Continuous high-speed tin plating process for electronic components

Abstract

The invention belongs to the field of production of electronic components, and particularly relates to a continuous high-speed tin plating process for electronic components. In order to solve the problems that in the prior art, a pure tin electroplating technology is poor in production continuity, low in efficiency, unstable in tin coating quality, prone to discoloration in the tin coating storage process, poor in oxidation resistance, prone to tin whisker growth and the like, the invention provides the continuous high-speed tin plating technology for the electronic component. Through the technological processes of automatic feeding, electrolytic softening, high-pressure water jet cutting, deoxidation, presoaking, pure tin electroplating, deionized hot water washing, neutralization, tin protection, air knife blow-drying, drying, discharging, steel strip electrolytic tin stripping and secondary drying, the production continuity and the production efficiency are improved, the quality and the oxidation resistance of a tin layer are guaranteed, and growth of tin whiskers is effectively prevented.

Description

Technical Field

[0001] The present application belongs to the field of electronic component production, and in particular relates to a continuous high-speed tinning process for electronic components. Background Art

[0002] With the rapid development of the electronics industry, the trend of miniaturization and thinness of electronic components is becoming increasingly obvious. As an important surface treatment technology, electroplating technology plays a vital role in improving the performance of electronic components, especially in the field of electroplating pure tin, which is widely used in connectors, integrated circuit packaging and other fields. However, there are some problems with the traditional electroplating pure tin process, which directly affect the performance and reliability of electronic components.

[0003] In the traditional electroplating process, electronic components are usually placed in the electroplating tank by manual loading. This method is not only inefficient, but also easily causes damage to electronic components during the loading process. Due to the limitations of manual loading, the traditional electroplating process often cannot achieve continuous production, resulting in low production efficiency. The existing electroplating process is difficult to ensure the uniformity of the coating, especially in the case of complex shapes of electronic components, the current distribution is often uneven, which will lead to inconsistent coating thickness, and inconsistent coating thickness will lead to differences in electrical performance. Due to the lack of effective pre-treatment and post-treatment steps, the coating is prone to cracks, bubbles and other problems, and due to insufficient adhesion between the coating and the substrate, the coating is easy to fall off, affecting the service life and performance of electronic components. The poor oxidation resistance of the coating in the traditional electroplating process causes the coating to easily undergo oxidation reactions during storage, and then discolor. The discoloration not only affects the appearance quality of electronic components, but also may reduce their market competitiveness.

[0004] In the existing electroplating process, the plating layer is prone to produce tin whiskers, which are tiny metal filaments that grow randomly on the surface of the plating layer and may cause problems such as short circuits. The presence of tin whiskers greatly threatens the long-term reliability of electronic components, especially in high-precision circuits. Summary of the invention

[0005] In order to solve the problems of poor production continuity, low efficiency, unstable quality of tin-plated layer, easy discoloration of tin-plated layer during storage, poor antioxidant capacity, easy growth of tin whiskers in tin-plated layer, etc. in the prior art electroplating pure tin process, the present application provides a continuous high-speed tin-plating process for electronic components. The process provided by the present application improves production continuity and production efficiency through the process flow of automatic loading, electrolytic softening, high-pressure water jet, deoxidation, pre-impregnation, electroplating pure tin, deionized hot water washing, neutralization, tin protection, air knife drying, drying, unloading, electrolytic tin stripping of steel strip, and secondary drying, ensures the quality and antioxidant capacity of the tin layer, and effectively prevents the growth of tin whiskers.

[0006] The present application provides a continuous high-speed tinning process for electronic components, comprising the following steps:

[0007] S1. Hang the packaged electronic components on the circulating steel belt, and fix the conductive side of the electronic components to the moving steel belt through the spring clips on the steel belt to ensure the requirement of continuous production; first enter the electrolytic softening station to electrolyze and soften the overflow of the packaging resin, the electrolytic voltage is 0-4V, the electrolysis time is 60s-90s, and then use tap water to wash, and blow dry with an air knife after washing;

[0008] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station, clean up the electrolytic softened resin overflow, and then use tap water to wash, and then use air knife to blow dry. The pressure of the high-pressure water jet is 200kg / cm 2 -300kg / cm 2 , the cleaning time is 20s-40s;

[0009] S3. After the electronic components have been treated with a high-pressure water jet, they enter the deoxidation station for 10s-20s, and are then cleaned with deionized water and blown dry with an air knife.

