A Case Study of Delamination Failure Analysis of PTFE Substrate for High Frequency and High Speed PCB

With the development of electronic communication technology, polytetrafluoroethylene (PTFE) material is widely used in the manufacture of high frequency and high speed printed circuit boards. For ordinary printed boards, delamination and blistering are common problems in its use, and there are many studies in the industry, but there are few studies and introductions on the delamination failure of PTFE substrates. In this paper, the reason of delamination of a double-layer PTFE substrate is analyzed by SEM&EDS, metallographic cross section and thermal stress test. It is found that the delamination may be related to the immersion of organic solvents (alcohol, isopropanol, acetone, etc.). Further, the PTFE substrate is immersed in different organic solvents for thermal stress test, and the results reproduce the delamination failure phenomenon. The mechanism of delamination is studied by fluorescence permeation technique, it was found that organic solvents could invade the gap between filler/glass fiber and PTFE, resulting in delamination of PTFE substrate.