple limiting slots arranged at intervals on the left and right sides of a long strip-shaped support rod for fixing the patch fuse tubes. Adjacent patch fuse tubes on the same side of the metal winding clamp do not contact each other, and the patch fuse tubes on the left and right sides are arranged in an alternating staggered distribution.

5. The surface mount fuse reflow soldering process as described in claim 4, characterized in that: The support rod includes a longitudinal strip with two parallel transverse strips. The longitudinal strip is perpendicularly inserted through the middle of the upper and lower transverse strips. The two transverse strips extend on both sides of the longitudinal strip to form side strips. The fuse tube is sandwiched between the two side strips. Multiple limiting grooves are arranged at intervals on the side strips. The shape of the limiting grooves corresponds to the shape of the metal inner end cap, so that the two corresponding limiting grooves on the upper and lower side strips on the same side are symmetrical. A limiting groove position is formed between the two symmetrical upper and lower limiting grooves. The limiting grooves on different sides are separated by half a limiting groove position.

6. The surface mount fuse reflow soldering process as described in claim 1, characterized in that: In step E, the metal dispensing frame is provided with multiple pairs of first positioning slots for positioning and mounting each metal wire winding clamp at both ends. The metal dispensing frame includes multiple pairs of symmetrical first positioning slots on a set of opposite sides of a metal frame.

7. The surface mount fuse reflow soldering process as described in claim 1, characterized in that: The solder paste in step F is a high-temperature lead-free solder paste with a melting point range of 245-285℃. The solder paste is applied at the connection between the fuse and the inner metal cap, and the amount of solder paste is 4±2mg.

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