In a previous post, we discussed the shortcomings of round bond wires for RF applications from both a performance and reliability standpoint. Today we are taking a step back and discussing wire bonding in general and how to avoid basic pitfalls.
Wire bonding is a popular interconnect technology due to its reliability, versatility and performance. Each year, our industry creates over ten trillion semiconductor interconnects– more than 1000 interconnects for every human on Earth annually. For the last 50 years, the vast majority of these connections were wire or ribbon bonds, so one would assume that the process is highly reliable. Unfortunately, this is far from the case. Wire bonding still suffers failures during processing as well as in the field and sometimes at great cost.
Direct printing of semiconductor interconnects with finely-sprayed inks containing conductive nano-particles is a promising alternative to wire bonding. The US Department of Defense lists eight common failure modes for wire bond failures. Six of the eight failure modes listed by the DoD are exacerbated by the wire-bonder’s injection of contact energy– either thermal or mechanical– into the bond pads of the die or the substrate.
The Aerosol Jet process is a non-contact printing technology that has proven to be a more gentle method of producing interconnects, which is of particular interest for those packaging fragile parts such as GaAs. Furthermore, the Aerosol Jet process is not limited to planar arrangements. ICs can be stacked or arranged on curved surfaces to save space or improve signal integrity.
We recently wrote about this in great detail in Chip Scale Review. Our article, titled: Avoiding the Downfalls of Bond Wires with Printed Interconnects – covers this in more detail. In it, we talk about the greatest wire bond failure in history as well as the main reasons wire bonds fail and the capabilities needed to reduce wire bond failures.
Wire bonds will not be fully replaced by printed interconnects any time soon – however more and more production customers are looking to printed solutions for increased quality and performance.