Immersion Ag Champaign voids
Aspandiar,Raiyo (Intel) "Voids in Solder Joints", SMTA Northwest Chapter
Meeting, September 21th 2005
Kirkendall voids in Cu3Sn
Chui T., Zeng K (Texas Instruments) “Effect of Thermal Aging on Board Level
Drop Reliability for Pb-free BGA Packages“, ECTC 2004, pp. 1256-1262
Mattila T. and Kivilahti J. “Reliability of lead-free interconnections under
consecutive thermal and mechanical loadings”, Mattila and Kivilahti, Journal
of Electronic Materials, Vol. 35, No. 2, 2006, pp. 250-256
Xu L. and Pang H. “Effect of Intermetallic and Kirkendall Voids Growth on
Board Level Drop Reliability for SnAgCu Lead-free BGA Solder Joint”, ECTC
2006, pp. 275-282
On Mon, 4 Dec 2006 09:10:52 -0600, Victor G. Hernandez
<[log in to unmask]> wrote:
>Can you share some of the reports that you mentioned,
>
>Victor,
>
>-----Original Message-----
>From: Leadfree [mailto:[log in to unmask]] On Behalf Of Liang Yin
>Sent: Monday, December 04, 2006 8:40 AM
>To: [log in to unmask]
>Subject: Re: [LF] black pad
>
>Black pad issue is not the only problem associated with the ENIG surface
>finish when use lead-free solder alloys. It has been reported that Cu
>content in the solder joints could cause sporadic brittle failure, also
>referred to as the "missing ball" problem. It seems to relate to the
>nature of the Cu-Ni-Sn intermetallics, both (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4.
>
>As to immersion Ag, there are some issues.
> (1) "Champaign void " on the solder/intermetallic interface, sometimes
>could be bad. This is the problem right after soldering.
> (2) "Kirkendall voiding" in the Cu3Sn intermetallic after aging. It is
>not a time zero problem, but develops with time and temperature. In the
>past 2 years, it has been a concern for soldering to Cu surface,
>including Cu-OSP, immersion Ag, immersion Sn and HASL.
>
>Liang Yin
>Process Research Engineer
>Advanced Process Lab
>Unovis Solutions
>Binghamton, NY
>
>
>On Thu, 30 Nov 2006 07:32:56 -0600, Stadem, Richard D.
><[log in to unmask]> wrote:
>
>>While I would be the last person to say anything positive about ENIG, I
>
>>do wish to point out that in particular applications it is the best
>>finish, but this is only in a very limited number of applications.
>>Having said that, I do know that some fabricators have been able to
>>control their processes such that they (their customers) never
>>experience either BP and/or BIF. But it is still my last choice of
>>surface finishes, with IAg being the first.
>>
>>-----Original Message-----
>>From: Leadfree [mailto:[log in to unmask]] On Behalf Of Graeme Stewart
>>Sent: Thursday, November 30, 2006 5:41 AM
>>To: [log in to unmask]
>>Subject: Re: [LF] black pad
>>
>>I have regarded Black Pad/Brittle Interface Fracture as inherent to the
>
>>ENIG system and no amount of process control by the PCB manufacturer
>>can eliminate it. The best explanation I seen for BIF is given in the
>>attached paper. I have observed the intermetallic variation between
>>defective and non-defective joints at both the PCB/ball interface
>>BGA/ball (were the BGA has used the ENIG process) as well as PCB
>>geometry influence.
>>We have not used ENIG on boards designs from this division for over 7
>>years now.
>>
>>Regards,
>>Graeme Stewart
>>
>>-----Original Message-----
>>From: Leadfree [mailto:[log in to unmask]] On Behalf Of SCHMIDT,
>>WOLF-DIETER - PFHO
>>Sent: 29 November 2006 08:19
>>To: [log in to unmask]
>>Subject: [LF] black pad
>>
>>Hello Gaby,
>>
>>a few weeks ago the research report on that topic, carried out by Andus
>>(PCB-manufacturer) and Fraunhofer Institute, was published. The result
>>based on technical analysis and a poll asking a lot of PCB manufacturer
>
>>as well as assembling companies showed that neither the type oc
>>chemistry (e.g. the chemistry supplier) nor the type of solder nor the
>>soldering process itself is the reason for black pad. The only
>>remaining root seems to be some inaccuracies during running the board
>>production process - mainly the chemistriy of cleaning and surface
>plating.
>>
>>The same information I received two years ago from Eric de Kluizenaar
>>(ex Philips Eindhoven).
>>
>>Best regards
>>
>>Wolf-Dieter Schmidt
>>-----------------------------------------------------------
>>THALES Defence Deutschland GmbH
>>Industrial Engineering
>>Land & Joint Systems
>>Ostendstrasse 3
>>D-75175 Pforzheim - Germany
>>-----------------------------------------------------------
>>Phone: +49 7231 15 3386
>>Fax: +49 7231 15 3390
>>mailto: [log in to unmask]
>>http://www.thalesgroup.com
>>
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