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February 2012

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Subject:
From:
Inge Hernefjord <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Inge Hernefjord <[log in to unmask]>
Date:
Fri, 3 Feb 2012 23:38:19 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (264 lines)
Your statement is somewhat diffuse. However, what's clear is that both are
chemical terms.

1. Dissolution: The act or process of resolving or
dissolving<http://dictionary.reference.com/browse/dissolve>
into parts or elements.

2. Diffusion: The spontaneous intermingling of the particles of two or more
substances as a result of random thermal motion

Inge

On 3 February 2012 22:56, <[log in to unmask]> wrote:

> Well it is a chemical term.  We have dis solution over here and dat
> solution over dere..................
>
> Somebody help me......................
>
> Doug Pauls
>
>
>
> From:        Inge Hernefjord <[log in to unmask]>
> To:        <[log in to unmask]>
> Date:        02/03/2012 02:55 PM
> Subject:        Re: [TN] R: [TN] Cu - dissolution and IMC growth rate
> Sent by:        TechNet <[log in to unmask]>
> ------------------------------
>
>
>
> Dissolution (why do we use that word?I prefer diffusion) of various metals
> in solder melts has been done for cent uries, so I have nothing new. What I
> found unexpected was the mirror-like diagrams showing Gold, Silver, Copper
> and some others dissolution in Sn6040.  Probably following arrhenius's law.
> You must see it yourself, so I send it to Steve and his dino.
>
> I read some interesting facts in one of the ASTM Handbooks. "Handbooks" !1
> This one is so gross and heavy, that you need car lift. If you drop that
> volume, seismographs all around will jump.
>
> Inge
>
>
>
>
>
>
> On 2 February 2012 23:58, SALA GABRIELE <[log in to unmask]> wrote:
>
> > Hi,
> >
> > What I found on IPC Standards, just few paragraphs on
> > IPC-HDBK-001,(Dec-2000)
> >
> > 4.1.7.2 Intermetallic Layers
> > 4.1.7.2.1 Intermetallic Growth Rates
> >
> > As Dave says, plenty of information (Papers) are available about Copper
> > Dissolution phenomena and IMC behaviours at different temperatures and
> > Alloys. With Reflow,Wave and Rework Processes.
> > Also on web, if lucky, by googling you can find plenty of helpful infos.
> >
> > Regards
> >
> > Gabriele
> >
> >
> > -----Messaggio originale-----
> > Da: TechNet [mailto:[log in to unmask] <[log in to unmask]>] Per conto di
> David D. Hillman
> > Inviato: giovedì 2 febbraio 2012 23.02
> > A: [log in to unmask]
> > Oggetto: Re: [TN] Cu - dissolution and IMC growth rate
> >
> > Hi Stewart - I would recommend that before you launch into a SAC305
> copper
> > dissolution project that you investigate the published data as there has
> > been a tremendous volume of work in that area already. Sources in my
> > references include:
> >
> > - a number of papers presented in the IPC APEX and SMTAI conferences in
> > the 2005-2012 time frame
> > - NPL (Dr. Chris Hunt and team) did a great study on dissolution rate
> > - Craig Hamilton and the folks from Celestica have some great
> publications
> > on copper dissolution
> > - the NASA DoD report has copper dissolution data for SAC305 and SN100C
> > solder alloys (the report is on the web)
> >
> > Your question on "how thick can IMC get before we have cracking issues"
> is
> > a good question but the reality is that the number of IMC cracking issues
> > published can be counted on one hand. Using industry typical soldering
> > process, either tin/lead or leadfree solder alloys, you need to severely
> > abuse the process parameters to get into those types of situations.
> > Published data by Thwaites and Klein Wassink covers the IMC topic. There
> > is no IPC standards on copper dissolution or IMC thickness that I am
> aware
> > of.
> >
> > Good luck with the effort.
> >
> > Dave Hillman
> > Rockwell Collins
> > [log in to unmask]
> >
> >
> >
> >
> > Stewart McCracken <[log in to unmask]>
> > Sent by: TechNet <[log in to unmask]>
> > 02/02/2012 04:11 AM
> > Please respond to
> > TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> > Stewart McCracken       <[log in to unmask]>
> >
> >
> > To
> > <[log in to unmask]>
> > cc
> >
> > Subject
> > [TN] Cu - dissolution and IMC growth rate
> >
> >
> >
> >
> >
> >
> > 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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