de-soldering IC's

[Dave]

First off, I haven't done much work with IC's. Last night I wanted to
replace a 20-pin DIP IC. I read various news posts on the subject, bought
myself a desoldering vacuum pump (hand operated squeeze-bulb type), replaced
my aging desoldering braid (good brand, got from digi-key on good advice).

So I heat up my iron, apply the braid, ZOOP, up comes the solder into the
braid. HEY, I says to myself, this ain't so hard. Repeat on the other 19
pins. Let things cool down for a minute or so, try to jiggle the IC loose.
Uh-uh. No way. Ain't gonna' budge. There seemed to be enough residual
solder on the pins to keep them from loosening.

To make a long story short, I used brute force to remove the body of the IC
and heated and removed the pins one by one with a pair of tweezers. The I
heated each hole and shoved a 22ga wire through to clean out the solder.
All the time I was doing this I kept thinking "I am pretty sure the guy at
my local electronics shop does not do this". So, the story has a happy
ending, the new IC is installed.

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Thanks

Dave

 

[GregS]

First off, I haven't done much work with IC's. Last night I wanted to
replace a 20-pin DIP IC. I read various news posts on the subject, bought
myself a desoldering vacuum pump (hand operated squeeze-bulb type), replaced
my aging desoldering braid (good brand, got from digi-key on good advice).

So I heat up my iron, apply the braid, ZOOP, up comes the solder into the
braid. HEY, I says to myself, this ain't so hard. Repeat on the other 19
pins. Let things cool down for a minute or so, try to jiggle the IC loose.
Uh-uh. No way. Ain't gonna' budge. There seemed to be enough residual
solder on the pins to keep them from loosening.

To make a long story short, I used brute force to remove the body of the IC
and heated and removed the pins one by one with a pair of tweezers. The I
heated each hole and shoved a 22ga wire through to clean out the solder.
All the time I was doing this I kept thinking "I am pretty sure the guy at
my local electronics shop does not do this". So, the story has a happy
ending, the new IC is installed.

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Always cut the pins and remove the plastic. Then go about desoldering.

greg

 

[Dave Plowman (News)]

What is the proper method for removing an IC? Should the solder braid
have taken up enough solder to remove the chip? Am I using it wrong?

Snip all the pins and remove them one by one is the best way to avoid PCB
damage.

 

[Ken]

First off, I haven't done much work with IC's. Last night I wanted to
replace a 20-pin DIP IC. I read various news posts on the subject, bought
myself a desoldering vacuum pump (hand operated squeeze-bulb type), replaced
my aging desoldering braid (good brand, got from digi-key on good advice).

So I heat up my iron, apply the braid, ZOOP, up comes the solder into the
braid. HEY, I says to myself, this ain't so hard. Repeat on the other 19
pins. Let things cool down for a minute or so, try to jiggle the IC loose.
Uh-uh. No way. Ain't gonna' budge. There seemed to be enough residual
solder on the pins to keep them from loosening.

To make a long story short, I used brute force to remove the body of the IC
and heated and removed the pins one by one with a pair of tweezers. The I
heated each hole and shoved a 22ga wire through to clean out the solder.
All the time I was doing this I kept thinking "I am pretty sure the guy at
my local electronics shop does not do this". So, the story has a happy
ending, the new IC is installed.

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Thanks

Dave

As others have said, if the IC is not to be saved, cut the pins at the
substrate with diagonal cutters and remove each pin one at a time. The
only thing I would add is to use a solder sucker such as at:
http://www.specialized.net/ecommerce/shop/layout.asp?product_id=038X017

A cautionary note: Desoldering PWBs requires a degree of skill.
Practice on scrap boards before attempting it on something you do not
want to damage. It will prove to be a wise investment of your time.

 

[hot tips]

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Thanks

Dave

Like they say, snipping the pins first makes it a lot easier.

The solder braid should wick out your holes better than sticking wires
through them. You sometimes need to put a little solder on the braid
to get your heat flow happening (just like your iron tip). Remember
the solder is wicking towards the heat so you can run it up by moving
the soldering iron ahead of it. Practice on junk.

The best solder suckers (besides braid) are the spring loaded push rod
types. they'll usually clear out the clipped pin and most of the
solder, leaving just a little clean up for the braid. Avoid the
plastic versions and get the metal body ones. Keep them clean.

There are some specialized solder tips for weller soldering irons that
will unsolder a row of connections at a time, but that's more for high
volume work.

