Methods of fabricating substrates with thermal vias and sinter-bonded thermal dissipation structures
A substrate is described with a thermal dissipation structure sintered to thermal vias. In one example, a microelectronic module includes a recess between first and second substrate surfaces. One or more thermal vias extend between the first substrate surface and the interior recess surface, wherein each of the thermal vias has an interior end exposed at the interior recess surface. A sintered metal layer is in the recess and in physical contact with the interior end of the thermal vias and a thermal dissipation structure is in the recess over the sintered metal layer. The thermal dissipation structure is attached to the substrate within the recess by the sintered metal layer, and the thermal dissipation structure is thermally coupled to the thermal vias through the sintered metal layer.
1 . A method comprising:
forming a recess in a substrate over a plurality of thermal vias within the substrate;
applying a sinter precursor material in the recess and in the thermal vias;
placing a thermal dissipation structure into the recess over the sinter precursor material; and
performing a sintering process to couple the thermal dissipation structure to the substrate.
2 . The method of claim 1 , wherein forming the recess comprises etching the substrate.
3 . The method of claim 1 , wherein forming the recess comprises sawing the substrate.
4 . The method of claim 1 , wherein placing the thermal dissipation structure comprises applying metal layers sequentially to the sinter precursor material in the recess to form the thermal dissipation structure in place in the recess.
5 . The method of claim 1 , wherein the thermal dissipation structure comprises a prefabricated solid body having a thermal conductivity that is greater than that of the substrate.
6 . The method of claim 1 , wherein applying the sinter precursor material comprises screen printing the sinter precursor material.
7 . The method of claim 1 , wherein performing the sintering process comprises baking the substrate and thermal dissipation structure in a reflow oven.
8 . The method of claim 7 , further comprising:
applying a die attach material to the thermal dissipation structure; and
applying a die to the die attach material, and
wherein performing the sintering process comprises sintering the thermal dissipation structure and sintering the die attach material at the same time.
9 . The method of claim 1 , wherein the thermal vias comprise a plurality of vertical structures interconnected with a plurality of horizontal conductive layers.
10 . The method of claim 1 , wherein the thermal dissipation structure comprises at least one of copper (Cu), aluminum (Al), and an alloy.
11 . The method of claim 1 , wherein:
the sinter precursor material comprises a paste with metal particles of at least one of gold (Au), silver (Ag), and copper (Cu); and
performing the sintering process results in formation of a sintered metal layer that couples the thermal dissipation structure to the substrate.
12 . A method of forming a microelectronic module, the method comprising:
providing a substrate having a first substrate surface, a second substrate surface, and one or more thermal vias extending into the substrate from the first substrate surface, wherein each of the thermal vias includes a first end that is co-planar with and open at the first substrate surface;
forming a recess in the second substrate surface, wherein the recess is partially defined by an interior recess surface that is between the first and the second substrate surfaces, and the one or more thermal vias extend between the first substrate surface and the interior recess surface, wherein each of the thermal vias further includes an interior end that is open and exposed at the interior recess surface;
applying a sinter precursor material in the recess and in the thermal vias;
placing a thermal dissipation structure into the recess over the sinter precursor material; and
performing a sintering process to form a sintered metal layer in the recess and in physical contact with the interior end of the thermal vias, and to form a sintered via filling that fills the thermal vias, wherein the thermal dissipation structure is attached to the substrate within the recess by the sintered metal layer, and the thermal dissipation structure is thermally coupled to the sintered via filling within the thermal vias through the sintered metal layer.
13 . The method of claim 12 , wherein the substrate includes one or more dielectric layers and one or more conductive layers.
14 . The method of claim 12 , further comprising plating interior sidewalls of at least some of the thermal vias with a conductive layer.
15 . The method of claim 12 , wherein the thermal vias comprise a plurality of vertical structures interconnected with a plurality of horizontal conductive layers.
16 . The method of claim 12 , wherein the thermal vias are configured as at least one of circular, rectangular and bar shapes.
17 . The method of claim 12 , wherein the thermal dissipation structure comprises at least one of copper (Cu), aluminum (Al), and an alloy.
18 . The method of claim 12 , wherein the thermal dissipation structure comprises a prefabricated solid body having a thermal conductivity that is greater than that of the substrate.
19 . The method of claim 12 , wherein the sintered metal layer and the sintered via filling are formed from a sinter precursor material of a paste with metal particles of at least one of gold (Au), silver (Ag), and copper (Cu).
20 . The method of claim 12 , further comprising:
coupling a die pad to the thermal vias on the substrate opposite the thermal dissipation structure; and
attaching a die to the die pad.