RU2113921C1 - Cleaning liquid composition, variant thereof, and method of removing contaminations from substrate using cleaning composition - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: present invention describes cleaning liquid compositions and method of removing contaminations from substrate, e.g. printed circuit board. The claimed composition or variant thereof comprises solvating agents/detergents. Solvating agents are selected from group consisting of terpenes and terpene based compounds and detergents from group containing chlorinated hydrocarbons, chlorofluorcarbons, fluorocarbons, fluorohydrocarbons, chlorofluorohydrocarbons, alcohols, fluorinated alcohols or mixtures thereof. Composition comprises inflammable solvating agents. Claimed method of removing contaminations, e.g. soldering rosin flux from printing circuit, comprises contacting it with boiling composition containing solvating agents and detergents. EFFECT: improved properties of the cleaning composition. 33 cl, 1 dwg , 1 tbl

Description

 The invention relates to methods for removing adhesive contaminants from substrates. More specifically, the invention relates to efficient cleaning methods that use non-azeotropic mixtures of solvating and washing substances.

 The invention provides cleaning methods having characteristics and features that are very required for numerous and diverse industrial applications. For example, most metal components are treated with a grease or other process material during production, and this grease must be removed before the component is installed in the final product. It is also often required that excess rosin flux is necessarily removed from the surface of the printed circuit boards before the boards are acceptable for use. The methods of the present invention are suitable for use in these and many other applications. Thus, although the present invention is initially described here in connection with its applicability for cleaning printed circuit boards, from reading the entire application it is obvious that the invention has wider application.

 A printed circuit board, as a rule, consists of a rigid or flexible plastic-dielectric reinforced with fiberglass, having electrical contacts and conductors on one or both of its sides. Electrical components are electrically connected to these conductors and / or components using one or more soldering techniques. Most soldering technologies commonly used in industrial manufacturing processes include the step of coating the entire circuit surface of the printed circuit board, or at least a portion of it, of solder flux before performing the actual soldering operation. Rosin flux, as a rule, is used alone or in combination with activating additives based on amines, for example amine hydrochloride, for cleaning conductive metal elements and activating the production of a strong mechanical and electrical connection with solder.

 After the soldering process is completed, the presence of residual flux on the circuit board has a detrimental effect on the performance of the circuitry and components on the circuit board. Therefore, any residual flux present on the circuit board must be removed.

 The technologies used to remove adhesive residue from printed circuit boards are numerous and diverse, ranging from simple cleaning of the circuit board with brushes using a solvent to relatively complex emulsion cleaning. See Leonid, Handbook of PCB Design, Production, Components, and Assembly, Chapter 9, Pages 464 - 489 (1981). One commonly used technology is known as solvent vapor degreasing or vapor-liquid-vapor purification. In accordance with this method, the printed circuit board is in contact with: (1) relatively hot solvent-containing vapors; (2) a relatively cold solvent-containing liquid; and (3) relatively hot solvent vapor.

The equipment commonly used in connection with degreasing in solvent vapors consists of a tank having two sections. The first section of the tank contains boiling solvent, and the second section contains a relatively cold non-boiling solvent. In the vapor space above the boiling solvent, cooling coils are provided and solvent vapors are condensed on the coils and transferred to the cold solvent in the second section of the tank. Some of the cold liquid solvent is returned to the first section of the tank to maintain a sufficient amount of boiling liquid solvent. The cleaning process is usually carried out by first introducing a relatively cold, contaminated circuit board into the vapor space above the boiling solvent. Due to the temperature difference between the printed circuit board and solvent vapor, the solvent condenses on the printed circuit board and solvates the residual rosin fluxes. Thus, condensed vapors and solvated rosin fluxes are allowed to return to the first section of the tank. After the circuit board is subjected to the required amount of cleaning action, it is transferred to the second section of the tank and immersed in a cold solvent, through which the circuit board is cooled and the final cleaning that may be required is performed. The relatively cold board then re-enters the space with respect to the hot steam, where the condensing vapors perform the final board wash. Such steam-liquid-steam purification processes are described on pages 475 to 477 of the Leonida Handbook. In accordance with Leonida’s instructions, degreasing processes in solvent vapors require solvents having a boiling point below about 75 ^° C (167 ^° F).

 The types of materials that were previously used to remove residual fluxes from printed circuit boards are also numerous and diverse. For example, chlorinated hydrocarbons, aliphatic hydrocarbons, alcohols and terpenes are known solvents for rosin flux. Due to the high vapor pressure and good solvating ability in the vapor state, chlorinated hydrocarbons, including chlorofluorocarbons, are widely used in degreasing methods in solvent vapor. However, chlorinated hydrocarbons are generally relatively poor solvents of ionic residues that may be present on the circuit board or other substrate to be cleaned. See Leonida Handbook, page 466. For this and other reasons, chlorinated hydrocarbons, mainly chlorofluorocarbons, in particular, are sometimes used in combination with other low-boiling solvents.

 Mixtures containing chlorinated hydrocarbons and other low boiling solvents have been proposed for use in degreasing processes in solvent vapors. However, as a rule, the prior art did not propose, and in some cases even opposed, the use of mixtures having components with very different vapor pressures in degreasing processes. This is especially true for the prior art directed to the use of solvent mixtures that include chlorinated hydrocarbons, as illustrated, for example, in US Pat. No. 3,640,884 to Paulfield et al.

 Although solvent mixtures are used to remove rosin flux from the printed circuit board, they have the disadvantage of boiling over a wide temperature range and, therefore, are fractionated by degreasing in pairs or when using ultrasonic washing that is open to the atmosphere (column 1, rows 47 - 51). Therefore, Schulfield requires the use of tetrachlorodifluoroethane in the form of binary and triple azeotropic mixtures for use as solvents in steam degreasing processes. Other patents that describe the use of azeotropic mixtures containing chlorinated hydrocarbons as solvents in cleaning degreasing processes in solvent vapors are US Pat. No. 3,960,746 to Gorsky, US Pat. No. 3,733,218 to Began, and US Pat. No. 4,062,795 to Hutchinson. .

 Known patent GB N 2220951, which describes a liquid cleansing composition containing solvating and washing agents. However, the solvating agent of this composition is a flammable substance.

US Pat. No. 3,957,531 discloses a method for removing contaminants from a substrate, including cleaning the printed circuit board from rosin flux and grease, and a board cleaning composition comprising solvating and washing agents. In this method, the product is first treated in a boiling liquid containing solvating and washing agents, and then in a washing agent, the temperature of which is at least 50 ^° below the temperature of the boiling liquid.

