How does tolerance affect productivity?

The yield of a fully assembled PCB or мантажу на друкаванай плаце is usually related to the construction of a large number of boards, which in many cases requires a transition from prototype to mass production. In other cases; especially for the specialized design of critical systems for aerospace, medical equipment and industrial applications, small-batch production is the final stage of manufacturing. Whether it is a small batch or a large batch, the goal of the final stage of PCBA production is a perfect choice of yield or zero board defects, so that it cannot be used as expected.

The PCB defect that may be the root cause of the manufacturing may be a mechanical defect. Such as delamination, bending or breaking to an unobvious degree, may distort the electrical operation; for example, contamination or moisture on or inside the board. The assembled circuit board will also be damp and contaminated. Therefore, it is best to employ PCB moisture-proof methods during and after manufacturing. In addition to defects that may not be found before the circuit board is installed and put into use, there are some obvious defects that can make the circuit board unusable.

The number of boards produced divided by the number of available boards is the yield. The difference is the number of defective boards that need to be reworked (other actions must be taken to correct small defects and bring the board into a usable state). For PCBA that cannot be corrected by rework, it may need to be redesigned. This may mean additional man-hours, as well as increased manufacturing and testing costs.

How to improve PCB tolerance

The importance of your choice Assembly service cannot be overstated. Making the right choice may be the difference between receiving boards designed to meet or exceed regulatory standards. IPC classification or not. Similarly, the benefits of DFM cannot be overstated for your PCBA development. Tailor-made decisions within PCB tolerances of CM equipment and processes ensure that your circuit board can actually be built. The constraints defined by the regulations establish acceptable limits for the CM’s DFM tolerance range. The PCB tolerances you choose must be within these ranges.

The absolute range of CM equipment in a specific manufacturing step defines its processing window. For example, the absolute minimum diameter of the drill hole defines the minimum width of the process window used to create the through hole. Likewise, the maximum hole width defines the maximum processing window width used to create a through hole. As long as these physical dimensions meet the legal requirements, you can freely choose any size within the range. However, choosing extreme conditions is the worst choice because it puts more pressure on the drilling process to make it more precise and the possibility of error is greatest. In contrast, the middle position of the selection process window is the best choice, with the least possibility of error. Therefore, minimize the possibility that the defect is severe enough to make your circuit board unusable.

By selecting PCB tolerances at or near the center of the process window for the manufacturing steps of the circuit board, the possibility of circuit board defects can be reduced to almost zero, and the negative impact of correctable process defects on yield can be eliminated.