In electronics manufacturing, printed circuit boards are separated into three categories: 1, 2, and 3. The printed circuit board classification system, developed and monitored by IPC, has categories that reflect the level of quality of each circuit board type. Based on the IPC-6011 standard, the categories range from lowest (Class 1 standards) to highest (Class 3 standards).
The major difference between each class is the degree of inspection electronics assemblies must undergo and the quality standards to which they're subjected. Understanding the classes and their requirements can be helpful to OEMs who aren’t sure to which class their product should belong. Customer requirements and cost can weigh heavily in deciding which class to pursue.
Let’s take a look at the IPC class definitions and when you should consider each of them a possibility for your product:
| IPC Class 1 | IPC Class 2 | IPC Class 3 | |
| Category | General electronics | Dedicated service electronics | High-reliability electronics |
| Life cycle | Short | Long | Very long |
| Quality | Cheap | Good | Failproof |
| Examples | Toys, flashlights, smartphones | Laptops, Microwaves, and some mining equipment | Aerospace, military, & medical applications |
The first electronic products class is referred to as the “general electronics” category. This consists of boards with the lowest quality requirements and is mostly found in products with an expected short life cycle.
Think of a superhero toy you’d buy your nephew at Target. It lights up and echoes the hero’s signature catchphrase with the push of a button. The toy works great for your nephew for weeks after you give it to him, but would you be surprised if the light or one of the buttons stops working after a year or two? Probably not.
This is basically the “get what you pay for” class. These electronics are held to the lowest standard of quality and thus are usually found in cheap, high-volume productions.
Some electronics manufacturers don’t even bother with the class one category. Matric and Dynamic, for example, do not make electronics in class one. All boards manufactured through our facilities are either Class 2 or Class 3, both due to the nature of the markets we serve and our dedication to product quality.
Class 2 electronic devices encompass all electronics where continued performance and an extended life cycle is required -- to a point. Uninterrupted service is desired, but not critical. Along with what's in the chart above, IPC Class 2 examples include:
In other words, these are items where an early life cycle failure would have you red-faced and slamming your fist, but wouldn’t put your life at risk.
Something to keep in mind: You’ll want to know which class you want to pursue prior to board design, as products must be specially designed for Class 2 and Class 3 specifications. A board designed for IPC Class 2 specifications can potentially achieve many of the same build requirements for Class 3, but rarely all of them.
Have questions about our design, assembly, or testing capabilities? Check out our free downloadable guide below:
The third class of circuit boards are subject to strict guidelines due to their importance in the field.
While Class 1 electronics are usually cheap and easily replaceable items and Class 2 electronics are more important and require a longer life cycle, Class 3 electronics are mission-critical items. Whether it’s a pacemaker or a military radar, a product that needs to meet IPC Class 3 requirements must use high-reliability electronic components to ensure uninterrupted service.
These electronics are usually the highest of quality, and many OEM products that could pass as Class 2 opt for the IPC Class 3 standard because the benefits of higher-quality electronics outweigh the cost of additional testing and inspection.
Remember, the IPC PCB classes reflect the level of quality of each printed circuit board type, so in some cases, it's crucial to make sure your manufacturer is qualified to work with you.
Some electronic contract manufacturers only handle Class 1 electronics, so make sure you ask upfront. A contract manufacturer that specializes in Class 2 and/or Class 3 electronics may also be able to talk you through factors like customer requirements and cost.
No matter what the case is, make sure you and your PCB manufacturer are up-to-date on all electronics compliance standards, from RoHS to IPC standards compliance. Check out our free guide to electronics manufacturing standards!
Q&A:
The specific testing and inspection procedures required for IPC Class 1, 2, and 3 electronics vary. Below we outline some of the key procedures:
|
Class 1 |
Class 2 |
Class 3 |
|
|
Visual Inspection |
A basic inspection is completed to make sure the assembly is free of obvious defects and/or significant contamination. |
The inspection is more detailed and looks for minor defects such as alignment or residue. |
The visual inspection is highly detailed and looks for anything that could impact performance and reliability. |
|
Measurement and Testing |
Measurements for hole size, conductor spacing, and plating thickness are basic, ensuring components fit and function. |
More stringent measurements, with tighter tolerances for components and connections. |
The most stringent measurements are used to ensure the highest reliability and precision for critical applications. This includes extensive use of tools like microscopes and calipers. |
|
Solder Joint Inspection |
Solder joints are inspected for basic acceptability, such as proper wetting and the absence of gross defects. |
Inspections include checks for minor imperfections and require higher-quality solder joints with better fillet formation and alignment. |
Requires flawless solder joints, with rigorous criteria for fillet height, wetting, and joint strength. Any minor imperfection can be cause for rejection. |
|
Cleanliness and Surface Finish |
Basic cleanliness to prevent major contamination issues. |
Higher standards for cleanliness and surface finish to prevent medium-term reliability issues. |
Strictest standards to ensure no contaminants affect the high reliability and long-term performance of the assemblies. |
|
Documentation and Reporting |
All classes require documentation of inspection results, but the detail and thoroughness increase from Class 1 to Class 3. For Class 3, detailed reports include photographic documentation of defects and recommendations for corrective actions. |
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Training and Certification |
Inspectors for all classes undergo training, but the level of certification and expertise required increases with the class. Class 3 inspections often require the highest level of certification and experience. |
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*For more detailed information on the specific requirements, you can refer to IPC-A-600 and IPC-J-STD-001 standards available on the IPC website.
Potential risks for using a lower-class PCB in a higher-class application include:
(Editor's note: This article was originally published in August 2018 and was updated in June 2024 to reflect the most up-to-date information.)