Changes of the coplanarity of SMT-components during soldering and their Measurement

The coplanarity between the substrate (or printed board) and the SMD-package is a very important characteristic. This coplanarity depends on the warpage of the board and the package. An insufficient coplanarity can lead to open solder joints and/or bridges of the solder joints. Additional mechanical stress (especially in z-direction) inside of the solder joints may also occur. The warpages of the packages and the boards change during a soldering process. The Thermoire®-Measurement gives the possibility to control the warpage under soldering conditions. The IPC-Bow and the IPC -Twist are characteristics, to evaluate the warpage of printed boards.