The characteristics and advantages of printed circuit board have been enhanced over time. The advancements in the technology, reduction in size and fast processing speed compare to conventional devices have made PCB’s preferable in most of the applications.
Across the globe there are two types of circuitry and boards which have vast applications and their manufacturing is been done on a large scale. Flexible PCB’s and flex PCB are different from the traditional rigid PCBs. What makes them flexible is the combination of flexible and rigid materials. The flex boards are rolled with copper which provides sufficient bending resistance and flexibility.
Flexible printed circuit Board:
There are multiple reasons to call these boards as flexible, but the first and foremost reason is the design of the circuitry which can be easily matched with the electronic device’s requirements. On the front of weight, portability and durability flexible printed circuit boards are remarkable. Sometimes there are a product’s limitations with flexible boards. The board size is required to be decreased or like replacement of circuit or redesigning. In these cases all circuitry need to be laid out in a distinct pattern entirely and then treated with a malleable base metal, like copper. This method was also used in past, but the material is heavy and rigid and had not been able to serve the flexibility. Here are some pros and cons of flexible circuit boards are mentioned below:
- 1- Absence of mechanical connectors like the traditional printed circuit boards. This increases the reliability of the flexible printed circuit board.
- 2- Because of such technological advancements the cost of the board has also increased.
- 3- It has moderate temperature resistance, because of the material properties.
- 4- It can be accommodated to any design because of flexibility.
- 5- Better for rapid replacement.
Flex-Rigid printed circuit Boards:
As its name depicts it is combination of flexible and rigid circuitry. Flex-rigid printed circuit boards are usually of multilayer type and generally more than the conventional one. For different applications additional conductive layers with proper rigid and flexible insulations depending upon the requirement. Outer layers are usually rigid and they have pads for safety, and those layers can be in many numbers.
The manufacturing technology used in making of rigid-flex boards and the materials used decides its credibility. Like dimensional stability of polyimide is lesser than FR-4.Therefore to take care of this material shrink proper standards are required to be taken. In advanced research it was found that reinforced flexible boards can be used instead of flex-rigid printed circuit boards. This is because in general applications which are of use in day to day life, has increased. And buyers are reluctant for this. On the other hand in medical equipments cost is not big concern where technological advancement is more important the use of flex-rigid printed circuit boards is appreciated. As far as cost is concern the designer must involve the manufacturing unit in the initial processes so that utilization of raw material, proper material selection and decision on manufacturing process can be taken appropriately by considering various aspects.
Conductors of the printed circuit board deployed on the primary layer which is rigid. Rigid-flex printed circuit board has a wide range of applications like now they are present in many electronic devices of our common use. It is also used in high end control systems. A range of medical devices and smart devices are using rigid-flex PCBs. As far as medical instruments are concern rigid-flex PCBs is very important since it can bent and folded in a very small space available, Pacemaker is one of its example. Some applications still required conventional printed circuit boards because of their own specifications. But at present most of the devices have demand of flex-rigid printed circuit boards. Some pros and cons of Flex-rigid printed circuit board are mentioned below:
- 1- Flex-rigid printed circuit boards are built up with less solder joint. Hence it increases its reliability during operation. Flex-rigid circuit boards can fit anywhere because of their exceptional characteristics.
- 2- It has lower cost compare to the flexible printed circuit board.
- 3- Compare to flexible printed circuit board the flex-rigid PCBs have good temperature resistance. Polyimide has good thermal stability.
- 4- Flex circuits lower weight and ductile nature reduce the impact of shock.
- 5- Flexible circuits allow narrow lines provide way to high density. Flex circuits also offer good resistance to ultra-violet radiation.
- 6- Flex circuit also eliminate errors associated with wire routing. Hence reduces the testing time and reworking.
- 7- Replacement characteristics are not quite good.
- 8- Because of fewer interconnections the operation of flex-rigid printed circuit board is more reliable.
- 9- Maintenance cost is minimum for flex-rigid board.