Microwave Packaging Technology

3 DAYS

Microwave Hybrids, MICs, RF MMIC modules all require a unique set of materials and processes necessary to achieve reliable operations in extreme military and commercial environments. This three-day course examines all aspects of microwave packaging from a practical perspective. The instructor shares valuable lessons learned from years of experience. Design issues, material trade offs, process selection are all covered in detail with the goal of imparting useful information to the students so they can return to the workplace better equipped to assemble and manufacture reliable microwave hybrids for military, space, and other high reliability commercial and medical device applications.

This course is intended as an introductory to intermediate level course for process engineers, designers, quality engineers, and managers responsible for design and manufacture of microwave hybrids.

Course Outline

Day 1

Introduction to Microwave Technology
Terminology and product definitions
Microwave hybrids, RF/MMIC modules
Military, space, commercial and medical products

Military Requirements Flow Down and Design Guidelines
MIL-PRF-38534 Hybrid Performance Specification
MIL-STD-883 Test Methods

Manufacturing Assembly Process Overview
Basic hybrid microwave manufacturing process flows
Clean room requirements and industry protocols

Design for Manufacturability (DFM)
Rationale and significance of DFM
Typical problems encountered during hybrid manufacturing and how they can be prevented!

Wafer Fabrication Processes
GaAs (Gallium Arsenide) wafer fabrication
GaN (Gallium Nitride) on SIC wafer fab technology
Device feature identification and significance
Review of wafer fabrication defects at incoming inspection
e.g., airbridge and channel damage, excessive probe marks

Packaging Design Considerations
Thermal analysis, simulated stack up and junction temp calculations
Stress analysis and basic material consideration and trade offs

Day 2

Substrate Technology
Teflon PTFE (duroid) and other soft board material sets
Alumina ceramic substrate fabrication

Thin Film Processes on Ceramic
Sputtering vs. vapor deposition
Photolithography, coat, and etch
Performance issues
Plating processes and specifications

Laser Trimming of Precision Thin Film Resistors

Material and Process Fundamentals for Component Attach
Silver epoxy attach of substrate and MMIC die
Handling and assembly of bare die
Solder and epoxy attach of discrete components

Eutectic Soldering Processes
AuSn solder attach of GaAs chips
Other eutectic solder process
Issues with die voiding and how to detect

Die, Substrate, and Package Compatibility
Coefficient of Thermal Expansion (CTE)
Material selection and design trade offs

Thermal Impedance and Importance of Minimizing Junction Temperature
Simple excel spreadsheet demonstrates importance of proper material selection for typical microwave hybrid material sets

Review of Defects from the Component Attach Processes

Overview of Common Cleaning Processes and Potential Problems
Wet chemicals, oxygen/argon plasma, UV Ozone

Day 3

Wirebonding and Interconnect Process Overview
Ultrasonic/thermosonic bonding
Thermocompression bonding
Ribbon bonding
Gap welding
Deep access bonding
Fine wire (.7 mil) bonding gate pads on FETs

Factors that Affect Yield and Reliability
Lessons learned
Review of defects from the wirebond process

Wirebond Design and Layout Guidelines to Facilitate Ease of Manufacture

Hermetic Packaging Process Overview
Seam sealing, laser welding aluminum alloys, solder sealing
Soldering in RF Feedthrus

Hermeticity Testing
Traditional gross and fine helium leak testing per MIL-STD-883 TM 1014
Hermeticity testing options; Optical Leak vs. CHLD vs. Kr -85 Radiflow
Impact of a tighter hermeticity specification

Near Hermetic Packaging Options
LCP and other packaging approaches

Course Summary

Student Examination Test and Review

Student Feedback and Course Critique

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