[0010] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, using a current of 5A-30A for 10s-20s, and then cleaned with deionized water, and blown dry with an air knife after cleaning;

[0011] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The pure tin electroplating station is divided into three sections. The first section uses a current density of 20A / dm 2 -30A / dm 2 The time is 20s-30s, and the second stage uses a current density of 10A / dm 2 -20A / dm 2 The time is 20s-30s, and the third stage uses a current density of 10A / dm 2 -20A / dm 2 , the time is 20s-30s, rinse with tap water and then clean with deionized water, and then blow dry with an air knife;

[0012] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 10s-20s, and then are washed with deionized water and blown dry with an air knife after washing;

[0013] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 10s-20s. They are then washed with deionized water and dried with an air knife. The neutralization powder contains 60-90% of inorganic acid salt and 10-40% of organic acid salt.

[0014] S8. After the neutralization treatment, the electronic components enter the tin protection station, where they are immersed for 10s-20s and then cleaned with deionized water; the immersion solution in the tin protection station is a single-component weak acid that does not contain any complex;

[0015] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 15s-25s. After the air knife drying treatment, the electronic components enter the drying station again, and the drying time is 10s-20s.

[0016] S10, the electronic components after drying enter the unloading station, manually receive the materials and put them into the drying box for unloading, and then enter the electrolytic tin stripping station. The tin stripping station is divided into two sections. The first section tin stripping voltage is 0.5V-2.5V, and the tin stripping time is 20s-40s; the second section tin stripping voltage is 0.5V-2.5V, and the tin stripping time is 20s-40s;

[0017] S11. The electronic components after unloading are subjected to secondary drying at a drying temperature of 140°C-160°C and a drying time of 50min-70min.

[0018] Furthermore, the electrolytic softening step in S1 uses an electrolytic softening solution containing 150g / L-250g / L of electrolyte (components) and a solution temperature of 50°C-70°C.

[0019] Furthermore, the deoxidation step in S3 uses a deoxidation solution containing 45 ml / L-75 ml / L of sulfuric acid, 80 g / L-120 g / L of T-802 deoxidant, and a temperature of 30°C-60°C.

[0020] Furthermore, in the pre-dipping step of S4, a pre-dipping solution is used, which contains 70 g / L-130 g / L of methanesulfonic acid, and the pre-dipping temperature is room temperature.

[0021] Furthermore, in the pure tin electroplating step S5, the stannous ion concentration in the tin plating solution is 60g / L-80g / L, the methanesulfonic acid concentration is 220g / L-280g / L, the additive concentration is 60g / L-120g / L, and the solution temperature is 40°C-60°C.

[0022] Furthermore, the soaking temperature of the deionized hot water washing step in S6 is 30°C-70°C.

[0023] Furthermore, the soaking temperature in the neutralization step of S7 is 30°C-50°C.

[0024] Furthermore, the tin protection step in S8 has an immersion temperature of 20°C-60°C.

[0025] Furthermore, the position of the wind knife outlet in S9 forms an angle of 35 degrees to 45 degrees with the movement direction of the electronic components.

[0026] Furthermore, the drying temperature in S9 is 120°C-170°C.

[0027] Furthermore, the concentration of the electrolytic tin stripping solution (component) in S10 is 250ml / L-350ml / L, and the temperature is 30℃-50℃.

[0028] The beneficial effects of this application are:

[0029] Through the automatic or semi-automatic feeding system, the electronic components can be quickly positioned and fixed, greatly improving the production efficiency. This design reduces the number of manual interventions, reduces the error rate in the production process, and also reduces the labor intensity of workers. The use of a circularly moving steel belt as a carrier ensures that the electronic components can move continuously on the production line, thereby achieving efficient and continuous production. The design of the steel belt conducting electricity through the conductive block ensures that the conductivity requirements of the electronic components during the electroplating process are met. Fixing one side of the electronic component to the moving steel belt through a spring clip ensures the stability of the electronic component during the electroplating process, while ensuring the continuous production requirements of the electronic components.

