Semiconductor Parts Sourcing Glossary

66 terms, defined for the person buying or quoting the part rather than for the process engineer running the tool.

Each definition says what the term changes about a quote, a drawing or an inspection. Where a guide covers it properly, the entry links to it.

Part families

Burn in board: A board that holds many devices at temperature for reliability testing. The machined content is the frames, stiffeners and socket plates around it.
Change kit: The set of nests, pockets, guides and plates that lets one test handler run a different package. An assembly, so it is only as fast as its slowest item. Read the guide.
Chuck: The surface that holds the wafer during processing, by vacuum or electrostatic force. Flatness on a chuck is held far tighter than on ordinary hardware.
EFEM: Equipment front end module. The atmospheric section of a tool where wafers are loaded and handed to the vacuum side. Its brackets, mounts and covers are common machined work in anodized aluminum.
End effector: The blade or paddle on a robot arm that carries the wafer. Edge quality and flatness under load matter more than headline tolerance, because a burr here is a particle source directly above the product. Read the guide.
Gas distribution plate: A perforated plate that spreads gas evenly across the wafer. Hole count, hole quality and burr control decide whether it works.
Gas stick: An assembled line of valves, regulators and fittings that delivers one process gas. The machined content is the manifold blocks and mounting hardware. Read the guide.
Lift pin: A small pin that raises the wafer off a chuck so the robot can pick it up. Usually ceramic or coated, and a wear item, which makes it a repeat order.
Load port: The interface where a wafer carrier docks to the tool. Its hardware combines moderate tolerance with cleanroom material requirements.
Nest: The pocket that holds a device during handling or test. Too tight and devices jam, too loose and they sit crooked.
Process chamber: The vessel where the wafer is processed under vacuum. Machined from aluminum or stainless, usually welded then finish machined and judged on leak rate and sealing face quality. Read the guide.
Showerhead: The common name for the gas distribution assembly above the wafer. Machined as a precision plate stack with very high hole counts.
Susceptor: The heated support that carries the wafer in a deposition or thermal process. Flatness and thermal uniformity drive the specification.
Test socket hardware: The machined plates and frames that locate a device against the contactor during test. The tightest features on the part are the ones that set pitch. Read the guide.
Weldment: A frame or base welded from plate and section, then stress relieved and finish machined. Common for tool frames, and work Vietnamese shops are generally strong at.

Materials

Alumina: A technical ceramic used where stiffness, temperature or particle performance justify it. Ground and lapped rather than milled, with few local suppliers.
Aluminum 6061: The default alloy for semiconductor hardware. Machines predictably, welds, anodizes cleanly and is stable once stress relieved. Read the guide.
Aluminum 7075: Stronger than 6061 but it does not weld well, corrodes more easily and anodizes darker because of its copper content. Chosen for stiffness, not for process facing surfaces. Read the guide.
Cast tooling plate: Cast and stress relieved aluminum plate sold flat and ready to machine, sold under names such as Mic 6. Costs more per kilo and buys flatness. Read the guide.
Hastelloy C-276: A nickel alloy for chemistry that attacks stainless. Expensive, slow to machine, work hardens quickly and usually carries a long material lead time. Read the guide.
PEEK: A high performance polymer used for insulators, guides and device contact parts. Available unfilled, glass filled, carbon filled and in static dissipative grades. Read the guide.
Silicon carbide: A ceramic with high stiffness and thermal stability used in handling and thermal hardware. Long lead time and a specialist supply chain.
Stainless 316L: The workhorse for wet, vacuum and gas wetted hardware. The low carbon content protects corrosion resistance at the weld, and it electropolishes to a stable surface. Read the guide.
Static dissipative grade: A polymer formulated to bleed charge away in a controlled time rather than insulate or conduct. Specified by a surface resistance range, not by the phrase ESD safe. Read the guide.
Stress relief: A thermal or mechanical step that releases internal stress in plate before finish machining, so the part does not move after it is unclamped. Read the guide.
Torlon: A PAI polymer, very strong and stiff for a plastic, common in test socket hardware. Needs a proper cure schedule and sometimes post machining conditioning. Read the guide.
Vespel: A polyimide with high temperature capability and good dimensional behaviour under load. Expensive, and stock shapes are limited, so the design has to suit what can be bought. Read the guide.

Finishes and treatments

Bead blast: A uniform matte texture produced by blasting media. Used before anodize for appearance, and sometimes to control reflection inside an optical path.
Electropolish: An electrolytic process that removes metal from stainless, smooths the surface and improves the passive layer. It changes dimensions and softens sharp edges. Read the guide.
Masking: Protecting a feature so it receives no coating. Hand work, repeated per piece and the most common cause of threads that will not accept a screw after anodize. Read the guide.
Passivation: A chemical treatment that removes free iron smeared across a machined stainless surface and restores the chromium oxide layer. Cheap, quick and worth requiring on wet parts. Read the guide.
Rack mark: The small uncoated point where a part hung during a bath process. Harmless unless it lands on a sealing or cosmetic surface, so its location should be specified.
Type II anodize: Clear or coloured anodic coating on aluminum, roughly 5 to 25 microns, chosen when appearance and mild corrosion resistance matter more than wear. Read the guide.
Type III hard anodize: A thick, hard anodic coating, commonly 25 to 50 microns on this hardware. It grows roughly half into the metal and half out, so threads and bores need masking or a pre finish size. Read the guide.

