Slot transfer molding apparatus and methods

A transfer mold for forming plastic parts, comprising:

• a first mold portion having a plurality of independent first half-mold cavities arranged substantially in at least one row;
• a second mold portion moveably coupled to said first mold portion, and having a plurality of independent second half-mold cavities adapted to mate with said first half-mold cavities, wherein said first and second half-mold cavities, when combined, define at least one row of mold cavities, and wherein each said mold cavity has a predetermined shape and volume;
• a plurality of slot-shaped reservoirs for plastic penetrating one of said first and second mold portions and aligned substantially parallel with and adjacent to said row of mold cavities;
• a plurality of short channels each of a predetermined shape and volume, at least one channel per mold cavity, connecting each said mold cavity to one of said slot-shaped reservoirs;
• a plurality of blades, at least one per slot-shaped reservoir, adapted to moveably engage said slot-shaped reservoirs, and of a size so as to be able to substantially fill said slot-shaped reservoirs when engaged.

A process for encapsulating objects comprising:

• providing a mold having therein a plurality of mold cavities arranged in a row and adapted to contain said objects, and further having a slot-shaped encapsulant reservoir parallel with and adjacent to said row of mold cavities and coupled to said mold cavities by short channels;
• then in arbitrary order, placing said objects in said mold cavities and placing said encapsulant in said slot-shaped encapsulant reservoir;
• thereafter advancing a blade shaped ram in said slot-shaped reservoir to compress, liquify and transfer said encapsulant from said slot-shaped reservoir into said short channels;
• and
• injecting said encapsulant from said short channels into all said mold cavity spaces at substantially the same time.

A process for encapsulating electronic components, comprising:

• loading a plurality of components into at least two rows of mold cavities mirror symmetrically disposed on each side of a slot penetrating a portion of said mold and communicating with said mold cavities by channels;
• inserting a predetermined quantity of plastic encapsulant material into said slot;
• and
• displacing, by means of at least one blade inserted in said slot, said plastic encapsulant material to arrive substantially simultaneously in said mold cavities.

A process for encapsulating electronic components in a mold without moveable gates, comprising:

• placing a plurality of components in mirror symmetric rows of mold cavities located on each side of a slot penetrating a portion of said mold and communicating with said mold cavities by substantially equal length channels;
• inserting a predetermined quantity of plastic encapsulating material into said slot;
• inserting a blade into said slot to displace said plastic, and
• injecting said plastic substantially simultaneously into all said mold cavities.

A process for forming plastic objects of a predetermined shape comprising:

• providing a separable transfer mold having cavities therein corresponding substantially to said predetermined shape and symmetrically disposed parallel with and adjacent to a slot-shaped plastic reservoir and connected thereto by short channels;
• inserting a predetermined quantity of plastic material suitable for transfer molding into said slot;
• liquifying by means of at least one blade shaped ram inserted in said slot, said plastic material;
• controlling the flow of said liquified plastic material through said channels so that said plastic material arrives substantially simultaneously in said mold cavities.

An assembly and molding line for mounting and encapsulating electronic components on a lead frame, characterized by:

• bonding means for attaching said electronic components to a first portion of said lead frame;
• molding means for encapsulating said attached electronic components comprising separable mold portions having therein a plurality of mold cavities adapted to contain said attached electronic components, arranged in at least one row, and a slot-shaped reservoir for receiving encapsulant, formed in one of said separable mold portions, and aligned parallel with and adjacent to said at least one row, and channels, at least one per cavity, connecting said cavities to said adjacent slot-shaped reservoir, and a blade shaped ram of dimensions to closely fit and moveably engage said slot-shaped reservoir and adapted to compress said encapsulant within said reservoir and inject it into said cavities via said channels;
• detaching means for separating said encapsulated electronic components from a second portion of said lead frame;
• and
• advancing means for moving said lead frame successively through said bonding means and molding means, and into said detaching means.