Liquid purification or separation – Magnetic
Reexamination Certificate
1999-07-13
2001-08-07
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Magnetic
C210S695000
Reexamination Certificate
active
06270666
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for the magnetic treatment of fluids through the application of magnetic fields to the fluid flowing through conduits, and the method for using that apparatus.
BACKGROUND OF THE INVENTION
Alkaline-developing photoresists are used for patterning, for example, chemical-milling and the production of printed wiring boards. As foaming during production is detrimental to the production of printed wiring boards, measures have conventionally been taken to suppress foaming through the addition of antifoaming agents. The ingredients of certain antifoaming agents, such as polyoxyalkylene ethers, glycerol monostearate, polyoxyethylene sorbitan monostearate, and coconut alcohol, are themselves contaminants in developers and the products of these printed wiring boards.
On the other hand, some ingredients of photoresists, such as polymers having a structure unit of styrenes, methyl methacrylate, ethyl acrylate, and methacrylic acid, are separated and deposited on the wall of conduits. The deposits are also contaminants in developers and the products. In order to remove the separated materials described above, 3% aqueous hydrochloric-acid solution and commercial cleaning solution; some cleaning solution containing caustic soda, sodium acetate, butyldiglycol, or surfactants; and those including hydrochloric acid or hydroxycarboxylic acid, as have conventionally been used. However, these methods involve the high costs of chemical cleansing and waste treatment, and are may not be sufficiently effective, depending on the photoresist ingredients.
In this technological environment, a magnetic water-treatment apparatus is publicly known. As the apparatus separates the association of clustered water molecules in order to reactivate them, it may also be utilized to perform defoaming in the development step described above if it functions as expected. However, as the fluid to be treated is exposed to magnetic flux generated between a pair of magnets positioned on opposite ends of a flow of water in the case of the water-treatment apparatus described above, the pair of magnets must be positioned so as to face each other. Therefore, a strong magnetic field also exists in regions other than the area under examination, resulting in the problems of a low efficiency in magnetic-field utilization and a significant loss in magnetic force. In addition, utilization of a water-treatment apparatus such as that described above, comprising a uniform magnetic field only, cannot be expected to have a significant effect.
U.S. Pat. No. 5,074,998 is an exemplary invention intended to prevent the deposition of scale inside conduits. The invention has a constitution in which solenoid-type electric coils are positioned alongside and outside or inside the conduit, a magnetic field, generated by charging the electric coils, is applied to the fluid in the conduit. Control of the strength of this magnetic field is also described in the invention. This is done by adjusting the amplifying-signal electric current of the coil to the characteristic frequency of the scale-forming substance. The fluid is exposed to a magnetic field only once while it flows through a conduit utilizing an apparatus of the invention described above.
SUMMARY OF THE INVENTION
The present invention was developed in view of the above-mentioned points, and its object is to enable magnetic-force-based kinetic energy to affect fluids flowing through conduits.
Another object of the present invention is to facilitate the removal of contaminants such as scale-forming substances existing in the fluid, by changing the coarseness (structural coarseness) of the contaminants, and to change the magnetic-force-based kinetic energy acting on the fluid in order to improve the characteristics of the fluid.
Another object of the present invention is to solve the problem of contamination of the developer and the developed products by controlling and removing foams that are detrimental to the development process without using conventional antifoaming agents, and to effectively remove insoluble substances in the development process that could not be removed by conventional methods.
Another object of the present invention is to enable stable product control in chemical milling and the production of printed wiring boards.
Another object of the present invention is to prevent so called scale that is deposited on the wall of conduits, etc. of photoresist developers such as in the development process, making it easier to clean the alkaline developer.
These and other objects have been attained by using magnetic units in which the ends of each of the yokes are arranged alternately at the N and S poles, and the other ends of said yokes being arranged so as to face each other, in order to form magnetic circuits in which magnetic flux can circulate, resulting in the positioning of the magnetic treatment part of fluids between said other ends of said yokes, with a plurality of said magnetic units being arranged such that the directions of magnetic flux generated at said parts for magnetic treatment change along the flow path of said fluids.
Thus, the present invention is characterized by the inverse application of a magnetic field to a fluid. The inverse application of a magnetic field in the present invention means switching the polarity of magnetic fields in certain regions. As a result, for example, the magnetic flux may point downward in a certain region, while it points upward in adjacent regions. Therefore, when a fluid such as developing solution passes through regions with different magnetic-flux directions, as described above, it is affected by changes in kinetic energy due to the 180-degree changes in the magnetic flux resulting from the polarity change in the magnetic fields. A magnetic field with magnetic flux having alternating directions will be referred to as an alternating magnetic field in the present invention. To form the 180 degree changes in the magnetic flux, it is desirable to insert non-magnetic spacer between adjacent magnetic units to generate an alternative magnetic field stably.
Although the present invention is common to the conventional magnet-type water-treatment apparatus, it also utilizes the effect of the changes in kinetic energy accompanying the inversion of magnetic polarity. Thus, according to the present invention, both the changing magnetic energy and kinetic energy may be applied to water molecules and the like in the developing solution.
The magnetic circuit described above contains blocks of magnetic material polarized to the N pole and the S pole on its largest face, and a yoke with its end magnetically attracted to said polarized surface and other parts arranged so as to surround the flow of the developing solution, and this magnetic circuit configured so that the magnetic flux circulates. The strength of the magnetic flux per unit area is maximized by polarizing the N pole and the pole in the largest area of the blocks of strongly magnetized magnetic material (permanent magnet), enabling efficient magnetization of fluids or of other objects such as solvents, solutes, dispersion, etc.
The present invention is also applicable to the removing of scale containing components such as polymeric polymerizing binders, polymerizable substances, and additives deposited on the flow paths and the tank of developing solutions in the developer, wherein it is desirable to use as cleaning liquid aqueous solutions containing one or more than one ingredient of the components polyearboxylic acid, malic acid, EDTA, and saponin, and to remove the insoluble deposits by exposing said aqueous solution to an alternating magnetic field and then flowing it onto the flow paths and into the developing-solution tank.
The scale formed by deposition due to the use of developers mainly contain one or more than one ingredient of the following: polymeric binders, polymerizable substances, and additives. The polymeric binder used is typically an acrylic ester copolymer, styrene-methyl methacrylate copolymer, or
Kamibayashi Yoshiji
Kiuchi Takeshi
Sanefuji Mitsutoshi
Jacobson & Holman PLLC
Reifsnyder David A.
Toushin Keisoku Corp.
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