Rigid PCB – everything you need to know
With the development of science and technology, in order to meet various needs, various types of PCBs have emerged, including rigid PCB, flex PCB, rigid-flex PCB. Each PCB has its own advantages and disadvantages. In this post, we mainly introduce the rigid PCB, including its definition, composition, manufacturing process, advantages and disadvantages, applications, etc.
What is a rigid PCB?
Rigid PCB which is inflexible and its structure is solid is a type of PCBs. This means that it cannot be bent or folded because it comes with FR4 stiffener which is very great for added stiffness and rigidity.
Rigid PCBs can provide good support as well as thermal resistance for components. Rigid PCB, contains glass, which gives the circuit board strength and flexibility.
Composition of rigid PCB
There are various layers for Rigid PCB which are connected together by the heat to provide the circuit board a soli-shape. These layers include:
- Substrate layer
This is the first layers and it is also called base material, and it is made of fiber glass. The FR4 is mainly used as a substrate material. It is the most common fiber glass that offers rigidity and stiffness to the boards. The two base materials are used in substrate layer known as phenilcs and epoxies but however, if we talk about the quality, they do not provide us as good as FR4.
FR4 are quite affordable and doesn’t feature any bad smell, when decomposition temperature of phenolics is too low.
- Copper layer
A copper foil is placed at the substrate layer which is laminated on the circuit board by using the heat. Generally speaking, both sides of the board are laminated with copper. However, some inexpensive electronics have only one layer of copper material on the board. Different boards have different thickness.
- Solder mask layer
The layers are placed on above each other just like on the top of the copper layer; solder mask layer is placed. Solder mask layer adds insulation to the copper layer for dodging the future damage.
- Silkscreen layer
The loop goes on the silkscreen layer is placed on solder mask layer. This layer provides the knowledge to the people for making them understand the process of the board. Mostly white is used as it is more visible but it doesn’t mean that other colors are not used. The other colors include: red, grey, yellow and black.
What is the manufacturing process of the rigid PCB?
The rigid PCB manufacturing process includes the following steps:
- Pre-treatment of the substrate to improve its mechanical properties
- Etching to create copper patterns on the surface
- Printing of conductive ink on top of the etched copper patterns
- Drying and curing of the ink layer
Rigid PCB vs. flexible PCB
Both are very good for using in the board but as not a single thing has every feature in it so there is also a difference between these both. The difference indicates that rigid PCBs are not much flexible, while flex PCBs are flexible. If you design a flexible PCB correctly then, it can also be flexed millions of cycles in line without causing any error. However, it cannot be achieved by a rigid PCB.
The increased versatility of flexible PCBs comes at a higher cost, but they are essential for applications with limited space requirements, such as medical devices, space, consumer electronics and automotive applications. Rigid PCBs are very popular due to their low cost. In conventional electronics, and particularly in consumer electronics, with greater space availability, manufacturers can save much by using rigid PCBs.
What is a rigid PCB used for?
Rigid PCB is used in the applications in which high mechanical rigity is required. Furthermore, it provides reduced height and width of the board with the reduced weight. This is also the reason why a lot of electronic enterprises use rigid PCBs in electronic devices. It is typically used in our daily electronic devices, industrial, medical applications, etc.
Benefits of rigid PCB
Cheaper cost: In general rigid PCBs cost less than flexible PCBs. The rigid PCB is a ideal choice when cost efficiency is important. The cost to manufacture only flexible PCBs is too expensive for the majority of production cases, while rigid PCBs can save more spendings for manufacturers.
Compact size: The first benefit of rigid PCB is that it is small in size. The compact size of the PCB ensures that various complex circuitry can be created around it for an application. It takes up less space in an application equipment. Also, as electronic devices become smaller and smaller in size, there is a requirement for the proper connection of components of tiny sizes. The PCB provides a base for this to be done.
Low electronic noise: The rigid PCB is specifically designed to minimize the amount of electronic noise in an application. The current flow of the electronic noise is reduced because the electronic components are merged together in a perfect way. This leads to low radiation emission. Low electric and radiation currents also mean that there is less chances of the PCB picking electromagnetic waves, which lead to a minimization of cross talking between components.
Immunity to movement: The components used in a PCB are not movable because they are fixed by solder flux. This process is performed in such a manner that the components do not move, even when the PCB is exposed to the harsh application environments. This advantage makes the rigid PCB an ideal product in devices that will move and shake when they are being used.
Ease in diagnostics and repair: The design of the rigid PCBs allow a easy repair and maintenance. All of the PCB components are clearly marked, which makes the processes of assembly and disassembly easy. The signal paths of a PCB are well organized and are exposed quite well. This allows the repair technician to easily trace them during maintenance cycles.
In summary, the advantages of rigid PCBs in business applications are incredible. It is a much more effective and efficient way to use them than other materials such as wire mesh or aluminum because it is both stronger and more durable. Rigid PCBs can also be easily integrated into a variety of different materials without compromising their structural integrity.
Limitations of rigid PCB
A rigid PCB with no flexing is not a good choice for all applications. Flexibility is sometimes needed in order to use the PCBs in different applications and environments, which is exactly one of the limitations of rigid PCBs.
The limitations of rigid PCBs are related to the materials used and how much flexing they can handle. There are some other limitations as well, such as how well the board can be soldered and how it handles bending.
What are the applications of the rigid PCB?
Rigid PCBs are used in a variety of our daily products that we rely on for our work, study and communication, for example:
- Computers, laptops, tablets and mobile phones
- GPS equipment
Also, they’re used in important medical equipment in which they are mainly used in large, non-portable apparatus such as:
- CAT scans
- Heart monitors
- MRI systems
Additionally, rigid PCBs can withstand high temperatures because of their copper and aluminium substrates. That is to mean: rigid PCBs are also the perfect circuit boards for the aerospace industry, where they’re used in all kinds of essential equipment:
- Temperature sensors
- Control tower instrumentation
- Aeroplane cockpit instrumentation