RF Packaging Jason Shin Fall 2007: ECEN 5004 Fundamentals of Microsystems Packaging Graduate Presentation

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

Introduction: Past RF Technology Technology focused on:  Analog communication  Short Distance Radar  < 100 [GHz]

Introduction: Present RF Technology RF technology today is integrated in most electronics spanning all engineering fields. Quazioptical frequencies used

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

Devices – Passives Problems with normal passives  Inductors  Capacitors  Solutions (packaging)‏ Passive uses  Matching  Filters  DC/RF choke/block  High Q Cavities (Low ESR)

Devices – Actives Transistors  High Power  Low Power  Various Packages Oscillators Bolometer/Diodes  Mixing  Power Measurement  Rectify RF power

Devices – Active Fabrication RF Transistors vs. typical CMOS transistors  Gain Product Bandwidth  Lower Capacitances Exotic Processes very small tolerances Different Materials/Structures  LDMOS

Devices – Active Packaging Parasitic Impedances limit performance Technologies Used  Plastic Package  Wire Bond  Flip-chip

Devices – Packaging Interface RF Transistor Example

Devices – Packaging Interface

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

Substrates - Introduction What are we looking for?  Interconnects Connecting DC Biasing Interconnects between Devices (RF and DC)‏  Microstrip Antennas  Matching 50 Ohm Impedance Transforms  Materials Flex, Brittle, Flame Retardant, etc.

Substrates – Materials Polytetrafluoroethylene (PTFE)‏  DuPont brand name Teflon Ceramic Woven Glass Thermoset Plastic

Substrates – Materials Criteria commonly used in selecting a material:  Military: Materials meet or are tested in accordance to military specifications.  Commercial: materials are designed for cost sensitive applications (military grade materials can be used in commercial applications but pricing is higher).  Multilayer: mechanical properties are such that allow for reliable multilayer (MLB, other than basic stripline) constructions  Hybrid: mechanical properties are such that allow for reliable FR4 hybrid MLB constructions  Broad Band: dielectric constant allows for very high frequency and/or high broadband use  Temp Cycling: electrical and mechanical properties allow for stable use in temperature varying environments  Surface Mount: mechanical properties allow for surface mount technology  Miniaturize dielectric constant reduces sizes of circuit elements

Substrates Conductors can be:  Rolled  Electro-deposited Various characteristics can be designed for Tradeoffs mostly apparent in cost Many different RF software packages used to model on substrates

Substrates – Flex Substrates

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

Fabrication - Introduction All techniques described in semester apply Active Antenna Laboratory  Milling  Chemical Etching

Fabrication - Milling Two Machines Smallest tool 5 mil

Fabrication – Chemical Etching Process  Design on computer  Print on Blue Paper  Iron/Press on Substrate  Peal  Pour Acid

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

μCoax Hybrid Coupler 4x4 Butler Matrix Patch Antenna

μCoax

RF Packaging Introduction Devices Substrates Fabrication Miscellaneous RF Packaging Conclusion

RF usable frequencies continue to increase Passive and active devices must control unwanted parasitic effects in order to scale  Change in size/package  Change in process Substrates and fabrication techniques continue to become less expensive and more robust Interesting progress can be made with these advancements