Preventing Pad Lifts

[Rob]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

 

[N Cook]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

I'm only coming at this from repair soldering rather than production and
assuming you are referring to hand soldering.
I would suggest the wrong soldering technique may be being used.

With a conical tip then the very tip on the pad and the bulkier part of the
cone to the, in comparison, more massive pin. More heat to the more
massive/heatsinky part of a joint and the rest tends to take care of itself

 

[GregS]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

Stay under 625 F. I seem to need at least that most of the time. use liquid flux,
and only use higher heat on the larger pads. Cut off any parts before removing,
and use some solder braid.

greg

 

[bz]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

Very dependent upon the type of solder used, and what kind of components and
what type of boards you are working with.

By the way, there are printed circuit board repair kits. Google for them.





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[Ken G.]

In the cheap electronics i dont think you can do much . I work on the
cheaper stuff , basically brand new store returned items such as small
stereos & such .
Sometimes foils lift just by handling the board and pushing or tapping
lightly on parts .
I would say keep your soldering tips in good clean condition and dont
heat anything very long . If you can get hold of the part first and pull
on it while quickly heating the pads the part will pop out then very
quicky use de-solder braid to clear the hole .
Use lower heat irons . High heat can very quickly fry whatever holds the
pads on .

 

[Golf]

I can only tell you from my experience (been there, done that), that
too much heat for too long causes this especially when the iron tip is
in contact with the pad. Heat the component pin first, then slide the
tip to the pad to finish removal of solder. This seems to work best
for me. Good luck.

 

[N Cook]

I can only tell you from my experience (been there, done that), that
too much heat for too long causes this especially when the iron tip is
in contact with the pad. Heat the component pin first, then slide the
tip to the pad to finish removal of solder. This seems to work best
for me. Good luck.

I tend to only heat the pin with the iron and introduce the solder wire
between the soldering iron and the pad so the melting solder,only, heats the
pad.
Unless it is a large ground pad or wide strip rather than a pad, ie
substantial heatsinking.

 

[bz]

[email protected] (Ken G.) wrote in 3237.bay.webtv.net:

In the cheap electronics i dont think you can do much . I work on the
cheaper stuff , basically brand new store returned items such as small
stereos & such .
Sometimes foils lift just by handling the board and pushing or tapping
lightly on parts .
I would say keep your soldering tips in good clean condition and dont
heat anything very long . If you can get hold of the part first and pull
on it while quickly heating the pads the part will pop out then very
quicky use de-solder braid to clear the hole .
Use lower heat irons . High heat can very quickly fry whatever holds the
pads on .

An iron with a built in 'solder sucker' helps a lot.

Radio shack has an el-cheapo with a red rubber bulb that works well, or one
can buy an expensive vacuum equipped desoldering station (with temperature
controlled iron).



--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[Jim Yanik]

[email protected] (Ken G.) wrote in 3237.bay.webtv.net:

In the cheap electronics i dont think you can do much . I work on the
cheaper stuff , basically brand new store returned items such as small
stereos & such .
Sometimes foils lift just by handling the board and pushing or tapping
lightly on parts .
I would say keep your soldering tips in good clean condition and dont
heat anything very long . If you can get hold of the part first and pull
on it while quickly heating the pads the part will pop out then very
quicky use de-solder braid to clear the hole .
Use lower heat irons . High heat can very quickly fry whatever holds the
pads on .

My soldering training said that use of solder braid gets more heat applied
to the PCB for a longer time,making pad lifts occur more.
Same for SoldaPults.
They specified the use of a temp controlled vacuum desoldering iron.

 

[Charles]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

1/ Use some good liquid flux before you heat the joint.
2/ Generally, a temperature controlled iron is best.
3/ Lacking a temperature controlled iron, use an 18-W element with a small
conical tip.
4/ Tin the tip and wipe immediately before desoldering.
5/ Sometimes it pays to add fresh solder to the joint before desoldering ...
seems strange but it really works.
6/ Some boards are so crappy that nothing will prevent the pads from
lifting.

