Tim,
It really depends on what your test group requirements are, based on
quite a few things but one would be type of probe being used, even
if the tester is capable of smaller pads and spacing, also the level at
which a fixture
is made would govern that too.
But with a newer GenRad system I would believe you could go a bit smaller
than
.100 for pads, so as PCB designer you may want to question your test group
and call the MFG of the tester, I'm sure they will help your case.
Generally speaking we used .040 pad if round and only dropped to .035 if
square.
But I just did a board for a customer that wanted .060 pads. Yes a bit large
but
I did not know what there test capability was and could not find out any
different info,
I was handed an ICT test document and told to follow it.
But the spacing of these pads is also spcified, we try to space TP to TP at
.100 centers however on dense boards we went dowm to .075 next then .050
as an absolute min. The smaller the probe the sooner it wears out.
Bob
Robert M. Wolfe, C.I.D.
[EMAIL PROTECTED]
----- Original Message -----
From: "Tim Fifield" <[EMAIL PROTECTED]>
To: "Protel EDA Form" <[EMAIL PROTECTED]>
Sent: Tuesday, March 12, 2002 9:23 AM
Subject: [PEDA] Test point Pad Size


> Can anybody tell me what the recommended test point pad size to be used
with
> the GenRAD GR228xi in circuit tester is? I think were using a combo II
> board.
>
> Our manufacturing dept. wants me to use a 100 thou diameter pad which
seems
> quite excessive to me. I currently have a 35 thou pad.
>
> Tim Fifield
>

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