PCB Tech - Flexible circuit board layout and optimization plan

Integrate all the data of the flexible circuit board (mechanical matching, design criteria, circuit type and geometric structure interconnection form), and make a paper pattern at the same time to conduct matching and follow-up inspections:

1. Whether the terminal area is wide enough to meet the number and size requirements of the circuit;

Second, it is possible to concisely carry out reasonable mechanical matching for use and assembly, calculate the number of lines and multiply the line width and spacing, and then calculate the minimum width of the flexible circuit board according to the electrical requirements;

Third, the line width bottleneck lies in the problem of mechanical collocation, which determines the maximum number of lines in a single layer and also determines the number of layers in the overall design. At this time, there is a small problem: the resistance is a function of the average width of the circuit. If the bottleneck area is short, the circuit can be reduced to compensate for the conductivity by passing more lines in a single layer and increasing the width in other areas. In this way, it should be understood that when the multi-layer flexible circuit board is to be bent under a radius, the outer layer must be designed to be longer to compensate for the larger channel length. This part is called the advanced stacking design;

Fourth, keep all connections on a single flexible circuit board;

5. The entire bundle of lines are designed in a similar way (high current lines are designed in high current mode, sensitive lines are designed in a sensitive way), etc.;

Sixth, review and optimize the overall layout, folding processing, advanced design, hinges, and closeness in use until a good shape is established. Make copies and connect them in series to determine how many finished flexible circuit boards can be filled into the production board to estimate the cost. An effective design will have a high line density, so it can be expected that the connector area layout will see bottlenecks. An idea is to estimate the number of flexible circuit boards in the early stages of development, and these flexible circuit boards can be made with connection terminals on each layer, and then the size of the pattern is also designed based on this number.

Keeping the circuit in the correct sequence and gradually changing into a dense area is a headache problem faced by flexible circuit board designs. In most cases, designers cannot configure the pins or contacts very freely and flexibly. In the practical world, flexible circuit board design can only be added later in the product plan. Most of this happens after the line connection configuration has been decided, and there is little chance that it can be re-arranged. There are bound to be many situations at this time. The left line must reach the right plug or contact. PTH is a more general solution, which allows the use of inter-layer connectivity to reconfigure the contact relationship. For designers who don't want to use PTH, the available solutions include external folding, reflex folding, double-sided patch cord combination, and through connection.

From a design point of view, the design of a piece of flexible circuit board is quite particular, but relative to the unit flexible circuit board, it also requires a relatively high cost to construct. It is more effective to improve production efficiency, and therefore it is cheaper to implement. What needs to be reminded is that if technology and quality standards allow multiple contacts to be combined on one terminal, the design can break the complex circuit design, simplify it to a separateflexible circuit board and use more popular terminals. The flexible circuit boards of relatively small pieces can be configured into groups according to the type to facilitate and test, which can further reduce the cost.