Power MOSFET having selectively silvered pads for clip and bond wire attach
View Patent ↗A packaged power field effect transistor device includes a power field effect transistor die, a DBA substrate, a clip, a wire bond, leads, and an amount of plastic encapsulant. The top of the DBA has a plurality of metal plate islands. A sintered silver feature is disposed on one of the islands. A silvered backside of the die is directly bonded to the sintered silver structure of the DBA. The upper surface of the die includes a first aluminum pad (a source pad) and a second aluminum pad (a gate pad). A sintered silver structure is disposed on the first aluminum pad, but there is no sintered silver structure disposed on the second aluminum pad. A high current clip is attached via soft solder to the sintered silver structure on the first aluminum pad (the source pad). A bond wire is ultrasonically welded to the second aluminum pad (gate pad).
1. An assembly comprising:
a semiconductor die having a first aluminum pad and a second aluminum pad, wherein a sintered silver structure is disposed on the first aluminum pad but wherein there is no sintered silver structure disposed on the second aluminum pad;
a clip that is attached to the sintered silver structure; and
a bond wire that is bonded to the second aluminum pad.
2. The assembly of claim 1 , further comprising:
a direct bonded aluminum (DBA) substrate that comprises a ceramic substrate member and a plate of aluminum that is direct bonded to the ceramic substrate member; and
a sintered silver structure that is disposed on the plate of aluminum, wherein the semiconductor die has a layer of silver disposed on a backside of the semiconductor die, and wherein the layer of silver on the backside of the semiconductor die is direct silver-to-silver bonded to the sintered silver structure on the plate of aluminum.
3. The assembly of claim 2 , wherein the DBA further comprises a second plate of aluminum, wherein a first end of the clip is bonded to the second plate of aluminum of the DBA, and wherein a second end of the clip is bonded to the sintered silver structure on the first aluminum pad.
4. The assembly of claim 2 , wherein the semiconductor die is a power field effect transistor device, wherein the first aluminum pad is a source pad, and wherein the second aluminum pad is a gate pad.
5. The assembly of claim 1 , wherein the clip is attached with soft solder to the sintered silver structure on the first aluminum pad.
6. The assembly of claim 2 , wherein the layer of silver is direct silver-to-silver bonded to the sintered silver structure without using any solder.
7. The assembly of claim 1 , wherein there is no non-aluminum metal layer disposed between the first aluminum pad and the sintered silver structure.
8. An assembly comprising:
a semiconductor die having a source electrode pad and a gate electrode pad, wherein a sintered silver structure is disposed on the source electrode pad but wherein there is no sintered silver structure disposed on the gate electrode pad;
a clip that is attached to the sintered silver structure; and
a bond wire that is bonded to the gate electrode pad.
9. The assembly of claim 8 , wherein the source electrode pad and the gate electrode pad are part of a power field effect transistor device.
10. The assembly of claim 8 , further comprising:
a direct bonded aluminum (DBA) substrate that comprises a ceramic substrate member and a plate of aluminum that is direct bonded to the ceramic substrate member; and
a sintered silver structure that is disposed on the plate of aluminum, wherein the semiconductor die has a layer of silver disposed on a backside of the semiconductor die, and wherein the layer of silver on the backside of the semiconductor die is direct silver-to-silver bonded to the sintered silver structure on the plate of aluminum.
11. The assembly of claim 8 , further comprising:
a direct bonded aluminum (DBA) substrate that is attached to a back-side of the semiconductor die with a solderless silver-to-silver bond.
12. The assembly of claim 8 , wherein the clip is attached with soft solder to the sintered silver structure.
13. The assembly of claim 8 , wherein there is no non-aluminum metal layer disposed between the source electrode pad and the sintered silver structure.