Positioning clamp for prefabricating gold-plated cover plate solder and prefabricating method thereof

Abstract

The invention discloses a positioning clamp for prefabricating a gold-plated cover plate solder and a prefabricating method thereof.The positioning clamp is arranged on a lower electrode and comprises at least two fixed right-angle positioning blocks fixed to the lower electrode; the floating mechanism is arranged along a diagonal line of the fixed right-angle positioning block in an extending mode, a same-polarity magnet is arranged in the floating mechanism, and the floating mechanism is further connected with a movable sliding block fixing plate; and the limiting mechanism limits the moving path of the sliding block fixing plate, pokes the sliding block fixing plate, and can drive the floating mechanism to move axially under the acting force of repulsion of the magnets with the same polarity so as to correct the cover plate and the solder piece. Welding spots on the upper surface of the welding flux piece are smooth and round, free of chromatic aberration oxidation and located at the center of the four corners of the welding flux ring by + / -0.05 mm; the attaching gap between the solder sheet and the gold-plated cover plate is controlled within 0.05 mm; the relative offset size of the solder piece and the gold-plated cover plate is controlled within 0.02 mm, and the quality of prefabricating the solder of the gold-plated cover plate is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of gold-plated cover plate solder prefabrication for integrated circuits, and in particular to a positioning fixture for gold-plated cover plate solder prefabrication and a prefabrication method thereof. Background Art

[0002] Gold-plated cover plays a vital role in the packaging of electronic components such as microwave integrated components, T / R components, MEMS devices, optoelectronic devices, etc.

[0003] The traditional production process of gold-plated cover plates and solder involves separate manufacturing, precise alignment, connection, and positioning through molds to ensure a perfect fit between the base, solder, and cover plate. This process is not only cumbersome, but also inefficient. In contrast, the use of solder prefabrication process to weld the gold-plated cover plate and solder as a whole can significantly improve the speed, solderability, reliability, and production efficiency of the lid package.

[0004] In the solder prefabrication process, laser welding or resistance welding technology is usually used, as described below:

[0005] Laser welding uses a focused laser beam as a heat source to generate heat by bombarding the solder sheet to achieve welding. However, laser welding may cause breakdown and damage to the gold-plated cover for solder sheets with a thickness of ≤0.05mm, thereby destroying the product's sealing and salt spray resistance.

[0006] Resistance welding heats the weldment to a molten or plastic state by generating resistance heat when current flows through the weldment and its contact points, and completes welding under pressure, so that the solder and the gold-plated cover are tightly bonded. However, in traditional resistance welding, the electrode end surface is flat, the contact with the solder is not solid, and some parts are suspended in the air, resulting in uneven discharge force, which may cause problems such as excessive melting, breakdown and oxidation.

[0007] In order to solve these problems, both of the above welding methods use external positioning molds and pressure plates as fixtures. The external positioning mold is used to relatively position the solder sheet and the cover plate, while the pressure plate is used to fit the solder sheet and the cover plate tightly to prevent the solder sheet from arching due to offset and stress release during the welding process. However, the positioning groove size of the traditional external positioning mold is fixed, and it is affected by the material processing error, the tolerance of the fixture itself, and the assembly error. It is difficult to ensure that the cover plate and the solder sheet can be easily assembled into the mold and avoid relative offset. The offset of the solder sheet will cause problems such as solder overflow and over-flow during welding. In addition, in order to improve efficiency, multiple products are usually placed in the fixture at one time, but due to the product thickness tolerance and the pressure block processing error, the pressure plate cannot contact all products at the same time and press the solder and cover plate, resulting in the uncontacted products. The solder sheet arches and does not fit during prefabrication, and then when the customer seals the cap, there will be problems such as cold soldering, non-wetting, and product leakage.

[0008] In summary, the traditional solder prefabrication method has many problems, such as excessive melting, breakdown, oxidation of solder joints; the solder sheet and the gold-plated cover plate do not fit together, the solder arches; and the solder sheet and the gold-plated cover plate are relatively offset, etc. Therefore, an improved gold-plated cover plate solder prefabrication method is urgently needed to solve the quality problems in traditional solder prefabrication. Summary of the invention

[0009] The technical problem to be solved by the present invention is how to achieve a gold-plated cover plate surface without dirt or marks, a smooth and round welding surface and solder adhesion without deviation during the solder prefabrication process.

