PCB Acceptance Standards Overview
IPC / GJB / GB — Three-System Comparison Handbook

Hardware Engineer Reference Handbook · September 2026

I. IPC International Standards System

IPC (Association Connecting Electronics Industries) standards are the most widely recognized PCB acceptance standards in global electronics manufacturing, particularly dominant in North America and the Asia-Pacific region. The core standards fall into two categories: Workmanship Acceptance Standards (IPC-A-600) and Performance Specifications (IPC-6010 series).

IPC Three Classes Explained

IPC classifies PCBs into three classes based on end-use application and reliability requirements. The higher the class, the lower the defect tolerance:

Class	Application	Reliability Requirement	Defect Tolerance
Class 1	Consumer electronics Toys / appliances	Functional only, low lifespan requirement	Minor cosmetic defects allowed
Class 2	Industrial control Telecom / automotive	Sustained performance + long life, intermittent downtime for maintenance allowed	Low tolerance without affecting function
Class 3	Military / aerospace Medical / automotive Critical components	High reliability + continuous operation, no interruption in extreme environments	Zero tolerance Mandatory full inspection

Note: IPC-6012DS 3A Class (sometimes called "Class 4") is a higher level, suitable for space and military avionics, with near-perfect manufacturing standards and extremely high costs.

II. GJB National Military Standard System

GJB (National Military Standards of the People's Republic of China) is the mandatory technical standard system established by China's defense science and technology industry for military products. In the PCB field, GJB standards apply to high-reliability applications such as military and aerospace, and the technical content closely corresponds to U.S. military standards MIL-PRF-31032 / MIL-PRF-55110.

GJB Classification and IPC Correspondence

GJB 362B also classifies products into three grades based on application and reliability requirements, with approximate correspondence to the IPC Class system:

GJB Grade	IPC Equivalent	Application Scenario	Lifespan Requirement
Grade Ⅰ	≈ Class 1	General purpose, consumer electronics	5-10 years
Grade Ⅱ	≈ Class 2	Dedicated service, telecom / industrial control / commercial equipment	10+ years
Grade Ⅲ	≈ Class 3	High reliability, military / aerospace / life support	15+ years

⚠ Note: GJB Grade Ⅲ requirements are overall higher than IPC Class 3, particularly stricter in environmental adaptability and traceability. The two roughly correspond but are not equivalent.

III. GB/T National Standards System

GB/T standards are recommended national standards issued by the Standardization Administration of China. In the PCB field, GB/T standards are partially equivalent to or reference IEC (International Electrotechnical Commission) or IPC standards, serving as the foundational basis for domestic civilian PCB manufacturing and acceptance.

GB/T standards do not adopt Class 1/2/3 classification, but instead have separate specifications by product type (single-sided/double-sided / multilayer / flexible). Acceptance requirements are generally at the IPC Class 1~2 level, with some indicators referencing IEC standards. For high-end applications, domestic manufacturers typically adopt IPC or GJB standards directly for acceptance.

IV. IPC vs GJB vs GB/T — Three-System Overall Comparison

Dimension	IPC (International)	GJB (Military Std)	GB/T (National Std)
Standard Nature	Voluntary industry Globally applicable	Mandatory Military-specific	Recommended Domestically applicable
Classification	Class 1/2/3	Grade Ⅰ/Ⅱ/Ⅲ	By board type No classification
Environmental Adaptability	Standard environment	Extreme temp / vibration / humidity / salt spray	Standard ~ industrial
Lifespan Requirement	5-10 years (Class 3 longer)	15+ years	5-10 years
Defect Tolerance	Graded tolerance Class 3: zero tolerance	Near zero defect	Minor defects allowed
Documentation Traceability	Basic requirements	Full-process traceable	Basic requirements
Quality System	ISO 9001	GJB 9001 (Military version)	ISO 9001
Tg Value Requirement	Per material spec	≥170℃	Per material spec
Barrel Copper (Highest Grade)	≥25μm (Class 3)	≥25μm (Grade Ⅲ)	≥18μm (Multilayer)
Acceptance Method	Sampling / full inspection (by class)	First article qualification + lot acceptance	Sampling inspection
Special Tests	Thermal stress / solderability Insulation resistance	Salt spray / electromigration / vibration shock / thermal shock	Warpage / solderability Withstanding voltage
Cross-Reference	International standard	≈MIL-PRF-31032	Partially references IEC/IPC

V. Quick Reference: Which Standard Should My Board Be Accepted Against?

Common Rejection Defects Quick Reference (Based on IPC Class 2)

Defect Type	Acceptable (Class 2)	Rejection Criteria
Pad / Hole Misalignment	Annular ring ≥50μm	Annular ring breakout / no connection
Missing Solder Mask Dam	Dam width ≥50μm	No isolation between pads
Copper Foil Scratch	No substrate exposed Depth < 30% copper thickness	Substrate visible / affects electrical
Measling / Micro-Cracking	≤50μm Not crossing conductors	Crosses multiple traces / >50μm
Void in Hole	≤5% barrel area Not through-wall	Affects continuity / strength