Dear All,
 
Recently, I was tasked to take over the x-ray imaging for the BGAs after the PCB has been assembled. Since I am doing the X-ray and curiosity get better of me, I scan through the rest of the components mounted on the PCB. Hey Presto! I saw solder voids which should not be there at all. What surprise me is that all these solder joints exhibit good fillets and wettability acceptable by the IPC standard for castellation and gull-wing packages. I am surprise to see solder voids as large as the width of the component leads are observed. Some of the solder joints even have multiple solder voids of various degree in diameter per solder joint. There is a 4-pad component that particularly have all 4 pads full of solder voids per pad and some of the voids >25%. As these assembled PCB has yet went through ESS, I am not sure whether I will be seeing any fallen parts, not to say any potential failure when they are delivered to our customer much later.
 
As it is a norm to have only BGAs x-ray to assess the solder workmanship, have I open up the 'Pandora box'?
 
 
Thanks and Regards,
~ Wee Mei ~

________________________________

From: TechNet on behalf of Inge Hernefjord
Sent: Thu 9/22/2011 2:47 AM
To: [log in to unmask]
Subject: Re: [TN] large parts falling off finished surface mount board assemblies



>
>
> I understand that this is of interst for some non-experts, so I add some
> more pictures on DIG this time. You can see the microstructure as a function
> of time in the autocatalytic bath.I have borrowed the photos from Uyemura,
> which we used a lot.
>
>  I have much better images done by myself. Will send to Dr Gregory if I
> find them.
>
> So, 4 more images offline to you Carl.
>
> (I'm always wondering why so few people are interested in the surface
> microstructure.)
>
> Inge
>


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------