Roll-to-roll continuous electroplating process

Abstract

The invention belongs to the field of production of electronic components, and particularly relates to a roll-to-roll continuous electroplating process. The technological process comprises the steps that ultrasonic oil removal and electrolytic treatment are carried out to clean a base material, and activating treatment is carried out to enhance the surface activity; pre-plated copper forms a protective film; replacement liquid is prevented from avoiding plating of a non-functional area; mold positioning is adopted to realize precise local silver plating; silver resources are saved, the thickness of a silver layer is reduced through electrolytic silver removal, the corrosion resistance is improved through silver protection treatment, selective tin plating is realized through a material belt overturning device, and it is ensured that a plating layer is uniform and free of the risk of skip plating; and finally, the production is completed through tin protection, suction drying and drying, so that the traditional multi-step process is simplified, the conductivity and the welding performance are improved, meanwhile, unnecessary cost and material consumption are reduced, the requirement that single-strip or single-grain tin electroplating is not needed after packaging is met, and the production efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the field of electronic component production, and in particular relates to a roll-to-roll continuous electroplating process. Background Art

[0002] Lead frame is one of the key components in semiconductor packaging. Its main function is to establish electrical connection between semiconductor chip and external circuit. With the development trend of miniaturization and lightweight of electronic equipment, the requirements for lead frame are also increasing. It not only needs to have good electrical conductivity, but also needs to meet the characteristics of corrosion resistance and oxidation resistance. As a key process to improve the surface characteristics of lead frame, the quality and efficiency of electroplating directly affect the performance and cost of the final product.

[0003] The traditional lead frame electroplating process mainly includes a series of steps such as continuous silver plating, cutting into strips, chip pasting, wire bonding, and packaging molding. In order to ensure the uniformity and adhesion of the subsequent plating, the lead frame needs to be pre-silvered first, and then the entire lead frame is fully silver-plated to prevent the copper substrate from oxidizing during the plastic packaging process and ensure that the functional area of ​​the lead frame has good conductivity and weldability. Then, selective silver plating is performed in specific functional areas to meet the performance requirements of different parts. Finally, the packaged lead frame is stripped and electroplated with tin to enhance its weldability and oxidation resistance.

[0004] In this process, in order to ensure that the functional area of ​​the lead frame has excellent conductivity and weldability, silver plating is usually performed on the entire lead frame to prevent oxidation of the copper substrate during the plastic packaging process. However, this method has obvious shortcomings. Although the traditional full silver plating process can effectively prevent the oxidation of the copper substrate, it also leads to a large amount of silver resource waste, especially for non-functional areas. Silver plating is completely unnecessary, which adds unnecessary cost burden. From silver plating to final packaging molding, the traditional multi-step process makes the entire production cycle long and difficult to quickly respond to changes in market demand. Summary of the invention

[0005] In order to solve the problems of low process production efficiency and high cost in the prior art, the present application provides a roll-to-roll continuous electroplating process, which can be cut into strips for packaging through direct roll-to-roll anti-displacement - selective silver plating - selective tin plating, thereby saving the cost of important raw materials for pre-silver plating and full silver plating, reducing transportation costs, etc., simplifying the production process and improving production efficiency.

[0006] The present application provides a roll-to-roll continuous electroplating process, comprising the following steps:

[0007] S1. The lead frame strip is placed in a degreasing liquid for ultrasonic degreasing, then washed and dried with tap water, placed in a degreasing liquid again for electrolysis, and then washed and dried with tap water;

[0008] S2, immersing the lead frame material strip after electrolysis in an activation solution at room temperature for 5s-10s, and then washing and drying the lead frame material strip with deionized water, wherein the activation solution contains 20mL / L-40mL / L of sulfuric acid and 30g / L-50g / L of sodium persulfate;

[0009] S3, immersing the activated lead frame material strip in a pre-copper plating solution for 5s-15s, and then washing and drying the lead frame material strip with deionized water, wherein the pre-copper plating solution contains 30g / L-50g / L of copper ions and 20g / L-40g / L of potassium cyanide at a temperature of 45°C-55°C.;

[0010] S4, immersing the pre-copper-plated lead frame material strip into an anti-displacement liquid for 5s-15s, and then washing and drying the lead frame material strip with deionized water, wherein the anti-displacement liquid contains 15g / L-20g / L of anti-displacement salt, 30mL / L-35mL / L of anti-displacement agent, and 0.5g / L-1.5g / L of silver ions;

