Stock material or miscellaneous articles – Hollow or container type article
Reexamination Certificate
2001-01-16
2003-12-16
Zacharia, Ramsey (Department: 1773)
Stock material or miscellaneous articles
Hollow or container type article
C428S035700, C053S396000, C206S701000, C206S720000
Reexamination Certificate
active
06663924
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a packaging material being capable of packaging a molding material such as unvulcanized kneaded composition and parts such as a sealing material for semiconductor production apparatuses in a highly clean state, and a method for packaging.
BACKGROUND ART
In manufacturing semiconductor elements, very high cleanliness is required, and the requirements for high cleanliness range over not only management of a production process of semiconductors but also semiconductor production apparatuses and parts thereof. If the parts of semiconductor production apparatuses are cleaned after built in the equipment, a degree of possible cleanliness is limited. Such parts are required to have been cleaned highly before built in the equipment.
Also cleanliness is required similarly in a molded article such as a sealing material for semiconductor production apparatuses which the present invention can be particularly suitably applied to. The present applicants have attained high cleanliness of the sealing material itself by employing a special method of cleaning the sealing material (JP-A-10-77781, JP-A-10-161988).
However unvulcanized kneaded composition and sealing materials are delivered after packaged. Therefore even if the unvulcanized kneaded composition and sealing materials are cleaned, if they are contaminated by a packaging material when or after packaged, an object of keeping them clean cannot be attained.
Hitherto low density polyethylene (LDPE) has been used widely as a packaging material for sealing materials from the viewpoint of sealing property and easy handling. However LDPE could not be made clean up to such a high cleanliness as required in the field of production of semiconductors.
Therefore the present inventors have pursued causes for contamination by a packaging material and found that in addition to a contamination by fine particles on a surface of the packaging material, a contamination derived (eluting) from a material of the packaging material is a great cause and also a contamination coming from outside environment cannot be ignored. The present inventors have made intensive studies on a packaging material and a method of packaging capable of coping with the respective causes for contamination, and thus completed the present invention.
DISCLOSURE OF INVENTION
Namely the present invention relates to the packaging material for molding materials and parts for semiconductor production apparatuses which satisfies at least one of requirements that (1) the number of fine particles having a particle size of not less than 0.2 &mgr;m and being present on the surface of the packaging material facing an article to be packaged is not more than 5,000/cm
2
, (2) a steam permeation degree at 40° C. at 90% RH is not more than 30 g/cm
2
·24 hr, (3) a total amount of gas (excepting steam) generated when heating at 80° C. for 15 minutes is not more than 5 ppm and (4) a total amount of moisture generated when heating at 80° C. for 30 minutes is not more than 13 ppm.
When the cleaned molding materials or parts for semiconductor production apparatuses are sealed in the packaging material of the present invention, allowed to stand for 24 hours in an environment of 40° C. and 90% RH and then unpacked, as compared with the cleaned molding material or parts before packaged, a percentage of an increase in the number of fine particles having a particle size of not less than 0.2 &mgr;m and being present on the surface of the molding materials or parts is not more than 150%, a percentage of an increase in an amount of moisture generated when heating the molding materials or parts at 300° C. for 30 minutes is not more than 100% and a percentage of an increase in a total amount of gas (excepting steam) generated when heating them at 200° C. for 15 minutes is not more than 100%.
BEST MODE FOR CARRYING OUT THE INVENTION
The packaging material for molding materials and parts for semiconductor production apparatuses satisfies at least one of the above-mentioned specific requirements.
First those specific requirements and measuring methods therefor are explained below.
(Specific Requirement 1) The number of fine particles having a particle size of not less than 0.2 &mgr;m and being present on the surface of the packaging material facing an article to be packaged (unvulcanized kneaded composition or parts) must be not more than 5,000/cm
2
. In case where the packaging material is a vapor deposition-treated film or sheet or a laminated material mentioned hereinafter, fine particles being present on the surface of innermost layer facing an article to be packaged should satisfy this requirement.
A measuring method is such that a sample of packaging material having a surface area of 10 cm
2
is dipped in 1,000 ml of ultra pure water, followed by vibrating for five minutes at an amplitude of 10 cm at the number of vibrations of 2 times/sec with a vibrator (TS-4 available from Taiyo Kagaku Kogyo Kabushiki Kaisha), allowing to stand for 20 minutes and then measuring the number of fine particles having a particle size of not less than 0.2 &mgr;m with a submerged particle counter (available from KABUSHIKI KAISHA LION).
The number of fine particles can be reduced, for example, by wet cleaning method of washing with a washing chemical (ultra pure water, acid, alkali, or the like), a method of spraying a high purity compressed gas, or the like method. The less the fine particles are, the better. The number of fine particles is preferably not more than 4,000/cm
2
, more preferably not more than 3,000/cm
2
.
(Specific Requirement 2) A steam permeation degree at 40° C. at 90% RH must be not more than 30 g/cm
2
·24 hr.
A measuring method is such that according to ASTM E-96, a sample of packaging material is fixed on a moisture permeable cup in which water is put, the cup is allowed to stand for 24 hours in an air-conditioned room of 40° C. and 90% RH and then a weight reduction of water is measured.
A steam permeation degree is used for evaluation of water penetration from the outside of the packaging material. The smaller, the better. If water adheres to an article to be packaged, particularly parts for semiconductor production apparatuses, it has an adverse effect on a semiconductor production process. Examples of the packaging material satisfying such a specific requirement are, for instance, one of films of polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) and polybutylene naphthalate (PBN); olefin resins such as polypropylene (OPP), polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC); and fluorine-containing resins such as polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride(PVF), or a laminated film comprising two or more thereof. Also even such resin films as polyamide and rayon having a large degree of steam permeation can be used if the steam permeation degree is reduced by subjecting them to vapor deposition with silicon oxide, aluminum or aluminum oxide or by laminating a resin film having a small degree of steam permeation such as an aluminum foil or polyvinylidene chloride.
A steam permeation degree is preferably not more than 25 g/cm
2
·24 hr, more preferably not more than 15 g/cm
2
·24 hr.
A thickness of the film or laminated film is optionally selected so that the steam permeation degree is as mentioned above. The thickness is usually not more than 100 &mgr;m, preferably not more than 70 &mgr;m from the viewpoint of easy handling.
(Specific Requirement 3) A total amount of gas (excepting steam) generated when heating at 80° C. for 15 minutes must be not more than 5 ppm.
A measuring method is such that a sample of packaging material (1 g) is put in a seal tube and heated at 80° C. for 15 minutes. A generated gas is collected in a trap tube coole
Hasegawa Masanori
Higashino Katsuhiko
Kishine Mitsuru
Noguchi Tsuyoshi
Daiken Industries Ltd.
Zacharia Ramsey
LandOfFree
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