The invention discloses a method for preparing a high
phase ratio electric leakage resistant tracking index leadless compatible composite base
copper-clad laminate CEM-3, which comprises the following process steps: using low brominated
epoxy resin /
phenolic aldehyde as a main curing agent, adding a filling material to prepare core material glue impregnated
glass fiber paper, and preparing a core material by making the
glass fiber paper in a semi-solidified state at a temperature of between 130 and 210 DEG C; adding aluminum
hydroxide or
magnesium hydroxide as the filling material into the
epoxy resin /
phenolic aldehyde to prepare a plus material glue impregnated
glass fiber cloth, and preparing the plus material by making the glass
fiber cloth in a semi-solidified state at a temperature of between 130 and 210 DEG C; and superposing 1 to 20 sheets of the core material, pasting the plus material on the surface of the core material, cladding a
copper foil on the plus material, and performing
hot press molding at a temperature of between 80 and 200 DEG C, a pressure of between 10 and 60 Kg / cm and a vacuum degree of -60 mmHg. The CEM-3
copper-clad laminate prepared by the method simultaneously has CT1 more than or equal to 600V, higher
heat resistance and excellent CAF resistance, and overcomes the defects that a CEM-3 plate prepared by the prior art has the CT1 between 175 and 249 V and poor
heat resistance and CAF resistance, thus the CEM-3 copper-clad laminate is more adaptive to long-term operations under wet conditions and has
high heat resistance and electric reliability.