Not only the sj need to study, majority of the Pb parts are having mold compound rated at lower reflow temp.  
--------------------------
Sent using BlackBerry


----- Original Message -----
From: Gumpert, Ben [mailto:[log in to unmask]]
Sent: Wednesday, September 26, 2012 12:49 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] Leaded Paste and Lead Free BGAs - Do they mix?

I don't get why people compare mixed process joints to Pb-free joints.

The way I see it, if you are using a SnPb process, it likely means that you aren't comfortable with the long term reliability of Pb-free solder joints for your product, which is due to the deficiencies in understanding of the Pb-free joint and how to test for long term reliability.

So if you don't know how to test for long term reliability in Pb-free, how do you rationalize using it as a comparison???

Is anyone else confused by this, or am I just mixed up?

Ben

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
Sent: Wednesday, September 26, 2012 12:05 PM
To: [log in to unmask]
Subject: EXTERNAL: Re: [TN] Leaded Paste and Lead Free BGAs - Do they mix?

In a past job I built some assemblies using lead paste and lead-free BGAs. Because the company was a CM I never did get any long term reliability information from our customer, but we used a lead-free profile and had no problems with ball collapse. 

I am very interested to see any information on the reliability of mixed process joints when the reflow profile is sufficiently hot to achieve complete mixing. The few studies I've read, most recently Richard Coyle's work presented at Apex, used thermal cycling and as I recall the mixed process joints performed as well or better than lead-free process. 

We are developing a product now using a BGA that is not available with tin-lead balls. Reballing would exceed the manufacturer's limit for number of heat excursions. So we seriously considered mixed-process, but in the end opted to go all lead free. The experience did leave me wondering how fact-based the mixed process concerns are. Does anyone have notable successes or failures to share?


Best regards,
Raye Rivera
 
 
QA Manager * Canoga Perkins * 818-678-3872  * [log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Tuesday, September 25, 2012 5:26 PM
To: [log in to unmask]
Subject: [TN] Leaded Paste and Lead Free BGAs - Do they mix?

Hi,

 

I have a customer using leaded paste with lead free BGAs. I think they want to have the balls NOT collapse for better optical inspection.

 

Sounds like a really bad idea to me but I have no explanation where I can say as why.

 

Can anyone make suggestions either way?

 

Thanks,

Bob K.



______________________________________________________________________
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] ______________________________________________________________________



______________________________________________________________________
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] 
______________________________________________________________________

______________________________________________________________________
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] 
______________________________________________________________________

---------------------------------------------------------------------
This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. Any use of this information by anyone other than the intended recipient is prohibited. If you have received this transmission in error, please immediately reply to the sender and delete this information from your system. Use, dissemination, distribution, or reproduction of this transmission by unintended recipients is not authorized and may be unlawful.

______________________________________________________________________
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] 
______________________________________________________________________