 Chlorinated hydrocarbons and mixtures containing chlorinated hydrocarbons are widely used mainly as solvents in the cleaning process of printed circuit boards, but the use of such materials has recently been strongly opposed for environmental reasons. In particular, the use of chlorinated hydrocarbons, including chlorofluorocarbons, is heavily criticized by ecologists, since it was found that the dispersion of these materials in the atmosphere destroys the ozone layer. For this reason, the use of chlorinated hydrocarbons is severely limited, and in some cases completely prohibited. Thus, despite the attractive characteristics of their dissolving power, chlorinated hydrocarbons do not choose more for vapor degreasing processes. Thus, there is currently a need for an alternative to typical prior art degreasing processes that rely heavily on chlorinated hydrocarbons to provide effective purification.

 Applicants have discovered cleaning methods in which adhesive contaminants are effectively removed from a substrate. In particular, the methods of the present invention typically comprise (a) contacting the substrate with a liquid solvating agent (agent) and preferably simultaneously and / or sequentially, (b) contacting the substrate with a detergent (washing agent), wherein the vapor pressure ratio of said detergent substances to the vapor pressure of the specified solvating substance is relatively high, preferably not less than about 20.

 In accordance with one preferred aspect of the present invention, the contacting step (a) comprises contacting the substrate with a boiling liquid cleaning composition containing said solvating and washing substances. Due to the very large difference between the volatility of the solvating agent and the detergent, the solvating agent is more likely to remain in the liquid phase and the vapor space above the boiling liquid contains only very small amounts of the solvating agent and relatively high concentrations of the detergent. This is an extremely advantageous condition since the need for regeneration and recycling of the solvating agent is minimized in accordance with the preferred method of the present invention. In addition, due to the relatively non-volatile nature of the solvating agent, concern about the possible leakage of harmful solvating materials into the atmosphere is substantially reduced or eliminated altogether.

 In accordance with another preferred aspect of the present invention, the contacting step (b) comprises contacting the substrate with steam containing a detergent. This step is particularly preferably used in connection with the preferred embodiment of the boiling liquid embodiment described above, since in such embodiments the vapor space immediately above the boiling liquid contains substantial concentrations of detergent.

 A particularly preferred embodiment of the present invention comprises a cleaning composition in which the solvating and washing substances are immiscible with each other. The following are advantages associated with the use of such a composition.

 The drawing shows a semi-schematic representation of a preferred device used in connection with the methods of the present invention.

 The invention uses a combination of process steps and processing agents to effectively remove adhesive contaminants from the substrate. The term "substrate" is used here in a broad sense to mean any device or product manufactured that may be contaminated with undesirable materials. Thus, the term “substrate” includes, for example, machine parts, tools, component assemblies, and printed circuit boards. Similarly, the term “sticky contamination” is also used in a broad sense to mean, for example, unwanted materials that are not readily removable from the substrate by conventional means. Thus, the term “sticky contamination” includes organic and inorganic materials, for example, fats, oils, waxes, adhesives and rosin fluxes. However, applicants expect that the present invention will be particularly useful in connection with the cleaning of printed circuit boards from rosin fluxes and in connection with the cleaning of machine parts from wax, grease and / or oils.

 The methods of the present invention comprise the step of contacting the substrate to be cleaned with a liquid solvating agent.

 In this context, the term “solvating agent” refers to components or mixtures of components that are more prone to solvate adhesive contamination. Preferably, the solvating agents of the present invention have a solvating ability at room temperature of at least about 10, and even more preferably at least about 20. Solvating ability is determined by measuring the weight parts of the sticky impurities of the soluble in 100 weight parts of the solvating substance at room temperature. In accordance with particularly preferred embodiments, the adhesive residue is substantially completely mixed in the solvating agent in substantially any proportions.

An important feature of the present invention is the use of a solvating agent that has a relatively low vapor pressure. It has been found that the use of solvating substances with low vapor pressure in combination with other preferred features of the present invention provides purification methods that are both highly effective and environmentally friendly. In particular, solvating agents with low vapor pressure tend to remain in a liquid state. The main disadvantage of chlorinated hydrocarbon solvents of the prior art was the tendency for such compounds to leak into the environment. In addition, the greater tendency of the solvating substances of the present invention to remain in a liquid state greatly simplifies the development of the process. Accordingly, in one embodiment of the present invention, the solvating agents preferably have a vapor pressure at room temperature of not more than about 0.05 atm (about 40 mmHg) and even more preferably not more than about 0.01 atm (about 8 mmHg) . The term "room temperature" is used here to indicate a temperature of approximately 70 ^° F (approximately 20 ^° C).

 The solvating agent may also have other desirable features and characteristics. For example, the solvating agent will preferably not adversely affect the strength, integrity, or performance of the materials of construction of the substrate or components on it. As for substrates containing a printed circuit board, the solvating agent of the preferred is inert with respect to them and does not dissolve the glass fiber impregnating epoxy. The solvating agents of the present invention also preferably have a low viscosity to improve process performance and low toxicity to improve safety performance. It is very preferred that the solvating agents of the present invention are not hazardous to the atmosphere, soil and water. Chemical and photochemical stability is also another preferred feature of the solvating substances of the present invention.

 The solvating agent of the present invention is preferably selected from the group consisting of terpenes, dibasic esters, dibasic esters, petroleum solvents, alkyl substituted 2-pyrrolidones, ketones, ethers, alcohols, amines and mixtures of two or more of the above substances with terpenes, which are preferred to remove sticky impurities containing rosin flux. Although it appears that all terpenes and terpene-based compounds are suitable for use as solvating agents in accordance with the present invention, it is particularly preferred that the solvating agent is selected from the group consisting of alpha-pinene, beta-pinene, gamma-termin; delta-3-karen, limonene, dipentene, terpinolene and a mixture of two or more of the above substances with limonene and dipentene, which are preferred. As will be seen from the above examples, particularly good results were also obtained using organic esters.

 The methods of the present invention also require contacting the substrate with a detergent. As used herein, the term “detergent” refers to a component or mixture of components characterized by the ability to wash off a solvating substance and any adhesive residue dissolved by it. Other detergent characteristics will vary widely depending on factors such as, for example, the type of substrate and the solvating agent used, and all such detergents are within the scope of the present invention.

