Reliability Metal Traces

• US 20090266621A1
• Filed: 04/25/2008
• Published: 10/29/2009
• Est. Priority Date: 04/25/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhong, John Z., Hotelling, Steve Porter, HUANG, Lili
• Granted Patent: US 8,970,504 B2
• Time in Patent Office: Days
• US Class Current: 178/18.10
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

The formation of improved reliability conductive traces in touch sensor panels that are less prone to failures due to environmental effects is disclosed. Conductive traces, which can be formed from a stackup of metal layers or a single metal layer, can be protected with an additional photoimageable passivation layer of a material such as an organic polymer. This photoimageable coating can be patterned so that it does not appear in the visible area of the touch sensor panel, with much finer tolerances than conventional passivation layers to help keep product dimensions to a minimum.

Claims

1. A method for improving reliability of conductive traces on a touch sensor panel, comprising:

forming a first layer of a first conductive material on a substrate;

forming a second layer of a second conductive material on the first layer, the first layer for adhering the second layer to the substrate;

forming a third layer of the first conductive material on the second layer, the third layer for protecting the second layer;

patterning the first, second and third layers to form the conductive traces;

applying an organic polymer photoimageable passivation layer over the conductive traces; and

using photolithography to pattern and limit the organic photoimageable passivation layer to nontransparent areas of the touch sensor panel.

2. The method of claim 1, further comprising applying a first passivation layer prior to applying the organic polymer photoimageable passivation layer, the first passivation layer formed between the conductive traces and the organic polymer photoimageable passivation layer.

3. The method of claim 1, further comprising forming the first, second and third layers from a stackup of Aluminum Neodymium (Al/Nd) sandwiched between two layers of Molybdenum Niobium (Mo/Nb).

4. The method of claim 2, further comprising forming the first passivation layer from silicon dioxide (SiO₂).

5. The method of claim 1, further comprising patterning the first, second and third layers using photolithographic techniques having tolerances of less than +/−

10 microns to minimize an overall size of the touch sensor panel.

6. A method for improving reliability of conductive traces on a touch sensor panel, comprising:

forming and patterning a Molybdenum Niobium (Mo/Nb) layer on a substrate to form the conductive traces with controlled wall angles;

applying an organic polymer photoimageable passivation layer over the conductive traces; and

using photolithography to pattern and limit the organic photoimageable passivation layer to nontransparent areas of the touch sensor panel.

7. The method of claim 6, further comprising applying a first passivation layer prior to applying the organic photoimageable passivation layer, the first passivation layer formed between the conductive traces and the organic photoimageable passivation layer.

8. The method of claim 7, further comprising applying a conductive layer between the conductive traces and the first passivation layer.

9. The method of claim 8, further comprising forming the conductive layer from Indium Tin Oxide (ITO).

10. The method of claim 7, further comprising forming the first passivation layer from silicon dioxide (SiO₂).

11. The method of claim 6, further comprising patterning the organic photoimageable passivation layer using photolithographic techniques having tolerances of less than +/−

10 microns to minimize an overall size of the touch sensor panel.

12. Improved reliability conductive traces for carrying signals on a touch sensor panel, comprising:

a first layer of a first conductive material formed on a substrate;

a second layer of a second conductive material formed on the first layer, the first layer for adhering the second layer to the substrate;

a third layer of the first conductive material formed on the second layer, the third layer for protecting the second layer; and

an organic polymer photoimageable passivation layer formed on the third layer;

wherein the first, second and third layers are patterned to form the conductive traces; and

wherein the organic photoimageable passivation layer is patterned using photolithography and limited to nontransparent areas of the touch sensor panel.

13. The improved reliability conductive traces of claim 12, further comprising a first passivation layer formed between the third layer and the organic polymer photoimageable passivation layer.

14. The improved reliability conductive traces of claim 12, the first, second and third layers comprising a stackup of Aluminum Neodymium (Al/Nd) sandwiched between two layers of Molybdenum Niobium (Mo/Nb).

