Semiconductor leadframes having dual surface finish for varied molding compound adhesion
First Claim
1. A leadframe strip for use in the assembly and packaging of integrated circuit devices, said strip made from a sheet of base metal and said packaging including encapsulation material, comprising:
- a series of leadframe units formed in said base metal and arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails, wherein said rails are positioned along the outer edges of said strip, thus holding said strip together;
a surface configuration of said base metal for said leadframe units such that said surface maximizes adhesion to said encapsulation material; and
a surface configuration of said base metal for said rails such that said surface minimizes adhesion to said encapsulation material.
1 Assignment
0 Petitions
Accused Products
Abstract
A leadframe strip for use in the assembly of integrated circuit devices, which is made from a sheet of base metal and comprises a series of leadframe units formed in this base metal. The units are arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails. The rails are positioned along the outer edges of the strip, thus holding the strip together. The strip has a surface configuration for the leadframe units such that the surface maximizes adhesion to the encapsulation material. The strip further has a surface configuration for the rails such that the surface minimizes adhesion to the encapsulation material.
-
Citations
19 Claims
-
1. A leadframe strip for use in the assembly and packaging of integrated circuit devices, said strip made from a sheet of base metal and said packaging including encapsulation material, comprising:
-
a series of leadframe units formed in said base metal and arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails, wherein said rails are positioned along the outer edges of said strip, thus holding said strip together;
a surface configuration of said base metal for said leadframe units such that said surface maximizes adhesion to said encapsulation material; and
a surface configuration of said base metal for said rails such that said surface minimizes adhesion to said encapsulation material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A leadframe strip for use in the assembly of integrated circuit devices, said strip made from a sheet of base metal, comprising:
-
a series of leadframe units formed in said base metal and arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails, wherein said rails are positioned along the outer edges of said strip, thus holding said strip together;
said strip having an adherent first layer comprising nickel on said base metal; and
an adherent second layer of metal on said nickel layer, wherein said second metal is selected for improved adherence to encapsulation compounds and bonding wires;
said second layer selectively placed on said units, leaving said rails uncovered.
-
-
12. A method for fabricating a leadframe strip for use in the assembly and packaging of integrated circuit devices, comprising the steps of:
-
forming a plurality of leadframe units from a sheet of base metal, each of said units comprising a mount pad for an integrated circuit chip and a plurality of lead segments, said series of units arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails, wherein said rails are positioned along the outer edges of said strip and are holding said strip together;
selectively masking said rails, thereby leaving said leadframe units exposed;
plating a layer of a metal selected for improved adherence to encapsulation compounds and bonding wires; and
removing said selective mask from said rails. - View Dependent Claims (13, 14, 15)
-
-
16. A method for fabricating a semiconductor device using
a transfer molding encapsulation process, comprising: -
providing a plurality of integrated circuit chips;
providing a leadframe strip having a series of leadframe units arranged in linear progression so that each unit is interconnected with its adjacent neighbors by supporting rails, wherein said rails are positioned along the outer edges of said strip, thus holding said strip together;
said strip having a metal-containing layer selected for improved adherence to encapsulation compounds and bonding wires, selectively placed on said units so that said rails remain uncovered;
attaching one of said chips at a time to its respective leadframe unit;
wire bonding each of said chips to their respective electrical leadframe connections, completing the assembly of said chips;
placing said strip into the cavity of a mold, closing said mold and pressuring molding compound through runners and a gate into said cavity for encapsulating said assembled chips, whereby said compound in said runners, in order to reach said gates into said cavity, crosses said rails without adhering to said rails;
opening said mold for unloading said strip, thereby separating said rails from said compound remaining in said runners. - View Dependent Claims (17, 18, 19)
-
Specification