What are the possible reasons for bad solder joints, and is there any good solution?
(1) Solder balls are formed, and tin cannot spread to the entire pad?
The temperature of the soldering iron is too low, or the tip of the soldering iron is too small; the pad is oxidized.
(2) When the soldering iron is removed, a tin tip is formed?
The soldering iron is not hot enough, the flux is not melted, and the steps work. If the temperature of the soldering iron tip is too high, the flux will evaporate and the soldering time will be too long.
(3) The tin surface is not smooth and wrinkled?
The soldering iron temperature is too high and the soldering time is too long.
(4) Large rosin spreading area?
The tip of the soldering iron is held too flat.
(5) Tin beads?
The tin wire is added directly from the tip of the soldering iron, too much tin is added, the tip of the soldering iron is oxidized, and the soldering iron is beaten.
(6) PCB separation layer?
The temperature of the soldering iron is too high, and the tip of the soldering iron hits the board.
(7) Black rosin?
Temperature is too high.
