Plastic overmolded packages with mechancially decoupled lid attach attachment
View Patent ↗The specification describes a lidded MCM IC plastic overmolded package with a chimney-type heat sink. The lid is mechanically decoupled from the chimneys by a compliant conductive polymer plug.
1. Method for the manufacture of an overmolded MCM IC package comprising:
a. attaching N semiconductor IC devices to a substrate, where N is at least 2,
b. attaching N heat sinks to the IC devices, with each IC device provided with a heat sink, the heat sinks having a bottom attached to an IC device, and a top,
c. molding an overmold encapsulating the IC devices and the heat sinks, leaving the tops of the heat sinks exposed,
e. applying a plurality of N plugs of a first polymer material selectively to the exposed tops of the heat sinks,
f. applying a second polymer material to the surface of the overmold, and
g. applying a lid to the second polymer material.
2. The method of claim 1 wherein first and second polymer materials are applied, the lid is applied, and then the first and second materials are cured in the same curing step.
3. The method of claim 1 wherein the IC devices are electrically connected to the substrate with wire bonds.
4. The method of claim 1 wherein the second polymer material is applied over the overmold and over the first polymer material.
5. The method of claim 1 wherein the first polymer material has a Tg lower than the Tg of the second polymer material.
6. The method of claim 5 wherein the first polymer material has an elastic modulus lower than the elastic modulus of the second polymer material.
7. The method of claim 1 wherein the first polymer material has a conductivity greater than 0.7 W/mK.
8. The method of claim 1 wherein the second polymer material has a conductivity less than 0.3 W/mK.
9. The method of claim 1 wherein the first conductive polymer is not an adhesive polymer.