If the soldered components are of the 0.1 or 0.15 inch pitched type I would
suggest you apply a solder (spring operated piston) sucker instead of
desoldering braid

Frank-

I think it is a good idea to have both in your arsenal. I've used a
spring-piston sucker, as well as a squeeze-bulb sucker and solder wick, and
found that the spring-piston sucker had a rebound that damaged the traces of
the PCB.

If you are trying to recover components from a scrap PCB, the spring-piston
sucker would be most efficient so it would probably be your best choice. If
you do not want to damage the PCB, then perhaps the squeeze-bulb sucker or the
solder wick would be better.

I have used Radio Shack's solder wick since I don't have ready access to
anything better. It works, but I suspect they don't use as much flux in the
braid as they could.

Richard- I suggest you pay close attention to Michael A. Terrell's reply. He
described the way the professional repair people did it where I used to work.

73, Fred, K4DII

On Thu, 25 Dec 2003 23:56:36 GMT, "Michael A. Terrell"
wrote:

Richard wrote:

From your experience, who's solder braid is the best? I want to desolder
some components and I want the braid to soak up the solder "At the drop of a
hat".

I use copper braid dipped in liquid rosin flux (RMA). One tip is to
live about 1/16" of braid with the solder in it when you clip it off.
Then put that part against the joint before applying heat. It can will
conduct heat to the old joint faster, and do less damage. The method is
called "Wet wicking" Keep in mind that wave soldered boards were done
with 80/20 solder so it would cool before leads had a chance to move.
So, you may need to clean the surface of the old solder before removing
it. Apply a thin bead of RMA flux along a row of pins. Put a small
amount of solder on the tip if the iron, and run it down the row to melt
oxidized solder off the surface. Then use the solder wick to remove the
solder. Before I was laid off, I routinely worked with 288 pin surface
mount parts and had to be very careful about lifting pads on $8,000
boards.

After a hole is clear of solder let it cool for a second or two, then
touch the tip of the lead and see if it is free. If it is stuck, let the
lead adsorb heat from the iron till it breaks free of the plated through
hole. Let it go and see that it doesn't stick again. With a little
practice you can do a row ow pins very quickly without damaging the
board. A good soldering iron is a must, and for modern ESD sensitive
parts you need a grounded soldering iron, along with an ES mat and wrist
strap.

If you start doing a lot of through hole work, invest in a vacuum
desoldering station.

Why didn't you just use a Pace station? It seems to me to be rather
risky to use solder wick on surface mount stuff especially with ESD
issues. We are never allowed to use solder wick at work. That said
some of the boards that we do are in excess of 200,000 dollars and are
irreplaceable. These boards are sometimes 8 levels deep and you have
to repair traces that are in the middle of the board. Paces stations
work really well for removing large smd's quickly. Then all you have
to do is run the vacuum over the pads to clean them up.

Tracy

On Thu, 25 Dec 2003 23:56:36 GMT, "Michael A. Terrell"
wrote:

Richard wrote:

From your experience, who's solder braid is the best? I want to desolder
some components and I want the braid to soak up the solder "At the drop of a
hat".

I use copper braid dipped in liquid rosin flux (RMA). One tip is to
live about 1/16" of braid with the solder in it when you clip it off.
Then put that part against the joint before applying heat. It can will
conduct heat to the old joint faster, and do less damage. The method is
called "Wet wicking" Keep in mind that wave soldered boards were done
with 80/20 solder so it would cool before leads had a chance to move.
So, you may need to clean the surface of the old solder before removing
it. Apply a thin bead of RMA flux along a row of pins. Put a small
amount of solder on the tip if the iron, and run it down the row to melt
oxidized solder off the surface. Then use the solder wick to remove the
solder. Before I was laid off, I routinely worked with 288 pin surface
mount parts and had to be very careful about lifting pads on $8,000
boards.