We used to have one of the vacuum unsoldering stations, but from what
I've seen, the user has to spend a lot of time keeping it clean and
unclogged, another high volume kind of thing.

There's lots of tricks, but the best tool is patience.

 

[Arfa Daily]

Like they say, snipping the pins first makes it a lot easier.

The solder braid should wick out your holes better than sticking wires
through them. You sometimes need to put a little solder on the braid
to get your heat flow happening (just like your iron tip). Remember
the solder is wicking towards the heat so you can run it up by moving
the soldering iron ahead of it. Practice on junk.

The best solder suckers (besides braid) are the spring loaded push rod
types. they'll usually clear out the clipped pin and most of the
solder, leaving just a little clean up for the braid. Avoid the
plastic versions and get the metal body ones. Keep them clean.

There are some specialized solder tips for weller soldering irons that
will unsolder a row of connections at a time, but that's more for high
volume work.

We used to have one of the vacuum unsoldering stations, but from what
I've seen, the user has to spend a lot of time keeping it clean and
unclogged, another high volume kind of thing.

There's lots of tricks, but the best tool is patience.

As all the others have said, cut the pins and then take out one at a time.
This is especially true if the board is double sided, or has thru' plated
holes, or internal ground / power planes. However, if you want to save the
IC, you can usually do it with a sucker and braid, on a single sided board
at least, but the trick is, before trying to unsolder the pins, heat each
one, and add new solder first. It's a fact that new solder works and flows
better than old. That said, though, if the board is recent, and manufactured
using lead-free solder, you will struggle, no matter what desoldering aids
you use.

Arfa

 

[n cook]

First off, I haven't done much work with IC's. Last night I wanted to
replace a 20-pin DIP IC. I read various news posts on the subject, bought
myself a desoldering vacuum pump (hand operated squeeze-bulb type), replaced
my aging desoldering braid (good brand, got from digi-key on good advice).

So I heat up my iron, apply the braid, ZOOP, up comes the solder into the
braid. HEY, I says to myself, this ain't so hard. Repeat on the other 19
pins. Let things cool down for a minute or so, try to jiggle the IC loose.
Uh-uh. No way. Ain't gonna' budge. There seemed to be enough residual
solder on the pins to keep them from loosening.

To make a long story short, I used brute force to remove the body of the IC
and heated and removed the pins one by one with a pair of tweezers. The I
heated each hole and shoved a 22ga wire through to clean out the solder.
All the time I was doing this I kept thinking "I am pretty sure the guy at
my local electronics shop does not do this". So, the story has a happy
ending, the new IC is installed.

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Thanks

Dave

I've used this technique for about 20 years and although I have a proper
vacuum assist de-solder station I rarely use it, prefering the following.

De-soldering ICs
Use a hot-air paint-stripper,1400W,500 degree centigrade,with 2 level heat
control to prolong element life. Activity may appear fearsome but it is no
worse than a flow-solder bath.Pre-heat for one minute then apply to
pcb,make
extractor tool to pull ic from component side. Make an IC extractor from an
old large pair,10 inch, of
circlip pliers,the jaws need to open out enough to clip around the ends of
up to 64 pin
ICs with enough force to overcome the mechanical force of the situation
where all
the pins are angled relative to the PCB holes.Forge around both of the
original circlip
pins,one joggle at right angle to clear the heigth of the ICs and a slight
inwards joggle
to make purchase on the underside of the IC,grinding a wedge angle to the
points
helps particularly where there is no clearance between IC and pcb.
Use this technique for salvaging (working order) up to 64 pin ics ( when
practised ),other
components, sm and even repair (tracks are not dislodged).For repair work
beware of
spatter of molten solder causing solder bridges on adjascent compoents
because if you
are doing the job properly,ie not dislodging pcb tracks the IC must be
pulled out with
some force and the board tends to flex so possibility of flicking solder.
The secret is to be as quick as possible,idealy the body of the extracted ic
will
be just about handleable rather than too hot to touch.Try practising on a
board
with close packed TTL chips or similar and aim for an extraction rate of
something like one every 2 seconds.Between boards keep the hot air gun
running on
low power setting (not switching off).Don't rest the gun against the board
when heating
as vibration seems to affect the element life also don't allow the board to
flex back onto the gun for the same reason.Hold the gun so airflow is angled
to the board
as solder spat directly into the nozzle can kill the element.
About the only components that cannot be removed with this technique are
parts
moulded in soft plastic,e.g. crystal sockets,rf coils with plastic former
(IF coils usually OK)
some DIP switches. Even these are desolderable intact if the body of the
component is previously cooled with a blast of aerosol freezer spray.

