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| Reply To: | TechNet E-Mail Forum. |
| Date: | Wed, 29 Jan 2003 18:03:59 -0600 |
| Content-Type: | text/plain |
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Hi Jean-Francois! The various Technet replies have demonstrated that just
specifying a pwb finish will not necessarily result in a long shelf life.
The implementation of immersion tin is a great example - there are
immersion tin chemistries which have shelf lives ranging from 3 months to
12 months. A reasonable pwb shelf life expectation for most pwb surface
finishes (and yes included in that list would be immersion tin, OSPs, and
HASL) would be 12 months in good storage conditions (21 C, 30-60% RH). You
should be aware that not all of the surface finishes available on the
market can meet a 12 month shelf life - ask your surface finish provider
just how long they guaranty the solderability as tested per ANSIJ-STD-003A.
The shelf life of a pwb surface finish is not only dependent on the pwb
fabricator's process but also on your soldering process (flux selection,
baking cycles, temperature extremes, etc.) so working closely with your pwb
supplier is very important. Good Luck.
Dave Hillman
Rockwell Collins
[log in to unmask]
"Bissonnette,
Jean-Francois" To: [log in to unmask]
<JBissonnette@WAB cc:
TEC.COM> Subject: [TN] Shelf life of PWB
Sent by: TechNet
<[log in to unmask]>
01/29/2003 02:54
PM
Please respond to
"TechNet E-Mail
Forum."; Please
respond to
"Bissonnette,
Jean-Francois"
What is the shelf live of a PWB. After how long can I expect to have
solderability problem?
Thanks!
Jean-François Bissonnette
Vérificateur, Contrôle de la Qualité
Électronique
Produits et Procédés
Vapor Rail Inc.
10655 Henri-Bourassa O.
St-Laurent, Qc
H4S 1A1
(514) 335-4200 x2021
(514) 335-4231 fax
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