[0010] In order to solve the above technical problems, the present invention provides a positioning fixture for prefabrication of gold-plated cover solder, which is arranged on the lower electrode and includes:

[0011] A fixed right-angle positioning block, which is fixed to the lower electrode and at least two are provided;

[0012] A floating mechanism is provided along a diagonal line of the fixed right-angle positioning block, the floating mechanism has a same-sex magnet built in, and the floating mechanism is also connected to a movable slider fixing plate; and

[0013] The limiting mechanism limits the moving path of the slider fixing plate, moves the slider fixing plate, and can drive the floating mechanism to axially move under the repulsive force of like-sex magnets to correct the cover plate and the solder sheet.

[0014] Furthermore, the floating mechanism includes a floating right-angle positioning block and a sliding block arranged at right angles to each other; the floating right-angle positioning block extends from the center of the fixed right-angle positioning block along a diagonal of the fixed right-angle positioning block, and the fixed right-angle positioning block and the floating right-angle positioning block are clamped to each other.

[0015] Furthermore, the floating right-angle positioning block is made of plastic; and the sliding block is made of stainless iron.

[0016] Furthermore, a first magnet is provided on the contact surface between the floating right-angle positioning block and the slider; a second magnet is provided on the end of the slider away from the slider fixing plate, and the second magnet and the first magnet are magnets of the same polarity that repel each other.

[0017] Furthermore, the contact surface between the slider and the slider fixing plate is an inclined surface.

[0018] Furthermore, the limiting mechanism includes a plurality of groups of positioning pins and limiting holes that cooperate with each other, wherein:

[0019] The positioning pin is arranged at the corner of the slider fixing plate;

[0020] The limiting hole is arranged through the fixed pressing plate, and the fixed pressing plate covers the slider fixing plate.

[0021] A second aspect of the present invention provides a method for prefabricating solder for a gold-plated cover plate, using the positioning fixture for prefabricating solder for a gold-plated cover plate, and the method comprises the following steps:

[0022] S1. Pretreatment: pretreatment of the upper electrode and the lower electrode respectively;

[0023] S2, mounting and positioning: assembling the cover plate and the solder sheet into the positioning fixture, and correcting the cover plate and the solder sheet by positioning the fixture to control the relative offset between the cover plate and the solder sheet within 0.02 mm; capturing the center point coordinates of the cover plate by camera positioning to ensure that the solder point is located at the center of the solder sheet;

[0024] S3, pre-welding operation: the upper electrode pre-presses the solder sheet, and the welding current slowly increases to a set value within a set time, so that the electrode contacts the solder from point to surface, and the solder melts from point to surface until it has the same spherical shape as the upper electrode end surface.

[0025] Further, the S1 includes:

[0026] Grinding the end surface of the upper electrode to obtain a mirror spherical end surface;

[0027] The surface of the lower electrode plate is sandblasted to increase the contact points between the cover plate and the lower electrode.

[0028] Furthermore, the S3 also includes:

[0029] S31, pre-pressing: the upper electrode slowly approaches the solder sheet until the pressure reaches a set value and is maintained for 0-100ms to keep the stage pressure constant;

[0030] S32, current slow increase: the welding current is slowly increased linearly from 10-900A within a set time of 0-100ms, so that the solder sheet is slowly melted at a local position;

[0031] S33, current discharge: when the welding current slowly rises to the set value, the welding current is constantly discharged within 0-100ms;

[0032] S34, cooling: the welding temperature slowly decreases with the welding current within 0-100ms, so that the welding position of the solder sheet is gradually solidified;

[0033] S35, pre-welding forming: the welding points of the single solder sheet are welded in sequence according to an N-type route.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention provides a gold-plated cover plate solder prefabrication method and a positioning fixture and welding parameter range used therein, so as to achieve smooth and round solder joints on the upper surface of a solder sheet without color difference oxidation, and the solder joints are located at the centers of the four corners of a solder ring by ±0.05 mm; the gap between the solder sheet and the gold-plated cover plate is controlled within 0.05 mm; the relative offset size between the solder sheet and the gold-plated cover plate is controlled within 0.02 mm, thereby significantly improving the quality of solder prefabrication of the gold-plated cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the surface state of the lower electrode disclosed in an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of the shape of the upper electrode end surface disclosed in an embodiment of the present invention;

[0038] Figure 3 It is a structural schematic diagram of a positioning fixture disclosed in an embodiment of the present invention;

[0039] Figure 4 It is a schematic diagram of the structure of the floating mechanism in the positioning fixture disclosed in the embodiment of the present invention;

[0040] Figure 5 It is a schematic diagram of the structure of the die pressing disclosed in the embodiment of the present invention;

[0041] Figure 6 It is a schematic diagram of the melting state of the solder joint disclosed in the embodiment of the present invention.

