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.
Reply by Phil Hobbs●June 28, 20182018-06-28
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. 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
>
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.nethttp://hobbs-eo.com
Reply by John Speth●June 28, 20182018-06-28
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
Reply by Evgeny Filatov●June 28, 20182018-06-28
On 28.06.2018 4:31, Dave Nadler wrote:
> On Tuesday, June 26, 2018 at 3:40:48 PM UTC-6, Chris wrote:
>> Part of the hardware design is to put test points on the board where
>> they are needed and always build in enough diagnostic capability :-)...
>
> 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.
Reply by Dave Nadler●June 27, 20182018-06-27
On Tuesday, June 26, 2018 at 3:40:48 PM UTC-6, Chris wrote:
> Part of the hardware design is to put test points on the board where
> they are needed and always build in enough diagnostic capability :-)...
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"...
Reply by Theo●June 27, 20182018-06-27
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.
Theo
Reply by John Devereux●June 27, 20182018-06-27
dashley@gmail.com writes:
> 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?
>
On Tuesday, June 26, 2018 at 12:51:35 PM UTC-4, 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 to a surface-mount IC
>
> Are there any special tools, equipment, training,
> or techniques that might help with this?
>
> Thanks!
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
Reply by ●June 26, 20182018-06-26
On Tuesday, June 26, 2018 at 12:51:35 PM UTC-4, 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?
You should be involved in the hardware specification development so that you 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 connected 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 another point. If vias are not covered you can use them as an attachment point for wires.
Rick C.
Reply by John Speth●June 26, 20182018-06-26
> 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?
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