E-Material
Encyclopedia
E-Material, also called E Material, is a metal matrix composite
consisting of beryllium
matrix with beryllium oxide
particles. It has high thermal conductivity
(210-230 W/m K), and its thermal expansion
can be adjusted to match other materials, e.g. silicon
and gallium arsenide chips and various ceramic
s. It is chiefly used in microelectronics
as substrate
for power semiconductor device
s and high density multi-chip module
s, where it aids with removal of waste heat
. E-materials have low weight and high strength, making them especially suitable for aerospace
technology. Their high elastic modulus
is favorable for absorbing vibrations and lowering material fatigue of attached modules and wire bonds.
Several variants exist:
E-materials are prepared by impact grinding and then hot isostatic pressing
into a block. The block is then sliced to cards, sawn to required shape, polished, machined, and optionally plated with e.g. nickel
, cadmium
, chrome
, silver
, copper
, or gold
. Without coatings, the corrosion
resistance of E-materials is similar to aluminium.
E-materials are used in aerospace
technology, e.g. as laminated multi-chip module
s in Iridium
and Globalstar
satellites, as heat sink
s, and in avionics
of F-22 Raptor
, F-16 Fighting Falcon
, F/A-18 Hornet
, and the Joint Strike Fighter. It is also used in SEM-E modules and printed wiring boards.
Care has to be taken during machining and handling of E-materials, as beryllium and its compounds are toxic.
Gold-tin and gold-germanium alloys can be used for brazing
with kovar
or CuMo and other electronics packaging alloys.
A similar material is Dymalloy
, with copper-silver alloy instead of beryllium and diamond
instead of beryllium oxide, or AlSiC
, aluminium
with silicon carbide
. Other materials are copper reinforced with carbon fiber
, diamond-reinforced aluminium, reinforced carbon-carbon
, and pyrolytic graphite.
Another similar material is AlBeMet®, a metal-matrix composite of aluminium and beryllium.
Metal matrix composite
A metal matrix composite is composite material with at least two constituent parts, one being a metal. The other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite...
consisting of beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...
matrix with beryllium oxide
Beryllium oxide
Beryllium oxide , also known as beryllia, is an inorganic compound with the formula BeO. This colourless solid is a notable electrical insulator with a higher thermal conductivity than any other non-metal except diamond, and actually exceeds that of some metals. As an amorphous solid, beryllium...
particles. It has high thermal conductivity
Thermal conductivity
In physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction....
(210-230 W/m K), and its thermal expansion
Thermal expansion
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are rare; this effect is...
can be adjusted to match other materials, e.g. silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
and gallium arsenide chips and various ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s. It is chiefly used in microelectronics
Microelectronics
Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture of very small electronic components. Usually, but not always, this means micrometre-scale or smaller,. These devices are made from semiconductors...
as substrate
Substrate (semiconductor)
Substrate is a solid substance onto which a layer of another substance is applied, and to which that second substance adheres. In solid-state electronics, this term refers to a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide , an alloy...
for power semiconductor device
Power semiconductor device
Power semiconductor devices are semiconductor devices used as switches or rectifiers in power electronic circuits . They are also called power devices or when used in integrated circuits, called power ICs....
s and high density multi-chip module
Multi-Chip Module
A multi-chip module is a specialized electronic package where multiple integrated circuits , semiconductor dies or other discrete components are packaged onto a unifying substrate, facilitating their use as a single component...
s, where it aids with removal of waste heat
Waste heat
Waste heat sometimes called Secondary heat or Low-grade heat refers to heat produced by machines, electrical equipment and industrial processes for which no useful application is found. Energy is often produced by a heat engine, running on a source of high-temperature heat...
. E-materials have low weight and high strength, making them especially suitable for aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
technology. Their high elastic modulus
Elastic modulus
An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substance's tendency to be deformed elastically when a force is applied to it...
is favorable for absorbing vibrations and lowering material fatigue of attached modules and wire bonds.
Several variants exist:
- E-20, containing 80 vol.% of beryllium and 20 vol.% (25.8-32.25 w.%) beryllium oxide. Its thermal conductivity is 210 W/(m·K). Its thermal expansion coefficient is 8.7. Its density at 25 °C is 2.045 g/cm3.