[0030] Removing the encapsulation resin overflow through the electrolytic softening process ensures the cleanliness of the electronic device surface in the subsequent process steps, which helps to improve the quality of the plating. Using a high-pressure water jet to further remove the residual resin overflow ensures a thorough cleaning of the surface. The pressure and time settings of the high-pressure water jet can effectively remove difficult-to-clean residues and provide a clean surface for the subsequent electroplating steps.

[0031] The pure tin electroplating step sets different current densities in three stages, with a higher current density in the first stage and lower current density in the second and third stages, ensuring the stability and uniformity of the coating quality. This segmented current density design helps to form a good grain structure in the early stage of plating, thereby improving the quality of the entire coating. Through the treatment of the tin protection station, the oxidation resistance of the tin coating is improved, and the possibility of discoloration of the coating during storage is reduced. This step is crucial to extending the service life of electronic components.

[0032] The growth of tin whiskers is effectively prevented through a high-temperature and long-term secondary drying process, which is essential for improving the reliability and service life of electronic components. The deoxidation treatment carried out at a certain temperature by the combined use of sulfuric acid and T-802 deoxidizer helps to remove the oxide layer on the surface and prepare a cleaner surface for the subsequent electroplating step. The pre-dip treatment provides the necessary conditions for electroplating pure tin by setting the appropriate methanesulfonic acid concentration and time, which helps to form a more uniform coating. The concentration setting of stannous ions, methanesulfonic acid and additives in the tinning solution, as well as the appropriate temperature control, are all to ensure the quality and stability of the coating. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0034] In the description of the embodiments of the present application, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships that are customarily placed when the product of the application is used, or are orientations or positional relationships that are customarily understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0035] Example 1

[0036] S1. Put the packaged electronic components into the automatic device one by one, and then hang them on the circulating steel belt. The conductive side of the electronic components is fixed to the moving steel belt through the spring clip on the steel belt, which ensures the continuous production requirements of the electronic components. The steel belt conducts electricity through the conductive block, which ensures the conductivity requirements of the electronic components. The electronic components enter the electrolytic softening station for electrolytic softening of the packaging resin overflow. The electrolytic voltage is 4V and the electrolytic time is 60s. Then there are 3 tap water washes, and after washing, there is a wind knife to blow dry.

[0037] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station to clean up the electrolytic softened resin overflow, and then wash with tap water for 3 times, and then blow dry with an air knife; the pressure of the high-pressure water jet is 300kg / cm 2 , time is 20s.

[0038] S3. After the electronic components have been treated by the high-pressure water jet, they enter the deoxidation station for 10 seconds, and then are cleaned with three passes of deionized water. After cleaning, they are dried with an air knife.

[0039] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, with a current of 30A for 10s, and then three deionized water cleanings, followed by air knife drying.

[0040] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The electroplating station is equipped with a spray cavity shielding device, which can be adjusted according to the width of the product. The electroplating station is divided into three sections. The first section uses a current density of 30A / dm 2 , the time is 20s, and the second stage uses a current density of 20A / dm 2, time is 20s, the third stage uses a current density of 20A / dm 2 , the time is 20s. The current density in the first section is higher than that in the last two sections. This is to give an impact current at the beginning of tin electroplating to ensure the good quality of the initial tin electroplating layer, thereby ensuring the stability of the quality of the entire tin layer; the thickness of the pure tin layer is 8-10μm, and then there is 1 tap water rinse, followed by 3 deionized water rinses, and then blow-dried with a wind knife.

[0041] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 10 seconds, followed by 3 deionized water washes, and then blown dry with an air knife.

[0042] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 10 seconds. They are then washed with deionized water for 3 times and dried with an air knife after washing.

