Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1999-05-17
2001-02-13
Wu, Shean C. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S270100, C430S286100, C522S071000, C522S162000, C522S163000, C522S164000, C522S165000, C522S166000, C528S125000, C528S126000, C528S127000, C528S128000, C528S174000, C528S176000, C528S373000, C528S423000
Reexamination Certificate
active
06187512
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a process for preparing halomethylated high performance polymers and to methods for making photoresists with curable derivatives of these polymers. The present invention is also directed to processes for preparing improved photoresist compositions and improved thermal ink jet printheads with these polymers. One embodiment of the present invention is directed to a process which comprises reacting a polymer of the general formula
wherein x is an integer of 0 or 1, A is
or mixtures thereof, B is
wherein v is an integer of from 1 to about 20,
wherein z is an integer of from 2 to about 20,
wherein u is an integer of from 1 to about 20,
wherein w is an integer of from 1 to about 20,
or mixtures thereof, and n is an integer representing the number of repeating monomer units, with a halomethyl alkyl ether, an acetyl halide, and methanol in the presence of a halogen-containing Lewis acid catalyst, thereby forming a halomethylated polymer. Another embodiment of the present invention is directed to a process which comprises preparing a halomethylated polymer by the aforementioned process and subsequently converting at least some of the halomethyl groups to photosensitivity-imparting groups which enable crosslinking or chain extension of the polymer upon exposure to actinic radiation, thereby forming a photopatternable polymer. Yet another embodiment of the present invention is directed to an ink jet printhead containing a halomethylated polymer made by the aforementioned process. Still another embodiment of the present invention is directed to processes which comprise causing the either the halomethylated polymer or the photosensitivity-imparting group substituted polymer to become crosslinked or chain extended by imagewise exposure to actinic radiation in an image pattern.
In microelectronics applications, there is a great need for low dielectric constant, high glass transition temperature, thermally stable, photopatternable polymers for use as interlayer dielectric layers and as passivation layers which protect microelectronic circuitry. Poly(imides) are widely used to satisfy these needs; these materials, however, have disadvantageous characteristics such as relatively high water sorption and hydrolytic instability. There is thus a need for high performance polymers which can be effectively photopatterned and developed at high resolution.
One particular application for such materials is the fabrication of ink jet printheads. Ink jet printing systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field which adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
Since drop-on-demand systems require no ink recovery, charging, or deflection, the system is much simpler than the continuous stream type. There are different types of drop-on-demand ink jet systems. One type of drop-on-demand system has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. The relatively large size of the transducer prevents close spacing of the nozzles, and physical limitations of the transducer result in low ink drop velocity. Low drop velocity seriously diminishes tolerances for drop velocity variation and directionality, thus impacting the system's ability to produce high quality copies. Drop-on-demand systems which use piezoelectric devices to expel the droplets also suffer the disadvantage of a slow printing speed.
The other type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets and allows very close spacing of nozzles. The major components of this type of drop-on-demand system are an ink filled channel having a nozzle on one end and a heat generating resistor near the nozzle. Printing signals representing digital information originate an electric current pulse in a resistive layer within each ink passageway near the orifice or nozzle, causing the ink in the immediate vicinity to vaporize almost instantaneously and create a bubble. The ink at the orifice is forced out as a propelled droplet as the bubble expands. When the hydrodynamic motion of the ink stops, the process is ready to start all over again. With the introduction of a droplet ejection system based upon thermally generated bubbles, commonly referred to as the “bubble jet” system, the drop-on-demand ink jet printers provide simpler, lower cost devices than their continuous stream counterparts, and yet have substantially the same high speed printing capability.
The operating sequence of the bubble jet system begins with a current pulse through the resistive layer in the ink filled channel, the resistive layer being in close proximity to the orifice or nozzle for that channel. Heat is transferred from the resistor to the ink. The ink becomes superheated far above its normal boiling point, and for water based ink, finally reaches the critical temperature for bubble formation or nucleation of around 280° C. Once nucleated, the bubble or water vapor thermally isolates the ink from the heater and no further heat can be applied to the ink. This bubble expands until all the heat stored in the ink in excess of the normal boiling point diffuses away or is used to convert liquid to vapor, which removes heat due to heat of vaporization. The expansion of the bubble forces a droplet of ink out of the nozzle, and once the excess heat is removed, the bubble collapses. At this point, the resistor is no longer being heated because the current pulse has passed and, concurrently with the bubble collapse, the droplet is propelled at a high rate of speed in a direction towards a recording medium. The surface of the printhead encounters a severe cavitational force by the collapse of the bubble, which tends to erode it. Subsequently, the ink channel refills by capillary action. This entire bubble formation and collapse sequence occurs in about 10 microseconds. The channel can be refired after 100 to 500 microseconds minimum dwell time to enable the channel to be refilled and to enable the dynamic refilling factors to become somewhat dampened. Thermal ink jet equipment and processes are well known and are described in, for example, U.S. Pat. Nos. 4,601,777, 4,251,824, 4,410,899, 4,412,224, 4,532,530, and 4,774,530, the disclosures of each of which are totally incorporated herein by reference.
The present invention is suitable for ink jet printing processes, including drop-on-demand systems such as thermal ink jet printing, piezoelectric drop-on-demand printing, and the like.
In ink jet printing, a printhead is usually provided having one or more ink-filled channels communicating with an ink supply chamber at one end and having an opening at the opposite end, referred to as a nozzle. These printheads form images on a recording medium such as paper by expelling droplets of ink from the nozzles onto the recording medium. The ink forms a meniscus at each nozzle prior to being expelled in the form of a droplet. After a droplet is expelled, additional ink surges to the nozzle to reform the meniscus.
In thermal ink jet printing, a thermal energy generator, usually a resistor, is located in the channels near the nozzles a predetermined distance therefrom. The resistors are individually addressed with a current pulse to momentarily vaporize the ink and form
Foucher Daniel A.
Janezic Roger T.
Luca David J.
Smith Thomas W.
Stoffel Nancy C.
Byorick Judith L.
Wu Shean C.
Xerox Corporation
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