Re: gEDA-user: PCB lib.

[norwoods <norwoods@gbronline.com>]

for your information I include the following news release from ipc

norwood sisson


         IPC Releases IPC-7351 Library Generation
         Tools for CAD Land Pattern Design

*NORTHBROOK, Ill., March 4, 2004*--IPC Association Connecting 
Electronics Industries®, in conjunction with the International 
Electrotechnical Commission (IEC) and world electronics industry 
standard groups, have released library generation tools in support of 
the forthcoming *IPC-7351*, /Generic Requirements for Surface Mount 
Design and Land Pattern Standard,/ for CAD land pattern.

Consisting of a powerful array of calculator and viewer tools developed 
between IPC and PCB Libraries, the IPC-7351 library generation tool set 
introduces the following for CAD libraries:

  1. An intelligent land pattern naming convention, which will aid in
     the standardization of electronic schematic symbols for engineering.


  2. Zero component rotations to allow CAD land patterns to be built
     with the same rotation for the purpose of assembly machine
     automation.


  3. Three new application-specific land pattern geometry variations
     that support various levels of product complexity. This 3-Tier CAD
     library system will support the following variations for each
     device family:

         a. Least Environment Land Pattern for miniature devices where
         the land pattern has the least amount of solder pattern to
         achieve the highest component packing density.

         b. Nominal Environment Land Pattern for products with a
         moderate level of component density and providing a more
         robust solder attachment.

         c. Most Environment Land Pattern for high component density
         applications typical of portable/hand-held products and
         products exposed to high shock or vibration. The solder
         pattern is the most robust and can be easily reworked if
         necessary.

  4. A placement courtyard excess that has been redefined to
     accommodate the three land pattern geometry variations.


  5. Clear definitions for silkscreen and polarity marking sizes,
     copper to ink clearances and locations.


  6. Land pattern origins to aid pick and place machine automation.


  7. Incorporation of enhanced mathematical algorithms for determining
     pad sizes and spacing within the 3-Tier environment. These
     algorithms account for fabrication, assembly and component
     tolerances to calculate a precise land pattern.


  8. New 3D modeling for mechanical verification using maximum
     component outlines and maximum component height.

This array of CAD library generation tools complements the IPC-7351 
concept of defining those properties crucial for global standardization 
and future acceptance of a “One World CAD Library,” whose main objective 
is to achieve the highest level of “Electronic Product Development 
Automation.” Developed in conjunction with PCB Libraries, these tools 
include browsers for quick location of land patterns, viewers for 
accessing component data for parts within a CAD library and calculators 
for defining exact land pattern dimensions from user supplied component 
and process data through the application of IPC mathematical algorithms.

“It’s no surprise that many large firms spend millions of dollars 
creating and implementing their own proprietary standards for their own 
electronic product development automation, standards not openly shared 
with the rest of the industry,” noted *John Perry*, IPC’s technical 
project manager. “These library generation tools, which support the 
forthcoming IPC-7351, will aid in the elimination of massive duplication 
of effort that costs our industry millions of unnecessary man hours by 
introducing a new standard that will allow electronic firms to benefit 
from electronic product development automation.”

The IPC-7351, like its predecessor *IPC-SM-782A*, /Surface Mount and 
Land Pattern Design/, will provide the appropriate size, shape and 
tolerance of surface mount land patterns, while allowing for inspection, 
testing and rework of component solder joints. In addition, the new 
standard will provide updated surface mount design rules, addressing the 
complexity of land pattern design for increasingly higher density 
electronics. IPC-7351 is anticipated for release in May 2004.