Hi Joyce! Yep, IPC-TR-464 plus addendum, I know that report very well. The
JSTD-002 and 003 committees are working on changing the industry culture on
"aging". There have been a number of studies and investigations since the
publication of the 464 report that demonstrates we really don't "age" a
surface in an identical manner as Mother Nature with the use of steam
and/or baking - in fact many times we can create a surface the doesn't
resemble a naturally aged surface at all (e.g different oxide species,
thicknesses, etc.). You will find that both the 002 and 003 specifications
now use the term "conditioning" to describe an accelerated treatment
process on a surface. There have been too many instances where someone
tries to correlate X amount of steam conditioning as X number of months of
storage without having demonstrated the resulting conditioned surface
structure/species is the same as a naturally aged surface. The committees
are now working on what is an appropriate conditioning methodology that
isn't unnecessarily harsh but does reflect natural surface conditioning.
Lots of work ahead but the committee's are going to make an attempt to
improve the specifications. The Alternative Final Finishes committee is
also working on the issue.
Dave
"joyce"
<[log in to unmask] To: "'TechNet E-Mail Forum.'" <[log in to unmask]>, <[log in to unmask]>
om> cc:
Subject: RE: [TN] Raw card solderability
04/28/2003 09:47
AM
Please respond to
joyce.koo
Dave,
I believe IPC has a Tech report on different finishing againest steam
aging testing and solderability. I believe it is also including the
storage infor as well. Very old doc. I think.
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Hillman
>Sent: Monday, April 28, 2003 10:17 AM
>To: [log in to unmask]
>Subject: Re: [TN] Raw card solderability
>
>
>Hi Bill! I don't know of an IPC specification that designates
>a given period of shelf life for an of the available pwb
>finishes. The general consensus for shelf life of either
>components or pwbs within the JSTD-002 and JSTD-003 committees
>is one year. However, that one year figure is not a
>requirement. The shelf life of a specific pwb finish is
>negotiable between yourself and your pwb fabricator. Many of
>the pwb finishes types (immersion gold, immersion silver,
>immersion tin, HASL, OSP) can easily have one year shelf life
>when properly applied, properly handled and adequately stored.
>Also realize that some pwb finishes (e.g. thin OSP coating
>family) are not designed for one year storage. Good Luck.
>
>Dave Hillman
>JSTD-002/003 Chairman
>[log in to unmask]
>
>
>
>
> Bill Page
> <bill.page@SANMIN To:
>[log in to unmask]
> A-SCI.COM> cc:
> Sent by: TechNet Subject: [TN]
>Raw card solderability
> <[log in to unmask]>
>
>
> 04/25/2003 03:48
> PM
> Please respond to
> "TechNet E-Mail
> Forum."; Please
> respond to Bill
> Page
>
>
>
>
>
>
>Consider this a hypothetical question :)
>
>We have some fabs that, due to reduced production
>requirements, have been in house for an extended period of
>time (more than a year). In investigating some solderability
>concerns, the board house suggested that with thinner HASL
>coatings, copper migrates through the tin-lead coating,
>reducing solderability. The vendor seemed to think that a
>six-month shelf life is now an industry standard...indeed, he
>involved the magic name of IPC.
>
>It has, admittedly, been a long time since I considered myself
>up to date on PCB fabrication issues.
>
>a. Is this a legitimate observation from our supplier?
>b. Should we expect only a six month shelf life on PCB?
>c. What rework method is recommended to bring these back in spec?
>
>Thanks,
>
>Bill Page
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