Patent Application
20060146091
The disclosure relates to micro-fluid ejection devices, and in particular to improved methods for making micro-fluid ejection head structures.
Micro-fluid ejection heads are useful for ejecting a variety of fluids including inks, cooling fluids, pharmaceuticals, lubricants and the like. A widely used micro-fluid ejection head is in an ink jet printer. Ink jet printers continue to be improved as the technology for making the micro-fluid ejection heads continues to advance. New techniques are constantly being developed to provide low cost, highly reliable printers which approach the speed and quality of laser printers. An added benefit of ink jet printers is that color images can be produced at a fraction of the cost of laser printers with as good or better quality than laser printers. All of the foregoing benefits exhibited by ink jet printers have also increased the competitiveness of suppliers to provide comparable printers in a more cost efficient manner than their competitors.
One area of improvement in the printers is in the print engine or micro-fluid ejection head itself. This seemingly simple device is a relatively complicated structure containing electrical circuits, ink passageways and a variety of tiny parts assembled with precision to provide a powerful, yet versatile micro-fluid ejection head. The components of the ejection head must cooperate with each other and with a variety of ink formulations to provide the desired print properties. Accordingly, it is important to match the ejection head components to the ink and the duty cycle demanded by the printer. Slight variations in production quality can have a tremendous influence on the product yield and resulting printer performance.
In an exemplary embodiment, the disclosure provides a method of making a micro-fluid ejection head structure. Such a method can include positioning a semiconductor substrate having a fluid feed slot over a nozzle plate film in a bonding orientation therewith such that the substrate overlies the nozzle plate film and the device side of the substrate is substantially downwardly facing so that gravitational forces inhibit deformation of portions of the nozzle plate film toward the device side of the substrate.
In another embodiment, there is provided a method of bonding a deformable film to a fluid flow structure in order to inhibit blocking of flow paths in the fluid flow structure. The method can include applying the fluid flow structure to the deformable film by substantially downward movement of the fluid flow structure toward the film. During the downward movement of the structure gravitational forces inhibit deformation of portions of the film into portions of the flow paths of the fluid flow structure sufficient. The film is then bonded to the structure.
An advantage of at least some of the embodiments described herein can be that sagging and other deformations of a nozzle plate film into slots or flow feature areas of the structure, as occurs with other techniques, is substantially avoided.
Further features and advantages of the disclosed embodiments will become apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale, wherein like reference numbers indicate like elements through the several views, and wherein:
The invention relates to improvements in the manufacture of micro-fluid ejection head of the type having a nozzle plate provided by a film having nozzle holes formed thereon and applied over fluid supply slots defined in a semiconductor substrate. For example, with reference to
In a first step (
The semiconductor substrate 4 is generally made of silicon and contains various passivation layers, conductive metal layers, resistive layers, insulative layers and protective layers deposited on a device surface thereof. Fluid ejection actuators formed on the device surface of the substrate 4 may be thermal actuators or piezoelectric actuators. For thermal actuators, individual heater resistors are defined in the resistive layers and each heater resistor corresponds to a nozzle hole in the nozzle plate film 8 for heating and ejecting fluid from the ejection head toward a desired medium or target.
