How to Measure Creepage Clearances

Hi

you can try CLASS in the "Matrix-mode"

One for the +15V net and one for +5V net

than you can go higher step by step the Clearence till the Error-Message in the DRC

CLASS 2 TEST5V ; CLASS 3 TEST15V 2:0.4mm

CHA CLASS 2 click the +5V-Net

CHA CLASS 3 click the +15V-Net

DRC

best regards,

Hans Sorgatz

Hi Hans,

Thanks for the tip, I'll give this a shot. To be honest, I've never really understood how the class matrix stuff worked or what it was used for. Tracking down all the places to put the nets will the hard part. But, maybe it won't be so bad if this can give me the info they need.

Regards,

Bob

Bob Starr schrieb:

I have a client that is working to get a PCB through UL

certification. I need some way to measure the minimum clearance

between any two nets. In other words I might need to know the minimum

clearance between any two traces/polys (eg, whats the min clearance

between +15V and +5V? for example).

That's not /exactly/ true. You don't need to (numerically) know the

minimum distance, you just need to make sure that you don't fall below a

specified minimum distance anywhere on the board.

However, that makes using CLASS (as already suggested) the perfect

solution. Simply enter your minimum distance requirements in the matrix,

assign the nets to the proper classes and run DRC. If DRC does not

complain, your layout is compliant.

The matrix is simple to use: you just specify the minimum distances for

signals within the same class and between their own and all other classes.

These distance requirements are also used by polygon calculation, so you

don't need to check them explicitly - provided you take care of using

different RANKs where needed.

Final word: enter slightly too large distances in the CLASS distance

matrix to provide for manufacturing tolerances in the production.

Tilmann

I found the following in the manual and trying to figure this out between the DRC clearance matrix:

Clearance between net classes

If a clearance is given in the form number:clearance, it defines the minimum clearance between signals in this net class and signals in the net class with the given number. The command

CLASS 3 1:0.6mm 2:0.8mm

defines a minimum clearance of 0.6mm between signals in net classes 1 and 3, and one of 0.8mm between signals in net classes 2 and 3. Note that the numbers in number:clearance must be less than or equal to the number of the net class itself ('3' in the above example), so

CLASS 3 1:0.6mm 2:0.8mm 3:0.2mm

would also be valid, whereas

CLASS 3 1:0.6mm 2:0.8mm 3:0.2mm 4:0.5mm

would not be allowed.

A clearance value of '0' between two net classes means, there is no specific value. Then the higher value of the participating net classes will be used.

Bob Starr schrieb:

I found the following in the manual and trying to figure this out

between the DRC clearance matrix:

.....

Why don't you simply enter CLASS and then expand the matrix with the

button in the lower right corner?

Tilmann

I asked a similar question not too long ago:

Would be nice to have as part of the measuring tool--Eagle already has the

capability built in, since it can run DRC rules.

http://www.eaglecentral.ca/index.php/m/167295/be3518208fb87eb707150ee1fad3d02e/#msg_167295

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I was able to get the info I needed in the DRC matrix mode, now we'll see what the UL guy says.

Thanks for the help, now I finally have a basic understanding of how to use matrix mode.

Best Regards!

Bob