Are you considering the use of flexible or flex-rigid PCBs in an upcoming device, product or prototype? Every device and every build begins with the core component: PCBs, or printed circuit boards. The type of PCB you choose depends on your application.
There are two major types of circuitry and boards used in industrial and large-scale manufacturing: flexible PCBs and flex-rigid PCBs. Both types differ from traditional, rigid PCBs. As you'd expect, these board types are designed using a combination of flexible and rigid materials and technologies. Flexible circuit boards are rolled with copper and similar materials, and the main goal is to provide sufficient flexibility and bending resistance. Flex-rigid PCBs, on the other hand, are built using a combination of the two technologies and have both flexible and rigid areas.
Flexible printed circuit boards are considered "flexible" for multiple reasons, but the most obvious one is that their circuitry can be designed to match up with the electronic device or core product. Manufacturers are not forced to create a product or casing around the board itself. Instead, they can adapt the board to fit an existing design. This is beneficial when creating components or hardware that feature orthodox designs. For instance, if you are concerned with the total weight, portability and durability of a particular device, conventional boards may be out of the question.
Flexible boards must sometimes be adapted to a product's limitations. For example, the board size may need to be decreased, and circuits may need to be moved or redesigned to match up with case specifications and dimensions. All circuitry is laid out in a distinct pattern — including components — and then highlighted by a malleable base material, such as copper. Traditional printed circuit boards are also rolled this way, except the materials used are much heavier and more rigid.
Flexible PCB Pros and Cons:
• Reliability: Excellent due to removal of mechanical connectors;
• Cost: Higher cost than rigid or flex-rigid;
• Temperature Resistance: Fair;
• Completely flexible and pliable;
• Can accommodate any design;
• Better for rapid movement and high-stress conditions;
Flex-Rigid Printed Circuit Boards
Flex-rigid PCBs derive their name from the fact that they use a combination of flexible and rigid circuitry areas. Like most printed circuit boards, flex-rigid boards have multiple layers but generally have more than conventional designs.
These additional conductive layers are outlined with rigid or flexible insulation depending on the product needs. Outer layers on a board — no matter how many there are — often contain exposed pads or covers for safety. Conductors are deployed for the primary rigid layer, while flexible plated through-holes are used for any additional layers both flexible and rigid.
Some projects call for using traditional rigid technologies and designs. Others have limitations that prevent manufacturers from using these larger, less flexible boards. For instance, mobile and portable devices would suffer if designed with standard boards. There are just too many moving parts and components that would perform poorly when subjected to certain conditions. Mobile devices need to be portable, lightweight and able to tolerate conditions like heat, cold and, at times, moisture.
Flex-Rigid PCB Pros and Cons:
• Reliability: Excellent due to reduced need for solder joints;
• Cost: Lower cost compared to flexible boards;
• Temperature Resistance: Excellent;
• Ideal for moderate to slightly higher than normal movement and stress;
• More flexible and pliable than conventional boards;
• Long-term reliability thanks to fewer interconnects and components;