High bond line thickness for semiconductor devices
Die attach methods used in making semiconductor devices and the semiconductor devices resulting from those methods are described. The methods include providing a leadframe with a die attach pad, using a boundary feature(s) containing a bond wire to define a perimeter on the die attach pad, depositing a conductive material (such as solder) within the perimeter, and then attaching a die containing an integrated circuit device to the die attach pad by using the conductive material. The boundary feature(s) allow an increased thickness of conductive material to be used, resulting in increased bond line thickness and increasing the durability and performance of the resulting semiconductor package. Other embodiments are described.
1. A semiconductor device, the comprising:
a leadframe containing a die attach pad;
a conductive layer on a portion of the die attach pad, wherein the conductive layer has a thickness ranging up to about 30 mil;
a boundary feature comprising a bond wire partially surrounding and contacting the conductive layer, wherein both ends of the bond wires are attached to the die attach pad; and
a die on the conductive layer.
2. The device of claim 1 , wherein the boundary feature completely surrounds the conductive layer.
3. The device of claim 1 , wherein the boundary feature surrounds at least half of the conductive layer.
4. The device of claim 1 , wherein the conductive layer has a thickness ranging from about 4 mil to about 30 mil.
5. The device of claim 1 , wherein the conductive layer is substantially free of voids between the die and the die attach pad.
6. The device of claim 1 , wherein both ends of the bond wire have been attached to the die attach pad using a wedge or stitch bond.
7. The device of claim 6 , wherein the bond wire has been attached to the die attach pad at more than two locations.
8. The device of claim 1 , wherein four bond wires are used to make the boundary feature and both ends of each bond wire are attached to the die attach pad.