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'[OT]: Desoldering 16F877'
2001\06\05@113815 by David Dunn

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Anybody have tips on removing a 16F877 from a PCB without destroying the board ? (i don't have one of those expensive
desoldering stations)

I know those spring-loaded plunger types are useless, they will ruin a PCB 99% of the time.

Chem-Wick stuff doesn't pull enough of the solder out of the hole (plated thru)

How about those rubber-bulb things with a soldering iron mounted on I've seen at Radio Shack, do they work worth a
darn ?

http://www.radioshack.com/images/ProductCatalog/ProductImage/64/64-2060.jpg

That thing ^^^^^^^^^^^^^^^

Thanks,

David Dunn

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2001\06\05@114616 by Quentin

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You want to save the PIC?
If not, cut all the pins and use a solder sucker to remove the pins.
Less heat on your board.

Quentin

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2001\06\05@114812 by Spehro Pefhany

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At 09:29 AM 6/5/01 -0500, you wrote:
(sorry double copy..)
>http://www.radioshack.com/images/ProductCatalog/ProductImage/64/64-2060.jpg

Yes, it's better than nothing, particularly for the $15 or so it costs.

Suggest you nip each lead off right by the plastic and then use that RS sucker
to clean out the holes and remove the stubs. You might need a pair of SS
tweezers to remove the bits of leads.

Trying to save the chip would not be a good idea unless you have a nice
Pace desoldering station.

Best regards,

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2001\06\05@121722 by J.Feldhaar

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Hi all,

if you need both the IC and the PCB around it, you may try desoldering using hot
air. For this, you can use a hot air gun, the real good ones are around 300 USD,
but for less than 10 USD you can get a cheap hot air gun at the local hardware
store, like those used for removing paint, etc. I use one of them at home for all
kind of unsoldering, I can get Pentium I sockets out of a multilayer PCB without
damaging the PCB or the socket - but that is dependent on practice, YMMV...
It is cheap, fast and if used with care it doesn't damage other parts, although
very small SMD components tend to get blown away sometimes ;-)

Greets
Jochen Feldhaar
DH6FAZ

Spehro Pefhany schrieb:

{Quote hidden}

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2001\06\05@124059 by Herbert Graf

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I have on of the Rat Shack ones you speak of, it works surprisingly well,
however you have to be very careful with it. Aside from that it isn't very
durable, the tip on mine is actually broken and I can't get it off. :( One
technique that has REALLY worked well is a heat gun, at the right setting
and distance you can simply heat up all the pins at once and the chip just
falls out. Takes ALOT of practice though. TTYL

> {Original Message removed}

2001\06\05@130959 by Kev

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I do a fair amount of "mobile repair" (servicing coin operated games) and a
spring loaded pluger sucker is my best friend.

Replace the tip when it gets deformed, you can lightly lub the plunger &
gasket for better performance.

Use a good soldering iron, pencil point.  Push the leg from one side of the
hole to the other while heating & then suck it clean, go to the next pin.

After doing all the pins, re visit each pin & push it back to the other side
of the hole, this should free it from the hole if you did a good job
removing the solder.

Gently pry up on the chip, pay close attention to the power & ground traces
as these are usually bigger & sink you heat while desoldering (and don't
suck as clean as other pins).

No I don't have 100% success either, once in a blue moon I will pull a
trace, but for $8.00 and a bit of practice it is the best of the cheap
methods for me.

Kev



> Anybody have tips on removing a 16F877 from a PCB without destroying the
board ? (i don't have one of those expensive
> desoldering stations)
>
> I know those spring-loaded plunger types are useless, they will ruin a PCB
99% of the time.

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2001\06\05@142302 by PHYLLIS GUERRA

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KEV, WHAT TYPE OF COIN-OP MACHINES DO YOU WORK ON ?
I WORK FOR AN OPERATOR IN S. IL.

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2001\06\05@160617 by ace do Valle Barros

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Mr. Feldhaar

Is it really efficient?? How can I do it without to destroy the components
around?

