Flexible PCB vs. Rigid PCB
2019-11-10PCB Manufacturer: Flexible PCB vs. Rigid PCB
PCB manufacturers around the globe are making the shift from the conventional, rigid Printed circuit boards to flexible Printed Circuit boards mainly because of their outstanding capabilities. Of course, every type of PCB has its own merits and demerits; however, it seems that Flexible PCB has an edge over the conventional ones.
There is no denying the fact that Printed Circuit Boards hold great importance in modern electronics. Therefore, you need to have a complete understanding of their types in order to make the right decision. In the course of this article, we will be discussing different types and their applications.
Table of Content
- Introduction
- What is Flexible PCB?
- Different situation requires different types of Printed Circuit Boards
- Differences and Similarities between Flexible and Rigid PCB
- Application of Flexible and Rigid Printed Circuit Board
- Conclusion
Introduction
Usually, when you come across the word printed Circuit Board or PCB, the first thing that comes into the mind is the conventional PCB. However, the term PCB does not always refer to a rigid Printed Circuit board, on the contrary, it also means Flexible PCB.
In the PCB industry, people commonly use the word Flex circuits for Flexible PCB, but there are several other names as well such as the Flexible Printed Circuit Board, Flexible Circuit Board, Flex Board, and Flexible Electronics.
In recent years and due to the advancement of technology Flexible PCB has gained huge popularity. The reason behind their popularity is their ability to be twisted, bent, shaped or folded into endless configurations.
However, in the end, both Flexible and Rigid Printed Circuit boards offer the same function i.e. connection various mechanical and physical components together.
What is Flexible PCB?
In general, people believe that the difference between a flexible printed board and a conventional one is that flex PCB has the ability to bend. However, there is a significant difference between the two.
Therefore, PCB manufacturers cannot use the same rules for designing a flex PCB and the standard PCB. The manufacturer needs to meet the unique set of rules set by the industry. They have perfected these rules over several years.
A Flexible PCB consists of a dielectric layer, usually of polyimide bonded with a metallic layer of traces. Dielectric thickness ranges between .0005” to .010”, likewise, the thickness of the metal layer is usually <.0001” to >.010”. There are different ways of bond metal to a substrate, you can use an adhesive or you can use different techniques such as vapor disposition.
To ensure that copper does not oxidize, thus it is important to cover the exposed surfaces with a protective layer. There are two common materials used for this purpose, including gold or solder. The reason manufacturers prefer these materials is because of their environmental durability and conductivity.
There are endless numbers of materials that you can use for a Flexible Printed Circuit board. However, it is imperative to ensure that the material has the ability to come up with the defined criteria. An experienced PCB manufacturer, KingPCB, knows that good material should have chemical, capacitance, current, and mechanical resistance. It should have the ability to withstand extreme temperatures and should meet the functional needs of perfection.
KingPCB tends to take all these critical requirements into consideration before they design and develop any type of Printed Circuit Boards.
Different situation requires different types of Printed Circuit Boards
Being an outclass PCB manufacturer, we often come across these questions. Our clients want to know when should they use a Flexible Printed Circuit board and when should they opt for a Rigid Printed Circuit Board.
Several factors influence the decision such as the budget, the timeline, the requirement of the electronics and much more. You need to pay close heed to all these factors before making a decision.
A Flexible Printed Circuit board will cost you more in comparison to the Rigid Printed Circuit Board. However, if we talk about the total cost of ownership, we do believe that Flexible PCB would cost you less, as they are widely used, instead of the Rigid PCB.
We simply cannot deny the fact that the use of Rigid PCB is limited. In order to, fully understand the total cost of ownership, you first need to focus on how Flexible PCB tends to eliminate some unwanted costs.
Due to Flexible Printed Circuit boards, you do not need additional components including wire harnesses, connectors, and other circuit boards. So, when you actually remove all these components from the material cost, labor cost, design, scrap cost, and assembly cost, you will notice a mark difference in the price.
The cost is bound to go down. However, we still come across several electronics including audio keyboards, computers, desktops, laptops, solid-state drivers, children toys, Flat-screen TVs and other electronic gadgets using Rigid PCB. The reason being, they find them more cost-effective and efficient.
Nonetheless, we do see Flexible Printed Circuit boards in high-performance devices, ultra-compact electronics. Some examples include smartphones, GPS units, iPods or Tablets, wearables, and cameras.
If you are thinking that greater sophistication is the reason for using Flexible circuit boards, then we have to correct you. Some low-tech and under-the-counter technology tends to use these flexible boards as well. For instance, you will see them in LED light.
If you are looking for the best of both worlds, we would suggest that you use both the Rigid as well as the Flexible Printed Circuit Board together. The unified PCB will provide you with outstanding results and it will offer endless capabilities.
Differences and Similarities between Flexible and Rigid PCB
Both Flexible and Rigid Printed Circuit boards have some differences as well as similarities. Of course, they tend to serve the same purpose, thus they are bound to have some similarities.
Design
In terms of design, we do not see many similarities between the two circuit boards. In the case of a Rigid Printed Circuit board, a cheap PCB manufacturer needs to follow certain design rules. The manufacturer has to have a minimum hole size, along with a minimum distance to the board edges. Likewise, it needs to ensure that the board has a minimum space and trace width along with a minimum copper layer and the overall design thickness.
Manufacturing
There might be little similarity in the designing phase; however, you will see a lot of similarities in the manufacturing process. Both the Rigid and the Flexible PCB tend to share several processes including photo imaging, photo development, plating Vias, plating holes, drilling holes, etching of copper traces, planes, outlines, and pads and heating of the circuit board.
