1 IntroductionrnMEMS technology is facing new challengessince thin wafer handling will be used more andmore to archive smaller dies.Packaging the next device on the top of the first and so on called packageon package (POP), first to reduce the wire bondingas the connections will be via through vias that runthrough the bulk silicon and second the size of thesecond (third, fourth…)can have the same size ofthe first one.All that means more space for the Diebut less additional work to connect the Dies to eachother.Perhaps the most significant is the substantially larger market size and the drive toward lowercosts.