> Hi all,
>
> if you need both the IC and the PCB around it, you may try desoldering
using hot
> air. For this, you can use a hot air gun, the real good ones are around
300 USD,
> but for less than 10 USD you can get a cheap hot air gun at the local
hardware
> store, like those used for removing paint, etc. I use one of them at home
for all
> kind of unsoldering, I can get Pentium I sockets out of a multilayer PCB
without
> damaging the PCB or the socket - but that is dependent on practice,
YMMV...
> It is cheap, fast and if used with care it doesn't damage other parts,
although
{Quote hidden}

sucker
> > to clean out the holes and remove the stubs. You might need a pair of SS
> > tweezers to remove the bits of leads.
> >
> > Trying to save the chip would not be a good idea unless you have a nice
> > Pace desoldering station.
> >
> > Best regards,
> >
> >
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
> > Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
> > TakeThisOuTspeffEraseMEspamspam_OUTinterlog.com             Info for manufacturers:
http://www.trexon.com
> > Embedded software/hardware/analog  Info for designers:
http://www.speff.com
> > Contributions invited->The AVR-gcc FAQ is at:
http://www.bluecollarlinux.com
> >
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=
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2001\06\05@163645 by Dale Botkin

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On Tue, 5 Jun 2001, David Dunn wrote:

> Anybody have tips on removing a 16F877 from a PCB without destroying
> the board ? (i don't have one of those expensive desoldering stations)
>
> I know those spring-loaded plunger types are useless, they will ruin a
> PCB 99% of the time.

Not once you develop your technique, assuming you have a decent
solder-sucker.  I have a couple of Solda-Pullits and a Radio Shack one,
they all work OK.

> Chem-Wick stuff doesn't pull enough of the solder out of the hole (plated thru)

Often true.

> How about those rubber-bulb things with a soldering iron mounted on
> I've seen at Radio Shack, do they work worth a darn ?

Oddly, yes.  I have one and it works fine -- again, it takes some
practice.  As with all of the above methods, though, the primary
requirement is PATIENCE and taking care not to just attack it with a 750
degree iron.

Dale
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On my desk I have a workstation...

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2001\06\05@164952 by Dan Michaels

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Dale Botkin wrote:
>On Tue, 5 Jun 2001, David Dunn wrote:
........
>> How about those rubber-bulb things with a soldering iron mounted on
>> I've seen at Radio Shack, do they work worth a darn ?
>
>Oddly, yes.  I have one and it works fine -- again, it takes some
>practice.  As with all of the above methods, though, the primary
>requirement is PATIENCE and taking care not to just attack it with a 750
>degree iron.
>

I have used this type too, and feel it is preferable to the unheated
bulb types. Works best if the sucker endpiece is placed over the
suckee area in such a way as to make a good seal. However, these
jobbers do get quite hot, [and being Radio Shack] the tips tend
to deteriorate too quickly, and the seal suffers. Might help to
use a heat controller [triac, etc].

best regards,
- dan michaels
http://www.oricomtech.com
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2001\06\05@170152 by Dale Botkin

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On Tue, 5 Jun 2001, Dan Michaels wrote:

> Dale Botkin wrote:
> >On Tue, 5 Jun 2001, David Dunn wrote:
> ........
> >> How about those rubber-bulb things with a soldering iron mounted on
> >> I've seen at Radio Shack, do they work worth a darn ?
> >
> >Oddly, yes.  I have one and it works fine -- again, it takes some
> >practice.  As with all of the above methods, though, the primary
> >requirement is PATIENCE and taking care not to just attack it with a 750
> >degree iron.
> >
>
> I have used this type too, and feel it is preferable to the unheated
> bulb types. Works best if the sucker endpiece is placed over the
> suckee area in such a way as to make a good seal. However, these
> jobbers do get quite hot, [and being Radio Shack] the tips tend
> to deteriorate too quickly, and the seal suffers. Might help to
> use a heat controller [triac, etc].