After a hole is clear of solder let it cool for a second or two, then
touch the tip of the lead and see if it is free. If it is stuck, let the
lead adsorb heat from the iron till it breaks free of the plated through
hole. Let it go and see that it doesn't stick again. With a little
practice you can do a row ow pins very quickly without damaging the
board. A good soldering iron is a must, and for modern ESD sensitive
parts you need a grounded soldering iron, along with an ES mat and wrist
strap.

If you start doing a lot of through hole work, invest in a vacuum
desoldering station.

Why didn't you just use a Pace station? It seems to me to be rather
risky to use solder wick on surface mount stuff especially with ESD
issues. We are never allowed to use solder wick at work. That said
some of the boards that we do are in excess of 200,000 dollars and are
irreplaceable. These boards are sometimes 8 levels deep and you have
to repair traces that are in the middle of the board. Paces stations
work really well for removing large smd's quickly. Then all you have
to do is run the vacuum over the pads to clean them up.

Tracy

Tracy Fort wrote:

On Thu, 25 Dec 2003 23:56:36 GMT, "Michael A. Terrell"
wrote:

Richard wrote:

From your experience, who's solder braid is the best? I want to desolder
some components and I want the braid to soak up the solder "At the drop of a
hat".

I use copper braid dipped in liquid rosin flux (RMA). One tip is to
live about 1/16" of braid with the solder in it when you clip it off.
Then put that part against the joint before applying heat. It can will
conduct heat to the old joint faster, and do less damage. The method is
called "Wet wicking" Keep in mind that wave soldered boards were done
with 80/20 solder so it would cool before leads had a chance to move.
So, you may need to clean the surface of the old solder before removing
it. Apply a thin bead of RMA flux along a row of pins. Put a small
amount of solder on the tip if the iron, and run it down the row to melt
oxidized solder off the surface. Then use the solder wick to remove the
solder. Before I was laid off, I routinely worked with 288 pin surface
mount parts and had to be very careful about lifting pads on $8,000
boards.

After a hole is clear of solder let it cool for a second or two, then
touch the tip of the lead and see if it is free. If it is stuck, let the
lead adsorb heat from the iron till it breaks free of the plated through
hole. Let it go and see that it doesn't stick again. With a little
practice you can do a row ow pins very quickly without damaging the
board. A good soldering iron is a must, and for modern ESD sensitive
parts you need a grounded soldering iron, along with an ES mat and wrist
strap.

If you start doing a lot of through hole work, invest in a vacuum
desoldering station.

Why didn't you just use a Pace station? It seems to me to be rather
risky to use solder wick on surface mount stuff especially with ESD
issues. We are never allowed to use solder wick at work. That said
some of the boards that we do are in excess of 200,000 dollars and are
irreplaceable. These boards are sometimes 8 levels deep and you have
to repair traces that are in the middle of the board. Paces stations
work really well for removing large smd's quickly. Then all you have
to do is run the vacuum over the pads to clean them up.

Tracy

These were 17 layer boards that came out of the reflow oven with
severe problems. We received a bad batch of paste solder, and it didn't
show up, till the boards were built. The old solder had to be cleaned up
before they could be removed with the hot air system, and some chips
were damaged in reflow. They developed microscopic cracks on the bottom
that allowed moisture to creep in between the die and the package. By
working under a microscope I could find the damaged parts, clean the
leads enough to have them replaced, and go to the next board. Another
problem was solder balls trapped under the ICs. A little RMA flux, some
2% silver solder and carefully flooding that edge of the chip melted the
stray solder. Then you wicked the edge and resoldered. It takes about
five minutes a side to fix a 288 pin package. If you are good at SMD
work, you can do a better job than a reflow oven.

There are things you will see on a production floor you will never
encounter in the field because you don't get a board till any
manufacturing problems are corrected. I also did preliminary testing on
prototype boards for engineering, qualified new parts and vendors for
purchasing.

