IPC class 2 vs class 3
IPC class 2 and class 3 are two acceptance levels defined in IPC standards (A-600 for bare boards, A-610 for assemblies). Class 2 covers dedicated-service electronics; class 3 covers high-reliability electronics where failure cannot be tolerated. Class 3 demands tighter tolerances, stricter inspection, and typically costs more.
What it is
IPC defines three classes of electronic products. Class 1 covers general consumer electronics where the product is expected to function but extended life is not required. Class 2 covers dedicated-service electronics such as industrial equipment, telecommunications, and most professional gear — products that need continuous performance but where occasional failure is acceptable. Class 3 covers high-performance, high-reliability electronics: medical devices, avionics, military systems, and life-support equipment where failure could endanger people or mission outcomes.
The class affects almost every aspect of fabrication and inspection: annular ring minimums, allowable hole wall voids, solder mask registration, copper plating thickness, and the threshold for what counts as an acceptable defect. Class 3 typically requires 100% electrical test, tighter dimensional tolerances, and more rigorous documentation.
The class is set on the order, not on the design — the same Gerber package can be built to class 2 or class 3, with the higher class costing more and taking longer.
When it matters
Choosing the right class affects cost, lead time, and risk in opposite directions. Class 2 is the default for most commercial hardware and is sufficient for industrial, consumer, and prototype work. Class 3 is required by customer specification in regulated industries (medical, aerospace, automotive ECUs) and typically adds 15-35% to assembly cost and 2-5 days to lead time, driven by 100% inspection, mandatory X-ray on BGA joints, and stricter solder and plating acceptance criteria. Specifying class 3 when class 2 is sufficient wastes money; specifying class 2 when class 3 is required can disqualify the board from its intended application.
Comparison
Exact dimensional and plating thresholds are defined in IPC-A-600M and IPC-6012F. Refer to current revisions for specific values.
At Nordic PCB
Class 2 is our default. We supply class 3 on request, and our certified suppliers are audited for class 3 production. State the required class in your RFQ and we include the corresponding inspection level and certificate of conformance in the quote — no need to ask separately.
Related terms
- IPC-A-600
IPC-A-600 is the IPC standard that defines visual acceptance criteria for bare printed circuit boards. It specifies what surface, dimensional, and structural conditions are acceptable across three class levels, and is the reference document fabricators use to inspect boards before shipment.
- IPC-A-610
IPC-A-610 is the most widely used acceptance standard for assembled PCBs, defining visual criteria for solder joints, component placement, cleanliness, and damage across three class levels. The current revision is IPC-A-610J (March 2024). It is the companion standard to IPC-A-600 for bare boards.
- DFM
DFM (Design for Manufacturability) is a structured review of your PCB design against a fabricator's process limits — trace widths, drill sizes, annular rings, solder mask clearances, and stack-up choices — to catch issues before tooling starts. A good DFM review prevents rework, scrap, and missed delivery dates.
- Annular ring
An annular ring is the copper surrounding a drilled hole on a PCB pad, measured from the edge of the finished hole to the outer edge of the pad. IPC-6012 sets minimum annular ring sizes: Class 3 requires at least 2 mil (0.05 mm) on external layers and 1 mil (0.025 mm) on internal layers.