Yes, a reason . . .
Ignorance?
Knowledge?
Marketing?
Science?
Yin
Yang
If we only understood the laws of balance.
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of WEEKES, MICHAEL
> HS-SNS
> Sent: Wednesday, April 17, 2002 10:17 AM
> To: [log in to unmask]
> Subject: Re: [TN] Immersion Silver
>
>
> There must be some reason why less than 3% of the world has moved toward
> immersion silver. Why doesn't HASL or NiGold work for your application?
>
> Mike
>
> -----Original Message-----
> From: Jack C. Olson [mailto:[log in to unmask]]
> Sent: Wednesday, April 17, 2002 7:39 AM
> To: [log in to unmask]
> Subject: Re: [TN] Immersion Silver
>
>
> The PCD magazine list went down before I could get an
> answer to this question, does anyone have experience
> with silver and contact switches?
>
> ==============================================
>
> Most sources say a silver surface will not be solderable
> after a month or so unprotected. (Even in a baggie it will
> be okay a year later?)
> Anyway, you say it is good for switches, which would solve
> some of our hard gold plating problems.
>
> But I would think the "unsolderability" of the aged silver
> surface (unprotected in the unit and tarnished?) would
> affect the reliability of the switches, wouldn't it?
>
> Jack
>
>
>
>
>
>
> Rob Mongey <[log in to unmask]>@freelists.org
> 4Apr2002 06:08 AM
>
> Please respond to [log in to unmask]
>
> Sent by: [log in to unmask]
>
>
>
> To: [log in to unmask]
> cc:
>
> Subject: [pcdlist] Re: Immersion Silver
> Retain Until: 05/04/2002 Retention Category: G90 - Information and Reports
> Caterpillar Confidential: Green
>
>
>
> Hi all,
> Good to see Immersion Silver is starting to take off. We've
> been using
> it
> in here for about two years, and it is now our prefered board finish (We
> get silver finish unless we specify differently.) More common useage will
> mean that maybe more Far Eastern shops will start supplying it.
>
> We started to use Silver because it is so adaptable to what we need
> our
> PCB surface finish to do, namely:
>
> 1. Good solderability. (Silver excels at this, ask any vendor).
> 2. Flatness for fine pitch SMT. (Silver is as flat, if not flatter than
> Gold)
> 3. Mechanical strength for carbon pill switch contacts / Elastomer
> contacts. ( Flash Gold is weak, and hard Gold gives SMT solderability
> problems)
> 4. Stability for compression power contacts. (We have power
> contacts on our
> PCBs that mate to battery contacts via a spring compression. We found that
> the nickel under gold can cause problems with electrochemical migration
> toward our battery contact.)
>
> Immersion silver is the most suitable choice that can do all four. I'd use
> gold as an alternative, but we'd have to compromise our designs somewhat.
>
> We specify our Silver finish as 0.1 Microns Min to 0.2 Microns Max, over
> bare copper. Anyone else do it differently? Or do we trust our
> board shops?
> :)
>
> Regards,
> Rob Mongey.
> CAD Technician.
>
> Robert Mongey <[log in to unmask]> Tel : +353 (0)91 774300
> Bio Medical Research Direct : +353 (0)91 774338
> BMR House, Fax : +353 (0)91 774302
> Parkmore Business Park West, Mobile : +353 (0)87 2485262
> Galway
> Rep of Ireland.
>
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