| Applicable PCB Class | Product environment and consequence of failure | Select IPC Class 2 for general industrial products and Class 3 when continuous high reliability or uninterrupted operation is required. Confirm the class on the drawing and purchase specification. | Approved drawing, purchase specification, and supplier quality agreement referencing IPC acceptability requirements | Critical |
| Base Material | Laminate type, Tg, Td, CTE, and moisture sensitivity | Use a material system suitable for the operating temperature and signal speed. For many industrial designs, a Tg of approximately 130°C or higher is a practical starting point; high-temperature designs require engineering confirmation. | Material certificate, controlled laminate datasheet, lot traceability, and approved material list | Critical |
| Copper Thickness | Finished copper thickness on outer and inner layers | Specify finished copper, not only starting foil. Common nominal values are 18 µm, 35 µm, and 70 µm; use the calculated current-carrying and thermal requirements to determine the final value. | Microsection report, coating-thickness measurement, and electrical resistance test | High |
| Dimensional Accuracy | Board outline, hole location, slot position, and layer registration | Use drawing-specific tolerances. Typical prototype and production values may be around ±0.10–0.20 mm for board dimensions, but connector, press-fit, and mechanical features require tighter approved tolerances. | Coordinate-measuring report, tooling inspection, first-article inspection, and panel drawing approval | High |
| Hole and Via Quality | Plated-through-hole continuity, annular ring, drill wander, and wall integrity | No open or short circuits; annular ring, hole size, plating thickness, and aspect ratio must meet the approved design and applicable IPC-6012 requirements. | 100% electrical test, microsections, automated optical inspection, and drill-registration records | Critical |
| Solderability and Finish | Surface-finish type, thickness, oxidation resistance, and solder wetting | Choose the finish according to storage life, assembly process, contact requirements, and cost. Finish thickness and solderability must comply with the approved specification; avoid exposed copper, contamination, and excessive surface oxidation. | Finish certificate, ionic cleanliness data, solderability test, and visual inspection under controlled lighting | High |
| Electrical Integrity | Net continuity, isolation, impedance, and dielectric withstand | Require 100% netlist testing for production lots. Controlled-impedance traces should normally be verified within the design tolerance, such as ±10%, unless the signal specification requires a tighter limit. | Flying-probe or fixture test, impedance coupon report, dielectric-withstand record, and approved test program | Critical |
| Assembly Quality | Component placement, solder joints, cleanliness, and process control | For assembled boards, define IPC-A-610 and J-STD-001 acceptance criteria, with documented controls for solder paste, reflow profile, voiding, rework, and electrostatic discharge protection. | AOI, X-ray where applicable, reflow profile, solder-joint inspection, process capability data, and ESD audit records | Critical |
| Thermal Reliability | Operating temperature, thermal cycling, and copper-to-laminate durability | Set the temperature range from the real application. Qualification cycles, dwell time, ramp rate, and sample size should be defined by the product reliability plan rather than copied as a universal value. | Thermal-cycling report, post-test microsections, electrical retest, and failure-analysis records | Critical |
| Environmental Reliability | Humidity, corrosion, vibration, shock, and contamination exposure | Define tests according to the installation environment. Industrial products may require humidity-bias, salt-mist, vibration, or shock testing when exposed to condensation, chemicals, transport loads, or moving equipment. | Environmental qualification plan, chamber logs, vibration or shock report, and visual/electrical post-test inspection | High |
| Flammability | Insulation system flammability and enclosure safety requirements | Specify the required flammability rating, such as UL 94 V-0, only when required by the end-product safety assessment. The rating must apply to the relevant material system and thickness. | Material flammability documentation, safety evaluation, and controlled material traceability | High |
| Manufacturing Management | Quality system, change control, corrective action, and traceability | Prefer an independently audited ISO 9001 quality management system. Require lot, material, process, operator, equipment, and test traceability for safety- or reliability-critical products. | Valid certificate, audit report, process flow, control plan, nonconformance records, and change-notification procedure | Critical |
| Restricted Substances | Material composition and restricted-substance declarations | Require compliance with applicable RoHS substance limits under Directive 2011/65/EU and amendment (EU) 2015/863, plus REACH obligations where the product is placed on the relevant market. | Supplier declaration, homogeneous-material data, and laboratory test results based on IEC 62321 methods when required | Critical |
| Cleanliness and Corrosion Control | Ionic contamination, residues, exposed copper, and surface corrosion | Set an ionic-cleanliness limit in the assembly specification and maintain a no-residue requirement where leakage or electrochemical migration could affect reliability. The limit must reflect the flux chemistry and product environment. | Ion chromatography or ROSE screening where appropriate, visual inspection, and process-cleanliness trend data | High |
| Inspection Coverage | Defect detection at bare-board and assembled-board stages | Use AOI for pattern and placement defects, electrical testing for net integrity, X-ray for hidden solder joints when applicable, and microsectioning for process qualification and periodic verification. | Inspection plan, test coverage report, equipment calibration records, and defect escape analysis | High |
| Documentation and Change Control | Revision control, deviations, process changes, and records retention | Require controlled Gerber or ODB++ data, drill files, stack-up, impedance requirements, approved deviations, and prior notification for material, process, tooling, or site changes. | Document register, revision history, engineering-change notice, certificate of conformance, and retained production records | Critical |
