Patent ID: 7380440

Claim:
A method for manufacturing unleaky closed containers having a wall with a flexible wall area and an opening in said wall, said opening being closed by a foil-like member bonded to a rim of said opening, wherein said foil-like member bows out by a bow-out distance when the interior of said container is pressurized, comprising providing a closed container; depositing said closed container opposite said foil-like member on a support; providing a stationary force detector adjacent to said foil-like member at a distance which is smaller than said bow-out distance or in contact with said foil-like member, said force detector generating an output signal; biasing said flexible wall area toward the interior of said container, thereby pressurizing said container; sampling a first force indicative signal dependent from said output signal at a first point in time; sampling a second force indicative signal dependent from said output signal at a second, subsequent point in time; generating a difference signal from said first and second force indicative signals as a leak indicative signal and considering said container as unleaky, if said difference signal fulfils a test criterion.