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Lecture 16b MEMS Packaging

Lecture 16b MEMS Packaging - Material Costs MEMS Packaging...

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1 October 11, 2001 MEMS Packaging Dr. Bruce K. Gale with assistance from Robert Giasolli Microsystems Principles ENGR 494C and 594C October 11, 2001 Microsystems Principles Material Costs October 11, 2001 Microsystems Principles What Does “Packaging” Mean Connections from chip to outside world Levels of packaging – L0: Features on chip – L1: Chip – L2: Chip carrier – L3: Card – L4: Board – L5: Cables October 11, 2001 Microsystems Principles General Packaging Packaging serves two main functions: Protection of device from working environment Protection of environment from device material and operation Protection from environment Electrical isolation or passivation from electrolytes and moisture Mechanical protection to ensure structural integrity Optical and thermal protection to prevent undesired effects on performance Chemical isolation from harsh chemical environment Protection from device Material selection to eliminate or reduce host response Device operation to avoid toxic products Device sterilization October 11, 2001 Microsystems Principles Basic Package October 11, 2001 Microsystems Principles Packaging One of least explored MEMS components No unique and generally applicable packaging method for MEMS Each device works in a special environment Each device has unique operational specs Electrical protection Electrostatic shielding Moisture penetration (major failure mechanism for biosensors) Interface adhesion Interface stress Corrosion of substrate materials Mechanical protection Rigidity; must be mechanically stable throughout device life Weight, size, and shape for convenience in handling and operation
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2 October 11, 2001 Microsystems Principles Major Issues in MEMS Packaging Literature is scarce Proprietary processes Up to and exceeding 75% of total cost MEMS must often be in direct contact with environment Often package must be designed specifically for device • Reliability Media compatibility • Modularity Small quantities Release and stiction Die handling and dicing • Stress • Outgassing • Testing Encapsulation/ hermetic seals • Integration October 11, 2001 Microsystems Principles Basic Packaging Operations Backside preparation Die separation Die pick Die attach (a) Inspection Wire Bonding (b) Preseal inspection Packaging and Sealing (c) Plating Lead trim Marking Final Tests October 11, 2001 Microsystems Principles Basic Package Types Dual inline package (DIP) Chip Carrier Pin Array October 11, 2001 Microsystems Principles Die Separation • Dies – Batch fabrication and parallel processing – Chop up device October 11, 2001 Microsystems Principles Basic Packaging Methods Wire bonding used to connect microstructures to macro world Uses variety of metals, Au/Al combination popular Flip chips Solder bumps used to attach flipped chip Quick universal connection
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