Modeling Slip Velocity and Pressure Gradients across Smooth Copper Foils
Modelling slip velocity and pressure gradients across smooth copper foils prevents resin starvation and locks dielectric thickness tolerances during lamination.
Micro-Void Prevention
Quality Control
Eliminating small trapped gas bubbles within a solder joint ensures maximum electrical conductivity and mechanical strength. Systematic micro-void prevention involves optimizing the stencil design and the reflow profile to allow flux volatiles to escape before the solder freezes. These tiny holes, often less than 50 microns in diameter, can act as stress concentrators if they cluster in critical areas.
Control over these defects is especially essential for power electronics where voids impede heat dissipation.
Solder Geometry
Stencil apertures influence the volume of solder paste and the escape path for outgassing. For micro-void prevention, engineers often use window-pane patterns on large ground pads to create channels for the gas. This technique reduces the likelihood of large bubbles forming in the centre of the thermal interface.
Process Parameter
Vacuum reflow technology provides a physical mechanism to pull gas out of the molten alloy. This equipment lowers the ambient pressure during the liquid phase, causing any trapped micro-voids to expand and rise to the surface. Adjusting the soak time and the peak temperature also assists in micro-void prevention by ensuring the flux is fully activated and the solder is sufficiently fluid.
Final inspection via high-resolution X-ray confirms that the voiding percentage remains within the limits specified by industry standards.