Not Applicable
Not Applicable
Not Applicable
1. Field of Invention
This application relates to the sequential placement of droplets of two or more liquids to a target location on a surface for the purpose of: removing material from the surface, as for the cleaning of delicate surfaces such as fossils, art objects, or semiconductor devices; adding material, such as precipitates, polymers, and agglomerates, to the surface; or using the surface to catalyze a reaction involving substances contained in the liquids, while minimizing the formation of side products.
2. Prior Art
Numerous methods exist for the application of a single liquid to a surface: manual or automated application with cloth, tissue, sponges, rollers, brushes or other applicators; droppers; streaming and aerosol sprayers; pressurized nozzles; and droplet jets. These methods do not readily facilitate rapid repeated alternate or sequential application of more than one liquid to the same place, location, or target. Devices which apply a single liquid to a surface depend upon a property of the liquid itself, such as drying and curing or dissolving and rinsing, to produce a desired effect of coating or cleaning on the surface. Inkjet technology can apply more than one color ink to a target location, but does not do so repeatedly to any great extent, and is designed for use with specially formulated inks rather than a variety of liquid solvents and reactive liquid chemical solutions. The ink droplets, even if applied to the same target location, do not produce their desired result by means of chemical reaction with one another while mixing on the surface to which they have been applied.
Different substances on the same surface may require different liquid solvents for dissolving and removing them. The power of solvation of some liquid solvents is reduced by mixing with another liquid solvent, so that a mixture of two or more liquid solvents is less effective than a separate application of each liquid solvent. Similar to liquid solvents, or more so in this respect, would be liquids containing acids and bases, which would neutralize each other if mixed before application to the surface. Material on a surface may in some cases contain components which yield to two different liquid solvents or other active liquid chemicals, which two liquid solvents or chemicals interfere with each other if applied simultaneously. In other cases a strongly solvent or reactive liquid may be required to cause any significant removal reaction, but must not be left in contact with the surface for too long, but must be applied and rinsed away or neutralized in a rapid and metered manner.
Semiconductor cleaning baths typically use one or more liquids in sequence, each liquid removing specific surface components. Components not yet removed by a subsequent suitable cleaning agent liquid may interfere with a current cleaning agent liquid.
Polymerizing and agglomerating mixtures that cure too rapidly are difficult or impossible to use, or at least require disposable one use mixing nozzles. Some glues cure so rapidly upon mixing of the two components that the compounds are mixed by simultaneous injection into a special tube or nozzle from which the mixed product is dispensed; such dispensers do not allow much hesitation, as for examination of how the material is being applied, before the mixing nozzle becomes clogged, and otherwise require attention to dexterous operation. This method excludes epoxies which cure yet more rapidly.
Liquid solutions which when combined produce a precipitate will in general do so with such rapidity that only traces if any of the precipitate would deposit onto a surface to which the previously mixed liquid solutions were subsequently applied. Otherwise, the alternate application of the liquid solutions by current means is tedious and results in scant precipitated deposits on the surface.
Plasma techniques can be used for cleaning and depositing, but the ionized gasses may be unsuitable for some surfaces, and chemically alter some deposit materials.
Both for methods of removal, as by solvents, and basic, acidic, oxidizing, reducing, enzymatic or other chemically active liquid solutions, and for methods of deposit, as of epoxies, polymers in general, organic adhesive aggregates, or precipitates, the alternate or sequential application of liquids without mechanical automation is tedious and of uncertain uniformity. Moreover, the action to be accomplished on the surface, whether of removal or of deposit, may require so many alternate applications as to not be expeditiously accomplished even by automated mechanical movement of the target surface or of the solution application baths or nozzles.
Some chemical reactions are catalyzed heterolytically by bringing the reactants into contact with a surface made up of a catalyzing material. In some cases it is desirable to bring the reactants into contact with a catalyzing surface as rapidly as possible so as to preclude the formation of undesirable side products caused by ordinary mixing of the liquid solutions containing the two reactants. A streaming application of two reactant solutions to a catalytic surface may involve some pre-mixing of the liquid solutions prior to intimate contact with the catalytic surface, with formation of undesirable side products.
