초록 ▼

Injection or transfer molding of plastic is performed in a manner that virtually eliminates flash. Deflection of the mold press is measured with the mold press in a clamping configuration. Then the support structure of the molds is arranged to apply an equal force to the mold face by configuring sup

Injection or transfer molding of plastic is performed in a manner that virtually eliminates flash. Deflection of the mold press is measured with the mold press in a clamping configuration. Then the support structure of the molds is arranged to apply an equal force to the mold face by configuring supporting pillars and bars such that they act as individual springs. Their spring constants and/or lengths are calculated to account for the actual deflection found in the mold press, thereby, producing a uniform pressure on the molds during clamping of the press.

대표청구항 ▼

A molding apparatus for encapsulating electronic devices comprising: separable mold plates adapted to receive multiple electronic devices for encapsulation; a press having a first moveable platen and a second fixed platen, said fixed platen being held by four posts, wherein said press is adapted for

A molding apparatus for encapsulating electronic devices comprising: separable mold plates adapted to receive multiple electronic devices for encapsulation; a press having a first moveable platen and a second fixed platen, said fixed platen being held by four posts, wherein said press is adapted for clamping said mold plates together between said platens with a predetermined force; mounting blocks for attaching said mold plates to said platens; wherein said mold plates and said platens have a common centerline perpendicular to said platens; wherein said mounting blocks between said mold and at least one of said platens have different lengths as a function of their distance R from said center line; wherein the differences in lengths (H-z) of said said mounting blocks are determined according to the equations, (H-z)=(D/2)-[(D/2)2-R2]½, where D=(A2+B2)/4H, where A and B are the lateral separations between said posts, and where H is the measured deflection of the center of said at least one platen when said predetermined force is applied by said press. A method for encapsulating electronic devices comprising: providing separable mold plates having mating surfaces and adapted to receive multiple electronic devices for encapsulation; providing a press having a first moveable platen and a second fixed platen, said fixed platen being held by four posts, wherein said press is adapted for clamping said mold plates together between said platens with a predetermined force; providing mounting blocks for attaching said mold plates to said platens, wherein said mounting blocks between said mold and at least one of said platens have different lengths as a function of their distance R from the centerline of said press, wherein the differences in lengths (H-z) of said mounting blocks are determined according to the equations, (H-z)=(D/2)-[(D/2)2-R2]½, where D=(A2+B2)/4H, where A and B are the lateral separations between said posts, and where H is the measured deflection of the center of said at least one platen when said predetermined force is applied by said press; attaching said mold plates to said platens with the centerline of said mold substantially coincident with said centerline of said press and using said attachment blocks of different length; opening said press to separate said mold into two parts; placing said electronic parts to be encapsulated in a first of said mold parts; closing said mold; applying a clamping force to said mold in said press to seal the mating surfaces of said mold parts; providing a plastic encapsulant material to a reservoir in said mold; injecting said plastic encapsulant into said mold cavities surrounding said electronic parts to encapsulate them; thereafter opening said mold and removing said encapsulated parts.