Patent ID: 7908884

Claim:
A method for bonding a first plate to a second plate comprising the steps of: providing a first bonding material, a second bonding material and a third bonding material on the first plate so that the first bonding material is located between the second and third bonding materials, wherein the first bonding material is thicker than the second and third bonding materials; providing the second plate on the first bonding material; heating the first and second plates and the first, second and third bonding materials to the softening point of the first bonding material; exerting a load on the first bonding material to reduce the thickness of the first bonding material to that of the second and third bonding materials and transfer the load to the second and third bonding materials from the first bonding material; raising the temperature to the crystallization point of the first bonding material and keeping the temperature at the crystallization point of the first bonding material; and raising the temperature to the wetting point of the second and third bonding materials to wet the interface between the first plate and the first, second and third bonding materials and the interface between the second plate and the first, second and third bonding materials so that the first, second and third bonding materials will firmly bond the first and second plates together when they cool down, wherein the melting point of the first bonding material is higher than that of the second and third bonding materials.