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ALLPCB TEAM September 19th, 2018
The way of determining annular ring width for thru-hole pads
When placing thru-hole components on a pcb, how to determine what the annular ring width should be?
If it is single layer pcb, the adhesive under the pad has to provide a lot of strength, so you probably want to go as high as 2mm annular ring or more on a part requiring strength such as a switch, terminal block, coil, etc. If there is not enough room to get appropriate clearances you can use a non-round pad and still get some of the benefit.
I normally go for 0.3mm but have been known to sneak em down to 0.25mm. The larger is fine. This is for low to medium current, anything greater requires a progressive increase in the hole diameter and a bit more meat on the annular ring. It also depends on the accuracy of your pcb supplier.
At least 10 mils annular ring is better for manufacturability, and a bit bigger than that is even better.
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