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How to choose drill size with known pin diameter?

Hi - does anybody have any suggestions for how to choose a drill size for a known diameter pin? For example I'm making a layout with a piece that has .02" diameter pins. Not only does the drill need to be a bit bigger than that just so that the pin can be put in without excessive force (and so that solder can flow through it) - but also since the hole will be plated it needs to be that much thicker. So - is there a good guideline for how to size such holes? Also - are there "standard" drill sizes, or is it best just to see what the board manufacturer uses? Thanks,

-Michael J. Noone

Reply to
Michael Noone
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When I order PC boards, I specify the finished hole size, and let the board shop determine the required allowance for plating. Normally, the smallest size I specify for component leads is .030 (for TO92 transistors), but usually use .035" for most parts (ICs, 1/4W resistors, etc.)

The finished hole size should be at least .010" larger in diameter than the lead.

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Peter Bennett, VE7CEI  
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Reply to
Peter Bennett

On Tue, 31 May 2005 16:30:17 -0500, Michael Noone wroth:

Some board manufacturers will deliver boards with specific hole diameters after plating. Some manufacturers only drill the original hole with the specified diameter and it's up to you to determine the finished, plated, hole diameter.

In short, pick a manufacturer based on other criteria, and then work with them to get the proper finished hole diameter. If they only drill the original hole to what you specify, they can tell you what the build-up due to plating will be.

Jim

Reply to
James Meyer

Hello Michael,

In addition to Jim's explanation: You should also find out what the manufacturer of your part specifies as the ideal hole diameter after plating. Else you might find that drill position tolerances and other deviations jam up the part, IOW it won't insert unless you force it. Also, solder may need to wick into there.

Regards, Joerg

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Reply to
Joerg

I choose pin dia +0.015" for finished diameter and +0.01" for plating thru, so with your 0.02" pins the drill diameter is 0.045". Now the cheap board house(Olimex) has only ... 0.039, 0.043, 0.051, ... without extra charge available, so I choose 0.043".

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ciao Ban
Bordighera, Italy
Reply to
Ban

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