De Solder SM electrolytic caps

[RubbishRat]

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.


--
Just add a little Rub to email me :^)

 

On Thu, 01 Apr 2010 17:10:48 -0500, RubbishRat
<bishrat@hotmail.com>wrote:

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.

Snap it in half and remove each end with micro soldering iron?

 

[Jeffrey D Angus]

RubbishRat wrote:

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.

Two small soldering irons. The poor man's SM tweezers.

Jeff


--
“Egotism is the anesthetic that dulls the pain of stupidity.”
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com

 

On Thu, 01 Apr 2010 17:32:53 -0500, Jeffrey D Angus
<jangus@suddenlink.net>wrote:

RubbishRat wrote:
Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.



Two small soldering irons. The poor man's SM tweezers.

Jeff

Or an SMT tweezer iron tip. Just a couple bucks from digikey

 

[Martin Crossley]

Meat Plow wrote:

On Thu, 01 Apr 2010 17:32:53 -0500, Jeffrey D Angus
jangus@suddenlink.net>wrote:

RubbishRat wrote:
Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of
the flimsy little pads off with it. Also would it be OK to replace
a SM cap with a similar value radial if I support the radial with a
blob of silicon sealer or something after soldering ?
Any help welcomed.



Two small soldering irons. The poor man's SM tweezers.

Jeff

Or an SMT tweezer iron tip. Just a couple bucks from digikey

Sometimes the glue securing the pads to the PCB is strong enough to allow a
solder blob on each lead huge enough for the second to remain molten while
the first is re-heated and the capacitor quickly, but gently, lifted off.
If there's a hiss or a fishy smell, the leaked electrolyte definitely needs
cleaning off with an ionic solvent and any nearby tracks inspecting.

 

On Fri, 2 Apr 2010 00:37:38 +0100, "Martin Crossley"
<Martin@g8uwm.NOSPAMabelgratis.net>wrote:

Meat Plow wrote:
On Thu, 01 Apr 2010 17:32:53 -0500, Jeffrey D Angus
jangus@suddenlink.net>wrote:

RubbishRat wrote:
Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of
the flimsy little pads off with it. Also would it be OK to replace
a SM cap with a similar value radial if I support the radial with a
blob of silicon sealer or something after soldering ?
Any help welcomed.



Two small soldering irons. The poor man's SM tweezers.

Jeff

Or an SMT tweezer iron tip. Just a couple bucks from digikey

Sometimes the glue securing the pads to the PCB is strong enough to allow a
solder blob on each lead huge enough for the second to remain molten while
the first is re-heated and the capacitor quickly, but gently, lifted off.
If there's a hiss or a fishy smell, the leaked electrolyte definitely needs
cleaning off with an ionic solvent and any nearby tracks inspecting.

I've done that but first used a Dremel to saw the cap in half then
remove. Then an 80 watt tweezers tip iron and a jeweler's screwdriver.
I used to work on hand held transceivers that were nothing but SMD and
got some good practice.

 

[Arfa Daily]

"RubbishRat" <bishrat@hotmail.com> wrote in message
news:Xns9D4DEBCBB186Cbishrathotmailcom@216.196.109.145...

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.


--

You would think that it would be ok to sub a regular electrolytic for a s.m.
one, but in my experience, it seldom seems to work, and I've never really
figured out why, except that the ESR of s.m. caps seems to usually be
considerably higher than that of the same value cap in a conventional wire
ended package. Maybe the designers have to take this into account ? A
classic example is the three little 47uF s.m. electros that you find on the
servo board under some Sony CD mechs. These caps have a habit of leaking,
and causing poor 'playability', but if you try replacing them with
conventional electros, the servos barely work, if at all. Replace them with
original surface mount types, and the performance is returned to
'ex-factory'.

