Positioning Fixture for Solder Prefabrication of Gold-Plated Cover Plate and Its Prefabrication Method

Abstract

The present invention discloses a positioning fixture for prefabrication of gold-plated cover plate solder and a prefabrication method thereof, which is arranged on the lower electrode and includes a fixed right-angle positioning block, which is fixed to the lower electrode and is provided with at least two; a floating mechanism, which is provided with the floating mechanism along a diagonal line of the fixed right-angle positioning block, the floating mechanism is built with a same-sex magnet, and the floating mechanism is also connected to a movable slider fixing plate; and a limiting mechanism, which limits the moving path of the slider fixing plate, moves the slider fixing plate, and can drive the floating mechanism to axially displace under the repulsive force of the same-sex magnets to correct the cover plate and the solder sheet. The present invention realizes that the solder points on the upper surface of the solder sheet are smooth and round, without color difference oxidation, and the solder points are located at the center of the four corners of the solder ring ±0.05mm; the gap between the solder sheet and the gold-plated cover plate is controlled within 0.05mm; the relative offset size between the solder sheet and the gold-plated cover plate is controlled within 0.02mm, which significantly improves the quality of gold-plated cover plate solder prefabrication.

Description

Technical Field

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

[0002] Gold-plated covers play a crucial role in the packaging of electronic components such as microwave integrated modules, T / R modules, MEMS devices, optoelectronic devices, etc.

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

[0004] During the solder prefabrication process, laser welding or resistance welding techniques are usually adopted, which are described as follows:

[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 ≤ 0.05 mm, thereby destroying the product's sealing performance and salt spray resistance.

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

[0007] To solve these problems, both of the above two welding methods use an external positioning mold and a pressing plate as fixtures. The external positioning mold is used for relative positioning of the solder sheet and the cover, while the pressing plate is used to tightly fit the solder sheet and the cover 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 affected by the material processing error, the fixture's own tolerance, and the assembly error, it is very difficult to ensure that the cover 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 excessive flow during welding. In addition, to improve efficiency, multiple products are usually placed at one time in the fixture. However, due to the product thickness tolerance and the pressing block processing error, the pressing plate cannot contact and press all the products at the same time, resulting in the solder sheet of the non-contact products arching and not fitting during prefabrication, and further causing problems such as false soldering, non-wetting, and product air leakage when the customer caps the cover.

[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 disposed through the fixed pressing plate, and the fixed pressing plate covers the slider fixing plate.

[0021] The second aspect of the present invention provides a method for prefabricating a solder for a gold-plated cover plate, which applies the positioning fixture for prefabricating the solder for the gold-plated cover plate. The method includes the following steps:

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

[0023] S2. Mounting and positioning: Assemble the cover plate and the solder sheet into the positioning fixture, and perform alignment processing on the cover plate and the solder sheet through the positioning of the fixture to control the relative offset between the cover plate and the solder sheet within 0.02 mm; Capture the center point coordinates of the cover plate through camera positioning to ensure that the solder joint is located at the center position of the solder sheet;

[0024] S3. Pre-welding operation: The upper electrode pre-presses the solder sheet, and the welding current slowly rises to a set value within a set time, so that the electrode and the solder contact from point to surface, and the solder melts from point to surface until it is the same as the spherical shape of the end face of the upper electrode.

[0025] Further, the S1 includes:

[0026] Grind the end face of the upper electrode to obtain a mirror spherical end face;

[0027] Perform sandblasting on the surface of the lower electrode plate to increase the contact points between the cover plate and the lower electrode.

[0028] Further, the S3 further includes:

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

[0030] S32. Current slow rise: The welding current slowly rises linearly from 10 - 900 A within a set time of 0 - 100 ms, so that the local position of the solder sheet slowly melts;

[0031] S33. Current discharge: When the welding current slowly rises to the set value, the welding current discharges constantly within 0 - 100 ms;

[0032] S34. Cooling: The welding temperature slowly drops within 0 - 100 ms along with the welding current, so that the welding position of the solder sheet gradually solidifies;

[0033] S35. Pre-welding forming: The welding points of a single solder sheet are welded in the order of the N-type route.

