How to resolder a cold solder connection?

[micky]

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board. It seems to have a lot of cold solder problems
after a few years.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh? Thrifty
guy that I am, it never occurred to me that people would routinely do
the seocnd.


He calls it dry solder. Maybe that's the automotive term.

 

[Phil Allison]

"micky"

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

** Yep.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh? Thrifty
guy that I am, it never occurred to me that people would routinely do
the seocnd.

** Wicking ( or using a de-soldering gun) to get the old solder off is
needed to look at the component leads or pins before re-soldering

If the lead looks shiny and tinned all over - fine.

If the lead looks dark and dry of solder - not fine.

Also, there is now the issue of mixing dissimilar solders - ie leaded and
unleaded.

I use Multicore "Savbit" solder for all repairs as it will not absorb
copper, has higher than usual strength and a very good flux core.


..... Phil

 

[Dave Platt]

In article <hsu557hoo1k9d4nlg0tmk2ujh3dtvff5hs@4ax.com>,
micky <NONONOmisc07@bigfoot.com> wrote:

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

I think "it depends".

There may be some advantages to clearing off the old solder and
replacing it entirely. Two possible such:

(1) Some years ago I had a problem with an audio amplifier...
intermittent solder joints. The manufacturer informed me that
their contract assembly house had "use the wrong solder" in the
wave-solder machine, and that this had resulted in a poor joint on
the transistor connections. I'm not sure whether it was a poor
bond due to the alloy used, or whether there was a difference in
thermal expansion rates which caused the joint to suffer more
stress due to power-on-heat/power-off-cold cycling.

The manufactuer specifically recommended that I strip out the old
solder and replace it.

(2) In some cases, the problem with a bad solder joint might be due to
the contact materials being soldered - oxidation, other
contamination, or an alloy which didn't "wet" well with the
solder/flus combination originally used.

In this case, stripping off the old solder, perhaps cleaning or
lightly scraping the metal, applying some proper flux to the
metal, and re-soldering would give you the best chance of a good
solder bond. Simply re-flowing the existing connection would not
necessarily get enough flux into the joint area to address any
problems on the contact surfaces.

Issue (2) might hold, even if the joint was originally OK. If the
solder bond has cracked away from the contact metal, then the metal
surface has had the oppotunity to oxidize... and so getting some good
flus into the contact surface when re-soldering is probably a good
idea.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Jeff Liebermann]

On Mon, 22 Aug 2011 21:06:55 -0400, micky <NONONOmisc07@bigfoot.com>
wrote:

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

Yes. Especially when the old solder is leaded, and the new solder is
un-leaded. If I'm not sure, I clean the joint with a solder sucker
and maybe braid just to be sure.

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board. It seems to have a lot of cold solder problems
after a few years.

RoHS unleaded solder which is not very strong. If you want strength,
use silver solder. My guess is that the engine control board gets
quite a pounding under the hood, and may have top heavy components
trying to flex the leads. If this is a problem, you might get a big
improvement if you can support the top heavy components with RTV,
silicon rubber, or hot melt glue. That will take the load off the
solder connection.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh? Thrifty
guy that I am, it never occurred to me that people would routinely do
the seocnd.

I do both. When I know that I'm using the same type of solder, I just
reheat and add more solder (with flux). If I don't know the solder
type, I remove as much of the old solder as possible.

He calls it dry solder. Maybe that's the automotive term.

I've never heard of that term.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Winston]

micky wrote:

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

Yes. Re-flowing is *possible* but risky, because
it generally results in a oxide-polluted 'cold' joint.

In either event, it is critical to apply separate flux
to the joint to float oxides out during the soldering
process. The improvement in quality is substantial.

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board. It seems to have a lot of cold solder problems
after a few years.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh?

Honestly, I dab flux on the joint and reheat. It is quick
and effective. For joints that appear cold after that operation,
I remove the old solder, re-flux and use good quality leaded
solder. (Then *always* clean with a 50/50 mix of alcohol and naphtha).
That hasn't failed yet.

Thrifty guy that I am, it never occurred to me that people would
routinely do the seocnd.

After your first 10 repairs it goes a lot faster.

He calls it dry solder. Maybe that's the automotive term.

He meant to say:
""Cold" solder joints (a frosted appearance),"

Here is a classic example. Note the frosted
appearance of the solder and the lack of 'wetting'
on the pin:
http://upload.wikimedia.org/wikipedia/commons/a/a0/Cold_solder_joint.jpg

--Winston

 

[Phil Allison]

"micky"

He calls it dry solder.