[0011] S5. The lead frame strip fully immersed in the anti-displacement liquid is partially silver plated in the functional area. The electrodeposition time is 2s-7s and the current density is 60A / dm 2 -120A / dm 2 , the thickness of the silver layer is 2μm-7μm, and then the lead frame strip is cleaned and dried with deionized water. The local silver plating electroplating solution contains 60g / L-80g / L silver, 2g / L-4g / L potassium cyanide, and a specific gravity of 16-24°Be'. The brightener opening cylinder content is 0.5mL / L-3mL / L, and the additive opening cylinder content is 1mL / L-5mL / L. The temperature is 55℃-65℃, and the pH value is 8.0-10.0; the brightener is added at 0.05mL / Ah-0.3mL / Ah, and the additive is added at 0.05mL / Ah-0.25mL / Ah;

[0012] S6. Electrolytically remove the silver from the lead frame strip that has been partially silver-plated. The electrodeposition time is 5s-15s and the current density is 2A / dm 2 -6A / dm 2 , use deionized water to clean and blow dry the lead frame strip after electrolytic desilvering, the desilvering solution contains 120g / L-180g / L of desilvering powder, 30g / L-50g / L of potassium hydroxide, the pH value is 8.0-13.0, and the temperature is room temperature;

[0013] S7, immersing the lead frame strip after the electrolytic desilvering in a silver protection solution for 5s-15s, washing and drying the lead frame strip after the electrolytic desilvering with deionized water, wherein the concentration of the silver protection solution is 2g / L-4g / L, and the temperature is 30°C-40°C;

[0014] S8, selectively tinning the lead frame strip that has completed silver protection. Before entering the selective tinning, the lead frame strip is turned 90 degrees to run vertically, and enters the single-side selective tinning tank for single-side selective tinning, and then moved out of the single-side selective tinning tank. The lead frame strip is turned 180 degrees and enters the single-side selective tinning tank for another single-side selective tinning, and then the lead frame strip after selective tinning is washed and dried with deionized water. The tinning solution is selected to have a stannous ion content of 40g / L-60g / L, a methylsulfonic acid content of 220g / L-280g / L, a brightener of 35mL / L-45mL / L, an auxiliary agent of 70mL / L-90mL / L, and a temperature of 5°C-20°C;

[0015] S9. The lead frame strip that has been selected for tin plating is immersed in a tin protection solution for 2s-6s, and the lead frame strip after tin protection is cleaned and dried with deionized water. The concentration of the tin protection agent is 60mL / L-140mL / L, the pH value is 2.2-3.2, and the temperature is 20℃-40℃;

[0016] S10, the lead frame strip that has completed tin protection is dried with a sponge, and then placed in a drying box for drying at a temperature of 120°C-150°C.

[0017] Furthermore, the ultrasonic degreasing time in step S1 is 10s-20s.

[0018] Furthermore, the current density of the electrolysis in step S1 is 10A / dm 2 -30A / dm 2 , the electrolysis time is 20s-40s.

[0019] Furthermore, the degreasing liquid in step S1 contains 100 g / L-160 g / L of degreasing powder, and the degreasing temperature is 55°C-65°C.

[0020] Furthermore, the pre-copper plating in step S3 adopts a current density of 2A / dm 2 -12A / dm 2 , the copper layer thickness is 0.05μm-0.25μm.

[0021] Furthermore, step S5 adopts the method of mold silver plating to position the lead frame strip that has been fully immersed in the anti-displacement liquid on the mold, and shield the non-functional area of ​​the lead frame strip, embed silicone in the non-functional area of ​​the lead frame strip, use ceramic nails to position the lead frame strip on the mold, and then use a press belt to put the lead frame strip on the mold. The press belt shields the non-functional area of ​​the lead frame strip, and the mold with the lead frame strip installed is placed in the electroplating solution for electroplating.

