The items listed below should be reviewed for inclusion on each drawing to capture the product requirements and communicate to the supplier what is needed for the components to function and appear as the design intended.
General
- Part description, Part number & Revision
- Designer or person responsible for changes
- Release date
- Propietary / confidential identifier and IP owner
- Dimension basis (inches/ millimeters, etc)
- Dimensions to be verfied during intial run, set-up, or on-going production and any required inspection method
- Tolerance for each important dimension (see below)
- Approach for interpretting tolerances (e.g. ANSI Y14.5, AMSE, GD&T)
- Material called out, as appropriate (allowable regrind, glass fill, ESD compliance, UL94 V-0, alternates, etc or board layer stack)
- Part marking (p/n, rev, cavity, serial number, etc) and allowable methods (machine, etch, stamp, label, etc)
- Certification standards
- Physical product limits
- Special packaging, handling, or labeling
- Scale / ratio (1:32, 1:5, drawn to scale, etc)
- Revision hisotry
Tolerances can be specified in one or more of the following methods:
- Method 1: uniquely specified for each dimension
- Method 2: Can be ‘unless otherwise specified’ based upon number of decimal places for each dimension.
- Method 3: “Dimensions not called out in the drawing are to be taken from the 3D CAD file with a tolerance of +/- 0.XXX”
Mechanical
- Allowable draft angle & bend radii
- Finish and location restrictions (e.g. not in threaded holes), including surface roughness, texture, tool marks, burrs, gates, broken edges, corner radii
- Cosmetic requirements
- Testing required (salt spray, dye penetration, tensile strength, etc)
- Any special assembly methods or order of operations (welding requirements, etc)
- Views (isometric, top/bottom, side(s),etc.)
Electrical
- IPC Class or Mil-spec
- ESD Class (should be lowest required for components)
- Flammability requirements (UL94 V-0)
- Board material stack / tolerance including core and pre-preg
- Board thickess tolerance
- Surface finish (HASL, gold-plated, etc)
- Copper weight
- Drill registration, diameter, tolerance
- Annular ring minimums for PTH
- Soldermask color, material, hole fill, registration clearance, thickness, etc
- Silkscreen material, color, registration, height, thickness, etc
- Serialzation requirements
- Solderpaste (material, RoHS requirements)
- Bow/ twist tolerance
- Number of allowable x-outs / panel (percentage is ok - e.g. 30% or less)
- Depanalization methods allowed (mouse bites, pizza cutter, routing, etc)
- Final board dimensions with tolerance
- Wire diagram (for cable harnesses)
- Test requirements (TDR, controlled impedance, cross-sections, X-ray image retention, etc)
- Reliability requirements