In this regard, the photoimageable layer 2 can be either a positive or negative photoresist material applied as a wet layer as by spin coating, spray coating or the like, or as provided by a dry film photoresist material. In the case of a dry film photoresist material to provide the layer 2, the substrate 4 having the layer 2 thereon can be passed between heated rollers 12 of a hot roll laminator (
The nozzle plate film 8 may also be a dry film photoresist material which may include one or more layers of photoresist material and may be imaged through a photomask and developed to form the nozzle holes. The film 8 can be bonded to the layer 2 by passing the film/layer/substrate 8/2/4 composite between heated rollers 14 of a hot roll laminator (
A problem associated with the aforementioned manufacturing technique(s), especially in the attachment of the nozzle plate film 8 as shown in
With reference to
For example, in
The nozzle plate film 20 may be provided by a wide variety of materials that may be provided as a dry film for lamination to the substrate 22. Such materials, include but are not limited to epoxies, acrylates, polyimides and the like. Such films 20 are relatively thin and have a thickness ranging from about 5 to about 100 microns. In some exemplary embodiments, the nozzle plate film 20 contains only nozzle holes and a separate flow feature layer 28 is applied to the substrate to provide flow features 30, including fluid chambers and fluid flow channels for flow of fluid to ejection devices on the device side 26 of the substrate 22. In other embodiments, the nozzle plate film 20 has a thickness sufficient to provide nozzle holes and the flow features 30 therein.
In an exemplary embodiment, the nozzle plate film 20 is a dry film photoresist material which may be imaged through a photomask and developed to form nozzle holes therein. Typical dry film photoresist materials which may be used include, but are not limited to, photoresist materials available from E. I. DuPont de Nemours and Company of Wilmington, Del. under the trade names RISTON, EMS 314-98 from EMS, Inc. of Delaware, Ohio, and ORDYL PR100 from Tokyo Ohka Kobyo Co., LTD. Kanagawa, Japan which act as adhesive photoresist materials. In such an embodiment, the nozzle plate film 20 can be applied to the separate flow feature layer 28.
In another embodiment, the flow features 30 can be formed, as by photoresist methods, in the flow feature layer 28 attached to the device side 26 of the substrate 22. In such embodiment, the flow feature layer 28 may be provided by a positive or negative photoresist material applied to the substrate 22 as a wet layer by a spin coating process, a spray coating process, or the like, or the flow feature layer 28 may be applied to the substrate 22 as a dry film photoresist material. Examples of suitable photoresist materials, include but are not limited to acrylic, epoxy, and polyimide-based photoresists such as the photoresist materials available from Clariant Corporation of Somerville, N.J. under the trade names AZ4620 and AZ1512. Other photoresist materials are available from Shell Chemical Company of Houston, Tex. under the trade name EPON SU8 and photoresist materials available from Olin Hunt Specialty Products, Inc. which is a subsidiary of the Olin Corporation of West Paterson, N.J. under the trade name WAYCOAT. An example of a polyimide based photoresist is HD4000 from HD Microsystems of Parlin, N.J. A preferred photoresist material includes from about 10 to about 20 percent by weight difunctional epoxy compound, less than about 4.5 percent by weight multifunctional crosslinking epoxy compound, from about 1 to about 10 percent by weight photoinitiator capable of generating a cation and from about 20 to about 90 percent by weight non-photoreactive solvent as described in U.S. Pat. No. 5,907,333 to Patil et al., the disclosure of which is incorporated by reference herein as if fully set forth.
The flow features 30 may be formed in the flow feature layer 28 in a manner, such as described in connection with
The disclosure provides improved methods for applying the nozzle plate films 20 to the semiconductor substrate 22. As described above, the substrate 22 has one or more fluid feed slots 24 therein for flow of fluid to ejection actuator devices on the device side 26 of the substrate. The nozzle plate film 20 is applied to the flow feature layer 28 on the substrate 22 so that the nozzles of the nozzle plate film 20 are in flow communication with the fluid feed slots 24 in the substrate 22. The slots 24 may be formed in the substrate 22 prior to or after attachment of the film 20 to the flow feature layer 28.
