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June 2014 • The PCB Magazine 69 SUPPoRTINg THIN STRUCTURES continues in this application than are thermoset resins [1] . After completion of its support function, the support wafer with its bonding layer needs to be removed, either by dissolving the bonding resin, for which process the support wafer needs to be porous to allow for solvent penetration, or by heating and softening the bond layer and sliding off the support structure ("thermal slide process"). Permanent Wafer Bonding These technologies are all temporary bonding techniques for support of a thin wa- fer through demanding processing steps. It should be mentioned that there are quite a few wafer bonding applications that have in common that the bond is intended to be per- manent. There are two types of such perma- nent bonding processes: bonding techniques that make use of an intermediate layer and those that don't use an intermediate layer. Ex- amples of bonding without an intermediate layer are anodic bonding and direct silicon bonding. Examples of bonding with an in- termediate layer are glass frit bonding, solder bonding, and adhesive bonding. These bond- ing techniques find applications in MEMS fabrication. PCB References 1. 3D IC Thin-Wafer Handling Materials Re- quirements, Mark Privett, Chip Scale Review, Nov./Dec. 2012, pg. 24. Karl dietz is president of Karl dietz consulting llc. He offers consulting services and tutorials in the field of circuit board & substrate fabrication technol- ogy. to view past columns or to reach dietz, click here. dietz may also be reached by phone at (001) 919-870-6230. All Flex "Jump Starts" New Products by Real Time with...IPC APEX EXPO 2014 andy shaughnessy speaks with dave Becker, VP of sales at all Flex. topics include all Flex's vast collection of part numbers and their 10-point program for getting new parts to customers, on time. realtimewith.com CliCk To View vIDEO InTERvIEW