As for getting the little muthas off the board, I tend to flood the pads
with new solder first (always nice low melting point leaded, even if the
board is constructed in lead-free), and then heat one side and lift gently
with a scalpel tip, and then repeat for the other end. In stubborn cases,
like others have suggested, I use two irons, with their temperatures cranked
well up ...

Arfa

 

[Jim Yanik]

Jeffrey D Angus <jangus@suddenlink.net> wrote in
news:hp36up01f6t@news5.newsguy.com:

RubbishRat wrote:
Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of
the flimsy little pads off with it.

solderwick is noted for removing SMD pads;
you have to apply too much heat to get the wick hot enough to wick up
solder.

Also would it be OK to replace a
SM cap with a similar value radial if I support the radial with a
blob of silicon sealer or something after soldering ?
Any help welcomed.



Two small soldering irons. The poor man's SM tweezers.

Jeff

get a soldering iron that will accept a 6/32 screw where the tip
belongs,then cut and form some thickwall copper tubing into an L shape,with
a notch on one side that fits the SMD you're trying to unsolder.
then drill a hole for the 6/32 screw on the other side of the L.
you've just made a custom SMD desoldering tip for caps or resistors.
you'll need several different sizes.

--
Jim Yanik
jyanik
at
localnet
dot com

 

[JW]

On Thu, 01 Apr 2010 17:10:48 -0500 RubbishRat <bishrat@hotmail.com> wrote
in Message id: <Xns9D4DEBCBB186Cbishrathotmailcom@216.196.109.145>:

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.

I routinely re-cap Tektronix acquisition boards from TDS series scopes.
I've found the best way is to cut them close to the board - right where
the can dimples in a bit. Then I just flick the remaining part of the can
and plastic off with an x-acto knife, and remove each leg with a soldering
iron. There's about 70 in each scope, and I've probably done 50 scopes in
all. Never damaged a single pad.

 

[Tim Schwartz]

On 4/1/2010 6:10 PM, RubbishRat wrote:

Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of the
flimsy little pads off with it. Also would it be OK to replace a SM cap
with a similar value radial if I support the radial with a blob of silicon
sealer or something after soldering ?
Any help welcomed.


Well,

Here is an odd possibility. One brand of stereo I service has a mod
that require removing 16 SM caps from a PC board. (That's the entire
mod). In speaking with a friend who also services these, he suggested
grabbing the cap with a pair of needle nose pliers and rotating the cap
until the leads snap. This usually requires about 90 degrees of
rotation. Then it's easy to clean up the pads. The caps are 10uf/16V and
have a black plastic base.

I'D SUGGEST TRYING THIS NO A SCRAP BOARD FIRST, as some boards may not
have the foil attached as well as these.

Regards,
Tim Schwartz
Bristol Electronics

 

[Jim Yanik]

Tim Schwartz <tim@bristolnj.com> wrote in
news:4BB71FDB.8010408@bristolnj.com:

On 4/1/2010 6:10 PM, RubbishRat wrote:
Hi,
Does anyone have any good tips for desoldreing these SM caps without
damaging the pads?
I tried wicking each pad dry but the darned thing still took one of
the flimsy little pads off with it. Also would it be OK to replace a
SM cap with a similar value radial if I support the radial with a
blob of silicon sealer or something after soldering ?
Any help welcomed.


Well,

Here is an odd possibility. One brand of stereo I service has a
mod
that require removing 16 SM caps from a PC board. (That's the entire
mod). In speaking with a friend who also services these, he suggested
grabbing the cap with a pair of needle nose pliers and rotating the
cap until the leads snap. This usually requires about 90 degrees of
rotation. Then it's easy to clean up the pads. The caps are 10uf/16V
and have a black plastic base.

I'D SUGGEST TRYING THIS NO A SCRAP BOARD FIRST, as some boards
may not
have the foil attached as well as these.

Regards,
Tim Schwartz
Bristol Electronics

SM caps don't have "leads". SM = surface mount.
Just get or make the right tool for the job.

--
Jim Yanik
jyanik
at
localnet
dot com