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Design Guidelines to Build Error-Free IPC Class 3 PCBs

Headshot of Amit Bahl

Amit Bahl

Sierra Circuits

Our tips for your IPC Class 3 PCBs

IPC class 3 PCBs are generally implemented in high-performance products with little or no downtime. These boards must be fabricated without any defects, such as voids, solder deformation, or via barrel cracks to achieve high reliability. Class 3 circuit boards adhere to tight manufacturing tolerances that are defined by IPC-6012E standards.

The IPC-6012E document defines the specifications and performance requirements expected of a class 3 board. IPC-6012E has separate addenda for space, military, automotive, and healthcare industries. They set benchmarks for annular ring breakouts, drill size, pad diameter, plating thickness, voids, dielectric spacing, and solder joint acceptance.

Understanding these specs during the initial stage will reduce respins and turnaround time. You also need to understand if your manufacturer is capable of building a class 3 board. If the requirements are beyond the IPC specifications, then you can build it as agreed between you and the fab house (AABUS).

Being a designer, you need to have a good understanding of the DFM and DRC rules to avoid any failures that may arise during fabrication. To maintain signal integrity in class 3 designs, consider crosstalk, reflection, controlled impedance and EMI during the layout phase. For thermal management, you need to incorporate heat dissipation techniques such as thermal vias, thick copper traces (>3oz) to maintain the board’s functionality.

IPC class 3 PCBs are known for their stringent testing procedures like automatic optical inspection (AOI), flying probe testing (FPT), and micro-section analysis.

In this webinar, you will learn from our PCB design and manufacturing experts about the best practices to build class 3 boards.


What you’ll learn:

  • Differences between class 2 and class 3 PCBs
  • Design and layout considerations for class 3
  • Signal integrity prerequisites
  • Effective thermal management
  • DFM and DRC rules for class 3
  • Testing and inspection procedures: Micro-section analysis, AOI, and FPT
  • Fab and assembly notes


Presented by Amit Bahl

Amit has been in the PCB industry for 20+ years. He is the Chief Revenue Officer at Sierra Circuits. His passion is to empower tech companies to achieve their visions and change the world. Rockets going into space, self-driving cars taking up the streets, cancer-fighting medical devices, protecting the country, he’s ready to build any circuit board!

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Screenshot from Design Guidelines to Build Error-Free IPC Class 3 PCBs

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