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. 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