A welding process for leads on metal packaging shell

Abstract

This application discloses a process for soldering leads on a metal package housing, comprising the following steps: S1. depositing a nickel layer on the leads using a barrel plating method; S2. placing the nickel-coated leads, solder rings, and housing into a mold, and then sintering the mold in a high-temperature environment to solder the leads to the housing; S3. sandblasting the housing with the leads soldered under low pressure. The barrel plating method deposits a nickel layer on the leads, effectively avoiding the rough surface of the leads that is commonly encountered. During high-temperature brazing, the molten solder is less likely to accumulate and flows more smoothly, resulting in a more uniform thickness of the solder layer attached to the lead surface.

Description

Technical Field

[0001] The present application relates to the technical field of electronic packaging, and in particular to a welding process for leads on a metal packaging shell. Background Art

[0002] Metal packaging shells are used for external packaging of precision devices to provide support and protection for precision devices. Currently, metal packaging shells have the advantages of high conversion efficiency, stable performance, high reliability and long life, and are widely used in industrial, military, medical and other fields. Figure 1 As shown, the metal package shell includes a shell 1 and a lead 2. A sealing hole 11 is provided on the shell 1. The lead 2 is welded in the sealing hole 11. One end of the lead 2 is located inside the shell 1, and the other end of the lead 2 is located outside the shell 1. The method for welding the lead 2 in the sealing hole 11 is as follows: first, the lead 2 is installed in the lead hole on the mold, and the solder ring 3 is put on the lead 2. Then, the shell 1 is installed with the inner cavity facing upward into the groove of the mold where the lead and solder ring have been installed. Then, the position of the lead is adjusted so that the lead is aligned with the sealing hole and the lead is installed in the corresponding sealing hole. Then, the insulator 4 is installed in the sealing hole. Then, high-temperature sintering and sandblasting are performed, and finally, nickel and gold electroplating are performed.

[0003] The lead material is 4J50 copper core, and the surface roughness of the lead is large and uneven. As a result, during high-temperature sintering, the molten solder easily accumulates on the surface of the lead and is difficult to disperse evenly, resulting in uneven thickness of the solder layer attached to the surface of the lead, and a gap is easily formed between the solder layer and the surface of the lead, thus affecting the firmness of the lead; moreover, during high-temperature sintering, the molten solder overflows the sealing interface and easily accumulates unevenly in clumps on the outside of the shell. In order to dilute the solder 31 clumps on the shell, it is necessary to spray mixed sand under high pressure. The mixed sand is composed of 70% by mass of 32 The sandblasting layer on the shell is made of a mixture of 0# glass beads and 30% by mass of 150# white corundum. Due to the large physical differences in the components of the mixed sand, the surface of the sandblasting layer on the shell is relatively rough. In addition, the hardness of the glass beads is lower than that of white corundum. Therefore, under the conditions of high-pressure spraying, the glass beads are prone to cracks and dents, which leads to an uneven sandblasting layer on the shell. Regardless of whether the surface of the sandblasting layer is relatively rough or uneven, it is easy to cause electroplating chemicals to remain on the shell during later electroplating, and nickel and gold will also appear, which has a great impact on the product appearance and insulation resistance and other functions. Summary of the Invention

[0004] In order to solve at least one of the above technical problems, a lead welding process is developed in which the lead welding is more firm and the sandblasting layer surface is smoother. The present application provides a welding process for the leads on a metal packaging shell.

[0005] The present application provides a process for welding leads on a metal package housing, comprising the following steps:

[0006] S1. Depositing a nickel layer on the lead by barrel plating;

[0007] S2. Place the lead wire with the nickel layer, the solder ring, and the housing into a mold, and then place the mold in a high-temperature environment for sintering so that the lead wire is brazed to the housing;

[0008] S3. Under low pressure conditions, sandblast the shell with the leads welded to it.

[0009] By adopting the above technical solution, during the barrel plating process, the leads can be frequently polished against each other, so that the nickel layer electroplated on the surface of the leads has better finish, the surface of the nickel layer is smoother, and the thickness fluctuation of the plating is smaller, thereby effectively avoiding the existing phenomenon of rough surface of the lead. Moreover, the use of barrel plating to electroplate the nickel layer on the surface of the lead has high production efficiency and is easy to operate. Since the surface of the nickel layer is relatively smooth, the molten solder is not easy to accumulate during high-temperature brazing and can flow more smoothly, thereby making the thickness of the solder layer attached to the surface of the lead more uniform, and the solder overflowing from the sealing interface is distributed in an annular shape on the outside of the shell. The thickness of the annular solder is relatively uniform and is continuously distributed. Therefore, it is only necessary to sandblast under low pressure conditions to better dilute the solder. The use of low-pressure spraying conditions can effectively avoid the existing high-pressure treatment that causes cracks, depressions, etc. in the sand layer.

