A method for reducing COD emissions in integrated circuit tinning production process

Abstract

A method for reducing COD emissions in an integrated circuit tinning production process belongs to the technical field of integrated circuit wastewater treatment. The present invention comprises the following steps: taking out a lead frame immersed in a mother tank, and vertically setting it above the mother tank for dripping; after dripping, soaking the lead frame in a pure water tank filled with pure water, so that the de-glue solution attached to the lead frame is dissolved in the pure water; after soaking in pure water, taking the lead frame out of the pure water tank, and soaking it in a plurality of cleaning tanks filled with cleaning water in turn for washing; in the pure water tank, when the concentration of the working liquid formed by the de-glue solution being dissolved in pure water reaches saturation, it is recovered and added to the de-glue solution in the mother tank, and the pure water is volatilized by heating. The present invention dissolves the de-glue solution attached to the lead frame in pure water by adding a pure water dissolution process, thereby reducing the concentration of the de-glue solution during subsequent washing with cleaning water, thereby reducing COD emissions.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuit wastewater treatment, and in particular relates to a method for reducing COD emissions in an integrated circuit tinning production process. Background Art

[0002] After the lead frame is epoxy encapsulated, there will be excess glue left on the lead pins and heat sink, which needs to be removed before the subsequent pure tin electroplating. The main methods for removing excess glue are currently chemical solution immersion, electrolysis and mechanical methods. The mechanical method is rarely used now because the spray medium used will damage the substrate. The electrolysis method is greatly limited because the electrolysis voltage or current is too high, which will damage the chip and cause stratification, and it cannot remove some serious excess glue. The chemical solution immersion method dissolves or softens and loosens the excess glue through chemical action, and then combines it with subsequent high-pressure water jet spraying to cleanly and thoroughly remove the excess glue. This method can be applied to lead frames of almost all types after encapsulation, and is currently the mainstream method for removing excess glue in the industry.

[0003] At present, in the chemical solution immersion method, a de-glue solution is often used to remove the overflowed glue. Generally, multiple lead frames are stacked in sequence and loaded into a cleaning rack, and the cleaning rack loaded with the lead frames is immersed in the mother tank of an immersion machine for de-glue treatment. The mother tank is filled with the de-glue solution. After immersion, the lead frames are immersed in multiple cleaning tanks of the immersion machine in sequence for water cleaning to remove the de-glue solution attached to the surface of the lead frame and in the gap between two adjacent stacked lead frames.

[0004] Since the overflow glue removal solution (such as SYD-711 solution) contains a large amount of COD, generally 1 million mg / L, the COD content in the wastewater formed after the lead frame water washing is relatively high, generally 1500 mg / L, far exceeding the COD discharge standard (generally 200 mg / L). If the COD content in the wastewater is to be reduced, the number of lead frame water washings needs to be increased, which will increase the use of washing water, increase the discharge of wastewater, cause water resource waste, and increase enterprise costs. Summary of the invention

[0005] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a method for reducing COD emissions in the integrated circuit tinning production process.

[0006] The above technical problem of the present invention is mainly solved by the following technical solution: A method for reducing COD emissions in an integrated circuit tinning production process comprises the following steps:

[0007] Step S1, taking out the lead frame immersed in the master groove, and vertically setting it above the master groove for dripping, so that the overflow glue removal solution attached to the lead frame drips back into the master groove;

[0008] Step S2, after dripping, immersing the lead frame in a pure water tank filled with pure water, so that the excess glue removal solution attached to the lead frame is dissolved in the pure water;

[0009] Step S3, after being soaked in pure water, taking the lead frame out of the pure water tank, and soaking it in a plurality of cleaning tanks filled with cleaning water in turn for water washing;

[0010] Step S4, in the pure water tank, when the concentration of the working solution formed by dissolving the overflow glue removal solution in pure water reaches saturation, it is recovered and added to the overflow glue removal solution in the mother tank, and the pure water is volatilized by heating.

[0011] Preferably, a plurality of the lead frames are vertically arranged in sequence and loaded into the cleaning rack.

[0012] Preferably, in step S3, four cleaning tanks are provided, and waste water is generated after the lead frame is cleaned with water.

[0013] Preferably, in step S4, the heating temperature is 110±5°C.

