Why PCB Libraries Uses Different Standards

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 PCB Libraries, Inc.
     contributes and studies all the world standards for PCB library part
     rules. We only use the best practices from every standard. Examples:
 
  IPC-7351B was the mathematical
      we used from 2005 – 2023 
  
   The mathematical model
       used manufacturing tolerances and negative solder joint goals to
       compensate for the manufacturing tolerances for side joints.
  
  Footprint Expert
      changed to the IPC-7352 mathematical model in May 2023 when it was
      released
  
   The mathematical model
       removed manufacturing tolerances and negative solder joint goals
   However, users can
       revert to IPC-7351B if they want to use the old format
  
  IPC J-STD-001 is used for solder
      joint goal guidelines. IPC-7351B and IPC-7352 guidelines for
      solder joint goals are too robust and do not adhere to J-STD-001 Standard.
      
  IEC 61188-7 Level B is used for
      the default Pin 1 orientation. 
  
   IPC-SM-782 was the
       first surface mount standard released in 1987 and ran for 18 years. This
       standard matched the IEC 61188-7 Level B. 
   In 2005 IPC release
       7351 and changed the Pin 1 orientation to Pin 1 Upper Left. 
   In 2007 IEC 61188-7
       Level B was released to revert to the original orientation in IPC-SM-782
  
  IPC-7351C is used for the
      footprint naming convention. 7351C was reviewed by the IPC Land Pattern
      Committee for 6 years. They approved the new naming convention, and we
      added it to Footprint Expert because it was superior to 7351B. Then IPC
      discontinued 7351C and never released it.
  IPC-7352 is used for the pad
      stack naming convention. 
  FED Volume 18 by Rainer Taube
      released in 2018 supported Proportional Land Dimensioning Concept. It
      differs from IPC mathematical model that uses min/max package dimensions.
      The FED recommends using Nominal Package Dimensions and hard coding the
      solder joint goals for Toe, Heel and Side. Do not use package tolerances
      when using this concept and create realistic solder joint goals approved
      by your assembly shop.
  Manufacturer’s
      Recommend Patterns are
      used for all non-standard packages and connectors

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Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Online Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Topic: Why PCB Libraries Uses Different Standards Posted: 05 Aug 2024 at 12:27pm
	PCB Libraries, Inc. contributes and studies all the world standards for PCB library part rules. We only use the best practices from every standard. Examples: IPC-7351B was the mathematical we used from 2005 – 2023 The mathematical model used manufacturing tolerances and negative solder joint goals to compensate for the manufacturing tolerances for side joints. Footprint Expert changed to the IPC-7352 mathematical model in May 2023 when it was released The mathematical model removed manufacturing tolerances and negative solder joint goals However, users can revert to IPC-7351B if they want to use the old format IPC J-STD-001 is used for solder joint goal guidelines. IPC-7351B and IPC-7352 guidelines for solder joint goals are too robust and do not adhere to J-STD-001 Standard. IEC 61188-7 Level B is used for the default Pin 1 orientation. IPC-SM-782 was the first surface mount standard released in 1987 and ran for 18 years. This standard matched the IEC 61188-7 Level B. In 2005 IPC release 7351 and changed the Pin 1 orientation to Pin 1 Upper Left. In 2007 IEC 61188-7 Level B was released to revert to the original orientation in IPC-SM-782 IPC-7351C is used for the footprint naming convention. 7351C was reviewed by the IPC Land Pattern Committee for 6 years. They approved the new naming convention, and we added it to Footprint Expert because it was superior to 7351B. Then IPC discontinued 7351C and never released it. IPC-7352 is used for the pad stack naming convention. FED Volume 18 by Rainer Taube released in 2018 supported Proportional Land Dimensioning Concept. It differs from IPC mathematical model that uses min/max package dimensions. The FED recommends using Nominal Package Dimensions and hard coding the solder joint goals for Toe, Heel and Side. Do not use package tolerances when using this concept and create realistic solder joint goals approved by your assembly shop. Manufacturer’s Recommend Patterns are used for all non-standard packages and connectors
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KoryJohnsonTek Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 03 Oct 2024 Status: Offline Points: 1	Post Options Post Reply Quote KoryJohnsonTek Report Post Thanks(0) Quote Reply Posted: 03 Oct 2024 at 10:12am
	Hi Tom. Thanks for the post. I'm not a constant follower of the site, but do check in on occasion. I'm a bit curious about 7352 not including manufacturing tolerances. Is there a backstory to that decision?