| Q1: What beneficial
for cooling die-casting or extrusion and why?
A1: Extrusion is most beneficial than dye casting. Dye casting
is used only in 25 - 30 % of Aluminum alloy and the rest carbons and
other alloys. In dye cast always it happens for air gap area.
In extrusion use 70 % - 80% 0f aluminum alloy and 20 % carbon and
other alloys. Aluminum is extruded always in semi-solid form which
is made of above mentioned specified material and it is stretched
and pressurized by a heavy hydrolic pressing system and after all
the same is provided for edging.
Dye casting has 30% - 40% less transparency of heat than extrusion
due to excessive quantity of carbon in the material. In the same way
extruded aluminum heat sink has 30-40% more transparency due to purity
of excessive existence of pure aluminum alloy.
Q4: What difference does the color of the heatsink make?
A4: In natural convection a black or dark colored heatsink
will perform 3% to 8% better than an aluminum heatsink in its natural
silverish color. This is due to the fact that dark colors radiate
heat more efficiently. In forced air applications the color does not
add any performance due to the increase in convection.
Q5: What surface treatment should be applied to heatsinks?
A5: Many heatsinks are black or color anodized. This is because
of two reasons. 1.) It allows for the dark color to enhance the radiation
effects and 2.) It protects the aluminum in harsh environments. Salt
exposure is a good example. It is unnecessary in most electronic applications
other than natural convection.
Gold or yellow chromate is also used to provide surface protection.
It adds little or no radiation benefits.
Unfinished aluminum is typically used in most consumer applications
where thermal radiation and harsh environments are not factors