Hi 
I was pretty sure NPL had done work on Cu Dissolution rates. I've had a
quick check on my HD and can only find a reference to the possibility of
it being measured.
It would be worth checking their site.
Regards
Rex


Rex Waygood
Technical Manager

Hansatech EMS provides value manufacturing through engineering and
quality

Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
Dorset BH17 0RY
United Kingdom
Tel: 01202 338200
Fax: +44 1202 338202
DDI: 01202 338222


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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stewart McCracken
Sent: 02 February 2012 10:12
To: [log in to unmask]
Subject: [TN] Cu - dissolution and IMC growth rate
Importance: High

Fellow Technetters,

We are going to be involved in a project this year looking at rates of
Cu dissolution and IMC layer growth during soldering processes
(including rework).
At this stage, I would like to ask the wider community whether anybody
has or knows of "rules of thumb", or published data etc. which describes
rates of dissolution and rates of IMC layer growth?

A little more specifically, based on a SAC305 alloy system, and using an
Immersion Silver or OSP PCB finish, we are looking to develop our
understanding of the following points:

1. IMC growth (microns) for SAC305 solder as a function of time exposure
(seconds) above 230C 2. Cu dissolution (microns) for SAC305 solder as a
function of time exposure (seconds) above 217C 3. Does anyone work to a
defined critical threshold (in terms of max IMC thickness) above which
PCB functional integrity is considered to be undermined?
4. Does anyone work to a defined critical threshold (in terms of min Cu
thickness) below which PCB functional integrity is considered to be
undermined?
5. Are there IPC or other standards covering these items?

I would be extremely grateful for your input, and would be very happy to
share results of the experimental programme which we will undertake
later this year.

Thanks and kind regards,

Stewart

Stewart McCracken
MCS Ltd.
Centre House
Midlothian Innovation Centre
Roslin
Midlothian
EH25 9RE
U.K.

t. +44 (0)131 440 9090
m. +44(0)7711 541735
e. [log in to unmask]
w. www.themcsgroup.co.uk


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