[0010] The applicant has completed the welding of leads on thousands of metal packaging shells using the above-mentioned welding process. The leads are welded to the shells relatively firmly, the shells have excellent appearance and functionality, and have received good customer feedback.

[0011] Optionally, in step S1, the thickness of the nickel layer is 2 to 3 um.

[0012] Optionally, before step S2, the step further includes performing furnace annealing on the lead wire with the nickel layer attached thereto.

[0013] By adopting the above technical solution, under high temperature conditions, the nickel in contact with the lead can penetrate into the surface layer of the lead, so that the nickel layer and the lead are integrated into one, thereby making the nickel layer more firmly attached to the lead. After the furnace annealing treatment, it is also possible to check whether the nickel layer has fallen off. The lead with the nickel layer falling off can be recovered for reuse.

[0014] Optionally, the furnace annealing treatment is as follows: placing the lead wire with a nickel layer attached to the surface into a graphite boat, and placing the graphite boat containing the lead wire into a high-temperature furnace with a power of 65 kW.

[0015] Optionally, the furnace consists of a first section furnace, a second section furnace, a third section furnace and a fourth section furnace, and hydrogen or nitrogen passes through the inside of each section furnace. The internal temperature of the first section furnace is 850-870°C, the internal temperature of the second section furnace is 920-930°C, the internal temperature of the third section furnace is 950°C, and the internal temperature of the fourth section furnace is 750-790°C.

[0016] Optionally, in step S2, the solder ring is made of pure silver, and the thickness of the solder ring is 0.19-0.21 mm.

[0017] Optionally, in step S2, the sintering temperature is 965-975° C., and the sintering time is 10-15 minutes.

[0018] Optionally, in step S3, the low pressure is 0.18-0.21 MPa, and the sandblasting material is 320# glass beads.

[0019] By adopting the above technical solution, since a ring-shaped solder with uniform thickness is attached to the shell, it is only necessary to spray 320# glass beads under a low pressure of 0.18 to 0.21 MPa to effectively dilute the solder. The low-pressure spraying condition can effectively avoid the occurrence of cracks in the glass beads. The raw material for sandblasting is a single component, so the surface of the sandblasted layer is smoother, which can avoid the phenomenon of residual electroplating chemicals on the shell during subsequent electroplating.

[0020] Optionally, the method further includes step S4, nickel plating or gold plating the shell after sandblasting.

[0021] In summary, this application includes at least one of the following beneficial technical effects:

[0022] 1. During the barrel plating process for the leads, the leads are frequently polished against each other, resulting in a smoother nickel layer on the lead surface, a smoother surface, and less thickness fluctuation, effectively avoiding the existing rough surface of the lead. Furthermore, barrel plating for nickel plating on the lead surface is highly efficient and easy to operate. Because the nickel layer on the lead surface is smoother and has less thickness fluctuation, molten solder is less likely to accumulate during high-temperature brazing and can flow more smoothly, resulting in a more uniform solder layer on the lead surface. Furthermore, solder overflowing from the sealing interface is distributed in a ring-shaped pattern on the outside of the housing. The ring-shaped solder has a more uniform and continuous thickness, allowing for better dilution of the solder by sandblasting under low-pressure conditions. Low-pressure sandblasting effectively avoids cracks and depressions in the sand layer caused by high-pressure treatment.

[0023] 2. The leads with nickel layer attached are subjected to furnace annealing treatment. Under high temperature conditions, the nickel in contact with the leads can penetrate into the surface layer of the leads, so that the nickel layer and the leads are integrated into one, thereby making the nickel layer more firmly attached to the leads. After the furnace annealing treatment, it is also possible to check whether the nickel layer has fallen off. The leads with the nickel layer falling off can be recycled for reuse.

