How much clearance should you include in through-hole components holes?

• 0.1mm is too tight toward the high end if you’re designing for automatic insertion of parts with bent leads.
• Usually 0.8mm is okay for most leads except fat diode leads, for which you can use 1.0mm.
• Usually 1.3mm holes are specified for 1mm pins (for example on terminal block datasheets).
• Sometimes 1.5mm which is really, really loose.

If the leads are flat or square rather than round, you can go a bit tighter on the diagonal dimension, assuming a round hole. For really flat leads, it’s better to specify a slot.

If you’re using some kind of special part, such as a staked connector or press-fit part, pay attention to the tolerances.

Read More: Through Hole PCB Assembly

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