SAFETY NOTE:- ensure good ventilation, use safety goggles because trapped
water etc in the capaillary structure of glass fibre reinfiorced PCB can
super-
heat to steam and jet out molten solder,also it is possible to overlook
small
electrolytic capacitors on the solder side of the board which of coarse
explode
with the direct heat of the hot air gun and beware of very
slight risk of combustion of adjascent flammable parts especially where
components have extra (un-noticed) mechanical bonding leading to extended
duration of heating activity.

 

[Dave]

It seems that gravity is working against me... I am putting the solder braid
on top, and it isn't drawing the solder up and out of the hole. I guess I
can try it from the bottom.

As all the others have said, cut the pins and then take out one at a time.
This is especially true if the board is double sided, or has thru' plated
holes, or internal ground / power planes. However, if you want to save the
IC, you can usually do it with a sucker and braid, on a single sided board
at least, but the trick is, before trying to unsolder the pins, heat each
one, and add new solder first. It's a fact that new solder works and flows
better than old. That said, though, if the board is recent, and manufactured
using lead-free solder, you will struggle, no matter what desoldering aids
you use.

The board is at least 5 years old. The solder seems to take quite a bit of
heat to melt, I don't know if that would indicate lead-free. I've done a
bit of desoldering of things like capacitors, transistors, etc. and have not
run into this type of problem. I was ready to chuck the whole mess in the
trash after 2 hours last night... I am going to try adding new solder next
time

When using the desoldering pump, do you heat one side of the board and apply
the pump to the other? My pump has a plastic or teflon tip and I worry
about it melting. I guess I'll try it and see what happens.

 

[Dave]

I've used this technique for about 20 years and although I have a proper
vacuum assist de-solder station I rarely use it, prefering the following.

De-soldering ICs
Use a hot-air paint-stripper,1400W,500 degree centigrade,with 2 level heat
control to prolong element life. Activity may appear fearsome but it is no
worse than a flow-solder bath.Pre-heat for one minute then apply to
pcb,make
extractor tool to pull ic from component side.

This is the best idea I've heard since someone suggested solder reflow using
the toaster oven (which, btw, I haven't tried yet). I have a heat gun
someplace, will check the rating on it and see if it will work.

Dave

 

[Arfa Daily]

It seems that gravity is working against me... I am putting the solder
braid
on top, and it isn't drawing the solder up and out of the hole. I guess I
can try it from the bottom.


The board is at least 5 years old. The solder seems to take quite a bit
of
heat to melt, I don't know if that would indicate lead-free. I've done a
bit of desoldering of things like capacitors, transistors, etc. and have
not
run into this type of problem. I was ready to chuck the whole mess in the
trash after 2 hours last night... I am going to try adding new solder
next
time

When using the desoldering pump, do you heat one side of the board and
apply
the pump to the other? My pump has a plastic or teflon tip and I worry
about it melting. I guess I'll try it and see what happens.

If the board is 5 years old, it is unlikely that it has been manufactured
using lead-free solder. I think you will find that it's just that the solder
has chemically aged, and also formed an oxide layer on its surface, which
can be quite hard, and a good heat insulator. New solder added before
unsoldering is definitely the order of the day, in these cases.

The tip on the solder sucker will melt - but only after it's unsoldered like
500 joints. Put the iron on the side of the joint. Add some new solder. Let
it all cook for 2-3 seconds, then push the tip of the sucker firmly against
the other side of the joint, into the molten solder, whilst still holding
the iron tip, exactly where it was. When you release the sucker, it will
take the old solder off clean. Some people prefer to place the nozzle over
the end of the wire or pin. This is fine also, but don't push the nozzle all
the way down to the board, and don't remove the iron tip from the joint.
Just lean the nozzle over, away from the iron tip. I prefer the former
method as, if the component leg that you're sucking is large, it can block
the nozzle to the point where there is not enough space around it for the
solder to be sucked off the joint.

Arfa

 

[Smitty Two]

First off, I haven't done much work with IC's. Last night I wanted to
replace a 20-pin DIP IC. I read various news posts on the subject, bought
myself a desoldering vacuum pump (hand operated squeeze-bulb type), replaced
my aging desoldering braid (good brand, got from digi-key on good advice).

