Girish Deshpande

Thermal management coatings via combustion chemical vapor deposition (CCVD)

Thermal management, especially for power systems, is a major issue for electronic packaging. It requires electrically insulating and thermally conductive materials with high breakdown strength and thermal conductivity. Conventional insulator materials for circuits such as epoxy, FR5, and gas, are poor thermal conductors. The alternatives, aluminum nitride, synthetic diamond and beryllia, are expensive, limited in size, and difficult to process. MCT, in conjunction with the U.S. Office of Naval Research and the University of Arkansas, is modifying its patented CCVD process to create an electrically insulating coating with relatively high thermal conductivity and breakdown voltage directly on to the base plate with no post deposition processing. The power and control circuit interconnects and components are to be applied directly onto the insulating layer. The preliminary results, measured on one-inch square coupons, are promising. The ceramic/polymer composite has excellent adhesion to polished Al-SiC substrate (>25 MPa), a breakdown voltage of higher than 1000 V, a leakage current less than 20 nA at 1000 V bias, and a substrate/coating thermal conductivity of 110 W/m K.

Planar low k dielectrics applied using a modification of combustion chemical vapor deposition

As electronic circuitry continues to shrink, the need for smaller, denser components is rising. But when components reduce in size, there is a greater opportunity for the circuits to short circuit and create cross talk. Better methods of incorporating insulation are needed. MicroCoating Technologies (MCT) is developing a new thin film technology to enable the reduction in the space between conducting pathways in integrated circuits and printed wiring boards. This process adapts the Combustion Chemical Vapor Deposition (CCVD) process for producing planar polymeric films. This modified process can potentially reduce the number of steps in the traditional spin-on process from four (deposit, spin, cure, and planarize) to one, offering significant cost savings and greater versatility. Commercially available materials used in industry including copper clad boards and HD-Microsystems Pyralin/sup TM/, PI-2611, a difficult to planarize polyimide, were used extensively in this study. Coatings were made that were highly adherent and pinhole free. The degree of cure was between 40% and 70%. Resulting in dielectric constants between 3.75 and 6.75. Through characterization of the coatings, it was revealed that the process could control the dielectric constant, which is strongly affected by the degree of cure, and the degree of planarization simultaneously. Plans for further improvements in the dielectric constant and the degree of planarization have been theorized. The potential to coat patternized circuits with a low dielectric constant polymer with a degree of planarization similar to previous results using spin on processing was demonstrated.