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Unformatted text preview: testers determine which ICs are good
– Don’t want to package bad chips ($$$) – Label package properly (chip speed = $$$) • Testing MEMS functionality requires released MEMS
– Current testers not compatible with MEMS • What could replace wafer test for MEMS?
– Electrical test structures probed before release? – Test individually (manually) after release? – Test only after packaging? • MUST design with testing in mind!
Microsystems Packaging: An Introduction Page 48 © 2003 Sandia National Laboratories Advanced Design Issues: Wafer Test
• Design for Test
– Is testing even possible? – Internal probe pads for test provided? – Self-test of device once it is packaged? • ADXL150
– Electrical self-test possible – Evidence of probing on “unused” pads, as well as “real” pads
Microsystems Packaging: An Introduction Page 49 © 2003 Sandia National Laboratories Packaging Processes
• • • • Wafer bonding Dicing/Singulation Pick and Place Mechanical Connection to Package/Circuit Board
– Die attach • Electrical Connections/Interface
– Wirebonding – Flip chip bonding • Sensing Connections/Interface
– Connectors – Material types • Environmental Protection
– Sealing – Overcoat deposition Microsystems Packaging: An Introduction
Page 50 © 2003 Sandia National Laboratories Dicing: Separate Wafer into Die
• Wafer sawing standard today
– Diamond saw with coolant – Only used on unreleased wafers • Wafer-to-wafer bonding allows traditional sawing
– Bonded glass, Si cover wafer on released MEMs wafer • Some alternate methods:
– TI patent: partial saw, back grind – Saw wafers, protect MEMS with deposited films – Scribe and cleave – Other proprietary methods
Microsystems Packaging: An Introduction Page 51 © 2003 Sandia National Laboratories Die Separation: ADXL150
• Rough, chipped edges indicate wafer saw • Believed to be post-release, using temporary protection for the MEMS devices • Note that you cannot use edges for precision alignment (spec is ±1° die to package) Microsystems Packaging: An Introduction Page 52 © 2003 Sandia National Laboratories Handling Individual Die Post-release
• Free micromachines
– Sensitive to particles – Damag...
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This note was uploaded on 09/02/2010 for the course MEEN 5050 taught by Professor Himanshuj.sant during the Spring '10 term at University of Utah.
- Spring '10