A LAM Research or Tokyo Electron (TEL) OEM part number is a structured identifier in which each segment encodes specific information: a leading prefix that signals the part class or vendor group, a base number that names the component, and a trailing revision suffix that tracks engineering change. To look one up, decode the segments first, then cross-reference the base number against a qualified second-source catalogue while checking for any supersession that has replaced the original.
Why OEM part numbers need decoding on legacy fabs
On a 200mm tool that has been in service for fifteen or twenty years, the part number printed on a label, etched on a casting or quoted in a service manual is often the only reliable handle an engineer has on a component. The original purchase order is long gone, the OEM catalogue entry may be marked end-of-life, and the person who last ordered the part has moved on. Reading the number correctly is therefore the first step in every sourcing, repair or obsolescence decision.
An OEM part number is the manufacturer’s own canonical identifier for a component. It is not arbitrary. Both LAM Research and Tokyo Electron use segmented numbering schemes in which position carries meaning, so a number that looks like a random string actually tells a trained reader the part family, the controlled base component and the revision level. Once those segments are understood, the same number becomes the key that unlocks a cross-reference to a qualified second-source equivalent and a check against any later supersession.
SEMI, the international association for the semiconductor manufacturing supply chain, maintains the component standards and qualified-vendor practices that govern how these parts are produced and accepted. That framework matters here because a correctly decoded number is what lets a buyer confirm that a second-source part is genuinely equivalent in form, fit and function, rather than merely similar.
How do I look up a LAM or TEL part number?
Looking up an OEM part number is a four-step workflow. Each step narrows the search and reduces the risk of ordering the wrong revision or a part that has since been replaced.
- Capture the full number exactly. Record every digit and separator, including the revision suffix. A number transcribed without its suffix, for example dropping the final group from a LAM number, can map to several physically different parts.
- Decode the segments. Split the number on its hyphens and identify the prefix, the base number and the revision. The prefix tells you the part class; the base number is the stable identity you will search on; the revision tells you which engineering iteration you are holding.
- Cross-reference the base number. Search the base number, not the full string with revision, against a qualified parts catalogue or an obsolescence-aware distributor. Matching on the base number surfaces every revision and every equivalent SKU, which is what you want before you commit.
- Check for supersession. Confirm the number has not been superseded by a later part. OEMs replace components for cost, availability or reliability reasons and issue the original number’s replacement in change documentation. Ordering a superseded number can still work, but the supply chain may quietly ship you the successor, or nothing at all.
For deeper context on selecting and qualifying suppliers once you have the number, see the semiconductor spare parts sourcing guide, which covers vendor selection, lead time and qualification status in detail.
What does the part number prefix mean?
The prefix structure is the leading segment of the part number, and it is the single most useful piece of information for triage. It groups the part into a class before you know anything else about it. The two OEMs structure their numbers differently, so they are best read separately.
LAM Research part number structure
LAM Research part numbers are typically built from three hyphen-separated groups, in the pattern class–base–revision. A representative example is the form 853-039372-001:
| Segment | Example | What it encodes |
|---|---|---|
| Leading group (prefix) | 853 | Part class or vendor/commodity grouping, distinguishes, for example, a machined assembly from an electronic or consumable item |
| Base number | 039372 | The stable identity of the specific component; this is the field to search and cross-reference on |
| Revision suffix | 001 | Engineering revision / dash number; increments as the part is changed under revision control |
The practical takeaway is that the middle group, the base number, is the component’s true identity. The leading group helps you classify and route the request; the trailing group tells you which iteration you have. When you search, you search the base.
TEL (Tokyo Electron) part number structure
Tokyo Electron part numbers also use hyphen-separated groups, commonly in the form 2981-600503-12, where a leading family group precedes a base number and a short trailing revision or dash code. The reading logic mirrors LAM’s: a class-level prefix, a base identity, and a revision tail.
| Segment | Example | What it encodes |
|---|---|---|
| Leading group (prefix) | 2981 | Part family / commodity group on the platform |
| Base number | 600503 | The specific component identity used for search and cross-reference |
| Trailing group (revision) | 12 | Revision or dash code indicating the engineering iteration |
Because both schemes place the component’s true identity in the middle and the change history at the end, the same decoding habit works across both OEMs: separate on the hyphens, classify on the prefix, search on the base, verify on the revision.
Reading the revision suffix
The revision suffix (the trailing group, often called a dash number) records that the part has been changed under formal revision control. A higher suffix generally indicates a later iteration, but the suffix on its own does not tell you whether the change was fit-affecting. Some revisions are documentation-only or cosmetic; others alter a dimension, a material or an interface and are not backward-compatible.
Two rules keep this safe in practice:
- Never assume a higher revision is a drop-in replacement. Confirm interchangeability against the OEM change note or a qualified supplier’s equivalence statement before fitting a different revision to a running tool.
- Record the revision you actually fit. Closing the loop on which dash number is installed protects the next engineer and feeds an accurate spares list. LAM’s own process-of-record parts are released “under strict revision control, ” which is precisely why the suffix is worth tracking rather than discarding.
The cross-reference workflow
A cross-reference is a one-to-one mapping from an OEM part number to a qualified second-source SKU that is equivalent in form, fit and function. Building or using a cross-reference is how a fab consolidates its supply chain and defeats obsolescence without compromising on a qualified part.
The workflow is deliberately conservative:
- Search on the base number. Strip the revision and query the base identity so that every equivalent and every revision is visible.
- Confirm form, fit and function. A genuine cross-reference is FFF-equivalent: it matches the physical form, mates to the same interfaces, and performs the same function under the same conditions. A similar-looking part that misses on any of the three is not a cross-reference.
