Ultra Long Needle Geometry Probe Card Development for Wafer Level Test

Wafer level testing within MEMS DLP (Digital Light Processing) device is a key issue for the expected growth of the MEMS market. MEMS devices´ wafer sorting is hard due to a series of difficult factors, including the height of the glass, device pitch and complicated processes. Therefore, the general needle card can´t be used to probing for these devices. In this paper, we develop a new ultra long tip needle´s geometry for DLP device testing. This paper conducts experimental and numerical investigation into the probing technique to test the functionality of DLP devices. A single needle three-dimensional computational probing simulation model was developed to find out the suitable design parameters of ultra long tip needle, analyzing the effects of the needle geometry on the scrub mark profile, the stress distribution during wafer probing and compare with general cantilever needle card. The experimental and numerical methods presented here can be used as useful performance evaluation tools to support the choice of suitable ultra long tip probe geometry and wafer testing parameters.