[0043] S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 10 seconds, and then are cleaned with 3 deionized water.

[0044] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 15 seconds; after the air knife drying treatment, the electronic components enter the drying station, and the drying time is 10 seconds.

[0045] S10. After the electronic components have been dried, they enter the unloading station, where they are manually connected and then loaded into drying boxes. After the steel strip is unloaded, it enters the electrolytic tin stripping station, which is divided into two sections. The first section has a tin stripping voltage of 2.5V and a tin stripping time of 20s. The second section has a tin stripping voltage of 2.5V and a tin stripping time of 20s.

[0046] S11. The electronic components after unloading are subjected to secondary drying at a drying temperature of 150° C. for 60 minutes.

[0047] Example 2

[0048] S1. Put the packaged electronic components into the automatic device one by one, and then hang them on the circulating steel belt; the spring clips on the steel belt fix the conductive side of the electronic components to the moving steel belt, ensuring the continuous production of electronic components; the steel belt conducts electricity through the conductive blocks, ensuring the conductivity of the electronic components; the electronic components enter the electrolytic softening station for electrolytic softening of the packaging resin overflow, the electrolytic voltage is 2V, the electrolysis time is 90s, and then there are 3 tap water cleanings, and after cleaning, there is a wind knife to blow dry.

[0049] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station to clean up the electrolytic softened resin overflow, and then wash with tap water for 3 times, and then blow dry with an air knife; the pressure of the high-pressure water jet is 200kg / cm2 , time is 40s.

[0050] S3. After the electronic components have been treated by the high-pressure water jet, they enter the deoxidation station for 20 seconds, and then are cleaned with three passes of deionized water. After cleaning, they are dried with an air knife.

[0051] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, with a current of 5A for 20S, and then three deionized water cleanings, followed by air knife drying.

[0052] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The electroplating station is equipped with a spray cavity shielding device, which can be adjusted according to the width of the product. The electroplating station is divided into three sections. The first section uses a current density of 20A / dm 2 , the time is 30S, and the second stage uses a current density of 10A / dm 2 , time is 30S, the third section uses a current density of 10A / dm, time is 30S, the current density of the first section is higher than the last two sections, just to give impact current at the beginning of electroplating tin to ensure the good quality of the initial electroplating tin layer, thereby ensuring the stability of the quality of the entire tin layer; the thickness of the pure tin layer is 6μm-8μm, and then there is 1 tap water rinse, followed by 3 deionized water rinses, and then blow-dried with a wind knife.

[0053] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 20 seconds, followed by 3 deionized water washings, and then blow-dried with air knives.

[0054] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 20 seconds. They are then washed with deionized water for 3 times and dried with an air knife after washing.

[0055] S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 20 seconds, and then are cleaned with 3 deionized water.

[0056] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 25S; after the air knife drying treatment, the electronic components enter the drying station, and the drying time is 20S.

[0057] S10. After the electronic components have been dried, they enter the unloading station, where they are manually connected and then loaded into drying boxes. After the steel strip is unloaded, it enters the electrolytic tin stripping station, which is divided into two sections. The first section has a tin stripping voltage of 2V and a tin stripping time of 40S. The second section has a tin stripping voltage of 2V and a tin stripping time of 40S.

[0058] S11. The electronic components after unloading are subjected to secondary drying at a drying temperature of 160° C. for 50 minutes.

[0059] Example 3

[0060] S1. Put the packaged electronic components into the automatic device one by one, and then hang them on the circulating steel belt; the spring clips on the steel belt fix the conductive side of the electronic components to the moving steel belt, ensuring the continuous production of electronic components; the steel belt conducts electricity through the conductive blocks, ensuring the conductivity of the electronic components; the electronic components enter the electrolytic softening station for electrolytic softening of the packaging resin overflow, the electrolytic voltage is 0V, the electrolysis time is 70s, and then there are 3 tap water cleanings, and after cleaning, there is a wind knife to blow dry.

[0061] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station to clean up the electrolytic softened resin overflow, and then have 3 tap water washes, and then blow dry with an air knife; the pressure of the high-pressure water jet is 250kg / cm 2 , time is 30s.

