Maintaining Traceability Throughout Flexible Circuit Boards
Traceability Throughout Flexible Circuit Boards
Rigid-flex and flex circuits are used in a wide variety of products such as calculators, printers, cell phones and LCD televisions. However, they are also utilized in more complex applications such as medical treatment devices like heart monitors and pace makers, industrial control equipment, aerospace/military products and so on. These types of applications demand a high degree of durability and flexibility from the PCB. The challenges of this require a very specific approach when designing the copper pattern, placing and routing components on the board and ensuring that the board can meet the required physical characteristics.
During the fabrication of a Flexible circuit board, it is common for the material to move and shrink slightly. This can have a negative impact on the integrity of a Printed circuit board. It is therefore very important to always keep the minimum allowable bending radius in mind when designing a flex circuit. This will help to ensure that the traces and other metal structures are not compromised during the manufacturing process.
Another important issue to consider is the amount of time a flexible circuit board will be in a bent position. The amount of flexing will depend on the product design and the environmental conditions it will be exposed to. For example, a flex circuit that will be exposed to moisture and chemicals needs to have a higher minimum bend radius. While a flex circuit that will be in a static position such as a flat panel display can have a smaller maximum bend radius.
Maintaining Traceability Throughout Flexible Circuit Boards
In addition, when a flex circuit is in a bent position the conductors can experience different types of stress. To minimize this stress, it is recommended to use plated through-holes in a flex circuit. This will reduce the stress on the flex circuit and make it more durable in a bent position. The other recommendation is to avoid tight bends in a flex circuit. Tighter bends increase the likelihood of damage to the conductors in the circuit.
Another area to be careful with is the layout of the flex circuit layers. It is important to maintain traceability throughout the entire flex circuit layer stack. This is achieved by not changing the trace width or pad entry and exit points between layers. This will prevent signal crosstalk and other issues that may occur if the traces are not properly arranged.
It is also very important to ensure that the flex circuit is stiffened to a point where it will not warp during the assembly process. This is accomplished by adding stiffeners to the corners of the flex circuit, as well as the edges. This will make it easier for automated pick and place machines to handle the flex circuit and will ensure that there are no problems during assembly, testing and final packaging. In addition, the stiffeners will also help to ensure that the flex circuit will not be damaged by the vibrations during transportation and handling. This will help to improve the reliability of the flex circuit and reduce the cost of production.