[0014] Preferably, in step 2, a mounting platform is installed at the bottom of the pure water tank, a driving motor is installed on the lower surface of the mounting platform, the output end of the driving motor passes through the mounting platform and is connected to an eccentric wheel, sliding blocks are symmetrically arranged on both sides of the eccentric wheel on the mounting platform, the eccentric wheel can respectively abut one side of the sliding block on both sides and drive the sliding block to move toward the other side of the sliding block, a guide rod is installed on the other side of the sliding block, a moving block is installed on the end of the guide rod, a guide sleeve and a first spring are sleeved on the guide rod, and the first spring is located between the sliding block and the guide sleeve, a support rod is installed on the inner side of the moving block, and the end of the support rod passes through the wall of the pure water tank and is connected to a push plate; a support platform is installed on the top of the pure water tank, the support platform is hinged with a suspension arm through a hinge seat, a fixed block is provided on the support platform, the fixed block is connected to one end of the suspension arm through a second spring, one end of the suspension arm is hinged with a connecting rod, the end of the connecting rod is hinged to the top of one of the moving blocks, and the other end of the suspension arm is provided with a hook.

[0015] Preferably, a winch is provided on the boom, and a steel wire rope on the winch is connected to the hook.

[0016] Preferably, the other end of the boom is provided with an adjusting sleeve, a pulley is mounted on the adjusting sleeve, and the steel wire rope passes through the pulley and is connected to the hook.

[0017] The present invention has the beneficial effects as follows: the present invention adds a pure water dissolution process after the lead frame is soaked in a de-glue solution, so that the de-glue solution attached to the lead frame is dissolved in pure water, thereby reducing the concentration of the de-glue solution during subsequent washing with cleaning water, thereby reducing COD emissions; at the same time, when the concentration of the working fluid formed by the de-glue solution being dissolved in pure water reaches saturation, it can be added to the mother tank for use, and the pure water can be volatilized by heating to leave the de-glue solution dissolved in pure water. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a pure water tank of the present invention;

[0019] Figure 2 It is a structural schematic diagram of the mounting platform of the present invention;

[0020] Figure 3 It is a structural schematic diagram of the cleaning rack of the present invention.

[0021] In the figure: 1. pure water tank; 2. mounting table; 3. driving motor; 4. eccentric wheel; 5. sliding block; 6. guide rod; 7. moving block; 8. first spring; 9. guide sleeve; 10. support rod; 11. push plate; 12. support table; 13. hinge seat; 14. boom; 15. connecting rod; 16. hook; 17. winch; 18. adjusting sleeve; 19. bolt; 20. pulley; 21. cleaning rack; 22. top plate; 23. bottom plate; 24. left plate; 25. right plate; 26. fixing rod; 27. lead frame; 28. slot; 29. ​​second spring; 30. fixing block. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0023] Embodiment: A method for reducing COD emissions in an integrated circuit tinning production process comprises the following steps:

[0024] Step S1, immersing the lead frame 27 in a master tank containing a de-glue solution, the de-glue solution is a SYD-711 solution, after immersion, taking the lead frame 27 out of the master tank, and vertically setting it above the master tank for dripping, the dripping time is 90 seconds, so that the de-glue solution attached to the lead frame 27 drips back into the master tank;

[0025] Step S2, after dripping, immersing the lead frame 27 in a pure water tank 1 filled with pure water, so that the excess glue removal solution attached to the lead frame 27 is dissolved in the pure water, wherein the pure water is the solvent and the excess glue removal solution is the solute;

[0026] Step S3, after being soaked in pure water, the lead frame 27 is taken out from the pure water tank 1, and then sequentially soaked in a plurality of cleaning tanks filled with cleaning water for washing, and the cleaning water can be tap water;

[0027] Step S4, in the pure water tank 1, when the concentration of the working solution formed by dissolving the overflow glue removal solution in pure water reaches saturation, it is recovered and added to the overflow glue removal solution in the mother tank, and the pure water is volatilized by heating.

[0028] In step S1, a plurality of lead frames 27 are arranged vertically in sequence and loaded in the cleaning rack 21. When soaking, the cleaning rack 21 loaded with the lead frames 27 is soaked in the mother tank. When dripping, the lead frames 27 are arranged vertically so that the glue removal solution attached to the lead frames 27 drips downward due to gravity and drips back into the mother tank.

[0029] The dripping time can be adjusted and set according to the adhesion of the de-glue solution on the lead frame 27 and the loading capacity of the lead frame 27, so that the de-glue solution attached to the surface of the lead frame 27 can be dripped back into the mother groove as much as possible. On the one hand, the de-glue solution can be dripped back for utilization, and on the other hand, the amount of de-glue solution attached to the lead frame 27 can be reduced to reduce the amount of de-glue solution dissolved in pure water at a single time, thereby improving the utilization rate of pure water and reducing the concentration of the de-glue solution in the cleaning water.

