Hi Kerry,

Please also check the alignment of BGAs prior to reflow. Misaligned BGAs
have cracked at the package side if the package is mask defined and PWB
side is etch defined. Contact area of ball to pad is narrower at the
package side due to mask defined pads. Please see attached image, or we can
put it up on the website.



At 12:09 PM 6/13/2005 -0400, Kerry McMullen wrote:
>Hi Technetters,
>Looks like we might have solved our BGA intermittent.  Two boards were
>accidently dropped from  a height of 12" (off a tray).  The (4) 1028 ball
>BGAs popped off both boards!  What is really interesting is that all the
>balls stayed on the boards, not on the device substrate.   Any idea what
>would cause this?  I know that you normally need a hammer to get a BGA off
>the board (unless you have an SRT).  The device sees about 205 C at peak.
>
>Thanks in advance?
>Kerry
>
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Thank-you

Mumtaz

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