Steve,
The reason for the diamond pad was to see the pad against the ball
land/CGA pin/pad. Not sure if that makes since, what just said, but
they say it's easier to see the round pad of the BGA or CGA pin against
the pad on the board, different shapes. That my story and I'm sticking
to it. :-) I'm not 100% convinced this is a super great idea but I
really don't have enough information to go on yet... Thanks for your
input. I don't remember what eh X-Ray machine we have is, but it's fun
to use to look at bare boards sometimes! :-)
Later...
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Friday, April 21, 2006 10:56 AM
To: [log in to unmask]
Subject: Re: [TN] BGA and CGA pad questions.
Hi Scott!
I can't offer you any experience about using diamond pads with BGA's or
CGA's, because I've never seen it. Working in contract assembly and
being exposed to many different company design standards, I would say
that if diamond shaped pads really provided a benefit, I should have
seen it by now...but I haven't.
At my past employer, we had a FeinFocus Tiger 160, and I had no problem
seeing the pad-to-ball interface when doing an x-ray inspection. I'm
trying to understand what would be gained by having a diamond pad?
Kind regards,
-Steve Gregory-
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Scott Decker
Sent: Friday, April 21, 2006 12:40 PM
To: [log in to unmask]
Subject: [TN] BGA and CGA pad questions.
All,
I was talking with our Manufacturing engineer the other day and the
people that make the SMD re-work station tools, about the pads used for
both BGA's and CGA's. The vendor was saying that diamond pads, (square
on a 45') were better for X-Ray inspection because you can see the pad
verses the pin/ball better during the inspection of the solder joints.
The X-Ray manufacturer' says the same thing, but has anyone done it this
way yet? It sounds good to me, but does anyone have any practical
experience with the diamond pads? How do you figure size between round
to square, etc.? Is it just area calculations or flat side the same as
diameter, etc.? Paste Mask sizing, Solder Mask defined, (not my thought)
or just the standard oversize, etc.? These would be for high-reliability
applications and from what I understand, the CGA is better in that
respect. Any info would be great to hear. Thanks in advance.
Scott Decker
AKA: Padmasterson
Broad Reach Engineering CAE
Ph. 480-377-0400 Ext. 34
FAX. 480-968-4597
Tempe, AZ.
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