Contact Force Experiments and Deformation Analyses of a Cobra Needle Used in Vertical Wafer Probe Card

垂直式晶圓探針卡之探針接觸力實驗與變形分析

邱進東(Jinn-Tong Chiu) ； 張達元(Dar-Yuan Chang)

《中國機械工程學刊》 42卷5期 (2021/10) Pp. 501-507

摘要

Wafer testing requires a probe card with a mass of microprobes as a contact medium between the prober and the wafer. Electric characteristics of the examined welding pads are tested by direct contacts between the microprobes and pads. These needles are subject to deflection or buckling resulting from the contact test, and might lose their original strength. To understand the loading state and deformation process of the needle, this study develops a microprobe testing platform for analyzing a vertical cobra needle. Testing parameters which affect the contact force were investigated, such as the probing overdrive, approaching speed, and probing time. Needle deformation during probing was observed by a computer vision system and evaluated by image processing methods. Furthermore, the finite element model of a palladium alloy cobra needle was established to simulate its contact behaviors in wafer probing for obtaining a wafer probe card with correct test and robust performance.

關鍵字

Wafer testing ； Vertical wafer probe card ； Contact force ； Image processing ； Finite element analysis

並列摘要

晶圓測試需要藉探針卡上的大量微探針做為接觸介質，透過微探針和晶圓焊墊間的直接接觸，檢驗受測焊墊的電子特性。這些探針會因接觸測試所發生的撓曲或屈曲現象，而失去其原始強度。為了了解針的加載狀態和變形過程，本研究開發了適用於分析垂直式Cobra探針的微探針測試平台，分析影響探針接觸力的測試參，包括：針測行程、針測速度、以及測試時間。針測過程中的探針變形由電腦視覺系統觀察並配合數位影像處理方法進行評估。此外，本文建立了鈀合金Cobra探針的有限元素模型，模擬微探針於晶圓針測行程中的接觸行為，以獲得具有正確測試功能與穩健性的晶圓探針卡。