A detailed guide on flexible PCB

Flexible PCB – An Overview 

Printed circuit boards or PCBs are the fundamental elements that are liable for advanced smart technology. Each of the electronic elements or gadgets that you use consists of printed circuit boards. Flexible PCB is another advanced innovation of the latest technology that makes a device better in several aspects. A flexible PCB is different from a conventional PCB, and the features are different as well. As the name suggests, a flexible PCB can be flexed as per requirements. You can’t change the structure of a general PCB to fit that into a particular machine. The scenario is quite different when it comes to a flexible PCB. A flexible PCB is bendable, and you can transform the shape of a flexible PCB for multiple interconnecting panels. This particular feature of flexible PCBs allows those to fit into devices of any size. A flexible PCB is way more efficient than a conventional PCB in terms of connectivity and fast functions. In this article, we will unfold different facts that are related to flexible PCBs. 

What are flexible printed circuit boards? 

From the structural aspects, a flexible circuit board is not much different from a regular circuit board. But you can bend or reform a flexible PCB when you’re installing it inside a device. A flexible PCB allows you to bend it without damaging the whole circuit, and that’s the key feature of this kind of circuit. The fabrication of a flexible printed circuit is not similar to a regular PCB. These PCBs are mainly used in devices that are small and short.

Types of flexible PCBs

Based on the structures and functions, flexible PCBs can be categorized into four major categories. Here we are going to discuss the main four types of flexible PCBs.

• Single-sided flexible PCB- This is the simplest form of flexible PCB. Every flexible PCB includes a dielectric layer, and a single-sided flexible PCB is no exception. Generally, such a PCB has a single layer of metal traces on a particular dielectric layer side. In the case of a dielectric PCB, the layer of metal traces can be attached to any of the sides, and the other side won’t contain a layer.
• Double-sided flexible PCB- In the case of a double-sided flexible PCB, the PCB includes two layers of metal traces on both sides of the dielectric layer. You will also find holes in a double-sided flexible PCB that ensure uninterrupted connection all over the circuit. Like a single-sided flexible PCB, a double-sided one also includes a single dielectric layer.
• Multi-layer flexible PCB- This kind of PCB includes multiple dielectric layers placed into different portions of the PCB. Besides that, such a PCB includes numerous layers of metal traces separated by those dielectric layers. Naturally, a multi-layer flexible PCB’s design and structure are way more complicated than other flexible PCBs.
• Rigid-flex circuits- A rigid-flex circuit includes more than one circuit layer, and an epoxy bonding film connects the circuit layers. A rigid-flex circuit can be considered as a perfect combination of rigid and flex circuit boards. 

Materials used in flex circuits 

There is no doubt that the materials of a flexible printed circuit board are essential in terms of making the circuit function properly. Before designing a flexible circuit board, you are supposed to know about all the materials.

Conductors 

Current flows freely through the flexible circuit due to the presence of conductors. The conductor of a flexible circuit is undoubtedly an essential part of the whole circuit. It will be best if you use copper as the primary material for the conductor. Apart from that, you can also use other components like- aluminum, carbon, and silver. These components are also more or less effective as the primary materials of conductors.

Adhesives 

When it comes to adhesives, you are likely to use adhesives as per the thickness of the circuit’s conductor. Sometimes, engineers also apply adhesives according to the demands of the clients. The primary purpose of using adhesives in a flex circuit is to bind the surface mount component. Epoxy and acrylics are the materials that are often used as adhesives.

Insulators 

These can also be used as conductors, but these don’t conduct current generally. The reason for using insulators in flexible PCBs is to provide additional support to the prominent conductors. The list of materials used as insulators is long, including polyimide, polyester, solder mask, etc.

Finishes 

Finishes are mainly used as protective measures in flexible PCBs, and these protect the surfaces of PCBs from oxidation. Therefore, finishes can be regarded as the primary materials of flexible PCBs. Silver, carbon, tin, nickel- are some of the materials that are mainly applied as finishes.

Benefits of flexible PCBs 

The list of benefits of flexibles PCBs is pretty long, and these are efficient circuits that are vastly used in different kinds of devices. Let’s have a quick look at the main benefits of flexible PCBs.

• Every flexible PCB comes with a compact, and the accuracy of its design is better than a conventional PCB. You won’t have to spend a lot of time assembling a flexible PCB, and the entire assembling process is automated. Therefore, the chances of mistakes or errors during production get lessened.
• No matter the configuration of a device, a flexible PCB is efficient enough to support that. You can’t get that feature in a conventional PCB, and that’s what makes a flexible PCB a better option.
• As you use a flexible PCB in a device, weight management doesn’t remain a point of concern for you anymore. Flexible PCBs are lighter than other PCBs. In addition to that, these PCBs occupy smaller spaces due to the flexible nature.
• There is no electronic device that doesn’t produce a minimum amount of vibration. A flexible PCB is good enough for reducing the vibrational impact of the device. Besides that, such a PCB is capable of absorbing the vibration up to some extent as well.
• Flexible PCBs are the friendliest circuits for use in extreme weather conditions. Each flexible PCB comes with a dedicated cooling feature that helps the device function better.

Applications of flexible circuit boards 

Static application 

In this application procedure, the circuit is bent on requirements to fit into the dedicated slot for a single time.

Dynamic application 

This procedure is slightly different as the circuit is bent multiple times before getting placed into a dedicated slot.

How are flex circuits changing the world? 

Flexible circuits are handy for being used in small, portable devices. Manufacturing small smart devices like smartwatches and other accessories is being comfortable and easy due to flexible circuits. As technology is advancing, more accessories and gadgets are being invented that are small and portable. Previously, people used to think that machines are bound to be big and space-consuming. The invention of flexible circuits changed that idea completely. These circuits are promoting the concept of smart technology rapidly. It can be assumed that the growth of technology will get induced with flexible circuits shortly.