[0022] Furthermore, the step S8 of selecting the tinning process using a roll-to-roll electroplating wire strip flipping device comprises:

[0023] At least one washing tank, the washing tank is equipped with a guide wheel, the guide wheel is mirror-mounted on both sides of the washing tank, the guide wheel is used for flipping the material belt, the washing tank is mirror-mounted with a circular hole, the bottom of the washing tank is provided with a long groove, and the two ends of the long groove are provided with discharge ports. The guide wheel includes a wheel body, the wheel body is provided with a long strip opening, the wheel body is sleeved on the circular hole; a fixing ring is installed on the wheel body, and the wheel body is screwed and connected with the fixing ring. Rotating rods are installed on both sides of the guide wheel, and the rotating rods are used to rotate the guide wheel. The guide wheel can rotate at both ends of a washing tank, so that the material belt can complete a 90° angle change when passing through a washing tank. The guide wheel can rotate at both ends of a washing tank, so that the material belt can complete a 180° angle change when passing through three washing tanks. The length of the washing tank is 600cm. The rotating rod can be operated manually; or the rotating rod can be connected to a power device.

[0024] Furthermore, step S8 selects tin plating using an electrodeposition time of 80s-120s and a current density of 5A / dm 2 -20A / dm 2 , the thickness of the tin layer is 3μm-7μm.

[0025] The beneficial effects of this application are:

[0026] 1. In the general lead frame production process, the lead frame is first silver-plated continuously on a roll-to-roll basis, then cut into strips, debonded chips, bonded wires, packaged and formed, and finally the strip-packaged products are electroplated with tin and cut into single grains. This process has low production efficiency and high cost, and the non-functional area needs to be fully silver-plated to prevent copper oxidation during the plastic packaging process. The present application adopts direct roll-to-roll anti-displacement-selective silver plating-selective tin plating, and can be cut into strips for packaging, saving the cost of important raw materials for pre-silver plating and full silver plating, reducing transportation costs, etc., simplifying the production steps and improving production efficiency. The lead frame strip is subjected to ultrasonic degreasing and electrolytic treatment to remove surface grease and oxides to ensure good adhesion of subsequent coatings. Subsequently, the activation treatment carried out at room temperature enhances the surface activity of the substrate, providing ideal conditions for the subsequent electroplating process. In the pre-copper plating step, a thin and uniform copper film is formed on the lead frame using electrodeposition technology. This step not only enhances the conductivity of the material, but also provides a barrier to prevent oxidation of the copper substrate during the plastic packaging process. The introduction of anti-displacement liquid treatment effectively avoids accidental plating of non-functional areas and saves silver resources. Then, the partial silver plating of functional areas is achieved by mold positioning, which accurately meets the special needs of different parts and greatly reduces the use of silver. The electrolytic silver removal step further simplifies the silver layer, retaining only the necessary thickness to ensure good weldability and conductivity. The subsequent silver protection treatment increases the corrosion resistance of the coating.

[0027] 2. The tin plating is double-sided tin plating. The lead frame is vertically moved, and the tin plating area is controlled by adjusting the liquid level. One side is plated first, and then the other side is plated after passing through the reversing device in the middle. The roll-to-roll electroplating wire strip flipping device is used to realize the vertical operation of the lead frame and accurately control the tin plating area. The selective tin plating method of first one side and then the other side not only ensures the uniformity of the plating layer, but also eliminates the risk of missed plating caused by traditional shielding methods. Finally, after the tin protection liquid treatment, blotting and drying processes, the finished lead frame has excellent antioxidant ability and welding performance. Compared with the method of shielding the non-electroplating area and then fully immersing the electroplating, this operation method uses relatively simple equipment for electroplating, has no risk of missed plating, and has higher production efficiency.

[0028] 3. The roll-to-roll electroplating line material strip flipping device used in the present application can realize a 90° flip or 180° flip of the material strip, and can realize multi-sided process operations, ensuring that the material strip can be processed evenly, avoiding incomplete flipping or material damage, and is simple to operate, easy to adjust, and cost-saving, greatly improving work efficiency, achieving a smooth transition of the material strip during the flipping process, and avoiding deformation or damage caused by sudden twisting. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of a roll-to-roll electroplating wire strip flipping device for the present application;

[0030] Figure 2 This is a partial cross-sectional top view of a roll-to-roll electroplating wire strip flipping device of the present application;

[0031] Figure 3 This is a schematic diagram of the guide wheel structure of a roll-to-roll electroplating wire strip flipping device of the present application;

[0032] Figure 4 This is a schematic diagram of the combined structure of a roll-to-roll electroplating wire strip flipping device for the present application.