[0062] S3. After the electronic components have been treated by the high-pressure water jet, they enter the deoxidation station for 150 seconds, and then are cleaned with three passes of deionized water, and then blown dry with an air knife.

[0063] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, using a current of 5A-30A for 10S-20S, and then three deionized water washes, followed by air knife drying.

[0064] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The electroplating station is equipped with a spray cavity shielding device, which can be adjusted according to the width of the product. The electroplating station is divided into three sections. The first section uses a current density of 25A / dm 2 , the time is 20S-30S, and the second stage uses a current density of 15A / dm 2 , time is 25S, the third stage uses a current density of 15A / dm 2 , the time is 25S. The current density in the first section is higher than that in the last two sections. This is to give an impact current at the beginning of tin electroplating to ensure the good quality of the initial tin electroplating layer, thereby ensuring the stability of the quality of the entire tin layer; the thickness of the pure tin layer is 8μm-10μm, and then there is 1 tap water rinse, followed by 3 deionized water rinses, and then blow-dried with a wind knife.

[0065] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 15 seconds, followed by 3 deionized water washes, and then blow-dried with an air knife.

[0066] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 15 seconds. They are then washed with deionized water for 3 times and dried with an air knife after washing.

[0067] S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 15 seconds, and then are cleaned with 3 deionized water.

[0068] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 20S; after the air knife drying treatment, the electronic components enter the drying station, and the drying time is 15S.

[0069] S10. After the electronic components have been dried, they enter the unloading station, where they are manually connected and then loaded into drying boxes. After the steel strip is unloaded, it enters the electrolytic tin stripping station, which is divided into two sections. The first section has a tin stripping voltage of 1.0V and a tin stripping time of 30S. The second section has a tin stripping voltage of 1.0V and a tin stripping time of 30S.

[0070] S11. The electronic components after unloading are subjected to secondary drying at a drying temperature of 140° C. for 70 minutes.

[0071] Comparative Example 1

[0072] S1. Put the packaged electronic components into the automatic device one by one, and then hang them on the circulating steel belt; the spring clips on the steel belt fix the conductive side of the electronic components to the moving steel belt, ensuring the continuous production of electronic components; the steel belt conducts electricity through the conductive blocks, ensuring the conductivity of the electronic components; the electronic components enter the electrolytic softening station for electrolytic softening of the packaging resin overflow, the electrolytic voltage is 2V, the electrolysis time is 90s, and then there are 3 tap water cleanings, and after cleaning, there is a wind knife to blow dry.

[0073] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station to clean up the electrolytic softened resin overflow, and then wash with tap water for 3 times, and then blow dry with an air knife; the pressure of the high-pressure water jet is 200kg / cm 2 , time is 40s.

[0074] S3. After the electronic components have been treated by the high-pressure water jet, they enter the deoxidation station for 20 seconds, and then are cleaned with three passes of deionized water. After cleaning, they are dried with an air knife.

[0075] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, with a current of 5A for 20S, and then three deionized water cleanings, followed by air knife drying.

[0076] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The electroplating station is equipped with a spray cavity shielding device, which can be adjusted according to the width of the product. The electroplating station uses a current density of 20A / dm 2, the time is 90S, the thickness of the pure tin layer is 6μm-8μm, then there is 1 tap water rinse, followed by 3 deionized water rinses, and then air knife drying.

[0077] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 20 seconds, followed by 3 deionized water washings, and then blow-dried with air knives.

[0078] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 20 seconds. They are then washed with deionized water for 3 times and dried with an air knife after washing.

[0079] S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 20 seconds, and then are cleaned with 3 deionized water.

[0080] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 25S; after the air knife drying treatment, the electronic components enter the drying station, and the drying time is 20S.

[0081] S10. After the electronic components have been dried, they enter the unloading station, where they are manually connected and then loaded into drying boxes. After the steel strip is unloaded, it enters the electrolytic tin stripping station, which is divided into two sections. The first section has a tin stripping voltage of 2V and a tin stripping time of 40S. The second section has a tin stripping voltage of 2V and a tin stripping time of 40S.

