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PCB layout: The efficient laying out of traces on a PCB is a
complex skill, and requires much patience. This task has been
made vastly easier with the advent of readily available PCB
layout software, but it is still challenging.
1 Copper Thickness
2 Trace Width
6 Reference Handbook
9 further reading
11 External links
11.1 Manufacturer design tips
11.2 Other external links
12 Further reading
 Copper Thickness
The vast majority of PCBs are manufactured with "1 ounce
copper" on the outer layers. (If there are inner layers,
they are almost always manufactured with "1/2 ounce copper"[citation
The thickness of the copper layer on the PCB affects the
behaviour of the circuit. PCB copper thickness is usually
measured in ounces per square foot, or frequently, just ounces.
It can also be given in micrometres, inches or mils. The measurements
for common thicknesses are given below.
oz/ft² μm in mil
0.5 17.5 0.0007 0.7
0.75 25.5 0.0010 1.0
1 35 0.0014 1.4
2 70 0.0028 2.8
3 105 0.0042 4.2
As always, the thickness of a thin slab of metal with a given
top surface area is always exactly
The area is "1 square foot" (144 square inches),
the density of copper is 8.96 mg/mm^3 = 5.18 ounce/(inch^3),
and usually the mass is "1 ounce of copper",
 Trace Width
Different widths of traces have different properties that
could affect the operation of the circuit. For, example, a
thin trace has a higher resistance than a thick one, and can
therefore carry less current or will heat up more for the
Due to the large number of tables and charts, this information
is presented on different pages:
For current capacities, see Trace Current Capacity.
Most manufacturers can manufacture a minimum trace width of
0.010 inch. (Many can manufacture traces 0.008 inch wide).
Such minimum-size traces are more than adequate for most digital
and analog signals.
Summary: Most design engineers still believe that with a good
shielded enclosure, well-shielded cables and high-performance
ferrite sleeves, EMI compliance will be a straight forward
task. This paper demonstrates experimentally that a poor PCB
layout can cause electronic product to fail EMI specification
badly even with all these fixes.
The manufacturer of each part recommends a "footprint",
a copper pattern for the part to be soldered to the PCB.
Most PCBs have many holes drilled in them.
Most PCBs with more than 1 layer have every hole "plated-through-hole",
even holes that don't need to be plated through-hole (tooling
holes and some through-holes). They do that because it takes
extra effort to plug "non-plated" holes before throwing
the PCB into the plating bath.
There are 3 general types of holes
All work done in the United States.
Impact of PCB layout design on final productapos;s EMI compliance
Kye Yak See; Oswal, M.; Khan-ngern, W.; Canavero, F.; Christopoulos,
C.; Grabinski, H.
Electromagnetic Compatibility, 2006. EMC-Zurich 2006. 17th
International Zurich Symposium on
Volume , Issue , 27 Feb.-3 March 2006 Page(s): 553 - 556
Digital Object Identifier
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