Molding compound including a carbon nano-tube dispersion
View Patent ↗A molding compound comprising a resin, a filler, and a carbon nano-tube dispersion is disclosed. The carbon nano-tube dispersion achieves a low average agglomeration size in the molding compound thereby providing desirable electromechanical properties and laser marking compatibility. A shallow laser mark may be formed in a mold cap with a maximum depth of less than 10 microns.
1. A molding compound comprising:
a resin;
a filler; and
a carbon nano-tube dispersion having a plurality of carbon nano-tubes, the plurality of carbon nano-tubes having surfaces that are chemically modified by a functional group to chemically bridge the surfaces of the carbon nano-tubes and the resin to improve adhesion between the carbon nano-tubes and the resin and to reduce agglomeration between various ones of the plurality of carbon nano-tubes, the chemical modification including a silane coupling agent anchored at one end to surfaces of the plurality of carbon nano-tubes to result in C—O—Si covalent bonding at the surfaces of the carbon nano-tubes, an opposing end of the silane coupling agent being bonded to the functional group.
2. The molding compound of claim 1 , wherein the carbon nano-tube dispersion has an average agglomeration size less than one micron.
3. The molding compound of claim 1 , wherein the resin comprises an epoxy and the filler comprises silica.
4. The molding compound of claim 1 , wherein the filler comprises between about 60 to about 89 percent by weight of the molding compound.
5. The molding compound of claim 1 , wherein the carbon nano-tube dispersion comprises about 0.001 to about 0.05 percent by weight of the molding compound.
6. The molding compound of claim 1 , wherein the functional group is an epoxide group.
7. The molding compound of claim 1 , wherein:
the resin is about 10 to about 30 percent by weight;
the carbon nano-tube dispersion is about 0.001 to about 0.05 percent by weight; and
the filler is about 60 to about 90 percent by weight.
8. A package comprising:
a chip; and
a mold cap covering the chip, the mold cap including a resin, a filler, and a carbon nano-tube dispersion having a plurality of carbon nano-tubes, the plurality of carbon nano-tubes having surfaces that are chemically modified by a functional group to chemically bridge the surfaces of the carbon nano-tubes and the resin to improve adhesion between the carbon nano-tubes and the resin and to reduce agglomeration between various ones of the plurality of carbon nano-tubes, the chemical modification including a silane coupling agent anchored at one end to surfaces of the plurality of carbon nano-tubes to result in C—O—Si covalent bonding at the surfaces of the carbon nano-tubes, an opposing end of the silane coupling agent being bonded to the functional group.
9. The package of claim 8 , further comprising a laser mark on a surface of said mold cap.
10. The package of claim 9 , wherein said laser mark has a maximum depth less than 10 microns into said mold cap.
11. The package of claim 8 , further comprising a bonding wire connected to said chip and extending within said mold cap directly beneath said laser mark.
12. The package of claim 8 , wherein the functional group is an epoxide group.
13. The package of claim 8 , wherein the mold cap comprises:
the resin at about 10 to about 30 percent by weight;
the carbon nano-tube dispersion at about 0.001 to about 0.05 percent by weight; and
the filler at about 60 to about 90 percent by weight.
14. The molding compound of claim 1 , wherein the reduced agglomeration between various ones of the plurality of carbon nano-tubes increases electrical resistance in the compound as compared with a plurality of agglomerated carbon nano-tubes.
15. The package of claim 8 , wherein the reduced agglomeration between various ones of the plurality of carbon nano-tubes increases electrical resistance in the mold cap as compared with a plurality of agglomerated carbon nano-tubes.
16. A molding compound comprising:
a resin;
a filler; and
a carbon nano-tube dispersion having a plurality of carbon nano-tubes, the plurality of carbon nano-tubes having surfaces that are chemically modified by a functional group to chemically bridge the surfaces of the carbon nano-tubes and the resin to improve adhesion between the carbon nano-tubes and the resin and to reduce agglomeration between various ones of the plurality of carbon nano-tubes, the chemical modification including a silane coupling agent anchored at one end to surfaces of the plurality of carbon nano-tubes to result C—O—Si covalent bonding at the surfaces of the carbon nano-tubes, an opposing end of the silane coupling agent being bonded to the functional group, the plurality of carbon nano-tubes having an agglomeration size of less than one micron to increase heat absorption of the molding compound.
17. The molding compound of claim 16 , wherein the carbon nano-tube dispersion comprises about 0.001 to about 0.05 percent by weight of the molding compound.
18. The molding compound of claim 16 , wherein the plurality of carbon nano-tubes has a functional group comprising an epoxide group.
19. The molding compound of claim 16 , wherein:
the resin is about 10 to about 30 percent by weight;
the carbon nano-tube dispersion is about 0.001 to about 0.05 percent by weight; and
the filler is about 60 to about 90 percent by weight.