PH,

Yes, the IPC-7351 specification is starting the ball rolling on a 3D
Modeling standard. 

What PCB Libraries has done to introduce this is making a dedicated layer to
illustrate the Maximum Component Outline with a 1 micron line that is used
for IDF export. The trick to this is to not put anything else on that
dedicated layer. No polarity marking, no text, no multiple lines, just a
single "Closed Polygon".

Taking it to the next level, the IPC-2581 will illustrate CAD library data
with the land pattern and the physical component superimposed. So if you CAD
tool has IPC-2581 import and 3D modeling, your new CAD library will contain
both entities. 

This needs to be done to insure correct land pattern data from the beginning
of the PCB design process and not preforming the current land pattern
verification before you go into fabrication. 

PCB Libraries is developing a backward land pattern calculator called
"IPC-7351 LandCheck". You import your CAD data ASCII format into this
program. Then you can select any part that you want to check and select a
component family for the part. A menu and a browser / viewer will appear and
allows you to enter the basic component dimensional data. The program
instantly tells you whether the land pattern meets IPC-7351 specification
and if not provides you a report that will inform you on what is wrong. 

This will also check component height. If the Height that you entered from
the datasheet does not match the Geometry Height built into the land pattern
an warning will occur. 

This program is fully funtional for PADS right now and PCB Libraries is
giving away free copies to PADS Users who register for the IPC-7351
Navigator Wizard. 

In the near future the IPC-7351 LandCheck will import Protel data and it
certianly will import IPC-2581 data. 

The LandCheck program was originally intended to verify your old legacy
libraries to allow you to clean them up to meet the IPC-7351 specification.

Tom H



-----Original Message-----
From: Protel Hell [mailto:[EMAIL PROTECTED] 
Sent: Monday, June 28, 2004 8:32 AM
To: [EMAIL PROTECTED]
Subject: Re: [PEDA] IPC-2581 & IPC-7351.

Tom,

Is anything being done to standardize 3D modeling for PCB layout? One thing 
I think Altium leads the pack on is closing the loop to mechanical layout 
(3D modeling). Protel is similar to PADS with the Z height but they have 
gone one better, you can map a 3D model to your library part so that you can

export  an IGES file that can be imported in your 3D modeling software. 
Unlike PADS it is not an cost add on, it comes standard with DXP2004. (DXP 
was extra $) So all those vendors that have models available can be used 
directly by Protel. You can view a model of the pcb assembly and print in 
Protel. very impressive. Sure, this can be done too on the mechanical end, 
but it works so much nicer when the PCB layout person specs the model. Nice 
to have one person make sure the schematic symbol, layout footprint, and 3D 
model are all mapped correctly. I guess what I'm wondering is if anybody is 
collecting 3D models of parts?

PH






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