So I heat up my iron, apply the braid, ZOOP, up comes the solder into the
braid. HEY, I says to myself, this ain't so hard. Repeat on the other 19
pins. Let things cool down for a minute or so, try to jiggle the IC loose.
Uh-uh. No way. Ain't gonna' budge. There seemed to be enough residual
solder on the pins to keep them from loosening.

To make a long story short, I used brute force to remove the body of the IC
and heated and removed the pins one by one with a pair of tweezers. The I
heated each hole and shoved a 22ga wire through to clean out the solder.
All the time I was doing this I kept thinking "I am pretty sure the guy at
my local electronics shop does not do this". So, the story has a happy
ending, the new IC is installed.

What is the proper method for removing an IC? Should the solder braid have
taken up enough solder to remove the chip? Am I using it wrong?

Thanks

Dave

Uh oh, here comes the liquid flux nut again:


Get some liquid flux !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Really !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


I never solder without it, and you should never, ever, ever, try to
desolder without it, unless irritation and frustration and destroyed
parts and boards are interesting to you.

METHOD 1: (preferred)

Get a multi-hundred dollar desoldering machine. Put liquid flux on the
top and the bottom of each pin. Let the desoldering machine heat up for
ten minutes, minimum, before using it. Use a NEW, correctly sized
nozzle! (0.10" min, 0.13" max)

One pin at a time:

1) Heat pin for five full seconds, watching the TOP side of the board
to make sure the solder melts all the way through. Do not press hard on
the board, just contact it, to avoid damaging or lifting the pad.

2) Circle the tip around as much as the IC pin poking into it will
allow. Think of a hula hoop. Use a bit of tweaking action to pull the
pin, if flared out, into center of hole.

3) NOW pull the trigger, and continue circling, for two seconds.

Note that if you don't melt all the solder before pulling the trigger,
you have to start over. By starting over, I mean, adding more liquid
flux, and resoldering the pin with more solder. Then more flux, and try
again. Watch the topside. Pins that connect to ground plane topside take
the longest, but you MUST wait until you see all the solder flowing
before you hit that trigger!

Repeat on other pins. The IC will come out without the slightest fuss,
intact, reusable if was good to start with, and the board completely
undamaged.


----------------------------

ALTERNATE method for those who can't justify owning a professional
sucker:

Cut the pins, as others suggested. Now, get out your liquid flux. You do
have some, right? You say you solder, and you don't have liquid flux?
That's absurd. Go get some.

Put flux on the top and bottom of each pin.

Now, hold the board over the edge of the table with one hand, so that
both the top of the board and the part of the hand used for karate chops
face down to the table.

Melt the solder for at least three seconds. The pin will usually fall
out by then, but regardless of whether or not it falls, pull the
soldering iron away and *immediately* karate chop that table! This
hurts some, but the reward is worth it.

The pin, if it was still there, and the solder, will depart the board,
leaving a nice, clean, wide open hole. And a nice solder splash on your
table. Repeat as needed. After fourteen to sixteen pins, your hand may
hurt some, but your heart will sing. You must be courageous! Do not
soften up as you go along! Stay vigorous.

Now go get some liquid flux before you embarrass yourself.

 

[n cook]

This is the best idea I've heard since someone suggested solder reflow using
the toaster oven (which, btw, I haven't tried yet). I have a heat gun
someplace, will check the rating on it and see if it will work.

Dave

You definitely need a tool to pull the IC off the board as soon as the
solder is non-solid/breaking up ie before even fully melted quite possibly.
An old pair of long nose pliers with the ends ground down so the remnant
tips can be bent inwards to grab the ends of the IC would probably be
sufficient to show the method works.
Also definitely practise on an old/scrap board first as it needs that
confidence because otherwise pointing a glowing hot element and 300 degree C
or so blast of hot air at a pcb is not a natural thing to do.

 

[Dave]

Get some liquid flux !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Really !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


I never solder without it, and you should never, ever, ever, try to
desolder without it, unless irritation and frustration and destroyed
parts and boards are interesting to you.

All right, already. I went and got some godd#mn flux about a year ago after
reading one of your posts. Still not sure exactly when to use it or how
much to use... seems to leave a bit of a mess on my board when the job is
done, i.e. doesn't come off with isopropanol and a Q-tip.

METHOD 1: (preferred)

Nope. No fancy desoldering station for me, one more piece of electronic
gear in my workshop and I'll be in divorce court for sure. I like the $5
desoldering braid. I may learn to like my $15 desoldering pump if I figure
out the technique.