This device and method allows rapid efficient alternate or sequential application of liquid cleaning agents to a surface, so as to maximize the total cleaning or removal effect despite surface deposits resistant to and thus interfering with any particular liquid cleaning agent. This device and method can be easily combined with current spinning substrate methods of semiconductor cleaning. This device and method allows for the precise adjustment of cleaning liquids to be applied to delicate surfaces such as artwork and fossils. The force with which droplets of removal liquids are applied to a surface can be varied for the application. In some embodiments, the alternate or sequential application of droplets is combined with a pulsed or continuous flow of a gas or gasses, which may include ionized gas or plasma. The force with which a gas or gas stream is applied can be varied for the application. This device or method allows flexibility, efficiency, and fine control in the cleaning or other surface removal of moderately small surfaces having a wide variety of physical and chemical characteristics.
Because the liquid components are not mixed prior to contact with the surface, this device or method facilitates the application of rapid curing polymeric or other aggregative substances without clogging of an applicator nozzle. Without using high temperature or ionized gasses, chemically sensitive precipitates can be deposited as an accumulated layer on surfaces which may themselves be sensitive to high temperatures or ionized charges. Radiations which facilitate the formation of a desired deposit product can be applied during the depositing process, rather than afterwards, allowing better penetration of the applied substances. The common target of the liquid orifices allows rapid application of more than one liquid without movement of the nozzle head or the object containing the target surface.
This device or method allows an individual liquid droplet applied to a catalytic surface to be flattened into a thin film on that catalytic surface before the application of a droplet of a reacting liquid, thereby minimizing the production of side products. Moreover, the catalytic surface can be periodically cleaned or restored while remaining in place.
In a basic embodiment, droplets of two liquids are repeatedly applied to a surface, or target area, in such a way that the droplets essentially do not contact each other prior to landing on the surface. Small nozzles directed at the target area apply the droplets, which nozzles are connected with suitable tubing to valves or pumps operated by an electrical or electronic control unit. The pumps or valves are fed through tubing from containers, which may be elevated or pressurized, holding the two liquids. The resulting action depends upon the liquids and the surface, and falls into one of three categories: removal of substance from the surface, as by solvation or other chemical action; deposit of material upon the surface, as by precipitation or polymerization; catalytic reaction of components of the liquids caused by properties of the surface. In further embodiments additional elements are added to facilitate a desired action: continuous, pulsed, or interrupting flows of air or another gas to the target area of the surface; sonic, ultrasonic, or any of various electromagnetic radiations directed at the target surface; temperature control of the liquids, and of the gasses if any, by means of heating, cooling, or insulation elements applied to the containers or along the tubing paths. Suction may be applied for removing the liquids from the area of application. Multiple nozzles, with attendant containers, tubing, valves or pumps, and control circuitry, are used for application of droplets of more than two liquids.
The following description details those embodiments currently conceived as best instances, and although they do contain indications of useful variety and extension, this should be considered illustrative and not limiting, with the full scope of the invention delineated in the appended claims.
A first embodiment of the device comprises a nozzle assembly,
The liquid orifices 1 and 2 are preferentially made of PTFE because of the chemical resistance of PTFE, and because the hydrophobic characteristic of PTFE prevents or reduces dribbling at the liquid orifices 1 and 2 in cases where the liquids 14 and 15 are aqueous solutions. The liquid orifices have an internal diameter ranging from 0.025 millimeter to 0.4 millimeter, depending upon the liquid's viscosity and the air or gas pressure supplied to the container. For aqueous solutions 0.2 millimeter (0.008 inch) to 0.254 millimeter (0.01 inch) are satisfactory inner diameters for the liquid orifices. The cross sectional shape of the liquid orifices can be circular, oval or another shape chosen to reduce dribbling and provide for the reliable emission or ejection of a discreet individual droplet when the corresponding liquid valve is briefly opened. The surface around the liquid orifice should be as smooth and even as possible. The liquid orifices are angled toward each other such that liquid emitted from the liquid orifices will land at the same target location at a predetermined distance from the liquid orifices; this is the target surface, or location, as previously mentioned in the introductory paragraph to the specifications section. The liquid orifices are placed nearly side by side, with sufficient separation, typically about 0.5 millimeter to 1.5 millimeter, to avoid cross contamination from any dribbling, and close enough that the angle by which the liquid orifices point towards each other allows some variation in the distance from the liquid orifices to the target surface, or location.
