Soldering near a filled plane

Jul 15, 2011 10 Replies

Gentlemen:



I recently ordered a PC board from Express PCB and, to save money, I got their economy-type board that has no solder mask. I have done this before for small, prototype projects with good results.



But this time I designed the circuit with a filled ground plane around the traces. The CAD program automatically leaves spaces around the traces, but not very big spaces. Now I am finding it extremely difficult to solder without bridging onto the ground plane.



Are there any soldering tricks that will help me salvage this board, or do I have to pay for a new one with a solder mask?



Don


I feel your pain. A few months ago, our new boss decided he'd have us save $20 and leave off the solder mask on a prototype board. It was a fairly simple board but did have a half-dozen TSOPs on it. Our tech wasn't a happy camper. To save that $20 he wasted several hours; good use of time.

My suggestion is to acknowledge the lesson learned and suck it up. ;-)

A paste/liquid flux might help by assisting the solder in "wetting" the traces and the ground plane area. It's probably okay, at least in most spots, for there to be solder on the ground plane as long as it doesn't bridge to a trace. The flux should help by making the copper areas more attractive to the solder so that it beads up rather than laying there in a passive puddle.

Of course, a small tip on the iron and fine gauge solder will help but I assume you've already tried that?

Rich Webb Norfolk, VA

Re-order the board with a solder mask, and chalk it up to experience.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 email: hobbs (atsign) electrooptical (period) net http://electrooptical.net
[snip]

Put nail polish on the ground plane? Fumes might be an issue if the iron hits it.

Kapton tape, if you can find/afford it?

That's how I order my boards, and I really don't have much problem. Use a clean, fine-tip iron, a good magnifier (I use an assembly microscope), and keep the solder-wick handy for when the solder just wants to bridge.

I find that big uninsulated solder plane to be handy when I need someplace to put a ground probe, or if I need to dead-bug bits of circuit onto a prototype board.

Tim Wescott Control system and signal processing consulting www.wescottdesign.com

Spray the board with clear KRYLON

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Direct contact with the iron vaporizes the coating while leaving outer areas protected.

try drawing a solder mask on with a permanent marker, or a paint pen.

?? 100% natural

Well, I tried spraying it with conformal coating and it seems to work well. Thanks for all your help guys.

Don

Uline.com sells Kapton tape.

It's not expensive or hard to find. 18 rolls of 1/2" x 108' Kapton tape is $30 at DigiKey. A single roll of the same is about $6 at Amazon. Wider and narrower is also readily available.

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