If you’ve been in the market for a PCB (printed circuit board), you’ve probably seen various board designs being labeled Class 2 and Class 3 products. But what does that exactly mean? The IPC (Institute for Printed Circuits) is an association that releases standards manufacturers need to meet in order for their PCBs to be certified. Some of those IPC standards, naturally, regard the quality of production. The standards in question are IPC A-610 (Acceptability of Electronic Assemblies) and IPC 6011.
Thanks to these standards, we now have different IPC classes for different PCBs. These classes basically regulate the level of quality of production, with each class being different from others. There are three main classes:
- Class 1: the lowest in quality
- Class 2: the middle ground between Class 1 and 3
- Class 3: only PCBs of the highest quality can call themselves Class 3
There’s also a newly-formed Class 3A, which we will talk about further on. But first, let’s take a look at what makes these classes different.
Class 1 is the lowest-tier IPC class. It usually ends up in general electronic products. These PCBs satisfy only the lowest quality requirements, and their lifespan is generally short. Naturally, they are not as reliable as higher-class PCBs. In fact, when we label a PCB IPC Class 1, there is no guarantee about its key characteristics and reliability.
Class 1 boards in products such as TV remotes, LED lights, children’s toys, and similar. Basically, they end up in devices that don’t have a noteworthy life expectancy and don’t need to perform complex functions. Class 1 PCBs usually come with several cosmetic defects, as these defects don’t obstruct the PCBs’ simple functionality. There is no real necessity for uninterrupted service when it comes to Class 1 boards, and high reliability is not essential.
Choosing Class 1
So, why would someone opt for a Class 1 product? Well, as you might have guessed, they are also the cheapest. Obviously, nothing stops you from putting a Class 3 PCB into your toy or remote control. But, that’s not necessary. If you’re looking to shave off the costs where you can, especially if you’re dealing with high-volume production, Class 1 will do the job for you.
However, it’s worth noting that many PCB manufacturers don’t really offer Class 1 boards (anymore). For example, at MKTPCB, you can only get a Class 2 or Class 3 board. Class 1 quality usually signifies that the production level is relatively low, something we do not engage in.
Compared to Class 1 PCBs, Class 2 boards have a much longer life cycle and better reliability. But, as we’ve said, Class 2 is the middle class here — it’s life cycle and dependability are not as good compared with Class 3.
Basically, you get a Class 2 board when you want uninterrupted service that is not crucial to its functioning (i.e., uninterrupted service is desired, but not critical). As such, Class 2 PCBs can come with some cosmetic anomalies (or imperfections), but they are not as tolerable as with Class 1 boards.
In other words, Class 2 boards offer continued performance and extended life expectancy, but up to a certain point. These boards are the most common ones, and they end up in products such as smartphones, TVs, laptops, tablets, ACs, and so on.
These boards will work for several years, but they can sometimes fail to perform a particular function. However, while this failure may be frustrating, it’s not going to result in a crucial mistake that can affect someone’s well being.
Obviously, they are cheaper than Class 3 boards. However, it’s well worth noting that Class 2 PCBs don’t necessarily have to be too far away from Class 3 PCBs in terms of quality. For instance, they can match a higher-tier board’s quality in many ways, just not all of them. Unlike Class 1 boards, Class 2 boards can work in harsh environments, but not in extreme ones.
Finally, we have Class 3 boards. These are top-tier boards for products that come with the highest customer requirements. Build requirements for Class 3 PCBs offer the least leeway.
We use these boards in critical systems, and they simply must offer continued performance and performance on demand. Uninterrupted service is critical, and there is no tolerance for any downtime of the board. Simply, when called to action, the PCB must deliver, no matter when, and no matter the function. These boards come with the longest life expectancy.
Imagine, for instance, that you’re driving your electric car. With your foot down, you’re doing a 100 on the freeway. Suddenly, the circuit boards that are crucial for your car’s performance start breaking down, and there’s no way for you to react. That’s not a good situation to be in. Even worse, if we look at some medicinal equipment, such as life support, continuous performance is paramount.
That’s why Class 3 boards find their place in automotive products, electronic medical devices, military equipment, etc. These PCBs will work in the most extreme environmental conditions.
Obviously, such a high level of production standard does come with a price. Additionally, it takes more time to make a Class 3 PCB. They have to fulfill all of the IPC criteria to be labeled as Class 3. As a result, the machinery takes more time to assemble. For example, we have to slow down surface mount machines to ensure the placement accuracy is at the required level. Then, additional cleaning processes and inspections take place, which all leads to a higher price and a longer production period.
There’s also another Class we haven’t put on the list above — Class 3A. The reason for that is because 3A is a new class with very limited use. These boards are a step above Class 3 PCBs, and the necessity for such a high-level PCB is rare. Usually, only military and space avionics require Class 3A boards. This class also has its use in missile and airborne systems.
Since they have to perform in Outerspace conditions, and they must not malfunction, it’s obvious they have to satisfy every detail without the tiniest of deviations. However, unless you’re the new Elon Musk or plan to invade someone, you will never need a Class 3A board.
Differences in Production
So, what are the differences in actual production? We’ve mentioned how Class 1 and 2 tolerate some cosmetic deficiencies. But what exactly is it that we check in a PCB? Well, the IPC has released a complete checklist of the requirements. There’s a checklist for five different production levels, from project start level to cleaning and conformal coating.
Without getting too deep into it (the checklist is quite extensive), let’s look at a couple of examples.
Firstly, you have design rules for annular rings. Class 3 annular rings cannot have any fractured annular rings, while Class 2 boards will accept some breakouts. With Class 2, the allowed breakout is a 90-degree one, while Class 1 PCBs can have a 180-degree ring breakout. If you are interested in further annular ring design requirements, we suggest you watch this video from Altium, where they talk about it in more depth.
After that, we have copper voids with through-hole plating. Copper voids are basically the empty space in the barrel of the hole where copper is missing. These voids expose the material of the hole. According to IPC, Class 1 boards can have three such voids in 10% of their holes. Class 2 allows only for a single void in 5% of the board’s holes, while Class 3 (and Class 3A) don’t accept any voids.
These are just two examples that we’ve used to illustrate how detailed and strict the IPC criteria are.
IPC Classes are basically a quality guarantee. They show the level of production quality that has gone into a particular PCB. There are three main classes, with the lowest one being Class 1, and the best one being Class 3.
These classes differ in their life expectancy, as well as performance levels. These classes’ criteria are rigorous and extensive, which makes it challenging to create a high-quality PCB. That’s why it’s essential to work with a manufacturer with years of experience, which is the case with us here at MKTPCB.
While Class 3 boards are the best of the three, you don’t need to use them all the time. If you’re not sure which class would best suit you, you can freely contact us. Aside from giving you advice, we can also offer a free quote for your needs.