Hi Dieter,
If it possible, I will appreciate sending me the C version of 7095 for
review. I have lot of experience with the BGAs mix technology  process and
have my own work process and profile temperature instructions so I can give
my remarks to the committee.
Reuven

On Sun, Mar 4, 2012 at 7:31 PM, Dieter Bergman <[log in to unmask]>wrote:

> Dear Raye,
>
> We are in the process of completing the "C" revision of IPC-7095. The
> topic in which you expressed an interest will be in the new document.
>
> I've attached the minutes of the telephone call last year in which this
> topic was reviewed and we agreed to add the explanations to the table as
> shown in the minutes. That information should give you some good advice and
> characterize the reflow profile that is recommended for the situation.
>
> I've just returned from the APEX meeting in San Diego and although we are
> in the Balloting process we have a few additional Technical comments that
> were resolved at the meeting. These comments were about adding some more
> information on the causes of voids in the solder joint. We have to go for
> another short circulation to get the committee approval before we publish.
> There were no additional comments on the section that references table 7-3.
>
> I hope this helps.
>
> Best regards,
>
> Dieter
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
> Sent: Thursday, March 01, 2012 2:11 PM
> To: Technet
> Subject: [TN] BGA Reverse Backwards Compatibility
>
> Hello TechNet Gurus.
>
> I have seen lots of discussion and studies on the reliability of using
> BGAs with SAC solder balls on an assembly with SnPb paste. Many people are
> interested in this topic because of backwards compatibility issues when
> SnPb BGAs aren't available. At the risk of oversimplifying a complex topic,
> I understand this can be successful using a backward compatibility thermal
> profile such as the one shown on Figure 8-20 of IPC-7095B to ensure
> complete melting of both types of solder. Of course we must take care that
> the profile does not exceed the temperature limitations of the SnPb paste.
>
> Is anyone aware of any study done on the reverse situation? That is, SnPb
> BGAs used with SAC solder paste and a SAC thermal profile? I would think it
> would be at least as reliable as the above situation. We definitely get
> complete melting and the temperature profile is correct for the SAC solder
> paste chemistry so we are not as concerned about holding a narrow process
> window.
>
> This is not just academic curiosity on my part. We have some prototype
> boards built with SnPb BGAs SAC paste, and SAC profile. They are not for
> sale to customers, but some of our engineers are of the opinion that any
> mixed process joint is suspect. I'd like to find some data on the topic.
>
> I hope everyone is enjoying Apex.
>
> Best regards,
> Raye Rivera
>
> QA Manager * Canoga Perkins
> 20600 Prairie Street * Chatsworth * CA 91311-6008
> 818-678-3872  * [log in to unmask]
>
>
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