Design for Manufacturability

The leading cost driver of a manufacturing a printed circuit board is process yield. Many issues can be avoided by adopting sound DFM practices and thereby reducing the board’s cost. This table indicates design attributes that will result in the lowest possible designed cost. We realize that each PCB design is unique and that adhering to these guides is not always possible.

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.