Guides / Materials

Stainless and Nickel Alloys in Semiconductor Hardware

September 21, 2026

Stainless is the default for anything in a semiconductor tool that meets chemistry, moisture or a vacuum boundary. The choices inside that word decide corrosion behaviour, particle performance and how much the part costs to make.

Choosing between the common grades

304 and 304L. General structural stainless. Fine for frames, covers and brackets. Not the choice for chlorides, for electropolished surfaces or for a vacuum boundary in a demanding process.

316L. The workhorse for gas lines, chamber hardware and anything wet. The molybdenum improves pitting resistance, the low carbon protects the weld zone. It electropolishes to a clean and stable surface, which is why gas wetted parts are usually specified in it.

Nickel alloys such as Hastelloy C-276. For chemistry that eats stainless. They are expensive, they work harden quickly, they need rigid setups, sharp tools and slow feeds and the material itself often has a long lead time. Few shops in any country take this work casually, and fewer still in Vietnam.

What these materials do to the machining

Property	Effect on the job
Work hardening	A dwelling tool creates a hard layer that ruins the next pass. Constant feed matters more than speed
Low thermal conductivity	Heat stays in the cutting zone, so tool life drops and coolant strategy matters
Galling on threads	Threads and sliding fits need the right lubricant and sometimes a different material pair
Weld distortion	Sealing faces are finish machined after welding, never before

The practical result is that stainless parts take longer per cubic centimetre than aluminum and nickel alloys take several times longer again. That time, not the price per kilo, is usually what makes the quote.

Passivation and electropolish are not the same thing

Passivation is a chemical treatment that removes free iron and restores the passive layer. It changes almost nothing dimensionally and is inexpensive.

Electropolish removes metal, smooths the surface and improves cleanability. It changes dimensions, softens sharp edges and needs a qualified supplier to be repeatable. Details are in hard anodize or electropolish.

Many drawings need both: electropolish on the wetted surface, passivation as the final treatment after any later machining.

Local availability is part of the decision

In Vietnam, 304 and 316L in common plate and bar sizes are readily available. Specific melt practices, certified low sulphur material and nickel alloys usually come by import with weeks of lead time. If your part needs one of those, say so in the RFQ and expect the material, not the machining, to set the schedule. The sourcing implications are covered in what to check before you send a drawing to Vietnam.

To get quotes where the material lead time is stated rather than assumed, send the RFQ with the grade, the certificate requirement and the finish in it.

Frequently asked questions

Is 316L always better than 304?

For anything wet, in contact with chlorides or destined for electropolish, yes. For a dry structural bracket, 304 is cheaper and works. The L means low carbon, which matters when the part is welded and then has to resist corrosion at the weld.

When does a nickel alloy become necessary?

When the chemistry attacks stainless: hot halogen gases, strong acids, some plasma environments. Hastelloy and similar alloys cost several times more, machine slowly and need a supplier who has cut them before.

Why does passivation appear on so many drawings?

Machining smears iron across the surface, which then corrodes and generates particles. Passivation removes the free iron and restores the chromium oxide layer. It is cheap, fast and worth requiring on any wet or vacuum facing stainless part.

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