After the SMT pick and place chip machine processing ,many factories will encounter the phenomenon of bending and rocking of the circuit board during reflow soldering. In severe cases, it may cause bad SMT phenomena such as empty welding of electronic components and tombstones. These phenomena are caused by Because of what? It is because of the uneven pressure on the board or the uneven pressure on the board, which leads to the phenomenon of bending or rocking. When the board passes through the high temperature of reflow soldering, the circuit board will become soft, and the thermal expansion and contraction of the circuit board material. The characteristics of chemical factors have resulted in bent plates and rocker plates.