Re: ChipQuik Troubles

[Paul Koning via cctalk]

> On Jul 5, 2017, at 6:17 PM, Chuck Guzis via cctalk  
> wrote:
> 
> On 07/05/2017 01:42 PM, Rob Jarratt via cctalk wrote:
>> I bought some ChipQuik recently and managed to successfully remove a 74LS125
>> with little trouble. Today I have come to trying to desolder another similar
>> sized chip, but try as I might I just cannot get it to work. The ChipQuik
>> just balls up and won't "take" to the pins. I applied plenty of the flux
>> supplied with the ChipQuik, but I wonder if I applied too much?
> 
> Will the pins take "regular" solder?  I wonder if there might not be
> some coating on them...

Real solder works just fine.  I've assembled boards that were made to lead-free 
standards, using lead-free parts -- since that's all you can get now.  On the 
advice of a board rework technician I used real solder.  Her comment amounted 
to that real solder always works better, and that lead-free solder is something 
you put up with if you have to.

paul

RE: ChipQuik Troubles

[Rob Jarratt via cctalk]

> -Original Message-
> From: Jon Elson [mailto:el...@pico-systems.com]
> Sent: 05 July 2017 23:25
> To: r...@jarratt.me.uk; Rob Jarratt <robert.jarr...@ntlworld.com>; General
> Discussion: On-Topic and Off-Topic Posts <cctalk@classiccmp.org>
> Subject: Re: ChipQuik Troubles
> 
> On 07/05/2017 03:42 PM, Rob Jarratt via cctalk wrote:
> > I bought some ChipQuik recently and managed to successfully remove a
> > 74LS125 with little trouble. Today I have come to trying to desolder
> > another similar sized chip, but try as I might I just cannot get it to
> > work. The ChipQuik just balls up and won't "take" to the pins. I
> > applied plenty of the flux supplied with the ChipQuik, but I wonder if I
applied
> too much?
> >
> >
> >
> >
> The solders may be incompatible.  What are you trying to do, replace a
> defective chip to make an old board work?
> 


I *think* it may be defective, I have a replacement for it anyway.


> You DON'T need ChipQuik.  If the board was soldered with lead-free solder,
> diluting the solder with PbSn solder makes it easier.  If it is already
done with
> leaded solder, then you just need a little technique.  For surface mount
parts,
> use an Xacto knife under the pins, and lift them one at a time while
touching
> with the iron. Generally, I remove as much solder as I can with solder
wick first,
> then lift the pins.  When one row of pins are lifted, the chip can be
flexed a few
> times and the other row of pins break off.  The remaining pins can be
swept off
> with the soldering iron.
> Then, the solder can be removed with solder wick and the new chip
installed.
> 


If all else fails I may go with this. I don't mind if the chip is damaged
during removal as I have replacements.

Thanks

Rob

> For through hole chips, the safest way is to snip the pins off at the chip
body
> with tiny diagonal cutters, remove the body and then pick each lead out
with
> tweezers while heating the pad with the soldering iron.  Also, with good
> desoldering tools, you can remove the chip without destroying it.  The
best
> desolderers have a vacuum pump (or air venturi pump) and a hollow
> desoldering tip.  You apply the tip to the lead for about 5 seconds, then
apply
> the vacuum while "swirling" the tip around the component lead.
> This works amazingly well, and the parts generally fall off the board when
all
> leads are done, even on multi-layer boards.  The solder suckers that are
used
> with a standard iron are FAR inferior to the units described above.
> 
> Jon

RE: ChipQuik Troubles

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Chuck Guzis
> via cctalk
> Sent: 05 July 2017 23:18
> To: cctalk@classiccmp.org
> Subject: Re: ChipQuik Troubles
> 
> On 07/05/2017 01:42 PM, Rob Jarratt via cctalk wrote:
> > I bought some ChipQuik recently and managed to successfully remove a
> > 74LS125 with little trouble. Today I have come to trying to desolder
> > another similar sized chip, but try as I might I just cannot get it to
> > work. The ChipQuik just balls up and won't "take" to the pins. I
> > applied plenty of the flux supplied with the ChipQuik, but I wonder if I 
> > applied
> too much?
> 
> Will the pins take "regular" solder?  I wonder if there might not be some
> coating on them...
> 
> Can't say that I ever had the problem.
> 


I did try to refresh the solder on one pin as I suspected a poor contact, but 
that would not work either. The chip is on the same board that I had success 
with before, but in a different location and where there has been battery 
leakage. I will try a PCB cleaner first to see if there is any residue.

Regards

Rob

Re: ChipQuik Troubles

[Jon Elson via cctalk]

On 07/05/2017 03:42 PM, Rob Jarratt via cctalk wrote:

I bought some ChipQuik recently and managed to successfully remove a 74LS125
with little trouble. Today I have come to trying to desolder another similar
sized chip, but try as I might I just cannot get it to work. The ChipQuik
just balls up and won't "take" to the pins. I applied plenty of the flux
supplied with the ChipQuik, but I wonder if I applied too much?

  



The solders may be incompatible.  What are you trying to do, 
replace a defective chip to make an old board work?


You DON'T need ChipQuik.  If the board was soldered with 
lead-free solder, diluting the solder with PbSn solder makes 
it easier.  If it is already done with leaded solder, then 
you just need a little technique.  For surface mount parts, 
use an Xacto knife under the pins, and lift them one at a 
time while touching with the iron. Generally, I remove as 
much solder as I can with solder wick first, then lift the 
pins.  When one row of pins are lifted, the chip can be 
flexed a few times and the other row of pins break off.  The 
remaining pins can be swept off with the soldering iron.  
Then, the solder can be removed with solder wick and the new 
chip installed.


For through hole chips, the safest way is to snip the pins 
off at the chip body with tiny diagonal cutters, remove the 
body and then pick each lead out with tweezers while heating 
the pad with the soldering iron.  Also, with good 
desoldering tools, you can remove the chip without 
destroying it.  The best desolderers have a vacuum pump (or 
air venturi pump) and a hollow desoldering tip.  You apply 
the tip to the lead for about 5 seconds, then apply the 
vacuum while "swirling" the tip around the component lead.  
This works amazingly well, and the parts generally fall off 
the board when all leads are done, even on multi-layer 
boards.  The solder suckers that are used with a standard 
iron are FAR inferior to the units described above.


Jon

Re: ChipQuik Troubles

[Chuck Guzis via cctalk]

On 07/05/2017 01:42 PM, Rob Jarratt via cctalk wrote:
> I bought some ChipQuik recently and managed to successfully remove a 74LS125
> with little trouble. Today I have come to trying to desolder another similar
> sized chip, but try as I might I just cannot get it to work. The ChipQuik
> just balls up and won't "take" to the pins. I applied plenty of the flux
> supplied with the ChipQuik, but I wonder if I applied too much?

Will the pins take "regular" solder?  I wonder if there might not be
some coating on them...

Can't say that I ever had the problem.

--Chuck

Re: ChipQuik Troubles

[Chris Pye via cctalk]

> On 6 Jul 2017, at 6:42 am, Rob Jarratt via cctalk  
> wrote:
> 
> I bought some ChipQuik recently and managed to successfully remove a 74LS125
> with little trouble. Today I have come to trying to desolder another similar
> sized chip, but try as I might I just cannot get it to work. The ChipQuik
> just balls up and won't "take" to the pins. I applied plenty of the flux
> supplied with the ChipQuik, but I wonder if I applied too much?

Hi Rob, is there a chance that the second chip is on a lead free board?
Sometimes it helps to flow a bit of normal lead/tin solder on the pins first.

Chris..