Hi Franklin! I always say "high performance" rather than "military" or
"high reliability" as those are better descriptors. The difference between
industrial electronics versus high performance electronics is the use
environment and the criticality of the application. The last time I
checked, there wasn't a switch on the wave solder machine for making IPC
Class 2 versus IPC Class 3 solder joints (we make the same solder joint
but use different requirement criteria for the different use
environments)! A couple additional points for the discussion are the
disadvantages of a lead-free HASL process (Keith listed a number of the
advantages) - a lead-free HASL finish is less coplanar than the immersion
finishes and a lead-free HASL finish has a greater impact on the pwb
copper features in terms of copper dissolution and thermal exposure
induced reliability degradation. All of our industry pwb finishes have
both advantages and disadvantages - just need to understand how they fit
your application.
Dave
Franklin Asbell <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/11/2008 08:28 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Franklin Asbell <[log in to unmask]>
To
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cc
Subject
Re: [TN] Lead-free HASL finishes
Not 'high performance', just military (hmmm, now what does that tell us?)
Franklin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, January 11, 2008 8:05 AM
To: [log in to unmask]
Subject: Re: [TN] Lead-free HASL finishes
Hi Richard! What is your concern of using an immersion tin finish for high
performance pwbs?
Dave Hillman
Rockwell Collins
[log in to unmask]
"Stadem, Richard D." <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/10/2008 03:20 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
"Stadem, Richard D." <[log in to unmask]>
To
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cc
Subject
Re: [TN] Lead-free HASL finishes
No.
I want to ensure that these two PWB surface finishes (not the component
finishes) never show up on PWBs intended for military use
unintentionally, by mistake, in place of standard tin/lead HASL or fused
Tin/Lead.
Imagine the implications.
But I also want to know what the controlling standards are, so I can
understand fully what the implications are if it did happen, from a
reliability standpoint, and what the standards require (if anything)
that would prevent such a thing from happening. I would expect to see
some type of labeling or other control methods. And no, it did not
happen anywhere that I know of. I just want to make sure it doesn't.
Thanks Phil and Dewey. I found the 4554. Are there any other tin-only
PWB finishes other than Immersion Tin out there?
-----Original Message-----
From: Phil Nutting [mailto:[log in to unmask]]
Sent: Thursday, January 10, 2008 3:06 PM
To: (Leadfree Electronics Assembly Forum); Stadem, Richard D.
Subject: RE: Lead-free HASL finishes
Richard,
HASL is Hot Air Solder Leveling, using actual molten solder.
Immersion tin and matte tin are chemical bath processes.
These are two completely different processes.
Are you trying to meet a customer request?
Phil
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Thursday, January 10, 2008 3:54 PM
To: [log in to unmask]
Subject: [LF] Lead-free HASL finishes
I know that some of you had discussion about this topics on the forums,
but I just wanted to verify that when we are talking about Pb-free HASL
we are talking about Immersion Tin finish. Correct? Or are there other
Pb-free HASLs that are different? Are there different products such as
matte finish Pb-free HASL versus some other type of Sn finish?
And is there an IPC standard for Pb-free HASL?
I am not talking about RoHS -compatible finishes, such as ENIG, ENEPIG,
IAg, OSP, etc., just lead-free HASL finishes.
Is there a Pb-free fused tin finish?
What standards are being developed or have been developed for Immersion
Tin finishes? I could not find any at IPC.org, but I may have missed
them. I know of IPC 4552 for ENIG, 4553 for Immersion Silver, etc. but
could not find a similar standard for Immersion Tin finish.
Thanks for any help you can provide.
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