Here is the abstract you requested from the dpc_2018 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|The application of immersion Tin for QFN production.|
|Keywords: QFNs - Quad Flat No-lead, Immersion Tin, Reliability|
|The Quad Flat No leadframes Packages or QFNs are a type of IC that employs SMT technology rather than solder ball technology for attachment. The primary plating technology is electrolytic tin with the bridging assured by lead frames. However once the dies are singulated, an exposed copper contact remains that is the solderable contact to the carrier panel. Historically, the resultant 2D solder contact between the die and the panel area was accepted as sufficient by necessity. Increasingly immersion tin (i-Sn) is providing the ability to coat the flanks and therefore enabling a 3D connection. The resultant 3D solder joint is referred to as a solder fillet and offers more robust solder joints when compared to the 2D equivalents. Additionally the solder fillets are aesthetically superior to such an extent where Automated Optical Inspection (AOI) becomes applicable. The application of immersion tin is not only practical but is production proven and can cope with both stamping and sawing singulation methods. This workable technology may help to further automate production whilst simultaneously maximizing yields. This paper will discuss the benefits of using immersion tin for QFN production and will include processing techniques and the performance with regard to the established copper alloys that are in existence.|
|Rick Nichols, Product Manager - Selective Finishing
Atotech Deutschland GmbH