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Mold cleaning sheet and manufacturing method of a semiconductor device using the sameRelated Patent Categories: Semiconductor Device Manufacturing: Process, Packaging (e.g., With Mounting, Encapsulating, Etc.) Or Treatment Of Packaged Semiconductor, Metallic Housing Or Support, And EncapsulatingMold cleaning sheet and manufacturing method of a semiconductor device using the same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060194372, Mold cleaning sheet and manufacturing method of a semiconductor device using the same. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCES [0001] This is a continuation application of U.S. Ser. No. 11/218,603, filed Sep. 9, 2005, which is a continuation application of U.S. Ser. No. 10/763,187, filed Jan. 26, 2004, (now abandoned) which is a continuation of U.S. Ser. No. 10/086,691, filed Mar. 4, 2002 (now abandoned). BACKGROUND OF THE INVENTION [0002] This invention concerns a semiconductor manufacturing technique and, more in particular, it relates to a technique effective to application for the improvement of the cleaning effect for cleaning inside a molding die for use in semiconductor devices, as well as improvement for the productivity. [0003] The technique described below has been studied by the present inventors upon study and completion of the invention and the outline is as described below. [0004] In the resin encapsulating step for resin encapsulation type semiconductor devices, since resin molding steps are repeated again and again, contaminants such as resin burrs, oxide films, oils or dusts are accumulated to an inside of a molding die in which an encapsulating resin is filled, that is, in the cavities and the runners, as well as the periphery of air vents and cull blocks of an upper die and a lower die forming a pair of molding dies. [0005] Since such contaminants give undesired effects on the quality of molding and lower the releasability upon releasing of products from the molding die, an operator has to clean the molding die on every predetermined cycles of resin shots. [0006] However, since cleaning for the molding die by the operator, being conducted by manual operation, requires a considerable period of time, a technique capable of cleaning the molding die in a short period of time has been demanded. [0007] For coping with such a demand, Japanese Patent Laid-Open Hei 1(1989)-95010 discloses a cleaning method of clamping a lead frame not mounted with a semiconductor chip (hereinafter referred to as a dummy lead frame) between main surfaces (mating surfaces) of a molding die and injecting and hardening a cleaning resin formed, for example, of a melamine resin in the molding die, thereby depositing contaminants on the surface of the cleaning resin and removing the contaminants together with the cleaning resin. [0008] Further, there is also a method of directly flowing a cleaning resin at a high pressure and a normal pressure into the cavity without using the dummy frame. [0009] However, since an expensive dummy lead frame is used for cleaning in this technique, it is not economical, and a high accuracy is necessary for positioning the molding die and the dummy lead frame since the dummy lead frame of a predetermined shape adaptable to the molding die has to be set and clamped at a predetermined position of the molding die. Further, the cleaning resin formed in the cull portions or the runner portions are separated being detached from the lead frame and it requires a considerable time to remove the separated resin from the molding die to worsen the operation efficiency. Further, the separated culls and runners are put between the sliding portions of the molding apparatus to sometimes result in disorder. [0010] In view of the above, for overcoming such problems, the techniques to be described below have also been proposed. [0011] Japanese Patent Laid-Open Hei 6(1994)-254866 discloses a method comprising the steps of clamping a sheet-like material made of a cotton fabric (non-woven fabric) capable of impregnating and permeating a cleaning resin between opened molds, and filling a cleaning resin in a molten state into the cavity of closed molding dies. [0012] As has been described above in the known literature, since a liquid cleaning resin is injected in a state where a sheet capable of impregnating and permeating a cleaning resin and a chemical is put between the main surfaces (mating surfaces) of upper and lower dies, the positioning accuracy required between the molding die and sheet can be lowered and the cleaning resin and the chemical penetrate also to portions where the sheet is put between the main surface of the upper and lower dies, thereby to conduct cleaning for the molding dies. SUMMARY OF THE INVENTION [0013] However, in the first mentioned technique, when the cleaning resin is filled in the cavity, the sheet-like member moves vertically (lift) in the cavity, by which the sheet-like member forms resistance to the flow of the cleaning resin to bring about a phenomenon that the cleaning resin does not prevail throughout the cavity. [0014] As a result, this provides a problem that contaminants remain at the corners of the cavity to make the cleaning for the inside of the cavity insufficient. [0015] The mating surface of the molding die is formed, at the corners of the outer periphery of the cavity, with concaved portions in communication therewith such as flow cavity (for receiving escaping air or encapsulating resin to the flow cavity to avoid inclusion of air from the gate or improve the balance of fillage of the encapsulating resin in the cavity) or air vents. [0016] However, in the cleaning for the molding die by using the molding die cleaning sheet, the cleaning resin less goes around to the vicinity of the corners of the cavity and, as a result, the cleaning resin does not intrude into the flow cavity or air vent during cleaning and does not clean the flow cavity or air vent and, accordingly, this results in a problem for the insufficiency in the filling of the encapsulating resin to the cavity upon molding of products after the cleaning. [0017] Further, when the encapsulating resin less goes around to the vicinity of the corners for the cavity, the cleaning resin is not entangled to the molding die cleaning sheet at portions corresponding to the vicinity of the corners for the cavity, so that the cleaning resin remains upon detaching the cleaning resin together with the molding die cleaning sheet from the mating surfaces of the molding die after the completion of the cleaning, to require much labour for the removal of the molding die cleaning sheet and the cleaning resin from the mating surfaces, and this particularly results in a problem that the cleaning resin clogs in the air vents of the upper and lower cavities in three directions except for the gates. [0018] Further, at the mating surface of a molding die for conducting molding of an SOP (Small Outline Package) having an elongate encapsulation portion or QFN (Quad Flat Non-leaded Package) using a matrix frame, when the distance between the outer end of the cavity and the edge of the mating surface is relatively short (for example, 10 mm or less), the cleaning resin leaked from the cavity goes beyond the molding die cleaning sheet upon cleaning of the molding die and deposits on the lateral surface in contiguous from the mating surface of the molding die. [0019] In such a case, it takes a long time to remove the cleaning resin deposited on the lateral side of the molding die and, as a result, this results in a problem of lowering the efficiency of the cleaning operation for the molding die. [0020] Further, as described above, the cleaning method of adsorbing the contaminants by the melamine resin results in a problem that the sufficient cleaning effect can not sometimes be obtained. [0021] This invention intends to provide a molding die cleaning sheet for improving the cleaning effect for the molding die and shortening the time for the cleaning operation thereby improving the productivity, as well as a method of a manufacturing a semiconductor device using the same. Continue reading about Mold cleaning sheet and manufacturing method of a semiconductor device using the same... Full patent description for Mold cleaning sheet and manufacturing method of a semiconductor device using the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Mold cleaning sheet and manufacturing method of a semiconductor device using the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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