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

[0035] By providing a method for prefabricating solder on a gold-plated cover plate, a positioning fixture applied thereto, a welding parameter range, etc., the present invention enables the solder joints on the upper surface of the solder sheet to be smooth, round, without color difference or oxidation, and the solder joints are located at the center of the four corners of the solder ring ±0.05 mm; the fitting gap between the solder sheet and the gold-plated cover plate is controlled within 0.05 mm; the relative offset dimension between the solder sheet and the gold-plated cover plate is controlled within 0.02 mm, significantly improving the quality of prefabricating solder on the gold-plated cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0037] Figure 2 Schematic diagram of the end face shape of the upper electrode disclosed in an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the structure of the positioning fixture disclosed in an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the structure of the floating mechanism in the positioning fixture disclosed in an embodiment of the present invention;

[0040] Figure 5 Schematic diagram of the structure of the die pressing disclosed in an embodiment of the present invention;

[0041] Figure 6 Schematic diagram of the state of the solder joint melting disclosed in an embodiment of the present invention.

[0042] In the figure:

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

[0044] 100, lower electrode;

[0045] 110, fixed 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 pressing plate; 210, limiting hole;

[0048] 300, pressing piece. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] To make the technical solutions and technical effects of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments. Obviously, the described embodiments are 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 prefabricating solder on a gold-plated cover plate and a prefabrication method thereof, so as to achieve a clean and mark-free surface of the cover plate, a smooth and round welding surface, and no offset of the solder fitting.

[0051] In the first aspect of the present invention, a positioning fixture for prefabricating solder on a gold-plated cover plate is disclosed. Please refer to Figure 3 , this 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 has a square structure and four are symmetrically arranged on the lower electrode 100. A floating mechanism is arranged along a diagonal line of the fixed right-angle positioning block 110. The floating mechanism is internally provided with a same-sex magnet, and the floating mechanism is also connected with a movable slider fixing plate 123. The limiting mechanism restricts the movement path of the slider fixing plate 123. When the slider fixing plate 123 is manually toggled, the floating mechanism can be driven to axially displace under the repulsive force of the same-sex magnet to align the cover plate 001 and the solder sheet 002.

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

[0053] Please refer to Figure 4 , the floating mechanism includes a floating right-angle positioning block 121 and a slider 122 that are arranged at a right angle to each other. The floating right-angle positioning block 121 extends along a diagonal line of the fixed right-angle positioning block 110 from the center 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; the slider 122 is made of non-magnetic stainless iron. Optionally, the floating right-angle positioning block 121 is POM; the slider 122 is non-magnetic stainless iron 430.

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

[0056] A second magnet 122a is arranged at the end of the slider 122 away from the slider fixing plate 123, and the second magnet 122a and the first magnet 121a are magnets with the same sex and repulsive force. In one embodiment, both the first magnet 121a and the second magnet 122a are 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 solution disclosed in this embodiment, the end face of the upper electrode is polished. The diameter of the upper electrode is 3 mm. It is clamped by a pistol drill and polished on the surface of 3W - 20W metallographic sandpaper at a rotational speed of 500 - 1500 revolutions per minute. When polishing, the upper electrode swings left and right within the range of 45 - 90° with the metallographic sandpaper for 2 - 10 times.

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

[0067] S13, Wiping: Wipe tools such as jigs, 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 there will be residual moisture on the tool surface, contaminating the product. Air - dry for 3 - 5 min.

[0068] S2, Mounting and Positioning

[0069] S21, Use a traceless suction cup to assemble the cover plate and the solder sheet into the positioning jig. The gap between the positioning groove and the product is 0.1 - 0.3 mm. Use tweezers to pick up 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 jig, perform a rectifying process on the cover plate and the solder sheet through jig positioning to control the relative offset between the cover plate and the solder sheet within 0.02 mm. The upper pressure plate floats and contacts to press the solder sheet tightly to ensure that the solder sheet fits well with the cover plate. Capture the center point coordinates of the cover plate through camera positioning to ensure that the solder joints are located at the center of the solder sheet.