Each liquid orifice, liquid orifice support, and liquid path can be made of lengths of tubing of different inner and outer diameters such as to fit tightly into each other, as by a luer form of connection, so that the connection ports 8 and 9 can be joined to the path of liquid A 17 and the path of liquid B 16, respectively. Tubing made of PTFE can be welded together where connected using a small butane torch. The lengths of tubing for 5 and 17, and for 6 and 16, should be made of a suitable chemically resistant material, and should be inelastic even if somewhat flexible so as to convey a discreet sharp pulse in the liquid from a liquid valve to a corresponding liquid orifice; PTFE tubing is well suited to these criteria and is available in many sizes at reasonable cost. The liquid orifice supports 3 and 4, and the nozzle assembly liquid paths 5 and 6 may be separately made of tubing held in place together with a suitable binding material or housing 7, a basic nozzle head support. Alternatively, the nozzle head is an essentially solid piece of material, preferably made of PTFE, with holes passing through it, which holes at one end form the liquid orifices, and at the other end provide for connection to the corresponding tubing. Ideally the liquid orifices are sufficiently protruding, about 2 millimeters to 10 millimeters, whether as tubes joined together or as openings in a solid piece, to reduce or eliminate dribbling. Orifices with elliptical or oval cross sections are currently found to produce the cleanest emission of droplets.
The container gas supply 10 may use bottled air or other gas, or a pump. Filters and a ballast tank or container may be included. A pressure regulator with valve and gauge may also be included. For some liquids the pressurization can be supplied by bottled compressed gas, if the use of air is chemically deleterious to the liquids, if a specific gas contributes to the chemical activity sought on the target surface, or if bottled gas is more convenient.
The pressure should be such, in consideration of the length and diameter of the type of tubing, the viscosity and surface tension of the liquids, the distance to the target, and the period during which the liquid valves are open, that as nearly as possible discreet individual droplets cleanly and completely leave the liquid orifices and land on the target surface for the most part intact. Separate regulation of the pressure applied to the containers, not shown, would be needed where the liquids have sufficiently different viscosities or flow characteristics. The liquids in the liquid containers are connected to the solenoid valves with a suitable chemically resistant tubing such as PTFE tubing, as part of the liquid paths 16 and 17.
The two channel transistorized pulse provider, or two channel pulse provider 20 in
The INVERTER circuit is primarily to isolate inputs connected to an AND GATE. A solenoid driver circuit is shown in
In
The size of the droplets is determined by the length and diameter of the liquid paths and orifices, the pressure applied to the liquid containers, the viscosity of the liquids, and the length of the positive pulses shown in 29A and 29B, as controlled by R23 in
A series of snapshot style drawings are given in
Another series of snapshot style drawings are given in
The first embodiment is suited to simple cleaning of small areas, and to the application of polymerizing and agglomerating liquids which are readily soluble in each other.
A second embodiment of the device is essentially the same as the first embodiment given above, with the addition of suction to remove liquids applied to the target, and some modification to the liquid orifices. In
The action produced by the second embodiment is essentially the same as the first, with an advantage for cleaning or other surface removal in that the liquids deposited on the surface are not allowed to spread.
Chemical actions are affected by conditions such as radiation, mixing, and temperature. A third embodiment supplements the basic design of the first embodiment with features providing radiation, mixing, and control of temperature.
