Archives for March, 2010

Ultra-Low Silicone Thermal Gap Filler Provides High Thermal Conductivity and Conformability

MH&W International has added new TP-S3LS ultra-low silicone gap fillers to its line of thermal interface materials. TP-S3LS pads contain less than 50 parts per million of silicone while providing 3.0 W/mK of themal conductivity between hot components and their heat sinks. The gap filler’s minimal silicone content makes it suitable for use in silicone-sensitive applications including medical electronics, laser optics and telecommunications where silicone-based outgassing can lead to contamination and condensation issues or leave oily residues that interfere with process applications. The TP-S3 family of materials was developed by Chang Sung Corp. and is manufactured by Dongyun Electronics in South Korea.

Pads of TP-S3LS material are soft and compliant for easy compression and filling of air gaps between between irregular mating surfaces. The material’s Shore 00 hardness is 55. TP-S3 pads can be used in temperatures up to 200°C, which exceeds the use range of silicone-free gap fillers. The material has a UL 94 flame class rating of V-0. Its dielectric breakdown voltage is over 5.0 kV.

New TP-S3 gap filler material is available in 210 x 297 mm (8.3 in x 11.7 in) sheets or die-cut parts. Standard sheet thicknesses range from 0.5 to 5.0 mm (0.020 in to 0.196 in). Pricing for standard flat TP-S3LS sheets starts at $0.10 per square inch, which is below the cost of other 3.0 W/mK thermal gap fillers now available. Lower priced TP-S materials are also available with thermal conductivities of 2.0 and 1.0 W/mK.

Introducing Keratherm KL 90 and KL 91

Mounting Tape Provides up to Three Times the Thermal Conductivity of Competing Tapes

MH&W International has introduced Keratherm® KL 90 highly thermally conductive, double-sided adhesive tape which provides 1.4 W/mK of thermal conductivity – nearly three times higher than other thermal tapes – for more effective heat transfer from hot components to heat sinks. The new tape’s thermal impedance is just 208°C-mm2/W (0.32°K-in2/W).

Keratherm KL 90 tape consists of a ceramic-filled acrylic adhesive film that provides exceptional bonding properties, and replaces the use of mechanical fasteners, reducing costs and assembly time. A fiberglass-reinforced version, KL 91, is available for applications requiring higher levels of ruggedness, peel strength, and conformability to irregular surfaces. Both Keratherm KL 90 and KL 91 mounting tapes are silicone-free, eliminating any contamination concerns. If necessary, the tapes can be cleanly removed using a thin-edge blade.

Keratherm KL 90 double-sided adhesive tape is supplied on 400 mm (15.75 in) wide rolls, and is also available in custom die-cut shapes. Its standard material thickness is 0.300 mm, (0.012 in). KL 90 tape pricing starts at $0.22 per square inch in high volume orders. Developed and manufactured by Kerafol, a world leader in thermal interface material innovation, complete information on Keratherm KL 90 thermal adhesive tape can be found at www.mhw-thermal.com.

Silicone-Free Interface Material Provides High Thermal Conductivity

MH&W International has introduced Keratherm U 90 thermal interface material, manufactured by Kerafol, for use where contamination concerns prohibit the use of silicone-based thermal pads, but where high levels of thermal conductivity are needed for sufficient thermal transfer in hot electronic devices.

U 90 material consists of a ceramic-filled polyurethane film with thermal conductivity of 6.0 W/mK and thermal impedance of just 0.05 Kin2/W. The material has a high voltage breakdown property of 4.0 kV. It provides strong perforation protection with a tensile strength of 2.5 N/mm2 and a Shore A hardness of 70.

Typical applications for silicone-free U 90 thermal interface pads include medical devices, laser equipment, lighting systems, solar energy, disk drives and aerospace electronics.

MH&W’s Keratherm U 90 interface material is available in 0.100 and 0.200 mm thicknesses (3.9 and 7.8 mil). Standard and custom shapes are available in continuous rolls for automated or manual application. Pricing for U 90 thermal interface pads starts at $0.15 for 1 inch square, 0.200 mm thick pads in high volume quantities.

U 90 silicone-free thermal interface materials are part of Kerafol’s Keratherm line of thermally conductive interface materials. More information on U 90 pads can be found at www.mhw-thermal.com or by calling 1-201-891-8800 for samples and quotes.

Choosing Thermal Interface Materials

Knowing Your Application Needs is Key to Picking the Best TIM

As component powers continue to grow, so do their cooling requirements. One rule of thumb says that for every 10°C rise of the junction temperature the failure rate doubles. Thus, there is an urgent need to remove heat from hot chips to the surrounding air stream. Demand has led to a variety of new thermal management systems. But nearly all of these continue to use thermal interface materials, or TIMS, to effectively provide heat flow across the mating interfaces of cooling systems.

The essential purpose of TIMs is to maintain effective transfer of heat from hot chips to dissipating devices such as heat sinks or spreaders. As heat flows, it encounters thermal resistances that impede overall heat transfer. TIMs reduce the most problematic of these, the contact resistance between the mating parts (heat source – heat sink). Air gaps significantly limit heat flow from the hot component into the sink or spreader. An effective TIM replaces the gaps created by the non-smooth mating surfaces with a material whose thermal conductivity is much greater than that of air. Basically, it replaces poor conduction from point contacts and air to enhanced conduction through solids.
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