Cots-jit nice. How about PWB shelf life? Specifically, osp finishing. Any idea how to preserve and prolong the life? (Not strip and recoat). Thx.
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----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu Nov 05 04:05:17 2009
Subject: Re: [TN] Component Shelf Life
If the shelf is stainless steel, it will last for ever. Wooden shelves will rotten in humid atmosphere. Plastic shelves have limited life.....he-he..not Friday yet? The question is interesting. Our philosophy is that COTS should be regarded as buying bread, i.e. use the components as soon as possible from manufacturing date. Thus, components come to the factory input one day, and a few days later, they are mounted. This is the ideal picture, but it won't work for all, especially not for our MIL production, where we are obliged to have spare parts for up to 30 years. How can we rely on components that are stored that long time? Our experience is, that most components have a surprisingly long freshness if they are stored in a dry environment. I have tested old 2N1932s, connectors, relays and other components, that have been stored that long time, and they appear like manufactured yesterday. It seems to me, that the 'only' parameter that can cause trouble is solderability. Sad enough, some finishes won't be reliable even if stored in a ideal atmosphere, because of inherent diffusion processes. We plan to buy a solderability tester (wetting balance)for doing 100% sample testing. If the components pass that test, there is a good chance that the leads have a reliable finish. Cross sectioning and SEM analysis would be a further assuraance, but will be too expensive.
Now, how many assure themselves by doing such extensive solderability testing? Are there any at all? And is such a performance regarded as a sufficient tool?
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: torsdag 5 november 2009 01:09
To: [log in to unmask]
Subject: Re: [TN] Component Shelf Life
Paymon,
Got too busy at work to reply. I am now signed on here at home, after a nice meal and after watching the news with my wife. Yes, I am a guy.
Shelf life will affect solderability, which may affect things like % off pad, etc. and the pass/fail criteria for this sort of thing varies depending on whether you are building class 1, 2 or 3 product.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paymon Sani
Sent: Wednesday, November 04, 2009 3:35 PM
To: [log in to unmask]
Subject: Re: [TN] Component Shelf Life
Hello Bev, Gregg,
Thank you for getting back to me. I am curious now, how is it related to the IPC class?
Regards,
Paymon Sani
Quality Engineer
Creation Technologies
Office: 905.754.5000 x 5363
[log in to unmask] | www.creationtech.com
-----Original Message-----
From: Bev Christian [mailto:[log in to unmask]]
Sent: Wednesday, November 04, 2009 10:20 AM
To: TechNet E-Mail Forum; Paymon Sani
Subject: RE: [TN] Component Shelf Life
Paymon,
Gregg hit it on the nail head.
In addition, it is going to depend on finish, finish thickness (varies) and what your level of acceptability is (which IPC class product do you build?).
I also do not know of a published, recent standard on this topic.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paymon Sani
Sent: Wednesday, November 04, 2009 9:54 AM
To: [log in to unmask]
Subject: [TN] Component Shelf Life
Dear Colleagues,
I am looking for a standard for component shelf life. Is anyone aware of such document?
Best Regards,
Paymon Sani
Quality Engineer
Creation Technologies
Office: 905.754.5000 x 5363
110 Clegg Road | Markham, ON, Canada | L6G 1E1 [log in to unmask]<mailto:[log in to unmask]> | www.creationtech.com<http://www.creationtech.com/>
[cid:[log in to unmask]]Working together to build the future
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