Method of forming low profile wire bonds between integrated circuits dies and printed circuit boards

1. A method of profiling a series of wire bonds between a line of contact pads on a die, and a corresponding set of conductors on a supporting structure, the method comprising the steps of:

electrically connecting each of the contact pads on the die to a corresponding conductor on the supporting structure with a respective wire bond, each of the wire bonds extending in an arc from the contact pad to the conductor; and,

pushing on each of the wire bonds individually to collapse the arc and plastically deform the wire bond such that the plastic deformation maintains the wire bond in a flatter profile shape; wherein,

the step of forming the line of wire bonds uses a wirebonder that has a bonding tool for moving between the contact pads and their respective corresponding conductors, and the line of wire bonds are sequentially pushed by a wire engaging structure on the wirebonder, the wire engaging structure and the bonding tool being configured for synchronized movement such that the wire engaging structure pushes the wire bond immediately adjacent the wire bond currently being formed by the bonding tool.

2. A method according to claim 1 wherein the wirebonder is a wedge type wirebonder and the bonding tool is a wedge such that during use, the wedge holds a piece of wire in contact with one of the contact pads on the die to form a weld connection before moving to the corresponding conductor on the PCB to weld the other end of the wire and formal wire bond, and the wire engaging structure has a wire pushing surface that contacts the wire bond, the wire pushing surface is adjacent to, and 1.0 mm to 1.6 mm behind the wedge with respect to the movement of the wedge towards the IC die.

3. A method according to claim 2 wherein the wire pushing surface is between 50 microns to 400 microns closer to the PCB than the wedge.

4. A method according to claim 1 wherein the line of wire bonds does not extend more than 150 microns above the contact pads of the IC die.

5. A method according to claim 4 wherein the line of wire bonds does not extend more than 50 microns above the contact pads of the IC die.

6. A method according to claim 1 wherein the wire bonds are attached to the contact pads with a bond strength greater than 3 g force.

7. A method according to claim 1 wherein the contact pads are spaced from the corresponding conductors on the PCB by more than 1 mm.

8. A method according to claim 7 wherein the contact pads are between 2 mm and 3 mm from the corresponding conductors on the PCB.

9. A method according to claim 1 wherein the PCB is a flexible PCB mounted to a support structure together with the die such that the conductors are adjacent the contact pads on the die.

10. A method according to claim 9 wherein the support structure has a chip mounting area for supporting the die, the die having a back surface in contact with the chip mounting area and an active surface opposing the back surface, the active surface having the contact pads, and the chip mounting area being raised relative to the remainder of the support structure such that the contact pads are raised relative to the conductors.

11. A method according to claim 10 wherein the support structure is a liquid crystal polymer (LCP) molding.

12. A method according to claim 10 wherein the active surface has functional elements spaced less than 260 microns from the contacts pads of the die.

13. A method according to claim 12 wherein the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected.

14. A method according to claim 11 wherein the wire bonds are covered in a bead of encapsulant, the bead of encapsulant extending less than 200 microns above the active surface of the die.

15. A method according to claim 14 wherein the wire bonds are covered in a bead of encapsulant, the bead of encapsulant having a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.

16. A method according to claim 13 wherein the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.