TECHNET Archives

May 2003

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Dave Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 12 May 2003 07:54:58 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (225 lines)
Hi Rokah! The methodology you describe can be used provided you have a very
good partnership with you component fabricators but you do assume some risk
as testing with your production flux allows for no safety factor for
potential solderability issues. The methodology issue you raise is one
which the 002 committee constantly works to attain a balance - the 002
specification is designed to determine the robustness of a finish and at
the same time allow the specification user a predictive window of how those
components would perform in a production operation. With the wide variety
of flux materials and the various soldering processes, it is not an easy
task of creating a specification which benefits the entire industry.

Dave



                      Reuven ROKAH
                      <Reuven.Rokah@ECI        To:       [log in to unmask]
                      TELE.COM>                cc:
                      Sent by: TechNet         Subject:  Re: [TN] Wetting Balance Testing
                      <[log in to unmask]>


                      05/11/2003 01:04
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      Reuven.Rokah






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]>


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]>



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
>
>
>      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

---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------

ATOM RSS1 RSS2