Keyword: pcb board, PCB, circuit board, printed circuit board design , printed circuit board
Most of the rigid printed circuit board design element has been used in the design of the flexible printed circuit board in the . However , there are other new elements requires attention. 1. conductor current carrying capacity Since the flexible printed circuit board is poor heat dissipation ( rigid printed circuit board and comparison ) , pcb board it is necessary to provide sufficient wire width . Figure 12-8 shows the current more than 1A , select the wire width principle. Some conductors carrying large currents when placed adjacent to each other face to face , or take into account the heat concentration problems , must be given an extra wire width or spacing. 2. Shape No matter where in the case of possible rectangle should be preferred , since this can save a good substrate. Near the edge margins should allow enough freedom , which according to the remaining space of the substrate may be pcb board.
In shape , the interior angle should look round ; pointed angles may cause the tear panel . Smaller wire width and spacing should be minimized as much as possible . If the geometry space permits, closely spaced thin wires should become wide wires. In the plated through-hole pcb board or mounting hole components should be terminated at the wire smoothly through search to pads . As a general standard , like any angle from a straight line or a different line widths to change , must be as smooth transition. Sharp corners will stress the natural concentration , causing lead failure . 3. Flexibility As a general standard , the bending radius should be designed to be as large as possible pcb board. The use of thinner laminates ( example: instead of 125m with 50m copper foil ) and wide wire , can better withstand more cyclic bending improve its possibilities . For a large number of bending cycles , single-sided flexible printed circuit board usually shows a better performance.
4. Pad Around the pad , from the flexible material to a rigid material changes. This area of the conductor more easily damaged . Thus , the pad should be avoided in the area prone to bending . The general shape of the pad should be like a teardrop-shaped , film must be able to cover the bonding pads sewn .
5. rigid reinforcing plate In the small electronic devices ( such as small calculators ) of mass pcb board , the combination of the reinforcing plate are deadlocked rigid laminated flexible printed circuit board has become very popular, and its cost is also more optimized. Soft Of printed circuit board is equipped with a suitable slot in a rigid board ( for example, grade G-10) , and to facilitate the subsequent separation . After assembly and wave soldering components , the rigid plate by cutting into different parts , so that the folded into the desired shape. The special design of the flexible board asked to indicate only a few steps , less than rigid plate design . However, the important design differences must remember : Three-dimensional flexible printed circuit is very important, because bending and flexible applications can save space and reduce the board layers. Compared with the rigid plate , flexible board for less demanding tolerances , pcb board allowing for greater tolerance range. Because wings can be bent , they are designed slightly longer than required . In order to minimize the cost of the circuit , the following design techniques should be considered: Always have to consider how the circuit is assembled on the panel . Circuit to be small , you should pcb board consider using a series of small circuit instead of a large circuit . Whenever you use must follow the recommended tolerances. Place only in the necessary design element bonding area . If the circuit is only a few layers , then use the enhanced comparable rigid flexible printed circuit board is much cheaper . In every oz of copper materials ( including copper plating ) , specify the use of 0.0001 in the binder . Manufacturing unsheltered pads and no overlay circuit pcb board , sometimes cheaper .