I've been using mine for several years now.  The tip is a little grungy,
and it does get hotter than blazes.  My techinique is to let it get
completely up to temp, then squeeze the bulb, put the tip down over the
pin and "swirl" it in a circular motion to make sure all of the solder
gets melted, and the pin gets unstuck from the side of the hole.  Then
release the bulb, and move to another pin as far away from the one I just
did as possible to try to keep the heat load in any one spot to a minimum.
I sometimes have to hit certain pins a couple of times, and it sometimes
helps to melt a little new solder onto the pin too.  I think the wave
solder machines use a lot harder/hotter solder than I do, my 60/40 rosin
core makes it a lot easier to desolder.

Dale
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2001\06\05@171812 by tims800

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the best way to desolder the ic and save the pcb traces from pulling
from the pcb is a liquid flux or paste made for  electronic work.
the one recommended for wave soldering machines
the kind used for plumbing copper piping is very acidic in nature,
and I do not recommend it. the flux I use is organic in nature (same as the
flux in water based solder 63/37..)
this allows heat around the ic pin and then the solder bulb or solderpullit
device to be used.
although just remember only  8 seconds max is allowed for heat.
alternate the pin sequence 1-3-5..etc.
and then using needle pliers  or pick probe( yuck dentists)
make sure the pin is movable and free before trying to remove
the ic.         this works best for me..

Ps the organic flux is water based so rinse with hot water from sink and
blow dry...sounds simple<G>

{Original Message removed}

2001\06\05@173505 by Ron Wilder

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I agree completely.  I also have a desoldering station, but find the plunger
good enough for most work.
Ron

Kev wrote:

{Quote hidden}

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2001\06\05@181927 by Mark Newland

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Just an option (not one that I use personally)

I forget the name of the metal, but it is used in these disappearing spoon
tricks.  Put the spoon in a cup of hot coffee and watch it melt.  The same metal
is available in solder form also (but more expensive).  You first remove most of
the solder useing wick, solder sucker, etc.  You then put this other metal in the
holes.  You can now heat the whole board at a MUCH lower temperature (via hot air
gun, hot plate, hot coffee??, etc.) and still melt the solder.

{Quote hidden}

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2001\06\05@182951 by Dan Larson

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On Tue, 5 Jun 2001 15:16:31 -0700, Mark Newland wrote:

>Just an option (not one that I use personally)
>
>I forget the name of the metal, but it is used in these disappearing spoon
>tricks.  Put the spoon in a cup of hot coffee and watch it melt.  The same metal
>is available in solder form also (but more expensive).  You first remove most of
>the solder useing wick, solder sucker, etc.  You then put this other metal in the
>holes.  You can now heat the whole board at a MUCH lower temperature (via hot air
>gun, hot plate, hot coffee??, etc.) and still melt the solder.

Bismuth ?



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2001\06\05@192128 by Alexandre Domingos F. Souza

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>I have on of the Rat Shack ones you speak of, it works surprisingly well,
>however you have to be very careful with it. Aside from that it isn't very
>durable, the tip on mine is actually broken and I can't get it off. :( One
>technique that has REALLY worked well is a heat gun, at the right setting
>and distance you can simply heat up all the pins at once and the chip just
>falls out. Takes ALOT of practice though. TTYL

       Another method, that's hard to describe without photos (I'll take some tomorrow, if I remember)

       Build a "dissoldering iron" with a BIG and flat tip, but use a HUGE soldering iron. Something around 150W. So you can heat all the pins of one side of the IC, and after the other side. We use it with another tool, that grabs the IC and helps you to take first the left and after the right side.

       I'll take some photos tomorrow, and put in my page. If someone wants to look, I will post a link to the english instructions.


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2001\06\05@192139 by Alexandre Domingos F. Souza

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>I do a fair amount of "mobile repair" (servicing coin operated games) and a
>spring loaded pluger sucker is my best friend.
>Replace the tip when it gets deformed, you can lightly lub the plunger &
>gasket for better performance.