[0042] In the figure:

[0043] 000, product; 001, cover plate; 002, solder sheet; 003, rubber pressing film; 004, upper pressing plate;

[0044] 100, lower electrode;

[0045] 110. Fix the right angle positioning block;

[0046] 121, floating right-angle positioning block; 121a, first magnet; 122, slider; 122a, second magnet; 123, slider fixing plate; 123a, positioning pin;

[0047] 200, fixed pressure plate; 210, limiting hole;

[0048] 300. Tablet pressing. DETAILED DESCRIPTION

[0049] In order to make the technical scheme and technical effect of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0050] The present invention aims to provide a positioning fixture for prefabrication of solder of a gold-plated cover plate and a prefabrication method thereof, so as to achieve a clean and trace-free surface of the cover plate, a smooth and rounded welding surface, and solder lamination without deviation.

[0051] The first aspect of the present invention discloses a positioning fixture for prefabrication of solder for gold-plated cover plates, see Figure 3 , the positioning fixture is arranged on the lower electrode 100, and mainly includes a fixed right-angle positioning block 110, a floating mechanism and a limiting mechanism. Among them, the fixed right-angle positioning block 110 is fixed to the lower electrode 100, and at least two are provided. In one embodiment, the fixed right-angle positioning block 110 is a square structure and four are symmetrically provided on the lower electrode 100. A floating mechanism is provided along a diagonal line of the fixed right-angle positioning block 110, and the floating mechanism is equipped with a same-sex magnet. The floating mechanism is also connected to a movable slider fixing plate 123. The limiting mechanism limits the moving path of the slider fixing plate 123. When the slider fixing plate 123 is manually moved, the floating mechanism can be driven to axially displace under the repulsive force of the same-sex magnets to correct the cover plate 001 and the solder sheet 002.

[0052] First, the floating mechanism in the present invention will be described.

[0053] See also Figure 4 The floating mechanism includes a floating right-angle positioning block 121 and a slider 122 arranged at right angles to each other. The floating right-angle positioning block 121 is extended from the center of the fixed right-angle positioning block 110 along a diagonal line of the fixed right-angle positioning block 110, and the fixed right-angle positioning block 110 and the floating right-angle positioning block 121 are clamped to each other. The contact surface between the slider 122 and the slider fixing plate 123 is an inclined surface.

[0054] In a further solution, the floating right angle positioning block 121 is made of plastic material; the sliding block 122 is made of stainless steel. Optionally, the floating right angle positioning block 121 is made of POM; the sliding block 122 is made of stainless steel 430.

[0055] A first magnet 121 a is disposed on the contact surface between the floating right-angle positioning block 121 and the slider 122 .

[0056] The end of the slider 122 away from the slider fixing plate 123 is provided with a second magnet 122a, and the second magnet 122a and the first magnet 121a are magnets of the same polarity that repel each other. In one embodiment, the first magnet 121a and the second magnet 122a are both N-pole magnets.

[0057] A person skilled in the art may further explain that, in the initial state, the slider 122 can fit with the end face of the floating right-angle positioning block 121 through the first magnet 121a due to its stainless iron material; when the slider fixing plate 123 is moved, the slider 122 can be axially displaced along the contact surface with the floating right-angle positioning block 121; when the second magnet 122a at the end of the slider 122 approaches the first magnet 121a, due to the repulsive force of the two magnets, the floating right-angle positioning block 121 is pushed to displace along the diagonal of the fixed right-angle positioning block 110, thereby correcting the relative offset between the cover plate 001 and the solder sheet 002.

[0058] In a further solution, the limiting mechanism includes a plurality of groups of mutually cooperating positioning pins 123a and limiting holes 210, wherein the positioning pins 123a are arranged at the corners of the slider fixing plate 123; the limiting holes 210 are arranged through the fixed pressure plate 200, and the fixed pressure plate 200 covers the slider fixing plate 123. The limiting mechanism is used to limit the moving path of the slider fixing plate 123.