 According to a preferred embodiment, the detergent has a vapor pressure at room temperature that is relatively high compared to the vapor pressure of the solvating agent at room temperature. More specifically, it is preferable that the ratio of the vapor pressure of the detergent to the vapor pressure of the solvate is not less than about 20 and even more preferably not less than about 100. In another preferred embodiment of the present invention, the vapor pressure of the detergent at room temperature is preferably from about 0 01 atm (about 8 mmHg) to about 1 atm (about 760 mmHg) and even more preferably from about 0.1 atm Gradually 80 mmHg) to approximately 0.9 atm (approximately 680 mmHg). Applicants have found that detergents having a vapor pressure within the preferred ranges described above provide the methods of the present invention with advantageous characteristics. For example, preferred methods do not require a long drying time to remove detergent from the substrate. This advantageous feature is due to the fact that detergents with a high vapor pressure are at least partially used, which tend to easily evaporate from the substrate, thus leaving it clean and dry after the washing step. The detergents described herein having preferred vapor pressure characteristics have other advantages when used in accordance with the present methods, as described in more detail below.

 The detergents of the present invention also preferably have a slight or unknown tendency to cause ozone depletion. More specifically, it is highly preferred that detergents have an ozone depletion index (ODP) of not more than about 0.15, more preferably not more than about 0.05, and further more preferably about 0. Ozone depletion rates are published in Technical Progress On Protecting The Ozone Layer - Electronics, Degreasing and Dry Cleaning Solvents Technical Options Report United Nations Environment Program (6130189).

 Detergents containing CFC-113, CFC-114 and CFC-115 have ozone depletion rates of more than about 0.6 and are therefore not preferred in accordance with the present invention.

 As mentioned above and as described in detail below, it is particularly preferred that the solvating and washing substances are immiscible with each other. However, for some applications, it is preferred that the detergent is mainly mixed with the solvating agent. In accordance with the preferred embodiments described in detail below, the articles to be cleaned are contacted with a cleaning composition that includes both a solvating agent and a washing substance, both in a liquid state. For products to be cleaned that are fragile and thus at risk of collapse if the composition is excessively mixed, it is desirable to use a cleaning composition in which the detergent and the solvating agent are fully miscible in any proportions, since such a composition can be used more effectively with a small by stirring, or without stirring at all, than a composition that includes solvating and washing substances that are immiscible with each other rugom.

 It will be apparent to those skilled in the art that detergents are relatively non-hazardous to atmospheric ozone, at least in part, due to the absence or reduced chlorine content of the molecules constituting the detergent. However, it will also be apparent that a reduced chlorine content reduces the ability of the detergent to solvate many sticky impurities, including rosin flux. However, due to other features and characteristics of the present invention, the relatively low solvating ability of the detergents of the present invention does not impair the cleaning efficiency of the methods of the present invention. Accordingly, the primary objective of the detergents of the present invention is to wash the solvating agent from the substrate to be cleaned and it is not required that the detergents have any ability to solvate the sticky contamination, although this ability may be present in some embodiments of the present invention.

 The detergents of the present invention may also have other desirable and useful characteristics. For example, the detergent preferably does not adversely affect the strength, integrity, and performance of the materials of construction of the substrate of the components. As for the materials constituting the printed circuit board, the detergent is preferably inert to them and does not dissolve the glass fiber impregnated epoxy. It is also preferred that the detergents of the present invention have low toxicity and flammability, which improves safety performance. It is also very preferred that the detergents of the present invention are not harmful to the atmosphere, soil and water. Chemical and photochemical stability are also other preferred features and detergents of the present invention. Each of the characteristics indicated above with respect to the detergent is equally preferred for the detergent composition as a whole.

 Preferably, the detergent of the present invention is selected from the group consisting of chlorinated hydrocarbons, chlorofluorocarbons, fluorocarbons, fluorocarbons, chlorofluorocarbons, aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters and mixtures of two or more of the above substances. Even more preferably, the detergent of the present invention is selected from the group consisting of mono- or di-chlorohydrocarbons, mono- or dichlorofluorocarbons, fluorocarbons, aliphatic hydrocarbons, alcohols and mixtures of two or more of the above substances. As used herein, the term “aliphatic hydrocarbon” refers to hydrocarbons containing carbon and hydrogen and including straight and branched chains and cyclic hydrocarbons and saturated and unsaturated hydrocarbons. As used herein, the terms “fluorocarbons” and “fluorocarbons” refer to fluorinated hydrocarbons that do not contain chlorine. Perfluorohexane is preferred. Among the alcohols, isopropyl and fluorinated alcohols, for example pentafluoropropanol, are preferred. Among chlorofluorocarbons, dichloropentafluoropropane is preferred.

 A particularly preferred embodiment of the present invention comprises providing a cleaning composition in which the solvating agent and the detergent are immiscible with each other. The term “immiscible” is used here in its usual meaning, meaning that the liquid solvating agent and the liquid detergent are not miscible with each other. For example, when two liquids are poured into one vessel, each forms its own layer, and the liquid, which has a higher specific gravity, forms a layer that is located below the liquid layer having a lower specific gravity. Thus, the composition of this embodiment of the present invention at rest contains exfoliating liquid phases. The advantage of using immiscible liquids is that when used, the composition tends to boil at a relatively constant temperature, which is essentially equal to the boiling point of one detergent. In this regard, it is noted that the solvating agent is substantially insoluble in the detergent and, as a rule, contamination removed from the substrate to be treated is also substantially insoluble in the detergent even at elevated temperatures that can be used to boil the detergent . Due to the fact that the solvating and washing substances can be miscible or immiscible with each other, it must be recognized that the present invention includes within its scope a cleaning composition that contains solvating and washing substances that are partially mixed with each other or partially not mixed with each other .

 In a preferred embodiment, the liquid detergent is below the solvating agent in the composition of an exfoliating form. In such an embodiment, the relatively high boiling point solvating agent forms a protective coating or protective layer over the low boiling detergent when the composition is not used. An embodiment of the above type of composition may be provided by selecting a detergent that has a higher specific gravity than the solvating agent.

 It is particularly preferred that the detergent of the present invention is a non-aqueous detergent. As used herein, the term “non-aqueous detergent” refers to those detergents that contain only small amounts, previously less than 5%, and even more preferably less than about 1% water. Especially preferred are substantially anhydrous detergents. Although water systems have some desirable characteristics, such as easy accessibility and low cost, water-containing detergents are often aggressive towards one or more substrate materials. In addition, substrates that are washed with water-based systems are difficult to dry. Thus, the use of water-based detergents has the dangerous characteristic that it is potentially harmful to the substrate to be cleaned and / or to its components and makes it possible to obtain substrates that are difficult to dry. Accordingly, the use of detergents or detergent compositions containing water is not preferred.

