Hi Santhakumar,
The Massachusetts Lead Free Consortium has conducted two phases of LF
reliability testing with some of the parameters you mention. We
utilized five lead-free board finishes (HASL, matte Sn, OSP, immersion
Ag, and ENIG), two atmospheres (air and N2), and three flux
formulations of NEMI SAC solder paste, using component leads finished
with matte tin, NiPdAu, NiAu and SnAgCu.
I just tried unsuccessfully to attach our most recent paper. (I can
send it to you directly if wish - respond to me off-line), Meanwhile,
you can find older papers summarizing our work on our webpage (plus a
lot of other great LF presentations) at:
http://www.turi.org/messages/lead_free_electronics.htm
The good news that we found is that reliable lead free assembly is
possible - if you do your homework.
Good luck!!
Todd MacFadden
Project Manager of Research and Training
Toxics Use Reduction Institute
University of Massachusetts Lowell
978.934.3391
[log in to unmask]
www.turi.org
----- Original Message -----
From: santhakumar rajesnayagham <[log in to unmask]>
Date: Thursday, May 6, 2004 11:48 am
Subject: [LF] reliability study on SAC with various PCB and component
finish combinations
> Hi All,
> Has anybody performed reliability studies on the following
> combination?Solder paste: SAC (any combination)
> PCB finish: Immersion Silver or Immersion Tin
> Component finish: any lead-free finish is ok
> for a variety of components?
> Thank you,
> Sincerely,
> Santhakumar
>
>
>
> Fern Abrams <[log in to unmask]> wrote:Just to clarify, IPC filed
> comments with the EU Technical Adaption
> Committee regarding the need for clarification proposed definition of
> LF:
>
> "A maximum concentration value of 0.1% by weight in homogeneous
> materials
> for lead, mercury, hexavalent chromium, polybrominated biphenyls (PBB)
> and
> polybrominated diphenyl ethers (PBDE) and of 0.01% weight in
> homogeneousmaterials for cadmium shall be tolerated. Homogeneous
> material means a
> unit
> that can not be mechanically disjointed in single materials".
>
> While I have had no formal response, we have heard informally that
> thisis unlikely to be further clarified and may end up being
> settled in
> court.
>
> Fern Abrams
> Director of Environmental Policy
> IPC - The Association Connecting Electronics Industries
> 1333 H Street, NW, 11th Floor West
> Washington, DC 20005
> (202) 962-0460
> fax (202) 962-0464
> www.ipc.org
>
>
>
>
> -----Original Message-----
> From: Bev Christian [mailto:[log in to unmask]]
> Sent: Wednesday, May 05, 2004 4:49 PM
> To: [log in to unmask]
> Subject: Re: [LF] Lead in resistors
>
> Gordon,
> No, not very comforting.
>
> The IPC Materials Declaration Team has sent a letter to the
> appropriateEU personnel asking for clarification of some of these
> issues, but to
> the best of my knowledge Fern has still not received an answer.
> This is
> probably because they (EU) had not thought that far ahead when they
> drafted the dreadful thing in the first place. As more than one
> wag has
> stated, we will probably have to wait for clarification when that
> firstunfortunate company is dragged into court. Then we MIGHT get
> definitiveanswers.
> regards,
> Bev Christian
> Research in Motion
>
> -----Original Message-----
> From: Davy, Gordon [mailto:[log in to unmask]]
> Sent: May 5, 2004 4:26 PM
> To: [log in to unmask]
> Subject: Re: [LF] Lead in resistors
>
>
> Bill Haas has noted that 0402 surface-mount "lead-free" resistors were
> found to contain more than 1000 ppm Pb, and that the suppliers assured
> him that this is OK per the RoHS legislation. Bill wanted to know
> whereit says in the directive that what the resistor manufacturers
> told him
> is so. Annex item 7 exempts Pb in "electronic ceramic parts (e.g.
> piezoelectronic devices)", so it looks as if this is what they are
> referring to.
>
> What the Directive doesn't say anywhere, of course, is that for
> components not exempted by the Annex the maximum allowable level
> is 1000
> ppm, or how the limit (whatever it turns out to be) is to be
> calculated- i.e., what is to be used as the fraction denominator:
> terminationfinish, component as a whole, assembly as a whole,
> equipment as a whole.
> Article 4 paragraphs 1 and 2 say that there can't be any Pb at all
> except per the Annex, and paragraph 3 puts manufacturers on notice
> thatthey may have to eliminate other stuff later.
>
> Also not spelled out is how users of components - such as Bill - are
> expected to document that the equipment items that they are
> selling are
> Pb-free: will the envirocops be satisfied if the equipment
> manufacturercan produce upon demand a certificate of compliance
> from the
> manufacturers of each component? If not, how diligent does the
> originalequipment manufacturer have to be to ensure that no Pb
> above the
> to-be-determined limit (except as permitted by the Annex) has
> crept into
> his product?
>
> As an analogy, hardware destined for space has long had a prohibition
> against pure tin plating. Yet every time a satellite has been audited,
> cases of pure tin plating have been found, due simply to human error.
> Can you imagine the jeopardy of the manufacturer of an electronic
> system, wondering if a particular item will be randomly selected
> to find
> out if it contains Pb? (X-ray fluorescence will be useless for
> levels of
> 1000 ppm, so if that's the level that is finally chosen, we're talking
> serious chemical analysis.)
>
> Article 8 specifies that the penalties are to be "effective,
> proportionate, and dissuasive." I don't see any language
> describing how
> disagreements are to be resolved, or what happens to the equipment
> whilethe matter is being settled. Not very comforting.
>
> Gordon Davy
> Baltimore, MD
> [log in to unmask]
> 410-993-7399
>
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> ------------
>
>
> Santhakumar Rajesnayagham
> Graduate Student & Research Assistant
> Center for Electronics Manufacturing and Assembly (CEMA)
> Rochester Institute of Technology, Rochester, New York
> Phone : (CEMA Lab) 585-475-7293
>
>
>
>
>
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