Using micro-electroforming and micro-assembly technology to fabricate vertical probe card

This paper is characterized by using MEMS process to fabricate and assemble vertical probe cards, and form their top and bottom guides in both vertical and horizontal directions simultaneously. Combining LIGA-like process with a novel CMP-like polishing process enables us to significantly promote the overall co-planarity of probe cards as exactly as within 1 gm. In the assembly procedure, we mainly adopt a kind of SU8 photoresist (PR) notable for being used to coat high aspect ratio micro-structures to assemble plated probes in a row and then take them off by means of inverse electroplating technique. In terms of the design of probe guides, we design them into open comb structures with a view to getting fast assembly. Their materials could be chosen either SU8 or insulating material on metal, which features with the advantages of excellent mechanical characteristics, wear-resistance and better insulation. A space transformer made of advanced flip chip package is then employed to transform signals between printed circuit boards and probe module so that helps us hit the ultimate targets of mass production and low cost. Finally, the proposed vertical probe cards are also convenient to assemble, maintain and dismantle. Only by taking the signal converter atop on the probe cards off can we arbitrarily replace any damaged single probe with a new one when we need to change probes.