PCB Circuit board welding procedure specification

1 Preparation before welding
1.1Material: pay attention to the polarity of welding components,Whether there is the oxidation or not oil in the components foot.
1.2 Tool:Quantity should be consistent with the bom list.It’s 2 particles at most for each time to be taken.We should put the material back to the original palce.
1.3 pcb board:Check board circuit, whether there is short circuit, open circuit, etc on the board..
1.4 The list:Please make sure that the list is correct.
1.5 Workbench:Must make sure that it is neat and clean.If there is anti-static requirements, then we should pay attention to the use of anti-static workers appliances.At the same time the operator should wear anti-static wrist str
2 Implement welding
2.1 Safe use and scientific use of iron,Keep the tip clean.Iron head working temperature: lead welding temperature at 350 ~ C, lead-free welding general at a temperature of 380 DEG C, turn off the power when not in use.
2.2No pressure should be applied during welding.General solder joints takes about 2 ~ 3 seconds 
to complete it. Notice:should not be taken before the tin solder was complete freezing. In order 
to avoid insufficient solder we should correctly use flux. 
2.3Correct posture of welding operation.Normally,distance from Iron to nose should be not less 
than 20cm, Usually 30cm is suitable .
2.4Discrimination of polarity of welding components.The welding components should be neat, 
middle, paste board.The welding sequence of the device shall be based on the principle that the 
first welded element does not affect the welding of the following elements.First, we weld small 
capacitance and other devices,and then weld the larger elements,lastly we weld plug.
2.5we should use the tools properly, and put them away after using them.
2.6Treatment of waste after welding.we should Clean up the waste and throw it in the trash.
2.7Try to avoid repeated welding
2.8Sealing-off the components.
1)Proper use of tools,depends on the welding element set (iron, hot air guns, tweezers, etc.).
2)The correct use of tin gun
3)Temperature and time should be reasonable.
3 Treatment after welding
3.1Pay attention to the following points after welding:
1)Check leak welding, welding fault (polarity welding anti), short circuit phenomenon, weld etc.
2)Check solder joints for proper solder,Whether there is good gloss and even on the surface .There should be no burrs, gaps and cracks on the surface.Solder surface should be clean.
3.2To properly use the wash plate water:Clean the residue on the PCB board, such as tin dross, tin scrap, component feet, etc. The user should do a good job protection measures.Because Plate washing water is volatile and flammable,the leftover should be installed in place.Don't waste water.
3.3Power on detection .
1)Measure the input terminal of the power supply with Multimeter resistance block,to see if there is a short circuit.If yes ,we should be excluded before power up.
2)According to the schematic diagram of the circuit module circuit inspection,If you have any questions, you can ask the Engineer
3)After the completion of the power must be assembled according to the list of IC, check the error
3.4PCBA should be checked with a good electrostatic bag packaging, can not be placed at random.