Inorganic Additive
Microscopic particles of silicon dioxide are blended into epoxy resin systems to lower the coefficient of thermal expansion of a circuit board laminate. Adding silica fillers also increases the thermal conductivity of the substrate, helping to dissipate heat away from active components. This material modification is a standard practice in the production of laminates designed for high-power or high-reliability applications.
Mechanical Influence
Resin stiffness is enhanced by the presence of these hard particles, which reduces the mechanical strain on soldered joints during thermal cycling. However, the presence of these abrasive particles increases the wear rate of mechanical drill bits, requiring shorter drill change intervals during manufacturing. The modified resin composite also exhibits higher resistance to moisture absorption, which reduces the likelihood of blistering or delamination during high-temperature reflow soldering.
For instance, in halogen-free laminates, these additives are required for achieving the required flame retardancy without compromising the electrical performance of the cured board.
Drilling Wear
High abrasion rates from these fillers can cause drill bit deflection, which can lead to drill breakage if the drilling parameters are not properly controlled. Fabricators monitor drill life closely and use diamond-coated or specialized carbide drill bits when processing these filled materials.
