Personally I see almost no merit in using ROSE testing on uncleaned
assemblies. The test was originally intended to determine remaining quantity
of Ionics after cleaning. The qualitative aspect was taken care of by
narrowing the choice of fluxes to those on an approved list. IOW: Such and
such an amount of contamination is OK if from that type of flux. Keep in
mind these instruments are quite sensitive. Way back when we used to have
philosophic discussions on the significance of the CO2 gulp on lifting the
test tank lid. Certainly touching an assembly briefly with a naked finger
can send readings "off scale".
Putting an uncleaned assembly through ROSE will produce a huge number
(relatively speaking) which will come from all sorts of sources, including
just leaving an assembly lying about. The number is big enough that you
could have swings and counter swings from different sources. A small spot of
contamination will be averaged into the total number, and so on. To me it's
like looking at an ammeter in a building's electricity supply line to see if
someone has left a room light on. Yes you can tell if everything else is
off, but if not then...?
Regards
Mike Fenner
Bonding Services & Products
M: +44 [0] 7810 526 317
T: +44 [0] 1865 522 663
E: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: Friday, July 13, 2012 3:14 PM
To: [log in to unmask]
Subject: Re: [TN] [TN] Ionic Contamination Test for Non-clean PCBA, is it
really necessary?
We love it when you talk dirty.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Naisbitt
Sent: Friday, July 13, 2012 7:07 AM
To: [log in to unmask]
Subject: Re: [TN] [TN] Ionic Contamination Test for Non-clean PCBA, is it
really necessary?
Fellow Techies,
Ionic Contamination Testing is a fast, accurate and reliable way to control
your assembly process.
ROSE testing ought to be consigned to history. At one time the US DOD wanted
to have a stake in the ground to better define what is acceptable and
unacceptable in terms of "cleanliness" hence the ROSE test was born and
setting a level of acceptance. This has caused more confusion and argument
in our industry than it reasonably deserves.
Tan Geok - in 1995 GEC Hirst Research determined that there are AT LEAST 16
different types of "white powder residues". You are not at all correct to
state that the flux residue will become white and, by inference, that this
is a bad thing. It might simply be cosmetic. How so? Because of a trapped
particle within the board surface that refracts the light in a different way
that "shows it to be white" - this might simply be pure and inert rosin. Of
course it could also be something far more sinister.
If I might be so bold, there will be an SMTA Conference in Chicago in
November on Cleaning and Coating. I shall be presenting a revised test
method that everyone assembling electronic circuits would benefit from, if
it is used correctly. If anyone wants the method, let me know, but I need a
few more weeks to complete the job.
Finally, and for the record, there are many systems in the market place that
are, in many cases, superior in performance and accuracy than either the
OmegaMeter or the Ionograph. There is also the Zero-Ion, the CT100 and our
Contaminometer - ALL of which deserve recognition. Hows that for fair play?
So, to answer the original question - is it really necessary? If you want a
fast and accurate control of your assembly process - yes.
Graham Naisbitt
Gen3 Systems
On 11 Jul 2012, at 08:40, Tan Geok Ang wrote:
> Ask your customer to pay for the PCBA once it undergoes the Ionic
Contamination Test with Omega tester as the flux residue will become white
residue on the PCBA. Who is your customer who might advice you how to go
about the process.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of WTSJ-Willis Tam
> Sent: Wednesday, 11 July 2012 3:14 PM
> To: [log in to unmask]
> Subject: [TN] 答复: [TN] Ionic Contamination Test for Non-clean PCBA, is
it really necessary?
>
> Bob,
>
> The Omega Test is not yet set up, as I don't have the test result now.
>
> Actually, we don't want to set up such a test.
>
>
> Regards
> Willis Tam
>
>
> -----邮件原件-----
> 发件人: TechNet [mailto:[log in to unmask]] 代表 Robert Kondner
> 发送时间: 2012年7月10日 21:50
> 收件人: [log in to unmask]
> 主题: Re: [TN] Ionic Contamination Test for Non-clean PCBA, is it really
> necessary?
>
> Willis,
>
> I would be curious to hear the test restuls.
>
> Do you have any rework ( :-) ) and do you need to clean that for cosmetic
> appearance? If so soes that cleaning affect the No Clean flux?
>
> Thanks,
> Bob K.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of WTSJ-Willis Tam
> Sent: Tuesday, July 10, 2012 12:13 AM
> To: [log in to unmask]
> Subject: [TN] Ionic Contamination Test for Non-clean PCBA, is it really
> necessary?
>
> Hi Technet,
>
> We have implemented non-clean SMT and wave soldering processes for more
than
> 10 years and there's no any issue, but recently one of our new customer
> required us to buy the Omega tester and set up the Ionic Contamination
test
> for the non-clean PCBA, according to IPC-TM-650. 2.3.25.
>
> We feel the Ionic Contamination test might not be an appropriate test for
the
> non-clean PCBA, but is there any technical paper or industry standard for
> this topic? We need some supporting documents for further discussion with
our
> customer.
>
> Any suggestion/feedback would be appreciated.
>
> Regards
> Willis Tam
>
>
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