Bending Resistance
Structural stiffness against transverse loading determines how much a printed circuit board will flex when supported at its edges. The flexural rigidity depends on both the elastic modulus of the materials and the moment of inertia of the cross-section. This property is required for boards that must withstand the pressure of connector insertion or the weight of heavy components.
Thickness Influence
Changes in the thickness of the board have a cubic effect on its resistance to bending. A small increase in the dielectric height raises the flexural rigidity, making the assembly much more stable during the high-speed movements of a pick and place machine. This relationship means that thin boards require additional support or stiffeners to prevent damage to solder joints during handling and transport.
Using a thicker core material is the most direct way to increase the rigidity of the assembly.
Mechanical Support
Calculating the deflection of a board under its own weight or under functional loads allows engineers to design appropriate mounting points and enclosures. High flexural rigidity reduces the risk of fatigue in surface-mount components by limiting the strain at the solder interface. The property is measured using a three-point or four-point bending test to verify that the finished product meets the structural requirements of the application.