I wasn't your average tech. Some people there loved me, others hated
me, because I wasn't afraid to walk into the head of engineering to tell
him there was a problem, and if they couldn't fix it, my next stop was
the president of the company. There were a lot of ECOs and major
redesigns that I pushed through. I also removed several well know
manufacturers from our approved vendor list, because they refused to
correct quality problems. Beckman and Vicor are a couple that come to
mind. Beckman SMD pots were made with defective seals, so they sucked
water inside when the boards were cleaned after reflow. Vicor had a
horrible failure rate on their modular power supplies, and changing the
supply required a chassis redesign to hold the new power supply.

--
Merry Christmas!

Take care, and God bless.
Michael A. Terrell
Central Florida

Tracy Fort wrote:

On Thu, 25 Dec 2003 23:56:36 GMT, "Michael A. Terrell"
wrote:

Richard wrote:

From your experience, who's solder braid is the best? I want to desolder
some components and I want the braid to soak up the solder "At the drop of a
hat".

I use copper braid dipped in liquid rosin flux (RMA). One tip is to
live about 1/16" of braid with the solder in it when you clip it off.
Then put that part against the joint before applying heat. It can will
conduct heat to the old joint faster, and do less damage. The method is
called "Wet wicking" Keep in mind that wave soldered boards were done
with 80/20 solder so it would cool before leads had a chance to move.
So, you may need to clean the surface of the old solder before removing
it. Apply a thin bead of RMA flux along a row of pins. Put a small
amount of solder on the tip if the iron, and run it down the row to melt
oxidized solder off the surface. Then use the solder wick to remove the
solder. Before I was laid off, I routinely worked with 288 pin surface
mount parts and had to be very careful about lifting pads on $8,000
boards.

After a hole is clear of solder let it cool for a second or two, then
touch the tip of the lead and see if it is free. If it is stuck, let the
lead adsorb heat from the iron till it breaks free of the plated through
hole. Let it go and see that it doesn't stick again. With a little
practice you can do a row ow pins very quickly without damaging the
board. A good soldering iron is a must, and for modern ESD sensitive
parts you need a grounded soldering iron, along with an ES mat and wrist
strap.

If you start doing a lot of through hole work, invest in a vacuum
desoldering station.

Why didn't you just use a Pace station? It seems to me to be rather
risky to use solder wick on surface mount stuff especially with ESD
issues. We are never allowed to use solder wick at work. That said
some of the boards that we do are in excess of 200,000 dollars and are
irreplaceable. These boards are sometimes 8 levels deep and you have
to repair traces that are in the middle of the board. Paces stations
work really well for removing large smd's quickly. Then all you have
to do is run the vacuum over the pads to clean them up.

Tracy

These were 17 layer boards that came out of the reflow oven with
severe problems. We received a bad batch of paste solder, and it didn't
show up, till the boards were built. The old solder had to be cleaned up
before they could be removed with the hot air system, and some chips
were damaged in reflow. They developed microscopic cracks on the bottom
that allowed moisture to creep in between the die and the package. By
working under a microscope I could find the damaged parts, clean the
leads enough to have them replaced, and go to the next board. Another
problem was solder balls trapped under the ICs. A little RMA flux, some
2% silver solder and carefully flooding that edge of the chip melted the
stray solder. Then you wicked the edge and resoldered. It takes about
five minutes a side to fix a 288 pin package. If you are good at SMD
work, you can do a better job than a reflow oven.

There are things you will see on a production floor you will never
encounter in the field because you don't get a board till any
manufacturing problems are corrected. I also did preliminary testing on
prototype boards for engineering, qualified new parts and vendors for
purchasing.

I wasn't your average tech. Some people there loved me, others hated
me, because I wasn't afraid to walk into the head of engineering to tell
him there was a problem, and if they couldn't fix it, my next stop was
the president of the company. There were a lot of ECOs and major
redesigns that I pushed through. I also removed several well know
manufacturers from our approved vendor list, because they refused to
correct quality problems. Beckman and Vicor are a couple that come to
mind. Beckman SMD pots were made with defective seals, so they sucked
water inside when the boards were cleaned after reflow. Vicor had a
horrible failure rate on their modular power supplies, and changing the
supply required a chassis redesign to hold the new power supply.

