Spray forming, also called spray casting or spray deposition, is the inert gas atomization of a liquid metal stream into variously sized droplets (10-500 microns) that are then propelled away from the region of atomization by the fast flowing atomizing gas. The droplet trajectories are interrupted by a substrate which collects and solidifies the droplets into a coherent, near fully dense preform. By continuous movement of the substrate relative to the atomizer as deposition proceeds, large preforms can be produced in a variety of geometries including billets, tubes and strip at flow rates of 5-30kg/min.

Spray formed Si-Al alloys for electronic packaging applications

Alloys containing up to 70wt%Si are being manufactured by spray forming. These alloys offer a unique combination of low thermal expansion, high thermal conductivity and low density, and are under investigation for electronic package thermal management applications in the avionics, satellite and other industries. The research concerns the characterisation of the key mechanical and microstructural properties of Al-70Si alloy(AlSi70 alloy in China); the optimisation of spray forming; and the enhancement of alloy properties by ternary alloy additions and novel variants of the spray forming process.

Baienwei Co.,Ltd manufactures range of low expansion Al-Si alloys:

■ AlSi25,AlSi40,AlSi50,AlSi60,AlSi70,AlSi80.

These advanced alloys(Al-Si alloys) have the unique combination properties,such as:

■ Adjustable CTE:

Controllable CTE, in the range of 17-7ppm/℃.

 Lightweight:

■ 10% lightweight than pure aluminum;

■ 25% the weight of Cu-Mo;

■ 55% the weight of Titanium.

Good thermal conductivity:

■ AlSi alloys = 120/175 W/m-K;

■ BEW 6061(T6) =210. 

Ease of platable and machinable

Environmentally friendly