[0030] In step S4, when the concentration of the working solution formed by dissolving the overflow glue removal solution in pure water reaches saturation, it can be added to the mother tank in batches, and the addition amount of each batch can be controlled to avoid excessive addition that will dilute the overflow glue removal solution and affect the overflow glue removal effect of the lead frame 27.

[0031] In the process of removing the overflow glue from the lead frame 27, a heater is provided in the master tank, and the heating temperature is 110±5°C. On the one hand, the effect of removing the overflow glue from the lead frame 27 is improved by heating, and on the other hand, the solvent pure water in the added working liquid is volatilized by heating, leaving the solute in the working liquid, that is, the overflow glue removal solution dissolved in pure water. After the solute is mixed with the overflow glue removal solution in the master tank, it is used for overflow glue removal. Since pure water does not contain any impurities, when the pure water evaporates, only the solute (that is, the overflow glue removal solution) is left, and the use of the solute has no effect, and can be mixed with the overflow glue removal solution in the master tank for use.

[0032] In step 2, the glue removal solution on the lead frame 27 is dissolved in pure water by immersion. To improve the dissolution efficiency and dissolution effect, the structure of the pure water tank 1 is optimized, specifically:

[0033] like Figure 1 , Figure 2As shown, a mounting platform 2 is installed at the bottom of the pure water tank 1, and a driving motor 3 is installed on the lower surface of the mounting platform 2. The output end of the driving motor 3 passes through the mounting platform 2 and extends to the top of the mounting platform 2, and the output end of the driving motor 3 is connected to an eccentric wheel 4. Sliding blocks 5 are symmetrically arranged on both sides of the eccentric wheel 4 on the mounting platform 2. There are two sliding blocks 5. The sliding blocks 5 are slidably connected to the mounting platform 2. The sliding blocks 5 can be slidably connected to the mounting platform 2 by using guide rails, or sliding grooves and sliders. The eccentric wheel 4 can respectively abut one side of the sliding blocks 5 on both sides and drive the sliding blocks 5 to move toward the other side of the sliding blocks 5. A guide rod 6 is installed at the other end of the sliding block 5, and the end of the guide rod 6 extends to the outside of the mounting platform 2 and is installed with a moving block 7. A guide sleeve 9 and a first spring 8 are sleeved on the guide rod 6, and the guide sleeve 9 is fixedly connected to the mounting platform 2. The first spring 8 is located between the sliding block 5 and the guide sleeve 9, and one end of the first spring 8 abuts against the other side of the sliding block 5, and the other end of the first spring 8 abuts against the inner side of the guide sleeve 9. A support rod 10 is installed on the inner side of the moving block 7, and the end of the support rod 10 passes through the groove wall of the pure water tank 1 and extends into the pure water tank 1, and the end of the support rod 10 is connected to a push plate 11.

[0034] A support platform 12 is installed on the top of the pure water tank 1, and a hinged seat 13 is installed on the upper surface of the support platform 12. The hinged seat 13 is hinged with a boom 14, and a fixed block 30 is installed on the upper surface of the support platform 12. A second spring 29 is installed on the fixed block 30, and the end of the second spring 29 is connected to one end of the boom 14. A connecting rod 15 is hinged at one end of the boom 14, and the end of the connecting rod 15 is hinged to the top of one of the moving blocks 7. A winch 17 is provided on the boom 14, and a steel wire rope on the winch 17 is connected to a hook 16 below the other end of the boom 14, and the hook 16 is used to hang a cleaning rack 21.

[0035] When in use, the driving motor 3 drives the eccentric wheel 4 to rotate, and the eccentric wheel 4 can respectively contact with the sliding blocks 5 on both sides, and drive the sliding blocks 5 on both sides to move toward the other side, specifically:

[0036] When the eccentric wheel 4 contacts one end of the sliding block 5 on the left, it can push the sliding block 5 on the left to move to the left. The sliding block 5 on the left pushes the moving block 7 on the left to move to the left through the guide rod 6. The first spring 8 is compressed, and the moving block 7 on the left drives the push plate 11 on the left to move to the left through the support rod 10. The push plate 11 on the left pushes the pure water in the pure water tank 1 to flow to the left.

