SMT Processing Company Welding Paste Control & Usage Operating Specifications

Pcbandassembly SMT Processing Company Welding Paste Control & Use Operation Specifications

Responsibilities

Production: welding paste collection, rewarming, mixing, use, scrapping, empty bottle and expired welding paste recycling, refrigerator temperature inspection.
Quality: welding paste collection, rewarming, mixing, use, scrapping, refrigerator temperature audit confirmation.

Work Content

• Storage

1) The production team leader is entrusted with the responsibility of placement. The welding paste collected from the warehouse in the refrigerator in layers according to the serial number.

2) The welding paste that needs to be tried should be placed in the special compartment of the storage refrigerator. The welding paste brand, factory entry date, expiration date, and “trial” should be marked on the trial welding paste can.

3) When storing the welding paste in the refrigerator, it’s best to arrange it from inside to outside, from left to right, and number it from large to small.

4) The temperature of the welding paste storage refrigerator is 0℃~10℃. The refrigerator temperature must be recorded every 6 hours, and the “Refrigerator Temperature Record Form” should be filled in.

5) The storage conditions of welding paste are set according to the recommended values of the welding paste supplier.

• Reheating

1) When taking welding paste, based on the first-in-first-out principle (serial number from small to large). When taking it, fill in the time of taking it out from the refrigerator on the control LABEL and fill in the corresponding “Welding Paste Use Control Table”.

2) After filling in the time of taking it out, it needs to be placed in the reheating zone to reheat. According to the amount of production line, ensure the safe amount of welding paste in the reheating zone.

3) Before using welding paste, confirm whether the welding paste in the reheating zone meets the reheating conditions (4H<T<72H).

4) The reheated welding paste should not be at room temperature for 72 hours. It will be scrapped if it exceeds this period.

5) If the reheating welding paste does not exceed 72 hours, it can be put back into the refrigerator for storage.

• Stirring

1) Then stir the welding paste. The automatic stirring time of the mixer is set to 3 minutes. For specific methods, please refer to the “Welding Paste Mixer Operation Specifications” and fill in the collection time on the welding paste control LABEL.

• Use

1) The welding paste must be used up within 24 hours after the can is opened and put on the line. The empty can be recycled. If there is plenty to spare within 24 hours, it must be handed over to the production supervisor for disposal. The opened welding paste cannot be stored in the refrigerator.

2) To ensure that the production line does not stop, when there are 10 bottles of <5kg> of the same type of welding paste left in the refrigerator, the production line leader must go to the warehouse to collect new welding paste.

3) The welding paste is added in small amounts and multiple times. Each time the welding paste is added, it must be kept at about 7~10mm (about half the height of the steel scraper blade).

4) The operator needs to stop the equipment for 20 seconds and wipe the steel plate manually. After cleaning, check whether the tin needs to be added, return the excess welding paste on both sides of the scraper to the printing area, and check the printing quality. There must be no short circuit, less tin, more tin, missing printing, and offset. The printing offset must not exceed one-quarter of the pad.

5) If the machine is stopped for more than 30 minutes, the welding paste should be scraped and stored in the can first.

6) If the welding paste on the edge is found to be agglomerated, it must be cleaned in time and must not be shoveled into the printing area.

7) If welding paste is found on the steel mesh during printing and cannot be scraped clean, the technician must be notified immediately to handle it. It is judged that the printing pressure needs to be increased, and the printing speed needs to be reduced or the scraper is damaged and replaced.

8) The printed PCB must be mounted and reflowed within 4 hours, otherwise it must be cleaned.

9) After the welding paste is opened or added, the welding paste cap must be tightened.

• Scrap

1) The welding paste can be added continuously to ensure the flux activity in the welding paste. The welding paste should be used up within 24 hours after opening the bottle, otherwise it should be scrapped.

2) If it is continuous production and continuous addition, it is calculated based on the opening time of the last bottle of welding paste plus 24 hours.

3) The welding paste shall be scrapped if the temperature returns to normal for more than 72 hours.

Abnormal Situation Handling

1) The welding paste shall be scrapped if not used up within 24 hours after opening the can or if the temperature returns to normal for more than 72 hours.

2) The welding paste solidified around the printing scraper and the steel plate during production shall be scrapped.

3) The welding paste scraped off from the printed PCB shall be scrapped.

4) Pcbandassembly SMT processing: When the refrigerator cannot operate normally due to a power outage or other abnormalities, the electrician should be notified immediately for maintenance. Ice packs can be placed for refrigeration within 24 hours.