[0024] 3. Since the shell is covered with a ring-shaped solder of uniform thickness, the solder can be effectively diluted by spraying 320# glass beads at a low pressure of 0.18 to 0.21 MPa. The low-pressure spraying condition can effectively avoid cracks and depressions in the glass beads. In addition, the raw material for sandblasting is a single component, so the surface of the sandblasted layer is smoother, which can avoid the phenomenon of residual electroplating chemicals on the shell during subsequent electroplating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure in which clumps of solder appear on the housing when soldering leads in the prior art;

[0026] Figure 2 This is a schematic diagram of the structure provided by the present application in which the solder is evenly distributed on the housing when welding the leads;

[0027] Explanation of the accompanying reference numerals: 1. Shell; 11. Sealing hole; 2. Lead; 3. Solder ring; 31. Lump of solder; 32. Ring-shaped solder; 4. Insulator. DETAILED DESCRIPTION

[0028] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0029] This application designs a welding process for the leads on the metal packaging shell

[0030] The present invention provides a process for welding leads on a metal package housing, comprising the following steps:

[0031] S1. Depositing a nickel layer on the lead by barrel plating;

[0032] S2. Place the lead wire with the nickel layer, the solder ring, and the housing into a mold, and then place the mold in a high-temperature environment for sintering so that the lead wire is brazed to the housing;

[0033] S3. Under low pressure conditions, sandblast the shell with the leads welded to it.

[0034] After a lot of experiments, the applicant found that the rough and uneven surface of the lead determines the firmness of the lead soldering and is also the key factor causing the solder to accumulate in clumps on the outside of the shell. In view of this, the applicant proposed the technical solution of the present application. During the lead barrel plating process, the leads can be frequently polished against each other, so that the nickel layer electroplated on the lead surface has a better finish, a smoother surface, and less fluctuation in the thickness of the plating layer, thereby effectively avoiding the existing phenomenon of a rough lead surface. Moreover, the nickel layer is electroplated on the lead surface by barrel plating. The production efficiency is high and the operation is convenient. Since the nickel layer electroplated on the surface of the lead is relatively smooth, the molten solder is not easy to accumulate during high-temperature brazing and can flow relatively smoothly, so that the thickness of the solder layer attached to the surface of the lead is relatively uniform, and the solder overflowing from the sealing interface is distributed in an annular shape on the outside of the shell. The thickness of the annular solder is relatively uniform and is continuously distributed. Therefore, it is only necessary to sandblast under low pressure to better dilute the solder. The use of low-pressure spraying conditions can effectively avoid the existing high-pressure treatment that causes cracks, depressions, etc. in the sand layer.

[0035] Example 1

[0036] A welding process for leads on a metal packaging shell comprises the following steps:

[0037] S1, nickel plating

[0038] The lead to be plated, nickel plating solution, and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 10 rpm for 40 minutes to perform horizontal roller plating on the lead to be plated. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead with a thickness of 2um. The roller plating mixture is a 316 stainless steel ball.

[0039] During the barrel plating process, the leads can be frequently polished against each other, thereby improving the smoothness of the nickel layer plated on the lead surface, effectively avoiding the existing phenomenon of rough lead surface. Moreover, the barrel plating method for electroplating the nickel layer on the lead surface has high production efficiency and is easy to operate.

[0040] S2, furnace annealing

[0041] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65 kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein nitrogen gas at a flow rate of 10 L / min is introduced into each furnace section, the internal temperature of the first furnace section is 850°C, and the graphite boat stays in the first furnace section for 70 seconds; the internal temperature of the second furnace section is 920°C, and the graphite boat stays in the second furnace section for 100 seconds; the internal temperature of the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 160 seconds; the internal temperature of the fourth furnace section is 790°C, and the graphite boat stays in the fourth furnace section for 80 seconds.

[0042] The furnace annealing treatment can make the nickel layer better penetrate into the surface of the lead, so that the nickel layer and the lead are integrated into one. After the furnace annealing treatment, it is necessary to check whether the nickel layer has fallen off. The lead with the nickel layer falling off can be recycled for reuse.

[0043] S3, brazing

[0044] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.2mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is brazed on the shell. Figure 2 As shown, the sintering temperature is 975°C and the sintering time is 10 minutes.

[0045] Since the nickel layer electroplated on the surface of the lead has a good finish, the molten solder is not easy to accumulate during high-temperature brazing and can flow smoothly, so that the thickness of the solder layer attached to the surface of the lead is more uniform, and the solder overflowing from the sealing interface is distributed in a ring shape on the outside of the shell. A ring-shaped solder 32 is attached to the shell, such as Figure 2 As shown, the thickness of the ring-shaped solder is relatively uniform and continuously distributed.

[0046] S4, sandblasting

[0047] Under the low pressure condition of 0.2MPa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0048] Since the shell is covered with a ring-shaped solder of uniform thickness, the solder can be diluted well by spraying 320# glass beads under low pressure. The low-pressure spraying condition can effectively avoid the cracks of the glass beads. The raw material of the sandblasting is a single component, so the surface of the sandblasting layer is smoother.

[0049] S5, nickel plating, gold plating

[0050] The sandblasted shell is nickel plated and then gold plated.