 On the other hand, in the practice of the present invention, water can be used as a solvating substance because water is capable of dissolving many types of impurities, including, in particular, inorganic impurities. Water can be used as a solvating agent alone or in combination with one or more other solvating agents. It can be particularly advantageously used in compositions containing immiscible components.

 Excellent results have been obtained for many cleaning cases in which the solvating and washing substances described above were used. However, there may be applications where improvement in purification can be realized by the use of a surfactant (s). Suitable surfactants may be selected based on prior art knowledge.

 Many techniques are available and known to those skilled in the art for performing the contacting steps of the present invention, and the use of all such technologies is within its scope. Thus, as a rule, it is sufficient that the contacting steps of the present invention are carried out under conditions sufficient to achieve the goal of each stage. That is, the step of contacting the substrate with the solvating agent is preferably carried out under conditions sufficient to solvate or release a predefined type and amount of adhesive contamination from the substrate, while the step of contacting the substrate with a detergent is previously performed under conditions sufficient to wash off a certain amount solvating substance from the substrate. For example, it appears that the step of contacting the substrate with the solvating agent may include brushing or spraying the solvating agent onto the substrate until a predetermined degree of solvation and / or release is achieved. However, Applicants have found that, in accordance with the preferred contacting conditions described below, a certain and advantageous purification is achieved.

 In general, it is preferred that the contacting steps of the present invention comprise immersing the substrate in a liquid or vapors containing a solvating agent and / or a washing substance. In addition, shaking the substrate and / or mixing the contact medium is also necessary to ensure maximum contact efficiency. In fact, maintaining relative motion between the composition and the substrate tends to accelerate the removal of contamination. In use, it is highly recommended, and thus particularly preferred, that the composition containing immiscible liquids is mixed. Mixing the immiscible liquid constituents of the composition leads to the formation of their mixture and causes the detergent to mix towards the surface of the heated composition, where it evaporates. The composition in this case tends to boil more uniformly. Upon completion of the cleaning process, including completion of mixing of the composition, immiscible liquids are easily separated into two different layers when the composition is cooled below the boiling point of the detergent. The contamination removed from the workpiece is typically collected in a layer of solvating agent. In this way, detergent contamination can be avoided.

 In practice, the system also cannot have an ignition temperature, even if it operates at a temperature higher than the ignition of a high-boiling substance. This will be the case since a lower boiling substance that does not have a flash point can be selected and, during operation, the lower boiling substance will fill the device system with a non-flammable vapor phase.

 Regarding the sequence of steps of contacting, it seems that the step of contacting the substrate with a detergent can be performed essentially simultaneously and / or sequentially with the step of contacting the substrate with a solvating liquid substance, and in accordance with some embodiments, serial contacting is preferred.

 The duration of contacting in accordance with the present invention can also vary widely depending on a number of factors, for example, the type and nature of the adhesive contamination, the materials of the substrate structure and the degree of cleaning required, and all these durations are within the scope of the present invention. However, it is preferable that the step of contacting the substrate with the solvating agent comprises maintaining the substrate in contact with the solvating agent for a time sufficient to solvate or at least release substantially all of the adhesive contamination from the substrate. It appears that a person skilled in the art having the usual qualifications, guided by the present description, can easily determine sufficient contact time for any particular application without undue experimentation. However, it is particularly preferred that the substrate is contacted with the solvating agent for a period of from about 30 seconds to about 5 minutes, and even more preferably from about 30 seconds to about 2 minutes.

 The step of contacting the substrate with the detergent preferably comprises contacting the substrate with the detergent for a period of time sufficient to wash away the main part, and preferably the entire solvating substance, from the substrate. And in this case, it seems that a specialist in this field of technology, with an average qualification, when guiding the description of this application, it is easy to determine the exact contact time required for any particular application, without resorting to excessive experimentation. However, it is generally preferred that the substrate is in contact with the detergent for a period of from about 30 seconds to about 5 minutes, and even more preferably from about 30 seconds to about 3 minutes.

 The use of contacting steps in accordance with the duration periods described above is particularly preferred for methods designed to remove rosin solder fluxes from printed circuit boards, especially for methods that use a detergent containing chlorofluorocarbons, chlorofluorocarbons, fluorocarbons or alcohols, and a solvating substance containing terpene or terpene-based material, or ether or ether-based material, for example, monobasic or dibasic acid esters, wherein uyuschee substance is preferred.

The temperature and pressure conditions under which the contacting steps are carried out can also vary widely depending on numerous factors, for example, the cost and availability of heating and cooling media, and all these changes are within the scope of the present invention. For simplicity, it is generally preferred that the contacting steps are carried out at a pressure approximately equal to the ambient pressure. Regarding temperature conditions, it is highly preferred that the step of contacting the substrate with the solvating agent comprises: (1) providing a solvating agent at a temperature of from about 10 ^° C (about 50 ^° F) to about 150 ^° C (about 300 ^° F) and even more preferably from about 30 ^° C (about 80 ^° F) to about 120 ^° C (about 250 ^° F); and (2) contacting the substrate with a solvating agent. It is also preferred that the present invention comprises contacting the substrate with a boiling liquid containing a solvating agent, especially when such boiling occurs within the temperature ranges described above.

In accordance with one preferred embodiment of the present invention, the step of contacting the substrate with the detergent comprises contacting the substrate with vapors containing the detergent, the temperature of the substrate being less than about the temperature of the vapors, preferably at least about 5 ^° C. In addition, it is preferred that the step of contacting the substrate with the detergent contained:
(1) providing a detergent at a temperature of from about 5 ^o C (about 40 ^o F) to about 120 ^o C (about 250 ^o F) and even more preferably from about 20 ^o C (about 70 ^o F) to about 100 ^o C (about 230 ^° F; and; (2) contacting the substrate with a detergent. Applicants have found that the efficiency of the solvation and washing steps of the present invention is significantly improved when these steps are performed under the temperature conditions described above.

 Regarding the actual contacting mechanism, it seems that all known contacting technologies are suitable for use in accordance with the methods of the present invention. Thus, for liquid solvating and washing substances, the contacting step may include, for example, spraying, brushing and / or dipping the substrate, dipping being preferred. For detergents in the vapor state, the contacting step may comprise, for example, blowing the vapors of the detergent on the substrate and / or dipping the substrate into vapors of the detergent, with dipping being preferred.

