Why don't you connect all the pins when welding, and the pins of the components are immersed in tin liquid? Why not connect all the pins together, but print according to?

1 means that the circuit board has solder resist paint, and the solder is limited to local places such as tin-plated pads and component pins.

2. The higher the solder temperature, the smaller the surface expansion force of solder, or the smaller the viscosity of "tin liquid" in immersion welding, so that "tin liquid" is not easy to stick to the next pin.

Therefore, the denser the pins, the higher the temperature of "tin liquid", but it is not necessary to use immersion welding for the welding of pins with small spacing such as chips.

Instead, other bonding methods are used for welding.