Products for Silver-Alloy layers
Corrosion problem of AgX-targets
Developments in sputtering technology have some DVD-ROM manufacturers considering using Silver-Alloy targets as a less expensive alternative to Gold for the reflective layers of DVD-9.
The inherent properties of conventional DVD adhesives currently available in the market, however, are not appropriate for use with Silver-Alloy as silver is easily corroded.
Solution
DIC has solved this problem by developing the new DVD adhesives SD-694 and SD-698. SD-694 is a newly formulated DVD adhesive designed to prevent humidity permeation. SD-698 is the increased viscosity version of this adhesive.
The result is a lower increase of PI errors after 480h chamber test.
Chamber Test
These two DVD-9 discs were made for chamber testing (temperature = 80°C, humidity = 95%).
Disc A, bonded with our SD-694, survived the chamber test. The photo was taken after 480 hours, no corrosion can be detected.
Disc B, with conventional DVD adhesive, shows signs of corrosion and migration of Ag after only 96 hours in the chamber.
Our analysis determined that humidity permeability of the adhesive layer correlates to corrosion/Ag-migration of the silver reflective layer. The SEM-Analysis shows the destructive corrosion on Disk B:
Technical Information
| SD-694 | SD-698 | |||
| before curing: | ||||
|
Viscosity: Refractive Index: |
360 mPas 1,507 |
580 mPas 1,507 |
||
| after curing: | ||||
|
Tg Modulus 30°C 50°C 75°C 100°C Shrinkage on curing |
> 150°C 2.000 MPa . . . 7,0% |
> 135°C 2.000 MPa 1.600 MPa 1.100 MPa 700 MPa 6,1% |
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