There has been lot of information going back and forth about IMC and Cu and Ni dissolution but this discussion may not have anything to do with what Juliano problem. I think in order to give Juliano useful information he has to first let us know what he means by "damage to the component pad". 

George 

----- Original Message -----

From: "Vladimir" <[log in to unmask]> 
To: [log in to unmask] 
Sent: Thursday, November 10, 2016 6:25:15 PM 
Subject: Re: [TN] Reflow Profile using HASL or ENIG 

And again, as long as a continuous layer of intermetallic is formed it's a good joint from the metallurgy point of view. A slight increase in temperature for ENIG wouldn't matter at all from that point of view. 

Regards, 

Vladimir 

Sent from my BlackBerry 10 smartphone on the Rogers network. 
Original Message 
From: Stadem, Richard D. 
Sent: Thursday, November 10, 2016 17:19 
To: [log in to unmask] 
Reply To: TechNet E-Mail Forum 
Subject: Re: [TN] Reflow Profile using HASL or ENIG 

And to go back to the original question, the same principles are true for selective solder dwell times and temperatures as they are for reflow. 
If a nickel barrier exists, a slightly longer dwell time in the liquid solder may be required to achieve a good IMF with the nickel, but if you attempt to use the same selective solder profile on a board with Immersion Tin as a final finish, the copper dissolution will be greater as there is no nickel barrier. 

-----Original Message----- 
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman 
Sent: Thursday, November 10, 2016 2:57 PM 
To: [log in to unmask] 
Subject: Re: [TN] Reflow Profile using HASL or ENIG 

Hi Vlad - If I care about the interface being formed between the solder and the board pad, I do care about the dissolution rates and their impact on the IMC formation. I wasn't talking about metal dissolution to the point of pad destruction, I was talking about the formation of IMC layer itself. 
Copper/tin IMC is inherently better than nickel/tin due to crystallographic details. Does that IMC difference have an impact on solder joint integrity in many product applications? No, but it doesn't mean I should'nt pay attention to it and understand it so when it does matter I don't neglect it. And yep, I keep an eye on Alloy 42/Kovar for the same reason. And I don't need to do a ton of changes for the reflow profiles because of the plating but we do stay knowledgeable. 

Dave 

On Thu, Nov 10, 2016 at 2:29 PM, Vladimir <[log in to unmask]> 
wrote: 

> ‎Hi Dave, 
> 
> You know that difference in the dissolution rates of Cu and Ni 
> shouldn't even be considered. Following that path, what would one 
> recommend for soldering to alloy 42 :-). 
> 
> Regards, 
> 
> Vladimir 
> 
> Sent from my BlackBerry 10 smartphon!e on the Rogers network. 
> Original Message 
> From: David Hillman 
> Sent: Thursday, November 10, 2016 14:50 
> To: [log in to unmask] 
> Reply To: TechNet E-Mail Forum 
> Subject: Re: [TN] Reflow Profile using HASL or ENIG 
> 
> Hi folks - lots of good comments, just one more to add: copper 
> diffuses faster than nickel so some folks increase their reflow 
> temperatures 5-10C and/or slow down the belt speed 3-6 inches per 
> minute. It isn't necessary to do this but it does have some good 
> metallurgical basis. Werner Englemaier used to advocate doing this 
> when a board finish involved nickel (Werner and I discussed this at 
> length, very fun conversations). I set my reflow profile based on the 
> board thermal characteristics and the solder paste material but being 
> aware of the plating metallurgy impacts (such as the gold embrittlement Wayne detailed) is always a good idea. 
> 
> Dave Hillman 
> Rockwell Collins 
> [log in to unmask] 
> 
> On Thu, Nov 10, 2016 at 1:33 PM, Jose A Rios <[log in to unmask]> wrote: 
> 
> > The reflow profile is typically not a function of the final finish 
> > of the pwb. If it is thats news to me. 
> > 
> > José (Joey) Ríos, Sr QA Engineer 
> > Mission Assurance 
> > Kavli Institute for Astrophysics & Space Research Massachusetts 
> > Institute of Technology [log in to unmask] <mailto:[log in to unmask]> 
> > (617)324-6272 
> > 
> > 
> > 
> > > On Nov 10, 2016, at 2:17 PM, Wayne Thayer - EXT < 
> [log in to unmask]> 
> > wrote: 
> > > 
> > > Those two finishes are fairly similar from a wettability 
> > > perspective, 
> > assuming the ENIG is done properly and that no contamination or 
> significant 
> > oxidation occurs. 
> > > 
> > > If you are putting down some high-Au parts, such as leadless 
> > > ceramic 
> > packages, then the reduction in solder volume will make joint 
> > embrittlement/stalled flow (due to AuSn being formed) more likely, 
> > so you may want to adjust stencil apertures if you have those parts. 
> > > 
> > > But profile should probably be good. Might be able to reduce time 
> > > above 
> > liquidus slightly to reflect the fact that with ENIG there is no 
> > oxide to strip. 
> > > 
> > > Wayne 
> > > 
> > > -----Original Message----- 
> > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Blair Hogg 
> > > Sent: Thursday, November 10, 2016 11:01 AM 
> > > To: [log in to unmask] 
> > > Subject: [TN] Reflow Profile using HASL or ENIG 
> > > 
> > > Hi Technetters, 
> > > 
> > > Would a reflow profile need to change based upon the finish of the 
> > board? If we switch from HASL to ENIG would we need to change any 
> > parameters? (I know, probably too broad of a question) 
> > > 
> > > Thanks! 
> > > 
> > > Blair 
> > 
>