Rolling equipment and method for adding metal wire into solder

Abstract

The invention belongs to the technical field of welding flux processing, and particularly relates to rolling equipment and method for adding metal wires into welding flux, and the rolling equipment comprises a rack, a rolling wheel is arranged in the middle of the rack, three sets of unwinding rollers are arranged on the left side of the rack, a winding assembly is arranged on the right side of the rack, and the winding assembly comprises a circular shell fixed to the rack; a circular plate is rotatably mounted on the front side of the circular shell, a first motor is mounted in the middle of the circular shell, an output shaft of the first motor is connected with the circular plate, second motors are mounted on the left and right sides of the circular plate, circular seats are mounted on output shafts of the second motors, and winding rollers are mounted on the front sides of the circular seats. Through motor driving, the full-automatic process from unwinding, rolling to winding of welding flux and metal wires is achieved, manual operation is greatly reduced, the production efficiency is improved, the double-winding-roller design is adopted, the circular plate is driven by the motor to rotate, alternating work of the winding rollers is achieved, the winding rollers do not need to be replaced after shutdown, continuous production is guaranteed, and the production efficiency is improved. And the winding efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of solder processing, and in particular relates to a rolling device and a method for adding metal wire into solder. Background Art

[0002] Solder plays a vital role in the electronics industry. It is not only used to achieve electrical and mechanical connections within components and between components and printed circuit boards, but also with the miniaturization trend of electronic components and the advancement of surface assembly technology, the demand for solder's microstructural stability, mechanical properties, and especially creep resistance is growing.

[0003] However, for some heavier modules, tin overflow is prone to occur during the welding process, as well as welding defects caused by poor exhaust.

[0004] When welding certain materials, such as DBC boards, slight warping may occur during the welding process due to the influence of thermal stress. Traditional solder lacks sufficient support in the molten state, which may cause tilting or offset during welding, and it is difficult to restore the original shape after welding. If the surface of the material after welding is uneven, the thicker part will have a higher thermal resistance, which will reduce the service life of the product.

[0005] In patent No. CN201611036462, a method is proposed to achieve the purpose of height limitation and exhaust by grooving the surface of the welding piece and embedding metal wires. Although this method can achieve the expected effect, its process complexity is relatively high, and the distinction between the front and back sides of the welding piece will affect production efficiency. In addition, if the filled metal wire is round, the metal wire may be offset during the welding process due to the effect of surface tension. For the grooving of special-shaped structures, if the accuracy is not enough, the metal wire cannot be completely matched, which will leave bubbles during the molding process, thereby affecting the welding quality. Summary of the invention

[0006] The purpose of the present invention is to provide a rolling device and method for adding metal wire into solder, so as to solve the problems raised in the background technology.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0008] A rolling device for adding metal wire to solder, comprising a frame, a rolling wheel is arranged in the middle of the frame, three sets of unwinding rollers are arranged on the left side of the frame, a winding assembly is arranged on the right side of the frame, the winding assembly comprises a circular shell fixed to the frame, a circular plate is rotatably mounted on the front side of the circular shell, a first motor is mounted in the middle of the circular shell, an output shaft of the first motor is connected to the circular plate, a second motor is mounted on both the left and right sides of the circular plate, a circular seat is mounted on the output shaft of the second motor, and a winding roller is mounted on the front side of the circular seat;

[0009] The winding roller is composed of a fixed semicircular bar and a movable semicircular bar, the fixed semicircular bar is fixedly connected to the circular seat, the circular seat is provided with a mounting groove, a gear is rotatably mounted in the mounting groove, the rear end of the movable semicircular bar is connected to the gear, a rack meshing with the gear is slidably arranged on the lower side of the mounting groove, a first spring is arranged between the front side of the rack and the mounting groove, a push rod is connected to the rear side of the rack, and a semicircular boss matching the push rod is fixed on the lower side of the circular shell;

[0010] The fixed semicircular bar and the movable semicircular bar together form a circular column with a gap therebetween. A cutter is fixed on the inner side of the movable semicircular bar. A knife groove matching the cutter is provided on the fixed semicircular bar. A clamping assembly is provided on one side of the movable semicircular bar.

