Regional gold removing device and gold removing method

Abstract

The invention discloses a regional gold removing device and gold removing method, and belongs to the technical field of microelectronic packaging. The regional gold removing device comprises a pressure mechanism, a limiting mechanism and a sealing mechanism; the limiting mechanism acts on a gold removing area on the gold-removed piece, and a gold plating layer is arranged on the surface of the gold removing area; the sealing mechanism is arranged at the bottom of the limiting mechanism and acts on the limiting mechanism through the pressure mechanism, so that the sealing mechanism plays a sealing role, and a gold removing area is isolated from other areas. The limiting mechanism and the gold removing area form an independent material cup; the independent material cup is internally provided with a gold-removing solder, and the gold-removing solder reacts with the gold-plated layer on the gold-removing area in the independent material cup to remove gold. According to the region gold removing device and the gold removing method, the problem of tin-lead solder random diffusion caused by plane region gold removing can be solved, the gold brittleness influence caused by tin-lead alloy welding is reduced, and the product reliability is ensured. The device is thorough in gold removal and simple to operate.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronic packaging technology, and specifically relates to a device and method for removing gold from a region. Background Art

[0002] In microelectronic packaging, when tin-lead solder is used to solder gold-plated layers, gold rapidly dissolves into the solder, forming brittle compounds with the tin in the solder, typically in AuSn4. When the gold content in the solder exceeds 3%, the solder interface presents reliability risks, potentially causing open leads or detachment of the soldered components.

[0003] The aerospace industry stipulates that when using tin-lead solder to solder the gold-plated layer, in order to ensure product quality, the gold must be removed before soldering to avoid gold brittleness which may reduce product reliability.

[0004] When soldering microelectronic packages, common methods include lead terminals and flat surfaces. While the gold removal process for lead terminals is relatively mature, typically performed using a tin pot tinning process, gold removal techniques for flat soldering areas are relatively lacking. Patent CN111112842A utilizes a laser with a wavelength of 300 to 355 nanoseconds to remove gold from flat soldering areas. This removes most of the gold, but not completely, requiring a certain thickness to protect the soldering surface. Furthermore, if the gold-plated layer has minute ripples on the surface, gold may be removed from the peaks while not removed from the valleys. This excess gold can lead to oxidation of the soldering surface, affecting soldering.

[0005] In practice, directly removing gold from planar surfaces is not feasible because gold dissolves rapidly in tin-lead solder. A 1.27-micron thick gold layer can completely dissolve into the tin-lead solder within 2 seconds. This rapid dissolution rate can easily lead to random diffusion of the tin-lead solder, affecting circuit functionality outside the area. Summary of the Invention

[0006] The purpose of the present invention is to address the above-mentioned shortcomings by providing a device and method for regional gold removal. This structure can solve the random diffusion of tin-lead solder that occurs during planar area gold removal, reduce the gold brittleness caused by tin-lead alloy welding, and ensure product reliability. The device removes gold thoroughly and is simple to operate. To achieve the above-mentioned objectives, the present invention provides the following technical solutions:

[0007] A regional gold removal device comprises a pressure mechanism, a limiting mechanism and a sealing mechanism; the limiting mechanism acts on the gold removal area on the gold-removed part, and the surface of the gold removal area is provided with a gold-plated layer; the sealing mechanism is arranged at the bottom of the limiting mechanism, and the pressure mechanism acts on the limiting mechanism so that the sealing mechanism plays a sealing role, thereby isolating the gold removal area from other areas; the limiting mechanism and the gold removal area form an independent material cup; the independent material cup is provided with gold removal solder, and the gold removal solder reacts with the gold-plated layer on the gold removal area in the independent material cup to remove gold.

[0008] Furthermore, the limiting mechanism is a limiter with a circular or polygonal columnar structure; the top surface and the bottom surface of the limiter are penetrated; the bottom surface of the limiter is in sealing contact with the gold removal area to form an independent material cup.