- E-40, containing 60 vol.% of beryllium and 40 vol.% (49.5-54.8 w.%) beryllium oxide. Its thermal conductivity is 220 W/(m·K). Its thermal expansion coefficient is 7.5. Its density at 25 °C is 2.277 g/cm3.
- E-60, containing 40 vol.% of beryllium and 60 vol.% (69.4-73.2 w.%) beryllium oxide. Its thermal conductivity is 230 W/(m·K). Its thermal expansion coefficient is 6.1. Its density at 25 °C is 2.513 g/cm3.
E-materials are prepared by impact grinding and then hot isostatic pressing
Hot isostatic pressing
Hot isostatic pressing is a manufacturing process used to reduce the porosity of metals and influence the density of many ceramic materials. This improves the material's mechanical properties and workability....
into a block. The block is then sliced to cards, sawn to required shape, polished, machined, and optionally plated with e.g. nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
, chrome
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
, silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, or gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
. Without coatings, the corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
resistance of E-materials is similar to aluminium.
E-materials are used in aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
technology, e.g. as laminated multi-chip module
Multi-Chip Module
A multi-chip module is a specialized electronic package where multiple integrated circuits , semiconductor dies or other discrete components are packaged onto a unifying substrate, facilitating their use as a single component...
s in Iridium
Iridium (satellite)
Iridium Communications Inc. is a company, based in McLean, VA, United States which operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units...
and Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
satellites, as heat sink
Heat sink
A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...
s, and in avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
of F-22 Raptor
F-22 Raptor
The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation supermaneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals...
, F-16 Fighting Falcon
F-16 Fighting Falcon
The General Dynamics F-16 Fighting Falcon is a multirole jet fighter aircraft originally developed by General Dynamics for the United States Air Force . Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft. Over 4,400 aircraft have been built since...
, F/A-18 Hornet
F/A-18 Hornet
The McDonnell Douglas F/A-18 Hornet is a supersonic, all-weather carrier-capable multirole fighter jet, designed to dogfight and attack ground targets . Designed by McDonnell Douglas and Northrop, the F/A-18 was derived from the latter's YF-17 in the 1970s for use by the United States Navy and...
, and the Joint Strike Fighter. It is also used in SEM-E modules and printed wiring boards.
Care has to be taken during machining and handling of E-materials, as beryllium and its compounds are toxic.
Gold-tin and gold-germanium alloys can be used for brazing
Brazing
Brazing is a metal-joining process whereby a filler metal is heated above and distributed between two or more close-fitting parts by capillary action. The filler metal is brought slightly above its melting temperature while protected by a suitable atmosphere, usually a flux...
with kovar
Kovar
Kovar is a nickel-cobalt ferrous alloy designed to be compatible with the thermal expansion characteristics of borosilicate glass in order to allow direct mechanical connections over a range of temperatures...
or CuMo and other electronics packaging alloys.
A similar material is Dymalloy
Dymalloy
Dymalloy is a metal matrix composite consisting of 20% copper and 80% silver alloy matrix with type I diamond. It has very high thermal conductivity of 420 W/, and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips...
, with copper-silver alloy instead of beryllium and diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
instead of beryllium oxide, or AlSiC
AlSiC
AlSiC, pronounced "alsick", is a metal matrix composite consisting of aluminium matrix with silicon carbide particles. It has high thermal conductivity , and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips and various ceramics...
, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
with silicon carbide
Silicon carbide
Silicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...
. Other materials are copper reinforced with carbon fiber
Carbon fiber
Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...
, diamond-reinforced aluminium, reinforced carbon-carbon
Reinforced carbon-carbon
Carbon fibre-reinforced carbon is a composite material consisting of carbon fibre reinforcement in a matrix of graphite. It was developed for the nose cones of intercontinental ballistic missiles, and is most widely known as the material for the nose cone and wing leading edges of the Space Shuttle...
, and pyrolytic graphite.
Another similar material is AlBeMet®, a metal-matrix composite of aluminium and beryllium.