 A particularly preferred embodiment of the methods comprises: (a) contacting the substrate with a boiling liquid composition containing solvating and washing substances; and (c) contacting the substrate with vapors containing a major volume of detergent and a small volume of solvate, the ratio of vapor pressure of said detergent to vapor pressure of said solvating agent being at least about 20. It has been found that this embodiment is very preferred because it allows a simplified but efficient process design. According to some embodiments, the use of a boiling liquid containing a solvating agent establishes a preferred contact between the substrate and the solvating agent at elevated temperature. In addition, providing a boiling liquid containing a solvating component with a low vapor pressure and a washing component with a high vapor pressure leads to the creation of a vapor space above the boiling liquid, which contains the detergent in the main part and only small amounts, if any, of the solvating substance . Thus, the effective exclusion of the solvating agent from the vapor space, associated with the great proximity of the boiling liquid to the vaporous detergent, makes it possible to simply design a process very efficiently. In their most preferred form, the solvating and washing substances are immiscible with each other.

 We now turn specifically to the drawing, which illustrates a batch cleaning process in accordance with one embodiment of the present invention. In the methods of the present invention in accordance with this embodiment, a cleaning tank 10 is used with a baffle having both a first section 11 and a second section 12 separated by a membrane baffle or trap 12. The first section 11 of the tank 10 is filled to the first predetermined level with a liquid of a cleaning composition 14 containing a solvating agent, and the second section 12 is filled to a second predetermined level above said first predetermined level with a liquid detergent composition 15 containing a detergent. Condensing coils 16 are provided in the vapor space above the liquids contained in the tank 10. The first section 11 of the tank 10 is equipped with heating coils 18 for introducing heat into the liquid cleaning composition, and the second section 12 of the tank 10 is equipped with cooling coils 20 for removing heat from the liquid cleaning composition . For embodiments of the type shown in the drawing, it is particularly preferred that the cleaning composition 14 contained in the first section of the tank 11 contains a solvating and washing substance, and the solvating substance is preferably more, preferably from about 50 to about 80 wt.% Liquid cleaning composition, and the detergent is preferably less, preferably from about 20 to about 40% by weight of the liquid cleansing composition. The heating element 18 is preferably controlled by raising the temperature of the liquid cleaning composition to approximately the boiling point.

 Above the fluids contained in sections 11 and 12 of the cleaning tank, there are fumes 19 which contain a detergent in accordance with the present invention. More specifically, when the temperature in the section of the tank 11 rises to the boiling point of the liquid cleaning composition 14, the detergent contained therein is preferably vaporized and fills the vapor space 19 of the cleaning tank 10. The cooling stream through the condensing coil 16 is controlled to condense about the same amount of vapor which is produced by the boiling liquid contained in the first section of the reservoir 11. Condensed liquid transfer means (not shown) transmit the condensed liquid into the second section 12 of the tank 10. The corresponding degree of cooling of the detergent contained in the second section of the tank 12 is controlled by the height of the partition or overflow trap 13. Excess liquid detergent is poured through the trap 13 and enters the first section of the tank 11, thereby replenishing it loss of detergent due to evaporation.

 Next, preferred embodiments of the methods of the present invention will be described in connection with the use of the device shown in the drawing for cleaning a printed circuit board containing residual rosin solder flux. The first step comprises contacting the contaminated printed circuit board with a solvating agent by immersing the board in the boiling liquid contained in the first section 11 of the tank 10, thereby solvating and / or releasing any residual rosin flux present on the board. The first contacting step preferably has a duration of from about 1 to about 7 minutes. The next step involves contacting the substrate with a detergent so as to wash off the solvating agent and rosin flux dissolved therein or freed from it from the circuit board. This second contacting step preferably comprises two or more sequentially the following steps: (I) contacting the printed circuit board with the detergent, exposing the board to the steam space 19 located above the fluid reservoir 10, essentially immediately upon removing the board from contact with the solvating agent; (Ii) additionally contacting the circuit board with the detergent by immersing the circuit board in the relatively cold detergent contained in the second section of the tank 10; (III) additionally contacting the printed circuit board with a detergent by immersing the circuit board in a vapor space 19 located above the liquid reservoir 10. This preferred sequence of contacting steps would seem to provide a highly efficient technology for cleaning and drying sticky contaminants.

 The contacting step (I) described above is useful because it allows the excess solvating substance and the associated contamination to be washed off the board and returned by gravity to the boiling liquid. Thus, the contamination of the washing liquid contained in section 12 of the tank 10, the solvating agent and / or the removed contamination is minimized. It appears that for some embodiments, the contacting step (I) will provide reasonably clean and dry printed circuit boards. However, with more stringent requirements, it is preferred that additional contacting steps (II) and (III) are used. Specifically, the printed circuit board is preferably removed from the vapor space above the tank section 11 and immersed in the relatively cold detergent composition contained in the tank section 12. This additional contacting step provides additional washing and also serves to cool the board, preferably to approximately the temperature of the liquid in the tank section 12 The final step in this preferred embodiment comprises removing the circuit board from the cold washing liquid and contacting of the printed circuit board again with relatively hot vapors contained in the vapor space 19. Due to the temperature period, the detergent in the vapor space will condense on the substrate, thereby providing a final washing step and a clean, dry printed circuit board.

 The following examples are illustrative and comparative, but not limiting, of the present invention. The use of examples as a comparison is not a mandatory indication that the examples represent a sequence of operations of the prior art.

Example 1. Approximately 270 wt. including detergent consisting of 1,1,1-trichloroethane, and about 630 parts by weight a salvating agent consisting of limonene was charged into a heated vessel to form a liquid cleansing composition consisting of about 70 wt.% solvating agent of limonene and about 30 wt.% detergent of 1,1,1-trichloroethane. Then, the liquid cleaning composition contained in the heated vessel was brought to a boil, while the temperature of the liquid was approximately 140 ^° C. The vapor space extending directly above the boiling liquid consisted essentially of 1,1,1-trichloroethane and only a small amount (traces) of limonene. Due to heat loss, mainly through the uninsulated wall of the vessel, the temperature of the vapor space was approximately 66 ^° C below the temperature of the boiling liquid.

 A 1 ”x 2” rectangular metal test sample with a thickness of approximately 1/16 inch was contaminated with cooling oil at approximately room temperature. The contaminated test sample was then placed in a vapor space above the boiling liquid, after which the 1,1,1-trichloroethane vapor was contacted and condensed on the test sample. The test sample was kept in the vapor space until the temperature of the test sample reached the temperature of the vapor space, which was confirmed by the termination of the formation of condensate on the test sample. The test sample was removed from the vapors, subjected to visual examination and found to be contaminated with cooling oil, which indicates that only one step of contacting the test sample with vaporous detergent is not sufficient to remove substantially all of the contaminant from the test sample.

