The Omegameter will certainly give you a measure for ionics, but not non
ionics. For example the stripper mentioned for removing conformal coatings
is likely to be solvent based. It's not ionic but any residues would
certainly continue to soften coatings and interfere with any recoating.
It may well be that the residual ionics could serve as an indicator for the
overall effectiveness of the various cleaning processes employed, but the
actual relationship between them and cleanliness/reliability ought really
to be established and quantified on a case basis. Some companies do give
guide numbers which are around 10% or so of the old MIL level, but I don't
know how these numbers came about.
Regards
Mike Fenner
Applications Engineer, European Operations
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
E: [log in to unmask]
W: www.indium.com
Leadfree: www.Pb-Free.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of joyce
Sent: Friday, December 20, 2002 2:19 PM
To: [log in to unmask]
Subject: Re: [TN] Cleanliness measurement equipment
Mel,
Why omega meter is not good for water soluble fluxes? I thought it
extracts using IPA/DI mixture, it should extract water soluble flux
residue readily.
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Mel Parrish
>Sent: Friday, December 20, 2002 9:15 AM
>To: [log in to unmask]
>Subject: Re: [TN] Cleanliness measurement equipment
>
>
>Hi Peter,
>Can't imagine the Omega meter type of tests to be of any
>value. Especially when considering the use of Water Soluble
>fluxes. Why not send them out for test to someone that can
>justify the capital investment for serious cleanliness test resources.
>
>Mel Parrish
>Director, Training Materials Resources
>Soldering Technology International
>102 Tribble Drive
>Madison, AL 35758
>256 705 5530
>256 705 5538 Fax
>[log in to unmask]
>www.solderingtech.com
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of
>[log in to unmask]
>Sent: Thursday, December 19, 2002 10:16 PM
>To: [log in to unmask]
>Subject: [TN] Cleanliness measurement equipment
>
>
>Dear All,
>
>What would your recommendations be for equipment to measure
>board cleanliness under the following circumstances?:
>
>Number of boards = 10 pcs per month up to a total of 280
>boards. Board size = typically VME - approx 9.5" x 6.5" Board
>type = FR4, Class 3, 10 or 12 layer ENIG or HASL finished.
>Assembled with 63/37 solder paste and water-soluble flux,
>reworked using Kester 63/37 cored solder with compatible w/s
>flux Other main residues would come from fingerprint oils and
>residues from stripping Humiseal off boards using Conformox or Forane.
>
>I am trying to set up a new capability here and am looking for
>the least expensive equipment that will reliably measure
>genuine cleanliness levels down to 0.02ug NaCl eq/cm^2. I can
>only justify equipment expenditure against this one small
>contract that involves a total of 280 boards, hence the need
>for cost-effective (aka low-cost) choices. So far, I see that
>the Omegameter still features heavily in discussions on this
>topic - is it still a good tool to use, or is it's technology
>too old now to be capable of measuring accurately the high
>levels of cleanliness demanded by today's high-reliability
>electronics? Other options, like the Zero-Ion, or Concoat's
>Contaminometers, good as they seem to be, are several
>magnitudes more expensive and harder to justify as a result
>unless there's a good reason why less expensive options are
>not suitable.
>
>I could also use your recommendations on SIR test equipment.
>
>Thanks for any help you can offer.
>
>Peter
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