 

[Homer J Simpson]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering

Yes. And everything clean and a good flux.

or lower temperature and working a bit slower?

Never. Speed is the key.

 

[bz]

1/ Use some good liquid flux before you heat the joint.
2/ Generally, a temperature controlled iron is best.
3/ Lacking a temperature controlled iron, use an 18-W element with a
small conical tip.
4/ Tin the tip and wipe immediately before desoldering.
5/ Sometimes it pays to add fresh solder to the joint before desoldering
... seems strange but it really works.

Not strange. The original solder could be 95/5 or 60/40 or 50/50 even.
adding some good eutectic solder will make the old solder melt faster and
stay liquid longer.

6/ Some boards are so crappy that nothing will prevent the pads from
lifting.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[Jim Yanik]

Not strange. The original solder could be 95/5 or 60/40 or 50/50 even.
adding some good eutectic solder will make the old solder melt faster
and stay liquid longer.

For that matter,you could use ChipQuick,and desolder at VERY low temps.
ChipQuick solder melts at 160degF,IIRC,so the combined melt point is
IIRC,<250DegF. You could use a heat gun.

 

[Smitty Two]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quick soldering or lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

I'm going to agree with some of what's been said, and disagree with some
of it. I always solder and desolder everything at 800 deg. F. The faster
you can do it, the less chance of damage. And you can work ten times as
fast at 800 as you can at 600. And I always use liquid flux. Always use
liquid flux. And, make sure to use liquid flux, always. Yes, it's true,
I'm the s.e.r. liquid flux police.

The main reason pads lift, I think, is too much physical pressure. Don't
push down on the board with anything more than the weight of the
handpiece. Too many people think that pushing down on the joint will
make the solder melt faster. Nuts. Just use some liquid flux, and crank
that temp dial all the way up.

Also, with a conical tip, do NOT use the point. It hasn't enough thermal
mass to do anything. Try this. Put your left index finger on the desk in
front of you, pointing straight down into the desk. Now take a sharp
pencil in your right hand. The pencil is the soldering iron. The desk is
the pad. The index finger is the component lead (aka leg.)

Hold the pencil at a shallow angle to the desk, so that one portion of
the tip taper, wood part, not graphite, lays flat on the desk. Now slide
the pencil up against your finger. The point touches neither pad nor
lead, but extends beyond them. Maximum possible heat transfer to pad and
lead, simultaneously.

For wicking, just put the wick between the iron and the solder joint,
but use the same technique, and still use flux. It makes solder melt and
flow.

 

[Homer J Simpson]

The main reason pads lift, I think, is too much physical pressure. Don't
push down on the board with anything more than the weight of the
handpiece.

Yes. You should almost 'paint' the solder on.

 

[Michael A. Terrell]

Not strange. The original solder could be 95/5 or 60/40 or 50/50 even.
adding some good eutectic solder will make the old solder melt faster and
stay liquid longer.

All of the paste solder we used in our reflow ovens was 80/20.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

I'm going to agree with some of what's been said, and disagree with some
of it. I always solder and desolder everything at 800 deg. F. The faster
you can do it, the less chance of damage. And you can work ten times as
fast at 800 as you can at 600. And I always use liquid flux. Always use
liquid flux. And, make sure to use liquid flux, always. Yes, it's true,
I'm the s.e.r. liquid flux police.

The main reason pads lift, I think, is too much physical pressure. Don't
push down on the board with anything more than the weight of the
handpiece. Too many people think that pushing down on the joint will
make the solder melt faster. Nuts. Just use some liquid flux, and crank
that temp dial all the way up.

Also, with a conical tip, do NOT use the point. It hasn't enough thermal
mass to do anything. Try this. Put your left index finger on the desk in
front of you, pointing straight down into the desk. Now take a sharp
pencil in your right hand. The pencil is the soldering iron. The desk is
the pad. The index finger is the component lead (aka leg.)