[0011] The clamping assembly includes a sliding groove opened by the movable semicircular bar, a sliding bar is slidably arranged in the sliding groove, a second spring is arranged between the sliding bar and the side wall of the movable groove, and a pressing plate abutting against the fixed semicircular bar is arranged at the end of the sliding bar.

[0012] A connecting shaft is fixed to the end of the circular seat, a connecting seat is fixed to the connecting shaft, a mounting shell matching the connecting seat is fixed to the output shaft of the second motor, and a connecting component is provided between the connecting seat and the mounting shell.

[0013] The connecting assembly includes a slide groove provided on the connecting seat, a locking block slidingly arranged in the slide groove, a locking groove matching the locking block in the mounting shell, a third spring provided between the locking block and the slide groove, a movable groove provided in the middle of the connecting shaft, a movable block slidingly arranged in the movable groove, the movable block being connected to the locking block via a first pull wire, a first handle being provided at the front end of the fixed semicircular bar, the first handle being connected to the movable block via a second pull wire, and a second handle located outside the first handle being also fixed at the front end of the fixed semicircular bar.

[0014] A rolling method of a rolling device for adding a metal wire into a solder, comprising the following steps;

[0015] Step 1: The three groups of unwinding rollers are respectively placed with solder sheets, metal wires and solder sheets, and stacked in the order of solder sheets, metal wires and solder sheets;

[0016] Step 2: Start the rolling wheel set on the frame, roll the stacked solder sheets and metal wires through the rolling wheel, and roll the processed solder through the winding assembly;

[0017] Step 3: When the winding amount of the left winding roller is about to reach the standard, start the first motor to drive the circular plate to rotate clockwise, and the left winding roller continues to wind the solder until the right winding roller moves to the left side. The movable semicircular bar of the winding roller moves downward, and the left side of the solder is fixed by the clamping assembly. At the same time, the cutter in the middle of the movable semicircular bar moves downward into the knife groove to cut off the solder, so that the winding roller can continue to wind the solder, realizing automatic handover and winding without stopping.

[0018] The present invention realizes a fully automated process from unwinding, rolling to winding of solder and metal wire through motor drive, greatly reduces manual operation and improves production efficiency. It adopts a double winding roller design and drives the circular plate to rotate through a motor to realize alternating operation of the winding rollers. There is no need to stop the machine to replace the winding rollers, thus ensuring continuous production and greatly improving the winding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further illustrated by means of the non-limiting examples given in the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of an embodiment of a rolling device for adding metal wire into solder according to the present invention;

[0021] Figure 2 The cross-sectional structure of the circular shell of the present invention is shown in FIG. Figure 1 ;

[0022] Figure 3 The cross-sectional structure of the circular shell of the present invention is shown in FIG. Figure 2 ;

[0023] Figure 4 The cross-sectional structure of the circular shell of the present invention is shown in FIG. Figure 3 ;

[0024] Figure 5 for Figure 4 A schematic diagram of the structure enlargement at the center A;

[0025] Figure 6 for Figure 4 A schematic diagram of the structure enlarged at B in the middle;

[0026] Figure 7 It is a schematic diagram of the cross-sectional structure of the winding roller of the present invention;

[0027] Figure 8 It is the SAT diagram after soldering of the present invention;

[0028] Fig. 9 The cross-sectional morphology of the solder after welding of the present invention;

[0029] Fig.10 This is the SAT diagram of the solder of the present invention under TC test.

