Abstract: An ink jet printhead has improved resistance to the corrosive effects of ink by coating the surface of a photo-imageable polymer with an ink resistant film. In one described embodiment, a thermal ink jet element is formed by bonding together a channel plate and a heater plate. Resistors and electrical connections are formed in the heater plate. A polyimide layer is formed so as to overlie the heater plate to protect the electrical elements while providing pit structure for the heater and for ink flow bypass. A tantalum film is formed on the surface of the polyimide layer to protect the layer from the effects of corrosive ink. In another embodiment, the ink resistant film is amorphous carbon or silicon nitride.

Abstract: In a thermal ink jet printhead with a protective layer, the protective layer is made of a thin film material having a melting point not less than about 1000.degree. C. A deposition process for preparing the thin film material produces a thin film material having, at an operating temperature for the thermal ink jet printer, a thermal conductivity coefficient not less than about 10 W/m.K, a compressive yield strength not less than about 1400 MPa, and a compressive residual stress of not greater than about 1200 MPa. The protective layer is smooth, substantially free of pores and impervious to stress corrosion or hydrogen stress cracking at a hydrogen uptake rate of less than about 5 ppm. The protective layer may also contain an adhesion enhancing region between the protective layer and an underlying layer or an anodic region contiguous with an underlying thin film material of the protective layer.

Abstract: An improved ink jet printhead is disclosed of the type having a plurality of parallel ink flow channels which terminate with an ink droplet emitting nozzle, a heating element with a cavitational protective layer thereover located in each channel, and MOS electronic circuitry monolithically integrated within the printhead for applying electrical pulses to the heating elements. The pulsed heating elements produce bubbles momentarily on the protective layer of the heating elements which expel ink droplets from the nozzles. The improvement is obtained by providing multi-layer ionic passivation of the MOS electronic circuitry which is exposable to the ink. This is accomplished through the deposition of a multi-layered, thin film insulative coating thereon consisting of a first layer of doped or undoped silicon dioxide having a thickness of 200 .ANG. to 2 .mu.m followed by a second layer of plasma nitride having a thickness of 1000 .ANG. to 3 .mu.m.