Back to News & Events A procurement and engineering reference for semiconductor equipment OEMs, published by Horizon PSS.
Power supplies rarely appear on a semiconductor tool’s critical path until they put themselves there. A metrology platform six weeks from customer acceptance starts showing noise artifacts traced to a catalog supply. A deposition tool trips during fab qualification because nobody verified voltage-sag ride-through. An OEM discovers that the supply designed into a ten-year platform has been discontinued in year three, with no PCN and no qualified replacement.
Each of these failures was purchased, not designed. They happen at the point where an OEM’s engineering requirements meet a procurement process built for commodity components. This guide explains why semiconductor equipment power resists catalog selection, when custom and semi-custom development is the correct answer, and how an OEM procurement team should structure the RFQ and evaluate the NRE proposal when it is.
The Compound Requirement Problem in OEM Power Specifications
No single specification makes semiconductor equipment power difficult. The difficulty is the intersection.
A metrology or inspection tool may need sub-millivolt ripple on detector rails, because noise on those rails appears directly in the measurement. A fab will require SEMI F47 voltage-sag ride-through, because a tool trip scraps wafers in process. Cleanroom installation may prohibit fans, because moving parts shed particles, which forces conduction or convection cooling and reshapes the entire thermal design. And the platform will sell for a decade or more, so the OEM needs supply continuity, configuration control, and change notification for the life of the program.
Catalog units exist for each OEM requirement individually. Low-noise supplies exist. F47-compliant supplies exist. Fanless supplies exist. The combination, at your power level, in your envelope, with your rail structure, almost never does. OEM engineering teams typically discover this late, after the architecture has hardened around an assumed off-the-shelf solution, which is precisely when the discovery is most expensive.
The practical rule: audit the compound requirement before the architecture freezes. If more than two of the constraints above apply simultaneously, scope the NRE for the custom and semi-custom paths early, and structure the RFQ around the compound requirement while changing course is still cheap.
Catalog, Semi-Custom, or Custom: Which Path an OEM RFQ Should Take
Catalog. Correct when a standard unit genuinely meets every OEM requirement with margin, the volumes do not justify NRE, and the OEM accepts the manufacturer’s lifecycle terms as published. Catalog is also the right prototype vehicle: proving a subsystem with a standard unit and deferring the sourcing decision until requirements stabilize is good engineering. The risk is silent obsolescence. A catalog part carries no program commitment, and the OEM holds the redesign risk when it changes or disappears.
Semi-custom. The most underused path in the industry, and for most semiconductor OEM programs the correct one. A proven platform is adapted: modified output rails, custom EMI filtering, mechanical repackaging for the tool envelope, firmware and telemetry changes, extended qualification including F47 verification in the OEM’s configuration. NRE is a fraction of a ground-up development because the topology, safety approvals, and manufacturing process already exist. Schedule is typically months rather than a year or more, and the RFQ can reference the parent platform’s existing approvals. The OEM gains what catalog cannot provide: a controlled configuration, program-level change notification, and a supplier with design authority over the exact unit being shipped.
Full custom. Justified when the requirement is architecturally unreachable from any platform: unusual rail counts, extreme noise budgets, vacuum-adjacent packaging, envelope constraints that dictate the topology. Full custom carries the highest NRE and the longest schedule, and it buys the most: a power system designed around the tool rather than a tool designed around available power. For flagship platforms with long production lives, the NRE amortizes to insignificance per unit.
An honest supplier will tell an OEM which path the requirement actually needs. A supplier who quotes full custom for a semi-custom problem is selling engineering hours. A supplier who forces a catalog unit into a compound requirement is selling the OEM a qualification failure on layaway.
What SEMI F47 Actually Demands, and What “Compliant” Must Mean in Your RFQ
SEMI F47 specifies the voltage sags a semiconductor tool must ride through without interrupting the process: defined depth-and-duration points, such as continued operation through a sag to 50% of nominal voltage for 200 milliseconds. Fabs enforce it at tool acceptance because grid sags are routine events and an interrupted process means scrapped wafers and requalification time.
For the power subsystem, F47 is primarily a hold-up and input-stage design problem, and it interacts with everything else. Hold-up energy costs capacitance; capacitance costs volume; volume fights the envelope; and in a fanless design the added components fight the thermal budget too. This is why F47 belongs in the OEM’s RFQ from the first draft, not in a late revision, and why the NRE proposal should price the ride-through verification explicitly. Retrofitting ride-through into a finished design is one of the most expensive changes in power engineering.
OEM procurement teams should also be precise about the word “compliant.” Designed to F47 means the engineering intent existed. Verified to F47 means the unit was tested against the sag profile, in a configuration matching what ships, and a report exists. Fab acceptance engineers ask for the report. The OEM’s RFQ should ask for it too, and should state that qualification evidence in the delivered configuration is a contractual deliverable, not a datasheet claim.
How OEM Power Procurement Should Run: From RFI to RFQ to NRE to PCN
Custom and semi-custom power follows a different procurement rhythm than commodity buying. OEM teams that know the stages, and what to demand at each one, systematically get better outcomes.
