IPC Class 2 VS Class 3: The Different Design Rules

As a circuit board manufacturer, designers often ask us about the difference between IPC Class 2 and Class 3. Class 1 does exist although we rarely produce boards that fall into this classification. Most of the times, even if the end-use of the product only requires Class 1. We will make it Class 2 just to ensure a better performance. This article will help you understand the different design rules for IPC Class 2 and Class 3 circuit boards.

There are four IPC classifications. Class 1 is assigned to general electric boards with a limited life and a “simple” function, such as the ones you can find in remote controls. Class 2 is for dedicated service electronic products. This means that you expect the board to have an extended life so you can place it in a television, a computer, or an air conditioner. Class 3 PCBs are tighter in tolerances as opposed to Class 1 and Class 2 boards. John Perry, Director of Printed Board Standards and Technology at IPC, explained:
“Class 3 includes products where continued high performance or performance-on-demand is critical, product downtime cannot be tolerated, end-use environment may be uncommonly harsh, and the product must function when required.”
These circuit boards are highly reliable. They are used to achieve high performances in the military or in medical, for instance. IPC-6012DS Class 3A includes space and military avionics. It is the highest class for printed circuit boards.
Class 1 – General electronic products
Class 1 boards are assigned to general electronic boards with a limited life and a simple function. This class includes most typical everyday products. The class 1 boards allow various cosmetic defects as long as it doesn’t affect the functioning of the board. The reliability of the product isn’t a critical factor in these types of boards. For instance, they can be found in TV remote controls, LED lights, kids’ toys, etc. They are the most inexpensive boards to manufacture in the industry but they come with a limited life expectancy. 

Class 2 – Dedicated service electronic products 
Class 2 boards have higher reliability and extended life. They follow more stringent standards than class 1 but allow some cosmetic imperfections. 
Here, uninterrupted service is preferable, but not critical. The class 2 products aren’t exposed to extreme environmental conditions. The board is expected to run continuously but its operation is not extremely critical. These kinds of boards are implemented in your laptops, smartphones, tablets, communication equipment, etc.

Class 3 – High-performance electronic products
Class 3 boards must provide a continued performance or performance on demand. There can be no equipment downtime, and the end-use environment may be exceptionally harsh. High levels of inspection and testing are performed on these boards with stringent standards. This makes the class 3...