[0009] Furthermore, the pressure mechanism is a handle; the handle is integrally connected to one side of the limiter, and the limiter is sealed and contacted with the gold removal area by applying a force through the handle.

[0010] Furthermore, the bottom of the limiter is grooved; the sealing mechanism is a sealing ring, which is arranged in the groove at the bottom of the limiter; the handle applies pressure to transfer the force to the sealing ring, and the sealing ring cooperates with the limiter to isolate the gold removal area from other areas.

[0011] Furthermore, a number of mounting plates are evenly arranged on the top edge of the limiter; mounting holes are provided on the mounting plates; the pressure mechanism is a fastening screw matching the number of mounting holes; the fastening screw passes through the mounting hole and is connected to the metal part to be removed, and pressure is applied to the limiter by screwing the fastening screw.

[0012] Furthermore, the bottom of the limiter is grooved; the sealing mechanism is a sealing ring, which is arranged in the groove at the bottom of the limiter; screwing the fastening screw applies pressure to transfer the force to the sealing ring, and the sealing ring cooperates with the limiter to isolate the gold removal area from other areas.

[0013] Furthermore, the bottom groove of the limiter is a rectangular groove, a U-shaped groove, a trapezoidal groove or a dovetail groove.

[0014] Furthermore, the sealing ring is made of a high-temperature resistant elastic material, including nitrile rubber, fluororubber or polytetrafluoroethylene.

[0015] A gold removal method for a regional gold removal device, using the regional gold removal device;

[0016] S1: Place the metal-removed part on a hot plate and heat it to a temperature greater than 210 degrees;

[0017] S2: Place the stopper in the gold removal area and apply pressure through the handle. The sealing ring is deformed by the force. The stopper and the sealing ring isolate the gold removal area and form an independent material cup for the gold removal solder.

[0018] S3: Melt the gold-removing solder and flux into the material cup. Under the wetting effect of the flux, the gold-removing solder quickly melts the gold-plated layer.

[0019] S4: Use a desoldering gun to remove the gold solder and flux from the top of the material cup;

[0020] S5: Repeat steps S3 to S4 to perform the second gold removal operation and remove the limiter;

[0021] S6: Remove the metal-removed parts from the hot stage and cool them down, clean off the residual flux, and the area metal removal is completed.

[0022] A gold removal method for a regional gold removal device, using the regional gold removal device;

[0023] S1: Install the stopper on the metal to be removed and tighten the screws. The sealing ring will deform under the force. The stopper and the sealing ring will isolate the gold removal area to form an independent material cup for the gold removal solder.

[0024] S2: Place the gold-removed solder block into the material cup;

[0025] S3: The gold-removed parts are placed in a eutectic furnace and heated to a temperature greater than 210 degrees. The gold-removing solder melts at high temperature and dissolves the gold-plated layer.

[0026] S4: After the eutectic furnace cools down, the metal parts to be removed are taken out and placed on a hot plate with a temperature greater than 210 degrees.

[0027] S5: After the gold-removing solder in the cup is melted, use a desoldering gun to suck away the solder;

[0028] S6: Repeat steps S2 to S5 to achieve the second gold removal operation;

[0029] S7: Remove the metal removal part from the hot stage, and remove the fastening screws and limiters in sequence after the metal removal part cools down. The metal removal operation is completed.