[0033] In the figure:

[0034] 1. Washing tank, 11. Circular hole, 12. Long groove, 13. Discharge port, 2. Guide wheel, 21. Wheel body, 2101. Long strip opening, 22. Fixed ring, 23. Rotating rod. DETAILED DESCRIPTION

[0035] Example 1

[0036] The present application provides a roll-to-roll continuous electroplating process, comprising the following steps:

[0037] S1. The lead frame strip is placed in the degreasing liquid for ultrasonic degreasing for 10 seconds, then washed and dried with tap water, and then placed in the degreasing liquid again for electrolysis with a current density of 10A / dm 2, the electrolysis time is 20s, then it is washed and dried with tap water, the degreasing liquid contains 100g / L of degreasing powder, and the degreasing temperature is 55℃;

[0038] S2, immersing the lead frame material strip after electrolysis in an activation solution at room temperature for 5 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the activation solution contains 20 mL / L sulfuric acid and 30 g / L sodium persulfate;

[0039] S3, the activated lead frame strip is immersed in a pre-copper plating solution, the electrodeposition time is 5s, and then the lead frame strip is washed and dried with deionized water, the pre-copper plating solution contains 30g / L copper ions, 20g / L potassium cyanide, the temperature is 45°C, and the current density is 2A / dm 2 , the copper layer thickness is 0.05μm;

[0040] S4, immersing the pre-copper-plated lead frame material strip into an anti-displacement liquid for 5 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the anti-displacement liquid contains 15 g / L of anti-displacement salt, 30 mL / L of anti-displacement agent, and 0.5 g / L of silver ions;

[0041] S5. Partially silver-plate the functional area of ​​the lead frame strip that has been fully immersed in the anti-displacement liquid, position the lead frame strip that has been fully immersed in the anti-displacement liquid on the mold by using a mold silver plating method, and shield the non-functional area of ​​the lead frame strip, embed silicone in the non-functional area of ​​the lead frame strip, use ceramic nails to position the lead frame strip on the mold, and then use a pressing belt to put the lead frame strip on the mold, the pressing belt shields the non-functional area of ​​the lead frame strip, and put the mold with the lead frame strip installed into the electroplating solution for electroplating; the electroplating time is 2s, and the current density is 60A / dm 2 , the silver layer thickness is 2μm, then the lead frame strip is cleaned and dried with deionized water, the local silver plating electroplating solution contains 60g / L silver, 2g / L potassium cyanide, specific gravity is 16°Be', brightener opening cylinder content is 0.5mL / L, additive opening cylinder content is 1mL / L, temperature is 55℃, pH value is 8.0; brightener is added at 0.05mL / Ah, additive is added at 0.05mL / Ah;

[0042] S6. Electrolytically remove the silver from the lead frame strip that has been partially silver-plated. The electrodeposition time is 5s and the current density is 2A / dm 2 , washing and drying the lead frame strip after electrolytic desilvering with deionized water, the desilvering solution contains 120g / L desilvering powder, 30g / L potassium hydroxide, pH value is 8.0, and the temperature is room temperature;

[0043] S7, immersing the lead frame strip after the electrolytic desilvering in a silver protection solution for 5 seconds, washing and drying the lead frame strip after the electrolytic desilvering with deionized water, wherein the concentration of the silver protection solution is 2 g / L and the temperature is 30° C.;

[0044] S8. The lead frame strip that has completed silver protection is selectively tinned. Before entering the selective tinning, the lead frame strip is turned 90° and moved vertically, and then enters the single-sided selective tinning tank for single-sided selective tinning. Then it is moved out of the single-sided selective tinning tank, and the lead frame strip is turned 180°, and enters the single-sided selective tinning tank for another single-sided selective tinning. The lead frame strip after selective tinning is then washed and dried with deionized water. The tinning solution is selected to have a stannous ion content of 40g / L, a methylsulfonic acid content of 220g / L, a brightener of 35mL / L, an auxiliary agent of 70mL / L, a temperature of 5°C, an electrodeposition time of 80s, and a current density of 5A / dm 2 , the thickness of the tin layer is 3μm;

[0045] S9. The lead frame strip that has been selected for tin plating is immersed in a tin protection solution for 2 seconds, and the lead frame strip after tin protection is cleaned and dried with deionized water. The concentration of the tin protection agent is 60 mL / L, the pH value is 2.2, and the temperature is 20°C.

[0046] S10, the lead frame strip that has completed tin protection is dried with a sponge, and then placed in a drying box for drying at a temperature of 120°C.