In
Liquid container A 13 and liquid container B 12 have temperature jackets 89A and 89B, shown in
As shown in
The ancillary radiations control powers the ultrasonic and LED radiation sources. The power supply, switch, and voltage sources are shown in
The three path heating jacket is shown in
The effect of streaming gas is illustrated in
In
When the emission of droplets is faster and the streaming gas flow is slightly reduced a different action occurs on the target surface. In
When the emission of droplets is as fast as the preceding example and the gas flow is sufficiently stronger, each droplet has been spread into a thin film when the succeeding droplet of the other liquid lands, with a mixture of the two liquids spreading around the perimeter of the target location. In
The two channel and four channel pulse providers produce pulses having the same length on channel A and channel B, and the same length of a pause between those pulses. For some processes it would be desirable to mix a droplet of one liquid onto or with a droplet of the other liquid, and then blow the mixture away. This would require the pause after the second droplet to be longer than the pause after the first droplet, allowing the streaming gas flow more time to act. Slight differences in the response times of the liquid solenoid valves, and differences in the effective viscosity of the liquids in the liquid tubing paths, could be corrected by separately adjusting the pulse lengths on channel A and channel B. Moreover, it may be desirable to apply droplets of more than two liquids, or to periodically interrupt a repetitive droplet application to allow more time for applied radiations to have an effect, or to apply a special flow of a gas, or to apply a sequence of other liquids. The fourth embodiment is an example of addressing these considerations. The essential action retained from the preceding embodiments is that separate droplets of liquids are applied to a target surface without appreciable prior contact. Some features of the third embodiment are retained, but ancillary radiations are not shown, and streaming gas flow is continuous rather than pulsed.
The nozzle head for the fourth embodiment is shown in
The intermittent gas supply 157, in
The multichannel pulse provider makes use of circuits, called herein chainable pulse generators,
The details of the circuitry for the multichannel pulse provider are given, as follows, in
The voltage sources for the multichannel pulse provider, or MPP, are shown in
The start and stop control
A high resolution timer switch is shown in
A chainable pulse generator, CPG, is shown in
A binary coded decimal counter, BCD count, shown in
A circuit BCD counter gate is shown in
A multichannel pulse provider solenoid driver, or MPP solenoid driver, is shown in
A 1 MHz signal is produced by the circuit in
A binary coded decimal counter and two display digits is shown in
A digital display switch shown in
The general schematic for the multichannel pulse provider is shown in
The digital display switch 180 can be used while the multichannel pulse provider is operating to select a CPG to monitor, the value of a positive pulse's length being then displayed by the pulse length display 181. The length of time, up to 99 seconds, that a pulse chain has been operating can also be displayed. The actuation of a corresponding solenoid valve by a solenoid driver can be turned off with the corresponding switch SW12 in
Additional chainable pulse generators can be connected in the main loop described above as containing 167A, 167M, 167B, and 167N. Additional chainable pulse generators can be connected with the gated chainable pulse generator in counter gated CPG 175. This allows for the control of potentially elaborate configurations of applied droplets and gasses.
Sample outputs from the CPGs of multichannel pulse provider are shown in
In
A fifth embodiment of the device uses a five fold nozzle assembly shown in
Similar to the first embodiment,
Although the modular design of the multichannel pulse provider of the fourth embodiment allows potentially elaborate designs for the rest of the sequential droplet applicator, the actual hardware of the circuitry must be changed to do so. A computerized pulse provider is reconfigurable largely by merely rewriting the code of the controlling software. A further advantage is that the software can provide other output pulses for coordination with other equipment being used with the sequential droplet applicator. The computerized pulse provider for the fifth embodiment uses a 25.6 volt power supply 237 and switch SW14 shown in
Two options are shown for using a computer to control a pulse provider.
Further possible embodiments, not shown, may be formed by having different numbers of liquid orifices, paths, solenoid valves, and containers. With suitable liquids, and modified pulse providers, piezoelectric pumps or microelectronic emitters can replace or augment solenoid valves. Different patterns of sequential droplet application can be implemented. More than one gas can be used. A variety of combinations of temperature controls can be applied to the liquids and gasses. A variety of sources of radiation can be applied to the target surface. These remarks and the five embodiments given should be taken as only illustrative of the variety of applications possible; the scope should be determined by the claims and their legal equivalents.
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