Header pin dimensions (thickness)

Thread Starter

Dritech

Joined Sep 21, 2011
869
Hi all,

I designed a PCB board which used standard header pins (pitch 2.54mm and thickness 0.65mm)
Unfortunately, upon receiving this PCB, I realized that I used the wrong pin hole dimensions (C-50-25) and the header pins won't fit.
Are there any header pins which have a pitch of 2.54mm but thickness which will fit in these holes? I already tried Mouser and RS, but the only filtering fields are the pitch and the pin length. no filters for different pin thicknesses.
Any suggestions of what can be done, apart from re--designing and re-ordering :) ?

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ElectricSpidey

Joined Dec 2, 2017
1,237
Drill them out.

I have also on occasion filed down pins on different things that wont fit into PCB holes, such as fuse blocks as such.

Of course this all depends on how many you need to do.
 
Last edited:

dl324

Joined Mar 30, 2015
11,527
Mouser and RS, but the only filtering fields are the pitch and the pin length. no filters for different pin thicknesses.
That's because the dimensions are fixed at 0.025".
Any suggestions of what can be done, apart from re--designing and re-ordering :) ?
It depends on how traces connected to the pads. If you have traces on both sides of the board, or have inner trace connections, the hack will be worse than redesigning the boards.

If you had used the standard header components in whatever program you used, they should have the correct hole size.
 

djsfantasi

Joined Apr 11, 2010
6,811
Drill them out.
...and make sure they’re soldered on both sides. Drill the holes out. Tin them on the top. Insert the headers. And solder them on the bottom. Ensure the pins are hot enough to melt the tinning on the top pads.

If the holes are plated through holes, drilling through them will remove the conductivity between the top and bottom. And if the board has more than two sides, through drilling likely won’t work reliably.
 

jpanhalt

Joined Jan 18, 2008
10,233

MrChips

Joined Oct 2, 2009
21,868
You forgot to take into account two things (1) fitting a square peg into a round hole and (2) the hole gets smaller after plating.
For header pins use 0.033" or 0.035" holes.
Edit: Go with 0.038" holes.

Depending on the diameter of the finished holes you might still be able to salvage the PCB.
0.025" drilled hole could end up being 0.021" after plating.

I would destroy a male pin header and extract single pins. It helps to heat up the pin in order to melt the surrounding plastic.
Then use a pair of needle-nose pliers and try forcing the pin into each hole, making sure to align the square pin to be square with the body the header. This should create a square hole to allow you to insert your header.

It is worth trying.
 

jpanhalt

Joined Jan 18, 2008
10,233
I would be reluctant to recommend brute force as the user may end up forcing the plated barrel and pad on the opposite side out. Then, there is a worse problem. Brass is easily machined. Before using brute force, I would just grind or file the corners off until it fits.
 

Thread Starter

Dritech

Joined Sep 21, 2011
869
Hi all,

Thank you for all the replies. I believe the best option is to drill as I have quite a few and forcing the pins may cause damage to the traces. For future reference, is 30 thou (0.762mm) good to use for these kind of header pins?

71585159496162.png
 

jpanhalt

Joined Jan 18, 2008
10,233
The diagonal size of a pin 0.025" square is .025 X 2^1/2 = 0.025 x 1.414.... = 0.03535..." ( as I stated above). You also need some room for the plating and slip.
 

djsfantasi

Joined Apr 11, 2010
6,811
Drilling works - IF YOU ARE AWARE OF WHERE PTH IS USED TO COMPLETE THE CIRCUIT.

Otherwise, drilling will create a cut in the trace and may render the circuit inoperable.
 

MrChips

Joined Oct 2, 2009
21,868
Before you send off your job to a PCB house you need to check a couple of things.

1) Find out if you need to specify drill size or finished hole size.
2) Before submitting the CAD files, check the tool sizes in the drill file. Make sure they match up with the desired hole sizes.

I have edited my previous post #7. I have used #62 drill in the past. Drill hole is 0.038" and finished hole is 0.035".
 

djsfantasi

Joined Apr 11, 2010
6,811
Just to add a couple of points. I’ve done this is the past. Some holes, I could force the pins in. It was a two-sided design where the PTH was necessary to complete the circuit. But for some reason, there were other headers where I couldn’t force the pins through. In this case, I did drill the holes out AND tinned the pins. In the latter case, soldering the pins melted the timning enough to complete the circuit.

Not that I did this on the prototype. The final PCB run had the proper size holes
 
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