[0030] The main component symbols are described as follows:

[0031] Frame 1, rolling wheel 11, unwinding roller 12, circular shell 2, circular plate 21, first motor 22, second motor 23, circular seat 24, winding roller 25, fixed semicircular bar 251, movable semicircular bar 252, mounting groove 241, gear 242, rack 243, first spring 244, push rod 245, semicircular boss 26, cutter 253, knife groove 254, sliding groove 3, sliding bar 31, second spring 32, pressure plate 33, connecting shaft 4, connecting seat 41, mounting shell 42, sliding groove 411, locking block 412, locking groove 421, third spring 413, movable groove 43, movable block 44, first pull wire 45, first handle 46, second pull wire 47, second handle 48. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0033] like Figure 1-10 As shown, a rolling device for adding metal wire to solder of the present invention comprises a frame 1, a rolling wheel 11 is arranged in the middle of the frame 1, three sets of unwinding rollers 12 are arranged on the left side of the frame 1, a winding assembly is arranged on the right side of the frame 1, and the winding assembly comprises a circular shell 2 fixed on the frame 1, a circular plate 21 is rotatably installed on the front side of the circular shell 2, a first motor 22 is installed in the middle of the circular shell 2, an output shaft of the first motor 22 is connected to the circular plate 21, a second motor 23 is installed on both sides of the circular plate 21, a circular seat 24 is installed on the output shaft of the second motor 23, and a winding roller 25 is installed on the front side of the circular seat 24;

[0034] The winding roller 25 is composed of a fixed semicircular bar 251 and a movable semicircular bar 252. The fixed semicircular bar 251 is fixedly connected to the circular seat 24. The circular seat 24 is provided with a mounting groove 241. A gear 242 is rotatably mounted in the mounting groove 241. The rear end of the movable semicircular bar 252 is connected to the gear 242. A rack 243 meshing with the gear 242 is slidably arranged at the lower side of the mounting groove 241. A first spring 244 is arranged between the front side of the rack 243 and the mounting groove 241. A push rod 245 is connected to the rear side of the rack 243. A semicircular boss 26 matching the push rod 245 is fixed to the lower side of the circular shell 2.

[0035] The fixed semicircular bar 251 and the movable semicircular bar 252 together form a circular column with a gap therebetween. A cutter 253 is fixed to the inner side of the movable semicircular bar 252. The fixed semicircular bar 251 is provided with a knife groove 254 matching the cutter 253. A clamping assembly is provided on one side of the movable semicircular bar 252.

[0036] In the initial state, the two groups of winding rollers 25 are in a horizontal state. At this time, the fixed semicircular bar 251 and the movable semicircular bar 252 together form a circular column. The working principle of the winding assembly is as follows: when the first motor 22 is started to drive the circular plate 21 to rotate clockwise, the winding roller 25 on the right side moves downward, and the push rod 245 will abut against the semicircular boss 26, and the rack 243 will be pushed forward by the push rod 245, which will drive the gear 242 to rotate, so that the movable semicircular bar 252 will flip upward to a vertical state with the fixed semicircular bar 251, and the winding roller 25 continues to move in this state. When the circular plate 21 rotates 180 degrees clockwise, the push rod 245 is out of contact with the boss 26, so that the rack 243 is pushed to reset under the elastic force of the first spring 244, and the movable semicircular bar 252 will flip downward and fit with the fixed semicircular bar 251;

[0037] Three groups of unwinding rollers 13 are arranged longitudinally, the upper and lower unwinding rollers 13 unwind the solder sheet, and the middle unwinding roller 13 unwinds the metal wire. The solder sheet, the metal wire and the solder sheet are stacked in sequence and enter between the two rolling wheels 11 for rolling. The rolled solder is rolled by the winding assembly.

[0038] When the solder end is connected to the left winding roller 25 for the first time, the circular plate is controlled by the first motor 22 to make the top rod 245 of the left winding roller 25 abut against the left end of the semicircular boss 26. At this time, the movable semicircular bar 252 and the fixed semicircular bar 251 are perpendicular to each other. The staff places the solder end on the left side of the fixed semicircular bar 251, and then starts the first motor 22 to drive the circular plate 21 to rotate clockwise for a short distance so that the two winding rollers 25 are in a horizontal state. At this time, the top rod 245 is out of contact with the semicircular boss 26, and the movable semicircular bar 252 flips downward to tightly press the solder end through the clamping assembly, and then the second motor 23 drives the winding roller 25 to rotate to wind the solder;

