Wire bond mold lock method and structure
View Patent ↗A method and apparatus are described for fabricating a microchip structure ( 70 ) which protects interior electrical integrated circuits and components ( 120 ) attached to a lead frame die flag ( 104 ) using a molding compound ( 124 ) that mechanically interlocks with one or more positive mold lock structures formed as dummy wire loops ( 114 ) or stud bumps ( 214 ) that are attached to the lead frame ( 100 ) and/or die flag ( 104 ).
1. A method comprising:
providing a lead frame comprising a first die paddle and one or more electrical connector elements; and
forming one or more positive mold lock structures at predetermined locations on a top surface of the lead frame which laterally protrude above the top surface.
2. The method of claim 1 , further comprising mounting a microelectronic device onto the lead frame before or after forming the one or more positive mold lock structures.
3. The method of claim 1 , further comprising forming a molded body on at least the top surface of the lead frame to encapsulate a microelectronic device attached to the lead frame and engage with the one or more positive mold lock structures to promote adhesion between the molded body and the lead frame.
4. The method of claim 1 , where forming one or more positive mold lock structures comprises using a wedge bonding process to form one or more wedge-to-wedge loops as dummy features on the lead frame.
5. The method of claim 1 , where forming one or more positive mold lock structures comprises using a wedge bonding process to form one or more wedge-to-wedge loops on the first die paddle.
6. The method of claim 1 , where forming one or more positive mold lock structures comprises using a wedge bonding process to form one or more wedge-to-wedge loops on the one or more electrical connector elements.
7. The method of claim 1 , where forming one or more positive mold lock structures comprises forming one or more wedge-to-wedge loops which are positioned as a fence around a down bond region.
8. The method of claim 1 , where forming one or more positive mold lock structures comprises using a ball bonding process to form one or more stud bumps on the first die paddle or on the one or more electrical connector elements or on a tie bar of the lead frame.
9. The method of claim 1 , where forming one or more positive mold lock structures comprises forming a stud bump by ultrasonically forming a wedge bond with an attached wire component and then breaking off the wire component directly adjacent to the wedge bond, leaving the wedge bond region as the stud bump on the first die paddle or on the one or more electrical connector elements or on a tie bar of the lead frame.