Method of providing printhead assembly having complementary hydrophilic and hydrophobic surfaces

1. A method of providing a printhead assembly having a hydrophilic ink pathway and a hydrophobic ink ejection face, the method comprising the steps of:

providing a printhead assembly having an inkjet printhead attached to an ink supply manifold, the inkjet printhead comprising a nozzle plate having a hydrophobic coating and a protective metal film disposed on the hydrophobic coating;

treating surfaces of an ink pathway in the printhead assembly with a solution comprising an alkoxylated polyethyleneimine;

drying the surfaces; and

removing the protective metal film so as to reveal the hydrophobic coating, thereby providing the printhead assembly having the hydrophilic ink pathway and the hydrophobic ink ejection face,

wherein said method further comprises the step of:

plasma activating the surfaces of the ink pathway before treating the surfaces with the solution comprising the alkoxylated polyethyleneimine.

2. The method of claim 1 , wherein the protective metal film is an aluminium film.

3. The method of claim 1 , wherein the hydrophobic coating comprises a polymerized siloxane.

4. The method of claim 1 , wherein the surfaces are plasma activated using an oxygen plasma.

5. The method of claim 1 , wherein the surfaces of the ink pathway are comprised of at least one of: silicon, silicon oxide, silicon nitride and one or more polymers.

6. The method of claim 5 , wherein said one or more polymers are selected from the group consisting of: liquid crystal polymers, polyimides, polysulfones, epoxy resins, polyolefins and polyesters.

7. The method of claim 1 , wherein the printhead is comprised of one or more printhead integrated circuits, each printhead integrated circuit comprising nozzle chambers and ink supply channels defining at least part of the ink pathway.

8. The method of claim 1 , wherein said drying surfaces comprises passing air through the ink pathway.

9. The method of claim 1 , further comprising the step of:

baking the printhead assembly.

10. The method of claim 9 , wherein said drying the surfaces includes said baking the printhead assembly.

11. The method of claim 1 , wherein the removing the protective metal film uses a basic etchant solution.

12. The method of claim 1 , wherein the removing the protective metal film uses a solution of a quaternary ammonium hydroxide.

13. The method of claim 12 , wherein said removing the protective metal film uses a solution of a tetra(C1-6 alkyl)ammonium hydroxide.

14. The method of claim 1 , wherein the alkoxylated polyethyleneimine is a polyethyleneimine having one or more primary and/or secondary amine groups functionalized with a moiety of formula (A):

wherein:

R1 is selected from the group consisting of: H and C 1-6 alkyl;

R2 is selected from the group consisting of: H, C 1-6 alkyl and —C(O)—C 1-6 alkyl; and

n is an integer from 1 to 50.

15. The method of claim 14 , wherein the alkoxylated polyethyleneimine is from 1 to 99% alkoxylated and has a molecular weight of from 300 to 1,000,000.

16. The method of claim 14 , wherein said alkoxylated polyethyleneimine is selected from the group consisting of: ethoxylated polyethyleneimine and propoxylated polyethyleneimine.

17. The method of claim 1 , wherein the solution further comprises one or more components selected from the group consisting of: C 1-6 alcohol, (C 2-6 alkylene) glycol, poly(C 2-6 alkylene) glycol, water and at least one surfactant.

18. A method of providing an inkjet printhead having a hydrophilic ink pathway and a hydrophobic ink ejection face, the method comprising the steps of:

providing the inkjet printhead comprising a nozzle plate having a hydrophobic coating and a protective metal film disposed on the hydrophobic coating;

treating the surfaces of an ink pathway in the inkjet printhead with a solution comprising an alkoxylated polyethyleneimine;

drying the surfaces; and

removing the protective metal film so as to reveal the hydrophobic coating, thereby providing the inkjet printhead having the hydrophilic ink pathway and the hydrophobic ink ejection face,

wherein said method further comprises the step of:

plasma activating the surfaces of the ink pathway before treating the surfaces with the solution comprising the alkoxylated polyethyleneimine.