Circuit Boards Specifications
PCB designers often haven’t been in a printed circuit board manufacturing setting. With a good design there are processing limitations to be considered to build a quality product consistently. When considering your PCB design, using a Free DFM service such as Epec’s will save you cost, time, and prototyping.
Standard | Advanced | |
---|---|---|
Annular Ring - holes are drilled larger than the finished size required to meet the tolerances. 0.005 over the finish size in most cases. +\-0.003 is the standard plated hole tolerance. | ||
Internal Minimum Pad Size | 0.014" larger than finished hole size | 0.012" larger than finished hole size w/tear drop. Half-ounce ONLY |
External Minimum Pad Size | 0.014" larger than finished hole size | 0.014" larger than finished hole size w/tear drop. Half-ounce ONLY |
Increase pad size accordingly for annular ring requirements greater than 0.001" such as CLASS III product or press fit holes. | ||
Holes requiring greater than 0.001" copper (0.0007 per IPC) - (i.e. 2oz base plated to 4oz finish) require additional 0.004 pad diameter. | ||
Plane Layer Clearance | ||
PTH & NPTH Hole Clearance to Plane | 0.030" larger than finished hole size | 0.020" larger than finished hole size (0.10" per side over FHS) |
PTH & NPTH Hole to Inner Layer Trace | 0.015" Spacing | 0.010" Spacing (edge-to-edge) |
Line Width and Space - mixed copper technology is not included in the parameters below. | ||
Inner layer width on 1/4 ounce copper | Minimum -0.004" | Minimum -0.003" |
Inner Layer Line width on H ounce copper | Minimum -0.003" | Minimum -0.0025" |
Inner Layer Line width on 1 ounce copper | Standard -0.005" | Minimum -0.004" Half-ounce ONLY |
Inner Layer Line width on 2 ounce copper | Minimum -0.008" | Minimum -0.008" |
Inner Layer Line width on 3 ounce base copper or greater | Minimum -0.012" | Minimum -0.012" |
Outer Layer Line width on H ounce base copper | Minimum -0.004" | Minimum -0.004" |
Outer Layer Line width on 1 ounce base copper | Minimum -0.005" | Minimum -0.004" Half-ounce ONLY |
Outer Layer Line width on 2 ounce copper | Minimum -0.008" | Minimum -0.008" |
Outer Layer Line width on 3 ounce base copper or greater | Minimum -0.012" | Minimum -0.012" |
Inner layer Feature to Feature on 1 ounce or less base copper | Minimum -0.005" | Minimum -0.004" Half-ounce ONLY |
Inner layer Feature to Feature on 2 ounce Base Copper | Minimum -0.008" | Minimum -0.008" |
Inner layer Feature to Feature on 3 ounce copper or greater | Minimum -0.012" | Minimum -0.012" |
Outer layer Feature to Feature on 1 ounce or less base copper | Minimum -0.005" | Minimum -0.004" Half-ounce ONLY |
Outer layer Feature to Feature on 2 ounce Base Copper | Minimum -0.008" | Minimum -0.008" |
Outer layer Feature to Feature on 3 ounce copper or greater | Minimum -0.012" | Minimum -0.012" |
Trace to Plane Spacing | Minimum -0.008" | Minimum -0.008" |
Feature to Board Edge *does not include tabs | Minimum -0.010" | Minimum -0.008" |
Feature to Score Edge | Minimum -0.020" | Minimum -0.015" |
Solder Mask - Liquid Photo Imageable Mask. Some color mask such as White, Black, or Blue have additional requirements. | ||
LPI Conductor Overlap | 0.015" Larger Than Feature Size | 0.010" Larger Than Feature Size |
LPI Mask Clearance | 0.015" Minimum | 0.013" Minimum |
LPI Mask Web | 0.005" Minimum | 0.005" Minimum |
Less than 4 mil web between component pins may result in loss of mask between SMT pads. | Decrease clearance to 5 mil, then web to 3.5mil, then clearance to 4 mil, etc. | |
Silkscreen | ||
Silk Screen Ink | 0.008" minimum aperture | 0.006" minimum aperture |
Copper Features (ETCHED TEXT) | 0.010" minimum aperture | 0.010" minimum aperture |
Font Height | 0.065" minimum height | 0.045" minimum height |
If the specifications of a board design fall into the advanced category, it may be subject to additional charges.