 Then, the still contaminated test sample was contacted with the solvating substance limonene by immersing the test sample in boiling liquid for a time sufficient to solvate or release essentially all of the contamination, which was 45-60 s. Thereafter, the test sample was removed from the boiling liquid and placed in a vessel containing liquid 1,1,1-trichloroethane at approximately room temperature for a time sufficient to allow the test sample to cool to approximately room temperature, which was approximately 60 seconds. Additional contact with the detergent was then achieved by re-immersing the test sample in the vapor space directly above the boiling liquid for a time sufficient to observe the cessation of condensation on the test sample, which was approximately 40-60 seconds, thus allowing contact of the test sample with vapors consisting of essentially from 1,1,1-trichloroethane detergent. Again, the test sample was removed from the vapors and found to be substantially dry and free of contaminating cooling oil and solvating agent.

Example 2. To remove the bitumen coating applied to the wire rod, the general type device shown in the drawing was used, except that cooling coils 20 were not provided in the second section 12 of the vessel. A cleaning composition was obtained by summing approximately 270 wt. including detergent consisting of isopropanol, and about 630 parts by weight solvating substance consisting of limonene. The first section of the device was loaded with a liquid cleaning composition, and the second section with a liquid essentially consisting of isopropanol. The liquid purified composition was heated to a boil. The temperature of the boiling cleaning liquid was approximately 92 ^o C. Vapors rising from the boiling liquid were condensed and transferred to the second section of the device at a speed sufficient to maintain a sufficiently constant liquid level in both its first and second sections. The vapor space immediately above the boiling liquid contained essentially isopropanol and only minor amounts of limonene. Due to heat loss, mainly through the uninsulated wall of the vessel, the temperature of the vapor space was approximately 9 ^o below the temperature of the boiling liquid. The liquid in the second section of the tank was at a temperature of about 25-40 ^° C and contained essentially isopropanol and only small amounts (traces) of limonene.

 The wire rod was coated with bitumen and then allowed to cool to approximately room temperature. The contaminated rod was then placed in the vapor space directly above the boiling liquid for a period of time sufficient to essentially stop the vapor condensation on the rod, which was approximately 40-60 s. Then the wire rod was removed from the steam space, visually inspected and found that it remained essentially contaminated with bitumen. After that, the wire rod passed through the vapor space and was placed in a boiling liquid. The wire rod was held in boiling liquid for approximately 60 seconds. After that, it was placed in the vapor phase over a boiling liquid for a period of time sufficient to indicate the termination of condensation on the wire rod, which was approximately 40-60 s. Then the wire rod was again removed from the vapors and found that it was clean and dry.

 Example 3. Example 2 was repeated except that the contaminant was wax having a high melting point. Melted wax was dipped onto a wire rod and then allowed to cool to about room temperature. After that, the coated wire rod was placed in the vapor space directly above the boiling liquid for a period of time sufficient to allow a significant reduction in the rate of vapor condensation on the rod, which was approximately 20-30 s. After that, the wire rod was removed from the steam space, subjected to visual inspection and found that it essentially remained contaminated with wax, although the presence of softening of the wax is obvious. The wire rod was allowed to cool and then immersed in boiling liquid for about 60 s. After removal from the boiling liquid, it was found that the wire rod is essentially wax free, but moistened with a solvating agent.

 After that, a clean, but wet, wire rod was immersed in a cold liquid detergent for about 10-20 seconds. Then the rod was immersed in the vapor phase above the boiling liquid for a period of time sufficient to see the termination of condensation on the wire rod, which was approximately 40-60 s. After that, the wire rod was again removed from the vapor and found that it is clean and dry.

Example 4. To remove Boscan crude oil deposited on a wire rod, the general type device shown in the drawing was used, except that the second section of the device was not loaded with washing liquid and the condensing vapors returned directly to the boiling cleaning liquid. The first section of the device was loaded with the liquid cleaning composition of Example 2. The liquid cleaning composition was heated to boiling. The temperature of the boiling cleaning liquid was approximately 92 ^° C. Vapors rising from the boiling liquid condensed and returned to the boiling liquid. The vapor space immediately above the boiling liquid contained essentially isopropanol and only minor amounts of limonene. Due to heat loss, mainly through the uninsulated wall of the vessel, the temperature of the vapor space was approximately 17 ^° C lower than the temperature of the boiling liquid.

 The wire rod was coated with crude Boscan oil and allowed to cool to room temperature. Then, the contaminated rod was immersed in the vapor space directly above the boiling liquid for a period of time sufficient to see, essentially, the termination of the vapor condensation on the rod, which was approximately 40-60 s. Then, several drops of oil falling from a contaminated wire suspension were observed. After that, the wire rod was removed from the steam space, subjected to visual inspection and found that it remained essentially contaminated with crude oil. Then the wire rod was immersed in boiling liquid for approximately 30 s and then lifted into the vapor space directly above the boiling liquid. Then the wire rod was kept in the vapor space for a period of approximately 30 s, after which it was removed from the device and allowed to cool. The observed rod was essentially clean but slightly damp. Then the wire rod was again immersed in the vapor phase above the boiling liquid for a period of time sufficient to see the termination of condensation on the wire rod, which was approximately 40-60 s. After that, the wire rod was again removed from the vapor and found that it was dry.

Example 5. To clean the wire rod from the contamination applied to it with a polyamide resin, a device of the general type shown in the drawing was used. A cleaning solution was obtained by combining approximately 270 wt. including detergent consisting of 1,1,1-trichloroethane, and about 630 parts by weight solvating substance consisting of limonene. A liquid cleaning composition was loaded into the first section of the device, and a liquid consisting essentially of 1,1,1-trichloroethane was loaded into the second section. The liquid was heated to a boil. Vapors rising above the boiling liquid were condensed and transferred to the second section of the device at a speed sufficient to maintain a substantially constant liquid level in both the first and second sections. The temperature of the boiling liquid was approximately 118 ^° C, and the temperature of the cold liquid in the second section of the tank was approximately 25-40 ^° C. Due to heat loss, mainly through the uninsulated wall of the vessel, the temperature of the vapor space was approximately 44 ^° C lower than the temperature of the boiling liquid. The vapors directly above the boiling liquid contained essentially 1,1,1-trichloroethane and not more than a small amount of limonene.

