FAQ about Osprey controlled expansion alloys
Below are the most frequently asked questions about Osprey controlled expansion (CE) alloy products.
- What do Sandvik supply in the area of CE alloy products?
- What advantages do CE alloys offer?
- How do CE alloys differ from Al-SiC?
- What is the cost of CE alloy products?
- Do CE alloys present any health hazards in manufacture and in use?
- Are CE alloys hermetic (leak-tight)?
- What is the maximum size of part that can be supplied in CE alloys?
- How easy is it to machine CE alloys?
- What tolerances and surface finishes can be achieved?
- How easy is it to plate CE alloys with various metals?
- Can housings and packages of CE alloys be laser-welded?
- Is it possible to insert feedthroughs into CE alloys and, if so, what types?
- How easy is it to produce threaded holes in CE alloys?
- What are typical delivery lead times for CE alloy products?
- For what applications are the CE alloys currently being used?
These are a family of controlled expansion lightweight alloys composed of silicon-aluminium that have been specially developed to expansion match a range of low expansion metals and ceramics to satisfy a range of high-tech applications.
Sandvik's main business in this area is the supply of machined (and electroplated) components. Sandvik will also supply packages which include feedthrough but this is carried out in conjunction with qualified partner companies.
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.
CE alloys are true metal alloys of silicon and aluminium, whereas Al-SiC is a metal matrix composite of hard silicon carbide particles in a matrix of aluminium, making the latter very difficult to machine and plate, in contrast to CE Alloys which are much more amenable to these and other manufacturing operations.
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 and copper-molybdenum.
No, CE alloys are environmentally friendly materials, being composed of the two most common elements present in the ground – aluminium and silicon – and this distinguishes them from other materials that are used in similar high-tech applications, such as beryllium, beryllia and nickel.
CE alloy parts are normally hermetic down to thicknesses of 1 mm.
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.
All CE alloys can be readily CNC machined at Sandvik using proprietary technology developed by Sandvik.
The absolute tolerances which Sandvik 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, but 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.
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.
Housings and packages in CE17, CE13 and CE11 Alloys can be readily laser-welded with CE alloy lids. For information on welding CE7 and CE9. Contact us for details.
A variety of different types of feedthroughs can be inserted into CE alloy parts as per aluminium packages.
It is possible to produce threaded holes down to 1.8 mm diameter (UNC 256), by thread milling or tapping. Contact us for further details.
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.
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)
* Kovar is a trademark of Carpenter Technology Corporation
SIS for CE alloys