Why is CTE (Coefficient of Thermal Expansion) critical?
There are several reasons why CTE is important. A material with a higher CTE (>100 ppm/°C) will have worse dimensional stability during the circuit fabrication process. Another issue is the reliability of the plated through hole. A high CTE will cause the material to expand more during soldering or other high temperature exposures and can fracture the plated through hole barrel. A material with high CTE could also have a shearing effect on components that have been soldered in place and then the board goes through some thermal cycling.