** In fact he said " Dry solder joint " - a very common term.

The word dry refers to a lack of " wetting " of one or both the metal
surfaces to be soldered.

If an otherwise solderable metal surface is contaminated with oxides or
similar, hot solder will simply refuse to alloy with it and there will be no
or only minimal electrical connection and no mechanical strength.

A frosted appearance on the joint is generally due to movement while
cooling, insufficient heat or the use of lead free solder.


..... Phil

 

[Phil Allison]

<stratus46@yahoo.com>


What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.


** What for ?

Solder flux is normally harmless and routinely left behind by many
manufacturers.



..... Phil

 

[N_Cook]

Winston <Winston@BigBrother.net> wrote in message
news:j2v7jd0hc6@news7.newsguy.com...

micky wrote:
http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

Yes. Re-flowing is *possible* but risky, because
it generally results in a oxide-polluted 'cold' joint.

In either event, it is critical to apply separate flux
to the joint to float oxides out during the soldering
process. The improvement in quality is substantial.

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board. It seems to have a lot of cold solder problems
after a few years.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh?

Honestly, I dab flux on the joint and reheat. It is quick
and effective. For joints that appear cold after that operation,
I remove the old solder, re-flux and use good quality leaded
solder. (Then *always* clean with a 50/50 mix of alcohol and naphtha).
That hasn't failed yet.

Thrifty guy that I am, it never occurred to me that people would
routinely do the seocnd.

After your first 10 repairs it goes a lot faster.

He calls it dry solder. Maybe that's the automotive term.

He meant to say:
""Cold" solder joints (a frosted appearance),"

Here is a classic example. Note the frosted
appearance of the solder and the lack of 'wetting'
on the pin:
http://upload.wikimedia.org/wikipedia/commons/a/a0/Cold_solder_joint.jpg

--Winston

There's me thinking all those decades that cold solder joint meant lack of
sweating, ie lack of wetting (melding) to the metal surface due to lack of
heating

 

On Aug 22, 6:06 pm, micky <NONONOmis...@bigfoot.com> wrote:

http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder     As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board.  It seems to have a lot of cold solder problems
after a few years.

 When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh?   Thrifty
guy that I am, it never occurred to me that people would routinely do
the seocnd.

He calls it dry solder.  Maybe that's the automotive term.

What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.

G˛

 

[Allodoxaphobia]

On Mon, 22 Aug 2011 19:02:51 -0700, Jeff Liebermann wrote:

On Mon, 22 Aug 2011 21:06:55 -0400, micky wrote:

He calls it dry solder. Maybe that's the automotive term.

I've never heard of that term.

I think that is a left-ponder/right-ponder 'distinction'.

 

[Winston]

N_Cook wrote:

(...)

There's me thinking all those decades that cold solder joint meant lack of
sweating, ie lack of wetting (melding) to the metal surface due to lack of
heating

It can.

A poor joint can result from lots of different
things. An overheated joint can also exhibit
'dewetting' because of rapid corrosion growth.

In casual Googling just now, I see some really
misleading information about proper electronic
soldering technique. That's a pity, because each
article I saw contains several good ideas with a
real stinker thrown in.

In one case, the user is cautioned (and I am not
making this up):
"The use of separate acid flux paste (e.g. as used
by plumbers) should NEVER be necessary in normal
electronics applications because electronics-grade
solder already contains the correct grade of flux!"
http://www.epemag.wimborne.co.uk/solderfaq.htm

Well, of course one would never use *acid* flux on
an electrical or electronic joint. One uses a
flux compatible with one's properly selected solder.

In another case, the poor reader is bombarded
with information about 5 different kinds of solder,
3 of which should never be used on electronics.
http://www.elexp.com/t_solder.htm
They go on to imply that added flux is *always*
a bad idea. This is nonsense. Added flux
compatible with your properly selected solder is
*always* a good idea.

http://www.youtube.com/watch?v=I_NU2ruzyc4
This video is difficult to watch for folks that
already know how to do electronic soldering because
it illustrates some really bad technique, initially.

It does go on to illustrate good technique but still
does not emphasize fluxing and joint prep properly IMHO.


--Winston

 

[Winston]

Allodoxaphobia wrote:

On Mon, 22 Aug 2011 19:02:51 -0700, Jeff Liebermann wrote:
On Mon, 22 Aug 2011 21:06:55 -0400, micky wrote:

He calls it dry solder. Maybe that's the automotive term.

I've never heard of that term.

I think that is a left-ponder/right-ponder 'distinction'.

Naaah. I see that 'dry solder joint' is a real term.
It is a variety of 'cold solder' joint with insufficiently
wetted parts.