In a first embodiment, a thermocompression bonder instead of a hot roll laminator is used to attach the substrate 22 with flow feature layer 28 thereon and nozzle plate film 20 to one another. The orientation of the substrate/flow feature layer 22/28 to the nozzle plate film 20 during the bonding step is shown in
With reference to
In yet another embodiment, and as depicted in
In yet another alternative embodiment of the disclosure, the film 20 may be laminated to the substrate/flow feature layer 22/28 in the absence of heat. For example, the film 20 may be placed on a support, such as the plate 32 (
In this regard, it will be understood that “downwardly” refers to an orientation such that gravitational forces substantially inhibit otherwise unforced movement of the film 20 toward the device side 26 of the substrate 22. As will be appreciated in the case of other methods such as described in connection with
To provide a micro-fluid ejection device, the substrate/flow feature layer/nozzle plate film assembly 22/28/20 prepared in accordance with the disclosure may be attached in a well known manner to a chip pocket in a cartridge body to form an ejection head. Fluid to be ejected is supplied to the substrate/flow feature layer/nozzle plate assembly from a fluid reservoir in the cartridge body generally opposite the chip pocket.
The cartridge body can be made of a metal or a polymeric material selected from the group consisting of amorphous thermoplastic polyetherimide available from G.E. Plastics of Huntersville, N.C. under the trade name ULTEM 1010, glass filled thermoplastic polyethylene terephthalate resin available from E. I. du Pont de Nemours and Company of Wilmington, Del. under the trade name RYNITE, syndiotactic polystyrene containing glass fiber available from Dow Chemical Company of Midland, Mich. under the trade name QUESTRA, polyphenylene oxide/high impact polystyrene resin blend available from G.E. Plastics under the trade names NORYL SEl and polyamide/polyphenylene ether resin available from G.E. Plastics under the trade name NORYL GTX. An exemplary polymeric material for making the cartridge body is NORYL SEl polymer.
The semiconductor substrate 22 can be a silicon semiconductor substrate containing a plurality of fluid ejection actuators such as piezoelectric devices or heater resistors formed on the device side 26 of the substrate 22. Upon activation of heater resistors, fluid supplied through the slots 24 in the semiconductor substrate 22 is caused to be ejected through nozzle holes in the nozzle plate film 20. The fluid ejection actuators, such as heater resistors, are formed on the device side 26 of the semiconductor substrate 22 by well known semiconductor manufacturing techniques.
The semiconductor substrate 22 is relatively small in size and typically has overall dimensions ranging from about 2 to about 8 millimeters wide by about 10 to about 20 millimeters long and from about 0.4 to about 0.8 mm thick. The fluid supply slots 24 are typically grit-blasted in the semiconductor substrate 22, etched in the substrate 22 by a chemical wet etch technique, or made by a dry etch process selected from reactive ion etching (RIE) or deep reactive ion etching (DRIE), inductively coupled plasma etching, and the like. Such slots 24 typically have dimensions of about 9.7 millimeters long and 0.39 millimeters wide.
The device side 26 of the substrate 22 can also contain electrical tracing(s) from the heater resistors to contact pads used for connecting the substrate 22 to a flexible circuit or a tape automated bonding (TAB) circuit for supplying electrical impulses from a fluid ejection controller to activate one or more of the heaters or other fluid ejection actuators located on the device side 26 of the substrate 22 The flexible circuit or TAB circuit may be attached to the cartridge body as by use of a heat activated or pressure sensitive adhesive. Exemplary pressure sensitive adhesives include, but are not limited to phenolic butyral adhesives, acrylic based pressure sensitive adhesives such as AEROSET 1848 available from Ashland Chemicals of Ashland, Ky. and phenolic blend adhesives such as SCOTCH WELD 583 available from 3M Corporation of St. Paul, Minn. In an exemplary embodiment, the pressure sensitive adhesive has a thickness ranging from about 25 to about 200 microns.
The disclosed embodiments, as set forth therein, can enable attachment of nozzle plate films in a manner that avoids many of the shortcomings of other manufacturing methods thereby providing an advantage over other micro-fluid ejection head manufacturing processes.
Having described various aspects and embodiments of the disclosure and several advantages thereof, it will be recognized by those of ordinary skills that the embodiments are susceptible to various modifications, substitutions and revisions within the spirit and scope of the appended claims.
