According to the IPC standards, PCBs fabricated in class 3 are specifically designed for demanding applications. These boards are useful when the operational environment of the board is not harsh. Also, it could be useful in applications that require critical performance. Therefore, all these cases require the need for rigid PCBs fabricated according to IPC standards.
There are standards in the PCB industry that manufacturers must adhere to. The IPC class 2 and Class 3 are two important standards in the PCB industry. In this article, we will focus majorly on the IPC 6012 Class 3 standards.
The IPC Standards
IPC stands for Institute for interconnecting and Packaging Electronic Circuits. Also, it was initially referred to as Institute for Printed Circuits (IPC). There are different IPC classifications in the PCB industry. This institute has generated a lot of standards for PCB design and performance.
These standards define PCBs according to the required level of device reliability. Every class has its qualification requirements and guidelines performance for fabrication, inspection, and testing of PCBs. Also, the standards for each class addresses issues like trace sizes, component placement, and others. Furthermore, it is important to know the IPC class definitions.
The Class 1 classification is for general electric boards with a short life. An example is the ones found in typical everyday products like a Tv remote control. Class 2 PCBs are for dedicated service electronic products. These circuit boards have an extended life. Also, they are available in an air conditioner or a television. Class 3 PCBs have greater tolerances than Class 1 and Class 2 PCBs. All these classifications help to understand the IPC standards.
What is a Class 3 PCB?
Class 3 PCBs are ideal for high-performance and critical applications. These boards are very reliable. They help to achieve great performance in medical or military applications. Also, Class 3 PCBs offer a performance on demand. The operational environment of this PCB can be very harsh. Also, these boards require a high level of testing and inspection based on stringent standards.
This category comprises critical systems like military equipment, automotive PCB, etc. The class 3 PCB fabrication standards offer precision and quality. However, not all products require the use of class 3 PCBs. Class 3 boards meet more stringent standards as regards tolerances and specifications. Therefore, there is much high quality due to the additional expense.
Class 3 PCBs are widely used in high medical and aerospace applications. The devices used in medical applications need to keep people alive. Planes in the air and military equipment function in extreme environments. These devices are extremely critical. Therefore, these boards are specifically designed with high precision and quality control. Users can expect great outcomes over a long period of time.
Also, the manufacturing process of this PCB is slower. This is because manufacturers pay more attention to produce functional and flawless boards at the expense of time. Also, manufacturers prioritize cleanliness and installation in class 3 PCBs. These PCBs produce high reliability electronic products.
PCB manufacturers ensure they carry out rigorous testing and inspection for every IPC class 3 PCB. Also, inspection of Class 3 PCB helps to detect defects early in the manufacturing process. Class 3 fabrication process ensures the greatest degree of quality and functionality.
What is IPC-6012 Class 3?
The IPC-6012 is a standard generated for the quality and performance of rigid PCBs. This specification creates the qualification and performance requirements for the rigid PCB fabrication. These specifications are applicable to metal core PCBs, multilayer, single side, and active/passive embedded PCBs.
The IPC-6012 is a specification that defines default specifications and requirements for class 3 PCBs. This standard offers the actual acceptance requirements for a rigid printed circuit board. IPC-6012 defines the qualification and classification requirements for rigid boards. It defines requirements for Class 3/A military and space avionics. Also, it defines requirements for the three classes of PCBs.
What is the major difference between IPC-6012 and IPC-A-600?
The IPC-A-600 establishes the acceptance criteria for every class specification. Also, it describes the ideal conditions for printed circuit boards. It is the visual representation of least requirements established in different PCB specifications.
The visual representations of IPC-A-600 reveal certain criteria of the performance requirements of the IPC-6010 series. In addition, manufacturers and customers can agree on the criteria to replace some requirements.
The IPC-6012 is a performance requirement and specification document. This document defines default requirements for each PCBs’ class. Also, the IPC-6012 offers the actual acceptance criteria. This document sets the requirements needed for all three classes of PCBs. However, both IPC-A-600 and IPC-6012 are applicable for rigid PCBs.
IPC 6012 Class 3 Annular Ring
The annular ring is sometimes a defect in IPC product classes. There are several possible production characteristics that are defects in some boards. Annular rings are one of the structural characteristics that could be a defect.