[0059] The second aspect of the present invention discloses a method for prefabricating solder for a gold-plated cover plate.

[0060] S1. Preprocessing

[0061] S11 , lower electrode pretreatment: performing sandblasting on the surface of the lower electrode plate to increase the contact points between the cover plate 001 and the lower electrode 100 .

[0062] In the scheme disclosed in this embodiment, the surface of the lower electrode plate is sandblasted, and the surface roughness of the lower electrode is 0.8-3.2. 40-300 mesh glass round sand is used for sandblasting at 0.05-0.5MPa, and spiral sandblasting is performed 2-10 times. When it becomes frosted, ultrasonic degreasing, cleaning and drying are used.

[0063] In a further scheme, the lower electrode material is chromium zirconium copper, with a hardness of 122HB and a conductivity of 75% IACS. It has high hardness, long life, excellent conductivity and stable welding. The lower electrode roughness is 0.8-3.2 and ultrasonic degreasing and cleaning are used to ensure that there are no protrusions on the surface of the lower electrode plate, and impurities chrome damage the gold-plated cover plate. When sandblasting is performed, the surface of the lower electrode is a uniform fine particle unit of 0.05-0.4mm in size, which increases the contact points between the gold-plated cover plate and the lower electrode, such as Figure 1 As shown, bright marks are avoided due to uneven contact between the gold-plated cover plate and the lower electrode plate.

[0064] S12, upper electrode pretreatment: grinding the end surface of the upper electrode to obtain a mirror spherical end surface.

[0065] In the scheme disclosed in this embodiment, the upper electrode end surface is polished. The upper electrode has a diameter of 3 mm and is clamped using a pistol drill. It is polished on the surface of 3W-20W metallographic sandpaper at a speed of 500-1500 rpm. During polishing, the upper electrode and the metallographic sandpaper are swung left and right within a range of 45-90° for 2-10 times.

[0066] In a further solution, the upper electrode material is CuW50-CuW85, with a hardness of 115HB-240HB and a conductivity of 55-31% IACS. It has high hardness, long life, and good conductivity. After polishing, it is a 1 / 3-1 / 6 mirror spherical shape, such as Figure 2 As shown, the shape of the solder after melting is the same as the mirror spherical shape of the upper electrode.

[0067] S13. Wipe: Wipe the tools such as clamps, electrodes, tweezers, and traceless suction cups with alcohol. Dip medical cotton wool in alcohol (concentration 60%-90%). The alcohol concentration should not be too low, otherwise residual moisture will remain on the surface of the tool to contaminate the product. Let it dry for 3-5 minutes.

[0068] S2. Mounting and positioning

[0069] S21. Use a non-marking suction cup to assemble the cover plate and the solder sheet into the positioning fixture. The gap between the positioning groove and the product is 0.1-0.3mm. Use tweezers to grab the solder sheet and place it on the upper surface of the cover plate to pre-position the relative position of the cover plate and the solder sheet.

[0070] S22. After assembling the cover plate and the solder sheet into the positioning fixture, the cover plate and the solder sheet are aligningly processed by the fixture positioning to control the relative offset between the cover plate and the solder sheet within 0.02mm. The upper pressure plate floats in contact and presses the solder sheet to ensure that the solder sheet fits the cover plate. The center point coordinates of the cover plate are captured by camera positioning to ensure that the solder point is located at the center of the solder sheet.

[0071] In the solution disclosed in this embodiment, the product in the positioning groove is photographed (500-1500w pixels), the center coordinates of the cover plate are captured, and the position from the center of the product to the center of the four corners of the solder ring is calculated. The camera repeatability accuracy is ±0.01mm, and the positioning accuracy of the servo motion mechanism is ±0.02mm. Camera positioning can compensate for the relative position error between the fixture grooves of the entire board.

[0072] In a further solution, the upper pressure plate is composed of a pressure sheet and a rubber pressure mold. The pressure sheet is 0.2-0.7mm stainless steel 430, which has certain flexibility and rigidity. The rubber pressure mold is 5160 silicone rubber with a Shore hardness of 50-70A. 10-30 magnets are set on the surface of the fixture to provide uniform suction, such as Figure 5 As shown, the adsorption pressing sheet drives the silicone rubber to press each solder sheet and the cover plate tightly together.

