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

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  How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? dashley@gmail.com - 2018-06-26 09:51 -0700
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2018-06-26 10:21 -0700
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2018-06-26 22:40 +0100
      Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Dave Nadler <drn@nadler.com> - 2018-06-27 18:31 -0700
        Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Evgeny Filatov <evgeny.filatov@ieee.org> - 2018-06-28 13:10 +0300
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? John Speth <johnspeth@yahoo.com> - 2018-06-26 17:06 -0700
      Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Theo <theom+news@chiark.greenend.org.uk> - 2018-06-28 00:40 +0100
        Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? John Speth <johnspeth@yahoo.com> - 2018-06-28 12:03 -0700
          Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2018-06-28 20:13 -0400
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? gnuarm.deletethisbit@gmail.com - 2018-06-26 19:29 -0700
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? Ed Prochak <edprochak@gmail.com> - 2018-06-27 09:53 -0700
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? John Devereux <john@devereux.me.uk> - 2018-06-27 20:28 +0100
    Re: How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together? 1 Lucky Texan <1luckytexan@gmail.com> - 2018-08-03 09:47 -0700

#27854 — How to Solder a Wire to Surface-Mount IC With Pins VERY Close Together?

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!

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#27855

On 06/26/2018 09:51 AM, dashley@gmail.com 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!
> 

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.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.

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#27856

On 06/26/18 17:51, dashley@gmail.com 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!

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

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#27862

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"...

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#27863

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.

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#27857

> 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

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#27861

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

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#27864

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

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#27865

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.net
http://hobbs-eo.com

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#27858

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.

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#27859

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

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#27860

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?
>

I always manage to solder wires, e.g.

<https://ee.devereux.me.uk/ADS7947.jpg>

 :)

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.

<https://www.digikey.co.uk/product-detail/en/e-z-hook/X2015BLK/461-1000-ND/528221>


-- 

John Devereux

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#27934

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.

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