[0039] When the winding amount of the left winding roller 25 is about to reach the standard, the first motor 22 is started to drive the circular plate 21 to rotate clockwise, and the left winding roller 25 continues to wind the solder until the right winding roller 25 moves to the left. At this time, the top rod 245 is out of contact with the semicircular boss 26, and the movable semicircular bar 252 moves downward to fix the left side of the solder through the clamping assembly, and the cutter 253 in the middle of the movable semicircular bar 252 moves downward to the knife groove 254 to cut off the solder. The second motor 23 drives the winding roller 25 to rotate, and the solder can continue to be wound. The two winding rollers 25 are automatically handed over and wound, and there is no need to stop, which greatly improves the working efficiency of the device.

[0040] The clamping assembly includes a sliding groove 3 formed by a movable semicircular bar 252, in which a sliding bar 31 is slidably provided, a second spring 32 is provided between the sliding bar 31 and the side wall of the movable groove 3, and a pressing plate 33 abutting against the fixed semicircular bar 251 is provided at the end of the sliding bar 31; when the movable semicircular bar 252 moves downward, the pressing plate 33 will first contact the solder, so that the second spring 32 is compressed, so that when the movable semicircular bar 252 and the fixed semicircular bar 251 form a circular column, the end of the solder can be fixed by the pressing plate 33, and the solder can be rolled up when the winding roller 25 rotates.

[0041] A connecting shaft 4 is fixed to the end of the circular seat 24 , a connecting seat 41 is fixed to the connecting shaft 4 , a mounting shell 42 matching the connecting seat 41 is fixed to the output shaft of the second motor 23 , and a connecting component is provided between the connecting seat 41 and the mounting shell 42 .

[0042] The connecting component includes a slide groove 411 provided on the connecting seat 41, a locking block 412 is slidably provided in the slide groove 411, a locking groove 421 matching the locking block 412 of the mounting shell 42, a third spring 413 is provided between the locking block 412 and the slide groove 411, a movable groove 43 is provided in the middle of the connecting shaft 4, a movable block 44 is slidably provided in the movable groove 43, the movable block 44 is connected to the locking block 412 through a first pull wire 45, a first handle 46 is provided at the front end of the fixed semicircular bar 251, the first handle 46 is connected to the movable block 44 through a second pull wire 47, and a second handle 48 located outside the first handle 46 is also fixed to the front end of the fixed semicircular bar 251.

[0043] The locking block 412 can be pushed into the locking groove 421 by the elastic force of the third spring 413, so that the connecting seat 41 and the mounting shell 42 can be fixed to each other, and the output shaft of the second motor 23 can drive the winding roller 25 to rotate;

[0044] When the winding roller 25 is full of solder, it needs to be replaced. The staff member holds the winding roller 25 as a whole with one hand and holds the second handle 48 with the other hand. At the same time, he uses four fingers to pull the first handle 46 forward, and drives the movable block 44 to slide in the movable groove 43 through the second pull wire 46. The locking block 412 is driven by the first pull wire 45 to leave the locking groove 421 and retract into the slide groove 411. The connection seat 41 and the mounting shell 42 are released. The staff member only needs to slide forward to remove the winding roller 25 as a whole, so the operation of replacing the winding roller 25 is very simple.

[0045] The present invention relates to combining two solder sheets with a metal wire, rolling the metal wire into a filling solder by a roller, and forming a final flat solder by repeated rolling. In order to ensure that the integrated solder has excellent flatness and bonding strength, the total thickness of the filling solder should be more than four times the thickness of the integrated solder, and the thickness of the metal wire should be more than three times the thickness of the integrated solder;

[0046] The diameter of the metal wire is set to 30% to 95% of the thickness of the two pieces of filler solder 6, more preferably 50% to 85%;

[0047] In order to obtain better bonding strength, the oxide layer on the surface of the filler solder and the metal wire needs to be removed before rolling;

[0048] If the selected metal wire is easy to oxidize, such as copper (Cu), a metal layer of the same material as the base material of the filler solder can be plated on the surface of the metal wire. For example, if the metal wire is copper and the filler solder is tin-silver alloy (SnAg3.5), tin (Sn) can be plated on the copper surface to prevent oxidation of the copper surface and form a better bonding force with the filler solder during the rolling process;

[0049] In order to prevent the wire from deviating from the molten solder during welding, the metal wire needs to be greater than 0.5mm from the solder boundary. At the same time, in order to ensure good capillary action and exhaust effect, the distance between two adjacent metal wires needs to be greater than 0.5mm.

