Below are the most frequently asked questions about controlled expansion alloys (CE alloys). If you don't find the answer to your question, please contact us.
What are Osprey® CE alloys?
These are a family of controlled expansion, lightweight alloys composed of silicon-aluminum that have been specially developed to expansion match a range of low expansion metals and ceramics to satisfy a range of high-tech applications.
What does Sandvik supply in the area of CE alloy products?
Our main business in this area is the supply of machined (and electroplated) components. We will also supply packages that include feedthrough but this is carried out in conjunction with qualified partner companies.
What advantages do CE alloys offer?
CE alloys possess a unique combination of physical properties – low density (less than aluminium), high thermal conductivity and high specific stiffness, together with selectable expansion coefficients in the range 5 to 17 ppm/°C. At the same time, they lend themselves to standard methods of manufacture, including machining and plating.
How do CE alloys differ from Al-SiC?
CE alloys are true metal alloys of silicon and aluminium, whereas Al-SiC (Aluminium-Silicon Carbide) is a metal matrix composite of hard silicon carbide particles in a matrix of aluminium. Al-SiC is very difficult to machine and plate, in contrast to CE alloys which are much more amenable to these and other manufacturing operations.
What is the cost of CE alloy products?
The cost of CE alloy products is dependent on the size and shape of items. In general, it is similar to Kovar* and cheaper than copper-tungsten (Cu-W) and copper-molybdenum (Cu-Mo).
*Kovar is a trademark of CRS Holding.
Do CE alloys present any health hazards in the manufacture and in use?
No, CE alloys are environmentally friendly materials, being composed of the two most common elements present in the ground – aluminium and silicon. This distinguishes them from other materials that are used in similar high-tech applications, such as beryllium (Be), beryllia (BeO) and nickel (Ni).
Are CE alloys hermetic (leak-tight)?
CE alloy parts are normally hermetic down to thicknesses of 1 mm.
What is the maximum size of a part that can be supplied in CE alloys?
CE alloy parts can typically be supplied up to 50 cm (20 inches) in length and breadth, but larger sizes are available on request. Contact us with your requirements.
How easy is it to machine CE alloys?
All CE alloys can be readily CNC machined at Sandvik using proprietary technology developed by Sandvik.
What tolerances and surface finishes can be achieved?
The absolute tolerances which we can supply to will be dependent on the size of the part and the machining method used. For CNC machining, tolerances better than ± 0.05 mm are possible. With EDM, these are typically ± 0.02 mm. Flatness to within 1 in 1000 is usual. Surface finishes after milling are normally to Ra < 1μ, but with lapping this can be improved to Ra < 0.4μ.
How easy is it to place CE alloys with various metals?
All CE alloys can be plated with a wide range of metals, including nickel, copper, silver and gold using industry-standard processes developed for aluminium, and taking due care to follow procedures specified by Sandvik. Several plating companies are qualified to plate CE alloys.
Is it possible to insert feedthroughs into CE alloys and, if so, what types?
A variety of different types of feedthroughs can be inserted into CE alloy parts as per aluminium packages.
What are typical delivery lead times for CE alloy products?
Prototype components machined and plated to customer geometries and specifications typically take 3–5 weeks to deliver. However, if the parts need feedthroughs inserted, longer timescales should be allowed for. Contact us with your requirements.
For what applications are the CE alloys currently being used?
Well-developed applications of CE alloys include:
- Hermetic packages
- Microwave and RF housing, carries and heat sinks
- Optical and opto-elecronic housings
- Carrier plates for laminate PCBs
- Guide bars for PCBs
- Carriers for gas sensors
- Heat sinks and heat spreaders
- Semiconductor processing equipment components
- Soldering assembly fixtures (e.g. for BGA soldering of modules)
- Structural parts in pick and place equipment (e.g. wire-bonders)