Brian.
Could you please tell me what sample size is usually used for production
approval (dip test) after storage more than 1/2 year after the first test at
incoming inspection? Maybe there should be another approach- in production
test of a certain number of mounted circuits and full visual
inspection -even X-ray-afterwards?
Of course. I think that no supplier would receive failed components after
1/2 year back. and if desperately needed and there is no chance of receiving
new components soon. there must be found a solution to use them-hand
soldering, coating renewal, or else....
Thank you very much, I as usually appreciate your answers very much.
Gaby
----- Original Message -----
From: "Brian Ellis" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, May 11, 2003 8:37 AM
Subject: Re: [TN] Wetting Balance Testing
> I disagree entirely with this view. You may let pass some components
> with marginal solderability which will have deteriorated to unsolderable
> before they even reach the production line, and it does not allow for
> tolerances in the flux composition and activity. You must have something
> that demonstrates the worst case scenario. Believe me, this is the voice
> of experience.
>
> Brian
>
> Reuven ROKAH wrote:
> > Hi Dave,
> > I think that testing with "no clean flux" that is uses in production
line
> > is more practical than "R" type rosin. Its more aggressive, so if it
fail,
> > it will represent the future results in the real life in production.
> >
> > Best Regards
> >
> > ROKAH Reuven
> >
> > e mail: [log in to unmask]
> >
> >
> >
> > Dave Hillman
> > <ddhillma@ROCKWELLC To:
[log in to unmask]
> > OLLINS.COM> cc:
> > Sent by: TechNet Subject: Re: [TN]
Wetting Balance Testing
> > <[log in to unmask]>
> >
> >
> > 09/05/03 03:23 PM
> > Please respond to
> > "TechNet E-Mail
> > Forum."; Please
> > respond to ddhillma
> >
> >
> >
> >
> >
> > Hi folks! Just an FYI but one of the major changes in the recently
released
> > JSTD-002B specification is a revision of the flux chemistry for
> > solderability testing. The committee spent an enormous amount of
resources
> > on investigating the flux chemistry change. The new flux chemistry is a
> > standardized, specified, activated flux formulation which replaces the
old
> > "R" flux chemistry. The flux chemistry change was the result of industry
> > feedback - with the advent of new component surface finishes and solder
> > alloys the use of an "R" flux chemistry was resulting in false negative
> > solderability responses. Additionally, the use of "R" flux was one
> > contributor of testing variation and the new standardized flux
formulation
> > contributes to less test variation without unduly influencing the test
> > results. Jack Crawford at the IPC Office has a Flux Justification Memo
> > which explains the committee's efforts and has the committee test
results -
> > I recommend anyone who is conducting solderability testing to get a
copy.
> >
> > Dave Hillman
> > JSTD-002 Committee Chair
> > [log in to unmask]
> >
> >
> >
> >
> > Brian Ellis
> > <b_ellis@PROTONIQ To: [log in to unmask]
> > UE.COM> cc:
> > Sent by: TechNet Subject: Re: [TN]
Wetting
> > Balance Testing
> > <[log in to unmask]>
> >
> >
> > 05/09/2003 02:05
> > AM
> > Please respond to
> > "TechNet E-Mail
> > Forum."; Please
> > respond to Brian
> > Ellis
> >
> >
> >
> >
> >
> >
> > Except for when you are doing flux comparisons, wetting balance tests
> > are used for determining the solderability. To obtain consistent results
> > you should always use the least active flux so as to reveal all the
> > faults. If something solders well with this, it will solder with any
> > flux. Therefore it is normal to use a pure, unactivated WW rosin flux
> > (usually 25%w/w). That way, you can get reproducible conditions with
> > your suppliers and/or other plants.
> >
> > Brian
> >
> > Braddock, Iain wrote:
> >
> >>Why # 1, why would you not want to test with the flux you are using on
> >
> > your
> >
> >>production?
> >>
> >>Iain.
> >>
> >>-----Original Message-----
> >>From: Munie, Gregory [mailto:[log in to unmask]]
> >>Sent: 08 May 2003 15:11
> >>To: [log in to unmask]
> >>Subject: Re: [TN] Wetting Balance Testing
> >>
> >>
> >>
> >> *** WARNING ***
> >>
> >>
> >>
> >>This mail has originated outside your organization,
> >>
> >>either from an external partner or the Global Internet.
