Microelectronic packages

1. Body materials

• Kovar – low expansion to minimize stress when substrates are mounted – closely matches commonly used materials such as GaA
• Alloy 42 – lowest cost per unit weight of material
• Alloy 48 - to match CTE of special thermal bases
• 300 series Stainless steel – to match CTE of special substrates
• Monel – suitable for soldering without additional plating
• Invar – near-flat CTE curve at soldering temperatures
• Aluminum – thermal conductivity, lightweight; machinable; weldable; - contacts are soldered in place
• Titanium (Ti6Al4V & CP) – lightweight; bio-compatible; weldable – can be direct sealed
• Copper – thermal conductivity
• Tungsten-Copper Composites – thermal conductivity; heat dissipation required
• Molybdenum-Copper Composites - thermal conductivity; heat dissipation required
• AlSiC – lightweight; thermal conductivity; heat dissipation required
• GlidCop – lightweight; thermal conductivity; heat dissipation required
• Brass – thermal conductivity; not directly sealed - contacts are soldered in place

2. Contact materials

• Kovar – for matched seals
• Copper cored Kovar – electrical conductivity
• Alloy 52 – for compression seals
• Copper cored Alloy 52 – electrical conductivity
• Copper – electrical conductivity; not directly sealed in
• Copper-Zirconium Composite – stiffness; conductivity
• GlidCop – conductivity