Non-Newtonian Flow Dynamics in Thin Prepreg Dielectric Micro-Channels
Non-Newtonian resin flow inside thin prepreg micro-channels governs void formation, trace displacement, and dielectric thickness stability during high-pressure lamination.
Silica-Filled Epoxy
Composite Material
A thermosetting resin system containing microscopic particles of silicon dioxide provides enhanced thermal stability and lower moisture absorption for printed circuit substrates. Silica-filled epoxy is commonly used in high-reliability applications because the mineral fillers reduce the overall coefficient of thermal expansion. This material property protects the delicate copper interconnects from stress during temperature fluctuations.
Mechanical Property
The addition of these hard particles increases the stiffness of the cured board and improves its resistance to mechanical warping. In a silica-filled epoxy system, the particles act as anchors that prevent the polymer chains from moving as much when heated. However, the abrasive nature of the silica can lead to faster wear on the drill bits during the fabrication process.
Fabricators must use specialized bits and slower feed rates to handle the increased hardness of this material. Despite the processing challenges, this resin system is preferred for boards that will undergo multiple reflow cycles or operate in harsh environments. The improved thermal performance justifies the additional effort required in the machine shop.
Manufacturing Adjustment
Tool life management is a critical factor when working with these abrasive materials. If the silica-filled epoxy is not drilled correctly, the quality of the hole walls will be poor. This material choice is a standard solution for reducing the z-axis expansion of multilayer boards.