After all the activity on this thread regarding the pros & cons of
press-fit connectors and their impact on the laminate structure etc,
etc... At the end of the day what we have is an ill-conceived PTH design.
Not knowing the details of this particular connector my assesment is that
the PTH should be about 32-35 mils as opposed to 22. Using a 22
mil hole on a lead of the described size is just poor design and out of
compliance with IPC recommendations. I expect the designers reluctance to
change the PTH size may be due to a high density pin pitch that does not
allow for a corresponding larger land area. We can only
speculate...
Denis Lefebvre, C.I.D.
Senior PCB Designer
Finisar Corporation
1308 Moffett Park Drive
Sunnyvale, CA 94089-1133
http://www.finisar.com
At 02:20 PM 2/5/2002 -0500, you wrote:
Phil,
I disagree that there is a fair comparison of configurations here.
There may
be a "coincidental sizing" only by happen chance. I get
the feel of the
original question being the "age ole" question of what size
round hole for a
square pin. When the diameter is over sized for the corners it is
to big
across the flats (especially true for rectangular pins; 55302 connectors
for
instance). In the preceding case of a 25 diag in a 22 hole the is a
problem.
The problem becomes large when it is not controlled. Press fit
connector
technology is very much controlled.
The "oops" configuration uses pin and body shape NOT intended
to be press
fit. The PTH diameter can and will fluctuate relative to
tolerance. The
installation of connector is anyone's guess.
The press fit connector technology have years of heritage in well
engineered
systems configuration. The PWB thickness, drilled hole, plating and
finish
are all mandated. The installation of pins and body are to a
precise
installation requirement. The pin itself has been engineered with
material
and config to ensure reliability.
At the end of the day I would fly on the press fit connector while the
other
configuration may work, more importantly it may not.
Boston Brad
781 858 0783
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