[0030] The beneficial effects of the present invention are:

[0031] This application used a handheld gold removal device and a screw-fastened gold removal device to remove gold from a 2-micron-thick gold plating layer. The gold removal solder used was a tin-lead (Sn63Pb37) alloy with a melting point of 183°C, removed in two steps. The gold residue in the gold removal area was less than 0.5%, and no solder diffusion occurred, demonstrating excellent gold removal results. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a gold removal device used in Example 1 of the present invention;

[0033] Figure 2 This is a schematic structural diagram of a gold removal device used in Example 2 of the present invention;

[0034] Figure 3 Schematic diagram of the sealing mechanism of the present invention;

[0035] In the attached figure: 1. limiter; 2. independent material cup; 3. metal parts to be removed; 4. handle; 5. sealing ring; 6. fastening screw. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0037] Example 1:

[0038] See attached Figure 1 and 3 A device for removing gold from an area includes a pressure mechanism, a limiting mechanism, and a sealing mechanism. The shape of the limiting mechanism is set according to the gold removal area on the metal removal workpiece 3. The limiting mechanism is a limiter 1 with a circular or polygonal columnar structure. In this embodiment, the limiter 1 is a rectangular columnar structure. Figure 1 As shown, the pressure mechanism acts on the limiting mechanism, so that the limiting mechanism is in close contact with the gold-removed part 3, and a sealing mechanism is provided at the bottom of the limiting mechanism to enhance the sealing between the limiter 1 and the gold-removed part 3. The limiter 1 cooperates with the gold-removed part 3 to seal the gold-removed area from other areas. The top and bottom surfaces of the limiter 1 are a through structure, which can cooperate with the gold-removed area to form an independent material cup 2. The bottom of the independent material cup 2 is the gold-removing area. The gold-removing solder is added to the independent material cup 2 to react with the metal layer under high temperature conditions to melt the gold-plated layer, and then the gold-removing solder with the gold-plated layer dissolved is removed by a desoldering gun. The material of the limiter 1 does not react with the gold-removing solder, and the melting point is higher than 200 degrees of the melted gold-removing solder, so as to avoid the limiter 1 from melting when the gold-removing solder is melted at high temperature, thereby causing structural failure and causing the gold-removing solder to extend to other areas. In this embodiment, the pressure mechanism is a handle 4, one end of which is integrally provided with one side of the stopper 1. The operator applies manual pressure to bring the stopper 1 into close contact with the metal workpiece 3. A groove is provided at the bottom of the stopper 1. The groove structure can be set to an existing structural shape of a rectangular groove, a U-shaped groove, a trapezoidal groove or a dovetail groove. The sealing mechanism is specifically a sealing ring 5, which is provided in the groove at the bottom of the stopper 1. Figure 3 As shown, the sealing ring 5 is made of a high-temperature elastic material, including but not limited to nitrile rubber, fluororubber, polytetrafluoroethylene, and the like, with a temperature resistance greater than 250°C. When a worker applies pressure by gripping the handle 4, the sealing ring 5 deforms under the force, isolating the gold removal area and preventing the melted gold removal solder from flowing outside the gold removal area.

[0039] In the gold removal method of this embodiment, the gold-removed part 3 is prepared in advance using silicon-aluminum alloy, nickel-plated with 12 microns and gold-plated with 2 microns. According to the area, shape and peripheral structure of the gold-removed area on the gold-removed part 3, a limiter 1 structure is designed using 304 stainless steel processing. A groove is set at the bottom of the limiter 1 and a sealing ring 5 is installed, and a handle 4 is set as an integral part. When the gold removal operation is required, the gold-removed part 3 is placed on a hot table and heated to above 210 degrees. The operator operates the handle 4 to align the limiter 1 with the gold-removed area and apply pressure. The sealing ring 5 is deformed by the force, and the limiter 1 and the sealing ring 5 isolate the gold-removed area. The limiter 1 and the sealing ring 5 form an independent material cup 2 for the gold-removing solder. The tin-lead Sn63Pb37 alloy with a melting point of 183 degrees with a core flux is selected as The gold removal solder is melted into the independent material cup 2 to a depth of about 2 mm. Under the action of the flux wetting, the tin-lead solder quickly melts the gold plating layer, and the gold removal solder and flux of the molten metal layer are sucked away from the independent material cup 2 through the suction welding gun to complete the first gold removal operation. The tin-lead Sn63Pb37 alloy with a melting point of 183 degrees and the flux of the wire core is repeatedly melted into the independent material cup 2 as the gold removal solder. Under the action of the flux wetting, the tin-lead solder quickly melts the gold plating layer, and the gold removal solder and flux of the molten metal layer are sucked away from the independent material cup 2 through the suction welding gun. After completing the second gold removal operation, the operator removes the handle 4 and the limiter 1, and finally removes the gold-removed part 3 from the hot stage for cooling. The gold-removed part 3 is cleaned with trichloroethylene to clean the residual flux and dry it, and the regional gold removal is completed. The gold removal device and method of this embodiment were used to remove gold from a 2-micron-thick gold-plated layer. The gold removal solder, made of a tin-lead (Sn63Pb37) alloy with a melting point of 183°C, was removed in two steps. The gold residue in the gold-removed area was less than 0.5%, and no solder diffusion occurred, demonstrating excellent gold removal results.