       In Brazil we use something called "camisinha suga solda" (translation? Something around "solder-sucker condom - believe it or not) that's a little piece of high temperature silicone tubing, put in the tip of the sucker. It helps A LOT to do a better sucking. It's a wide sell product in Brazil and costs mere cents.

>Use a good soldering iron, pencil point.  Push the leg from one side of the
>hole to the other while heating & then suck it clean, go to the next pin.

       Use a Weller!!! These are the best soldering irons your money can buy :o) I use a W60P for years, and only need to replace the tip and the mains wire. BTW, these heating elements are HARD to find here, I have 2 or 3 of these here, waiting for the )@(#%* heating element :oP

>After doing all the pins, re visit each pin & push it back to the other side
>of the hole, this should free it from the hole if you did a good job
>removing the solder.

       Nice to remember too: looking the hole from the botton of the board, you see something like (| ) or ( |) being | the pin of the IC. An easy way to free the pin is using the soldering tip to move the pin to the center of the hole, and sucking the solder. The pin will be isolated from the via. With some pratice, it's easy to do!

>Gently pry up on the chip, pay close attention to the power & ground traces
>as these are usually bigger & sink you heat while desoldering (and don't
>suck as clean as other pins).

       When the good'ld Weller doesn't fit, I use 2 soldering irons in "parallel" hehehe :o)

       But something good to remember too: An easy way to free the IC after all the pins are clean, is to grab the IC with pilers and "shake" it CW and CCW to help free the pins that aren't already free. It warrants you a IC without vias :o)

>No I don't have 100% success either, once in a blue moon I will pull a
>trace, but for $8.00 and a bit of practice it is the best of the cheap
>methods for me.

       Same for me. I service lots of arcade, pinball and computer boards with no need of a profissional sucker (I'd love to have one) station.


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2001\06\05@221330 by goflo

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Wood's metal, IIRC.

regards, Jack

Mark Newland wrote:
>
> Just an option (not one that I use personally)
>
> I forget the name of the metal, but it is used in
> these disappearing spoon tricks

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2001\06\06@093320 by J.Feldhaar

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Hello Wallace,

yes, it is definitely possible, although it takes some practice, in my case I
have been doing this for 15 years. The tempertature can be controlled by the
distance of the hot air gun to the PCB. It is best to try on very old boards
first, and then go on practicing on other boards. Always take time for
complicated work - when I'm only desoldering the parts I am very fast, when I am
repairing a PCB it takes about 20 times as long.....

Greets
Jochen Feldhaar
DH6FAZ (and definitely it is Jochen, not "Mr. Feldhaar"...;-)

Wallace do Valle Barros schrieb:

{Quote hidden}

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2001\06\06@115538 by ace do Valle Barros

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Hi Jochen,

Thanks for your sugestion, I'll try it.

And sorry about "Mr. Feldhaar"... :o)

Greets,

Wallace do Valle Barros.

> Hello Wallace,
>
> yes, it is definitely possible, although it takes some practice, in my
case I
> have been doing this for 15 years. The tempertature can be controlled by
the
> distance of the hot air gun to the PCB. It is best to try on very old
boards
> first, and then go on practicing on other boards. Always take time for
> complicated work - when I'm only desoldering the parts I am very fast,
when I am
{Quote hidden}

components
> > around?
> >
> > > Hi all,
> > >
> > > if you need both the IC and the PCB around it, you may try desoldering
> > using hot
> > > air. For this, you can use a hot air gun, the real good ones are
around
> > 300 USD,
> > > but for less than 10 USD you can get a cheap hot air gun at the local
> > hardware
> > > store, like those used for removing paint, etc. I use one of them at
home
> > for all
> > > kind of unsoldering, I can get Pentium I sockets out of a multilayer
PCB
{Quote hidden}

