Thank you everyone for your feedback. We’ve been using ENEPIG for a few years now with no issue, and it was just a thought that ran through my mind that I wanted to confirm.
I don’t doubt that there may be misinformation about using ENEPIG with lead-based systems. I typically stick with ENIG for lead-based and ENEPIG for Lead-free, but it’s based on a Uyemura study (yes I can provide) that found the ball pull test were better with the combinations of lead/ENIG and SAC305/ENEPIG. But in general context they weren’t bad all around under normal conditions. But if the lead/ENEPIG boards are subject to long durations of heat, intermetallic form resulting in reduce ball pull strength. Like anything, it’s understanding the end use environment.
Best,
-Jeffrey
Jeffrey A. Jenkins
Sr. PCB Staff Designer, CID+/CIT
L-3 Communications, Linkabit Division
Work: 858-552-9832
Email: [log in to unmask]<mailto:[log in to unmask]>
From: David Hillman [mailto:[log in to unmask]]
Sent: Thursday, September 17, 2015 5:45 AM
To: TechNet E-Mail Forum; Jenkins, Jeffrey A @ CSG - LINKABIT
Subject: Re: [TN] ENEPIG Question?
Hi Jeff - just some additional info for the discussion. Pd and Au act somewhat similarly in solder situations except for two big characteristics: (1) the dissolution rate of Pd in solder is orders of magnitude slower than Au; (2) the amount of Pd to cause solder joint embrittlement is lower than for Au (1% vs 3%). The good news is that the re-segregation of Au to solder joint interfaces that occurs in ENIG doesn't happen with Pd. The IMC phase that is the trouble maker is PdSn4 and it can result in solder joint failure under some conditions. Gold embrittlement is much more of an issue (the IMC phase is AuSn4) for the industry. Mike Wolverton, Raytheon, published a very good paper in the 2011 SMTAI Conference proceedings (session SUB3) that covers the topic well. The IPC-4556 specification on ENEPIG contains a weath of data in its Appendices. And one last comment, there is some misinformation running around the industry that ENEPIG is not compatible with tin/lead soldering process which is incorrect. Hope this helps.
Dave Hillman
Rockwell Collins
[log in to unmask]<mailto:[log in to unmask]>
On Wed, Sep 16, 2015 at 11:01 AM, Jenkins, Jeffrey A @ CSG - LINKABIT <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi All,
Quick question, with an ENIG finish, I know the gold dissolves into the joint and we solder to the Ni.
But what about ENEPIG? I'm assuming the Au will dissolve, but what happen with the Pd? Does it stay put or also dissolve into the joint?
Inquiring minds want to know.
Thanks,
-Jeffrey
Jeffrey A. Jenkins
Sr. PCB Staff Designer, CID+/CIT
L-3 Communications, Linkabit Division
Work: 858-552-9832<tel:858-552-9832>
Email: [log in to unmask]<mailto:[log in to unmask]>
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]<mailto:[log in to unmask]>
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