Avoid 'dry' joints by using careful joint preparation and
fluxing, proper soldering tools and techniques.

--Winston

 

[Jeff Liebermann]

On Tue, 23 Aug 2011 07:12:08 -0700, Winston <Winston@BigBrother.net>
wrote:

Naaah. I see that 'dry solder joint' is a real term.
It is a variety of 'cold solder' joint with insufficiently
wetted parts.

Well, using Google:
<http://www.pcuser.com.au/pcuser/hs2.nsf/lookup+1/2BA1DD3A7AF26E20CA256F2500358412>
and a few others. It seems like it's a real term, but not very
common.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Winston]

Jeff Liebermann wrote:

On Tue, 23 Aug 2011 07:12:08 -0700, Winston<Winston@BigBrother.net
wrote:

Naaah. I see that 'dry solder joint' is a real term.
It is a variety of 'cold solder' joint with insufficiently
wetted parts.

Well, using Google:
http://www.pcuser.com.au/pcuser/hs2.nsf/lookup+1/2BA1DD3A7AF26E20CA256F2500358412
and a few others. It seems like it's a real term, but not very
common.

I agree.
I had to look it up too.

--Winston <--Eschewing kerfuffle; abjuring obfuscation.

 

[Ron]

On 23/08/2011 15:04, Allodoxaphobia wrote:

On Mon, 22 Aug 2011 19:02:51 -0700, Jeff Liebermann wrote:
On Mon, 22 Aug 2011 21:06:55 -0400, micky wrote:

He calls it dry solder. Maybe that's the automotive term.

I've never heard of that term.

I think that is a left-ponder/right-ponder 'distinction'.

Dry Joint = UK

Cold solder = US

Thus it ever shall be

Ron(UK)

 

[whit3rd]

On Tuesday, August 23, 2011 12:48:06 AM UTC-7, Phil Allison wrote:

stra...@yahoo.com
... After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.


** What for ?

Solder flux is normally harmless and routinely left behind by many
manufacturers.

My favorite flux (water-soluble) isn't really compatible with resin-type
no-clean fluxes. So, cleaning off the old flux helps me redo the joint.
It's possible, too, that 'hot enough' iron for my flux is not suitable
to fully activate the (unknown, foreign) original flux residue.

It's also possible that what looks like flux is actually someone's
candlewax drip. Cleaning first is cheap insurance.

 

On Aug 23, 12:48 am, "Phil Allison" <phi...@tpg.com.au> wrote:

stratu...@yahoo.com

What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.

** What for ?

 Solder flux is normally harmless and routinely left behind by many
manufacturers.

....   Phil

Not the good ones. So, it's OK to be a slob just because you can?
Bollocks.

G˛

 

[Michael A. Terrell]

stratus46@yahoo.com wrote:

On Aug 23, 12:48 am, "Phil Allison" <phi...@tpg.com.au> wrote:
stratu...@yahoo.com

What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.

** What for ?

Solder flux is normally harmless and routinely left behind by many
manufacturers.

.... Phil

Not the good ones. So, it's OK to be a slob just because you can?
Bollocks.

Obviously, Phil has never done NASA or NATO approved soldering.


--
You can't have a sense of humor, if you have no sense.

 

[Phil Allison]

<stratus46@yahoo.com

"Phil Allison"

What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.

** What for ?

Solder flux is normally harmless and routinely left behind by many
manufacturers.

Not the good ones.

** Circular argument.

Solder flux IS routinely left behind by many major manufacturers ( both
now and for decades into the past) and clearly does no harm.


So, it's OK to be a slob just because you can?


** Seems to be the way you go about YOUR thinking.

Fuck off - imbecile.

 

[Phil Allison]

<stratus46@yahoo.com>
"Phil Allison"

stratu...@yahoo.com

"Phil Allison"

What the other say is true but I wanted to add, those pictures of the
'good' soldering job is substandard soldering. After cleaning off the
old solder with a solder sucker and/or wick, the old flux should be
removed and again after the new soldering.

** What for ?

Solder flux is normally harmless and routinely left behind by many
manufacturers.

Not the good ones.

** Circular argument.

Solder flux IS routinely left behind by many major manufacturers ( both
now and for decades into the past) and clearly does no harm.

So, it's OK to be a slob just because you can?

** Seems to be the way you go about YOUR thinking.

Fuck off - imbecile.

Look at the boards in you PC. See any flux?


** False argument again.

If leaving the flux behind on a PCB were a very bad thing, then you would
NEVER see it done by any equipment makers.

BTW:

Never hear of " NO clean " flux ???

Imbecile.



..... Phil