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Standards and what they prove

Naming a standard is cheap. This page says, for each one, what it actually governs, who holds the evidence — us or the plant — and where to find it. Where we work to something without being certified for it, that is stated just as plainly.

Standards 19
Acceptance IPC-A-600
Classes 2 or 3
Evidence on request

Who holds the evidence

[ How to read this ]

We are an engineering office, not a plant. That distinction decides who holds the certificate for almost every standard here — and it comes up in an audit anyway. So it sits at the front rather than in the small print.

Ours
The evidence is held by LEXINGTON and issued by us.
Plant level
The certification belongs to the manufacturing plant. We select against it, audit against it and pass the valid certificate on.
On request
The document exists and is current. Whether it sits with us or with the plant, we tell you when we send it.
Applied
We work to the standard but hold no certificate of our own for it. Where that is the case we say so rather than stretch the wording.
Specified
A design, test or data standard. There is nothing to certify here — it is specified and complied with.

Management and process

[ System ]

The system standards. They say nothing about an individual board — only about whether the operation building it works reproducibly.

ISO 9001

On request

Quality management system. The base evidence that processes are documented, controlled and auditable.

Valid certificates sit in the download centre and need no enquiry.

Proven under Download centre →

IATF 16949

Applied

Quality management for the automotive industry. Requires process capability evidence, sampling and structured problem handling.

We work to IATF-16949-oriented processes — CpK monitoring, PPAP at the level required, 8D reports. That is deliberately not phrased as a certification of our own.

Proven under Quality →

ISO 13485

Plant level

Quality management for medical devices. Tightens traceability, change control and record retention.

Carried as a plant certification. For medical projects we select the plant on it and fix the traceability in the order.

Proven under Medical technology →

ISO 14001

Plant level

Environmental management system. Governs how an operation records, controls and evidences its environmental impact.

A selection criterion in plant assessment where the application demands it — not carried as a certificate of our own.

Proven under Sustainability →

Product and acceptance

[ Acceptance ]

The standards a delivered board is measured against. If a complaint is to be a measurement rather than an opinion, this is where the yardstick sits.

IPC-A-600

Specified

Acceptance criteria for the finished board — what is visibly permissible on the delivered part. Class 2 as standard, Class 3 for elevated reliability.

Fixed in the order rather than left to the plant standard. Which class makes sense when is covered further down.

Proven under Delivery specification →

IPC-6012

Specified

Performance requirements for rigid boards. The counterpart to IPC-A-600: not the visible appearance but the qualification required.

Specified together with the acceptance class. Its classes run parallel to IPC-A-600.

Proven under Delivery specification →

IPC-SM-840

Specified

Qualification of the solder mask — adhesion, insulation, resistance to soldering and cleaning processes.

Class T as standard, minimum dam ≥ 100 µm.

Proven under Solder mask →

IPC-4101

Specified

Base material specification. The slash sheet after the number identifies the material unambiguously — /21 is standard FR-4.

Laminate and prepreg are named in the order and are not interchangeable without a written agreement.

Proven under FR-4 →

IPC-4761

Specified

The seven types of via protection — tenting, plugging, filling, filled and capped. Four of them matter in practice.

The type belongs in the fabrication notes. Closing from one side only produces voids and is the most common query point.

Proven under Via plugging →

Design, test and data

[ Specified ]

Standards that bite before manufacturing. There is nothing to certify here — they decide whether your data is unambiguous and whether a measured number is comparable.

IPC-2221 / 2222

Specified

Generic design standard for printed boards: clearances, aspect ratios, layer build-up, dielectric withstand.

The basis of our design guidelines. Where we are stricter than the standard, the reason is given with it.

Proven under Design guide →

IPC-2152

Specified

Current carrying capacity of conductors as a function of width, copper thickness, permissible temperature rise and position in the stack.

The reference for heavy copper sizing. Inner layers carry considerably less current than outer layers of the same width.

Proven under Heavy copper →

IPC-2581

Specified

Data exchange format carrying layer order, netlist and fabrication notes in a single file — rather than spread across Gerber plus a separate sheet.

Preferred over Gerber, on a par with ODB++. Both remove a whole class of ambiguity.

Proven under Data formats →

IPC-TM-650

Specified

The test methods manual. Defines how a value is measured — Tg by DSC to method 2.4.25, for instance.

The reason two datasheets quoting the same Tg are comparable. Without the method, the number alone is worth little.

Proven under Material values →

Material, environment and conformity

[ Conformity ]

What hangs on material and delivery. These are usually requested not by engineering but by purchasing, regulatory approval, or a customer further up the chain.

RoHS

Ours

Restriction of hazardous substances in electrical and electronic equipment.

Compliant material selection as standard, with a declaration of conformity per delivery.

Proven under Compliance →

REACH

Ours

European chemicals regulation, including the duty to disclose substances of very high concern.

Declaration of conformity per delivery. PFAS status is documented as the regulation develops.

Proven under Compliance →

IMDS

Ours

The automotive industry material data system. It expects the build as actually made, not a generic entry.

We create the datasets ourselves, for the build as manufactured.

Proven under IMDS datasets →

UL 94 / UL 796

Plant level

Flammability class of the base material (94 V-0) and listing of the board as a component (796).

Listing depends on plant and material combination. Where a UL mark is required on the board, it belongs in the fabrication notes.

Proven under Specification →

EN 45545-2

Plant level

Fire protection in railway vehicles. Requires evidenced fire and smoke behaviour of the materials used.

A material property, not a process certification. Halogen-free builds are the usual route — the material certificate comes from the laminate manufacturer.

Proven under Halogen-free PCBs →

IEC 61249-2-21

Specified

Defines "halogen-free" as a limit rather than a marketing claim — chlorine and bromine each below 900 ppm, the sum below 1500 ppm.

Without this standard, "halogen-free" on a datasheet cannot be checked.

Proven under Halogen-free PCBs →

Class 2 or Class 3

[ Decision ]

The one entry that affects every enquiry and is missing most often. The class changes acceptance criteria, inspection scope and price — not the manufacturing technology. Putting Class 3 on an assembly that does not need it does not buy a better board; it buys tighter inspection and a lower yield.

Criterion Class 2 Class 3
Intended for Equipment with an expected service life where a failure is an annoyance Assemblies where a failure is not acceptable
Typically Industrial, consumer, most automotive applications Medical, aerospace, safety-related controls
Barrel copper Class minimum Higher minimum, evidenced by micro-section
Annular ring Reduced rings permitted Defined minimum ring, breakout not permitted
Repairs Permitted within limits Severely restricted to excluded
Documentation Inspection record Micro-section report and full traceability
Effect Standard price and lead time Lower yield, higher price, longer inspection

If you are unsure: Class 2 with our delivery specification on top sits closer to Class 3 than a bare Class 2 does on the points that actually drive failures — without the yield loss across the whole board. Ask us about your specific case.

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