As the demand for smaller and lighter devices increased, PCB developers embraced the task of manufacturing high-performance boards with minimum size and form to satisfy the needs of the customers and clients alike. This led to the development of a number of smart PCBs. At present, the most commonly used PCBs are flexible PCB and rigid-flex PCB. However, the latter is preferred over the former as a rigid-flex PCB provides better reliability and durability, reduced weight, high-strength, and time and cost-effectiveness.
It would not be wrong to say that the flexible PCBs have accrued worldwide acceptance in many domestic and commercial industries and applications because of their functional versatility. But they have certain disadvantages like assembling PCBs, high initial cost, less resistant to temperature, serious issues pertaining to design, and difficulty in repair & maintenance. Hence, a rigid-flex PCB is mostly used instead of a flexible PCB. The latter includes characteristics of both rigid and flexible boards. A rigid-flex PCB can also be surface mounted easily on both sides.
Difference between a flexible and a Rigid-Flex PCB?
A Flexible PCB, also known as flex printed circuit boards, is made from circuits and parts that employ any flexible material. It often contains a protective cover layer. On the other hand, a rigid-flex PCB is manufactured by combining the technologies of both flexible and rigid boards. It is manufactured by joining various layers of flexible circuit substrates to one or more rigid circuits. The connections can be either internally or externally or both which depends upon your requirement. It gives the shape of a spring that can be compressed or stretched.
Reasons We Use Rigid-Flex PCB
Generally, a Rigid-flex PCB is preferred over a flexible PCB since:
1. Reliability and Durability
Reliability is the most important consideration for electronic devices. A rigid-flex PCB offers high connection reliability compared to a flexible PCB because of fewer solder joints. Also, due to the presence of complex mechanical designs, it is more durable than a simple flexible PCB. That?s why the former is used effectively for optimized housing solutions.
2. Qualities of both Circuitry
We know that a rigid-flex PCB consists of both rigid and flexible layers, so it has the flexibility to fit into any device. Plus, we can increase its rigidity according to our requirements. In other words, it provides both mechanical support/rigidity and flexibility at an optimum level without the risk of breakdown. Its corners are made flexible to fit into any device. Contrarily, a flexible board is designed specifically to offer enough flexibility and bending resistance.
3. Repair & Maintenance Work
Repair and maintenance of a flexible PCB is very complex and difficult as it requires a complete overhaul of the base map. A protective layer covers/protects its surface that needs to be removed to do any repairs and then put back after the repair work. So, it becomes a costly and complex process. On the other hand, it is very convenient to do any routine repair and maintenance work in a rigid-flex PCB. Its all components are clearly labeled and the technician can easily assemble or disassemble them if need arises for repairing.
4. Assembly Process
The assembly process of a flexible PCB is complex and costly because of the poor utilization of the panel. It includes repeatable installation and wire routing making it a difficult process. On the other hand, a rigid-flex PCB has a simple assembly process and all its components can easily be identified and re-worked.
5. Resistance to Temperature and Aggressive Conditions
A flexible PCB can provide sufficient resistance to temperature, but at high temperatures, its performance is seriously affected. But a rigid-flex can withstand sufficiently high temperatures, harmful chemicals, and damaging oils. It also offers more resistance to UV and other deleterious radiations. So, it is always better to choose a rigid-flex PCB.
Most flexible PCBs are manufactured to fulfill specific requirements, and hence the initial cost of circuit design, and layout to develop the final product is relatively high. However, rigid-flex PCBs are cost-effective due to the fewer number of parts, connections, and assemblies required.
A flexible PCB is vulnerable to internal and external damages due to less rigidity, especially during improper handling of the operation. Hence a professional technician is required for its soldering and repair. While a rigid-flex PCB offers a significantly high degree of resistance to damages.
In a nutshell, it can be said that Rigid-Flex PCBs offer a wide array of advantages over a flexible PCB, be it higher reliability, durability, cost-effectiveness, resistance to temperature, and other aggressive conditions. That is why the majority of smart control and high-performance electronic systems employ rigid-flex PCB.