Material Stiffness
Mechanical resistance defines the capacity of a structural component to withstand bending forces without suffering permanent deformation. The flexural modulus represents the ratio of stress to strain in flexural deformation, which defines the stiffness of the material. This parameter determines how effectively a polymer or composite substrate supports electronic components under mechanical loads.
Designers rely on this metric to select appropriate materials for circuit boards, ensuring that the assembly maintains structural integrity during high-acceleration events.
Load Response
Outer surface fibers experience maximum tension while the innermost layers undergo compression during a bending test. The internal structure of the material distributes these opposing forces across the neutral axis. This stress distribution creates a complex gradient that differs from uniform tensile loading.
High filler concentrations or reinforcing fibers increase this resistance.
Testing Standard
Standardized measurement utilizes a three-point loading system applied to a rectangular test specimen of specified dimensions. The flexural modulus is calculated from the slope of the initial linear region of the load deflection curve. ASTM D790 governs this procedure for unreinforced and reinforced plastics.
Application Limit
Environmental temperatures alter the physical response of plastic materials. High temperatures soften the polymer matrix, reducing the stiffness.
