US 6,943,061 B1Granted

Method of fabricating semiconductor chip package using screen printing of epoxy on wafer

AssigneeNS Electronics Bangkok (1993) Ltd.

InventorsSaravuth Sirinorakul, Thada Suriyanun

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Abstract

A layer of nonconductive epoxy is applied to a semiconductor wafer by a screen-printing process before the wafer is separated into individual dice or chips. The epoxy layer is applied as a number of sublayers. Each of the sublayers is cured, except for the final sublayer, which is partially cured. After the epoxy layer has been applied to the wafer, the wafer is separated into individual dice. Each of the dice is then attached to a die pad, a plurality of leads, or another die, using the preformed epoxy layer, by pressing the die against the die pad, leads or die at a selected force and temperature. Applying the epoxy layer to the wafer in the manner described, before dicing, allows it to be made significantly thicker than a conventionally formed epoxy layer. This prevents a leakage current between the die and another element on which the die is mounted.

Claims17

Dependent claims

A method of fabricating a semiconductor chip package comprising:

providing a semiconductor wafer, said semiconductor wafer having a top surface and a bottom surface, a plurality of bonding pads being located on said top surface;
applying at least one nonconductive epoxy sublayer to a said bottom surface of said semiconductor wafer using a screen printing process;
completely curing said at least one nonconductive epoxy sublayer;
applying a final nonconductive epoxy sublayer on top of said at least one epoxy sublayer, said at least one nonconductive epoxy sublayer and said final nonconductive epoxy sublayer together forming a nonconductive epoxy layer;
partially curing said final nonconductive epoxy sublayer such that said final epoxy sublayer is in a soft but solid form;
while said final nonconductive epoxy sublayer is still only partially cured, sawing said wafer to create a plurality of semiconductor dice, said nonconductive epoxy layer completely covering a bottom surface of each of said semiconductor dice;
and
attaching at least one of said semiconductor dice to a die-attach member by means of said nonconductive epoxy layer.

5 more elements

Dependencies are inferred from the claim text.