ALTERNATE method for those who can't justify owning a professional
sucker:

Cut the pins, as others suggested. Now, get out your liquid flux. You do
have some, right? You say you solder, and you don't have liquid flux?
That's absurd. Go get some.

Put flux on the top and bottom of each pin.

Now, hold the board over the edge of the table with one hand, so that
both the top of the board and the part of the hand used for karate chops
face down to the table.

Melt the solder for at least three seconds. The pin will usually fall
out by then, but regardless of whether or not it falls, pull the
soldering iron away and *immediately* karate chop that table! This
hurts some, but the reward is worth it.

I'm not 100% sure I understand your technique but hey, it's worth a try. I
generally work at my bench; I may need some sort of protective glove to make
it shake given it weighs >150kg and is lag-bolted into a concrete wall. Or
maybe I could try a card table.

The pin, if it was still there, and the solder, will depart the board,
leaving a nice, clean, wide open hole. And a nice solder splash on your
table. Repeat as needed. After fourteen to sixteen pins, your hand may
hurt some, but your heart will sing. You must be courageous! Do not
soften up as you go along! Stay vigorous.

Now go get some liquid flux before you embarrass yourself.

I used some flux yesterday. It worked. It worked very well. It worked so
well I had to clean up the mess on the other side of my board! Part of my
bungling component removal technique is to destroy at least one metal pad
(metal circle on PCB with no trace attached). If one is trying to solder in
a new component, it's tough to get the solder to flow to the other side of
the board without the metal pad... the solder tends to want accumulate on my
iron instead of flowing onto the heated component lead. Ahh, enter the
flux. I used it on two of my IC pins and yowza! Solder went right through
the hole and dripped off the pin on the other side before I realized it!

Thanks for the advice and the entertaining manner in which it was delivered.

Dave

 

[Smitty Two]

All right, already. I went and got some godd#mn flux about a year ago after
reading one of your posts. Still not sure exactly when to use it or how
much to use... seems to leave a bit of a mess on my board when the job is
done, i.e. doesn't come off with isopropanol and a Q-tip.

You only need a drop. I use a 2 oz. squeeze bottle with a 0.010" ID
needle. A larger diameter needle will make a mess. But, whatever, the
alcohol should clean it up OK. I pay about $30 for 5 gallons of alcohol,
and $4.00 for 1000 cotton swabs, so I don't worry too much about the
cost of using several swabs. We use 99% isopropyl. The drugstore rubbing
alcohol may not be as good.

Nope. No fancy desoldering station for me, one more piece of electronic
gear in my workshop and I'll be in divorce court for sure. I like the $5
desoldering braid. I may learn to like my $15 desoldering pump if I figure
out the technique.


I'm not 100% sure I understand your technique but hey, it's worth a try. I
generally work at my bench; I may need some sort of protective glove to make
it shake given it weighs >150kg and is lag-bolted into a concrete wall. Or
maybe I could try a card table.

You're just trying to knock the pin and the molten solder out of the
hole. Think of whacking the board on the table while the solder is
molten. But, instead of that, which might damage something on the board,
I hold the board firmly in hand and whack my hand on the table. Hand
acts as a shock absorber. (Obviously, if the board in question is still
bolted to the inside of a TV cabinet, this technique isn't applicable.)

It's true that new solder is flux cored, but when you're trying to
desolder, whether with a plunger pump or a machine or braid, the trouble
is, there's no flux left in the soldered joint. Flux is what makes the
solder flow. No flux, no flow. That's why some advocate adding more
solder, but what they're really doing is adding a little fresh flux. Far
better to add what's actually needed, some fresh flux. For the solder
braid enthusiasts, liquid flux will improve your results tenfold at
least.

 

[hot tips]

It seems that gravity is working against me... I am putting the solder braid
on top, and it isn't drawing the solder up and out of the hole. I guess I
can try it from the bottom.

For stubborn holes, cut the end of the solder wick at a
slanted angle to form a sharp point. Stick the pointed end
in the hole. Do use liquid or paste flux and fresh solder
with the wick if it's not working. Usually the issue is your
soldering iron tip needing some fresh solder.

Don't forget to clean up the board with something like
rubbing alcohol and q-tips.

 

[Wilton Itamoto]

If the circuit board has solder pads on both sides then it is very difficult
to remove with the braid method. If the pads are on one side only then you
need to make sure that their is no solder between the pins and the holes.
Hope this helps.