Richard Koba, Materion

Join Richard Koba of Materion at the LED A.R.T. Symposium


Abstract: Bonding a Ceramic XLamp ® to an Al Heatsink with a Very Thin Bondline Using BondFlow ™

BondFlow™ is a new die attach (TIM1) material that can be spin coated onto the backside of a wafer, B-staged, diced and then cured at 250 ℃ within 2 seconds. Previous research has demonstrated that BondFlow has excellent adhesion to bare ceramic and aluminum. It also has an unusually thin bondline, e.g, between 3 and 20 μm. For this investigation, BondFlow is evaluated as a TIM2 adhesive between the backside of a ceramic LED submount and a bare aluminum heatsink. The good thermal conductivity of silver-filled BondFlow, coupled with its unusually thin bondline, should produce a thermal impedance lower than that of typical TIM2 greases and pads. Typical TIM2 thermal pads have a thickness of 500 μm.

BondFlow was deposited onto the backside of CREE ceramic XLamp® LED submounts and then B-staged. Since it is not practical to heat an entire aluminum heatsink to 250℃, a Finetech Sigma™ die attach system was used to apply a lower temperature to the heatsink, but pulse the XLamp ceramic to 250℃ after pressing onto the heatsink. A custom collet adaptor was built to apply a load onto the ceramic surrounding the central LED array/ phosphor circle. Bondline thickness and curing conditions were optimized into order for form a bond with minimal voiding. The XLamp bonded Al heatsink was then subjected to simulation of SAC solder attach (230℃ for 5 minutes). The XLamp bonded Al heatsink was also subjected to temperature cycling.

BondFlow can be used as a low impedance TIM2 material between a ceramic XLamp and an aluminum heatsink. By modifying the heated collet of a Finetech Sigma™ machine, thermocompression bonding of the ceramic onto aluminum at 250℃ can be achieved quickly.


About Richard Koba:

Richard Koba is Senior Marketing Manager in the Advanced Materials Business Unit of Materion Corporation. He is a product manager for ceramic RF packages and cover products, including the Materion product lines of solder ribbon and preforms, CuPacks™, CA-Packs™, Epo-Lids™and Combo-Lids™. He joined Zentrix (now Materion) in 2007, and has worked in the packaging/thermal management industry since 1994. .