Mold clamping device with improved clamping force transmission mechanism

A mold clamping device for sealing a semiconductor element with a resin, comprising:

• a support base;
• a middle platen fixedly support by said support base;
• a lower metallic mold fixedly secured upon an upper surface of said middle platen;
• a plurality of tie-bars vertically extending through and slidably supported by said middle platen;
• a movable platen fixedly secured to top end portions of said tie-bars;
• an upper metallic mold fixedly secured upon a lower surface of said movable platen to oppose said lower metallic mold, said lower metallic mold and said upper metallic mold defining a cavity for accommodating a semiconductor element during a resin molding and sealing process;
• a horizontal connecting bar member connecting lower ends of at least two of said tie-bars;
• a quadrilateral linkage mechanism having a form of a collapsible rhombus lying on a vertical plane;
• a first and second annular link rotatably coupled to said quadrilateral linkage mechanism, respectively, said first and second annular links each having an inner thread formed on an inner surface thereof;
• a rod-shaped threaded member having a left-handed first thread and a right-handed second thread formed at an outer side surface thereof, said first and second threads engaging with said inner thread of said first and said second annular links, respectively, whereby rotation of said rod-shaped threaded member is a first direction drives said annular links toward each other upon said rod-shaped threaded member, and rotation of said rod-shaped threaded member in a second direction opposite to said first direction drives said annular links away from each other upon said rod-shaped threaded member;
• a driving means for driving said rod-shaped threaded member selectively in said first and said second directions, thereby lowering said upper metallic mold toward said lower metallic mold and raising said upper metallic mold away from said lower metallic mold, respectively, a driving force being transmitted from said driving means to said upper metallic mold through said rod-shaped threaded member, said annular links, said quadrilateral linkage mechanism, said horizontal connecting bar member, said tie-bars, and said movable platen;
• and
• means for adjusting the tilt of said movable platen, comprising:
• a first and second tie-bar fixing nut engaging with an upper end portion of a first and a second of said tie-bars, respectively, and supporting different regions of said movable platen at respective vertical levels, wherein said respective vertical levels of said movable platen regions are adjusted by turning said tie-bar fixing nuts;
• a first and second pulley fixedly secured to said first and said second tie-bar fixing nuts, respectively;
• and
• a timing belt spanning said first and second pulleys, such that said first and said second pulleys are turned together by means of said timing belt to adjust a tilting of said movable platen thereby adjusting a mold face bearing between said lower metallic mold and said upper metallic mold.