Thermal Insertion
Component mounting represents a specialized board fabrication sequence where threaded brass eyelets or threaded inserts are pressed into pre-drilled circuit board substrates before final wave soldering. The insertion phase specifically governs the mechanical downward stroke that seats the metal hardware into the laminate. Mechanical presses apply controlled downward pressure to drive the knurled exterior of the insert into the rigid fiberglass material.
Shear forces between the knurled metal and the surrounding resin create friction that secures the hardware against rotational torque. Production engineers monitor insertion depth closely to prevent board cracking and resin delamination around the mounting hole.
Torque Resistance
Joint integrity depends heavily on the radial grip established during the pressing stroke. Axial loads applied during subsequent chassis assembly test whether the insert withstands specified twisting limits without stripping the internal threads. Shear stress concentrates along the outer diameter where metal contacts the glass epoxy matrix.
Over-pressurization deforms the barrel and cracks the surrounding dielectric substrate, which ruins the entire assembly before component population begins. Correctly calibrated pneumatic presses halt downward travel the moment the flange sits flush against the top copper plane.
Failure Analysis
Microsectioning reveals internal voids and resin starvation caused by incorrect hole diameter or excessive press velocity. Cross-sectional inspection under optical magnification exposes copper barrel splitting and inner layer separation resulting from hydraulic shock during the seating stroke. Destructive torque testing isolates process variations by measuring the exact rotational force required to spin the brass hardware out of the cured laminate.
Preventive maintenance schedules require regular replacement of worn pilot pins to maintain perpendicularity throughout continuous production runs.
