Welding is an indispensable link in SMT chip processing. If there is a mistake in this link, it will directly affect the unqualified or even invalid circuit board of SMT chip processing. Therefore, it is necessary to grasp the correct welding method when welding. Shanghai SMT processing should understand the relevant precautions to avoid problems. Before the chip processing and welding, the solder pad is coated with flux and treated with a soldering iron once to avoid poor tin plating or oxidation of the pad, resulting in poor soldering. The chip generally does not need to be treated. Use tweezers to carefully put the PQFP chip on the PCB board, taking care not to damage the pins. Align it with the pad, and ensure that the chip is placed in the correct direction. Adjust the temperature of the soldering iron to more than 300 ℃, dip a small amount of solder on the tip of the soldering iron, and press down the aligned chip with something. Shanghai SMT chip is processed by adding a small amount of flux to the two diagonally oriented pins, and still holding down the chip, soldering the two diagonal pins, so that the chip is fixed and can not be moved. Check the orientation of the chip again after welding the diagonal. If necessary, adjust or remove and re align the orientation on the PCB board.

When starting to weld all the pins, solder the tip of the soldering iron and coat all the pins with flux to keep the pins wet. Shanghai OEM used a soldering iron tip to touch the end of each pin of the chip until it saw the solder flowing into the pin. When welding, it is necessary to adhere to the soldering iron tip and the soldered pin in parallel to prevent overlap due to excessive soldering tin. After soldering all pins, wet all pins with flux to clean solder. PCBA foundry removes excess solder where necessary to eliminate any short circuit and overlap. Finally, use tweezers to check whether there is false soldering. After checking, remove the flux from the circuit board, dip the bristle brush with alcohol and scrub carefully along the pin direction until the flux disappears.

SMR components are relatively simple to solder. Shanghai PCBA process can first spot tin on a solder joint, then put one end of the component, clamp the component with tweezers, and then check whether it is placed correctly; if it is, solder the other end. It needs a lot of practice to grasp welding skills