AUXILIUM INTERNATIONAL S. R. L. Italy

The larger the power density is, the higher the thermal conductivity and the lower thermal resistance of aluminium base copper-clad laminate are required; The larger the current-carrying capacity, the thicker the circuit layer of aluminium base copper-clad laminate(copperfoil) would be; The dielectric breakdown voltage of aluminium base copper-clad laminate shall comply with isolation requirement of modulus electrical apparatus; It must keep a minimum isolation shelter between the edge of circuit board(orone hole on circuit board) and the nearest conductor, it generally is the material thickness plus 0.5mm; During machining of aluminium base copper-clad laminate, such as drilling, punching and cutting, be carefully not to break or pollute the dielectric layer closely near conductor; As the rapid development of electronic industry, the requirement for the flatness of finished PCB is becoming higher and higher. The bow, twist and flatness of aluminum base copper-clad laminate PCB is affected by the design and quality of punching and cutting machines. There is also an effect from the differential coefficient of expansion among circuit layer, dielectric layer and base layer. This effect is determined by the thickness ratio of circuit layer(copperfoil) to base layer, the larger the ratio is, the bigger the bending is. If thickness of copper foil is less than 10% that of base layer, the base layer(aluminumsheet) will occupy the leading position in mechanical property and the flatness of PCB is satisfactory. If more than 10%, there will be some bow. For aluminum base copper-clad laminate PCB, there is always some bow caused by the difference in temperature coefficient of expansion between the circuit layer and base layer. The bow of a finished part is also dependent on the amount of copper remaining on the part and the width of the lines. If the lines are arrow enough, the stress caused by the coefficient of expansion is absorbed in the dielectric.