Hi Rueven,

 

The photo is of the QFN, not the board. The QFN is matte tin finished...

 

Steve

 

From: Reuven Rokah [mailto:[log in to unmask]] 
Sent: Tuesday, April 23, 2013 11:37 AM
To: TechNet E-Mail Forum; Steve Gregory
Subject: Re: [TN] QFN Pad Corrosion?

 

PCBs finish are ENIG?

May be black pads?

Reuven

On Tue, Apr 23, 2013 at 8:12 PM, Steve Gregory <[log in to unmask]>
wrote:

Hi All,



I have another question about the QFN16 that I was talking about last
week. I was sent a photo of the bottom of one of the devices after it
had been removed from a failed board. It is here:



http://stevezeva.homestead.com/QFN16_Corrosion.jpg



It's pointing out a pad that seemed to have a lot of corrosion on it and
I was told that solder would not wet to it. I was asked what might cause
this?



My first thoughts are that the appearance might have been caused by the
rework when it was removed, and that a un-solderable intermetallic has
formed on pad  but I can't say that for sure. The part is finished with
matte tin when it is supplied. When a part is tin finished, they have a
barrier nickel plate beneath the tin right?



I don't have the part in front of me, I only got sent the photo. I was
asked what my thoughts were, so I thought I'd ask my TechNet friends
too... :o)



Thanks,



Steve Gregory


______________________________________________________________________
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]
______________________________________________________________________





 

-- 

	Best Regards,
	
	Reuven Rokah 
	   
	Mobile: 972-52-6012018
	Tel:        972-3-9360688
	Fax:          076-5100674
	<http://www.rokah-technologies.com/>
[log in to unmask]
	[log in to unmask]
	www.rokah-technologies.com <http://www.rokah-technologies.com/> 
	
	
<http://royiro.weebly.com/uploads/6/3/6/9/6369812/4511319.jpg?303> 
	This e-mail message is intended for the recipient only and
contains information which is CONFIDENTIAL and which may be proprietary
of Rokah Technologies. If you have received this transmission in error,
please inform me by e-mail, phone or fax, and then please delete all of
the original files and all other copies exist.


______________________________________________________________________
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] 
______________________________________________________________________