[0040] Example 2:

[0041] See attached Figures 2-3 A device for removing gold from an area includes a pressure mechanism, a limiting mechanism, and a sealing mechanism. The shape of the limiting mechanism is set according to the gold removal area on the metal removal workpiece 3. The limiting mechanism is a limiter 1 with a circular or polygonal columnar structure. In this embodiment, the limiter 1 is a rectangular columnar structure. Figure 2As shown, the pressure mechanism acts on the limiting mechanism, so that the limiting mechanism is in close contact with the gold-removed part 3, and a sealing mechanism is provided at the bottom of the limiting mechanism to enhance the sealing between the limiter 1 and the gold-removed part 3. The limiter 1 cooperates with the gold-removed part 3 to seal the gold-removed area from other areas. The top and bottom surfaces of the limiter 1 are a through structure, which can cooperate with the gold-removed area to form an independent material cup 2. The bottom of the independent material cup 2 is the gold-removing area. The gold-removing solder is added to the independent material cup 2 to react with the metal layer under high temperature conditions to melt the gold-plated layer, and then the gold-removing solder with the gold-plated layer dissolved is removed by a desoldering gun. The material of the limiter 1 does not react with the gold-removing solder, and the melting point is higher than 200 degrees of the melted gold-removing solder, so as to avoid the limiter 1 from melting when the gold-removing solder is melted at high temperature, thereby causing structural failure and causing the gold-removing solder to extend to other areas. The pressure mechanism in this embodiment is a screw fastening structure. Several mounting plates are evenly arranged on the top edge of the limiter 1 and extend outward in all directions. The mounting plates are provided with mounting holes. The pressure mechanism includes a number of fastening screws 6 corresponding to the number of mounting holes. The fastening screws 6 are passed through the corresponding mounting holes and the limiter 1 is pressurized by screwing the fastening screws 6. The fastening screws 6 can act on the metal-removed part 3. It is necessary to set threaded holes at corresponding positions on the metal-removed part 3, or prepare an action plate and set threaded holes on the action plate. The metal-removed part 3 is placed horizontally on the action plate surface. The mounting holes after the limiter 1 is aligned with the metal-removed area are aligned with the threaded holes on the action plate. This can avoid additional processing of the metal-removed part 3. The above two fixing methods can be selected according to specific circumstances. The fastening screws 6 are screws with spring washers to prevent loosening. A groove is provided at the bottom of the limiter 1. The groove structure can be set to the existing structural shape of a rectangular groove, a U-shaped groove, a trapezoidal groove or a dovetail groove. The sealing mechanism is specifically a sealing ring 5, which is set in the groove at the bottom of the limiter 1, as shown in the attached figure. Figure 3 As shown, the sealing ring 5 is made of a high-temperature elastic material, including but not limited to nitrile rubber, fluororubber, and polytetrafluoroethylene, with a temperature resistance greater than 250°C. By tightening the screw 6 and applying pressure, the sealing ring 5 deforms under the force, isolating the gold removal area and preventing the gold removal solder from flowing outside the gold removal area when it melts.

