On 08:34 AM 2/04/2001 -0500, Ted Tontis said:
>Dave,
>         The sights that are going to be your test points have to fall on the
>test point grid. If they do not you get a test point violation. You have to
>move the pad or via to the 1 mill grid, this will correct the problem you
>are seeing.
>
>Ted
>
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
>Sent: Monday, April 02, 2001 5:33 AM
>To: [EMAIL PROTECTED]
>Subject: [PEDA] Finding & Setting Test Points

I have said before that this is a flaw in the testpoint finder.

The only testpoint requirement I am given anymore is a 100 mil separation ( 
75 mil in special cases for very tight layouts/fine pitch connectors etc).

I do not want a grid for my testpoint but rather wish to be able to define 
the minimum separation.  I can set up rules that check for separation and 
coverage but currently I cannot  have the finder choose locations that meet 
my separation rule.

In fact we no longer use the testpoint finder - all our testpoints are 
shown on the sch and each comes into the PCB as a single pad component 
(single layer pad 1mm round with a 5 mil wide arc radius 47.5 mil on a mech 
layer).  Almost all vias are tented on our boards - the testpoint component 
is used to open up the bottom mask of just those vias used as testpoints. 
The testpoint components (flipped to the bottom side) are then placed on 
existing vias or bottom side tracks as desired.  The mech layer arcs makes 
it easy to see any clearance violations as you place them instead of 
waiting for the DRC to tell you.

We rarely use SM pads (of components) as testpoints - only on small volume 
boards that will be tested by flying probe testers and when the layout 
prevents full test access with 100 mil spaced testpoints.

This method may look like more work but the schematic shows each testpoint, 
testpoints have designators and so labelling on the PCB is slightly easier, 
the density of testpoints across a board is a little easier to see (the 
mech layer arcs) and extraction of testpoint locations is a little easier 
for our contract manufacturers.

Ian Wilson


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