If you are using a self driller into aluminum or any dissimilar metal connection with a screw, make sure you use a screw that is specifically designed for dissimilar metal applications. Otherwise, you may run into HASCC (Hydrogen assisted stress corrosion cracking) which can cause the heads of the screws to pop of over time. These screws have a hardend drill tip but the shank remains ductile so that embrittlement issues don't effect it's performance. I think most mfg's have some sort of screw for this application, here is an example.
