6.4 Maintenance frequency and maintenance label

6.4.1 In general, each welding and maintenance will heat the PCBA plate twice (once for dismantling and welding respectively), so the maximum number of rework and maintenance for each bit number of PCBA plate is two times (if the product has special maintenance times, it shall be carried out according to the product requirements), refer to the following table:

PCB board heating times statistics table

6.4.2 Repairing repair/spot welding with electric soldering iron (without replacing components) is not regarded as a maintenance, such as: tin-filling for components with less tin, and tin-spot welding with fake welding. The use of a heat gun for tin-repair/spot welding is considered as a repair, even if the component is not replaced.

6.4.3 Maintenance mark: Each new maintenance worker shall be given a numerical code before starting to repair the board. After each repair, the corresponding maintenance mark shall be pasted at the specified position: Add "W" in front of the digital code when fixing the bad appearance, "X" in front of the digital code when fixing the bad function board of the download line, "P" in front of the digital code when repairing the bad function board of the PCBA group, and "R" in front of the digital code when reworking in batches.

After mainboard maintenance, use the printed maintenance label and paste it in the corresponding position given by IE. After repairing the small board, mark the edge of the board number with black or blue oil marker as maintenance mark. QC visual inspection and test good board can only use oil marker on the maintenance label sticker marking, can not use red color oil marker.

6.5 PCBA and material baking

6.5.1 If PCBA has been exposed in the workshop for more than 168 hours (since SMT has been installed in the furnace) and CSP/BGA/LGA larger than 6mm, LGA with bottom cooling surface and POP need to be repaired, the PCBA should be baked before the maintenance operation.

6.5.2 Setting of baking temperature and time: the main board of the mobile phone is baked at 80°C for 24 hours; The mobile phone tablet is.

6.5.3 After the materials are brought back, they should be put into the drying box at the first time. When the materials are released, the principle of first-in, first-out is followed, and the time of opening the drying box should not exceed 30 seconds.

6.5.4 Baking record: When the PCBA in the maintenance area needs to be baked, the model, quantity and starting time of baking shall be recorded in the report in detail.

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