I don't know about other people, but if you read the soldering information
of IBM for ceramic BGA, you will find it there, reccommended for CGA too.
From what I heard, it is not so good for columns- I suppose that this is
because placement has to be done with applied force  and maybe if the
columns are nor perfectly aligned or the device is nor at 90*, they will
deform, causing shorts or break. We forgot to apply force the first time
(SRT has the option) and The results were not good, Don't forget that the
stencil is upside down and the bulk of paste is on the balls, with less
paste towards the circuit. Also, the stencilreccomendations are special,
balls with the same pitch but different dimensions get more or less paste
volume, as more or less of the ball is intruding the aperture.
Gaby
----- Original Message -----
From: "Earl Moon" <[log in to unmask]>
To: <[log in to unmask]>; <[log in to unmask]>
Sent: Friday, May 31, 2002 6:47 PM
Subject: Re: NTC - The Gregory's are a team now...


> I'm with you Gaby,
>
> Got to get the pumpkin shape when the balls squat. Very even ball shapes
in
> Xray verify this clearly as well as edge visualization. You know all this
> stuff so I wish you well and keep us all informed about the Genrad gizmo.
I
> like it. Has anyone else tried it, I wonder?
>
> Earl
>

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