Thermal management in integrated circuit using phononic bandgap structure
An encapsulated integrated circuit includes an integrated circuit (IC) die. An encapsulation material encapsulates the IC die. Within the encapsulation material, a phononic bandgap structure is configured to have a phononic bandgap with a frequency range approximately equal to a range of frequencies of thermal phonons produced by the IC die when the IC die is operating.
1 . A method of forming a device, the method comprising:
attaching an integrated circuit (IC) die to a leadframe; and
covering at least parts of the IC die and the leadframe with a structure comprising a lattice of nodes in a resin material, the nodes having a different material from the resin material.
2 . The method of claim 1 , wherein covering at least parts of the IC die and the leadframe with a structure is performed by an additive manufacturing process.
3 . The method of claim 2 , wherein the additive manufacturing process includes at least one of: vat photopolymerization, powder bed fusion, binder jetting, material jetting, sheet lamination, material extrusion, or directed energy deposition.
4 . The method of claim 1 , wherein the structure includes a phononic bandgap structure, the nodes are periodically spaced, the resin material has a first acoustic impedance and the nodes have a second acoustic impedance that is different from the first acoustic impedance.
5 . The method of claim 4 , further comprising creating a thermal channel region within the phononic bandgap structure by omitting nodes within the thermal channel region.
6 . The method of claim 5 , wherein attaching an integrated circuit (IC) die to a leadframe includes attaching a first surface of the IC die on a thermal pad of the leadframe, and the thermal channel region is coupled between a second surface of the IC die opposing the first surface and the thermal pad.
7 . The method of claim 5 , wherein thermal phonons produced by a first portion of the IC die are directed via the thermal channel region to a second portion of the IC die.
8 . The method of claim 4 , wherein forming the structure includes creating a conductive layer region by omitting nodes within the conductive layer region.
9 . The method of claim 4 , wherein forming the structure comprises:
forming a first matrix of periodically spaced nodes within the resin material to create a first region having a first lattice constant; and
forming a second matrix of periodically spaced nodes within the resin material to create a second region having a second lattice constant.
10 . The method of claim 1 , wherein forming the structure comprises:
forming a first matrix of periodically spaced nodes within the resin material to create a first region having a first acoustic impedance; and
forming a second matrix of periodically spaced nodes within the resin material to create a second region a second acoustic impedance.
11 . The method of claim 1 , wherein the nodes include filler particles.
12 . The method of claim 11 , wherein the filler particles include two or more types of filler particles.
13 . The method of claim 11 , wherein the filler particles include at least one of: particles of different hardness, or particles of different sizes.
14 . The method of claim 11 , wherein the structure includes a first region having a first number of the filler particles per unit volume and a second region having a second number of the filler particles per unit volume.
15 . The method of claim 1 ,
wherein forming the structure includes exposing part of the resin material in liquid form to light.
16 . The method of claim 1 , wherein the structure includes a first phononic bandgap structure, and the method further comprises forming a second phononic bandgap structure over the first phononic bandgap structure.
17 . The method of claim 16 , wherein the resin material is a first resin material, and forming a second phononic bandgap structure over the first phononic bandgap structure includes:
positioning the IC die in the first resin material; and
exposing the first resin material to light to form the first phononic bandgap structure;
positioning the IC die covered by the first resin material in a second resin material; and
exposing the second resin material to light to form the second phononic bandgap structure.
18 . The method of claim 1 , wherein covering at least parts of the IC die and the leadframe includes:
covering at least part of the leadframe with a first layer of the resin material;
attaching the IC die on the first layer of the resin material; and
forming a second layer of the resin material around the IC die.
19 . The method of claim 18 , wherein the leadframe includes a thermal pad.
20 . The method of claim 1 , further comprising coupling bond wires between the leadframe and the IC die, and covering the bond wires with the resin material.
21 . The method of claim 1 , wherein the leadframe is part of a quad-flat no-leads package or a dual-flat no-leads package.
22 . The method of claim 1 , wherein forming the structure includes selectively polymerizing part of the resin material into the nodes.