--
Merry Christmas!

Take care, and God bless.
Michael A. Terrell
Central Florida

Rubbing alcohol can be used to remove the excess when you
are through.


Bill & Richard-

Ordinary rubbing alcohol has 70% alcohol and 30% water in it. If you search,
some drug stores carry 90% isopropyl rubbing alcohol.

You may also find a product in the automotive stores that uses alcohol to
remove water from your gas tank and fuel system. An example I found at
Walmart, is "Iso-HEET" water remover that contains isopropyl alcohol as its
main ingredient. It works quite well to remove solder flux, and doesn't seem
to leave any residue of its own.

73, Fred, K4DII

Rubbing alcohol can be used to remove the excess when you
are through.


Bill & Richard-

Ordinary rubbing alcohol has 70% alcohol and 30% water in it. If you search,
some drug stores carry 90% isopropyl rubbing alcohol.

You may also find a product in the automotive stores that uses alcohol to
remove water from your gas tank and fuel system. An example I found at
Walmart, is "Iso-HEET" water remover that contains isopropyl alcohol as its
main ingredient. It works quite well to remove solder flux, and doesn't seem
to leave any residue of its own.

73, Fred, K4DII

On Sun, 28 Dec 2003 01:25:06 -0800, Bill Turner
wrote:

On 27 Dec 2003 19:54:36 GMT, (Fred McKenzie) wrote:

Ordinary rubbing alcohol has 70% alcohol and 30% water in it. If you search,
some drug stores carry 90% isopropyl rubbing alcohol.

This stuff is getting pretty rare, but it would be preferable if you can
find it. I used to see 99% isopropyl alcohol but haven't found any for
years. I keep looking, though.

90% is out there, but as said, tough to find. 99% sounds like
something from an industrial supplier.

As a caveat, one of the chains had a sale on rubbing alcohols a little
ways back, and one of them was 90% ethanol (denatured). However, the
other ingredients included methanol, acetone, and a few other things
which would make it useless for cleaning. I went with the 70% IPA,
because the only other ingredient was water.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

On Sun, 28 Dec 2003 01:25:06 -0800, Bill Turner
wrote:

On 27 Dec 2003 19:54:36 GMT, (Fred McKenzie) wrote:

Ordinary rubbing alcohol has 70% alcohol and 30% water in it. If you search,
some drug stores carry 90% isopropyl rubbing alcohol.

This stuff is getting pretty rare, but it would be preferable if you can
find it. I used to see 99% isopropyl alcohol but haven't found any for
years. I keep looking, though.

90% is out there, but as said, tough to find. 99% sounds like
something from an industrial supplier.

As a caveat, one of the chains had a sale on rubbing alcohols a little
ways back, and one of them was 90% ethanol (denatured). However, the
other ingredients included methanol, acetone, and a few other things
which would make it useless for cleaning. I went with the 70% IPA,
because the only other ingredient was water.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

In article ,
Bill Turner wrote:

On 27 Dec 2003 19:54:36 GMT, (Fred McKenzie) wrote:

Ordinary rubbing alcohol has 70% alcohol and 30% water in it. If you search,
some drug stores carry 90% isopropyl rubbing alcohol.

____________________

This stuff is getting pretty rare, but it would be preferable if you can
find it. I used to see 99% isopropyl alcohol but haven't found any for
years. I keep looking, though.

Rubbing alchohol contains goodies like lanoline or aloe which leaves a
residue. Most of the time it doen't matter, unless, of course you are
looking for high reliability. My local electronics store carries the
electronics grade of isopropanol.

What is weird about the electronics store is that it no longer carries
semiconductors except for LEDs, diodes and selected transistors. They
dropped the line as they said it was not selling and it had a huge
inventory cost. And this outfit is very busy as it sells to installers.
I think their biggest seller is cat-5 cable followed by the hardware
that goes with it. The repairmen have gone the way of the buggy whip
makers.

Al

--
There's never enough time to do it right the first time.......