US 9,287,236 B2Granted

Flexible packaged integrated circuit

AssigneeFreescale Semiconductor, Inc.

InventorsTeck Beng Lau, Chee Seng Foong, Chin Teck Siong

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Abstract

A method for assembling a thin, flexible integrated circuit (IC) device includes using an etched contoured lead frame having raised features. A die is attached to the lead frame to form a sub-assembly that is then selectively coated with a low-modulus gel. The sub-assembly is covered with a temporary mask for sputter deposition of a metallic seed layer for interconnects between the die and the raised features. The mask is removed and more robust metal interconnects are grown over the seed paths using electroplating. The sub-assembly top is then coated with another gel layer. The bottom of the sub-assembly and of the contoured lead frame is removed, which transforms the raised features into leads. The newly exposed bottom of the sub-assembly is covered with a third layer of gel to complete assembly of the packaged device.

Claims18

Dependent claims

A method assembling a packaged integrated circuit (IC) device, the method comprising:

(a) forming a sub-assembly by attaching an IC die comprising a plurality of contact points to a contoured lead frame, the lead frame comprising a base plate and a plurality of raised features;
(b) applying a first encapsulant on the top of the sub-assembly of step (a);
(c) forming conductive interconnects between the plurality of contact points and corresponding raised features of the plurality of raised features;
(d) applying a second encapsulant on top of the sub-assembly of step (c);
(e) removing the bottom of the sub-assembly of step (d), including the base plate, to separate the raised features;
and
(f) applying a third encapsulant on the bottom of the sub-assembly of step (e),
wherein the first, second and third encapsulants comprise a low-modulus gel and after curing, the low-modulus gel has a tensile modulus below 100MPa.

5 more elements

Dependencies are inferred from the claim text.