[0071] In the solution disclosed in this embodiment, take a photo (500 - 1500w pixels) of the product in the positioning groove, capture the center point coordinates of the cover plate, calculate the distance from the center of the product to the center positions of the four corners of the solder ring. The repeated photo - taking accuracy of the camera is ±0.01 mm, and the positioning accuracy of the servo motion mechanism is ±0.02 mm. Camera positioning can compensate for the relative position error between the fixture slots of the whole board.

[0072] In a further solution, the upper pressure plate is composed of a pressing piece and a rubber pressing die. The pressing piece is made of 0.2 - 0.7 mm ferritic stainless steel 430, which has a certain flexibility and rigidity. The rubber pressing die is 5160 silicone rubber with a Shore hardness of 50 - 70A. There are 10 - 30 magnets arranged on the surface of the jig to provide uniform suction force, as Figure 5 shown. The adsorbed pressing piece drives the silicone rubber to press each solder sheet tightly against the cover plate.

[0073] S3, Pre - soldering Operation

[0074] The upper electrode pre-presses the solder sheet, and the welding current slowly rises to the set value within the set time, so that the electrode and the solder contact from point to surface, and the solder melts from point to surface until it is the same as the spherical shape of the upper electrode end face. The pre-pressing of the upper electrode and the slow rise of the current can make the electrode and the solder contact from point to surface during the process of partial melting of the solder, and the solder also melts from point to surface until it is the same as the spherical shape of the upper electrode end face, making the solder joint smoother and rounder, as Figure 6 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 - 0.9 kgf) and remains for 0 - 100 ms. The pressure is kept constant during the holding stage, and the power supply for welding is started when the sensor feedback signal is received.

[0076] S32. Current slow rise: Locally weld the solder sheet. The welding current slowly rises linearly from 10 - 900 A within the set time of 0 - 100 ms, and the temperature at the contact position between the solder and the electrode slowly rises, causing the local position of the solder sheet to slowly melt.

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

[0078] Those skilled in the art further explain that the welding current cannot be set too high or too low. If it is too high, it will cause the solder joint to melt and accumulate, and the diameter of the solder joint will be too large; if it is too low, it will cause problems such as the solder sheet not being firmly combined with the gold-plated cover plate and falling off. According to the thickness of the gold-plated cover plate and the solder sheet of 0.02 - 0.1 mm, the length and width of 2 * 2 - 40 * 40 mm, and the side width of the solder sheet of 0.25 - 3 mm, setting 10 - 900 A can control the diameter of the solder joint within 0.1 - 0.3 mm.

[0079] S34. Cooling: The welding temperature slowly drops within 0 - 100 ms along with the welding current, causing the welded position of the solder sheet to gradually solidify and the welding stress to be gradually released.

[0080] S35. Pre-welding forming: The welding points of a single solder sheet are welded in the order of the N-shaped route.

[0081] In the solution disclosed in this embodiment, four points are welded for a single product. The four welding points of a single solder sheet are welded in the order of the "N" - shaped route. Compared with the "U" - shaped route, when welding the fourth point, more welding stress release notches can be reserved to ensure that the solder sheet does not arch and deform during welding. According to the size of the product, 6 - 25 sheets can be placed on the whole - plate fixture for welding.

