Alpha®, the world leader in the production of electronic soldering materials, recently presented a technical paper at the 2012 IMAPS International Conference on Device Packaging held Scottsdale, Arizona.  Rahul Raut, Global R&D Project Manager, presented the methodology to compare the relative performance of different solder materials with varying thermo-mechanical properties and additionally compare the impact of CTE mismatch, temperature swings on transient thermal properties, and relative reliability of the solder materials for chip-on-board LED applications.

“Alpha’s specialty materials technologies are based on our strong commitment to R&D and a clear understanding of the need to provide value for our customers in each key step in the LED manufacturing process,” said Ravi Bhatkal, Alpha’s VP – Energy Technologies. “Our well-known soldering materials expertise provides us with a deep insight into the challenging variety of bonding events required to assemble LEDs.”

LED chip-on-board applications typically involve assembling an LED die stack directly on to a high thermal conductivity substrate such as a Metal Core PCB. If solder is used for die-substrate attach for such chip-on-board applications, the CTE mismatch between the die stack and the MCPCB and its impact on thermal cycle-induced (creep) fatigue of the solder material needs to be considered.  Alpha understands that combining thermal shock / thermal cycling, thermal diffusivity measurements, and image analysis of the joint degradation can provide an analytical framework to compare thermal cycling fatigue resistance and hence reliability of various material stacks (LED die-solder-substrate), on an “apples-to-apples” basis.  This allows for selection of the appropriate die attach material for the stack-up under consideration, as well as selection of bond line thickness for the reliability level required

About Alpha
Alpha, a business unit of Cookson Electronics, is the global leader in the development, manufacturing and sales of innovative materials used in the assembly of electronics products. Since its founding in 1872, Cookson Electronics has been committed to developing and manufacturing the highest quality soldering materials. That tradition continues today as Alpha supplies high quality products to the LED, Power Electronics and Photovoltaic industries.  Alpha serves these industries with over 30 locations throughout the Americas, Europe and the Asia/Pacific region.