[0047] Example 2

[0048] S1. The lead frame strip is placed in the degreasing liquid for ultrasonic degreasing for 20 seconds, then cleaned and dried with tap water, and then placed in the degreasing liquid again for electrolysis, with a current density of 30A / dm 2 , the electrolysis time is 40s, then washed and dried with tap water, the degreasing liquid contains 160g / L of degreasing powder, and the degreasing temperature is 65℃;

[0049] S2, immersing the lead frame material strip after electrolysis in an activation solution at room temperature for 10 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the activation solution contains 40 mL / L sulfuric acid and 50 g / L sodium persulfate;

[0050] S3, the activated lead frame material strip is immersed in a pre-copper plating solution, the electrodeposition time is 15s, and then the lead frame material strip is washed and dried with deionized water, the pre-copper plating solution contains 50g / L copper ions, 40g / L potassium cyanide, the temperature is 55°C, and the current density is 12A / dm 2 , the copper layer thickness is 0.25μm;

[0051] S4, immersing the pre-copper-plated lead frame material strip into an anti-displacement liquid for 15 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the anti-displacement liquid contains 20 g / L of anti-displacement salt, 35 mL / L of anti-displacement agent, and 1.5 g / L of silver ions;

[0052] S5. Partially silver-plate the functional area of ​​the lead frame material strip that has been fully immersed in the anti-displacement liquid, position the lead frame material strip that has been fully immersed in the anti-displacement liquid on the mold by using a mold silver plating method, and shield the non-functional area of ​​the lead frame material strip, embed silicone in the non-functional area of ​​the lead frame material strip, use ceramic nails to position the lead frame material strip on the mold, and then use a pressing belt to put the lead frame material strip on the mold, the pressing belt shields the non-functional area of ​​the lead frame material strip, and put the mold with the lead frame material strip installed into the electroplating solution for electroplating; the electroplating time is 7s, and the current density is 120A / dm 2 , the silver layer thickness is 7μm, then the lead frame strip is cleaned and dried with deionized water, the local silver plating electroplating solution contains 80g / L silver, 4g / L potassium cyanide, specific gravity 24°Be', 3mL / L brightener opening cylinder content, 5mL / L additive opening cylinder content, temperature 65℃, PH value 10.0; brightener is added at 0.3mL / Ah, additive is added at 0.25mL / Ah;

[0053] S6: Electrolytically remove the silver from the lead frame strip that has been partially silver-plated. The electrodeposition time is 15 seconds and the current density is 6A / dm 2 , washing and drying the lead frame strip after electrolytic desilvering with deionized water, the desilvering solution contains 180g / L desilvering powder, 50g / L potassium hydroxide, the pH value is 13.0, and the temperature is room temperature;

[0054] S7, immersing the lead frame strip after the electrolytic desilvering in a silver protection solution for 15 seconds, washing and drying the lead frame strip after the electrolytic desilvering with deionized water, wherein the concentration of the silver protection solution is 4 g / L and the temperature is 40° C.;

[0055] S8. The lead frame strip that has completed silver protection is selectively tinned. Before entering the selective tinning, the lead frame strip is turned 90° and moved vertically, and then enters the single-sided selective tinning tank for single-sided selective tinning. Then it is moved out of the single-sided selective tinning tank, and the lead frame strip is turned 180°, and enters the single-sided selective tinning tank for another single-sided selective tinning. The lead frame strip after selective tinning is then washed and dried with deionized water. The tinning solution is selected to have a stannous ion content of 60g / L, a methylsulfonic acid content of 280g / L, a brightener of 45mL / L, an auxiliary agent of 90mL / L, a temperature of 20°C, an electroplating time of 120s, and a current density of 20A / dm 2 , the thickness of the tin layer is 7μm;

[0056] S9. The lead frame strip that has been selected for tin plating is immersed in a tin protection solution for 6 seconds, and the lead frame strip after tin protection is cleaned and dried with deionized water. The concentration of the tin protection agent is 140 mL / L, the pH value is 3.2, and the temperature is 40°C.

[0057] S10, the lead frame strip that has completed tin protection is dried with a sponge, and then placed in a drying box for drying at a drying temperature of 150°C.