costs.
> > > >
> > > > Suggest you nip each lead off right by the plastic and then use that
RS
> > sucker
> > > > to clean out the holes and remove the stubs. You might need a pair
of SS
> > > > tweezers to remove the bits of leads.
> > > >
> > > > Trying to save the chip would not be a good idea unless you have a
nice
> > > > Pace desoldering station.
> > > >
> > > > Best regards,
> > > >
> > > >
> >
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > =
> > > > Spehro Pefhany --"it's the network..."            "The Journey is
the
> > reward"
> > > > EraseMEspeffspam@spam@interlog.com             Info for manufacturers:
> > http://www.trexon.com
> > > > Embedded software/hardware/analog  Info for designers:
> > http://www.speff.com
> > > > Contributions invited->The AVR-gcc FAQ is at:
> > http://www.bluecollarlinux.com
> > > >
> >
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
{Quote hidden}

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2001\06\06@120811 by Roger Morella

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I find that a good rework station with the right attachments is worth it's
weight in gold.  Pace has an excellent product for a very reasonable price.
(I think I saw one posted here by a list member for a considereable discount
a few days ago ;)  Seriously, a good desolder station will last a life time
and will result in faster, less frustrating, and more importantly, less
damaging rework.  I place this right under a decent scope on my list of must
haves for my shop.

Roger
{Original Message removed}

2001\06\06@165541 by rottosen

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When I clip out the IC to save the board, I don't use a solder sucker to
remove the pins from the holes.

Instead, I use a hypodermic needle:

First go to your druggist and get a syringe with the biggest needle they
have. The size I always get is just the right size to go snugly through
an IC lead's hole. (Note: In our drug war society you aren't supposed to
be able to do this. I have never had ANY trouble getting a needle, no
questions asked. Maybe it is because I always ask for the biggest needle
they have?).

Remove the needle from the syringe and grind off the sharp tip. Use the
syringe for dispensing fluids, etc.

Place the needle over the IC lead on the solder side of the board. Heat
the pad and the needle until the needle pushes through the board taking
the IC lead with it.

Remove the heat and wiggle/rotate the needle in the hole until the
solder solidifies. The needle is stainless steel and the solder will not
stick to it.

Pull the needle out of the hole. There may be a tube of solder sticking
out from the hole. Just break this off with your finger nail.

The hole is now open and solder free with the pad, plating and trace
100% intact every time!


-- Rich


Quentin wrote:
{Quote hidden}

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2001\06\06@185912 by Alexandre Domingos F. Souza

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>I find that a good rework station with the right attachments is worth it's
>weight in gold.  Pace has an excellent product for a very reasonable price.

       Sure. How much of us has 3 or 4 kg of gold?


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2001\06\06@213749 by Spehro Pefhany

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At 07:58 PM 6/6/01 -0300, you wrote:

>        Sure. How much of us has 3 or 4 kg of gold?

More like 3-4 troy oz. of gold, and if you get a used one, about 0.5 troy oz.

Best regards,


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2001\06\07@010545 by Bala Chandar

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For removal of ICs from boards, your method sounds wonderful, Richard. I
am going to try it today itself!

For this job, I have always used the desoldering pump. It's
time-consuming and not a perfect solution if you want to save both the
part and the board.

Am I right in assuming that the size of the needle should be such that,
its inner diameter is just enough to allow the IC pin inside and its
outer diameter is slightly smaller than that of the hole on the board?

Regards,
Bala


Richard Ottosen wrote:

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2001\06\07@043209 by Roman Black

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face
Very interesting desoldering technique Richard!
Thanks. But this does require cutting all the
legs off the chip first, right?

I also like Alexandre's Brazilian "rubber condom
tubes" that fit to the end of the solder sucker
device. I would like to try these but have not seen
them for sale here.
-Roman



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2001\06\07@050931 by Vasile Surducan

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face
Roman, that rubber condom tube is made from silicone and equiped
any laboratory peristaltic pumps. It's the best non destruction tested
methode. Not applicable to production desoldering where a hot air
thermocontroled device is the best ( 50...600 Celsius degree )

Vasile



On Thu, 7 Jun 2001, Roman Black wrote:

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2001\06\07@125445 by rottosen

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Roman Black wrote:
>
> Very interesting desoldering technique Richard!
> Thanks. But this does require cutting all the
> legs off the chip first, right?


