I don't remember seeing any answers to this?
Well, at the risk of repetition (and revealing senility)
We have been experimenting with Immersion silver with great success.
Our bare board vendor prefers it and doesn't charge extra.
Other vendors might charge extra for it because:
1) They don't have the line and have to send it out
2) They bought the line and are trying to pay it off
but this will change just like all new technology, the process itself
is less harsh and cheaper than ENIG, and of course is a nice
flat surface which beats HASL for fine pitch and BGAs.
Our assembler thought it was Tin at first and had some problems,
but as soon as they discovered it was silver they adjusted their paste
or something and we have had no problems since, so you might want to
notify them what you are doing.
The only statement I would disagree with you on is the shelf life.
I have a bare board here that has been sitting on my desk for about
8 months and it is visibly tarnished. Our tech says it is still perfectly
solderable but tarnish makes me nervous.
In summary I would highly recommend you trying the new finish as
long as your bare boards don't sit around for months before you
assemble them.
Jack
|---------+---------------------------->
| | "Brooks,Bill" |
| | <[log in to unmask]
| | > |
| | Sent by: |
| | DesignerCouncil |
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| | ipc.org> |
| | |
| | |
| | 09/25/2003 03:19 |
| | PM |
| | Please respond to|
| | "(Designers |
| | Council Forum)"; |
| | Please respond to|
| | "Brooks,Bill" |
| | |
|---------+---------------------------->
>------------------------------------------------------------------------------------------------------------------------------|
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|To: [log in to unmask] |
|cc: |
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| Subject: [DC] Silver Immersion for Fine Pitch? |
>------------------------------------------------------------------------------------------------------------------------------|
Caterpillar: Confidential Green Retain Until: 10/25/2003
Retention Category: G90 -
General
Matters/Administration
I have just attended a meeting of the IPC Designers Council where the
subject of finishes for PCB's came up and it was revealed that Silver
Immersion seems to have great benefits for assembly, shelf life,
solderability, rework, etc...
Can anyone give me their experiences with the process and its benefits and
down sides? Have you personally used it, how long, what sort of problems
have you seen, what are the cost issues?
Best Regards,
Bill Brooks
"Politics is more difficult than Physics" - Albert Einstein
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