 The wire rod was melt-dipped in a Union Camp polyamide residue called U NI-REZ 2646 and then allowed to cool to about room temperature. After that, the contaminated wire rod was placed in a vapor space above the boiling liquid, after which the 1,1,1-trichloroethane vapor was contacted with the rod and condensed on it. The wire rod was kept in the vapor space for approximately one minute and then removed. It was apparent that the contaminant was not removed from the bar, thus indicating that one step of contacting the wire rod with the vaporous detergent was not enough to remove the contaminant from the wire rod.

 After that, the still contaminated wire rod was brought into contact with the solvating substance limonene by immersing the rod in boiling liquid for a time sufficient to solvate or release essentially all the contamination, which was approximately six minutes. The wire rod was then removed from the boiling liquid and placed in a section of the device containing cold liquid 1,1,1-trichloroethane for approximately 60 seconds. Then, additional contact with the detergent was again achieved by placing the rod in the vapor space directly above the boiling liquid for a time sufficient to see a significant decrease in the rate of condensation on the rod, which was approximately 40-60 s, thus ensuring the contact of the rod with vapors consisting of essentially from 1,1,1-trichloroethane detergent. The wire rod was again removed from the vapor and found to be substantially dry and free from contamination of the resin and solvating agent.

The following group of examples (examples 6-9 inclusive) illustrates the use of compositions that are within the scope of the present invention and which include solvating and washing substances that are immiscible with each other. The detergent used in the composition of these examples is perfluorohexane (C ₆ F ₁₄ ). The following is information on the various physical properties of perfluorohexane.

Perfluorohexane Properties
The basic formula is C ₆ F ₁₄
Flash Point, ^o C - No
Normal boiling point, ^o C - 56
Pour point, ^o C - -90
The density of the liquid, 25 ^o C, g / ml - 1,68
The viscosity of the liquid, 25 ^o C, SP - 0,67
Vapor pressure, 25 ^o C, mmHg - 232
Thermal conductivity, W / cm ^o C • 10 ³ - 0.57
Specific heat, 25 ^o C, cal / g ^o C - 0.25
Heat of vapor, cal / g - 21
The coefficient of thermal expansion, 25 ^o C, ml / ml ^o CC • 10 ³ - 1.6
Surface tension, 25 ^o C, dyne / cm - 12
Water solvent, 25 ^o C, dyne / ppm - 10
Ozone Depletion Potential (ODR) - Zero
Example 6. The composition of this example consists of 50 wt.% Isopropyl myristate (solvating agent) and 50 wt.% Perfluorohexane (detergent). The individual components were loaded into a vessel that was equipped with a stirrer and heater and to which a capacitor was attached. To form a mixture, the components were mixed, the mixture was heated to boiling to ensure a constant outflow of detergent. The metal part was coated with cutting fluid for cutting and immersed for 1-2 minutes in a boiling composition that had a temperature of 138 ^o F (approximately 58 ^o C). The part was then removed from the composition and raised above the steam zone, where the parts were allowed to cool to approximately room temperature. After that, the cooled part was lowered into the vapor zone, where perfluorohexane vapors were condensed on it. The temperature of the vapor in the vapor zone was 136 ^o F, which corresponds to the boiling point of perfluorohexane. The part was maintained in a steam vapor zone for a period of 5-7 minutes, during which time the liquid ceases to condense on the part. The item was removed from the steam zone and made sure that it was clean and dry.

 Example 7. A certain amount of cooling oil was added to the composition of Example 6 so that the composition contained 15% by weight of oil (based on the total weight of the composition). The sequence of operations described in example 6 was repeated using the composition with the introduced oil. With regard to cleaning and drying, the same results were obtained as in Example 6. The temperatures of the boiling composition and the vapors were the same as those described in Example 6. Upon completion of mixing and heat input, the composition was divided into two different layers. It was found that the lower layer consisted of perfluorohexane, which has a higher specific gravity than isopropyl myristate. The perfluorohexane layer was a clear and apparently uncontaminated contaminant or purifier. The top layer of the composition contained isopropyl myristate, which had a color different from the color of the cooling oil.

 Example 8. The sequence of operations described above in examples 6 and 7 were repeated except that isopropyl myristate was replaced with methyl ester of capric acid. The results were similar to those described in examples 6 and 7.

 Example 9. The sequence of operations described above in examples 6-8 was repeated except that the composition was modified to include approximately 10 parts per million non-ionic fluoride liquid surfactant sold by 3M Company under the trademark Fluordd PC- 430 and characterized by 3M Company as fluoroaliphatic polymer esters.

 The cleaning results were the same as described in examples 6-8.

 Comparative Example 4. A detergent consisting of isopropanol was loaded into a heated vessel at approximately atmospheric pressure and brought to a boil.

 A bitumen coating was applied to the wire rod and allowed to cool to approximately room temperature. The contaminated rod was immersed in boiling liquid for approximately 60 s. After removal from the boiling liquid, it was obvious that bitumen was not removed from the rod.

Another example 12 of a practical application of the present invention involves the use of a cleaning composition consisting of “immiscible” solvating and washing substances, and which has been used in an industrial cleaning composition modified by the method described below. The cleaning composition contained 80 wt.% Solvating substances and 20 wt. % detergent. The solvating agent was a terpene-based composition which contained mainly α-limonene and which was sold by Petroferm Inc. under the brand name BIOACT 121. The detergent was perfluorohexane. The cleaning device used was electrically heated; a water cooling unit was purchased from Detrex Chemical Industries, Inc. in the form of a cleaning device using a solvent model 2D12-EW (hereinafter referred to as the "Detrix cleaning device"). The Detrix cleaning device has a compartment for holding and heating a cleaning composition comprising a solvating and detergent substance and a compartment for containing the detergent. The Detrix cleaning device is modified so that it contains a means for mixing the cleaning composition and the washing composition, which means consists of a pump that removes the cleaning composition from the bottom of the compartment in which it is contained, and which pumps the cleaning composition back into the main body through the nozzles . The compartment containing the detergent was similarly modified to achieve mixing of the main part of the detergent in the compartment containing it. Detrix's cleaning device comes equipped with a steam zone, which includes cooling coils. The Ditrix cleaning device was modified with an additional set of cooling coils, which were placed above the original coils and which were cooled to -20 ^° F using a cooling system. Additional cooling coils were used to minimize the loss of evaporation of the detergent. Obviously, the present invention can be effectively used with other types of cleaning equipment, which is industrial or which can be easily modified to meet the requirements of practical applications of the present invention.

