Doug,
In researching the book that I am writing for Kluwer, Robust Electronic
Design Reference, I ran across the following booklet:
Lund, Preben, How to Design Printed Circuit Boards for UL
Recognition. Westlake Village, CA: Bishop Graphics, 1983.
In my manuscript, I discuss UL Recognition of PCB's on pages G-15 and
G-16. Basically, a UL Recognition Card ("Yellow Card") issued by UL to
a printed circuit board (PCB) vendor covers:
* The laminate, conductor, soldermask, surface finish, and legend
materials to be used, and acceptable alternatives.
* The vendor's manufacturing process.
* The design rules to be followed, including:
- Minimum trace width for "Midboard Conductors".
- Minimum trace width for "Edge Conductors".
- Minimum annular ring on vias and plated-through holes.
- Maximum Unpierced Area.
- Maximum operating temperature.
- Minimum thicknesses for base laminate, C-stage laminates, B-stage
laminates, and finished PCB's.
- Conductor thickness.
If you would like a deeper understanding of what a "94V-0" rating
represents, I suggest you read
Grand, Arthur F., and Wilkie, Charles A., Fire Retardancy of
Polymeric Materials. New York: Marcel Dekker, 2000.
John Barnes KS4GL, PE, NCE, ESDC Eng, SM IEEE
dBi Corporation
http://www.dbicorporation.com/
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