Cleanliness and vacuum

Cleanroom packing: Cleaning, drying and double bagging so the inner bag can be opened inside the controlled area. It is labour and consumables, not a free extra on a quote. Read the guide.
Dead volume: In a gas line, a pocket where gas lingers and releases into a later step. It shows up as slow purge and cross contamination, and it is designed out, not polished out. Read the guide.
Double bagging: Two sealed bags, the outer removed at the airlock and the inner carried inside. It only works when the shop understands why the inner bag was sealed in a clean area. Read the guide.
Helium leak test: The normal method for proving a vacuum boundary, quoted as a leak rate. Specify the rate and the method, and require the test after the final finish. Read the guide.
ISO 14644 class: The standard that defines air cleanliness by particle count per cubic metre. It describes a room, not your part, which is why a class number alone is a weak drawing requirement. Read the guide.
Outgassing: Gas released slowly from a surface or material under vacuum, raising base pressure. Usually water, machining fluid or handling residue rather than the material itself. Read the guide.
RGA test: Residual gas analysis. Puts the part under vacuum and measures which species come off. A qualification and troubleshooting tool, not a receiving inspection for every piece. Read the guide.
Trapped volume: A pocket behind a fit, under a screw head or inside an unvented hole where gas sits and releases later. A design problem that no cleaning process fixes. Read the guide.
Vented screw: A fastener with a drilled path so gas cannot be trapped under the head in a vacuum assembly. A small detail that prevents a slow pump down.

Tolerance and metrology

CMM: Coordinate measuring machine. Produces the dimensional report behind a first article. Its presence proves capability only when calibration and method are documented.
Cutoff length: The sampling length used when measuring roughness. A roughness number reported without it cannot be compared with anyone else’s number. Read the guide.
Datum scheme: The set of references that tells the shop how to hold, measure and use the part. Without one, the shop chooses its own, which is rarely the one the assembly uses. Read the guide.
Flatness: A form control describing how far a surface deviates from a perfect plane. It is a separate requirement from thickness tolerance, and it needs a stated measurement condition. Read the guide.
Free state: A measurement taken with the part unconstrained, under its own weight. The opposite is a constrained measurement, which needs the bolt pattern and torque stated. Read the guide.
Parallelism: How closely one surface follows another, referenced to a datum. A plate can pass thickness everywhere and still fail parallelism. Read the guide.
Ra: Average surface roughness over a sampling length. It is not cleanliness, not flatness and it says nothing about the direction of the machining marks. Read the guide.
True position: A tolerance on where a feature sits relative to the datums, expressed as a zone rather than as plus or minus on two directions.

Documents and qualification

Ballooned drawing: A drawing with every dimension and note numbered so each one can be matched to a measured result. Without it an inspection report proves very little. Read the guide.
Concession: A written acceptance of a part that deviates from the drawing. Agreeing in advance who can sign one turns a two week argument into a one day decision.
Control plan: For a repeat part, the document that says which characteristics are checked, how often, with what instrument and what happens when one drifts. Read the guide.
FAI: First article inspection. A structured record that every characteristic on the drawing was checked, tied to a ballooned drawing and to the material and process certificates. Read the guide.
Material certificate: The mill document traceable to the lot the part was made from. The most common gap on subcontracted work is a certificate for a different lot. Read the guide.
PPAP: A production part approval package from the automotive world. Machined semiconductor hardware rarely needs the full package, so ask for the documents you will actually read. Read the guide.
Qualification lot: The pilot quantity run at the real process before production is released. Measure delivery as well as dimensions, because a shop that misses dates twice is a rework queue. Read the guide.

Commercial and sourcing

Drawing freeze: Agreeing that no revision is issued once an order is released. A change after programming restarts setup, fixturing and the first article. Read the guide.
Expedite: Paying to move up a queue. Worth asking which queue, because expediting at the machine shop and at the finisher are different things at different prices. Read the guide.
Front end and back end: Front end is wafer fabrication, back end is assembly, packaging and test. The distinction decides which part families and which documentation a buyer is dealing with.
Incoterm: The delivery term that fixes who pays for transport, insurance and customs at each stage. State it in the RFQ, because it moves the comparable price.
Lead preview: The anonymised summary a shop sees before taking a request: part family, material, size, quantity, tolerance, finish, packing and destination, with no buyer identity. Read the guide.
OSAT: Outsourced semiconductor assembly and test. The back end of the industry, and the segment Vietnam is built around, which shapes what parts are in steady local demand. Read the guide.
RFQ package: Everything a shop needs to quote: model, drawing, quantity, inspection scope, certificates, packing level and destination. Gaps in it are the main reason quotes are not comparable. Read the guide.
Second source: A second qualified supplier for the same part. Costs one extra qualification and removes the single point of failure that stops a line. Read the guide.

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