Claims (32)

 1. A liquid cleaning composition containing a solvating agent and a washing agent, characterized in that it contains a solvating agent with a vapor pressure of not more than 8 mm Hg at room temperature, having a solvating ability of at least 10, and a washing agent with a vapor pressure at room temperature from 80 - 760 mm Hg, having an ozone depletion index of not more than 0.15, the washing agent having a higher specific gravity than the solvating agent, and the solvating agent makes up the bulk of the composition, with vapor pressure of the washing agent to the vapor pressure of the solvating agent is no less than 100 or at the boiling point of the liquid composition the vapor space over it comprises essentially a pair of scrubbing agent.  2. The composition according to claim 1, characterized in that it contains a washing and solvating agents, not miscible with each other.  3. The composition according to claim 1, characterized in that as a solvating agent it contains one or more of the following substances: terpenes, dibasic esters, dibasic esters, petroleum solvents and alkyl substituted 2-pyrrolidones.  4. The composition according to claim 1, characterized in that as a washing agent it contains fluorocarbons, fluorocarbons and / or ethers.  5. The composition according to claim 1, characterized in that it contains perfluorohexene as a washing agent, and terpene and / or monobasic acid ester as a solvating agent.  6. The composition according to claim 1, characterized in that it contains a washing and solvating agents, miscible with each other.  7. The composition according to claim 1, characterized in that it contains ether as a washing agent.  8. A liquid cleansing composition containing a solvating agent and a washing agent, characterized in that as a solvating agent it contains one or more of the following substances: terpene, dibasic ester, dibasic ester, petroleum solvent, alkyl substituted 2-pyrrolidone, ketone, ether, alcohol and amine having a vapor pressure at room temperature not higher than 8 mm Hg, and as a washing agent it contains one or more of the following substances: fluorocarbon, fluorocarbon and ether having The pressure vapor at room temperature of 80 - 760 mm Hg and an ozone depletion index of not more than 0.15, the solvating agent being the main part of the composition, where the washing and solvating agents are not miscible with each other, the washing agent has a higher specific gravity than the solvating agent, and the vapor pressure ratio of the washing and solvating agent is not less than 100 and the boiling point of the composition is determined by the boiling point of the washing agent, while the vapor phase above the liquid composition at its boiling point contains mainly pa s scrubbing agent.  9. The composition of claim 8, characterized in that it contains a solvating agent in an amount of 50 to 80 wt.% And a washing agent in an amount of 20 to 40 wt. %  10. The composition of claim 8, characterized in that as a solvating agent it contains one or more of the following terpenes: alpha-pinene, beta-pinene, gamma-terpinene, delta-3-karen, limonene, dipentene and terpinolene.  11. The composition of claim 8, characterized in that it contains a monobasic acid ester as a solvating agent, and perfluorohexane as a washing agent.  12. The composition according to claim 9, characterized in that it contains a monobasic acid ester as a solvating agent and an ether as a washing agent. 13. The method of removing contaminants from the substrate, including placing and holding the substrate in a boiling liquid cleaning composition containing solvating and washing agents, removing the substrate and subsequent processing, characterized in that the solvating agent is selected with a vapor pressure at room temperature of not more than 8 mm RT. Art. and with a solvating ability of at least 10, and the washing agent is selected with a vapor pressure at room temperature of 80 - 760 mm Hg. with an ozone depletion index of not more than 0.15 and with a greater specific gravity than the solvating agent, the ratio of the vapor pressure of the washing agent to the vapor pressure of the solvating agent of at least 100 and the vapor space above the boiling composition contains mainly the vapor of the washing agent, before and after placing the substrate in a boiling cleaning composition, it is placed in the indicated vapor space, and subsequent processing is carried out by immersing the substrate in a liquid cleaning composition of the same composition a temperature below the boiling temperature at least 5 ^o C, soaking therein the substrate to align the substrate temperature and the cleaning composition, the extraction of the liquid substrate and placing it in a vapor space containing mainly couples wash agent and exposure before their condensation and removal of the substrate from vapors.  14. The method according to p. 13, characterized in that as a solvating agent choose terpene, or a dibasic acid ester, or a monobasic acid ester, or an oil solvent, or an alkyl substituted 2-pyrrolidone, or a ketone, or an ether, or an alcohol, or an amine, or a mixture of two or more of these substances, and fluorocarbon, or a fluorocarbon, or an aliphatic hydrocarbon, or an aromatic hydrocarbon, or an alcohol, or a ketone, or an ether, or a mixture of two or more of these substances, are selected as a washing agent.  15. The method according to 14, characterized in that the monobasic acid ester is selected as the solvating agent.  16. The method according to 14, characterized in that fluorocarbon is selected as the washing agent.  17. The method according to 14, characterized in that as a washing agent choose fluorocarbon.  18. The method according to clause 16, characterized in that perfluorohexane is chosen as the washing agent.  19. The method according to 14, characterized in that as the solvating agent choose ether or petroleum solvent.  20. The method according to 14, characterized in that as the washing agent choose ether.  21. The method according to 14, characterized in that the monobasic acid ester is selected as the solvating agent, and fluorocarbon is selected as the washing agent.  22. The method according to p. 14, characterized in that the monobasic acid ester is selected as the solvating agent, and fluorocarbon as the washing agent.  23. The method according to 14, characterized in that the monobasic acid ester is selected as the solvating agent, and perfluorohexane is used as the washing agent.  24. The method according to 14, characterized in that as the solvating agent choose a petroleum solvent.  25. The method according to p. 24, characterized in that as a solvating agent choose a petroleum solvent, and as a washing agent, fluorocarbon.  26. The method according to p. 24, characterized in that as the solvating agent choose a petroleum solvent, and as a washing agent fluorocarbon.  27. The method according to p. 24, characterized in that as a solvating agent choose a petroleum solvent, and as a washing agent perfluorohexane.  28. The method according to claim 20, characterized in that an ether is selected as a washing agent, and a monobasic acid ether is selected as a solvating agent.  29. The method according to claim 20, characterized in that ether is selected as a washing agent, and an oil solvent is selected as a solvating agent.  30. The method according to item 13, wherein a solvating agent with a solvating ability of at least 20 is selected, and a washing agent is selected with a vapor pressure of 80 - 680 mm Hg, with an ozone depletion rate of not more than 0.05, while the ratio of the vapor pressure of the washing agent to the vapor pressure of the solvating agent is not less than 200.  31. The method according to p. 13, characterized in that the solvating and washing agents are selected from immiscible substances.  32. The method according to p. 13, characterized in that the solvating and washing agents are selected from miscible substances.