Hi Dave,
As far as I remember I said it's a reverie for disaster. As you know intermetallics will grow over time and a starting point of 10 or so microns doesn't help.
I had several cases of failure (cracked intermetallics) after it grew up to 12-15 microns.
Does it happen all the time? I don't know
May be not, but the cases I had are good enough "argument" , at least for me.
Regards,
Vladimir
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From: David Hillman
Sent: Wednesday, September 16, 2015 22:44
To: TechNet E-Mail Forum; Vladimir Igoshev
Subject: Re: [TN] BGA Reworked Intermetallic
Hi Vlad - what data do you have that 10 micron thick layer of IMC results in the failure of the BGA? There is TONS of subjective comments in the published literature but no hard data of failures. As a basic materials engineering principle, IMCs are brittle but that specific material characteristic seems to be the only reason folks make statements that a "thick" IMC is bad. Should we work to keep IMC layers minimized? Absolutely but I don't believe, as technologists, we should keep propagating the myth about thick IMC layers without having published, reviewable data.
Dave Hillman
Rockwell Collins
[log in to unmask]
On Wed, Sep 16, 2015 at 9:38 AM, Vladimir Igoshev <[log in to unmask]> wrote:
10 microns thick layer is a perfect way for a disaster down the road :-).
There are no parameters for E-Ni, but the appearance of the interface and a P-enriched layer is important.
Vladimir
Sent from my BlackBerry 10 smartphone on the Rogers network.
Original Message
From: Victor Hernandez
Sent: Wednesday, September 16, 2015 10:11
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] BGA Reworked Intermetallic
On ENIG surface I don't see much of an increase in the IMC formation thickness. However, on Cu it is a different story. I have measured IMC formation greater tham 10 microns. Not sure of the below statement about E-NI parameter. Please explain!!!
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
Sent: Wednesday, September 16, 2015 8:12 AM
To: [log in to unmask]
Subject: Re: [TN] BGA Reworked Intermetallic
The "magic" Number should stay the same 1-3 micron but you'd also have to keep an eye on what happened to the layer of E-Ni underneath.
Regards,
Vladimir
SENTEC
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Original Message
From: Datacom - Juliano Ribeiro
Sent: Wednesday, September 16, 2015 09:09
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: [TN] BGA Reworked Intermetallic
Hi to all,
When we reworked the BGA, removed the component of the board and replacement another BGA, what's the intermetallic thickness ideal after the rework?
p.s: Our pcb is ENIG finished and the solder is Tin Lead.
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Juliano Bettim Ribeiro
DATACOM
ENGENHARIA DE PROCESSOS
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+55 (51) 8446-2135
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