White Papers

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Papers by Mike Fenner

• New Developments in High Performance Solder Products for Power Die Assemblies

  by G. Wilson, Mike Fenner, Andy C. Mackie PhD

  The use of special purpose solder pastes in power die attach is well-established offering low voiding and reliable bonding in volume manufacturing. However these materials are designed around high lead alloys and applied by dispensing. IGBT circuits are made by printing high tin alloys to multiple die sites, placing die and reflowing in a process more similar to conventional PCB or hybrid thick film assembly. This paper describes how the opportunity was taken to make use of the latest developments in Pb-free SMT flux technology and re- optimize them to the different requirements of IGBT die attach.

  We rehearse the attributes and requirements of IGBT circuitry and then go on to show how a high performance Pb-Free solder paste has been developed to meet the requirements of large power die attachment (LDA) in IGBT module manufacturing processes. The paste has excellent print and handling characteristics and routinely returns less than 0.5% voiding under large die over a wide range of vacuum reflow conditions. The flux vehicle chemistry offers ease of cleaning to be compatible with the next stage processes of wire bonding & circuit encapsulation.

  Cleaning, wire bonding, void free, die attach, IGBT, solder paste

  [Permanent Link to this Paper]

  Posted on 8 Mar 2010

• Soldering: Is the automotive assembler really different to anyone else?

  by Mike Fenner

  About 40 years ago, automotive manufacturers started to use solid-state devices to replace electro-mechanical voltage regulators. The use of electronics has grown inexorably from those simple two transistor devices. Today, electronics are fundamental to the safe and efficient operation of every vehicle, with over one third of a car’s value represented by electronics. Solders, and the soldering process, are an intrinsic part of any electronics assembly. This article presents an overview of the automotive assembler’s requirements and how these are met. Arising from the transition to Pb-free and the EU RoHS Directive, legislative, safety and environmental compliance issues now exercise a dominant role and must be addressed.

  [Permanent Link to this Paper]

  Posted on 10 Mar 2010

• Wave and Rework in a Pb-Free Environment

  by Geoff Beckwith, Leo Devine, Mike Fenner

  The RoHS upheaval led to a huge investment in research, and even greater output of words describing the best solder paste for reflow and the best alloy for wave. However, curiously little is seen on the most appropriate wave fluxes and less still on flux cored solder wire. This article is meant to fill that void.

  pb-free, Rework

  [Permanent Link to this Paper]

  Posted on 10 Mar 2010

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