In the PCB industry, there are standards guiding the design, manufacturing, as well as assembly of circuit boards. Creating standards is a good way of ensuring the functionality and safety of circuit boards. Therefore, manufacturers must adhere to these standards. There are several standards in the PCB industry and each standard is created for a particular purpose.
One of the most popular standards in the PCB industry is the IPC standard. The Institute of Printed Circuits (IPC) was created to help PCB manufacturers develop better and functional electronics. IPC standards focus on all aspects of PCB production and as such these standards are of different types. The IPC 6011 is a popular standard manufacturers adhere to. Our main discussion here focuses on the IPC 6011 and what aspects of PCB manufacturing it covers.
What is IPC 6011 Standard?
The IPC 6011 standard is a guideline that provides the requirements for the production of circuit boards and as well outlines the functionality and quality they meet. These standards cover all aspects of PCB production from design to assembly and testing, inspection, and even documentation.
The IPC 6011 standard describes three main class definitions, which indicate quality level from the lowest to the highest. It should be noted that the degree of inspection is the difference in these classifications.
The major classifications are:
IPC 6011 Class 1 Electronics: This classification describes the manufacturing standard of general electronics products like toys. Also, computer and computer parts. These products don’t have much effect on our daily lives. They are ideal in applications where there is no much importance attached to cosmetic imperfections.
IPC 6011 Class 2 Electronics: The class 2 electronics classification covers Dedicated Service Electronics Products like televisions or other home appliances. In some ways, these electronic products have less impact on our lives. IPC 6011 Class 2 electronics are more critical than Class 1. Robust computers and communication equipment are a good example of class 2 devices.
IPC 6011 Class 3 Electronics: This is the third classification which describes the High-Reliability Electronics Products like aerospace and medical devices. These devices have a major impact on our lives. For instance, medical devices are used for life saving purposes. If these devices fail, human lives and a lot will be at stake.
Human lives could be at risk when parts or components of aerospace devices fail. Therefore, there is no room for error in devices like this. In products like this, there is no tolerance for downtime. Flight control systems or life support machines must function as required.
What do these Class Definitions Really Mean?
The three classifications of devices based on the IPC standards points out the severity of defects that can be allowed in a circuit board. While some defects can be tolerated in class 1 electronics Class 3 can’t tolerate some manufacturing defects. If a circuit board has many defects or extreme issues, such a board won’t be categorized as a class 3 board. The defects will disqualify the ranking of the board as Class 3.
A good number of manufacturers produce their circuit boards to meet up with the IPC standards. Sometimes, it all depends on checking a board for defects and grouping it in the right class. Although most PCB manufacturers try to produce quality and reliable boards, you need to specify the class of PCB you want. This is because some PCB manufacturers don’t have the necessary equipment that meets the standards of class 3 PCBs. In some cases, the performance of a board might meet the criteria for a class 2 board.
If such happens, your board will yield more and this will help you save more when you opt for a Class 2 board. However, if the application for which a board will be used is mission-critical, then a class 3 board is an appropriate choice. Ensure you have a proper discussion with your contract manufacturer about the type of PCB class your electronics project requires.
Defects Criteria Specified by IPC 6011
There are many defects found in a circuit board. The IPC standards have a list of defects they have specifications for. Some of these defects can affect performance while some are cosmetic and will definitely have no effect on reliability or performance.
Annular rings
The IPC 6011 standard specifies the center of the hole and the ring’s width around the hole. A Class 1 ring can have 189 degrees breakout while Class 2 allows for 90 degrees breakout. For Class 3 rings, the IPC specifies its minimum measurement at 0.050 mm around the hole. The specifications for each class differs.
Solder Joints
The solder coverage for joints is specified by the IPC 6011 standard. This indicates how well you should use solder to wet the lead in the via . There is no specification for Class 1 since it is a general electronics product. On the other hand, Class 3 and Class 2 require 270 degrees and 180 degrees respectively.
Component misalignment
This is another defect specified by the IPC. A good number of SMT components experience tombstone or overhanging of the solder pad. The IPC made some guidelines for component overhang. For Class 1 and Class 2 PCBs, there should be less than 50% of pad width while that of Class 3 should be below 25% pad width.
According to the IPC 6011 PDF, other defects specified include non-wetting, electromagnetic issues, acid traps, and interoperability.
In some scenarios, no specifications are detailed for Class 1, but there are different guidelines for defects for both Class 2 and Class 3. Sometimes, the three classes have similar requirements for a particular defect.
You should note that the IPC PCB classification could be very complex and electronic manufacturers need to choose the appropriate class for their board. However, manufacturers need a proper understanding of the requirements of each standard so as to know what to go for. Also, they must be aware of the associated manufacturing considerations of these boards.
Conclusion
IPC 6011 standard helps manufacturers to adhere to certain guidelines concerning the production of printed circuit boards.
