A manufacturing specification should describe the complete construction—not a list of isolated minimum dimensions.

This page is a requirements and review guide. Numerical production limits, material stock and certifications must be confirmed for the actual supplier and design; they are not advertised here without evidence.

The fabrication specification matrix

Parameter	What to specify	Why it matters
Layer construction	Eight copper layers, layer map, material grade, PP/core schedule	Defines lamination and electrical geometry.
Finished thickness	Nominal, tolerance, mask inclusion, connector constraints	A nominal 1.6 mm callout alone may not settle mechanical fit.
Copper	Starting and finished copper by layer; plated outer requirement	Copper affects etch geometry, resin demand and hole plating.
Trace / spacing	Smallest actual geometry, location and final copper requirement	A process minimum depends on copper thickness and feature type.
Holes / vias	Finished diameter, plating, layer span, tolerance and fill/cap requirements	Aspect ratio and via technology must be assessed together.
Impedance	Target, tolerance, net class, layer, reference and test method	Allows supplier geometry review and meaningful test evidence.
Surface finish	Finish type, contact requirements, assembly cycles, storage	Flatness and handling constraints can change the preferred finish.
Acceptance	Applicable standard/revision/class, sampling and required reports	Avoids assuming an inspection level from the application name.

Choose the via process before tightening the layout

Architecture	What it changes	Review before release
Plated through-hole	One barrel crosses the entire finished board	Finished hole and drill tool, aspect ratio, annular rings and unused stubs.
Blind / buried vias	Selected layer spans can require extra manufacturing stages	Approved spans, lamination sequence, registration and access for inspection.
Laser microvias	Small buildup connections depend on dielectric and target geometry	Stacked versus staggered construction and qualification evidence.
Via-in-pad filled and capped	Adds filling, planarization and capping requirements	Fill type, void acceptance and assembly pad flatness.
Backdrilling	Removes an unused portion of a plated barrel	Depth tolerance, remaining stub, keepouts and inspection method.

Surface finish: match the assembly and contact function

Finish	Useful decision factors	Questions to resolve
ENIG	Flat solderable surface for fine-pitch assembly	Finish thickness specification, process control and solder joint requirements.
Lead-free HASL	Solder coating and process familiarity	Pad flatness, fine-pitch compatibility and thermal exposure.
OSP	Organic copper protection	Handling, storage, assembly sequence and repeated thermal cycles.
Immersion silver / tin	Alternative planar finishes	Storage environment, shelf life and assembly-process compatibility.
Hard gold contacts	Wear/contact function rather than general solderability	Selective plating area, thickness and connector requirements.

A release package that prevents avoidable clarification loops

Fabrication outputs with all copper, mask, legend and outline layers.
Plated and non-plated drill files, a drill map and finished hole requirements.
Fabrication drawing with units, dimensions, tolerances, material and finish.
Stackup table, impedance table, coupon requirements and approved exceptions.
Electrical netlist when required; distinguish bare-board electrical testing from assembly functional testing.
One revision identifier across files and a change summary from the previous release.

From RFQ to an approved build

First submit the design intent and quantity. Resolve CAM/DFM questions against one controlled revision, then approve the proposed stackup and impedance geometry. Agree inspection deliverables before manufacture. At receiving, compare the supplied reports and lot identification against the approved requirements rather than relying only on a visual inspection.

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