PCB fabrication: preserve the story inside the bare board.

PCB fabrication produces the board structure and its electrical connections. Printed circuit board assembly (PCBA) adds components and their connections to that board. A fabricated board can therefore pass its agreed checks while still requiring assembly inspection, programming and functional testing before it becomes part of usable equipment.

Define the handover between the fabricator and assembler. Agree the board revision, supplied quantity, identification method, packaging requirements and acceptance evidence. Establish how questions return to the design owner. A purchase order and a drawing with similar names are insufficient when one contains an unapproved change or a different layer arrangement.

A stackup describes the arrangement of conductive and insulating layers through the board. Review it with the fabrication drawing, material specification, copper requirements, finished thickness and any controlled electrical characteristics. Record which requirements are essential to the design and which choices the fabricator is authorised to make.

Keep engineering questions and their approved answers with the released data package. If a material becomes unavailable, a proposed replacement should return through the agreed evaluation process. Similar catalogue descriptions do not establish equivalence for a particular product. Preserve the approved construction actually used, so a later investigation does not depend on the latest revision alone.

Eurocircuits describes checks of drilled-hole position against inner layers, followed by hole-wall preparation and copper-plating checks. These steps connect geometric alignment with the conductive path through the board; they need to be interpreted together.

Retain panel identities, programme revisions, process exceptions and inspection results. Check how restarts and reprocessed panels enter the record. Compare observations with the approved board requirements rather than borrowing dimensions or process settings from a different product.

Eurocircuits describes microsectioning as destructive examination of a sample, used to inspect features such as multilayer structure, hole plating and conductor registration. Registration is the alignment of features relative to one another. A section can reveal information that a finished-board photograph cannot show.

Connect each examined coupon or board to its production context and the agreed sampling plan. Preserve the location, preparation, measurements and reviewer decision. A useful result identifies what was examined and which population it represents. Avoid presenting one acceptable cross-section as direct inspection of every internal feature on every supplied board.

Eurocircuits describes bare-board electrical testing against a reference netlist for shorts and open circuits. The netlist expresses the intended electrical connections. Its revision and origin therefore belong beside the test result.

Keep that result distinct from checks of board dimensions, soldermask alignment and the specified surface finish. Soldermask covers selected areas; the finish protects designated exposed metal for its intended use. Review the complete acceptance package rather than allowing one pass flag to stand for all required checks. Record unresolved discrepancies before the boards move into assembly.

Hypothetical example: an assembled controller develops an intermittent connection near a plated hole. The team locates the board lot, fabrication revision, relevant sample results and subsequent assembly history. It keeps the returned unit intact until the responsible specialists agree an examination plan, rather than immediately assigning the failure to the fabricator or assembler.

Start with a narrow question and preserve competing explanations. Compare affected and unaffected material using documented identities, then assign the next examination and the product-disposition decision. Record what the evidence rules out and what remains uncertain. VIEOX welcomes a discussion about the information needed to make this handover and investigation easier to follow.