Contents [hide]
1 Copper Thickness
2 Trace Width
3 footprints
4 holes
5 layers
6 Reference Handbook
7 layers
8 traces
9 further reading
10 references
11 External links
11.1 Manufacturer design tips
11.2 Other external links
12 Further reading

[edit] 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 needed] ).

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",

[edit] 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 same current.

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.

[edit] footprints
The manufacturer of each part recommends a "footprint", a copper pattern for the part to be soldered to the PCB.

[edit] holes
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
est. 1995At Electronic Prototypes, Inc. we will work with you to determine the most reliable, safe and cost effective board.