- Check qualification status. Establish whether the equivalent is already fab-qualified for production use. SEMI E10 reliability metrics, such as MTBF, inform how a second-source part’s performance is judged, and copy-exact and marathon-test practices govern qualification of the replacement.
- Record the mapping. A maintained 1:1 cross-reference table (OEM number to qualified SKU, with revision and qualification notes) turns one-off lookups into a reusable asset and shortens the next order.
| Cross-reference field | Why it matters |
|---|---|
| OEM base number | The stable search key; revision-independent |
| OEM revision held | Establishes the baseline you must match or supersede |
| Second-source SKU | The qualified equivalent you can actually buy |
| FFF confirmation | Evidence the equivalent matches form, fit and function |
| Qualification status | Whether the part is accepted for production |
| Supersession note | Any later OEM number that replaces the original |
Supersession: tracing a number that has been replaced
Supersession is the formal replacement of one part number by another. It is distinct from a revision change: a revision keeps the base number and increments the suffix, whereas a supersession retires a number and points to a different one. Both LAM and TEL issue supersessions when a component is redesigned, re-sourced or consolidated.
To trace a supersession:
- Check whether the number is still active with the OEM or a knowledgeable distributor before assuming it is obsolete. An apparently dead number is frequently alive under a successor.
- Follow the chain to the end. A number can be superseded more than once; the part you actually want is at the end of the chain, not the first hop.
- Treat a dead end as an obsolescence trigger. If the number is genuinely retired with no OEM successor, it has become an obsolescence problem, and the response is a last-time buy, a qualified second-source, or an upgrade rather than another fruitless search.
Worked lookups
The following worked examples show the decode-then-resolve habit applied end to end. Part numbers are illustrative of the formats, not catalogue quotations.
Worked example 1, a LAM-format number
Suppose an engineer reads 853-039372-001 from a chamber assembly on a LAM etch platform.
- Decode: class group 853, base 039372, revision 001.
- Search: query base 039372, ignoring the 001, to surface every revision and any equivalent.
- Resolve: confirm whether a qualified second-source maps 1:1 to base 039372 with an FFF statement, and check that 001 has not been superseded by a later number. Fit only after the revision and qualification status are confirmed.
Worked example 2, a TEL-format number
Suppose the number is 2981-600503-12 from a board on a TEL platform.
- Decode: family group 2981, base 600503, revision 12.
- Search: query base 600503 to see all revisions; note that 12 is the iteration in hand, not necessarily the latest.
- Resolve: confirm a qualified equivalent against the base, verify whether revision 12 is current or superseded, and record the mapping for reuse.
Worked example 3, a number with no live result
Suppose a base number returns nothing from either the OEM or a distributor.
- Check supersession first: a null result usually means the number is superseded, not that the part is gone. Trace the successor before concluding it is obsolete.
- If genuinely retired: classify the part as obsolete and move to a mitigation route (last-time buy, qualified second-source or upgrade) rather than continuing to search a dead number.
Common pitfalls when reading OEM part numbers
- Dropping the revision suffix. Searching the base is correct; discarding the revision from your records is not. You need the suffix to confirm what is fitted.
- Treating a label number as the order number. A number stencilled on a casting may be a sub-component or drawing number, not the orderable assembly. Confirm the orderable level before quoting.
- Assuming higher revision equals compatible. Revision increments can be fit-affecting. Verify interchangeability, do not infer it.
- Confusing revision with supersession. A new suffix on the same base is a revision; a different base number is a supersession. The two demand different checks.
Frequently asked questions
How do I look up a LAM or TEL part number?
Capture the full number including its revision suffix, split it on the hyphens to identify the prefix, base number and revision, then search the base number against a qualified parts catalogue or an obsolescence-aware distributor. Finally, confirm the number has not been superseded by a later part before ordering.
What does the part number prefix mean?
The prefix is the leading hyphen-separated group and indicates the part class or commodity grouping, for example distinguishing a machined assembly from an electronic or consumable item. It is used to classify and route a request; the middle base number, not the prefix, is what you search and cross-reference on.
What is the difference between a revision and a supersession?
A revision keeps the same base number and changes only the trailing suffix to record an engineering iteration. A supersession retires the whole number and replaces it with a different one. A revision is checked for interchangeability; a supersession is traced to its successor at the end of the chain.
Can I order a higher revision as a replacement?
Not automatically. A higher revision suffix usually indicates a later iteration, but some revisions are fit-affecting and are not backward-compatible. Confirm interchangeability against the OEM change note or a qualified supplier’s equivalence statement before fitting a different revision to a running tool.
What is a part number cross-reference?
A cross-reference is a one-to-one mapping from an OEM part number to a qualified second-source SKU that is equivalent in form, fit and function. It lets a fab buy a qualified equivalent, consolidate its supply chain and reduce dependence on a single OEM source without compromising on part quality.
What if a part number returns no results?
A null result most often means the number has been superseded rather than that the part no longer exists, so trace the successor first. If the number is genuinely retired with no OEM replacement, treat it as an obsolescence trigger and move to a last-time buy, a qualified second-source, or an upgrade.
Decode the number, then qualify the part
Reading a LAM or TEL part number correctly turns a string of digits into an actionable identity: a class, a stable base and a revision you can verify. From there, ESCT can help you cross-reference that base to a qualified second-source equivalent, trace any supersession and keep your legacy 200mm tools supplied. If you are working through an awkward number or building a cross-reference table for a fleet, our parts and obsolescence support team can help you confirm form, fit, function and qualification before you commit to an order.
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