“The leading cost driver in manufacturing of a printed circuit board is process yield. Many issues can be avoided by adopting sound Contract Review practices and thereby reducing the board’s cost. This table identifies design attributes that will result in the lowest possible designed cost. We realize that each PCB design is unique and that adhering to these guidelines is not always possible, but at least here’s a baseline from which to begin.”
Specification |
Standard |
Emerging Technologies |
| Annular Ring | ||
| Internal Minimum Pad Size | .016” larger than finished hole size. | .014” larger than finished hole size w/tear drop. |
| External Minimum Pad Size | .016” larger than finished hole size. | .014” larger than finished hole size w/tear drop. |
| * increase pad size accordingly for annular ring requirements greater than .001”. | * holes requiring greater than .001” copper (i.e. 2oz. Base plated to 4oz. Finish) require an additional .004” pad diameter | |
| Plane Layer Clearance | ||
| PTH & NPT hole Clearance to Plane | .030” larger than finished hole size. | .024” larger than finished hole size. |
| PTH & NPT hole to I/L Trace | .015” spacing | .012” spacing |
| Line Width & Space | ||
| I/L Line Width on 1 oz. Base Copper or Less | .005” standard | .004” |
| I/L Line Width on 2 oz. Base Copper | .008” minimum | .008” minimum |
| I/L Line Width on 3 oz. Base Copper or Greater | .012” minimum | .012” minimum |
| O/L Line Width on 1 oz. Base Copper or Less | .005” standard | .004” |
| O/L Line Width on 2 oz. Base Copper | .008” minimum | .008” minimum |
| O/L Line Width on 3 oz. Base Copper or Greater | .012” minimum | .012” minimum |
| I/L Feature to Feature on 1 oz. Base Copper or Less | .005” standard | .004” |
| I/L Feature to Feature on 2 oz. Base Copper | .008” minimum | .008” minimum |
| I/L Feature to Feature on 3 oz. Base Copper or Greater | .012” minimum | .012” minimum |
| O/L Feature to Feature on 1 oz. Base Copper or Less | .005” standard | .004” |
| O/L Feature to Feature on 2 oz. Base Copper | .008” minimum | .008” minimum |
| O/L Feature to Feature on 3 oz. Base Copper or Greater | .012” minimum | .012” minimum |
| Trace to Plane Spacing on I/L or O/L | .008” minimum | .008” minimum |
| Feature to Board Edge | .010” min I/L & O/L * exclude tabs | .008” min I/L & O/L * exclude tabs |
| Feature to Score Edge | .020” minimum | .015” minimum |
| Carbon Ink | ||
| Carbon Ink size to Copper Feature | .015” larger than feature size. | .010” larger than feature size. |
| Carbon Ink to Carbon Ink Spacing | .015” minimum | .013” minimum |
| Carbon Ink to Solder Mask | .005” minimum | .005” minimum |
| Solder Mask | ||
| LPI Conductor Overlap | .003” min over conductor edge. | .002” min over conductor edge. |
| LPI Mask Clearance | .006” larger than O/L feature size. | .004” larger than O/L feature size.* |
| LPI Mask Web* less than 4mil web may result in loss of mask between SMT pads. | .004” minimum width | .003” minimum width * Decrease clearance to 5mil, then web to 3.5mil, then clearance to 4mil, etc. |
| Nomenclature | ||
| Silk Screen Process (legend ink) | .008” minimum aperture | .006” minimum aperture |
| Etching Process (copper) | .010” minimum aperture | .010” minimum aperture |
| Font Height | .065” minimum height | .045” minimum height |
| Distance from Feature (clipping) | .006” min from pad, SMT, etc. | .006” min from pad, SMT, etc. |
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