Hi Gil,
We investigated a case where C4!!! Has intermetallic up to 15 microns! But the joints didn't fai
Regards,
Vladimir
Sent from my BlackBerry 10 smartphone on the Rogers network.
Original Message
From: Zilber Gil
Sent: Thursday, May 19, 2016 10:54
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] Intermetallic and high temperature operation
Hi David,
Thank you for your prompt response. The paper I found is:
app.aws.org/wj/supplement/WJ_1972_11_s536.pdf
1.
So for the moment I can tell my boss that we can use the board at 100 deg c for years, unless we will find more data that will warn us.
Thank you and best regards,
Gil
From: David Hillman [mailto:[log in to unmask]]
Sent: Thursday, May 19, 2016 4:12 PM
To: TechNet E-Mail Forum; Zilber Gil
Subject: Re: [TN] Intermetallic and high temperature operation
Hi Gil - you hit on one of my soapbox topics so I have respond! What data source are you citing that shows 6 micrometers of IMC results in solder joint failure? And for the IMC, is it the Cu3Sn or the Cu6SN5 phase? The industry is constantly "reminded" that thick IMC is brittle and will cause a loss of solder joint integrity but where is the data? Everyone is in consensus that IMC phases have been shown to have brittle properties but when I push for hard data/investigations/studies, demonstrating failures due to excessive, thick IMC phase, the real root cause has always turned out to be an out of control or excessive, abusive soldering process - typically a soldering process most folks would say "ohh, I wouldn't do that with my soldering process". For a dwell temperature of 100C, I will grow approximately 5 micrometers of IMC ( combine Cu3Sn and Cu6Sn5 phases) in 1660 hours using the standard IMC equations for tin over copper (my calculations don't match the details you listed). There are multiple examples of electronic products in many different product use environments that easily exceed that time and operate at that temperature yet we don't see reports of product integrity data. Unless you have some nontypical variable for your product in its use environment (basically, a variation of Doug saying "it depends" but with less gray area), I don't believe you have a solder joint integrity concern. Don't get me wrong, I think its great that folks are looking at how much IMC phase is produced/found on their solder joints but I think we overstate the topic on most occasions.
Dave Hillman
Rockwell Collins
[log in to unmask]<mailto:[log in to unmask]>
On Thu, May 19, 2016 at 7:34 AM, Zilber Gil <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hello Technet`s,
As we know above 6 micrometers of intermetallic (CuSn) could cause failure due to brittle structure of the intermetallic. I found in some experiment that at 100 deg C after 32 days the intermetallic (CuSn from Sn-40Pb) grow in about 6 micron. Is it true? What should I do if the board should see 100 deg C for long time and what about >=90 dig?
Thanks,
Dr. Gil Zilber
Technologiest
Elta Systems Ltd.
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