What is IPC Class II and Class III for PCB?

In the world of printed circuit board (PCB) manufacturing, not all boards are created equal. Depending on your application, your PCB may need to meet IPC Class II or IPC Class III standards — two of the most widely recognized quality classifications in the electronics industry. Understanding the differences between these classes is essential for making informed design and manufacturing decisions that balance performance, reliability, and cost.

At DQS ELECTRONIC, we specialize in manufacturing both IPC Class II and Class III PCBs, offering our clients certified quality, engineering support, and flexible production capabilities. In this article, we’ll break down the key differences between the two standards, their typical applications, and why partnering with us ensures your project is built to the right spec — on time and on budget.

What Are IPC Classes?

The IPC (Association Connecting Electronics Industries) defines three classes of electronic products based on their required reliability and performance:

• Class I: General consumer electronics with minimal reliability needs (e.g., toys, basic gadgets).
• Class II: Dedicated service electronics — products that require extended life and reliable performance, but not mission-critical operation.
• Class III: High-performance electronics — used in applications where failure is not an option, such as aerospace, military, and medical life-support systems.

Both Class II and Class III demand high-quality manufacturing, but they differ significantly in tolerance levels, inspection rigor, and cost.

IPC Class II: The Sweet Spot for Commercial and Industrial Applications

IPC Class II is ideal for applications that require good reliability and longevity, but not the extreme precision of Class III. These boards are commonly used in:

• Industrial control systems
• Telecommunications equipment
• Medical devices (non-life-support)
• Automotive infotainment
• Office and consumer electronics 

Key Characteristics of IPC Class II:

• Copper thickness: Minimum 18 μm in plated through-holes 
• Annular ring breakout: Up to 90° allowed if minimum spacing is maintained 
• Solder fill: Minimum 50% in through-hole leads 
• Inspection: Standard visual and electrical testing; minor cosmetic defects are acceptable if they don’t affect functionality 

This classification offers a cost-effective solution for products that need to perform reliably over time but don’t require the ultra-high reliability of Class III.

IPC Class III: Built for Zero-Failure Tolerance

IPC Class III is the gold standard for mission-critical applications. These boards must perform flawlessly under extreme conditions, and every aspect of their design and manufacture is held to the highest standards.

Typical applications include:

• Aerospace and avionics
• Military and defense systems
• Medical implants and life-support devices
• High-reliability automotive systems

Key Characteristics of IPC Class III:

• Copper thickness: Minimum 20–25 μm in plated through-holes 
• Annular ring breakout: Not permitted; minimum 1 mil internal, 2 mil external annular ring required 
• Solder fill: Minimum 75% in through-hole leads 
• Inspection: 100% inspection including X-ray, cross-sectioning, and thermal cycling 
• Documentation: Full traceability of materials and processes

Because of these stringent requirements, Class III boards are more expensive and time-consuming to produce — but they deliver unmatched reliability in critical environments.

Class II vs. Class III: A Quick Comparison

Why Choose DQS ELECTRONIC?

At DQS Electronic Group, we don’t just build PCBs — we build confidence. Whether your project demands IPC Class II or Class III, we have the expertise, certifications, and production capacity to deliver on time and on spec.

✅ Certified Quality

• Full compliance with IPC-A-610 Class II & III
• ISO 9001 and IPC-6012 certified processes
• In-house inspection and testing (AOI, X-ray, electrical testing)

✅ Advanced Manufacturing

• Multi-layer PCBs (up to 30+ layers)
• HDI, blind/buried vias, controlled impedance
• Surface finishes: ENIG, HASL, OSP, Immersion Tin/Silver
• Materials: FR4, High-Tg, Rogers, Polyimide, Aluminum

✅ Engineering Support

• DFM/DFA reviews to optimize your design
• Stack-up and impedance modeling
• Design rule checks for Class II or Class III compliance

✅ Fast Turnaround & Scalability

• Prototype to full-scale production
• Quick-turn services available
• Global logistics and supply chain support

Final Thoughts: Build It Right, Build It Once

Choosing between IPC Class II and Class III isn’t just about meeting a spec — it’s about matching your product’s reliability needs with the right manufacturing approach. Overbuilding can inflate costs; underbuilding can lead to field failures.

That’s why partnering with an experienced PCB manufacturer like DQS Electronic Group is critical. We help you navigate IPC standards, optimize your design, and deliver boards that perform — whether they’re powering a smart thermostat or a satellite in orbit.