Yes, the chip must be sacrificed for the safety of the PCB. I like to
say that there is one component of an electronic assembly that can not
be replaced. The PCB!

Roman, also see my revised method in my reply to Bala.


-- Rich


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2001\06\07@125451 by rottosen

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Bala:
I checked the needle that I use. Its outer diameter is about .030 inches
which is just about right for most IC hole diameters.

I should have checked my facts better before writing my description of
the procedure. I just assumed that the needle went over the IC pin.

The needle does not go over the pin. That probably explains why I never
have to remove the pin from the needle.

Slightly revised method:

...  Place the needle onto the end of the IC pin on the solder side of
the board. Heat the pad, pin and needle until the needle pushes through
the board taking the IC lead with it. If the pin is bent or sticks out
of the board very far then clip the pin to the height of the solder
first.  ...

I hope helps with any confusion I caused.


-- Rich


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2001\06\07@134932 by Peter L. Peres

picon face
> Bismuth ?

Wood's metal probably. But it would not work unless it is heated to the
solder temperature first so it gets a chance to alloy with the remaining
solder.

Peter

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2001\06\07@134959 by Peter L. Peres

picon face
> Chem-Wick stuff doesn't pull enough of the solder out of the hole
> (plated thru)

Buy some rosin based flux, flux the joints to be desoldered liberally and
use the wick again. It will work. You may have to add some solder to
joints that are partially sucked, then use the wick.

Peter

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2001\06\07@175536 by Bill Westfield

face picon face
   Wood's metal probably. But it would not work unless it is heated to the
   solder temperature first so it gets a chance to alloy with the remaining
   solder.

It can work because the molten (woods metal) essentially DISOLVES the
solder - no normal-solder-melting temperature required.  I've seen
impressive demos at trade shows along these lines, although I believe
they use an indium alloy ($$$) rather than woods metal...

BillW

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2001\06\07@181412 by David VanHorn

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At 12:04 PM 6/6/01 -0400, Roger Morella wrote:
>I find that a good rework station with the right attachments is worth it's
>weight in gold.  Pace has an excellent product for a very reasonable price.
>(I think I saw one posted here by a list member for a considereable discount
>a few days ago ;)  Seriously, a good desolder station will last a life time
>and will result in faster, less frustrating, and more importantly, less
>damaging rework.  I place this right under a decent scope on my list of must
>haves for my shop.

Me too

I use wick as well, but I happened onto a Pace Micro portable at a hamfest,
in mint condition, a couple years ago for $250, and it was money well
spent.  Keep them clean, and they work great.
Mine is located literally right under my scope :)

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2001\06\07@183729 by Alexandre Domingos F. Souza

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>Wood's metal probably. But it would not work unless it is heated to the
>solder temperature first so it gets a chance to alloy with the remaining
>solder.

       For the brazilian ones, what is wood's metal? Certainly not made of wood :o)


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2001\06\07@210421 by Spehro Pefhany

picon face
At 07:37 PM 6/7/01 -0300, you wrote:
>>Wood's metal probably. But it would not work unless it is heated to the
>>solder temperature first so it gets a chance to alloy with the remaining
>>solder.
>
>        For the brazilian ones, what is wood's metal? Certainly not made
of wood :o)

General
Synonyms: Wood's alloy.
Molecular formula: [An alloy with composition approximately 50% bismuth,
25% lead, 12.5% tin and 12.5% cadmium.]
CAS No:
EINECS No:
Physical data
Appearance: silver grey alloy
Melting point: 65.5 C

Toxicology
Harmful by inhalation, in contact with skin and if swallowed. Skin and eye
irritant.

I wouldn't suggest sucking on a  piece of it. ;-)

Best regards,

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2001\06\08@052337 by Roman Black

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The post about using a metal with lower melting point
triggered a memory, and I confirmed it in our catalogue.