[0058] Example 3

[0059] S1. The lead frame strip is placed in the degreasing liquid for ultrasonic degreasing for 15 seconds, then cleaned and dried with tap water, and then placed in the degreasing liquid again for electrolysis with a current density of 20A / dm 2 , the electrolysis time is 30s, then it is washed and dried with tap water, the degreasing liquid contains 130g / L of degreasing powder, and the degreasing temperature is 60℃;

[0060] S2, immersing the lead frame material strip after electrolysis in an activation solution at room temperature for 8 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the activation solution contains 30 mL / L sulfuric acid and 40 g / L sodium persulfate;

[0061] S3, the activated lead frame strip is immersed in a pre-copper plating solution, the electrodeposition time is 10s, and then the lead frame strip is washed and dried with deionized water, the pre-copper plating solution contains 40g / L copper ions, 30g / L potassium cyanide, the temperature is 50°C, and the current density is 8A / dm 2 , the copper layer thickness is 0.1μm;

[0062] S4, immersing the pre-copper-plated lead frame material strip into an anti-displacement liquid for 10 seconds, and then washing and drying the lead frame material strip with deionized water, wherein the anti-displacement liquid contains 18 g / L of anti-displacement salt, 33 mL / L of anti-displacement agent, and 1.0 g / L of silver ions;

[0063] S5. Partially silver-plate the functional area of ​​the lead frame material strip that has been fully immersed in the anti-displacement liquid, position the lead frame material strip that has been fully immersed in the anti-displacement liquid on the mold by using a mold silver plating method, and shield the non-functional area of ​​the lead frame material strip, embed silicone in the non-functional area of ​​the lead frame material strip, use ceramic nails to position the lead frame material strip on the mold, and then use a pressing belt to put the lead frame material strip on the mold, the pressing belt shields the non-functional area of ​​the lead frame material strip, and put the mold with the lead frame material strip installed into the electroplating solution for electroplating; the electroplating time is 5s, and the current density is 80A / dm 2, the silver layer thickness is 5μm, then the lead frame strip is cleaned and dried with deionized water, the local silver plating electroplating solution contains 70g / L silver, 3g / L potassium cyanide, specific gravity is 20°Be', brightener opening cylinder content is 2mL / L, additive opening cylinder content is 3mL / L, temperature is 60℃, pH value is 9.0; brightener is added at 0.15mL / Ah, additive is added at 0.15mL / Ah;

[0064] S6: Electrolytically remove the silver from the lead frame strip that has been partially silver-plated. The electrodeposition time is 10s and the current density is 4A / dm 2 , washing and drying the lead frame strip after electrolytic desilvering with deionized water, the desilvering solution contains 150g / L desilvering powder, 40g / L potassium hydroxide, the pH value is 11, and the temperature is room temperature;

[0065] S7, immersing the lead frame strip after the electrolytic desilvering in a silver protection solution for 10 seconds, washing and drying the lead frame strip after the electrolytic desilvering with deionized water, wherein the concentration of the silver protection solution is 3 g / L and the temperature is 35° C.;

[0066] S8. The lead frame strip that has completed silver protection is selectively tinned. Before entering the selective tinning, the lead frame strip is turned 90° and moved vertically, and then enters the single-sided selective tinning tank for single-sided selective tinning. Then it is moved out of the single-sided selective tinning tank, and the lead frame strip is turned 180°, and enters the single-sided selective tinning tank for another single-sided selective tinning. The lead frame strip after selective tinning is then washed and dried with deionized water. The tinning solution is selected to have a stannous ion content of 50g / L, a methylsulfonic acid content of 250g / L, a brightener of 40mL / L, an auxiliary agent of 80mL / L, a temperature of 15°C, an electroplating time of 100s, and a current density of 10A / dm 2 , the thickness of the tin layer is 5μm;

[0067] S9. The lead frame strip that has been selected for tin plating is immersed in a tin protection solution for 3 seconds, and the lead frame strip after tin protection is cleaned and dried with deionized water. The concentration of the tin protection agent is 110 mL / L, the pH value is 2.5, and the temperature is 30°C.

[0068] S10, the lead frame strip that has completed tin protection is dried with a sponge, and then placed in a drying box for drying at a temperature of 130°C.

[0069] The roll-to-roll electroplating wire strip flipping device used in step S8 in the above embodiment is as follows: Figure 1-4 As shown, it includes at least one water washing tank 1, the length of the water washing tank 1 is 600 cm, the water washing tank 1 is mirrored with a circular hole 11, a long groove 12 is provided at the bottom of the water washing tank 1, and discharge ports 13 are provided at both ends of the long groove 12. The liquid entering the water washing tank 1 passes through the long groove 12 and is discharged from the discharge port 13.

