To Joe
Here are a couple of possible of control points I always check to help prevent random solder problems.
The age of components must be known. There are a lot of surplus components that get returned to customers or purchased by distributors for resale. These parts are then issued for use in new products since they already own them.
These leads can be compromised as they may be several years old and stored in a wide variety of bags, boxes in all types of conditions.
- Operators using their personal hand creams containing silicones are tougher to control. Even though you have silicone free hand creams at work I've seen operators going to their lockers and putting on their favorite hand creams. Then of course their is the salt and grease from lunch. Only training and careful controls at pre-wave assembly can reduce these risks.
- Another contamination point is oil or lubricants that a mechanic may have used on component prep or insertion equipment that migrated or with over-spray got into the blades or path of the component leads.
Remember even the strongest No-Clean flux is not even 30% as powerful when it comes to solids content and lead cleaning capability of the organic acids of water soluble fluxes.
----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: [log in to unmask]
Sent: Tuesday, February 10, 2009 4:54:02 PM GMT -05:00 US/Canada Eastern
Subject: Re: [TN] Part solderability
Dfx was not done properly.
--------------------------
Sent using BlackBerry
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Tue Feb 10 16:47:41 2009
Subject: Re: [TN] Part solderability
Many times we find that solderability problems
at the assembly level can't be confirmed by
solderability testing. Parts pass test just fine,
but we still have unacceptable rework.
Why?
Solderability varies among the parts in question.
A sample will test okay, but put a bunch of
parts into a mass soldering process, with normal
process variation, and even a few percent with poor
wets still cost a lot to touch up.
It can be maddening, but it doesn't happen that often,
so sometimes it's easier for us to just bite down hard
and send the parts out for hot solder dip.
-Joe
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
Sent: Tuesday, February 10, 2009 9:23 AM
To: [log in to unmask]
Subject: Re: [TN] Part solderability
Hi David
Well, the flux they are using is Alpha 615 (he didn't know what dash
number). Which adds to the mystery of why we get dewetting and they
don't because we also use Alpha 615-15 flux here, so his is either the
same or is 615-25 (higher solids).
Is Alpha 615 allowed for a J-STD-002 test?
My contact also advised that they do follow proper cal procedures for
the solder pot - not easy to verify from a distance.
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Monday, February 09, 2009 10:29 AM
To: [log in to unmask]
Subject: Re: [TN] Part solderability
Hi George! Yep, you summarized the flux change right on the money, in
fact, here is an equation for what you said: "...allow a known about of
activators, which would tend for the sample under test to show a little
better solderability than if just water white rosin was used =
consistency
and repeatability"! The use of water white rosin served the industry
well for many years but as we changed to new component and printed
circuit board surface finishes, the WW rosin had too large of a safety
factor and would sometimes results in "false negative" solderability
tests. The new test flux formulation is better matched to the material
sets the industry is now using. Graham will have to let us know if it
was a soldering process variable or solderability test inconsistency
that is causing the problem. A wetting balance test would provide a
dynamic wetting measurement that could be helpful too.
Dave
"Wenger, George M." <[log in to unmask]>
02/09/2009 08:15 AM
To
"TechNet E-Mail Forum" <[log in to unmask]>, <[log in to unmask]>
cc
Subject
RE: [TN] Part solderability
Dave,
Sorry but I just couldn't resist the opportunity to throw out my 2
cents. "Nothing tests soldering better than soldering". It is my
general understanding that the change to the flux in Revision B was to
allow a known about of activators, which would tend for the sample under
test to show a little better solderability than if just water white
rosin was used. If Graham's component supplier indicates the components
pass 002 using the old flux they should certainly pass using the Rev. B
flux but since he's having soldering problems there is either something
wrong with his soldering process or there really is a solderability
problem that 002 isn't detecting. My guess is the later and Graham is
finding out that Nothing tests soldering better than soldering".
Regards,
George
George M. Wenger
Andrew Wireless Solutions
Senior Principal FMA/Reliability Engineer 40 Technology Drive, Warren,
NJ 07059
(908) 546-4531 (Office) (732) 309-8964 (cell) [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Monday, February 09, 2009 8:47 AM
To: [log in to unmask]
Subject: Re: [TN] Part solderability
Hi Graham - yep, that's what I suspected. If they are following the
IPC/EIA JSTD-002C, they should be using a flux in accordance with
paragraph 3.2.2. which is a rosin type flux but has a very specific
recipe. The 002C committee changed the flux at Revision B and some folks
haven't noticed the change yet (hummm, if you are running a
solderability test, shouldn't you read the method!). The 002 committee
made the flux change based on an industry round robin test and the new
flux formulation provides better testing consistency and
reproducibility. There's nothing wrong with your soldering iron/RMA
flux test - it would defined as a soldering-ability test. The objective
of the JSTD-002C test protocols is
to provide a common baseline measure of the solderability of a component
finish and your soldering iron test is the same measurement but includes
specific attributes reflective of your soldering process. In 002C
Appendix E, there is a listing of the test flux products that were
submitted to the 002 committee - see if the flux being used is on that
list.
Dave
[log in to unmask]
02/09/2009 05:39 AM
To
"TechNet E-Mail Forum" <[log in to unmask]>, <[log in to unmask]>
cc
Subject
RE: [TN] Part solderability
Hi David
When I talked with them on Friday they told me they were using a rosin
flux and following J-STD-002. I didn't ask brand.
The one thing I asked them to do is to put a soldering iron on a few
leads (one at a time) and reflow the dip coating. We have found that we
can dip tin these parts here with RMA flux, and have them look great,
but when we try to install them in CCAs it's a disaster. We found that
applying a soldering iron on the lead we would find the solder would
dewet. (Not sure dewet is the right term, but hopefully you see what I
mean) I'm sure my test is not J-STD-002 compliant, but it works for
me...
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, February 06, 2009 8:03 PM
To: [log in to unmask]
Subject: Re: [TN] Part solderability
Hi Graham - Please find out what flux (i.e. product name: Kester XXX or
Alpha YYY or Indium ZZZ, etc.) the component fabricator used in his
test.
Also find out which solderability specification did they use
(IPC-JSTD-002C or MIL-STD-XXX) and which solderability test method did
they use (Method A or B or...). If you can get those facts, I can tell
you if they followed the specification requirements. My guess is that
they used an incorrect flux.
Dave Hillman
JSTD-002 specification Chairman
[log in to unmask]
Graham Collins <[log in to unmask]> Sent by: TechNet
<[log in to unmask]>
02/06/2009 08:12 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
[log in to unmask]
To
[log in to unmask]
cc
Subject
[TN] Part solderability
Hi guys.
A while back I rejected a bunch of parts due to non wetting when we went
to solder them.
The manufacturer has come back with a response to our guys, saying that
they did a steam aging test on them and they passed fine. He wants to
discuss it with us.
Obviously this is not good - they pass his test but I can't solder the
things. Which makes me suspect his test... but makes him suspect my
process. I don't know enough about steam aging tests to discuss this
well. Obviously I need to ask what kind of flux he is using, but
anything else?
Our process is SnPb, we use RMA flux, and the wave soldering machine
runs at 500F for the pot. This is on an assembly that we have happily
built for about 7 years, with the same manufacturer of part, and no
process changes that I can identify as significant. The part is what I
would call marginally solderable, if we hand solder it and put a fair
bit of heat to the lead we can get it to solder, but not well or easily.
No previous soldering issues with the part.
regards,
Graham Collins
Halifax Production Engineering
L-3 communications Electronic Systems
(902) 873-2000 ext. 6215
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