PCBs Accommodate For Bending Stresses
PCBs are essential to the modern world, powering everything from heart rate monitors and smartphones to rockets and smart watches. Their advanced high density interconnect (HDI) designs feature thousands of copper connections, enabling them to hold large amounts of electrical information and communicate with one another. This information is transferred through conductive copper paths that are printed directly on insulating substrates. While PCBs are used across numerous industries, they have unique requirements that must be taken into account to ensure their mechanical integrity.
As such, PCB manufacturers must take special measures to accommodate for bending stresses that can deform the board and compromise its performance. These measures include employing proper construction techniques and using tools to precisely measure the PCB’s dimensional accuracy. They also need to have the appropriate design software and hardware to accurately model rigid-flex and flex circuits. This allows them to accurately delineate flexible and rigid zones while managing layer stack-ups and ensuring proper connectivity between them.
The metallurgical properties of the substrate and copper foil are among the primary factors that influence a PCB’s ability to withstand bending and flexing. The pcb board construction industry has responded to these challenges by developing a variety of materials to accommodate flexible applications. For example, it’s now common to see rigid-flex PCBs made from aluminum or Teflon, allowing them to withstand bending and flexing operations without sacrificing the functionality of their electronic components.
How Do PCBs Accommodate For Bending Stresses?
To minimize signal distortion, designers need to strategically position vias within the flexible zone. This helps to minimize the length of conductive paths and prevents localized degradation that could compromise overall performance. Moreover, the distribution of vias should be consistent across the flexible zone to help avoid imbalanced current flow and impedance control.
Optimal copper stress reduction is achieved through best practices such as staggered traces on double-sided PCBs and avoiding overlapping conductive paths in the rigid zone. This minimizes the occurrence of mechanical stress that may lead to abrasion and cracking of the traces. To further increase durability, the use of a hatched copper pattern is advised. This reduces the amount of stress imposed on a trace at 0deg, 90deg, and 45deg angle directions.
PCBs undergo a number of processes during their manufacture, including high temperatures, mechanical cutting and wet processing. These steps can cause thermal stress, which leads to warpage in the resulting product. Fortunately, the dimensional accuracy of a PCB can be improved by using various types of measuring tools, from feel gauges to contour gauges and profilometers. It’s also possible to perform baking tests to determine the dimensional accuracy of the PCB. These methods can be time-consuming and expensive, but they offer the highest level of precision. In addition, PCBs are subjected to a variety of environmental conditions, which can also affect their structural integrity. This makes it important to test and analyze the results of any measurement tools to make sure they meet rigid-flex and flex specifications.