WES components in Australia sells a "SMD desoldering kit"
that is simply flux and a low meltpoint solder. It is
about $18 US. You apply the special solder the the pins,
heat it up with a normal iron and then it stays molten for
quite a while and you can unsolder the whole chip. I don't
know ho many chips it would do. Quite possibly it would
be re-usable??

Sounds smart. I'm sure other suppliers must sell the
kits too, looks like an Asian package.
-Roman

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2001\06\08@112318 by Mark Newland

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This is probally the same exact kit that I used in the past. But as
Spehro found out (thanks for the specs Spehro), the melting point is
65.5 C (150 F).  For thru-hole parts, just put the whole board (after
replaceing the old solder with the "woods alloy") in hot water and not
risk burning it with the hot air gun.

Roman Black wrote:

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2001\06\08@190506 by Alexandre Domingos F. Souza

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face
>WES components in Australia sells a "SMD desoldering kit"
>that is simply flux and a low meltpoint solder. It is
>about $18 US. You apply the special solder the the pins,
>heat it up with a normal iron and then it stays molten for
>quite a while and you can unsolder the whole chip. I don't
>know ho many chips it would do. Quite possibly it would
>be re-usable??

       We can find it in Brazil too. But I think it's cheaper...


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2001\06\09@021943 by Peter L. Peres

picon face
Spehro Pefhany wrote:
> Toxicology Harmful by inhalation, in contact with skin and if
> swallowed. Skin and eye irritant.
>
> I wouldn't suggest sucking on a  piece of it. ;-)

Ok, that must be the usual EPA kind of analysys result. Cadmium is best
known from 'gold' colored screws in equipment and batteries. Lead we all
know and love. Tin is tin, and Bismuth is used for non-polluting fishing
weights (instead of lead). Don't waste too many nights shuddering about
this.

I stand corrected wrt melting point.

Peter

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2001\06\09@045721 by Spehro Pefhany

picon face
At 11:15 PM 6/8/01 +0300, you wrote:

>Ok, that must be the usual EPA kind of analysys result.

Here's a full MSDS (Material Safety Data Sheet) for the material,
as required under WHMIS.

http://www.jtbaker.com/msds/w3500.htm

It's not such a bad material, unless you do stupid things with it,
such as heating it way over its melting point and breathing the
fumes, despite all the talk of damaging the reproductive system and
carcinogenic properties.

"The principal inhalation hazard would be the fumes or fine particles
from the alloy when heated much above its melting point. These would be
of indefinite composition, but it may be assumed that the highly
toxic elements lead and cadmium would be present."

You can buy tin/bismuth alloy from Micromark for $15 US/0.33kg.
(MP 280'F, not sure if it works as well as Wood's metal). Wood's
metal (or a very similar alloy) is the same price but melts at
only 160'F.

>Cadmium is best
>known from 'gold' colored screws in equipment and batteries.

Cadmium was the dull silver (not the shiny silver, which is nickle).
It's not used much anymore, you are talking about _chromate_ finish,
which is that yellow. Cadmium plating was mostly a risk if you tried
to weld it and breathed poisonous cadmium vapour.. of course it's
still used in NiCd batteries.

> Lead we all know and love.

And I hope we all wash our hands before eating that Reuben sandwitch,
after soldering, or (especially) handling solder paste. Pregnant women
(or women who might be pregnant) should be especially careful. At some
point fairly soon we'll be saying bye-bye to lead in solders, there is
a lot of movement in that direction. I suspect we'll miss it (for the
soldering characteristics, anyhow).

You're right, our old friend lead is the bad stuff in this material.

>Tin is tin, and Bismuth is used for non-polluting fishing
>weights (instead of lead). Don't waste too many nights shuddering about
>this.

Bismuth is not so bad for a heavy metal (if it's pure), I think mostly
because it's hard to get enough of it absorbed, tin is actually
worse. Bismuth poisoning is a known condition, however.

Best regards,

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