SAW duplexer metallizations for high power durability

The improvement on power durability of SAW filters in order to realize a SAW duplexer is described in this study on IDT metallization. Compared with the conventional single layer metallizations such as Al-Cu, the laminated films are found to show the higher power durability. Many kinds of laminated film were tested changing the material of the middle layer for three layered films of which the top and bottom layers were made of Al-Cu or pure Al. Among them, two types of films such as Al-Cu/Cu/Al-Cu and Al/Mg/Al showed the best power durability. Al-Cu/Cu/Al-Cu had a lifetime 250 times longer than that of current Al-Cu single film. Al/Mg/Al further had a longer lifetime than Al-Cu/Cu/Al-Cu. These three layered films are being successfully applied to SAW antenna duplexers of cellular phones, indicating sufficient power durability for practical use.