We have collected
some helpful odds and ends for you
Download Easytrax
- A basic but functional CAD system
Track
Width by Current
Conductor Spacing
Drill
size suggestions for components
These are a few of the issues that bring us
to the phone most often. We hope that these files are
useful. Of course we can't leave you to your own devices
yet. If you have not done much or any printed circuit
design, we have a few more suggestions for you:
1. Place power and ground traces
first. These are the least tolerant of impedance due to
bad routing. Power and ground should be wide traces and
equal ( like .030" ) to insure low noise. A major cause of
failure of new designs is poor power supply.
2. Ground and Power planes can be cross
hatched to create a screen effect. This improves
lamination and frequency response of your power
distribution. The trace width can be .010" to .015" and
the spacing should be greater than the spacing selected.
If you have .010" lines, there should be .015" or so between
them.
3.The use of CAD auto-routers should be
restricted to prevent excessive numbers of vias, breaking the
lines of a bus, or mixing signals ( such as analog and digital )
by capacitive or inductive coupling.
4. Consider the fundamentals as most
important: A current should be allowed to return to its
origin. Different grounds (digital analog and chassis)
should be isolated except where they may come together at ONE
point. Impedances should match in both directions.
These concepts may seem obscure but if not
considered, they can mean
disaster.
