| Due to an foul up on my part, a circuit board ECO snuck up on me and I have a solder paste stencil that doesn't quite match the board. Two pads are off by about half a pad each. | | Can the solder paste stencil be modified? If so, what is the technique and how long would a patch hold up? | | I need a temporary fix only until I can get a new stencil. | | Thanks for any advice you have.
Bernie,
I've had to modify stencils in the past before, so don't feel like the lone stranger. Be advised though, this is just a temporary fix, and you may wind-up having to touch-up the location though, but then you may get lucky and accomplish the modification where it'll work just fine, but at least you're not D.I.W. (dead in the water..ol' navy term,hehehe). By the way, I've only tried something like this with passive pads, and only down to 0805's...if it's anything else, forget it.
I've always used a Dremel Tool, got me a nice sharp bit whose diameter is close to the pad size or just a little smaller, and done it that way. The key is having a very sharp bit, and having patience. You don't want to force the bit at all you want to let it cut itself through the foil, otherwise you'll deform the metal and have a bump that will protrude out and hold the stencil up off the board. I'll use calipers to determine where I'm going to drill by measuring the board and then transfering my measurements to the stencil using an existing aperture and pad on the board as a reference to base the measurement off of.
In your case it sounds like it'll be fairly easy just to enlarge the holes that you have and then use some very small peices of kapton tape to mask off the part of the opening that is not over the pads...it's a little trying to get the tape placed where you want it, but if you have a clean surface when you place the tape it'll hold up enough to where you can use the stencil. You may have to replace the tape a time or two while using the stencil.
I know this just some bubble-gum and baling wire, but I've done this to get me out of a jam a few times...
-Steve Gregory- | | Bernie |
reply »