> >>
> >> Keep this in mind if you answer this message.
> >>Neil
> >>
> >>I've done a lot of wetting balance but I have to add a few comments on
> >
> > the
> >
> >>"dip and look." (I agree with all Bev's other comments and suggestions.)
> >>
> >>The dip and look as it's traditionally done does deserve to die. But if
> >
> > done
> >
> >>correctly it can tell you almost as much as wetting balance.
> >>
> >>And I define correctly as:
> >>
> >>1) Use ONLY water white rosin flux. NEVER use any activators in the
flux.
> >>
> >>2) Control your immersion (wetting balance is good for this :-)
> >>
> >>3) Coverage criteria means nothing if you don't see active wetting, i.e.
> >>solder rises ABOVE the surface of the bath to wick UP the part lead.
> >>
> >># 3 is absolutely critical: in a real world soldering situation that is
> >>exactly what you want to happen for either wave or reflow soldering.
It's
> >>what happens to the section of the lead that's NOT in direct contact
with
> >>the solder that tells you whether the part is solderable.
> >>
> >>Greg Munie
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>Original Message-----
> >>From: Bev Christian [mailto:[log in to unmask]]
> >>Sent: Thursday, May 08, 2003 4:25 AM
> >>To: [log in to unmask]
> >>Subject: Re: [TN] Wetting Balance Testing
> >>
> >>
> >>
> >>Neil,
> >>
> >>You also need to consider what alloy you are using. Dr. Lee of Indium
> >
> > has
> >
> >>shown that 62/36/2 Sn/Pb/Ag gives significantly different results. And
> >
> > then
> >
> >>there is the work Chris Hunt et al of the British NPL have done on lead
> >
> > free
> >
> >>solders. And then are you using a solder globule or solder bath? Don't
> >>forget temperature, atmosphere (most likely air, unless like Chris you
> >
> > can
> >
> >>afford a dry box) and preheat (or is that what you mean by hang time?).
> >
> > If
> >
> >>you are using a globule block we have also found that how centered your
> >>component lead is over the solder globule affects your results as well.
> >>
> >>I would say it is not so much the length of the lead (unless you are
> >
> > talking
> >
> >>about something obscenely long - no comments please), but rather what
the
> >>lead is connected to - like an internal heat sink. And, yes, we have
had
> >>ONE problem with the heat sinking ability of a component affecting the
> >>results. I gave a short presentation to the J-STD-002 committee at
APEX.
> >
> > I
> >
> >>will send you a copy. It will not show up for other TechNetters,
> >>unfortunately. In essence, we found that wrapping the wetting balance
> >
> > clip
> >
> >>in polyimide tape allowed the component in question to pass
solderability
> >>testing!
> >>
> >>All said, we have had excellent results using a wetting balance and much
> >>prefer it to the dinosaur "dip and look" test, which I would like to see
> >
> > DIE
> >
> >>for SMT components. Now if we can just agree on what pass/fail criteria
> >>will be....
> >>
> >>regards,
> >>Bev Christian
> >>Research in Motion
> >>
> >>-----Original Message-----
> >>From: Neil Flatter [mailto:[log in to unmask]]
> >>Sent: May 8, 2003 1:17 AM
> >>To: [log in to unmask]
> >>Subject: [TN] Wetting Balance Testing
> >>
> >>
> >>For those of you doing solderability testing, what sorts of parameters
> >>should we be concerned about for reliable results? Our tester already
> >>allows inputs for lead perimeter, cross sectional area, and hang time.
> >
> > My
> >
> >>company's testing also specifies immersion angle, depth, and speed as
> >
> > well
> >
> >>as the type of flux. By controlling these factors, can I expect
> >
> > repeatable
> >
> >>results?
> >>
> >>It has been suggested that we also need to limit the length of the leads
> >
> > for
> >
> >>our testing as wall as installing a thermal break between the lead and
> >
> > the
> >
> >>hanger. Both have been blamed for failing test results. Has anyone
> >>experienced changes in test results from these variables?
> >>
> >>Neil Flatter
> >>TRW-Automotive
> >>Process Quality
> >>
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