RFI and feasibility. Send requirements at whatever maturity they exist. A competent supplier returns a feasibility assessment, the open questions, and a recommendation among catalog, semi-custom, and custom, with reasoning. A supplier who answers an RFI with nothing but unit pricing has skipped the engineering.
The NRE proposal. This document is where programs are won or lost, and it deserves the same scrutiny as the hardware. A good NRE proposal itemizes: design deliverables and review gates, a qualification test plan with methods and acceptance criteria (F47 profile, ripple measurement bandwidth, EMC standards and levels, thermal conditions), the documentation package, unit pricing structure at program volumes, and a schedule with named milestones. Red flags: NRE quoted as a single number with no deliverable list, qualification described as “per applicable standards” without naming them, and no stated position on who owns the design data.
Design reviews. The OEM’s engineers should see the architecture, the derating analysis, and the compliance strategy at preliminary and critical design review, while changes cost paper rather than tooling. Treat supplier resistance to design reviews as disqualifying.
Qualification. Testing runs to the plan agreed in the NRE proposal and produces reports the OEM can hand directly to a fab acceptance team or a certification body. Deviations are documented and dispositioned jointly, not discovered downstream.
Production and lifecycle. This is where catalog and program sourcing diverge permanently. The RFQ should require configuration control (the qualified unit and the production unit are identical, enforced by process), PCN discipline (advance notification of any change affecting form, fit, function, or compliance), proactive obsolescence management with qualified replacements, and a stated production-availability commitment matched to the platform’s expected life. For a semiconductor tool platform, ten years is a reasonable ask in the RFQ. A supplier unwilling to put lifecycle terms in writing is quoting a transaction, not a program.
What an OEM Should Put in the RFQ
The RFQs that get accurate quotes and short clarification cycles contain: input voltage, phase, and frequency, with F47 stated explicitly if required; every output rail with voltage, continuous and peak current, regulation, and ripple limits referenced to a measurement bandwidth; environment, including ambient range, cooling available, cleanroom class or vacuum adjacency; mechanical envelope, mounting, and connector constraints; the complete standards list, including customer-specific fab requirements; monitoring and control interfaces; and the program data — prototype quantities, ramp profile, annual volume, and expected production lifetime.
An incomplete RFQ is acceptable. A vague one is not. “Low noise” is not a specification; “≤1 mV p-p, 20 MHz bandwidth, on rails 3 and 4” is. The quality of the NRE proposal an OEM receives is bounded by the quality of the RFQ it sends.
FAQ: OEM Procurement of Custom and Semi-Custom Power
What does NRE typically cost, and what should it include? NRE scales with how far the requirement sits from an existing platform: semi-custom adaptation typically runs a fraction of a ground-up development, while full custom for a compound requirement can reach the cost of a small engineering program. The number matters less than the itemization. A quotable NRE proposal lists design deliverables, review gates, a named qualification plan with acceptance criteria, and the documentation package. If the RFQ response gives one figure with no deliverable list, the OEM is buying hours, not outcomes.
How long does it take from RFQ to qualified production units? Semi-custom programs typically run a few months from NRE approval to qualified first articles, because topology, safety approvals, and manufacturing already exist. Full custom development generally runs twelve months or more, driven by design iterations and qualification depth, with F47, EMC, and environmental testing on the critical path. The schedule an OEM should trust is the one in the NRE proposal with named milestones and review gates, not a lead time quoted verbally at RFI stage.
Who owns the design after the OEM pays the NRE? It varies by supplier and must be settled in the NRE contract, not assumed. Common models: the supplier retains design ownership and grants the OEM exclusivity for the configuration; or the OEM buys the design data outright, usually at higher NRE. What the OEM must secure in writing regardless: access to the documentation needed for fab acceptance and certification, exclusivity terms if the design encodes competitive advantage, and escrow or transfer rights if the supplier exits the business. Ambiguity here surfaces at the worst possible time, mid-program.
What happens when a component inside the supply goes end-of-life mid-program? Under a program agreement, obsolescence is the supplier’s problem to manage and the OEM’s problem to verify. The supplier monitors component lifecycles, executes last-time buys or qualifies replacements, and issues a PCN before any change affecting form, fit, function, or compliance reaches production. The OEM’s RFQ should make PCN discipline and a production-availability commitment contractual, with a notification period long enough to requalify if needed. With a catalog purchase, none of this exists: the OEM finds out when the distributor shows zero stock.
How Horizon PSS Structures These Programs
Horizon PSS develops custom and semi-custom power supplies for semiconductor equipment as defined OEM programs rather than transactions. Every engagement begins with a feasibility review and an honest path recommendation, including catalog when catalog is genuinely sufficient. NRE proposals itemize deliverables, review gates, and a named qualification plan, with SEMI F47 verification, ripple data referenced to measurement bandwidth, and EMC evidence delivered as part of the package. Configuration control, PCN discipline, and obsolescence management run for the life of the program, because a semiconductor platform’s power source has to be planned on the platform’s horizon, not the component market’s.
If your tool’s requirements have outgrown the catalog, send the specification at whatever maturity it exists, or a full RFQ if you have one. NRE scope, deliverables, and schedule come back in writing. Our engineering team will return a feasibility assessment and the fastest compliant path to production.
