Ceramic aluminum laminate and thermally conductive adhesive therefor

A reworkable silicone free heat sinked ceramic circuit board having a surface of an area of at least ten square inches and capable of withstanding temperature cycling in the range of -60.degree. C. to 125.degree. C., vibration and humidity without delaminating, comprising:

• a flat ceramic board having a surface of an area of at least ten square inches;
• a flat aluminum sheet having a surface area sufficient in size and geometry to at least cover said surface of said ceramic circuit board;
• an epoxy adhesive intermediate said board and said sheet;
• said epoxy adhesive holding said board and said sheet together and forming therewith a laminate and said epoxy adhesive being of sufficient flexibility characteristic to prevent delamination due to thermal stress at all temperatures within the range of -60 degrees Centigrade and 125 degrees Centigrade and being thermally conductive for permitting transfer of heat between said ceramic board and said aluminum sheet and having a dielectric constant of at least 3 at 1 MHz with said epoxy adhesive have the characteristics as follows:
• Hardness, Shore A of at least 70;
• Volume Resistivity @ 75.degree. F. (ohm-cm) of at least 3.times.10.sup.13 ;
• Dielectric Strength (volts/mil) of at least 400;
• Dielectric Constant @ 1 MHz of at least 3.1;
• Thermal Conductivity (BTU-in/hr. ft..sup.2 .degree.F.) of at least 3;
• Coefficient of Thermal Expansion (per .degree.F.) of not more than 73.times.10.sup.-6 and Young's Modulus, Tensile of at least 290,000.