[0082] Embodiment 1

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

[0084] 1) Lower electrode pretreatment: sandblasting treatment on the surface of the lower electrode plate, surface roughness of the lower electrode is 3.2, sandblasting with 40-mesh glass round sand at 0.05 MPa, sandblasting in a spiral alternating pattern for 2 passes, presenting a frosted appearance, ultrasonic degreasing cleaning and drying;

[0085] 2) Upper electrode pretreatment: grinding treatment on the end face of the upper electrode, diameter of the upper electrode is 3 mm, clamped with a pistol drill, grinding on the surface of 20W metallographic sandpaper, rotation speed is 500 revolutions per minute, the upper electrode swings within a range of 45° with the metallographic sandpaper 2 times during grinding;

[0086] 3) Wiping: wiping tools such as jigs, electrodes, tweezers, and traceless suction cups with alcohol, using medical cotton wool to dip alcohol (concentration 60%), the alcohol concentration should not be too low as there will be residual moisture on the tool surface to contaminate the product, air dry for 5 min;

[0087] 4) Mounting: using a traceless suction cup to assemble the cover plate and the solder sheet into the positioning jig, the clearance between the positioning groove and the product is 0.1 mm, using tweezers to pick up the solder sheet and place it on the upper surface of the cover plate, pre-positioning the relative position of the cover plate and the solder sheet;

[0088] 5) Jig positioning: rectifying the cover plate and the solder sheet, clamping each other with a fixed right-angle positioning block and a floating right-angle positioning block, controlling the relative offset of the cover plate and the solder sheet within 0.02 mm, the upper pressure plate floats in contact and presses the solder sheet tightly to ensure the solder sheet is in contact with the cover plate;

[0089] 6) Camera positioning: taking a photo (15 million pixels) of the product in the positioning groove, capturing the center point coordinates of the cover plate, calculating the position from the center of the product to the center of the four corners of the solder ring, the repeated photo-taking accuracy of the camera is ±0.01 mm, and the positioning accuracy of the servo motion mechanism is ±0.02 mm;

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

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

[0092] 9) Discharging: when the current slowly rises to the set value, the current discharges constantly, the discharging time is 30 ms, to improve the firmness of the molten bonding between the solder sheet and the gold-plated cover plate;

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

[0094] 11) Pre-soldering forming: 4 points are welded for each product. According to the size of the product, 25 sheets can be placed on the whole-board fixture for welding.

[0095] Example 2

[0096] Matrix material Mo: The thickness is 0.15 mm; Solder sheet Au80Sn20: The thickness is 0.05 mm, and the edge width is 0.4 mm.

[0097] 1) Lower electrode pretreatment: Sandblasting treatment is carried out on the surface of the lower electrode plate. The surface roughness of the lower electrode is 3.2. Use 70-mesh glass round sand for sandblasting at 0.1 MPa, and sandblast alternately in a spiral for 2 times to make it in a frosted shape, and then perform ultrasonic degreasing cleaning and drying;

[0098] 2) Upper electrode pretreatment: Grind the end face of the upper electrode. The diameter of the upper electrode is 3 mm. Clamp it with a pistol drill and grind it on the surface of 15W metallographic sandpaper at a rotational speed of 700 revolutions per minute. When grinding, the upper electrode swings within a range of 60° with the metallographic sandpaper for 2 times;

[0099] 3) Wiping: Wipe tools such as fixtures, electrodes, tweezers, and traceless suction cups with alcohol. Dip medical cotton wool in alcohol (concentration 60%). The alcohol concentration should not be too low, otherwise there will be residual moisture on the tool surface to contaminate the product, and dry for 5 min;

[0100] 4) Mounting: Use a traceless 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 0.3 mm. Use tweezers to pick up 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: Rectify the cover plate and the solder sheet. A fixed right-angle positioning block and a floating right-angle positioning block clamp each other, and control the relative offset of the cover plate and the solder sheet within 0.02 mm. The upper pressure plate floats and contacts to press the solder sheet to ensure the solder sheet fits with the cover plate;

[0102] 6) Camera positioning: Take a photo (15 million pixels) of the product in the positioning groove, capture the center point coordinates of the cover plate, calculate the position from the center of the product to the centers of the four corners of the solder ring. The repeated photo-taking accuracy of the camera is ±0.01 mm, and the positioning accuracy of the servo motion mechanism is ±0.02 mm;

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

[0104] 8) Slow rise: Locally weld the solder sheet. The current of 300 A linearly and slowly increases within the set time. The slow rise time is 70 ms. The temperature at 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 discharges constantly for 5 ms to improve the firmness of the molten combination between the solder sheet and the gold-plated cover plate.