[0037] When the eccentric wheel 4 is not in contact with one end of the left sliding block 5, the left sliding block 5 moves to the right under the elastic force of the first spring 8, and the left sliding block 5 pushes the left moving block 7 to move to the right through the guide rod 6, and the left moving block 7 drives the left push plate 11 to move to the right through the support rod 10, and the left push plate 11 pushes the pure water in the pure water tank 1 to flow to the right;

[0038] When the eccentric wheel 4 rotates to the right sliding block 5 and contacts one end of the right sliding block 5, it can push the right sliding block 5 to move to the right, and the right sliding block 5 pushes the right moving block 7 to move to the right through the guide rod 6. The first spring 8 is compressed, and the right moving block 7 drives the right push plate 11 to move to the right through the support rod 10, and the right push plate 11 pushes the pure water in the pure water tank 1 to flow to the right; at the same time, the right moving block 7 moves one end of the suspension arm 14 downward through the connecting rod 15 to make the suspension arm 14 horizontal, thereby moving the cleaning rack 21 loaded with the lead frame 27 upward;

[0039] When the eccentric wheel 4 is not in contact with one end of the sliding block 5 on the right, the sliding block 5 on the right moves toward the left under the elastic force of the first spring 8, and the sliding block 5 on the right pushes the moving block 7 on the right to move to the left through the guide rod 6. The moving block 7 on the right drives the push plate 11 on the right to move to the left through the support rod 10, and the push plate 11 on the right pushes the pure water in the pure water tank 1 to flow to the left; at the same time, the moving block 7 on the right lifts one end of the suspension arm 14 through the connecting rod 15, so that the other end of the suspension arm 14 moves downward, thereby moving the cleaning rack 21 loaded with the lead frame 27 downward.

[0040] The driving motor 3 drives the eccentric wheel 4 to rotate, and the eccentric wheel 4 drives the sliding blocks 5 on both sides to move back and forth respectively. The sliding blocks on both sides drive the push plate 11 to move back and forth through their corresponding guide rods 6, moving blocks 7 and support rods 10. The pure water flows back and forth under the push of the push plate 11, thereby realizing the back and forth flushing of the lead frame 27 in the cleaning rack 21, and accelerating the dissolution of the excess glue removal solution attached to the lead frame 27 in the pure water; at the same time, the right moving block 7 makes one end of the suspension arm 14 reciprocately lift and move down through the connecting rod 15, so that the cleaning rack 21 suspended on the other side of the suspension arm 14 moves up and down reciprocally, so that the lead frame 27 is disturbed by the reciprocating pure water, and some gap areas on the lead frame 27 are flushed by the disturbance, so that the excess glue removal solution attached to the lead frame 27 is dissolved in the pure water; by flushing the lead frame 27 left and right and up and down, a large amount of excess glue removal solution attached to the lead frame 27 is dissolved in the pure water, thereby improving the dissolution effect and dissolution efficiency of the excess glue removal solution.

[0041] Preferably, the other end of the boom 14 is sleeved with an adjustment sleeve 18, on which a pulley 20 is mounted, and the wire rope on the winch 17 passes through the pulley 20 and is connected to the hook 16. The adjustment sleeve 18 is threadedly connected with a bolt 19, and is fixed to the boom 14 by the bolt 19 abutting against the surface of the boom 14. By changing the position of the adjustment sleeve 18 on the boom 14, the balance of the boom 14 can be adjusted to make the boom 14 level.

[0042] As a preference, Figure 3 As shown, the top plate 22, the bottom plate 23, the left plate 24 and the right plate 25 of the cleaning rack 21 are evenly provided with a plurality of through holes (not shown), the front and rear sides of the cleaning rack 21 are open, and the left plate 24 and the right plate 25 are connected by a fixing rod 26. When the cleaning rack 21 is immersed in the pure water of the pure water tank 1, the front and rear sides of the cleaning rack 21 are respectively facing the push plates 11 on both sides, so that the pure water can flush the surface of each lead frame 27. A slot 28 is provided on the bottom plate 23 of the cleaning rack 21. By providing the slot 28, on the one hand, the lead frame 27 can be arranged vertically; on the other hand, the distance between two adjacent lead frames 27 can be increased, so that the pure water can flow through the surface of the lead frame 27, increase the contact area between the pure water and the surface of the lead frame 27, and avoid the situation where the lead frame 27 is stacked and the de-glue solution remains in the gap.

[0043] By adding a pure water dissolution process after the lead frame 27 is soaked in the de-glue solution, a large amount of the de-glue solution attached to the lead frame 27 is dissolved in the pure water, so that a large amount of COD is dissolved in the pure water, thereby reducing the concentration of the de-glue solution in the subsequent washing with cleaning water, reducing the number of washing times with cleaning water, and reducing the amount of cleaning water used. In the wastewater formed after washing, the concentration of the de-glue solution is low and the COD content is low, thereby reducing the COD emission and making it meet the emission standards.

