Printhead including integrated circuit die cooling

1. A printhead comprising:

a substrate;

a fluidics structure attached to the substrate, the fluidics structure comprising actuators for ejecting ink from the printhead; and

an integrated circuit die attached to the substrate, the integrated circuit die for driving the actuators, the integrated circuit die cooled by a coolant contacting the integrated circuit die and flowing through the substrate.

2. The printhead of claim 1 , wherein the coolant comprises a non-ink fluid,

wherein the substrate comprises an ink inlet for supplying ink to the fluidics structure and an ink outlet for recirculating ink from the fluidics structure, and

wherein the substrate comprises a coolant inlet and a coolant outlet for supplying coolant to the integrated circuit die.

3. The printhead of claim 2 , where the coolant inlet is closer to the fluidic structure than the coolant outlet.

4. The printhead of claim 1 , wherein the coolant comprises a non-ink fluid,

wherein the substrate comprises an ink inlet for supplying ink to the fluidics structure, and

wherein the substrate comprises a coolant inlet and a coolant outlet for supplying coolant to the integrated circuit die.

5. The printhead of claim 1 , wherein the coolant comprises ink.

6. The printhead of claim 5 , wherein the substrate comprises an ink inlet and an ink outlet for supplying ink to the fluidics structure and the integrated circuit die, and

wherein the substrate comprises a bypass ink channel for supplying ink to the integrated circuit die from the ink inlet while bypassing the fluidics structure.

7. The printhead of claim 1 , wherein the substrate comprises ink channels such that the ink flows from the fluidics structure to the integrated circuit die or from the integrated circuit die to the fluidics structure.

8. The printhead of claim 1 , wherein the fluidics structure and the integrated circuit die are formed in a single die stack.

9. A printhead comprising:

a substrate die stack;

a fluidics die stack attached to the substrate, the fluidics die stack comprising actuators for ejecting ink from the printhead, the actuators cooled by ink flowing through the fluidics die stack; and

an integrated circuit die attached to the substrate on each side of the fluidics die stack, each integrated circuit die for driving the actuators, each integrated circuit die cooled by a coolant contacting the integrated circuit die and flowing through the substrate die stack.

10. The printhead of claim 9 , wherein each integrated circuit die is attached to the substrate via an interposer for protecting the integrated circuit die from the coolant.

11. The printhead of claim 9 , wherein the coolant comprises a non-ink fluid, and

wherein each integrated circuit die is cooled by the non-ink fluid flowing from a first side of each integrated circuit die to a second side of each integrated circuit die, each first side closer to the fluidics die stack than each second side.

12. A method for cooling a printhead, the method comprising:

supplying ink to a fluidics structure through a substrate on which the fluidics structure is attached; and

supplying coolant to an integrated circuit die through the substrate on which the integrated circuit die is also attached.

13. The method of claim 12 , wherein the coolant comprises a non-ink fluid, and

wherein supplying coolant to the integrated circuit die comprises supplying the non-ink fluid to the integrated circuit die through coolant channels of the substrate from a first side of the integrated circuit die to a second side of the integrated circuit die, the first side closer to the fluidics structure than the second side.

14. The method of claim 12 , wherein supplying coolant to the integrated circuit die comprises supplying ink to the integrated circuit die.

15. The method of claim 14 , wherein supplying coolant to the integrated circuit die comprises supplying ink, which has passed through a bypass ink channel within the substrate that bypasses the fluidics structure, to the integrated circuit die.