Artificial graphite is a unique engineered material that finds many uses in microelectronics assembly. SST International is starting a blog series which will explore the role graphite plays in thermal assembly processes.This is the first blog of their series.
WHY GRAPHITE?
Graphite has a number of properties which are well suited to high temperature use. These include a coefficient of thermal expansion (CTE) which matches many ceramics, glasses, and low-expansion rate metals. Graphite has one of the highest melting (actually sublimation) temperatures of any engineered material (>3600°C). It retains its mechanical properties at elevated temperatures and maintains its shape and form over multiple thermal cycles at high temperatures. Molten solder, brazing materials and even softened glass do not stick or adhere to graphite.
Resistive Graphite Tool for Hermetic Package Solder Sealing of MEMS IR Detectors
BRIEF HISTORY OF ARTIFICIAL GRAPHITE PRODUCTION
In the United States in the late 1800s, Edward Acheson developed and patented a process for manufacturing artificial graphite using a high temperature, resistively-heated electric furnace. He was actually trying to make diamonds. His work led to the building of the first commercial graphite plant in Niagara Falls, New York. Nearby hydroelectric plants could economically produce the power required for the very large electric furnaces.
Early on, the predominant use for artificial graphite was as crucibles to hold molten metals. It is used heavily in steelmaking, in batteries, in brake linings, and even pencils. Yet the quality of graphite for these uses is actually quite low.
In the late 1950s the needs of the space race drove the development of a material with the heat-resistant capabilities of ceramics, and the tensile strength of metal, to protect the nose cone of a re-entry vehicle. Engineers at Chance Vought Aircraft Research Center in Texas developed an artificial graphite material that met the requirements for space use, and found many more commercial applications. That development led to the birth of POCO Graphite, a company that developed markets for their materials in the semiconductor and electronics packaging industry.
MORE TO COME...
Look for future graphite blogs covering the topics of:
- How Artificial Graphite is Produced
- Electronics Grade Graphite Properties
- Machining and Post Processing of Graphite
- Unique Uses of Graphite in Microelectronic Assembly Processes
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David Muhs
President
SST International