Method for making a wafer level aluminum nitride substrate
Disclosed is a method for making a pure aluminum nitride substrate. At first, aluminum nitride is mixed with a water-resistant material and an adhesive material. The mixture is made into grains in a granulation process. The grains are molded into a nugget in a steel mode by hydraulic pressure. The nugget is subjected to a cold isostatic pressing process. At a low temperature, the water-resistant material and the adhesive material are removed from the nugget. Then, the nugget, boron nitride and nitrogen are introduced into and sintered in an oven, thus providing a pure aluminum nitride substrate. The purity and quality of the aluminum nitride substrate are high. The aluminum nitride substrate can be used in a light-emitting diode. The method is simple, the yield is high, and the heat radiation of the aluminum nitride substrate is excellent.
1. A method for making a pure aluminum nitride substrate including the steps of:
providing aluminum nitride powder;
adding calcium silicate and an adhesive material into the aluminum nitride powder and granulating the aluminum nitride powder into aluminum nitride balls;
providing hydraulic pressure for molding the aluminum nitride balls in a steel mold to provide an aluminum nitride nugget;
cold isostatic pressing the aluminum nitride nugget;
removing the calcium silicate and the adhesive material from the aluminum nitride nugget at 400° C. to 600°C.; and
introducing the aluminum nitride nugget, boron nitride powder and nitrogen in a boiler for sintering.
2. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the adhesive material is PVB.
3. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the granulation is executed by pelletizing.
4. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the granulation is executed by screen.
5. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the hydraulic pressure is 10 to 650 tons to mold the aluminum nitride balls into the aluminum nitride nugget.
6. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the cold isostatic press is conducted under hydraulic pressure of 5000 to 80000 PSI.
7. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the boiler includes a heating mechanism.
8. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the aluminum nitride nugget, the boron nitride powder and the nitrogen are introduced into a sintering box before they are introduced into the boiler.
9. The method for making a pure aluminum nitride substrate in accordance with claim 1 , wherein the nitrogen is introduced into the boiler when the temperature in the boiler reaches 1800° C. ±20%.