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

[0107] 11) Pre-welding forming: Weld 4 points for a single product. According to the size of the product, 9 pieces can be placed on the whole-board fixture for welding.

[0108] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A positioning fixture for prefabricating solder of a gold-plated cover plate, which is arranged on a lower electrode (100), and is characterized in that, Comprising: Fixed right-angle positioning blocks (110), which are fixed to the lower electrode (100) and at least two are provided; A floating mechanism, the floating mechanism is arranged to extend along a diagonal line of the fixed right-angle positioning blocks (110), the floating mechanism is internally provided with a same-sex magnet, and the floating mechanism is further connected to a movable slider fixing plate (123); 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) extends 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; and A limiting mechanism, the limiting mechanism includes a plurality of groups of 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 penetrated through a fixed pressing plate (200), and the fixed pressing plate (200) covers the slider fixing plate (123); the moving path of the slider fixing plate (123) is restricted, the slider fixing plate (123) is toggled, and under the repulsive force of the same-sex magnets, the floating mechanism can be driven to axially displace to align the cover plate (001) and the solder sheet (002).

2. The positioning fixture for prefabricating solder of the gold-plated cover plate according to claim 1, characterized in that, The floating right-angle positioning block (121) is made of plastic material; the slider (122) is made of non-ferrous iron material.

3. The positioning fixture for prefabricating solder of the gold-plated cover plate according to claim 1 or 2, characterized in that, A first magnet (121a) is arranged on the contact surface between the floating right-angle positioning block (121) and the slider (122); a second magnet (122a) is arranged at the end of the slider (122) away from the slider fixing plate (123), and the second magnet (122a) and the first magnet (121a) are magnets with the same sex and repelling each other.

4. A method for prefabricating a solder for a gold-plated cover plate, which uses the positioning fixture for prefabricating the solder of the gold-plated cover plate as described in any one of claims 1-3, is characterized in that, The method includes the following steps: S1. Pretreatment: Pretreat the upper electrode and the lower electrode (100) respectively; S2. Mounting and positioning: Assemble the cover plate (001) and the solder sheet (002) into the positioning fixture, and perform alignment processing on the cover plate (001) and the solder sheet (002) through the fixture positioning to control the relative offset between the cover plate (001) and the solder sheet (002) within 0.02 mm; Capture the center point coordinates of the cover plate (001) through camera positioning to ensure that the solder joint 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 slowly rises to a set value within a set time, so that the electrode and the solder are in point-to-surface contact, and the solder melts from point to surface until it is the same as the spherical shape of the end face of the upper electrode.

5. The solder prefabrication method of the gold-plated cover plate according to claim 4, characterized in that, The S1 includes: Grind the end face of the upper electrode to obtain a mirror spherical end face; Perform sandblasting treatment on the surface of the lower electrode to increase the contact points between the cover plate (001) and the lower electrode (100).

6. The solder prefabrication method for the gold-plated cover plate according to claim 4, wherein The S3 further includes: S31. Preloading: The upper electrode slowly approaches the solder sheet (002) until the pressure reaches the set value and is maintained for 0 - 100 ms to keep the stage pressure constant; S32. Current slow increase: The welding current slowly increases linearly from 10 - 900 A within the set time of 0 - 100 ms, causing the local position of the solder sheet (002) to slowly melt; S33. Current discharge: When the welding current slowly increases to the set value, the welding current discharges constantly within 0 - 100 ms; S34. Cooling: The welding temperature slowly decreases within 0 - 100 ms along with the welding current, causing the welded position of the solder sheet (002) to gradually solidify; S35. Pre - welding forming: The welding points of a single solder sheet (002) are welded in sequence according to the N - type route.

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