Method of forming low wire loops and wire loops formed using the method
View Patent ↗A method of bonding wire between first and second bonding points with a bonding tool, such as a capillary, is disclosed. A first bond is formed at the first bonding point with the bonding tool, and further steps include moving the bonding tool away from the first bond by a first distance, then moving the bonding tool towards the first bonding point and coupling the wire to the first bond. Thereafter, the bonding tool is moved away from the first bond by a second distance and a kink is formed in the wire. The bonding tool is subsequently moved to extend a sufficient length of wire to form a wire loop between the first and second bonding points before the bonding tool is moved to the second bonding point to form a second bond. Characteristics of wire bonds formable using the method are also disclosed.
1. A method of bonding wire between first and second bonding points with a bonding tool, comprising, in the order stated, the steps of:
forming a first bond at the first bonding point with the bonding tool;
moving the bonding tool to a first position spaced from the first bond by a first distance;
moving the bonding tool from the first position towards the first bonding point and applying a pressing force on the first bond with the wire but without forming a second bond of the wire;
moving the bonding tool to a second position spaced from the first bond by a second distance;
forming a kink in the wire;
moving the bonding tool to extend a sufficient length of wire to form a wire loop between the first and second bonding points; and
thereafter moving the bonding tool to the second bonding point and forming a second bond.
2. A method according to claim 1 , wherein:
the first position is substantially vertically above the first bonding point; and
the step of moving the bonding tool to the first position includes the steps of moving the bonding tool substantially vertically upwards and thereafter moving the bonding tool towards the second bonding point while keeping the bonding tool substantially vertically over the first bond.
3. A method according to claim 1 , wherein the step of moving the bonding tool away from the first bond to the first position includes the steps of moving the bonding tool substantially vertically upwards and thereafter moving the bonding tool away from the second bonding point.
4. A method according to claim 3 , wherein the step of moving the bonding tool away from the second bonding point comprises moving the bonding tool in a curved motion to a point outside a vertical plane passing through the first and second bonding points.
5. A method according to claim 4 , including the step of subsequently moving the bonding tool towards the first bonding point in a curved motion to a point on the vertical plane passing through the first and second bonding points before applying the force on the first bond with the wire.
6. A method according to claim 1 , wherein the step of moving the bonding tool away from the first bond to the second position comprises the step of moving the bonding tool substantially vertically upwards.
7. A method according to claim 6 , including the step of moving the bonding tool away from the second bonding point after moving the bonding tool vertically upwards.
8. A method according to claim 1 , wherein the step of forming a kink in the wire comprises the steps of moving the bonding tool from the second position to a third position in a direction away from the second bonding point, then from the third position to a fourth position still further away from the second bonding point, and then from the fourth position back to the third position.
9. A method according to claim 1 , wherein a diameter of the wire is approximately 1.0 mil or less and a height of a highest point on the bonded wire relative to the first bonding point is less than or equal to 2.35 times the diameter of the wire.