Warpage control of wireless LAN SiP during manufacturing process

In this study, the warpage of WLAN strip after reflow process, which contains 7times5 WLAN modules, is considered. 3D thermo-mechanical FEM simulation is carried out to find out the warpage distribution and maximum warpage after reflow process. Experimental investigation on the warpage measurement of the package is also performed to verify the simulation results. Furthermore, some new designs on the manufacturing of the module strip, such as reducing the density of module or cutting grooves on the PCB, adding extra pins on the carrier, are proposed and compared with the currently used one. The results show that pin carrier is an effective way to reduce the warpage. The more pins on the carrier, the more efficient in reducing the warpage. Decreasing the unit density on the PCB or cutting grooves in the PCB are also ways to reduce the warpage. The less units on a single PCB sheet, the smaller the warpage. The most effective method to reduce strip warpage is to add a central pin on the PCB which can help control the maximum warpage to be within 50 mum.