SMT Repair Operation Standard

I. Solder Paste Board Repair Specification

2. Repair Tools

Soldering tools are essential for solder repair work. Correct selection and proficient mastery of their functions and usage are very helpful for improving soldering skills.

Tools: Soldering iron, solder wire, rosin, hot air gun

3. Auxiliary Tools Used for IC Soldering Repair

Inspection gauge, cleaning solvent, brush, lint-free cloth, soldering iron tip, soldering iron tip cleaning station.

7. Pre-operation Checks

①. Confirm that the solder wire used for repair is within its expiry date. The shelf life is 2 years.

②. Confirm that the solder wire is the specified environmentally friendly solder wire.

③. Wear and check the electrostatic wrist strap (3 times/day).

④. Clean the soldering iron tip and perform necessary tinning maintenance.

⑤. Do not let the soldering iron tip contact the repair area for too long (may cause component breakage or damage).

⑥. When repairing, first contact the soldering iron tip to the repair area to raise its temperature, then apply the solder wire.

9. Repair Procedure for Solder Paste Products

Using a Soldering Iron

1. Locate the position of the defective product and the type of defect. There is a defect label, but keep the defect label until step 4.

2. Adjust the soldering iron temperature according to the repair item and component.

3. First, heat the repair area with the soldering iron (preheat for 1–2 seconds to reduce solder splatter).

4. Apply solder wire to the repair area.

5. Remove the solder wire once the solder has fully melted.

6. Remove the soldering iron tip 1–2 seconds after removing the solder wire. Keep the defect label on the repaired position for all repaired products.

7. Check the solder joint quality. It should be shiny, bright, and smooth, without causing secondary defects to surrounding components.

8. After passing inspection, fill out the repair record form.

9. After repairing all defective lots, sort and pack them separately, and attach a product identification label.

10. Place into the designated input slot and hand over to the appearance inspector for re-inspection.

11. 

When Using a Hot Air Gun to Remove Components

1. If using a hot air gun to remove components from solder paste products, adjust the temperature appropriately: 300–330°C for single-sided boards, 350–380°C for double-sided boards.

2. Use the nozzle of the hot air gun to heat the component to be removed by moving it evenly back and forth. Control the heating time: 2–3 seconds for single-sided boards, 3–5 seconds for double-sided boards, until the solder is fully melted.

When removing multi-pin ICs, the time may be longer, but carefully observe changes in the component and copper pad. If discoloration, burning/blistering is found, stop the operation.

3. Remove the component with tweezers, then move the hot air gun nozzle away.

4. 

II. Red Glue Board Repair Specification

3. Repair Procedure for Red Glue Boards

1. Locate the position of the defective product and the type of defect. There is a defect label, but keep the defect label until step 4.

2. Use a hot air gun to heat the area to be repaired (280–300°C). For CHIP components, heat for 3–5 seconds; for non-CHIP components, adjust according to component size. Then use tweezers to remove the defective component. If the removed component is a CHIP component, it may be broken, so all such removed components shall be discarded.

3. Use the hot air gun to heat the red glue, then use a scraper (homemade from the edge of the board) to scrape off the red glue.

4. Apply new adhesive (as specified by the customer) at the position where the old adhesive was removed.

5. Place the correct component onto the repair area using tweezers (pay attention to polarity for polarized components).

6. Self-inspect the repaired area and its surroundings for secondary defects. Compare with a good component or sample to confirm there is no adhesive overflow or red glue contamination on the solder pads. Fill out the repair record and apply high-temperature tape marked with the repair location.

7. After repairing all defective lots, sort and pack them separately, and attach a product identification label.

8. Place into the reflow oven. Before and after loading, notify the post-reflow visual inspector to follow up on quantity and conduct focused inspections.

9. Pack separately and send to QA for inspection. The high-temperature tape indicating the repair location can only be removed after QA has passed the inspection.

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3. Method for Cleaning Repaired Pins

3.1 Tools Used:

A. Brush: Used to clean rosin/solder residue from the repaired area.

B. Cleaner (Shachihata brand): Used to dissolve rosin and its附着物.

C. Lint-free cloth: Used to wipe away the dissolved rosin and residual cleaner.

3.2 Cleaning Steps:

A. Apply a small amount of cleaning liquid to the brush. Do not apply directly onto the IC to avoid excessive liquid that may dry slowly inside the IC.

B. Brush the brush parallel to the pins, inward, mainly to remove residual foreign matter between the pins.

C. Gently wipe away the dissolved rosin with a lint-free cloth.