Hi, Mark,

Never heard of star-shaped pads, but I suspect that sharp points, like
other sharp points in engineering, tend to be focal points for stresses.
Given the eternal concern about BGA joint reliability, I doubt that they're
a good idea.

There are X-ray machines around that give a 45 degree view for any
direction, and these can help greatly with Z axis inspection. Otherwise try
to see if the fibre optics wizards have come up with a thin enough probe to
get in under the BGA and look at the joints that way. Such a probe would be
quite fragile, though, and probably quite expensive.

Peter



Mark Roslawski <[log in to unmask]>    16/10/2002 11:44 PM
Sent by: TechNet <[log in to unmask]>

Please respond to "TechNet E-Mail Forum."; Please respond to Mark Roslawski

              To:  [log in to unmask]
              cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
              Subject: [TN] Z-axis BGA solder joint verification ?








Dear TechNetters:

I have a customer that wants to know if there is any way of verifying the Z
axis solder joint on BGAs ?

He has a x-ray machine that he can see in x and y axis', but he can not see
in z-axis for good solder joint verification.

He thought about using a star type design pad landing as opposed to a
circle pad landing so he could see the solder flow into the points of the
star.  Has anybody done anything like this or does anybody have any
recommendations ????

Any and all input is appreciated.

Thank You


Mark Roslawski
VP Marketing

ThermalWorks
2910 South Oak Street
Santa Ana, CA. 92707

Tel.  (714) 540-8454 x166
Fax. (714) 540-1299

Email: [log in to unmask]

Web Sites: www.thermalworks.com
                   www.SDCcircuits.com
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