[0044] In this embodiment, by adding a pure water dissolution process, the lead frame can be washed with water four times to meet the COD emission standard. For specific data, see Table 1; accordingly, four cleaning tanks are set to soak and wash the lead frame in turn.

[0045] Table 1 Comparison of COD content in wastewater

[0046]

[0047] From the above, it can be seen that by adding a pure water dissolution process after the lead frame is immersed in the overflow glue removal solution, the COD content in the wastewater is greatly reduced, and the COD discharge is reduced.

[0048] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to belong to the protection scope of the present invention.

Claims

1. A method for reducing COD emissions in an integrated circuit tinning production process, characterized in that: The steps include: Step S1, taking out the lead frame (27) immersed in the mother groove, and vertically setting it above the mother groove for dripping, so that the overflow glue removal solution attached to the lead frame (27) drips back into the mother groove; Step S2, after dripping, immersing the lead frame (27) in a pure water tank (1) filled with pure water, so that the excess glue removal solution attached to the lead frame (27) is dissolved in the pure water; Step S3, after being soaked in pure water, the lead frame (27) is taken out from the pure water tank (1), and sequentially soaked in a plurality of cleaning tanks containing cleaning water for water washing; Step S4, in the pure water tank (1), when the concentration of the working solution formed by dissolving the overflow glue removal solution in pure water reaches saturation, the working solution is recovered and added to the overflow glue removal solution in the mother tank, and the pure water is volatilized by heating; In step S3, four cleaning tanks are provided, and the lead frame (27) is washed with water to form waste water; In step S4, when the concentration of the working solution formed by dissolving the overflow glue removal solution in pure water reaches saturation, it can be added to the mother tank in batches, and the amount of each batch added is controlled to avoid diluting the overflow glue removal solution due to excessive addition; A plurality of lead frames (27) are vertically arranged in sequence and loaded into a cleaning rack (21); In step S4, the heating temperature is 110±5°C; In step S2, a mounting platform (2) is installed at the bottom of the pure water tank (1), a driving motor (3) is installed on the lower surface of the mounting platform (2), the output end of the driving motor (3) passes through the mounting platform (2) and is connected to an eccentric wheel (4), sliding blocks (5) are symmetrically arranged on both sides of the eccentric wheel (4) on the mounting platform (2), the eccentric wheel (4) can respectively abut one side of the sliding blocks (5) on both sides and drive the sliding blocks (5) to move toward the other side of the sliding blocks (5), a guide rod (6) is installed on the other side of the sliding block (5), a moving block (7) is installed at the end of the guide rod (6), a guide sleeve (9) and a first spring (8) are sleeved on the guide rod (6), and the first spring (8) is positioned A support rod (10) is installed on the inner side of the moving block (7) between the sliding block (5) and the guide sleeve (9), and the end of the support rod (10) passes through the wall of the pure water tank (1) and is connected to a push plate (11); a support platform (12) is installed on the top of the pure water tank (1), and the support platform (12) is hinged to a suspension arm (14) through a hinge seat (13), and a fixed block (30) is provided on the support platform (12), and the fixed block (30) is connected to one end of the suspension arm (14) through a second spring (29), and one end of the suspension arm (14) is hinged to a connecting rod (15), and the end of the connecting rod (15) is hinged to the top of one of the moving blocks (7), and the other end of the suspension arm (14) is provided with a hook (16); The top plate (22), the bottom plate (23), the left side plate (24) and the right side plate (25) of the cleaning rack (21) are all provided with a plurality of through holes. The front side and the rear side of the cleaning rack (21) are open, and the left side plate (24) and the right side plate (25) are connected by a fixing rod (26). When the cleaning rack (21) is immersed in pure water in the pure water tank (1), the front side and the rear side of the cleaning rack (21) face the push plates (11) on both sides respectively, and a slot (28) is provided on the bottom plate (23) of the cleaning rack (21).

2. The method for reducing COD emissions in an integrated circuit tinning production process according to claim 1, characterized in that: A hoist (17) is provided on the boom (14), and a steel wire rope on the hoist (17) is connected to a hook (16).

3. The method for reducing COD emissions in an integrated circuit tinning production process according to claim 2, characterized in that: The other end of the boom (14) is sleeved with an adjustment sleeve (18), a pulley (20) is installed on the adjustment sleeve (18), and the steel wire rope passes through the pulley (20) and is connected to the hook (16).

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