Off substrate kinking of bond wire
An electrically conductive lead is formed using a bonding tool. After bonding the wire to a metal surface and extending a length of the wire beyond the bonding tool, the wire is clamped. Movement of the bonding tool imparts a kink to the wire at a location where the wire is fully separated from any metal element other than the bonding tool. A forming element, e.g., an edge or a blade skirt provided at an exterior surface of the bonding tool can help kink the wire. Tensioning the wire using the bonding tool causes the wire to break and define an end. The lead then extends from the metal surface to the end.
1. A method of forming an electrically conductive lead of a component, comprising:
a) using a bonding tool to bond a wire extending beyond a surface of a bonding tool to a metal surface;
b) drawing the bonding tool away from the metal surface while allowing the wire to extend farther from the surface of the bonding tool;
c) clamping the wire to limit further extension of the wire beyond the surface of the bonding tool;
d) moving the bonding tool while the wire remains clamped such that the bonding tool imparts a kink to the wire at a location where the wire is fully separated from any metal element other than the bonding tool; and
e) tensioning the wire using the bonding tool such that the wire breaks at the kink to define an end, wherein the lead comprises the wire extending from the metal surface to the end.
2. The method as claimed in claim 1 , wherein the drawing of the bonding tool causes a predetermined length of the wire of at least 50 microns to extend between the surface of the bonding tool and the metal surface.
3. The method as claimed in claim 1 , wherein the end of the wire has a width in at least one direction which is smaller than a diameter of the wire at a location between the metal surface and the end.
4. The method as claimed in claim 1 , wherein the end of the wire has diameter in all directions which is smaller than a diameter of the wire at a location between the metal surface and the end.
5. The method as claimed in claim 1 , wherein the bonding of the metal wire comprises forming a ball bond at an end of the wire joined to the metal surface.
6. The method as claimed in claim 5 , wherein d) is performed such that the wire is moved to within 100 microns of a surface of the ball bond.
7. The method as claimed in claim 1 , wherein a forming element is provided at an exterior surface of the bonding tool, and the moving of the bonding tool imparts the kink by forcing the wire against the forming element.
8. The method as claimed in claim 1 , wherein the forming element includes an edge exposed at the exterior surface, the moving of the bonding tool imparts the kink by forcing the wire against the edge.
9. The method as claimed in claim 1 , wherein the metal surface is a surface of a metal element, wherein the method includes repeating steps a) through e) one or more times to form a plurality of leads bonded to the metal surface, then forming a dielectric element surrounding individual leads of the plurality of leads, and patterning the metal element to form a plurality of metal features at a surface of the dielectric element, each lead bonded to a feature of the plurality of features.
10. The method as claimed in claim 1 , wherein the metal surface is a surface of a metal feature of a plurality of metal features at a surface of dielectric structure of the component, and the method includes repeating steps a) through e) one or more times to form a plurality of leads bonded to metal surfaces of the metal features, then forming a dielectric element surrounding individual leads of the plurality of leads, wherein the ends of the leads are uncovered by the dielectric element at a surface of the dielectric element.
11. The method as claimed in claim 10 , wherein the forming of the dielectric element includes molding an encapsulant surrounding the individual leads of the plurality of leads.
12. The method as claimed in claim 1 , wherein the drawing of the bonding tool is performed while moving the bonding tool away from the metal surface at least partly in a first lateral direction, and then moving the bonding tool at least partly in a second lateral direction opposite the first lateral direction so as to form a first bend in the wire, the first and second lateral directions being parallel to the metal surface.
13. The method as claimed in claim 1 , wherein b) comprises drawing the bonding tool in an upward direction away from a reference plane defined by the metal surface, and d) comprises moving the bonding tool in a downward direction towards the reference plane.
14. The method as claimed in claim 1 , wherein b) comprises drawing the bonding tool in an upward direction away from a reference plane defined by the metal surface and drawing the bonding tool in a first lateral direction away from the metal surface, and then moving the bonding tool at least partly in a second lateral direction opposite the first lateral direction so as to form a first bend in the wire.
15. The method as claimed in claim 1 , wherein b) comprises drawing the bonding tool in an upward direction away from a reference plane defined by the metal surface, then drawing the bonding tool at least partly in a first lateral direction parallel to the metal surface, and then drawing the bonding tool again in an upward direction away from a reference plane defined by the metal surface, and d) comprises moving the bonding tool in a downward direction towards the reference plane.
16. A method of forming a component assembly having a plurality of electrically conductive leads, comprising:
a) using a bonding tool to bond a wire extending beyond a surface of a bonding tool to a metal feature at a surface of a component;
b) drawing the bonding tool away from the metal surface while allowing the wire to extend farther from the surface of the bonding tool;
c) clamping the wire to limit further extension of the wire beyond the surface of the bonding tool;
d) moving the bonding tool while the wire remains clamped such that the bonding tool imparts a kink to the wire at a location where the wire is fully separated from any metal element other than the bonding tool;
e) tensioning the wire using the bonding tool such that the wire breaks at the kink to define an end, wherein the lead comprises the wire extending from the metal feature to the end;
f) repeating a) through e) a plurality of times to form a plurality of the leads, wherein the end of each lead is at least 50 microns from the metal surface to which it is bonded; and
g) forming an encapsulation surrounding individual leads of the plurality of leads, wherein the ends of the leads are not fully covered by the encapsulation at a surface of the encapsulation.
17. The method as claimed in claim 16 , wherein a) is performed such that a ball bond forms where the wire is bonded to the metal surface and d) is performed such that the wire is moved to within 20 microns of a surface of the ball bond.
18. The method as claimed in claim 16 , wherein the drawing of the bonding tool is performed while moving the bonding tool away from the metal surface at least partly in a first lateral direction, and then moving the bonding tool at least partly in a second lateral direction opposite the first lateral direction so as to form a first bend in the wire, the first and second lateral directions being parallel to the metal surface.
19. The method as claimed in claim 16 , wherein b) comprises drawing the bonding tool in an upward direction away from a reference plane defined by the metal surface, and d) comprises moving the bonding tool in a downward direction towards the reference plane.
20. The method as claimed in claim 16 , wherein b) comprises drawing the bonding tool in an upward direction away from a reference plane defined by the metal surface and drawing the bonding tool in a first lateral direction away from the metal surface, and then moving the bonding tool at least partly in a second lateral direction opposite the first lateral direction so as to form a first bend in the wire.