[0042] The gold removal method of this embodiment is to use silicon aluminum alloy to prepare the gold removal part 3 in advance, nickel-plated with 12 microns and gold-plated with 2 microns. According to the area, shape and peripheral structure of the gold removal area on the gold removal part 3, 304 stainless steel is used to process and design the limiter 1 structure. A groove is set at the bottom of the limiter 1 and a sealing ring 5 is installed. A mounting plate and a mounting hole are integrally processed around the limiter 1. At the same time, corresponding threaded holes are processed on the gold removal part 3. When the gold removal operation is required, the limiter 1 is specifically aligned with the removal area. The gold area is then tightened by screws 6 through the mounting holes and threaded holes. The screws are tightened to apply pressure, and the sealing ring 5 is deformed by force. The stopper 1 and the sealing ring 5 isolate the gold removal area. The stopper 1 and the sealing ring 5 form an independent material cup 2 for gold removal solder. A tin-lead Sn63Pb37 alloy block with a core flux and a melting point of 183 degrees is selected as the gold removal solder and placed in the independent material cup 2. Then the overall structure of the gold removal part 3 and the stopper 1 is placed in a eutectic furnace and heated to a temperature greater than 210 degrees. The tin-lead solder block melts at high temperature to a depth of about 2 mm, dissolving the gold-plated layer. After the eutectic furnace cools down, the gold-removed component 3 is taken out and placed on the hot stage. The temperature of the hot stage is greater than 210 degrees. After the tin-lead solder in the material cup is remelted, the solder is sucked away with a desoldering gun to complete the first gold removal operation. Repeat the process again. The tin-lead Sn63Pb37 alloy block with a melting point of 183 degrees and a core flux is placed in an independent material cup 2 as the gold removal solder. Then, the overall structure of the gold-removed component 3 and the stopper 1 is placed in the eutectic furnace. Heating, the temperature is greater than 210 degrees, the tin-lead solder block melts at high temperature, the depth is about 2 mm, and the gold-plated layer is melted. After the eutectic furnace cools down, the gold-plated part 3 is taken out and placed on the hot stage. The temperature of the hot stage is greater than 210 degrees. After the tin-lead solder in the material cup is remelted, the solder is sucked away with a tin suction gun to complete the secondary gold removal operation. Finally, the gold-plated part 3 is removed from the hot stage to cool, the fastening screws 6 and the limiter 1 are removed, and the gold-plated part 3 is cleaned with trichloroethylene to clean the residual flux and dry. The regional gold removal is completed. By using the regional gold removal device and gold removal method of this embodiment, the 2-micron thick gold-plated layer is regionally gold-removed. The gold removal solder uses a tin-lead Sn63Pb37 alloy with a melting point of 183 degrees, which is removed in two times. The gold residue in the gold removal area is less than 0.5%, no solder diffusion phenomenon occurs, and the gold removal effect is good.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A device for removing gold from a region, characterized by: The invention comprises a pressure mechanism, a limiting mechanism and a sealing mechanism; the limiting mechanism acts on a gold-removed area on a gold-removed part (3), and a gold-plated layer is provided on the surface of the gold-removed area; the sealing mechanism is arranged at the bottom of the limiting mechanism, and the pressure mechanism acts on the limiting mechanism so that the sealing mechanism plays a sealing role and isolates the gold-removed area from other areas; the limiting mechanism and the gold-removed area form an independent material cup (2); the independent material cup (2) is provided with gold-removing solder, and the gold-removing solder reacts with the gold-plated layer on the gold-removed area in the independent material cup (2) to remove gold.

2. The device for removing gold from a region according to claim 1, characterized in that: The limiting mechanism is a limiter (1) with a circular or polygonal columnar structure; the top surface and bottom surface of the limiter (1) are penetrated; the bottom surface of the limiter (1) is in sealed contact with the gold removal area to form an independent material cup (2).

