Industries · Energy, power & grid
Assembly for solar inverter, storage BMS and PCS, DC-DC, charging module, smart meter and protection relay boards. A 20 mil trace carries about 3.2 A at 2 oz, 5.5 A at 4 oz and 7.8 A at 6 oz, and 6 oz can more than double board cost — so copper weight is a design decision we quote against, not a default. Voiding is accepted to IPC-7095, coating to IPC-CC-830, laminate specified as UL 94V-0 on power boards. Heavy-copper bare boards are sourced from audited partner fabs, with incoming inspection and full lot traceability. Where a cabinet needs a UL 508A listing, that listing is held by the panel builder and we assemble and document to it. Assembly lead time ex-components.
Copper, clearance, voiding
Power design conversations start with current, not with placement accuracy. This table is the technical vocabulary the vertical actually uses — and it separates the bare-board parameters from the assembly-side ones, because they belong to different suppliers.
| Parameter | Values | Whose scope |
|---|---|---|
| Current capacity20 mil trace, still air | About 3.2 A at 2 oz, 5.5 A at 4 oz and 7.8 A at 6 oz. Copper weight is selected against the current and thermal design before the stack-up is fixed. | Joint decision — we quote against the copper weight your design and thermal budget require |
| Cost effect | 6 oz can more than double board cost against a 2 oz equivalent, before the wider trace and space rules are counted. | Design and sourcing decision, quoted transparently before tooling |
| Flame retardance | UL 94V-0 flame-retardant laminate specified on power assemblies. | Bare-board fab — confirmed at incoming inspection on the laminate documentation |
| Creepage and clearance | Spacing is set from the working voltage and the pollution degree, and is confirmed together with your stack-up during design review rather than assumed from a table. | Bare-board fab for the pattern, assembly-side for coating coverage of the gaps |
| Board thickness | Assembly envelope 0.4–4.0 mm. Power boards with heavy copper usually sit in the upper part of that range. | Assembly-side envelope — boards outside it are flagged at DFM stage |
| Void acceptance | IPC-7095: Class 2 at single voids up to 25% of pad area and total voiding up to 40%; Class 3 at 10% and 25%. Inspection scope and X-ray coverage are configured per project. | Assembly-side — we own the solder acceptance criteria |
Field life and certification friction
A grid-connected converter is specified against a warranty measured in decades while its control electronics are replaced far sooner. That gap is the reason this vertical pays for coating integrity, void control and long-life supply planning.
On power stages, voiding under a thermal pad raises junction temperature and shortens the life of the device beneath it. IPC-7095 gives the acceptance language — Class 2 at 25% single-void and 40% total, Class 3 at 10% and 25% — and the profile, paste and pad geometry have to be developed toward that limit rather than inspected for it afterwards.
UL 9540A Edition 6 costs between USD 505 and USD 1,258 for the documentation alone, before any physical testing is booked. Changing a board without re-testing can put an existing UL 1741 listing at risk, so every BOM change runs through the OEM's change-control approval instead of through procurement.
The median field life of a string inverter is reported at 10–13 years against a 25-year module warranty. That figure is vendor-published and is an industry illustration rather than a specification; its consequence is real, though, because each replacement is a truck roll, a possible interconnection amendment and a warranty argument.
Conformal coating is what keeps humidity, condensation and conductive dust off a high-voltage assembly. Coating defects do not fail at end-of-line test; they fail in the field, which is why coating is qualified to IPC-CC-830 and inspected under UV fluorescence so voids in coverage are visible before the board ships.
Field equipment is maintained, not replaced. When a gate driver or a sense resistor goes end-of-life while installations are still under warranty, the operator needs a supported replacement path — which means lifetime buys and qualified second sources have to be planned while the part is still orderable, not after the last-time-buy window closes.
A defect that reaches distributed generation is remedied across an installed base that may span thousands of sites and several countries. That is why this vertical asks for lot-level traceability from the first sample order, so a suspect production window can be bounded without de-energising assets that were never affected.
Record
A Dutch grid-equipment manufacturer had a two-layer power board in series production when a critical component was discontinued, with installations still under committed service life. A redesign was unattractive because the board sat inside a certified assembly. We ran a BOM risk scan across lifecycle status, single sourcing, lead time and counterfeit exposure, identified and qualified a second source with datasheet parameter comparison and the customer's written approval, and placed a last-time-buy covering the remaining production forecast plus attrition — timed inside the J-STD-048 window rather than after it.
Assembly side
On a power assembly our scope is the solder joint, the coating and the electrical test. Copper weight, stack-up, laminate and creepage geometry are fixed by the bare-board fab we source from — a distinction energy buyers test for early, because the follow-up question is always where the lamination line is.
Through-hole power joints are filled by robotic selective soldering with a single nozzle and a programmed path per joint, which replaces hand touch-up on high-current connections and avoids reheating nearby surface-mount devices. Void acceptance follows IPC-7095, with X-ray coverage configured per project rather than applied to every board.
Coating is applied to IPC-CC-830 chemistry families — acrylic, silicone or polyurethane — and inspected under UV fluorescence so thin or missing coverage is visible on the line. Ionic contamination is verified by ROSE testing to IPC-TM-650 where the programme requires it, and coating and sensitive final assembly run in an ISO Class 8 clean area.
Electrical safety testing includes Hi-Pot dielectric withstand on the assemblies that require it. Power-conversion assemblies reference IPC 9592B practice, board thickness spans 0.4–4.0 mm, and every shipment carries lot-level traceability covering the bare-board lot, component lots and process records.
Long-life supply
None of these guarantees that a part will still be manufactured in 2040. They guarantee that the decision points are identified early enough for you to act on them.
Lifecycle status, single-source lines, long lead time and counterfeit exposure are screened on every BOM before tooling, following AS5553 and AS6081 anti-counterfeit practice for purchased parts. The result is a risk list you can act on while alternatives still exist on the market.
Output: risk list delivered before tooling is released
We never substitute automatically. An alternate is compared against the original datasheet on electrical parameters, temperature grade and package, with approved-vendor-list parts preferred, and the change is implemented only after your written confirmation — which is what keeps the assembly inside your existing certification.
Rule: no automatic substitution on any power assembly
Component change and discontinuation notices are tracked on the J-STD-046 pattern, and last-time-buy quantities are derived from your remaining forecast plus attrition inside the J-STD-048 window of 12 months for the last order and six months for final delivery. Reserved stock is held against your part number.
Timing basis: J-STD-048 12-month order window
Next step
Send the design with the working voltage, the continuous current on each power net and the intended certification path. We will confirm the copper weight the design implies, the void criteria we can hold on the joints, and which parts of the assembly sit with the bare-board fab rather than with us. Assembly lead time ex-components; long-lead semiconductors can add 12–26 weeks.
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Power boards carry heavier, costlier parts, so minimums are agreed per design. As a guide, 0603–2225, SOT, SOD and MELF packages start at 50 pcs plus 30 spares; larger packages at 100 pcs plus 50 spares.
Related reading: all six industry pages, industrial automation, and quality and inspection scope.