15. The improved reliability conductive traces of claim 13, the first passivation layer comprising silicon dioxide (SiO₂).

16. The improved reliability conductive traces of claim 12, the first, second and third layers patterned using photolithographic techniques having tolerances of less than +/−

10 microns to minimize an overall size of the touch sensor panel.

17. The improved reliability conductive traces of claim 12, the improved reliability conductive traces formed within a touch sensor panel.

18. The improved reliability conductive trace of claim 17, the touch sensor panel incorporated within a computing system.

19. Improved reliability conductive traces for carrying signals on a touch sensor panel, comprising:

a Molybdenum Niobium (Mo/Nb) layer formed and patterned on a substrate to form the conductive traces with controlled wall angles; and

an organic polymer photoimageable passivation layer formed over the conductive traces;

wherein the organic photoimageable passivation layer is patterned using photolithography and limited to nontransparent areas of the touch sensor panel.

20. The improved reliability conductive traces of claim 19, further comprising a first passivation layer formed between the Mo/Nb layer and the organic photoimageable passivation layer.

21. The improved reliability conductive traces of claim 20, further comprising a conductive layer formed between the Mo/Nb layer and the first passivation layer.

22. The improved reliability conductive traces of claim 21, the conductive layer comprising Indium Tin Oxide (ITO).

23. The improved reliability conductive traces of claim 20, the first passivation layer comprising silicon dioxide (SiO₂).

24. The improved reliability conductive traces of claim 19, the organic photoimageable passivation layer patterned using photolithographic techniques having tolerances of less than +/−

10 microns to minimize an overall size of the touch sensor panel.

25. The improved reliability conductive traces of claim 19, the improved reliability conductive traces formed within a touch sensor panel.

26. The improved reliability conductive traces of claim 25, the touch sensor panel incorporated within a computing system.

27. Improved reliability conductive traces for carrying signals on a touch sensor panel, comprising:

a first layer of a first conductive material formed on a substrate;

a second layer of a second conductive material formed on the first layer, the first and second layers configured as transparent conductive electrodes and border electrical connections; and

an organic polymer photoimageable passivation layer formed over the first and second layers;

wherein the organic photoimageable passivation layer is patterned using photolithography and limited to nontransparent areas of the touch sensor panel.

28. The improved reliability conductive traces of claim 27, the first layer formed from Indium Tin Oxide (ITO) and the second layer formed from metal.

29. The improved reliability conductive traces of claim 27, the first layer formed from metal and the second layer formed from Indium Tin Oxide (ITO).

30. The improved reliability conductive traces of claim 27, further comprising a first passivation layer formed between the second layer and the organic photoimageable passivation layer.

31. The improved reliability conductive traces of claim 30, the first passivation layer comprising silicon dioxide (SiO₂).

32. The improved reliability conductive traces of claim 27, the organic photoimageable passivation layer patterned using photolithographic techniques having tolerances of less than +/−

10 microns to minimize an overall size of the touch sensor panel.

33. A mobile telephone including a touch sensor panel containing a plurality of improved reliability conductive traces, the improved reliability conductive traces comprising:

a first layer of a first conductive material formed on a substrate;

a second layer of a second conductive material formed on the first layer, the first layer for adhering the second layer to the substrate;

a third layer of the first conductive material formed on the second layer, the third layer for protecting the second layer; and

an organic polymer photoimageable passivation layer formed on the third layer;

wherein the first, second and third layers are patterned to form the conductive traces; and

wherein the organic photoimageable passivation layer is patterned using photolithography and limited to nontransparent areas of the touch sensor panel.

34. A digital media player including a touch sensor panel containing a plurality of improved reliability conductive traces, the improved reliability conductive traces comprising:

a Molybdenum Niobium (Mo/Nb) layer formed and patterned on a substrate to form the conductive traces with controlled wall angles; and

an organic polymer photoimageable passivation layer formed over the conductive traces;

wherein the organic photoimageable passivation layer is patterned using photolithography and limited to nontransparent areas of the touch sensor panel.