Reply to: RE>Measuring QFP Lead Pitch
Hi Hal,
The easiest way to verify the pitch is to return some devices to your
supplier for a failure analysis. They can report back to you if there
are any pitch issues.
I have come across a similar issue with 0.4mm pitch QFP's. A method
which I am considering is to send the parts to a lab for CMM
measurements. In my case, the devices are mechanical samples.
A quick method for verifying the pitch on a few devices is to use an
LSM (if you have one). Alternatively, you can use one of your pick and
place machines for measurements (I know this is available on the
Panasonic MPAIII).
If you hear of other services to perform this, please let me know.
Hope this helps.
Charles Elliott
NPI Process Engineering
Newbridge Networks
[log in to unmask]
--------------------------------------
Date: 1997.06.04 4:00 PM
To: Charles Elliott
From: [log in to unmask]
Hi TechNet,
We're assembling a board with a QFP304, and are seeing a dimensional
mismatch between the leads and pads. The pitch of the leads appears to be
greater than that of the boards, almost reminiscent of when people made errors
in the metric to english conversion when designing footprints. The footprint
is
correct, I've calculated the center to center distance of all pads from the
Gerber
file, and the pitch is exactly correct (.5mm). My next step in the
investigation
is to measure some parts, and I am in search of someone who can pick parts
out of a waffle tray, perform lead inspection, and report on lead spacing,
sweep, etc. I would like to do this on a large enough quantity of parts to
get
some signifigant data, so I don't want to do this manually on an optical
comparator.
Does anyone perform this service, or know of someone who can? Please keep
in mind that I'll be measuring good parts, so ESD and moisture sensitivity
protection are still important to me.
Thanks in advance,
Hal Winslow
Manufacturing Engineer
SCI Systems
300 Technology Dr
Hooksett, NH 03106
(603) 628-4862
[log in to unmask]
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