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

On 6/27/2018 4:40 PM, Theo wrote:
> John Speth <johnspeth@yahoo.com> wrote:
>> I've found that the narrow Metcal tips just don't carry enough heat for
>> good results for individual pin soldering.
> 
> 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.

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

On 06/28/18 15:03, John Speth wrote:
> On 6/27/2018 4:40 PM, Theo wrote:
>> John Speth <johnspeth@yahoo.com> wrote:
>>> I've found that the narrow Metcal tips just don't carry enough heat for
>>> good results for individual pin soldering.
>>
>> 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.&nbsp; Jelly flux can be useful in staying 
>> where
>> you want it until you get the iron in.
> 
> Thanks, Theo.&nbsp; I was under the mistaken impression it was a heat 
> problem.&nbsp; The oxide problem makes so much more sense now.&nbsp; 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

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Tuesday, June 26, 2018 at 11:51:35 AM UTC-5, David T. Ashley wrote:
> We do embedded software, but the hardware is produced by our customer (we don't control it).
> 
> Sometimes we need to attach a wire (for monitoring a serial or I2C interface, or for timing instrumentation) to a surface-mount IC where the pins are 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 tip available.
> 
> Are there any special tools, equipment, training, or techniques that might help with this?
> 
> Thanks!

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

hot air pencil ans steady hands probably as good.