Sometimes designers confuse pad sizes and annular ring, although they are related. PCB designers need to place a pad size large enough on the surface layer. This helps to ensure the leftover annular ring during fabrication is big enough.
It is important to ensure that the leftover annular ring in every IPC class is large enough. Therefore, choosing the appropriate land size for a via helps to size the annular ring. In as much as your vias are big enough, you have accommodated fabrication tolerances in your circuit.
In order to consider the IPC class 3 products as successfully fabricated, there must be some leftover annular ring. There are two ways for measuring annular ring for internal and external layers. For internal layers, you measure the annular ring from the edge of the hole to the pad’s edge. As regards external layers, you measure the annular ring from the via wall plating’s sedge to the pad’s edge.
Some Defect Criteria in IPC PCBs
The IPC standards define the defects acceptable for class 1, 2, and 3 PCBs. These defects include the ones that may affect performance. Also, this includes those that have no impact on reliability and performance.
Solder joints
Solder coverage for joints is an example of defect specified by IPC. With THT components, this mean how much solder wets the lead in the via. For class 1 PCB, there is no specification. However, Class 2 specifies 1800 and class 3 specifies 2700.
Annular rings
IPC defines the ring’s width around the hole and how centered the hole should be. Class 1 ring enables breakout of 1800 while Class 2 allows breakout of 900. The specification for Class 3 is different. Here, the ring should be at least 0.050mm around the hole.
Component misalignment
SMT components may overhang their solder pad. There are guidelines for such component overhang. For class 1, there should be less than 50% of pad width. Also, the pad width for Class 2 should be less than 50%. For Class 3, the pad width should be less than 25%.
How to Design an IPC PCB
IPC PCB manufacturing requires a special process. There are required ways to manufacture these PCBs since they are special. These printed circuit boards are reliable and safe to use. Also, the IPC standard ensures that manufacturers fabricate high-quality and safe boards.
In addition, the IPC guidelines ensure that fabricators maintain good functionality and performance of their products. Also, these standards ensure PCB manufacturers maintain consistency and cost reduction. How, do you design an IPC printed circuit board? Here are tips to design this board.
- Ensure the spacing specifications are within the recommended tolerances
- Ensure the whole drill holes meet the requirements for quality and size. Also, ensure the holes align with the aspect ratios of the equipment of your manufacturer.
- Be certain that the specifications of the solder mask falls within the recommended tolerances. Class A PCBs’ solder mask specifications must match its class tolerances. Also, the same goes for products in other classes.
- Make sure your manufacturer integrates high-quality control. This includes exercises like AOI inspections in the manufacturing and assembly process.
- Ensure cleanliness is your contract manufacturer’s priority. After all, you don’t want PCBs that are fill of debris. Unclean boards can affect the functionality of a device.
- Make sure you use all the specifications of class 3 for the entire PCB properties.
- It is important to adhere to IPC standard if you want a functional board. Also, it will be very helpful if you have a manufacturer that can work according to the regulatory requirements.
What are the Precautions for IPC Products?
IPC products are different from other PCB products. These products have their own standards. Therefore, it is important to observe some precautions when dealing with IPC printed circuit board. Below are four factors to consider as regards IPC products
Cost issues
Printed circuit board manufacturing costs a lot. This is one of the biggest challenges for manufacturers. Also, there are some factors that contribute to the high cost of circuit boards. For instance, the surface treatment and material type impact the cost of PCB.
IPC PCBs are specially designed to meet certain standards. Therefore, this means there will be high cost. As a PCB manufacturer, you may need to maintain a balance between quality and price. Also, cost is a major issue when it comes to IPC PCBs. Therefore, IPC PCB manufacturers must maintain a perfect balance between quality and price.
Mounting technology
Through hole technology can sometimes be the best choice. IPC have some standards for THT PCB layout. THT is ideal in cases like industrial and space applications. SMT is a great mounting technology option. The IPC-DRM-18 specifies the identification and placement of components. Also, it is important to ensure the placements of components are in the right procedures.
Conclusion
IPC creates the standards for manufacturing, designing, and testing PCBs. Boards that adhere to these standards are widely used in electronics manufacturing. Also, you will find IPC Class 3 in advanced electronic products like life support systems and military airborne systems. Advanced communication equipment also features IPC PCBs.