[0082] S11. The electronic components after unloading are subjected to secondary drying at a drying temperature of 160° C. for 50 minutes.

[0083] Comparative Example 2

[0084] S1. Put the packaged electronic components into the automatic device one by one, and then hang them on the circulating steel belt; the spring clips on the steel belt fix the conductive side of the electronic components to the moving steel belt, ensuring the continuous production of electronic components; the steel belt conducts electricity through the conductive blocks, ensuring the conductivity of the electronic components; the electronic components enter the electrolytic softening station for electrolytic softening of the packaging resin overflow, the electrolytic voltage is 0V, the electrolysis time is 70s, and then there are 3 tap water cleanings, and after cleaning, there is a wind knife to blow dry.

[0085] S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station to clean up the electrolytic softened resin overflow, and then have 3 tap water washes, and then blow dry with an air knife; the pressure of the high-pressure water jet is 250kg / cm 2 , time is 30s.

[0086] S3. After the electronic components have been treated by the high-pressure water jet, they enter the deoxidation station for 150 seconds, and then are cleaned with three passes of deionized water, and then blown dry with an air knife.

[0087] S4. After the deoxidation treatment, the electronic components enter the pre-preg station, using a current of 5A-30A for 10S-20S, and then three deionized water washes, followed by air knife drying.

[0088] S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The electroplating station is equipped with a spray cavity shielding device, which can be adjusted according to the width of the product. The electroplating station is divided into three sections. The first section uses a current density of 25A / dm 2 , the time is 20S-30S, and the second stage uses a current density of 15A / dm 2 , time is 25S, the third stage uses a current density of 15A / dm 2 , the time is 25S. The current density in the first section is higher than that in the last two sections. This is to give an impact current at the beginning of tin electroplating to ensure the good quality of the initial tin electroplating layer, thereby ensuring the stability of the quality of the entire tin layer; the thickness of the pure tin layer is 8μm-10μm, and then there is 1 tap water rinse, followed by 3 deionized water rinses, and then blow-dried with a wind knife.

[0089] S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 15 seconds, followed by 3 deionized water washes, and then blow-dried with an air knife.

[0090] S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 15 seconds. They are then washed with deionized water for 3 times and dried with an air knife after washing.

[0091] S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 15 seconds, and then are cleaned with 3 deionized water.

[0092] S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 20S; after the air knife drying treatment, the electronic components enter the drying station, and the drying time is 15S.

[0093] S10. After the electronic components have been dried, they enter the unloading station, where they are manually connected and then loaded into drying boxes. After the steel strip is unloaded, it enters the electrolytic tin stripping station, which is divided into two sections. The first section has a tin stripping voltage of 1.0V and a tin stripping time of 30S. The second section has a tin stripping voltage of 1.0V and a tin stripping time of 30S.

[0094] According to the high temperature test conditions of GB / T2423.2 and JESD22-A103 at 150±3° and 168H, observing the discoloration of the tin layer can reflect the antioxidant capacity of the tin layer.

[0095] Antioxidation ability of tin coating Example 1 No discoloration Example 2 No discoloration Example 3 No discoloration Comparative Example 1 More color changes Comparative Example 2 More color changes

[0096] The test was conducted according to the JEDEC JESD201-2006 Tin Susceptibility and Surface Processing Environmental Acceptance Requirements, -55℃(+0 / -10℃)~85℃(+10 / -0℃), atmospheric environment, 3 cycles / h. During the experiment, the growth of tin whiskers was observed after every 500 cycles; a total of 1500 cycles were conducted, and the growth status of tin whiskers was observed three times.

[0097]

[0098]

[0099] It can be seen that the anti-oxidation performance of Comparative Examples 1 and 2 is weaker than that of Examples 1-3, and the density of tin whiskers is greater than that of Examples 1-3. The scheme of the embodiment ensures the quality and anti-oxidation ability of the tin layer and effectively prevents the growth of tin whiskers.

