Print Page | Close Window

Why PCB Libraries Uses Different Standards

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: PCB Library Construction Guidelines
Forum Description:
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3407
Printed Date: 23 Oct 2024 at 4:29am


Topic: Why PCB Libraries Uses Different Standards
Posted By: Tom H
Subject: Why PCB Libraries Uses Different Standards
Date 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



-------------
Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn


Print Page | Close Window