When selecting fiberglass boards, you must prioritize mechanical strength, dielectric constants, and thermal stability. For electronic applications, ensure a Dielectric Constant (Dk) of 4.2-4.8 and a Dissipation Factor (Df) below 0.02. For structural use, verify the Flexural Strength (typically ≥340 MPa) and Water Absorption rate (should be <0.10% to prevent delamination). Always confirm the TG (Glass Transition Temperature); standard boards are 130°C-140°C, while high-reliability applications require High-TG boards (>170°C) to withstand lead-free soldering or extreme environments.