Highly Thermally Conductive Z-axis Adhesive Film
btechcorp uses millions of graphite fibers per square inch aligned through the thickness of a thermoplastic adhesive to produce a Thermal Interface Material with very low thermal resistance….HM-2.
We just completed the first phase of our program to further reduce the HM-2 resistance by 25% for the thicker bondlines needed for larger bond areas. The original HM-2 resistance of 0.07 C-cm2/W at 100 microns thick is now down to 0.05 C-cm2/W and this modified HM-2 is currently in production.
HM-2’s low modulus thermoplastic provides excellent stress absorption… ceramic/Al coupons (10 cm2) had no degradation after thousands of thermal cycles. Customer thermal cycling in the -40C to +150C range is now underway using 25 cm2 coupons for an automotive application.
The second phase of our resistance reduction effort is underway. It is focused on adding an interposer layer to the graphite fiber ends to reduce the phonon scattering at their interface with metallic substrates.
Other polymers can also be used with the graphite fibers to meet a variety of application requirements.
Microelectronics Reliability 52 (2012) 2443-2446, Yasushi Yamada
A power semiconductor module using a bonding film with anisotropic thermal conduction has been studied.
The bonding film consists of polyamide with a low Young’s modulus and Z-axis-oriented fine graphite
fibers. All the materials of this device, including the insulated substrate and base plate, have low
coefficients of thermal expansion. The bonding film is inserted between the baseplate and an aluminum
active heatsink. No significant changes in the thermal resistance or cross-sectional microscopy images
were found after thermal cycling tests.
HM-2 TIM thermal cycling
Ultra Fine Pitch Thermoplastic Anisotropic Conductive Adhesive (ACF) Adhesive for Bumpless Flip Chip Packaging and Advanced Displays
btechcorp introduces the TP series of Z-axis electrically and thermally conductive thermoplastic film adhesives. Containing almost 1 million Z-axis nickel fibers per cm2, TP films are as electrically conductive as solder and have a lower total thermal resistance than silver filled adhesives.
TP films use 8 micron diameter nickel fibers with 3 micron spacing between fibers. Very high X-Y electrical insulation on the outer surface of each fiber means that TP can be used for circuits with as little as 8 micron spacing between pads.
Due to the repeatable hot melt capability of thermoplastics, TP films allow staged assembly. For example, TP can be laminated to a bumpless wafer and after dicing the die can then be bonded to packaging substrates.
Since TP strongly bonds to all metal substrates, it has excellent lap shear and peel strength properties. With a much lower modulus (< 0.10 GPa) than epoxies, TP offers outstanding CTE mismatch stress absorption.
The TP series uses three different thermoplastic resins to offer application flexibility in bonding temperature and thermal cycling capability. Bonding temperature options are 125C, 150Cand 185C. Thermal cycling capability ranges from -50C to +90C, +130C and +160CC.
btechcorp also offers custom thermoplastic resin versions of this TP product family to meet unique application requirements.