Surface acoustic wave (SAW) device
View Patent ↗A surface acoustic wave (SAW) device having improved moisture resistance is provided. The device includes a piezoelectric substrate, an interdigital transducer (IDT) electrode on a first surface of the piezoelectric substrate, and a resin coating for covering the IDT electrode. After a piece of resin material of the resin coating is dipped in an amount of pure water as solvent having a mass as 10 times great as the piece of resin material at 120° C. under 2 atom pressure for twenty hours, a concentration of chlorine ion in the solvent is not higher than 50 ppm.
1. A surface acoustic wave (SAW) device comprising:
a piezoelectric substrate;
an interdigital transducer (IDT) electrode on a first surface of said piezoelectric substrate; and
a resin coating for covering said IDT electrode,
wherein, after a piece of resin material of said resin coating is dipped in an amount of pure water as solvent having a mass as 10 times great as said piece of the resin material at 120° C. under 2 atom pressure for ) twenty hours, a concentration of chlorine ion in said solvent is not higher than 50 ppm.
2. A SAW device according to claim 1 , wherein, after a piece of the resin material of said resin coating is dipped in an amount of pure water as solvent having a mass as 10 times great as said piece of resin material at 120° C. under 2 atom pressure for twenty hours, a concentration of bromine ion in said solvent is not higher than 150 ppm.
3. A SAW device according to claim 1 , wherein said resin coating covers a second surface and a side of said piezoelectric substrate.
4. A SAW device according to claim 1 , further comprising a resin cover made of said resin material for covering over a periphery and said IDT electrode.
5. A SAW device according to claim 1 , wherein said IDT electrode includes:
a first layer containing aluminum on said piezoelectric substrate; and
a second layer containing at least one of Ti, Zr, Nb, Ta, W, V, and Mn over said first layer.
6. A SAW device according to claim 5 , wherein said second layer contains aluminum.
7. A SAW device according to claim 5 , wherein said IDT electrode further includes a third layer between said first and second layers, said third layer containing respective components of said first and second layers.
8. A SAW device according to claim 1 , wherein said IDT electrode includes:
a first layer containing at least one of Ti, Zr, Nb, Ta, W, V, and Mn on said piezoelectric substrate;
a second layer containing aluminum over said first layer; and
a third layer containing at least one of Ti, Zr, Nb, Ta, W, V, and Mn over said second layer.
9. A SAW device according to claim 8 , wherein said third layer contains aluminum.
10. A SAW device according to claim 8 , wherein said IDT electrode further includes:
a fourth layer between said first and second layers, said fourth layer containing respective components of said first and second layers; and
a fifth layer between said second and third layers, said fifth layer containing respective components of said second and third layers.
11. A SAW device according to claim 1 , wherein said resin material contains filler.