[0073] S3. Pre-welding operation

[0074] The upper electrode pre-presses the solder sheet, and the welding current slowly increases to the set value within the set time, so that the electrode and the solder are in contact from point to surface, and the solder melts from point to surface until it has the same spherical shape as the upper electrode end surface. The upper electrode pre-presses the product and the current slowly increases, so that the electrode and the solder are in contact from point to surface during the partial melting of the solder, and the solder also melts from point to surface until it has the same spherical shape as the upper electrode end surface, making the solder joint smoother and rounder, such as Figure 6 As shown. Specifically:

[0075] S31, pre-pressing: the upper electrode slowly approaches the solder sheet until the pressure control box reaches the set value (0.1-0.9kgf), and maintains 0-100ms, keeping the stage pressure constant, and wait for the sensor feedback signal to start the power supply welding.

[0076] S32. Slow current rise: For local welding of the solder sheet, the welding current increases linearly and slowly from 10-900A within the set time of 0-100ms, and the temperature of the contact position between the solder and the electrode increases slowly, causing the local position of the solder sheet to melt slowly.

[0077] S33, current discharge: When the welding current slowly rises to the set value, the welding current is discharged constantly within 0-100ms.

[0078] Those skilled in the art further explained that the welding current should not be set too high or too low. If it is too high, the diameter of the weld point will be too large due to the melting and accumulation of the weld point; if it is too low, the weld sheet and the gold-plated cover plate will not be firmly bonded, or the weld sheet will fall off. According to the thickness of the gold-plated cover plate and the weld sheet of 0.02-0.1mm, the length and width of 2*2-40*40mm, and the side width of the weld sheet of 0.25-3mm, setting 10-900A can control the weld point diameter to 0.1-0.3mm.

[0079] S34, cooling: the welding temperature slowly decreases with the welding current within 0-100ms, so that the welding position of the solder sheet is gradually solidified and the welding stress is gradually released.

[0080] S35, pre-welding forming: the welding points of a single piece of solder are welded in sequence according to the N-type route.

[0081] In the solution disclosed in this embodiment, a single product is welded at four points. The four welding points of a single piece of solder are welded in sequence according to the "N" type route. Compared with the "U" type route, a welding stress release notch can be reserved when welding the fourth point to ensure that the solder sheet does not arch and deform during welding. Depending on the size of the product, the whole plate fixture can hold 6-25 pieces for welding.

[0082] Embodiment 1

[0083] Base material 4J29: thickness is 0.25mm; solder sheet Au80Sn20: thickness is 0.05mm, edge width is 0.8mm.

[0084] 1) Pretreatment of lower electrode: sandblast the surface of the lower electrode plate, the surface roughness of the lower electrode is 3.2, use 40 mesh glass round sand 0.05MPa sandblasting, spiral alternate sandblasting 2 times, frosted, ultrasonic degreasing, cleaning and drying;

[0085] 2) Upper electrode pretreatment: Grind the upper electrode end surface. The upper electrode has a diameter of 3 mm. Use a pistol drill to clamp it and grind it on the surface of 20W metallographic sandpaper at a speed of 500 rpm. During grinding, the upper electrode and the metallographic sandpaper are swung twice within a 45° range.

[0086] 3) Wipe: Wipe the fixture, electrode, tweezers, traceless suction cup and other tools with alcohol. Dip medical cotton wool in alcohol (60% concentration). The alcohol concentration should not be too low, as residual moisture will contaminate the product on the surface of the tool. Let it dry for 5 minutes.

[0087] 4) Mounting: Use a non-marking suction cup to assemble the cover plate and the solder sheet into the positioning fixture. The gap between the positioning groove and the product is 0.1mm. Use tweezers to grab the solder sheet and place it on the upper surface of the cover plate to pre-position the relative position of the cover plate and the solder sheet.

