...and a good image processor is VERY much worthful!
/Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Bruce Tostevin
Skickat: den 15 april 2008 18:48
Till: [log in to unmask]
Ämne: Re: [TN] Guidelines for setting voltage and current when viewing BGA
x-rays
Joe,
Early on when we acquired our present x-ray, we did some
characterization studies. We found that in general, for our machine,
voids were most accurately and repeatably measured if the voltage was
set so that the pcb etch patterns were still distinctly visible in the
background. Too little voltage, they are dark and indistinguishable,
too much and they're bloomed out. Overall for our machine, this has
worked well. There are still those occasional 2D x-ray vs. 3D (5 DX)
disagreements that require more focused effort (I couldn't resist the
pun.) to resolve. Overall though, we encounter very few borderline
situations where the x-ray setting alone is the difference between
go/no-go for a part.
We just revisited this issue, using a scrapped assembly with multiple
voids. It was examined on our in-house 2D and 5DX, and another high-end
x-ray machine we have access to. Images were captured at multiple
settings on each unit. Afterward, we cross-sectioned the sites to
measure the exact size of those voids and saw how they correlated with
different machines and settings.
Bruce Tostevin
Benchmark Electronics
Hudson, New Hampshire
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko
Sent: Monday, April 14, 2008 3:46 PM
To: [log in to unmask]
Subject: [TN] Guidelines for setting voltage and current when viewing
BGA x-rays
All,
Properly setting the voltage and current values on an x-ray machine seem
to be critical in correctly viewing BGA solder connections. To high or
to low will distort the x-ray image. I know that to high of a voltage
results in a phenomenon know as "voltage blooming".
I am looking for some general guidelines on setting a x-ray machine
voltage and current when viewing BGA solder connections so a potential
void can be correctly determined, measured, etc.. Thanks all.
best regards,
-joe
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