Richard,
we have seen so many microcracks start at the edge of the defined 
soldermask, that we do only non-defined boards. One thing I don't 
understand: how can the small percentage of the thin soldermask cause damage 
to the much bigger area of the solder ball, especially when the solder is a 
little 'flexible' (I know W does not like the word)? It does not make sense 
to me.
/Inge


----- Original Message ----- 
From: "Stadem, Richard D." <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, September 17, 2009 7:49 PM
Subject: Re: [TN] fractured SJs due to soldermask compression


> Werner,
> What I am trying to say is that issues of ground plane configuration will 
> probably not lead to a reliability issue directly, unless they cause 
> issues during reflow of the BGA. But if the ground pour is done using 
> soldermask-defined pads, the soldermask-defined pads can lead to premature 
> failure of the SJ. My understanding (gained from a direct question I asked 
> you in your class) was that the soldermask can constrict the solder during 
> CTE expansion and contraction. Did I not understand you correctly?
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
> Sent: Thursday, September 17, 2009 12:32 PM
> To: [log in to unmask]
> Subject: Re: [TN] fractured SJs due to soldermask compression
>
>
> Hi Chris,
> First, never heard of "fractured SJs due to soldermask compression during 
> cyclic operation"—solder mask is much too soft and too thin; now, if you 
> talk encapsulants that is a different story.
> Second, "all of the other issues pale in the face of fractured SJs due to 
> soldermask compression during cyclic operation"—even if it were an issue, 
> a failure is a failure is a failure—'nough said.
> Werner
>
>
>
>
>
>
>
> -----Original Message-----
> From: Chris Ball <[log in to unmask]>
> To: [log in to unmask]
> Sent: Thu, Sep 17, 2009 1:07 pm
> Subject: [TN] fractured SJs due to soldermask compression
>
>
>
>
>
>
>
>
>
>
> Hello,
>
> Starting a new branch here.
>
> "All of the other issues pale in the face of fractured SJs due to
> soldermask compression during cyclic operation."
>
> Is this concern specifically for BGAs, or the same for any soldermask
> defined pad, even including selectively waved through-hole (PbFree)?
>
> Thanks,
> -Chris
>
>
>
>
>
>
>
> This e-mail message is intended only for the use of the intended 
> recipient(s).
> The information contained therein may be confidential or privileged, and 
> its
> disclosure or reproduction is strictly prohibited.
> If you are not the intended recipient, please return it immediately to its
> sender at the above address and destroy it.
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily20halt or (re-start) delivery of Technet send e-mail to
> [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 
> for
> additional information, or contact Keach Sasamori at [log in to unmask] or
> 847-615-7100 ext.2815
> -----------------------------------------------------
>
>
>
>
>
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to 
> [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to 
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 
> for additional information, or contact Keach Sasamori at [log in to unmask] or 
> 847-615-7100 ext.2815
> -----------------------------------------------------
> 

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------