Hold the pencil at a shallow angle to the desk, so that one portion of
the tip taper, wood part, not graphite, lays flat on the desk. Now slide
the pencil up against your finger. The point touches neither pad nor
lead, but extends beyond them. Maximum possible heat transfer to pad and
lead, simultaneously.

For wicking, just put the wick between the iron and the solder joint,
but use the same technique, and still use flux. It makes solder melt and
flow.

Also, leave a 1/8" to 1/4" of used wick at the end to quickly
transfer the heat into the joint. Put the solid spot on the joint, and
apply the iron. When it stops its capillary action clip it back, and
continue. A small bottle of liquid flux to dip it in, between uses is
also handy if you don't have a squeeze bottle with a large bore
hypodermic needle to dispense the liquid flux.

Now that I have a decent digital camera, I will see about making a
short video to show the techniques I used in manufacturing to rework
boards on the module test line. In four years I only damaged a couple
pads, and most of them were caused by the company's refusal to let me
put the stereo microscope on a bench, instead of a cart.

I could desolder and reuse 144 legged ICs. i agree with the liquid
flux, I prefer Kester industrial RMA flux. i think the last bottle was
type 1544 RMA.

I used 750 to 825 degrees on my three different irons. They were
calibrated every three months, and checked daily for high resistance
between he ground pin and the tip. Anything above three ohms required
the tip to be removed, and the shank cleaned with a soft brass brush to
bring the resistance back down. Once an iron reached three ohms, it
could go quite high and cause ESD damage.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Smitty Two]

i agree with the liquid
flux, I prefer Kester industrial RMA flux. i think the last bottle was
type 1544 RMA.

That's the good shit, Maynard.

 

[[email protected]]

Depending on what type of component you are removing the heat, time
and tools are all important. The general rulle its least amount or
heat in the least amount of time with no downward pressure and lots of
patience, thats what I preach to my students. As with all processes
the tools need to do the work and not be used improperly, which in
soldering means avoid at all cost pressure, soldering should not be
pressure activated. Pressure is what gets us in trouble when using
poor maintained equipment or improper techniques.

For most lead bearing solders, which is most likely what you are
dealing with, you should always start with a temp around 600 f and
modifiy from there. If its lead free you will need to up that
slightly, but not dramatically.

If you just do a lot of repair on the cheaper boards, I would suggest
looking into the circuit repairkits/techniques, some of the kits will
be better than the original when used correctly and again good well
maintianed tips and tools are key.

Anyway thats my 2cents email if you have questions or specifics of the
application you would like help with.

Ruffin Blackard
IPC Instructor
http://www.circuittechnology.com

 

[[email protected]]

What are some good techniques for preventing pad lifts, particularly
on cheaply made modern electronics? Is it better to have high
temperature with quicksolderingor lower temperature and working a
bit slower? A suggested basic temperature setpoint for these types of
boards?

Depending on what type of component you are removing the heat, time
and tools are all important. The general rulle its least amount or
heat in the least amount of time with no downward pressure and lots of
patience, thats what I preach to my students. As with all processes
the tools need to do the work and not be used improperly, which in
soldering means avoid at all cost pressure, soldering should not be
pressure activated. Pressure is what gets us in trouble when using
poor maintained equipment or improper techniques.

For most lead bearing solders, which is most likely what you are
dealing with, you should always start with a temp around 600 f and
modifiy from there. If its lead free you will need to up that
slightly, but not dramatically.

If you just do a lot of repair on the cheaper boards, I would suggest
looking into the circuit repairkits/techniques, some of the kits will
be better than the original when used correctly and again good well
maintianed tips and tools are key.

Anyway thats my 2cents email if you have questions or specifics of the
application you would like help with.

Ruffin Blackard
IPC Instructor
http://www.circuittechnology.com