Claims

1. A continuous high-speed tinning process for electronic components, characterized in that: The following steps are involved: S1. Hang the packaged electronic components on a circulating steel belt and enter the electrolytic softening station to electrolytically soften the overflow of the packaging resin. The electrolytic voltage is 0-4V and the electrolytic time is 60s-90s. Then use tap water to wash and blow dry with an air knife after washing; S2. After the electrolytic softening treatment, the electronic components enter the high-pressure water jet station, clean up the electrolytic softened resin overflow, and then use tap water to wash, and then use air knife to blow dry. The pressure of the high-pressure water jet is 200kg / cm 2 -300kg / cm 2 , the cleaning time is 20s-40s; S3. After the electronic components have been treated with a high-pressure water jet, they enter the deoxidation station for 10s-20s, and are then cleaned with deionized water and blown dry with an air knife. S4. After the deoxidation treatment, the electronic components enter the pre-preg station, using a current of 5A-30A for 10s-20s, and then cleaned with deionized water, and blown dry with an air knife after cleaning; S5. After the pre-impregnation treatment, the electronic components enter the pure tin electroplating station. The pure tin electroplating station is divided into three sections. The first section uses a current density of 20A / dm 2 -30A / dm 2 The time is 20s-30s, and the second stage uses a current density of 10A / dm 2 -20A / dm 2 The time is 20s-30s, and the third stage uses a current density of 10A / dm 2 -20A / dm 2 , the time is 20s-30s, rinse with tap water and then clean with deionized water, and then blow dry with an air knife; S6. After the electronic components are electroplated with pure tin, they enter the deionized hot water washing station for 10s-20s, and then are washed with deionized water and blown dry with an air knife after washing; S7. After the electronic components have been washed with deionized hot water, they enter the neutralization station and are immersed for 10s-20s. They are then washed with deionized water and dried with an air knife. S8. After the neutralization treatment, the electronic components enter the tin protection station, soak for 10s-20s, and then use deionized water to clean; S9. After the tin protection treatment, the electronic components enter the air knife drying station, and the drying time is 15s-25s. After the air knife drying treatment, the electronic components enter the drying station again, and the drying time is 10s-20s. S10, the electronic components after drying enter the unloading station, manually receive the materials and put them into the drying box for unloading, and then enter the electrolytic tin stripping station. The tin stripping station is divided into two sections. The first section tin stripping voltage is 0.5V-2.5V, and the tin stripping time is 20s-40s; the second section tin stripping voltage is 0.5V-2.5V, and the tin stripping time is 20s-40s; S11. The electronic components after unloading are subjected to secondary drying at a temperature of 140°C-160°C and a drying time of 50min-70min.

2. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: In the electrolytic softening step S1, the electrolyte concentration is 50g / L-250g / L, and the solution temperature is 50°C-70°C.

3. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The deoxidation step S3 uses a deoxidation solution containing 45 ml / L-75 ml / L of sulfuric acid, 80 g / L-120 g / L of a deoxidant, and a temperature of 30°C-60°C.

4. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: In the pre-dipping step S4, a pre-dipping solution is used, which contains 70 g / L-130 g / L of methanesulfonic acid, and the pre-dipping temperature is room temperature.

5. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: In the pure tin electroplating step S5, the concentration of stannous ions in the tin plating solution is 60g / L-80g / L, the concentration of methanesulfonic acid is 220g / L-280g / L, and the solution temperature is 40°C-60°C.

6. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The soaking temperature of the deionized hot water washing step S6 is 30°C-70°C.

7. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The immersion temperature in the neutralization step S7 is 30°C-50°C, and the immersion temperature in the tin protection step S8 is 20°C-60°C.

8. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The position of the wind knife outlet in S9 forms an angle of 35 degrees to 45 degrees with the movement direction of the electronic components.

9. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The drying temperature in S9 is 120°C-170°C.

10. The continuous high-speed tinning process for electronic components according to claim 1, characterized in that: The concentration of the electrolytic tin stripping solution in S10 is 250ml / L-350ml / L, and the temperature is 30℃-50℃.

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