3. The device for removing gold from a region according to claim 2, characterized in that: The pressure mechanism is a handle (4); the handle (4) is integrally connected to one side of the stopper (1), and a force is applied by the handle (4) to seal the stopper (1) to the gold removal area.

4. The device for removing gold from a region according to claim 3, characterized in that: The bottom of the limiter (1) is grooved; the sealing mechanism is a sealing ring (5) arranged in the groove at the bottom of the limiter (1); the handle (4) applies pressure to transmit the force to the sealing ring (5), and the sealing ring (5) cooperates with the limiter (1) to isolate the gold removal area from other areas.

5. The device for removing gold from a region according to claim 2, characterized in that: The top edge of the limiter (1) is evenly provided with a plurality of mounting plates; the mounting plates are provided with mounting holes; the pressure mechanism is a fastening screw (6) matching the number of the mounting holes; the fastening screw (6) passes through the mounting hole and is connected to the metal-removed part (3), and pressure is applied to the limiter (1) by screwing the fastening screw (6).

6. The device for removing gold from a region according to claim 5, characterized in that: The bottom of the limiter (1) is grooved; the sealing mechanism is a sealing ring (5) arranged in the groove at the bottom of the limiter (1); the tightening screw (6) is screwed to apply pressure to transmit the force to the sealing ring (5), and the sealing ring (5) cooperates with the limiter (1) to isolate the gold removal area from other areas.

7. The device for removing gold from a region according to claim 6, characterized in that: The bottom groove of the stopper (1) is a rectangular groove, a U-shaped groove, a trapezoidal groove or a dovetail groove.

8. The device for removing gold from a region according to claim 7, characterized in that: The sealing ring (5) is made of a high-temperature resistant elastic material, including nitrile rubber, fluororubber or polytetrafluoroethylene.

9. A gold removal method for a regional gold removal device, characterized in that: Using the regional gold removal device as claimed in claim 4; S1: Place the metal-removed part (3) on a hot plate and heat it to a temperature greater than 210 degrees; S2: Place the stopper (1) in the gold removal area, apply pressure through the handle (4), and the sealing ring (5) is deformed by the force. The stopper (1) and the sealing ring (5) isolate the gold removal area, and the stopper (1) and the sealing ring (5) form an independent material cup (2) for the gold removal solder; S3: Melt the gold-removing solder and flux into the material cup. Under the wetting effect of the flux, the gold-removing solder quickly melts the gold-plated layer. S4: Use a desoldering gun to remove the gold solder and flux from the top of the material cup; S5: Repeat the steps S3 to S4 to perform the second gold removal operation and remove the stopper (1); S6: Remove the metal-removed part (3) from the hot plate to cool it down, clean off the residual flux, and the area metal removal is completed.

10. A gold removal method for a regional gold removal device, characterized in that: Using a regional gold removal device as claimed in claim 8; S1: Install the stopper (1) on the metal-removed part (3), tighten the screws, and the sealing ring (5) is deformed by the force. The stopper (1) and the sealing ring (5) isolate the gold-removed area to form an independent material cup (2) for the gold-removed solder; S2: Place the gold-removed solder block into the material cup; S3: The gold-removed part (3) is placed in a eutectic furnace and heated to a temperature greater than 210 degrees. The gold-removing solder melts at high temperature and dissolves the gold-plated layer. S4: After the eutectic furnace cools down, the metal-removed part (3) is taken out and placed on a hot plate with a temperature greater than 210 degrees; S5: After the gold-removing solder in the cup is melted, use a desoldering gun to suck away the solder; S6: Repeat steps S2 to S5 to achieve the second gold removal operation; S7: Remove the metal-removed part (3) from the hot stage, and remove the fastening screws (6) and the limiter (1) in sequence after the metal-removed part (3) cools down, and the metal-removing operation is completed.

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