IPC Class 1 vs. Class 2 vs. Class 3: What Is the Difference?
Oct 09, 2026
IPC standards sort electronic products into three classes. The class decides how strict the acceptance criteria are.
The same solder joint can be acceptable for Class 1, acceptable for Class 2 and a defect for Class 3.
Class 1: General Electronic Products
Class 1 products need to work. Appearance and long service life are less important.
Examples include some consumer products, toys and simple devices where a failure is an inconvenience, not a safety issue.
Class 2: Dedicated Service Electronic Products
Class 2 products need continued performance and extended life. Uninterrupted service is desired but not critical.
Examples include communications equipment, business machines and many industrial controls. Most commercial electronics are built to Class 2.
Class 3: High-Performance Electronic Products
Class 3 products must work every time, on demand. Downtime cannot be tolerated, and the operating environment may be harsh.
Examples include aerospace, defense, life-support medical equipment and other critical systems.
Class 3 has the tightest criteria, such as more solder fill, stricter placement and fewer allowable anomalies.
Who Decides the Class?
The user (the customer) decides the class, not the manufacturer or the inspector.
The class should be called out on the drawing, purchase order or contract. If it is not, ask. Building or inspecting to the wrong class is a common and expensive mistake.
Can One Product Mix Classes?
Yes. A customer can specify Class 3 for some features and Class 2 for others, as long as it is documented.
Some programs also add requirements on top of Class 3, such as the Space Addendums for space and military hardware.
Why This Matters for Certification
IPC-A-610, IPC/WHMA-A-620 and IPC-A-600 all use the three classes.
Certification exams test whether you can apply the right criteria for the right class. Knowing the class system is one of the first things every CIS student must master.
