Abstract: A semiconductor device includes a first layer including a number of first layer metal pads, a second layer formed on top of the first layer, the second layer including a number of second layer metal pads, and vias connecting the first layer metal pads to the second layer metal pads. A surface area overlap between the first layer metal pads and the second layer metal pads is below a defined threshold.

Abstract: A piston plunger consists of a suction cup, a cylindrical tube and a handle. Inside the cylindrical tube is a piston. A small air hole is provided in a connector between the suction cup and the cylindrical tube through which air inside of the cup can pass. The handle has an air vent. When a clogged water pipe or the like needs to be cleaned, the suction cup is placed directly on the opening of the pipe and downward pressure is applied to the suction cup. The air compressed in the cup passes through the air hole in the connector and forces the piston up the tube until the cup is pressed down tightly against the opening. There is sufficient clearance between the piston and the tube for the piston then to drop down the tube under gravity with the trapped air being free to escape through the vent in the handle. Repeatedly downwardly pressing the plunger in this manner is effective to unclog the pipe.