How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together?

Wide iron tip, not narrow. You don't care if you reflow the adjacent pins, you only care about keeping the (already tinned) blue wire in the right place while the solder is wet.

And like riflery or photography, hold your breath out before the delicate bit, not in.

Alternatively, you may have better luck finding a via or trace that you can scrape the soldermask off with an Xacto knife than trying to hit the pins proper.

Part of the hardware design is to put test points on the board where they are needed and always build in enough diagnostic capability :-)...

Chris

You didn't state any specific dimensions so it's hard to answer with specifics.

Perhaps a hot air soldering station would be useful if you don't trust your narrow soldering tip. Hot air will reflow the adjacent pins. Using hot air is tricky if you've never done it before. It can be practiced.

I've found that the narrow Metcal tips just don't carry enough heat for good results for individual pin soldering.

JJS

don't control it).

ace, or for timing instrumentation) to a surface-mount IC where the pins ar e VERY close together. The pins are so close together that I can't solder a wire to it, even using high-power optics and the finest soldering iron ti p available.

t help with this?

You should be involved in the hardware specification development so that yo u can insert test points for the likely points you would like to access.

Otherwise you might be able to attach your probes more easily to a trace co nnected to an IC than the IC itself. You can scrape the solder mask off of a spot on a trace and solder to the trace with no risk of shorting to anot her point. If vias are not covered you can use them as an attachment point for wires.

Rick C.

You probably already have the illuminated magnifying glass.

Based on the qualities of the tch here that can do it, I'd say you need a surgeon's hands and lots of practice!

Good luck Ed

I always manage to solder wires, e.g.

:)

However if you are talking about actual pins like a QFP or MSOP then I have found there are miniature test hooks that work pretty well, better than I expected. They are usable with fairly small pitches. Certainly fine with 0.5mm pitch QFPs for example.

There are many types but e.g.

I'd suggest that being generous with flux will help here - there are times when there's enough heat in there, but not enough to break down the oxide. Flux can get the whole lot going. Jelly flux can be useful in staying where you want it until you get the iron in.

Theo

Around here I get back boards with "sorry, no space for your test points, ya know thats why we're using 0402 - but we'll solder on some test fly-wires for ya"...

Is that a metric or imperial package? Sounds a little bit ambiguous. ^_^

Gene.

Thanks, Theo. I was under the mistaken impression it was a heat problem. The oxide problem makes so much more sense now. Thanks for solving a lifelong mystery. - JJS

I recommend MG Chemicals 835 RA flux. You can get it in liquid or as a flux pen. I have a lot of prototyping parts from way back, and RA flux cuts through the accumulated metal oxide very well.

Cheers

Phil Hobbs

don't control it).

ace, or for timing instrumentation) to a surface-mount IC where the pins ar e VERY close together. The pins are so close together that I can't solder a wire to it, even using high-power optics and the finest soldering iron ti p available.

t help with this?

In the past, I used a Pace tool that was a titanium heating element. I coul d both hold the wire in place and reflow the solder. It was better if I tin ned the wire first and used a flux pen on both parts.

hot air pencil ans steady hands probably as good.