The classification of printed circuit boards is determined by the quality and importance that the device has in our daily lives.

A higher quality device is a computer or television. Although failures of these devices can have unfortunate consequences (no one wants your hard drive to stop working and lose all your files). The circuit boards inside these machines are designed for long term use and require the quality to meet this premise. Unlike your kids' electronic toys and other "cheap" consumer goods.

Special PCBs for equipment that must operate without error, we classify PCBs according to IPC Class 3. These electronics operate continuously without error and perform the most important functions in electrical equipment.

Class 3 PCBs are implemented in everything from computers in commercial aircraft, military applications, space shuttles, automobile braking systems, to precision medical equipment.

Class 3 manufacturing quality is undisputed, but not required for all devices. Therefore, IPC grades are also lower, and we will explain the key differences between Class 2 and Class 3 printed circuit boards in this article.

Definition of IPC classes for printed circuit boards

There are three general performance classifications currently used in PCB manufacturing. Each class is a set of standards monitored by the IPC according to the IPC-6011 standard. The levels determine not only the quality of the board, but also their functionality, performance, and frequency of inspection.

Class 1 PCBs – General Electronic Products. Their circuit boards are generally used in simple electronics such as flashlights, toys, remote controls and related products. They are considered to be of the lowest quality and have a short life cycle. Although they are not particularly faulty over time, the devices in which they are contained are built to last for a limited period of time but can be easily replaced or repaired.

Class 2 PCBs – Class 2 electronic assemblies last longer and are of higher quality than their Class 1 counterparts. They include everything from microwaves, smartphones, laptops, televisions, air conditioners, and other household appliances. Class 2 PCBs have great functionality for devices that are designed for continuous operation but are not considered mission critical.

Class 3 PCBs – Electronic products with high reliability. Devices containing these circuit boards must be manufactured with extreme precision and quality and are designed to last a very long time. Examples of electronics containing Class 3 manufacturing are medical devices and equipment used for aerospace and military applications.

The final performance class of the printed circuit board assembly cannot be higher than the performance class of the bare printed circuit board. This means that while a bare Class 2 printed circuit board can be used for Class 1 printed circuit boards, it cannot be used in Class 3 manufacturing.

Ultimately, the type of printed circuit boards used in products is determined by their functionality for the end user. For example, a cheap electronic toy does not meet the same standards as a device that depends on seamless functionality, such as an EKG or a military aircraft. Thus, different manufacturers often specialize in different classes of circuit boards because of the exacting standards required to create Class 3 circuit boards.

What belongs to Class 3?

Class 3 manufacturing standards are the top of the line when it comes to quality and accuracy. An important question to ask yourself before you start choosing a grade: Does my product require it?

As costs and time increase, it's a good idea to consider what costs may be associated with recalling a defective product due to a defect. Going back to the earlier example, a broken computer can lead to frustration for the customer who, in the worst case scenario, will choose a different brand of computer. A faulty medical device or aerospace computer has a much more serious impact and so requires higher quality components.

There are standards and best practices in the aerospace industry, such as AS9100D certification for the development of aerospace component manufacturers and materials, including Class 3 printed circuit boards. Such certifications require numerous audits to ensure accurate quality focused on product safety, preventing counterfeit parts and minimizing human error.

To meet the stringent standards of Class 3 manufacturing, special equipment and processes are required to assemble these circuit boards, which can increase production time and costs.

What class of boards do I need?

Does your product require a Class 3 PCB or will a Class 2 PCB suffice? To understand which classification is right for you, it's best to start by knowing the end functionality of the device. While the increased performance may be appealing to the product, the higher cost incurred for the PCB may not justify the end product.

Advantages of Class 2 printed circuit boards

Design – Having Class 2 circuit boards makes the placement and routing of components much simpler, resulting in reduced costs in all areas.

Manufacturing – Assembling a Class 2 printed circuit board does not require the same amount of time or materials that Class 3 requires. Class 2 manufacturing requirements are normatively lower than Class 3.

Inspection – Since Class 2 PCBs are not typically used in harsh environments or in facilities requiring a high degree of functionality, inspection times are significantly reduced.

Advantages of Class 3 PCBs

Design – Class 3 PCBs must meet much more stringent standards in terms of specifications and tolerances. As a result, the additional cost results in much higher quality over a longer period of time. With more time spent designing these boards, users can expect trouble-free results for a long time.

Manufacturing – The process of manufacturing Class 3 printed circuit boards is much slower. The process looks a little different than you might expect with Class 2 boards – installation and cleanliness are a much higher priority.

Inspection – Strict inspection is required for every Class 3 circuit board. Repeated inspection of Class 3 PCBs helps identify errors early in the manufacturing process at the expense of production time and final cost.