OL1.SEP–TI–SC
Heat sink substrate saves machining costs
Heat sinks for high-performance applications have traditionally been
machined from materials containing ceramics or refractory metals that
provide good thermal properties, but are difficult (and thus expensive) to
machine. Texas Instruments' Metallurgical Materials Div.in Attleboro, MA,
has developed a new material, called Silvar, which can be machined at
costs typically 20% to 30% lower than traditionally refractory metals.
The material combines both nickel-iron alloys and silver. The nickel-iron
gives the material good thermal properties, while the silver provides high
thermal conductivity. The table compares performance characteristics of
the various metals. Texas Instruments hopes Silvar can replace standard
high-performance substrate materials such as copper-tungsten and
copper-molybdenum in heat sinks, heat spreaders, and other thermal
management substrates used in high-performance applications, such as
high-end PCs and workstations. Multichip-module substrates are another
possible application for the material. Texas Instruments plans to
custom-manufacture heat sinks and other heat management parts from the
material. Unlike refractory and ceramic metals, which tend to deform from
residual stresses, Silvar acts like a malleable metal. Thus it can be
rolled, stamped, forged, and drawn–operations not possible with the other
high-performance metals. In fact, the material can be formed to
tolerances which require costlier machining techniques on other materials
(see photo). Flatness tolerances of 0.001 to 0.002 in.can be achieved on
Silvar substrates as large as 3 x 1 in. For more information, contact
David Jordan of Texas Instruments, Metallurgical Materials Div.in
Attleboro, MA, at 508-699-3238, or . –Spencer Chin
CAPTION:
Silvar, a combination of nickel-iron alloys and silver, can be precision
machined to very fine tolerances for use in heat sinks and other thermal
management substrates.
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