[0070] The washing tank 1 is equipped with guide wheels 2, which are mirror-mounted on both sides of the washing tank 1, and are used for flipping the material belt.

[0071] The guide wheel 2 includes a wheel body 21, and a long strip opening 2101 is provided on the wheel body 21. The wheel body 21 is sleeved on the circular hole 12. The design of the long strip opening 2101 can be optimized according to the thickness and width of the material belt to further improve the stability of the flipping.

[0072] Rotating rods 23 are installed on both sides of the guide wheel 2, and the rotating rods 23 are used to rotate the guide wheel 2. For the rotation of the guide wheel 2, in some embodiments, the rotation of the guide wheel 2 can be achieved by manually rotating the rotating rods 23. In other embodiments, the rotating rods 23 can be connected to a power device, such as a rotary cylinder, a hydraulic cylinder, a solenoid valve, etc. The power device drives the rotating rods 23, thereby driving the guide wheel 2 to rotate. The operating program of the power device can be integrated into the processing line of the roll-to-roll electroplating line strip, which can improve the flipping accuracy of the strip and the intelligence of the equipment, and integrate the flipping function with other process steps such as cleaning and drying to form a multifunctional processing unit, reducing the number of equipment and floor space.

[0073] The wheel body 21 is provided with a fixing ring 22, and the fixing ring 22 is used to fix or limit the position of the wheel body 21. The wheel body 21 is provided with threads, and the fixing ring 22 is also provided with threads, and the wheel body 21 and the fixing ring 22 are screwed together.

[0074] When the rotating rod 23 is rotated manually, when the rotating rod 23 drives the guide wheel 2 to rotate to a suitable position, the fixing ring 22 is tightened to fix and lock the guide wheel 2. When the rotating rod 23 is driven by a power device, the fixing ring 22 is screwed to a suitable position and is only used to limit the displacement of the guide wheel 2. The guide wheel 2 can rotate freely in the circular hole 12, so that the power device drives the rotating rod 23 to drive the guide wheel 2 to rotate.

[0075] A roll-to-roll electroplating line material strip flipping device has a flipping function. In some embodiments, the guide wheel 2 can rotate at both ends of a water washing tank 1, so that the material strip can complete a 90° angle change when passing through a water washing tank 1. Specifically, the material strip is introduced from the long strip opening 2101 of the guide wheel 2 at one end of the water washing tank 1, and is led out from the long strip opening 2101 of the guide wheel 2 at the other end of the water washing tank 1. The guide wheel 2 at the other end of the water washing tank 1 is rotated by the rotating rod 23 until the relative angle with the guide wheel 2 at one end of the water washing tank 1 is 90° different. At this time, the direction of the material strip has changed by 90°, but it still remains flat without obvious twisting. The flipped material strip enters the next working position.

[0076] In other embodiments, Figure 4 As shown, the guide wheel 2 can rotate at both ends of a washing tank 1, so that the material belt can complete a 180° angle change when passing through three washing tanks 1. Specifically, the material belt is introduced into the long strip opening 2101 of the guide wheel 2 at one end of the first washing tank 1, and the guide wheel 2 at the other end of the first washing tank 1 is rotated by the rotating rod 23 until the relative angle with the guide wheel 2 at one end of the first washing tank 1 is 45° different. The material belt is led out from the long strip opening 2101 of the guide wheel 2 at the other end of the first washing tank 1, and the material belt is introduced into the long strip opening 2101 of the guide wheel 2 at one end of the second washing tank 1. The rotation angle of the guide wheel 2 at one end of the second washing tank 1 is 45° different from the rotation angle of the guide wheel 2 at the other end of the first washing tank 1. The guide wheel 2 at the end is rotated by the rotating rod 23 until the relative angle with the guide wheel 2 at one end of the second washing tank 1 is 45° different. The material belt is led out from the long strip opening 2101 of the guide wheel 2 at the other end of the second washing tank 1, and the material belt is introduced into the long strip opening 2101 of the guide wheel 2 at one end of the third washing tank 1. The rotation angle of the guide wheel 2 at one end of the third washing tank 1 is 45° different from the rotation angle of the guide wheel 2 at the other end of the second washing tank 1. The guide wheel 2 at the other end of the third washing tank 1 is rotated by the rotating rod 23 until the relative angle with the guide wheel 2 at one end of the third washing tank 1 is consistent. At this time, by adjusting the guide wheels 2 in the three washing tanks 1, the material belt completes a 180° flip when passing through the three washing tanks. The distance between each washing tank and the angle adjustment of the guide wheels are carefully designed to ensure that the material belt gradually changes direction during the flipping process to avoid sudden twisting or deformation.

