Composition monitoring for one year of lube cross-contamination of hard disks using aluminum substrates

The possibility of chemical reactions between different lubes for hard disks is a concern that should be investigated to ensure a high level of quality for hard disk drives when the same assembly process is used for different drives. To investigate cross-contamination by different disk lubes, a novel characterization method was developed, using an aluminum disk substrate with an Ni-P underlayer as a witness disk, instead of the silicon wafers currently used. One-year monitoring of organic and ionic materials in a clean room for manufacturing lines showed that the method had good detection ability and operability. It was also confirmed that lube cross-contamination was below the level at which it could cause chemical reactions between lubes.