Once the above steps are completed, both Rigid and Flexible Printed Circuit board takes on a different direction in the manufacturing process. Flexible PCB head to the coverlay station, whereas the Rigid Printed Circuit boards, head towards the solder mask station.
Flex Circuit Overlay
To protect the internal circuitry of the Flexible Printed Circuit board, the PCB manufacturer uses the Flex Circuit overlay process. You might be familiar with the term Coverlay, it basically is Flexible Circuit Overlay.
We can say that a Flexible Circuit board Coverlay film is something like the Rigid solder mask. However, there is one major difference. In the case of a solder mask, the layer is rigid, whereas the coverlay film offers flexibility.
Generally, the manufacturer uses a thermoset adhesive to coat the polyimide film. The thickness of the film varies. It can range from .0005 to .005 or with .001 and .002. These are the most common ranges, but you can find other ranges as well.
Softness
A good PCB manufacturer understands that a standard flexible circuit board requires good flexibility. They also know that for a Flex circuit board, it is imperative to have a three-dimensional space. After all, the PCB has to bend and offer flexibility to the applications.
Unlike the Rigid Board, the Flex Circuit board saves space. It also has the ability to reduce the board layer. They can withstand high temperature and they are excellent for applications that require compressions.
Application of Flexible and Rigid Printed Circuit Board
Both Flexible and Rigid Circuit boards offer different benefits. Rigid Circuit boards are still commonly used around the globe. They have been around the corner for years now.
However, as the consumer demand for small-sized electronics increases, the PCB developers are finding it challenging to come up with small size Rigid Printed Circuit boards. The engineers are finding it difficult to face the challenge of decreasing the size at the same time increasing the performance.
This continuous demand for smaller and small electronics is forcing the manufacturer to opt for Flexible Printed Circuit Board instead of the Rigid boards.
Due to the size and performance of Flexible Printed Circuit boards, they are ideal for mobile consumer electronics, implants, medical devices, and sensors. Their ability to fit the weight and the size of smaller devices is making them extremely popular among the electronics industry.
We would recommend Flexible Printed Circuit boards to the following products and services
- Vibration resistance
- Shock resistance
- Less number of device interconnects
- Three-dimensional packing geometry
- Reducing the size of exciting technology
- Products that are light, weight, and thin, yet they offer durability
- Perfect replacement for wiring solutions where Rigid PCBs are unable to fit
Read More about: Printed Circuit Boards Importance
High Density and High-Temperature Applications
Flexible Printed Circuit boards are excellent choice applications that are offer durability while keeping a close check on the size and the weight. Engineers tend to use Flexible PCB for industrial as well as manufacturing applications that have the capability to withstand high temperatures and offer chemical resistance.
In addition, these applications should be able to withstand UV exposure at the same time deal with different radiations as well. Flexible circuit boards offer heat resistance because of the material that is being used in them. They typical have polyimide or something similar to polymer in them.
These kinds of materials are excellent heat dissipaters. However, PCB manufacturer does not use polyimide or similar material for Rigid PCB, thus they cannot offer the same heat resistance capability.
Due to this reason, products that would be encountering extreme conditions will use Flexible Printed Circuit boards in order to avoid the negative impact on the product’s performance. One good example is the industrial sensor technologies.
Efficient Applications
Even today, we tend to see Rigid Printed Circuit boards in most of the electronics. They are the consumer’s first choice, mainly because they are cost-efficient. So, if your objective is to cut down on the cost of your application development, Rigid Printed Circuit Board should be your first choice.
For a large number of productions, we recommend you use Rigid PCB as they would cost you less. Of course, if there is a technical reason for using the Flexible Printed Circuit Board, you should not use Rigid then.
How to choose between Flexible and Rigid Printed Circuit Board
As we have discussed above, different applications have different requirements, thus they require different Printed Circuit boards. For instance, it would be wise to use a Rigid Printed Circuit Board in large products, such as desktop computers or Television. However, in the case of Flexible boards, you should use them in smaller application including wearable technology and smartphones.
So, when you choose between the Flex and Rigid PCB, the first thing that you need to consider is the demands of your application. You need to focus on your industry’s preferred circuit board type and impact one of the other types of Printed boards can have on your profit.
Choosing the right circuit board is imperative, however, equally important is to select the best supplier. Choosing the best supplier can be troublesome, especially when you have several cheap PCB manufacturers offering their services. You need to be wise and make the right decision.
At KingPCB, we offer the finest quality circuit boards. We provide both Flexible as well as Rigid Printed Circuit boards. Our years of experience and our expert designers and developer ensure the highest quality possible. We are the best in our industry, and it is extremely difficult to meet our competitive prices. You can reach out to us around the clock and we will assist you in the best possible way.
To sum it up
Despite the fact that both Flexible Printed Circuit Board and Rigid Circuit board fundamentally serve the same purpose, yet both are used in a different application at different times. They both connect different mechanical and electrical components, but the applications using them differently.
If you plan to develop an application that is of small size, but it has to withstand extreme heat, the Flexible Printed Circuit board should to your first choice. The material used in the Flex board allows them to resist chemicals, it can withstand extreme heat and they produce efficient results.
On the contrary, applications that require efficiency and their size do not matter use Rigid Printed Circuit Boards. In order to enjoy the efficiency of Rigid boards along with the flexibility of Flex circuits, we recommend that you opt for the hybrid. The Rigid-Flex boards tend to have the best of both worlds. It offers the functionality of a Rigid board, whereas, it can bend and used in small-sized electronics.
Lastly, it is important to know that all Printed Circuit board houses have the capability to manufacture high-quality Flexible Printed Circuit boards. Therefore, you need to choose wisely. KingPCB is perhaps one of the best options when it comes to choosing the right supplier for not only Rigid, or Flexible printed board, but also for the hybrid Printed circuit boards.
