Machined or Skived: Choosing How a Copper Heat Sink Is Made
September 26, 2026
A copper fin pack can be cut or it can be peeled. Which one you order changes the price more than any other decision on the drawing, and a shop that only does one of them will not always tell you.
How each one works
Machining. A cutter removes material between fins, pass by pass. The fin geometry is limited by cutter size and reach, which is why aspect ratio drives the cost so hard.
Skiving. A blade shaves a thin layer partly through the block and bends it upright, leaving it attached at the base. Repeat, and you have a fin pack formed from the parent metal with no joint. Fins can be very thin and very close together.
Bonded fins are a third route, separate fins joined to a base, and they matter for very tall or very thin fins. This article is about the first two.
Where each one wins
| Machined | Skived | |
|---|---|---|
| Prototypes and low volume | Wins | Setup makes it expensive |
| Plain straight fin pack at volume | Slow, cost scales with fin count | Wins |
| Fin thickness and density | Limited by cutter | Very thin, very dense |
| Aspect ratio | Cost climbs past about 10 to 1 | High ratios are normal |
| Integrated features, bosses, channels | Wins, one piece | Not in the fin area |
| Irregular outline, angled fins | Wins | No |
| Base flatness | Machined, tight | Machined afterwards, tight |
| Cold plate with internal channels | Machined base, brazed | Hybrid, skived fins on a machined base |
The honest cost shape
Machining cost scales with the number of fins and the number of passes per fin. Double the fin count and the machining time roughly doubles. Push the aspect ratio past about 10 to 1 and it rises faster than that.
Skiving carries a setup and tooling cost that does not care much about fin count, then a per piece cost that is low. So at one piece machining wins easily, and at some quantity the lines cross. Where they cross depends on the fin pack, which is why the right move is to ask for both prices at your real quantity.
What drives the cost of busbars and heat sinks goes through the machining side line by line.
Where people go wrong
Ordering a production fin pack machined. Usually because the prototype was machined and nobody revisited it. If the fins are plain and straight and the quantity is real, get a skiving quote.
Ordering a one-off skived. The setup cost lands on one part.
Designing a machined fin pack around skived fin density. Very thin dense fins are normal for skiving and expensive for machining. Decide the process before you freeze the fin geometry.
Ignoring the hybrid. A skived fin pack on a machined base with bosses, cutouts and a flat interface face is common and often the cheapest answer for a real product.
What to put in the RFQ
- Fin thickness, gap, height and count
- Base features: bosses, holes, channels, interface face flatness and finish
- Real quantity, and whether it repeats
- A line saying you are open to either process, if you are
Then compare the two quotes honestly. If a shop tells you your production part should be skived rather than machined, that shop is being useful. The design side is covered in how to design a machined copper heat sink and the service page is copper heat sink and cold plate machining.
Frequently asked questions
Is a skived heat sink weaker than a machined one?
The fins are formed from the parent block, so there is no joint and no bond to fail. Skived fins are thin and can be bent by handling, which is a design and packaging question rather than a strength one.
Can a skived heat sink have mounting bosses or channels?
Not in the fin area. Skiving produces a plain fin pack. Bosses, cutouts and channels in the base are usually added by machining afterwards, which is a hybrid and often the right answer.
At what quantity does skiving become cheaper?
There is no fixed number, because it depends on fin count and aspect ratio. As a rough shape of the curve, machining is cheaper for a handful of pieces and skiving takes over somewhere in the tens to hundreds for a plain fin pack. Ask for both prices at your real quantity.
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