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Intermetallic Issues With Wire Joining by Thermocompression & Soldering Dr Henning Leidecker Goddard Space Flight Center, Code 562 Parts, Packaging, and.

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Presentation on theme: "Intermetallic Issues With Wire Joining by Thermocompression & Soldering Dr Henning Leidecker Goddard Space Flight Center, Code 562 Parts, Packaging, and."— Presentation transcript:

1 Intermetallic Issues With Wire Joining by Thermocompression & Soldering Dr Henning Leidecker Goddard Space Flight Center, Code 562 Parts, Packaging, and Assembly Technologies Office Oct 2003

2 Outline Wire Bonding Au-Al Intermetallics – Equil. Intermetallics – Rates Degradation/Failure GFSC Websites Wire Soldering Au-I Intermetallics – Equil. Intermetallics – Rates Degradation/Failure GSFC Websites

3 But first, a bit about COTS... The Commercial Off-The-Shelf (COTS) market is huge and competitive: the stakes are high. Hence, some of the best designers in the world develop COTS parts, sharply focused on a target market. Often, they hit this market with exquisite precision. But trade-offs are usually made in this target-focused design, and the resulting parts may not be apt for a different market whose needs differ from the target. Reliability over long times (5+ years) is a prime example. ==> DO NOT FEAR COTS BUT BE WARY <==

4 Gold-Indium Phase Diagram

5 Optical Cross-section of a ball bond

6 SEM – intermetallic at base of bond

7 SEM – cross section

8 Note Cracks

9 Familiar Intermetallic?

10 Carbon Exuding From Grain Boundaries

11 Intermetallic Remaining

12 Normal and Carbon-Sensitive Images

13 GSFC Websites about this topic NASA/GSFC Wire Bond Website: Selected Topics of Interest to GSFC Parts Richard Katz Website: Pay special attention to Horsting's work on the effects of impurities on the bonding pad; see also Issues with Gold Electroplating for Microelectromechanical Systems Applications, by C. A. Kondoleon, et al. Materials Research Society Symposium Proceedings 2002, 687 ( )

14 Indium Solder and 1 mil Gold Wires Before there was wire bonding (e.g., thermocompression), there was soldering Pb-Sn solder dissolves gold; not good for 1 mil. About early 1950's, Indium was used to solder thin gold wires --- Initial success, followed by high frequency (--> 100%) of the joins breaking. The short-term attractiveness of Indium as a solder induces repeated lessons learned!

15 Wedge Bond of 1 mil Au to In

16

17 Au changing into Au-In compound

18 Au wire with In attack: side view

19 Au wire with In attack: top view

20 Indium Solder and 1 mil Gold Wires

21 GSFC Websites about this topic NASA/GSFC Technology Validation Assurance Web Site: Reliability of Laser Diodes for Space Flight Applications: m


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