[0050] After welding, the integrated solder can maintain the wettability and void rate of the filling solder. At the same time, due to the high melting point of the filling material, it can provide good support during welding;

[0051] The solder sheet is mainly a commonly used soft solder material, including Sn-based solder, Pb-based solder, In-based solder, Bi-based solder, Zn-based solder, Cd-based solder, Ga-based solder, and pure metals of these materials can also be used, such as Sn, Pb, In, Bi, Zn, Cd, Ga, etc.;

[0052] Example

[0053] In this embodiment, we selected SnAg3.5 as the filler solder, with a thickness of 0.5 mm and a width of 70 mm. The metal wire material is oxygen-free copper with a diameter of 0.8 mm, and a 25 μm thick Sn shell is plated on its surface to prevent oxidation of the Cu layer.

[0054] Next, we use a brushing process to remove the oxide layer from the surface of the filler solder and metal wire;

[0055] Then, two sheets of SnAg3.5 filler solder were aligned and placed in a rolling mill. A short section was first rolled to check the alignment. Then, the metal wire was inserted into the filler solder in parallel and the overall thickness was rolled to 0.4 mm. The thickness was then reduced to 0.2 mm through two more rollings.

[0056] Further, a welding piece with a length and width of 20*20 mm is formed by stamping;

[0057] The chip is soldered using an integrated soldering pad and placed in a formic acid furnace for soldering. The formic acid furnace used is a JFHK-HJL / 100 device produced by Beijing Jingfu Huakong Electronic Equipment Co., Ltd.

[0058] First, the formic acid furnace was evacuated to 1 mbar and maintained for 30 seconds, and then filled with nitrogen at a rate of 50 L / min until the pressure reached 1000 mbar and maintained for 2 seconds; then, it was evacuated again to 1 mbar and maintained for 2 seconds, and then filled with nitrogen again to 1000 mbar at a rate of 50 L / min and maintained for 2 seconds. Through these two steps of evacuating and filling with nitrogen, the oxygen content in the chamber was significantly reduced;

[0059] Next, the temperature is quickly raised to 180°C at a rate of 2°C / s, and vacuuming is started. After the temperature reaches 1mbar, formic acid is filled in. The formic acid is introduced through nitrogen at a rate of 8L / min. When the vacuum degree in the chamber reaches 600mbar, nitrogen is filled in to raise the vacuum degree to 1000mbar at a rate of 50L / min. Then the temperature in the furnace is slowly raised to 220°C at a rate of 4°C / min. By slowly heating, the surface temperature of the welding material is ensured to be uniform, and the formic acid can more effectively reduce the surface oxide layer under the action of temperature and time.

[0060] Next, the temperature in the furnace was quickly raised to 250°C and maintained for 30 seconds. The chamber was then evacuated to 1 mbar and nitrogen was introduced again to 1000 mbar. The pressure was maintained for 20 seconds and then quickly cooled to room temperature.

[0061] Figure 8The SAT graph after soldering is shown, and it can be observed that there is no poor wetting or voiding, which is consistent with the performance of conventional SnAg3.5 solder, indicating that it has good soldering performance;

[0062] Fig. 9 This is a cross-sectional picture after welding. It can be clearly seen that an IMC layer is formed between the filler solder and the metal wire, which is the key to ensuring good mechanical properties and cycle reliability.