[0051] Since the surface of the sandblasting layer is relatively smooth, it can effectively avoid the residual electroplating chemicals on the shell and the occurrence of nickel and gold precipitation.

[0052] Example 2

[0053] A welding process for leads on a metal packaging shell comprises the following steps:

[0054] S1, nickel plating

[0055] The lead to be plated, nickel plating solution and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 15 rpm for 35 minutes. The lead to be plated is subjected to horizontal roller plating treatment. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead. The thickness of the nickel layer is 2.5um. Among them, the roller plating mixture is 316 stainless steel ball.

[0056] S2, furnace annealing

[0057] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65 kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein hydrogen is introduced into each furnace section at a flow rate of 12 L / min, the internal temperature of the first furnace section is 870°C, and the graphite boat stays in the first furnace section for 80 seconds; the internal temperature of the second furnace section is 930°C, and the graphite boat stays in the second furnace section for 100 seconds; the internal temperature of the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 150 seconds; the internal temperature of the fourth furnace section is 750°C, and the graphite boat stays in the fourth furnace section for 90 seconds.

[0058] S3, brazing

[0059] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.21mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is welded to the shell. Figure 2 As shown, the sintering temperature is 965°C and the sintering time is 12 minutes.

[0060] S4, sandblasting

[0061] Under the low pressure condition of 0.18Mpa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0062] S5, nickel plating, gold plating

[0063] The sandblasted shell is nickel plated and then gold plated.

[0064] Example 3

[0065] A welding process for leads on a metal packaging shell comprises the following steps:

[0066] S1, nickel plating

[0067] The lead to be plated, nickel plating solution, and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 5 rpm for 60 minutes to perform horizontal roller plating on the lead to be plated. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead with a thickness of 3um. The roller plating mixture is a 316 stainless steel ball.

[0068] S2, furnace annealing

[0069] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65 kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein nitrogen gas with a flow rate of 11 L / min is introduced into each furnace section. The temperature inside the first furnace section is 860°C, and the graphite boat stays in the first furnace section for 75 seconds; the temperature inside the second furnace section is 915°C, and the graphite boat stays in the second furnace section for 90 seconds; the temperature inside the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 120 seconds; the temperature inside the fourth furnace section is 755°C, and the graphite boat stays in the fourth furnace section for 85 seconds.

[0070] S3, brazing

[0071] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.19mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is welded to the shell. Figure 2 As shown, the sintering temperature is 968°C and the sintering time is 14 minutes.

[0072] S4, sandblasting

[0073] Under the low pressure condition of 0.21Mpa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0074] S5, nickel plating, gold plating

[0075] The sandblasted shell is nickel plated and then gold plated.

[0076] Example 4

[0077] A welding process for leads on a metal packaging shell comprises the following steps:

[0078] S1, nickel plating

[0079] The lead to be plated, nickel plating solution, and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 8 rpm for 50 minutes to perform horizontal roller plating on the lead to be plated. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead with a thickness of 2.8um. ​​The roller plating mixture is a 316 stainless steel ball.

[0080] S2, furnace annealing

[0081] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein nitrogen gas with a flow rate of 13L / min is introduced into each furnace section. The temperature inside the first furnace section is 855°C, and the graphite boat stays in the first furnace section for 74 seconds; the temperature inside the second furnace section is 925°C, and the graphite boat stays in the second furnace section for 95 seconds; the temperature inside the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 140 seconds; the temperature inside the fourth furnace section is 775°C, and the graphite boat stays in the fourth furnace section for 88 seconds.

[0082] S3, brazing

[0083] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.2mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is welded to the shell. Figure 2 As shown, the sintering temperature is 970°C and the sintering time is 13 minutes.

[0084] S4, sandblasting

[0085] Under the low pressure condition of 0.2Mpa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0086] S5, nickel plating, gold plating

[0087] The sandblasted shell is nickel plated and then gold plated.

[0088] Example 5

[0089] A welding process for leads on a metal packaging shell comprises the following steps:

[0090] S1, nickel plating

[0091] The lead to be plated, nickel plating solution, and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 6 rpm for 45 minutes. The lead to be plated is subjected to horizontal roller plating treatment. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead with a thickness of 2.6um. The roller plating mixture is a 316 stainless steel ball.

[0092] S2, furnace annealing

[0093] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65 kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein hydrogen is introduced into each furnace section at a flow rate of 15 L / min. The temperature inside the first furnace section is 862°C, and the graphite boat stays in the first furnace section for 70 seconds; the temperature inside the second furnace section is 920°C, and the graphite boat stays in the second furnace section for 98 seconds; the temperature inside the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 135 seconds; the temperature inside the fourth furnace section is 765°C, and the graphite boat stays in the fourth furnace section for 86 seconds.

