What are folded fin Heatsinks?

Originally developed by the military for aerospace applications in Airplanes and Satellites, requiring high fin densities and surface areas at a low weight, folded fin technology is used in various fields today. Folded fins are created by folding a continuous strip of aluminum or copper in a square wave pattern. One end of the folded fins are then brazed, soldered or glued to the Heatsink base using thermal conductive epoxy. Since the Heatsink fins and Base can be made out of different materials, customers can tailor a design and choose from a wide range of material and alloy combinations to achieve the optimum price/performance/weight ratio. Thanks to diffusion bonding, although expensive, the largest disadvantage, reduced thermal conductivity at the fin/base joints, can now be overcome.

Advantage:
  • Lightest weight of all heat sink manufacturing methods 
  • Allows the thinnest fins (down to 0.1 mm thick)
  • Allows more fins per inch of width
  • Minimized mounting base thickness
  • Maximum surface area per cubic volume for heat dissipation
  • Very high aspect ratios
  • Fins and base can be made out of different metals (copper base, aluminum fins)

Disadvantage:
  • Requires joints which reduce thermal conductivity (diffusion bonded folded fin heatsinks offer much improved conductivity)
  • More costly than skived fins or extrusion
  • Some materials (aluminum) require nickel plating to allow soldering


Comparison
Die casting
Extrusion
Stacked fin
Folded fin
Skived fin
Cost
medium to low
low
high
medium
low
Tooling Lead-Time
long
short
long
long
medium
Weight
medium
heavy
light
light
medium
Performance
high
limited
best
medium
limited