Claims

1. A roll-to-roll continuous electroplating process, characterized in that: The following steps are involved: S1. The lead frame strip is placed in a degreasing liquid for ultrasonic degreasing, then washed and dried with tap water, placed in a degreasing liquid again for electrolysis, and then washed and dried with tap water; S2, immersing the lead frame material strip after electrolysis in the activation solution at room temperature for 5s-10s, and then washing and drying the lead frame material strip with deionized water; S3, immersing the activated lead frame strip into a pre-copper plating solution for an electrodeposition time of 5s-15s, and then washing and drying the lead frame strip with deionized water; S4, immersing the pre-copper-plated lead frame material strip into the anti-displacement liquid for 5s-15s, and then washing and drying the lead frame material strip with deionized water; S5. The lead frame strip fully immersed in the anti-displacement liquid is partially silver plated in the functional area. The electrodeposition time is 2s-7s and the current density is 60A / dm 2 -120A / dm 2 , the thickness of the silver layer is 2μm-7μm, and then the lead frame strip is cleaned and dried with deionized water; S6, electrolytically desilvering the lead frame material strip that has been partially silver-plated, the electrodeposition time is 5s-15s, the current density is 2A / dm2-6A / dm2, and the lead frame material strip after electrolytic desilvering is cleaned and dried with deionized water; S7, immersing the lead frame strip after the electrolytic desilvering in a silver protection solution for 5s-15s, and washing and drying the lead frame strip after the electrolytic desilvering with deionized water; S8, selectively tinning the lead frame strip that has completed silver protection. Before entering the selective tinning, the lead frame strip is turned 90 degrees to run vertically, enters the single-side selective tinning tank for single-side selective tinning, and then moves out of the single-side selective tinning tank. The lead frame strip is turned 180 degrees and enters the single-side selective tinning tank for another single-side selective tinning, and then the lead frame strip after selective tinning is cleaned and dried with deionized water; S9, immersing the lead frame material strip that has been selected for tin plating in a tin protection liquid for 2s-6s, and washing and drying the lead frame material strip after tin protection with deionized water; S10, the lead frame strip that has completed tin protection is dried with a sponge and then placed in a drying box for drying.

2. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: The ultrasonic degreasing time in step S1 is 10s-20s.

3. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: The current density of the electrolysis in step S1 is 10A / dm 2 -30A / dm 2 , the electrolysis time is 20s-40s.

4. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: The degreasing liquid in step S1 contains 100 g / L-160 g / L of degreasing powder, and the degreasing temperature is 55°C-65°C.

5. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: The pre-copper plating in step S3 adopts a current density of 2A / dm 2 -12A / dm 2 , the copper layer thickness is 0.05μm-0.25μm.

6. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: Step S5 adopts the method of mold silver plating to position the lead frame material strip that has been fully immersed in the anti-displacement liquid on the mold, and shield the non-functional area of ​​the lead frame material strip, embed silica gel in the non-functional area of ​​the lead frame material strip, use ceramic nails to position the lead frame material strip on the mold, and then use a pressing belt to put the lead frame material strip on the mold. The pressing belt shields the non-functional area of ​​the lead frame material strip, and the mold with the lead frame material strip installed is placed in the electroplating solution for electroplating.

7. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: Step S8 selects tin plating with an electrodeposition time of 80s-120s and a current density of 5A / dm 2 -20A / dm 2 , the thickness of the tin layer is 3μm-7μm.

8. The roll-to-roll continuous electroplating process according to claim 1, characterized in that: The step S8 of selecting tinning by using a roll-to-roll electroplating wire strip flipping device comprises: At least one water washing tank (1), the water washing tank (1) is equipped with guide wheels (2), the guide wheels (2) are mirror-mounted on both sides of the water washing tank (1), and the guide wheels (2) are used for flipping the material belt.

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