[0094] S3, brazing

[0095] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.2mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is welded to the shell. Figure 2 As shown, the sintering temperature is 972°C and the sintering time is 15 minutes.

[0096] S4, sandblasting

[0097] Under the low pressure condition of 0.2Mpa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0098] S5, nickel plating, gold plating

[0099] The sandblasted shell is nickel plated and then gold plated.

[0100] Example 6

[0101] A welding process for leads on a metal packaging shell comprises the following steps:

[0102] S1, nickel plating

[0103] The lead to be plated, nickel plating solution, and roller plating mixture are placed in a drum, and the drum is rotated at a speed of 12 rpm for 55 minutes to perform horizontal roller plating on the lead to be plated. After that, the lead is taken out and a nickel layer is deposited on the surface of the lead with a thickness of 3um. The roller plating mixture is a 316 stainless steel ball.

[0104] S2, furnace annealing

[0105] A lead with a nickel layer attached to its surface is placed in a graphite boat, and the graphite boat containing the lead is placed in a furnace with a power of 65kW. The furnace consists of a first furnace section, a second furnace section, a third furnace section and a fourth furnace section, wherein nitrogen gas with a flow rate of 14L / min is introduced into each furnace section. The temperature inside the first furnace section is 865°C, and the graphite boat stays in the first furnace section for 72 seconds; the temperature inside the second furnace section is 922°C, and the graphite boat stays in the second furnace section for 94 seconds; the temperature inside the third furnace section is 950°C, and the graphite boat stays in the third furnace section for 125 seconds; the temperature inside the fourth furnace section is 770°C, and the graphite boat stays in the fourth furnace section for 90 seconds.

[0106] S3, brazing

[0107] Install the lead wire 2 after furnace annealing into the lead wire hole 11 on the mold, and put the pure silver solder ring 3 on the lead wire 2. The thickness of the pure silver solder ring is 0.2mm. Then, install the shell 1 with the inner cavity facing upward into the mold groove where the lead wire and the pure silver solder ring have been installed. Then, adjust the position of the lead wire so that the lead wire is aligned with the sealing hole and the lead wire is installed in the corresponding sealing hole. Then, install the insulator 4 into the sealing hole. After that, put the mold into the tunnel furnace protected by nitrogen and hydrogen and sinter it so that the lead wire 2 is welded to the shell. Figure 2 As shown, the sintering temperature is 968°C and the sintering time is 13 minutes.

[0108] S4, sandblasting

[0109] Under the low pressure condition of 0.19Mpa, the surface of the shell with the lead welded is sandblasted, and the raw material used for sandblasting is 320# glass beads.

[0110] S5, nickel plating, gold plating

[0111] The sandblasted shell is nickel plated and then gold plated.

[0112] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A welding process for leads on a metal packaging shell, characterized in that: The steps include: S1. Depositing a nickel layer on the lead by barrel plating; S2. Place the lead wire with the nickel layer, the solder ring, and the housing into a mold, and then place the mold in a high-temperature environment for sintering so that the lead wire is brazed to the housing; S3. Under low pressure conditions, sandblast the shell with the leads welded to it.

2. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: In step S1, the thickness of the nickel layer is 2-3 μm.

3. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: Before step S2, the lead wire with the nickel layer attached thereto is subjected to furnace annealing.

4. The welding process for leads on a metal packaging shell according to claim 3, characterized in that: The furnace annealing treatment is as follows: the lead wire with a nickel layer attached to the surface is placed in a graphite boat, and the graphite boat containing the lead wire is placed in a high-temperature furnace with a power of 65kW.

5. The welding process for leads on a metal packaging shell according to claim 4, characterized in that: The furnace consists of a first section furnace, a second section furnace, a third section furnace and a fourth section furnace. Hydrogen or nitrogen passes through the interior of each section furnace. The internal temperature of the first section furnace is 850-870°C, the internal temperature of the second section furnace is 920-930°C, the internal temperature of the third section furnace is 950°C, and the internal temperature of the fourth section furnace is 750-790°C.

6. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: In step S2, the solder ring is made of pure silver, and the thickness of the solder ring is 0.19-0.21 mm.

7. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: In step S2, the sintering temperature is 965-975° C., and the sintering time is 10-15 minutes.

8. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: In step S3, the low pressure is 0.18-0.21 MPa, and the sandblasting material is 320# glass beads.

9. The welding process for leads on a metal packaging shell according to claim 1, characterized in that: The method further includes step S4 of nickel plating and gold plating the shell after sandblasting.

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