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This might be a ridiculous question to ask - but I have made a mistake in a new library I created in Eagle for a component. The drill diameter of the plated holes for the component leads should have been 0.04" but I missed the fact that the default diameter of pads inserted by Eagle is ~0.025". The PCB has come back and lo & behold, I cannot fit my component leads. What are my options (if I need to get a proto build done immediately)?

The only option I can think of is: to file away the component leads until they fit into the hole.

Is there a better way?

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    \$\begingroup\$ Cut short & surface mount ... \$\endgroup\$ – brhans Apr 30 '15 at 14:33
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    \$\begingroup\$ You've gotten good answers.. in the future it's good to have a checklist that includes checking things like component hole sizes. I like to have a look at the ASCII drill file directly. You might also be able to catch this when inspecting the Gerbers if you've imported the drill file. \$\endgroup\$ – Spehro Pefhany Apr 30 '15 at 14:52
  • \$\begingroup\$ What component is this? If it's a DIP, folding the legs under the package after cutting them a bit shorter makes for a nice surface mount package. \$\endgroup\$ – RJR May 6 '15 at 6:57
  • \$\begingroup\$ I also recommend drilling a larger hole, but offset, so that more than 1/2 of the PTH material is not removed. \$\endgroup\$ – Guill May 8 '15 at 20:28
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This is a one-off prototype, so doesn't need to withstand end-user mechanical abuse. I would probably trim the leads a bit, then set the ends of the leads on the pads, using the holes to align them. Now use solder blobs to hold the component in place.

The leads aren't going through the holes, but the ends are sitting on top of them. The solder guarantees a connection and holds the part in place. The part will be held much more weakly than if the leads were going through the holes, but for testing your circuit it should be good enough. If you really need more mechanical strength in your prototype, glob a lot of hot glue around the pins extending all the way up to the bottom of the part.

Before you forget, go into Eagle now and fix the hole and pad sizes for that part in your library. This can be easy to forget before the next revision when you're knee deep in changing other parts of the circuit.

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  • \$\begingroup\$ Could you sand the leads to be the right diameter? \$\endgroup\$ – Cole Johnson Apr 30 '15 at 15:04
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    \$\begingroup\$ @ColeJohnson That would work too, and copper leads are very easy to file, but at such widths it becomes a tricky endeavor. I'm 50/50 on filing the leads, frankly said. \$\endgroup\$ – Kuba Ober Apr 30 '15 at 15:06
  • \$\begingroup\$ @KubaOber well, obviously don't file the entire lead. Just enough so the component is at the right height. Then you can solder and trim on the underside. Of course, I'd only do so with cheap components like resistors and capacitors. More "expensive" things like ICs, I'd probably just solder to the top. However, I'd most likely just reorder the PCB if it's cheap enough \$\endgroup\$ – Cole Johnson Apr 30 '15 at 15:21
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You could trim the leads short, and solder thinner solid wire to the stub leads. If you want good reliability, you should wind one end of the thinner wire on the stub leads or a slightly oversize mandrel, as if you were winding a spring. This will provide an order of magnitude larger stressed area for the solder, leading to a much more resilient joint.

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If it is only a protoboard and doesn't need to look the best you can solder a 0.025 wire into the hole. Then solder your leads to that wire. I've done it when I had a similar situation and it worked just fine, just didn't look very good.

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You have a few options:

  • File the leads down.

  • Drill the hole bigger. A Hex shank drill bit works great by hand. Or exacto or dremel.

  • Cut and bend the leads to surface mount.

  • Cut and solder thinner leads or a wire. Depending on the part, it can be dead bug style somewhere else with wires going to the pcb.

Personally, making the hole bigger with a drill bit is the way to go. Unless the size difference is enough that you loose the copper around the hole. You could also combine making the hole bigger and the leads thinner.

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  • \$\begingroup\$ +1 for drill the holes bigger. It's simple if tracks aren't tiny. \$\endgroup\$ – FRob Apr 30 '15 at 15:26
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    \$\begingroup\$ Depending on the amount of layers and present clearance drilling can do not so nice things to the inner layers \$\endgroup\$ – PlasmaHH Apr 30 '15 at 15:43
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    \$\begingroup\$ @plasma of course, I'm assuming single or dual layers. It's more complicated with multiple layers but op has the layout, so he knows if this can be good or bad. \$\endgroup\$ – Passerby Apr 30 '15 at 15:46
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    \$\begingroup\$ One does need to be careful if the hole is plated through and is connecting traces on both sides -- the solder on the lead must make good contact on both sides. \$\endgroup\$ – Hot Licks May 2 '15 at 12:25
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    \$\begingroup\$ Drilling a hole larger may well damage PTH barrel integrity. IF top and bottom soldering are then used this may be acceptable but great care is needed. \$\endgroup\$ – Russell McMahon May 6 '15 at 2:38
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One potential solution which does not seem to have been suggested is to mechanically "extrude" the lead ends by cutting the components to about correct length and then "squashing" the ends with pliers or vice grips. This is slowish and annoying and not attractive if the number of leads is large BUT it does actually work and gives a result which is probably better and cosmetically nicer than most alternatives.

Compression usually requires at least two "crimps" at right angles and possibly more. The tool used needs to be able to grip the thin lead well and apply force somewhat evenly. The overall process may be rather slow.


Drilling a hole larger has been suggested.

This will almost certainly remove the plated PTH barrel.
In your case the difference from 0.025" to 0.040" is 0.0075" in each wall and probably a bit less if you drill them so the new leads are a tight fit - but probably still 0.005" per wall or about 125 micrometres. As PTH barrel plating thickness is usually in the 25 to 50 micrometre range, drilling out to size will remove all PTH barrel plating.

Destroyed PTH continuity on 2 layer (double sided) boards can be replaced by top and bottom soldering to pins going through drilled out holes. This may be acceptable but great care is needed.

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