Enhanced stress metal spring contactor
View Patent ↗Several embodiments of stress metal springs are disclosed, which typically comprise a plurality of stress metal layers that are established on a substrate, which are then controllably patterned and partially released from the substrate. An effective rotation angle is typically created in the formed stress metal springs, defining a looped spring structure. The formed springs provide high pitch compliant electrical contacts for a wide variety of interconnection systems, including chip scale semiconductor packages, high density interposer connectors, and probe contactors. Several embodiments of massively parallel interface integrated circuit test assemblies are also disclosed, comprising one or more substrates having stress metal spring contacts, to establish connections between one or more separated integrated circuits on a compliant wafer carrier.
1. A contactor, comprising:
at least one stress metal spring formed on a surface of a substrate, said stress metal spring having an anchor portion attached to said substrate surface and a free portion, initially attached to said substrate surface, said stress metal spring comprising a plurality of layers, at least two of the layers having different inherent levels of stress which effect rotation of said free portion of said stress metal spring from said substrate surface by an effective rotation angle upon release of said free portion from said substrate surface; and
at least one plated metal layer substantially covering said stress metal spring.
2. The contactor of claim 1 , wherein said at least one plated metal layer comprises any of nickel, an alloy of nickel which may be selected from the group comprising nickel iron, nickel cobalt, nickel cobalt iron, nickel molly, nickel tungsten, nickel iron tungsten, nickel cobalt tungsten, nickel rhodium, nickel cobalt manganese, nickel iron rhodium, nickel iron manganese, palladium, an alloy of palladium, palladium cobalt, gold, an alloy of gold, silver, rhodium, cobalt, an alloy of cobalt, tin, an alloy of tin, copper, an alloy of copper, and lead containing or lead free solder materials.
3. The contactor of claim 1 wherein said at least one plated metal layer is applied any of before or after release of said free portion from said substrate surface.
4. The contactor of claim 1 wherein said at least one plated metal layer is applied with any of electroplating, electroless plating, sputtering and evaporation.
5. The contactor of claim 1 wherein said at least one plated metal layer provides any of increased mechanical strength, reduced electrical resistance, increased resistance to mechanical wear and reduced debris pickup.
6. The contactor of claim 1 wherein said free portion of said at least one stress metal spring extends from said anchor portion to define a tip, and
wherein said at least one plated metal layer envelopes at least a portion of said free portion of said at least one stress metal spring extending from the tip toward the anchor portion.
7. The contactor of claim 1 wherein said at least one stress metal spring provides an electrical connection to any of a printed wiring board, an integrated circuit, a chip scale package, and a solder ball.
8. The contactor of claim 1 , wherein said at least one stress metal spring comprises a plurality said stress metal springs defining an array for providing any of tight pitch, vertical compliance, and planarity compliance.
9. The contactor of claim 1 wherein said contactor comprises any of an interposer, a separable connector, and an interface assembly.
10. The contactor of claim 1 , wherein said substrate comprises any of an integrated circuit package, an integrated circuit device, and a printed circuit board.
11. An electrical connection made between a printed wiring board and a substrate comprising:
at least one electrical contact pad on the surface of said printed wiring board;
at least one stress metal spring having a contact area, said stress metal spring formed on a substrate surface having an anchor portion attached to said substrate surface and a free portion, initially attached to said substrate surface, said stress metal spring comprising a plurality of layers, at least two of the layers having different inherent levels of stress which effect rotation of said free portion of said stress metal spring from said substrate surface by an effective rotation angle upon release of said free portion from said substrate surface, and one or more plating layers substantially covering said stress metal spring; and
at least one solder ball contact between said printed wiring board contact pad and said contact area of said stress metal spring.
12. The electrical connection of claim 11 , wherein said at least one stress metal spring provides any of a permanent and a demountable connection to said solder ball.
13. The electrical connection of claim 11 , further comprising an array of said solder balls on any of an integrated circuit, an active device, a printed wiring board, and a chip scale package.
14. The electrical connection of claim 11 , wherein said plating layers substantially cover said free portion of said stress metal spring.
15. The electrical connection of claim 11 , wherein said plating layers comprise any of nickel, an alloy of nickel which may be selected from the group comprising nickel iron, nickel cobalt, nickel cobalt iron, nickel molybdenum, nickel tungsten, nickel iron tungsten, nickel cobalt tungsten, nickel rhodium, nickel cobalt manganese, nickel iron rhodium, nickel iron manganese, palladium, an alloy of palladium, palladium cobalt, gold, an alloy of gold, silver, rhodium, cobalt, an alloy of cobalt, tin, an alloy of tin, copper, an alloy of copper, and lead containing or lead free solder materials.
16. The electrical connection of claim 11 , wherein said at least one metal layer is applied before or after release of said free portion from said substrate surface.
17. The electrical connection of claim 11 , wherein said at least one metal layer is applied with any of electroplating, electroless plating, sputtering, evaporation, or equivalent processes.
18. The electrical connection of claim 11 , wherein said at least one metal layer provides any of increased mechanical strength, reduced electrical resistance, increased resistance to mechanical wear, reduced debris pickup, and increased solder connection compatibility.
19. The electrical connection of claim 11 , wherein said free portion of said at least one stress metal spring extends from said anchor portion to define a tip, and wherein said at least one metal layer envelopes at least a portion of said free portion of said at least one stress metal spring extending from the tip toward the anchor portion.
20. The electrical connection of claim 11 , wherein said at least one stress metal spring comprises a plurality of stress metal springs defining an array for providing any of tight pitch, vertical compliance, and planarity compliance.
21. The electrical connection of claim 11 , wherein said substrate comprises any of an interposer, a separable connector, and an interface assembly.
22. The electrical connection of claim 11 , wherein said substrate comprises any of an integrated circuit package substrate, an integrated circuit device, and a printed circuit board.