- 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
|