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Drilling out through holes on PCB

post #1 of 14
Thread Starter 

Simple question: Is it possible to drill out the through hole on a PCB to make it slightly larger, and still have everything work? Even if the trace metal is only on the surface of the through hole and is removed in drilling, I should be able to fill the hole with solder to reconnect to the intersecting traces right? Or will the solder probably not flow like that? Or will there be other problems?


Edited by cheapskateaudio - 11/6/11 at 11:15pm
post #2 of 14
Maybe. Some holes are plated all the way through. You could also lift a pad on the other side when the bit comes through. Personally, I'd use a thin round file to expand it.

Though the best way would probably be to mount the component to solder terminals of the PCB and run jumper wires to the PCB.

Just curious, what are you mounting that has such big leads?
post #3 of 14
Thread Starter 


 

Quote:
Originally Posted by Uncle Erik View Post

Maybe. Some holes are plated all the way through. You could also lift a pad on the other side when the bit comes through. Personally, I'd use a thin round file to expand it.
Though the best way would probably be to mount the component to solder terminals of the PCB and run jumper wires to the PCB.
Just curious, what are you mounting that has such big leads?

 

Capacitors, but I figure it could be useful if you want to insert something into a circuit by drilling a hole through the board on a trace and filling with solder. Right now the caps are surface mounted, its just a little precarious and if jostled over time in a portable situation might break off. 

 

 

post #4 of 14

I would follow UE's advice.  I tried this when I was modding a Lite Dac-Ah (to fit the huge leads on the Audience Caps) and had a hell of a time repairing the board and getting everything to work. 

post #5 of 14
Thread Starter 


 

Quote:
Originally Posted by ecclesand View Post

I would follow UE's advice.  I tried this when I was modding a Lite Dac-Ah (to fit the huge leads on the Audience Caps) and had a hell of a time repairing the board and getting everything to work. 


Ok, I'll probably take UE's suggested route for now... but you did eventually get it to work? Was it just a matter of getting the solder to flow into the drilled out hole properly? I wonder if you drilled at an angle if it would improve the odds of getting a good contact with the trace..

 

post #6 of 14

I've done it before, but the holes only needed to be drilled out slightly, and there was still thru-hole plating left. I have a drill press and a pretty complete set of PCB bits also. If you have a DMM, you should be able to ohm it out to verify whether any plating is left or not. If not, if you can solder both sides (top and bottom), that will work as well. On double sided PCBs that I have etched, I will take cut resistor leads and drill a small (#60 or so) hole next to the pads on stuff like electrolytic caps, etc. where you don't have access to the top side, and solder these to the pads on both sides. When the component goes in, the resistor lead provides the connection from top to bottom.

post #7 of 14
Thread Starter 


 

Quote:
Originally Posted by Pars View Post

I've done it before, but the holes only needed to be drilled out slightly, and there was still thru-hole plating left. I have a drill press and a pretty complete set of PCB bits also. If you have a DMM, you should be able to ohm it out to verify whether any plating is left or not. If not, if you can solder both sides (top and bottom), that will work as well. On double sided PCBs that I have etched, I will take cut resistor leads and drill a small (#60 or so) hole next to the pads on stuff like electrolytic caps, etc. where you don't have access to the top side, and solder these to the pads on both sides. When the component goes in, the resistor lead provides the connection from top to bottom.


Good idea. I was thinking of getting this for drilling, reviews seem good: http://www.micromark.com/MicroLux-Benchtop-Variable-Speed-Mini-Hobby-Drill-Press,8283.html

 

 

 

post #8 of 14
Quote:
Originally Posted by cheapskateaudio View Post


 


Good idea. I was thinking of getting this for drilling, reviews seem good: http://www.micromark.com/MicroLux-Benchtop-Variable-Speed-Mini-Hobby-Drill-Press,8283.html

 

 

 



I considered the MicroLux but ordered a Proxxon drill instead.  I wanted to be able to drill larger holes in panels than the MicroLux would handle.  If you get the MicroLux I would love to know what you think of it.

 

 

post #9 of 14

The real issue is when tracks approach a component on the top (component) side of the board and the component hides the hole when it's placed in position. Often with discreet components you can mount them a little way off the board, but sometimes you want them to sit down close to keep the lead inductance to a minimum, and some things, like DIL sockets, just completely cover the donut and if the track joins on the top, you're out of luck. This is something that makes home-made PCBs slightly less versatile than bought-in, you often have to take tracks through to the bottom with a via to make connection possible at all. I use a lot of surface mount, although they have problems of their own.

 

w

post #10 of 14

The only kind of drill you should ever get anywhere near a PCB is called a pin vise. It's a manual, hand held drill, and comes with a variety of

very small bits. I got mine from Radio Shack, but I didn't find it on their website. If there's a store nearby, you might check to see if they still

have one. If not, any hobby shop should carry them.

 

I've used mine several times to enlarge PCB holes without any problems, but if the board is through-plated, and has more than two layers,

there could be trouble. If it's just two layers, you should be OK, but make sure that you solder on both sides of the component just to be safe.

post #11 of 14

These are what I buy and use, in a Delta 10" drill press I got at Lowes for ~$100. Runout is fine on it, though maybe not as nice as the one the OP posted.

 

http://drillbitcity.com/catalogue/10_piece.asp

 

I have the 60-69, 50-59 and I believe the 40-49 sets. The 60-69 gets the vast majority of the work.

 

And yes, if it is more than a 2 layer board, I would not do this unless you are absolutely sure the holes are not connected to an internal layer. If you only have to enlargen it slightly, you may still have through-hole plating left (I did). If this is an O2 board, you have access to the Gerber files used to make the boards, so use a Gerber viewer (such as GerbView) and take a look at the layers around the hole(s) you want to drill out. It is a 2 layer board.

post #12 of 14

I got this set from Drill Bit City.

post #13 of 14

^ A bit off topic, but do you use the router bit in the set you pointed to?

 

DSC00138.jpg

 

I've never had a good method for cutting the PCB material when I etch my own boards. I've wondered how well something like that worked and if it would work in a drill press (don't have a router).

post #14 of 14

I have not used the router bit yet.

The one in the set would be best used in a CNC router.

You could use it in a drill press...just raise the table to

the correct height. Clamp a guide to the table and you

have a poor mans router wink_face.gif

 

I use a tile saw to cut my boards...works very well but you should

protect yourself from breathing the dust.

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