Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1996-04-02
1998-08-04
Lusignan, Michael
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
134 11, 134 26, 134 29, 134 30, 134 31, 134 40, 134 952, 134113, 510475, B08B 308, B08B 310, B08B 312, C11D 3395
Patent
active
057893594
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a detergent alternative to Flon type solvents and chlorine type solvents, a method of cleaning, and an apparatus for cleaning.
BACKGROUND ART
Electronic parts such as HIC, modules, and packaged substrates, thin metallic strips such as IC, transistor grade lead frames, and hoop materials, bearings, and precision microparts, while in process of manufacture, are smeared with various kinds of smeary substances represented by water type or solvent type machining oils such as resisting agent, flux, solder paste, cutting oil, quenching oil, rolling oil, press oil, punching oil, drawing oil, assembling oil, and wire drawing oil, and dirt and dust.
The operation for the manufacture of a printed wiring board, for example, is broadly divided into a process for producing a bare board and a process for packaging IC's and electronic parts on the bare board. The printed wiring board is smeared, in the process for producing a bare board, mainly with an acid and an alkali to be used in the work of printing and the work of etching and, in the process for packaging, with the debris from solder and flux to be used in the work of soldering electronic parts. The particular smeary substances that must be removed from the smeared printed wiring board are the active agent contained in the flux and such organic salts as CuCl.sub.2 and (RCOO).sub.2 Cu which are the products of reaction between the active agent and the oxide film originating in the action of the active agent with the basis of substrate. These smeary substances are polar in quality. If they remain on the produced printed wiring board, therefore, they will absorb moisture and induce such adverse phenomena as leakage, migration, degradation of the magnitude of insulation resistance, and corrosion of pins and wires. Then, in the case of the operation of manufacture of a semiconductor, the ingress to the semiconductor of an ionic substance as an extraneous matter poses a serious problem called a "sodium panic." In the case of metallic parts obtained by machining, these smeary substances when suffered to persist entail such problems as corrosion and discoloration. These smeary substances, therefore, must be removed before the start of a next process or during the finishing process of a product.
As detergents for the removal of these smeary substances, Flon type solvents represented by Flon 113 and organic solvents such as trichloroethane, trichloroethylene, tetrachloroethylene, and carbon tetrachloride have been heretofore used extensively.
Recently, the widespread appreciation of the fact that the release of Flon type solvents into the ambient air results in the depletion of the ozonosphere and exerts a serious influence on human bodies and biotic systems has been urging the necessity for gradually tightening the restriction imposed on the use of Flon 12 and Flon 113 which have high ozone depletion coefficients and eventually totally banning the use thereof on the global scale. Further, since the chlorine type organic solvents such as trichloroethylene and tetrachloroethylene are held responsible for the environmental problem of inducing pollution of soil and ground water, the restriction imposed on their use is tending toward increasing exaction.
Under the circumstances, Flon type substances which have lower ozone depletion coefficients than the existing Flon type solvents are being developed and they have been already put to commercial production partly. These Flon type substances are not regarded as fully ideal alternative detergents, however, because they are not absolutely incapable of depleting the ozonosphere. Thus, attempts are being made to switch the Flon type detergents currently used on numerous industrial products to water, alkalis, and solvents.
The main alternative methods heretofore proposed for the cleaning of a printed wiring board include a water type cleaning method which resides in removing a water-soluble flux with purified water, a semi-water type cleaning method which comprises removing the flux with a
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Database WPI, Derwent Publications Ltd., London, GB; An 89-160476 XP002008718 & JP-A-01 101 400 (Toyota Jidosha KK), Apr. 1989 *abstract*.
Koga Mayumi
Kumagai Masaru
Nakamura Tadayuki
Saitoh Nobuhiro
Shimozawa Hiroshi
Kabushiki Kaisha Toshiba
Lusignan Michael
Toshiba Silicone Co. Ltd.
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