[0088] 5) Fixture positioning: The cover plate and the solder sheet are rectified, a fixed right-angle positioning block and a floating right-angle positioning block are clamped together, the relative offset between the cover plate and the solder sheet is controlled within 0.02mm, and the upper pressing plate is in floating contact and presses the solder sheet to ensure that the solder sheet and the cover plate fit together;

[0089] 6) Camera positioning: Take a picture of the product in the positioning groove (1500w pixels), capture the coordinates of the center point of the cover plate, and calculate the position from the center of the product to the center of the four corners of the solder ring. The camera repeatability accuracy is ±0.01mm, and the positioning accuracy of the servo motion mechanism is ±0.02mm;

[0090] 7) Pre-pressure: The upper electrode slowly approaches the solder sheet until the pressure control box reaches the set value (0.1kgf), maintains 100ms, keeps the stage pressure constant, and waits for the sensor feedback signal to start the power supply welding; the electrode follows

[0091] 8) Slow rise: For local welding of the solder sheet, the current 120A is slowly increased linearly within the set time, the slow rise time is 50ms, the temperature of the contact position between the solder and the electrode slowly increases, and the local position of the solder sheet slowly melts;

[0092] 9) Discharge: When the current slowly rises to the set value, the current is discharged at a constant level, and the discharge time is 30ms, which improves the firmness of the molten bond between the solder sheet and the gold-plated cover plate;

[0093] 10) Cooling: The temperature slowly decreases with the current, the soldering position of the solder piece gradually solidifies, the slow-down time is 5ms, and the welding stress is gradually released;

[0094] 11) Pre-welding: A single product is welded at 4 points. Depending on the size of the product, the whole plate fixture can hold 25 pieces for welding.

[0095] Embodiment 2

[0096] Base material Mo: thickness is 0.15mm; solder sheet Au80Sn20: thickness is 0.05mm, edge width is 0.4mm.

[0097] 1) Pretreatment of lower electrode: sandblast the surface of the lower electrode plate, the surface roughness of the lower electrode is 3.2, use 70 mesh glass round sand 0.1MPa sandblasting, spiral alternate sandblasting 2 times, frosted, ultrasonic degreasing, cleaning and drying;

[0098] 2) Upper electrode pretreatment: Grind the upper electrode end surface. The upper electrode has a diameter of 3 mm. Use a pistol drill to clamp it and grind it on the surface of 15W metallographic sandpaper at a speed of 700 rpm. During grinding, the upper electrode and the metallographic sandpaper are swung within a 60° range for 2 times.

[0099] 3) Wipe: Wipe the fixture, electrode, tweezers, traceless suction cup and other tools with alcohol. Dip medical cotton wool in alcohol (60% concentration). The alcohol concentration should not be too low, as residual moisture will contaminate the product on the surface of the tool. Let it dry for 5 minutes.

[0100] 4) Mounting: Use a non-marking suction cup to assemble the cover plate and the solder sheet into the positioning fixture. The gap between the positioning groove and the product is 0.3mm. Use tweezers to grab the solder sheet and place it on the upper surface of the cover plate to pre-position the relative position of the cover plate and the solder sheet.

[0101] 5) Fixture positioning: The cover plate and the solder sheet are rectified, a fixed right-angle positioning block and a floating right-angle positioning block are clamped together, the relative offset between the cover plate and the solder sheet is controlled within 0.02mm, and the upper pressing plate is in floating contact and presses the solder sheet to ensure that the solder sheet and the cover plate fit together;

[0102] 6) Camera positioning: Take a picture of the product in the positioning groove (1500w pixels), capture the coordinates of the center point of the cover plate, and calculate the position from the center of the product to the center of the four corners of the solder ring. The camera repeatability accuracy is ±0.01mm, and the positioning accuracy of the servo motion mechanism is ±0.02mm;

[0103] 7) Pre-pressure: The upper electrode slowly approaches the solder sheet until the pressure control box reaches the set value (0.8kgf), maintains 100ms, keeps the stage pressure constant, and waits for the sensor feedback signal to start the power supply welding; the electrode follows

[0104] 8) Slow rise: For local welding of the solder sheet, the current 300A is slowly increased linearly within the set time, the slow rise time is 70ms, the temperature of the contact position between the solder and the electrode slowly increases, and the local position of the solder sheet slowly melts;

[0105] 9) Discharge: When the current slowly rises to the set value, the current is discharged at a constant level, and the discharge time is 5ms, which improves the firmness of the molten bond between the solder sheet and the gold-plated cover plate;

[0106] 10) Cooling: The temperature slowly decreases with the current, the soldering position of the solder sheet gradually solidifies, the slow-down time is 40ms, and the welding stress is gradually released;

[0107] 11) Pre-welding: A single product is welded at 4 points. Depending on the size of the product, the whole plate fixture can hold 9 pieces for welding.

