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Danger Will Robinson. Danger.
voltage + humidity + silver + close proximity = ?
check your textbook if you don't know how to spell migration
(Feb '92 issue of SMT "Conductive Epoxy Adhesives to Replace Solder" last
paragraph)
i am personally in the middle of an ugly one right now related to this. we
unwittingly spec'd an ink with ~30% silver content onto a phone keypad.
the application had nominally 10 mil spacing and 3.3vdc applied. classic
migration shows and keypad stops working after 3-4 weeks at 50C/95%RH.
Bummer. That's about ambient in India during Monsoon season. Guess where
our beta was? =8-0
good news is it's early in the program and we're recovering fine.
bottom line: if it's got silver and it's not encapsulated (e.g. s/m or
conformal coat) you won't see me signing off on it.
see ya,
dwight
staff qe
At 6:37 PM 11/14/96, Aric Parr wrote:
> We have multiple single sided panels with carbon ink keypads. To avoid
> going double sided, or using multiple jumpers, we used the same carbon
> ink as conductor traces over the solder mask. No reliability or yield
> issues to date.
>
>
>______________________________ Reply Separator
>_________________________________
>Subject: Silver Ink Screen Print.
>Author: [log in to unmask] at internet
>Date: 11/14/96 9:01 AM
>
>
>Does anyone have any experiencies or information relating to "Silver Ink
>Screen Print" (or any other form of screen printed conductors).
>
>We have a situation where we have a number of PCA designs which have only
>a few minor modifications required. These will be picked up at the next
>CAD revision, but in the mean time, we would like to investigate
>screen printing additional connections accross the boards, without the
>need to hand wire.
>
>Any comments are appreciated.
> ________________________________________________________________________
> | [log in to unmask] David Tandy. EDA Specialist. GenRad ADS. |
> | Tel: (+44) 161 491 9191 Orion Business Park, Bird Hall Lane, |
> | Fax: (+44) 161 491 9292 Stockport, Cheshire, SK3 0XG, England. |
> |________________________________________________________________________|
>
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