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October 2011

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Subject:
From:
Bob Landman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bob Landman <[log in to unmask]>
Date:
Sat, 22 Oct 2011 12:43:50 -0400
Content-Type:
text/plain
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text/plain (132 lines)
Fabian,

I would not jump to the conclusion it's a fab problem unless all electronic issues have been ruled out.  You say the SDRAM quits talking to the FLASH at -20C.  I don't understand that statement.  Memory doesn't talk to memory, the processor reads and runs code from the FLASH and writes and reads SDRAM.   Can the processor run at -20C?  If so then the next question is can the processor read and write to SDRAM?  Anything stuck on the data bus or memory bus (any other parts like ADC or DAC or display... ) can have a stuck bit.  An electronics tech should be able at -20C to tell which data or memory line or read/write line does not toggle when the test program exercises the lines.
That will point you to which part (could be the processor) is not working correctly. 

Just my 2 cents.

Bob Landman
H&L Instruments

Sent from my iPhone

On Oct 18, 2011, at 12:30 AM, Fabien Guizelin <[log in to unmask]> wrote:

> Bob,
> 
> Thanks for the prompt support.    Some more info :
> On failed PWA, the communication between SDRAM and FLASH stops at -20oC.   The units boots and hang or just refuses to boot.   Once temperature reaches back -10oC, the unit operates again.
> Dye&pry showed potential poor joints on the balls but nothing conclusive.
> We conducted EDX on both failed PWA and fresh PCB.  Both showed P-content 0.5% above IPC specs.
> 
> Black-pad originates from high Phosphorous content.   But, how severe is 10.4%wt P-content ?
> 
> Regards,
> Fabien
> 
> 
> From: Bob METCALF [mailto:[log in to unmask]]
> Sent: Tuesday, October 18, 2011 10:07
> To: TechNet E-Mail Forum; Fabien Guizelin
> Cc: [log in to unmask]
> Subject: Re: [TN] High Phosphorous content on ENIG PCB
> 
> Fabien,
> 
> It would be helpful to understand the nature of the failure. You mention it was a low temp failure. I don't understand what the failure is. Could you please expand on this? As far as the P content being slightly about 10%, assuming it is a mid to high phos nickel, I wouldn't expect a problem, but not knowing what has failed it would be difficult to speculate.
> 
> Regards,
> 
> Bob Metcalf
> Western Regional Manager
> 
> Atotech USA Inc
> 1750 Overview Drive
> Rock Hill, South Carolina 29730 USA
> 
> Mobile: 714-334-7667
> e-mail: [log in to unmask]
> Internet: www.atotech.com<http://www.atotech.com/>
> 
> Managing Director: Kuldip Johal
> 
> This e-mail and any attachments hereto are business documents of Atotech USA Inc. and may contain CONFIDENTIAL OR PROPRIETARY BUSINESS INFORMATION.  Unauthorized disclosure and/or use of information contained in this e-mail are prohibited.  If you are not the intended recipient, you should dispose of it and not use, disseminate or copy this message or any other files transmitted with it.
> 
> [cid:[log in to unmask]]
> 
> .
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> From:        Fabien Guizelin <[log in to unmask]>
> To:        <[log in to unmask]>
> Date:        10/17/2011 05:42 PM
> Subject:        [TN] High Phosphorous content on ENIG PCB
> Sent by:        TechNet <[log in to unmask]>
> ________________________________
> 
> 
> 
> Hi all,
> I am facing a PWA failure at low temperature.  An EDX analysis revealed a P-content of 10.4%wt which is outside the IPC-4552 1.2.1 specifications (7-10%).   The PCB has an ENIG finish.
> Could I be facing black-pad ?
> How severe is the 0.4%wt additional Phosphorous content ?
> Regards,
> Fabien
> 
> 
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