[0063] According to the power cycle test conducted according to ECPE Guideline 324 (AQG 324), the constant load current of each IGBT is about 250A, the junction temperature difference ΔTj = 100K, the turn-on time ton = 3s, the cooling time toff = 6s, the gate voltage VGE = 15V, and the temperature range is from Tmin = 40℃ to Tmax = 140℃; conventional SnAg3.5 solder will have voids after 1000 cycles and basically fail after more than 3000 cycles. However, Fig.10 It can be seen that the solder of the present invention still maintains good bonding strength after 30,000 cycles.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A rolling device for adding metal wire to solder, comprising a frame, a rolling wheel is arranged in the middle of the frame, and three sets of unwinding rollers are arranged on the left side of the frame, characterized in that: A winding assembly is arranged on the right side of the frame, and the winding assembly comprises a circular shell fixed on the frame, a circular plate is rotatably mounted on the front side of the circular shell, a first motor is mounted on the middle part of the circular shell, an output shaft of the first motor is connected to the circular plate, a second motor is mounted on both sides of the left and right sides of the circular plate, a circular seat is mounted on the output shaft of the second motor, and a winding roller is mounted on the front side of the circular seat; The winding roller is composed of a fixed semicircular bar and a movable semicircular bar, the fixed semicircular bar is fixedly connected to the circular seat, the circular seat is provided with a mounting groove, a gear is rotatably mounted in the mounting groove, the rear end of the movable semicircular bar is connected to the gear, a rack meshing with the gear is slidably arranged on the lower side of the mounting groove, a first spring is arranged between the front side of the rack and the mounting groove, a push rod is connected to the rear side of the rack, and a semicircular boss matching the push rod is fixed on the lower side of the circular shell; The fixed semicircular bar and the movable semicircular bar together form a circular column with a gap therebetween. A cutter is fixed on the inner side of the movable semicircular bar. A knife groove matching the cutter is provided on the fixed semicircular bar. A clamping assembly is provided on one side of the movable semicircular bar.

2. A rolling device for adding metal wire to solder according to claim 1, characterized in that: The clamping assembly includes a sliding groove opened by the movable semicircular bar, a sliding bar is slidably arranged in the sliding groove, a second spring is arranged between the sliding bar and the side wall of the movable groove, and a pressing plate abutting against the fixed semicircular bar is arranged at the end of the sliding bar.

3. A rolling device for adding metal wire to solder according to claim 2, characterized in that: A connecting shaft is fixed to the end of the circular seat, a connecting seat is fixed to the connecting shaft, a mounting shell matching the connecting seat is fixed to the output shaft of the second motor, and a connecting component is provided between the connecting seat and the mounting shell.

4. A rolling device for adding metal wire to solder according to claim 3, characterized in that: The connecting assembly includes a slide groove provided on the connecting seat, a locking block slidingly arranged in the slide groove, a locking groove matching the locking block in the mounting shell, a third spring provided between the locking block and the slide groove, a movable groove provided in the middle of the connecting shaft, a movable block slidingly arranged in the movable groove, the movable block being connected to the locking block via a first pull wire, a first handle being provided at the front end of the fixed semicircular bar, the first handle being connected to the movable block via a second pull wire, and a second handle located outside the first handle being also fixed at the front end of the fixed semicircular bar.

5. A rolling method for a rolling device with a metal wire added to solder according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: The three groups of unwinding rollers are respectively placed with solder sheets, metal wires and solder sheets, and stacked in the order of solder sheets, metal wires and solder sheets; Step 2: Start the rolling wheel set on the frame, roll the stacked solder sheets and metal wires through the rolling wheel, and roll the processed solder through the winding assembly; Step 3: When the winding amount of the left winding roller is about to reach the standard, start the first motor to drive the circular plate to rotate clockwise, and the left winding roller continues to wind the solder until the right winding roller moves to the left side. The movable semicircular bar of the winding roller moves downward, and the left side of the solder is fixed by the clamping assembly. At the same time, the cutter in the middle of the movable semicircular bar moves downward into the knife groove to cut off the solder, so that the winding roller can continue to wind the solder, realizing automatic handover and winding without stopping.

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