Dimensional Stability: Dimensional Stability. Dimensional stability refers to the amount of change in the length, width, and flatness of a sheet that is affected by changes in temperature, humidity, chemical treatment, aging, or applied pressure. Expressed as a percentage. When the board warp occurs, the PCB board surface is deducted from the vertical highest point of the reference plane (such as the marble platform), that is, its vertical deformation, or directly measure the hole with the steel needle to measure the board floating. height. The amount of this deformation as a molecule, and then the length of the board or the length of the diagonal parent when the component, the resulting percentage is the scale of the stability of the unit of expression, commonly known as "size stability."