Patent ID: 7134745

Claim:
An ink jet printhead comprising: a plurality of nozzles, each nozzle having a respective bubble forming chamber; a heater disposed in each of the bubble forming chambers respectively, the heater having a pair of electrodes and at least one heater element configured as a beam suspended across the bubble forming chamber by the electrodes for thermal contact with a bubble forming liquid; integrated circuit metalization layers corresponding to each of the nozzles, the metalization layers supplying electrical energy to the heater; such that, heating the heater element to a temperature above the boiling point of the bubble forming liquid forms a gas bubble that causes the ejection of a drop of an ejectable liquid through the nozzle corresponding to that heater element; wherein, the heater and the integrated circuit metalization layers are substantially planar and at least partially overlapping, the metallization layers electrically connected to the heater electrodes by vias, the cross sectional area of all the vias being greater than 50% of the surface area of one side of the heater.