Etching a substrate: processes – Forming or treating thermal ink jet article
Reexamination Certificate
1998-07-10
2001-05-15
Alanko, Anita (Department: 1746)
Etching a substrate: processes
Forming or treating thermal ink jet article
Reexamination Certificate
active
06231772
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to the manufacture of ink jet printheads and, in particular, discloses a method of manufacture of an ink jet printhead.
BACKGROUND OF THE INVENTION
Many ink jet printing mechanisms are known. Unfortunately, in mass production techniques, the production of ink jet printheads is quite difficult. For example, often, the orifice or nozzle plate is constructed separately from the ink supply and ink ejection mechanism and bonded to the mechanism at a later stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)). The separate material processing steps required in handling such precision devices often add a substantial expense in manufacturing.
Additionally, side shooting ink jet technologies (U.S. Pat. No. 4,899,181) are often used but again, this limits the amount of mass production throughput given any particular capital investment.
Additionally, more esoteric techniques are also often utilised. These can include electroforming of nickel stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)), electro-discharge machining, laser ablation (U.S. Pat. No. 5,208,604), micro-punching, etc.
The utilisation of the above techniques is likely to add substantial expense to the mass production of ink jet print heads and therefore add substantially to their final cost.
It would therefore be desirable if an efficient system for the mass production of ink jet printheads could be developed.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an alternative form of drop on demand ink jet printing which utilises a series of actuators to produce an “iris motion effect” to cause the ejection of ink from a nozzle chamber.
In accordance with a first aspect of the present invention, there is provided a method of manufacturing an iris motion ink jet printhead wherein an array of nozzles are formed on a substrate utilising planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet printheads are formed simultaneously on a single planar substrate such as a silicon wafer.
The printheads can be formed utilising standard vlsi/ulsi processing and can include integrate drive electronics formed on the same substrate. The drive electronics are preferably of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.
In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet printhead arrangement including a series of nozzle chambers, the method comprising the steps of: (a) providing an initial semiconductor wafer having an electrical circuitry layer formed thereon; (b) depositing and etching a first sacrificial material layer over the electrical circuitry layer, the etching including etching holes for nozzle chamber posts and actuator anchor points in the first sacrificial material layer located around the vias; (c) depositing and etching a first expansion material layer of a material having a high coefficient of thermal expansion, the etching including etching predetermined vias in the first expansion material layer; (d) depositing and etching a first conductive layer on the first expansion material layer, the first conductive material layer being conductively interconnected to the electrical circuitry layer via the vias; (e) depositing and etching a second expansion material layer of a material having a high coefficient of thermal expansion, the etching including forming a thermal actuator from a combination of the first and second expansion material layers and the first conductive layer; (f) depositing and etching a second sacrificial material layer, the etching forming a mould for a series of nozzle chamber posts and a series of vane elements; (g) depositing and etching a first inert material layer filling the mould; (h) depositing and etching a third sacrificial layer over the second sacrificial layer and the inert material layer, the etching including etching a mould for interconnection of nozzle chamber walls with the series of nozzle chamber posts; (i) depositing and etching a second inert material layer to form the nozzle chamber, including etching an ink ejection port in the second inert material layer; (j) etching an ink supply channel through the wafer to be interconnected with the nozzle chamber; and (k) etching away the sacrificial layers.
The vane elements are preferably arranged around the ink ejection nozzle.
The step (i) preferably includes etching a series of small holes in the inert material layer. Further, the first and second expansion material layers can comprise substantially polytetrafluoroethylene and the inert material layer can comprise substantially glass.
The ink supply channel can be formed by etching a channel from the back surface of the wafer.
The steps are preferably also utilized to simultaneously separate the wafer into separate printheads.
REFERENCES:
patent: 4094492 (1978-06-01), Beeman et al.
patent: 5828394 (1998-10-01), Khuri-Yakub et al.
patent: 5872582 (1999-02-01), Pan
patent: 5970998 (1999-10-01), Talbot et al.
Krause. P. et al “micromachined single-chip inkjet printhead” Sensors and Actuators A 53, 405-409, Jul. 1996.
Alanko Anita
Silverbrook Research Pty Ltd
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