Technetters,
In our BGA reballing services we are finding a high percentage of components
with serious dewetting and/or non-wetting on the component pads after board
removal.  These components have not been deballed with vacuum tools or
solderwick as evidenced by the large icicles on pads surrounding some of the
defective pads.

We are seeing this problem on BGA's from many different sources and are
beginning to see a trend which concerns us.  Our evidence suggests that the
failure mechanism is between the solder ball and the component rather than
between the ball and the board.

My question's are:

1.  If you have removed BGA's from the board do you see the same phenomenon?
2.  Upon removal from the board, do you believe that a component should ever
be left with a "bare pad" (no solder bump and no icicle) ?
3.  If a component can exhibit this effect and not be a "defective
component" then what mechanism would cause such an effect?
4.  Do you see "bare pads" on the board after desoldering the BGA from the
board?

Please help!

Russ Winslow
Six Sigma
1940 Concourse Drive
San Jose, CA  95131

(408) 526-1350
[log in to unmask]
http://www.sixsigmaservices.com

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