Function of hot air pad

Hot air pad （Thermal Relief）, Also called cruciform pad , The design of flower pad is only to solve the problem of in-line devices and VDD perhaps GND When there is a connection , Designed to reduce the heat dissipation area .
In detail, there are 2 A role ：
1. Prevent heat dissipation ： Due to the power supply on the circuit board VDD And ground GND It is provided by large pieces of copper foil , Copper foil has very good thermal conductivity , During welding , If a large piece of copper foil is directly connected through the hole , Then the heat dissipation will be very fast , The temperature of the welding point cannot meet the requirements , Prone to false soldering （ This is the so-called influence process ）, Therefore, in order to prevent false soldering caused by too fast heat dissipation , The through hole of the power supply and the ground is connected by the cross pattern process , Reduced contact area , Reduce the heat dissipation speed , Easy to weld .
2. Prevent large pieces of copper foil from squeezing the via and hole wall due to thermal expansion and cold contraction , Cause hole wall deformation .