[0108] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A positioning fixture for prefabrication of gold-plated cover solder, arranged on the lower electrode (100), characterized in that: include: A fixed right-angle positioning block (110), which is fixed to the lower electrode (100) and at least two of which are provided; A floating mechanism is provided along a diagonal line of the fixed right-angle positioning block (110), the floating mechanism has a same-sex magnet built in the floating mechanism, and the floating mechanism is also connected to a movable slider fixing plate (123); and The limiting mechanism limits the moving path of the slider fixing plate (123), moves the slider fixing plate (123), and can drive the floating mechanism to axially displace under the repulsive force of like-sex magnets to correct the cover plate (001) and the solder sheet (002).

2. The positioning fixture for solder prefabrication of the gold-plated cover plate according to claim 1, characterized in that: The floating mechanism comprises a floating right-angle positioning block (121) and a sliding block (122) which are arranged at right angles to each other; the floating right-angle positioning block (121) is extended from the center of the fixed right-angle positioning block (110) along a diagonal line of the fixed right-angle positioning block (110), and the fixed right-angle positioning block (110) and the floating right-angle positioning block (121) are clamped to each other.

3. The positioning fixture for solder prefabrication of the gold-plated cover plate according to claim 2, characterized in that: The floating right-angle positioning block (121) is made of plastic; and the sliding block (122) is made of stainless iron.

4. The positioning fixture for solder prefabrication of the gold-plated cover plate according to claim 2 or 3, characterized in that: A first magnet (121a) is provided on the contact surface between the floating right-angle positioning block (121) and the slider (122); a second magnet (122a) is provided on the end of the slider (122) away from the slider fixing plate (123); the second magnet (122a) and the first magnet (121a) are magnets of the same polarity that repel each other.

5. The positioning fixture for solder prefabrication of the gold-plated cover plate according to claim 2, characterized in that: The contact surface between the slider (122) and the slider fixing plate (123) is an inclined surface.

6. The positioning fixture for solder prefabrication of the gold-plated cover plate according to claim 1, characterized in that: The limiting mechanism comprises a plurality of groups of mutually cooperating positioning pins (123a) and limiting holes (210), wherein: The positioning pin (123a) is arranged at a corner of the slider fixing plate (123); The limiting hole (210) is arranged through the fixed pressing plate (200), and the fixed pressing plate (200) covers the slider fixing plate (123).

7. A method for prefabricating solder for a gold-plated cover plate, using the positioning fixture for prefabricating solder for a gold-plated cover plate as described in any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1, pretreatment: pretreatment of the upper electrode and the lower electrode (100) respectively; S2, mounting and positioning: assembling the cover plate (001) and the solder sheet (002) into the positioning fixture, and performing a correction process on the cover plate (001) and the solder sheet (002) through the positioning of the fixture, so as to control the relative offset between the cover plate (001) and the solder sheet (002) within 0.02 mm; capturing the coordinates of the center point of the cover plate (001) through camera positioning to ensure that the solder point is located at the center position of the solder sheet (002); S3, pre-welding operation: the upper electrode pre-presses the solder sheet (002), and the welding current is slowly increased to a set value within a set time, so that the electrode contacts the solder from point to surface, and the solder melts from point to surface until it has the same spherical shape as the upper electrode end surface.

8. The method for preparing solder for a gold-plated cover plate according to claim 7, characterized in that: The S1 includes: Grinding the end surface of the upper electrode to obtain a mirror spherical end surface; The surface of the lower electrode plate is sandblasted to increase the contact points between the cover plate (001) and the lower electrode (100).

9. The method for preparing solder for a gold-plated cover plate according to claim 7, characterized in that: The S3 further includes: S31, pre-pressing: the upper electrode slowly approaches the solder sheet (002) until the pressure reaches a set value and is maintained for 0-100ms to keep the stage pressure constant; S32, current slowly rising: the welding current is slowly and linearly increased from 10-900A within a set time of 0-100ms, so that the solder sheet (002) is slowly melted at a local position; S33, current discharge: when the welding current slowly rises to the set value, the welding current is constantly discharged within 0-100ms; S34, cooling: the welding temperature slowly decreases with the welding current within 0-100ms, so that the welding position of the solder sheet (002) is gradually solidified; S35, pre-welding forming: welding points of the single solder sheet (002) are welded in sequence according to an N-type route.

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