Entwicklung und Optimierung von HF-Mikrofederkontaktelementen zur temporären Kontaktierung von Mikrosystemkomponenten

• Development and Optimization of high-frequency contactelements for temporary assembly of microsystem components

Spanier, Gerd; Mokwa, Wilfried (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2007)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2007

Abstract

This publication describes the development, production and characterization of microspring contact elements for temporary and permanent assembly of microsystem components. Those elements provide a microsystem with the possibily of testing each single component prior to permanent assembly. After providing each contact of the single components with a studbump the component is fip-chiped on top of the microsprings. The electrical contact is then achieved by applying a sufficient contact force. Mechanical tolerances can be equalized by the microsprings. If required, the temporary contacts can be converted to permanent contacts by a reflow process or by applying an adhesive. The challenge of this work is to demonstrate the ability of the contact elements to be used at a frequency range up to several GHz. To meet the requirements of modern semiconductor devices the contact elements were miniaturized as much as possible. To perform the characterization an optimal test platform was developed on the basis of companar waveguides (CPW). Additional optimization strategies were presented. To achieve an optimal design the microsprings were simulated mechanically (ANSYS) and electrically (Ansoft HFSS). The mechanical simulations were performed to achieve a sufficient contact force without plstical deformation of the construction. To maximize the high frequency range electrial simulations were performed. As a result of the simulations the microsprings were designed spiral symmetric with three cantilevers. The outer diameter was set to 250 µm. The 3D-microsprings were produced by using LIGA-processes. The possible aspect-ratios (height:width) of the processes, in particular of the lithographic processes have been the limits of the construction. The mechanical characterization of the microsprings was performed by the use of a needle prober. To characterize the electrical performance, scattering parameters and TDR/TDT-measurements have been performed. A usability of the contact elements for frequencies up to 8.5 GHz could be demonstrated. The influence of the contact elements itself could be neglected in comparison to the influence of the overall design and tolerances.

Institutions

• Chair of Materials in Electrical Engineering I and Institute of Materials in Electrical Engineering [611510]