Central core for a cleaning sponge roller

#The present invention relates to a central core for a cleaning sponge roller, more specifically a central core to be attached to a cleaning sponge roller and to be used in a cleaning step in the preparation of substrates.

#In a manufacturing process of aluminum hard disks, glass disks, wafers, photo-masks or liquid crystal glass substrates, there is performed a precise polishing, so-called polishing process, using various abrasive grains such as silicon oxide, alumina and eerie in order to finish a surface of the aforementioned aluminum hard disks and so on with extremely high precision. Abrasive grains and polishing dust adhere to the surface polished in the polishing process. In order to remove them, sufficient cleaning has to be performed subsequently.

#ultrasonic cleaning and water jet cleaning are known. However, scrub cleaning with a sponge roller made of a polyvinyl acetal-based porous material is widely employed in order to achieve a high cleaning effect and to reduce damages on the substrate. Further, DI water as well as various chemicals suitable for particular substrates such as acids, alkalis and solvents is usually used as a cleaning fluid. For instance, as a cleaning fluid for silicon wafers, a mixed solution of ammonia water and aqueous hydrogen peroxide, dilute hydrofluoric acid, and a mixed solution of hydrochloric acid and aqueous hydrogen peroxide are known.

#FIGS. 1A-1D shows an example of a central core for a cleaning sponge roller of the present invention, in which FIG. 1A is a perspective view of the central core, FIG. 1B is a side view along an axial direction of the central core, FIG. 1C is a sectional view taken along X-X in FIG. 1B, and FIG. 1D is a sectional view taken along Y-Y in FIG. 1B;

#FIGS. 2A-2D shows another example of the central core for a cleaning sponge roller of the present invention, in which FIG. 2A is a perspective view of the central core, FIG. 2B is a side view along an axial direction of the central core, FIG. 2C is a sectional view taken along X-X in FIG. 2B, and FIG. 2D is a sectional view taken along Y-Y in FIG. 2B;

#FIG. 3 is a side view of an embodiment of a convex portion in which a projection in a central core for a cleaning sponge roller of the present invention has a recessed portion; and

#The present invention will be explained with reference to FIG. 1. FIG. 1 shows an example of a central core for a cleaning sponge roller of the present invention, in which FIG. 1A is a perspective view of the central core, FIG. 1B is a side view along an axial direction of the central core, FIG. 1C is a sectional view taken along X-X in FIG. 1B, and FIG. 1D is a sectional view taken along Y-Y in FIG. 1B. In FIG. 1, a central core (1) is in a hollow cylindrical shape, and has a bore (2) extending in an axial direction and a plurality of small holes (3) communicating between the bore 2 and an outer surface of the central core (1). A diameter of the bore is 5 mm to 20 mm, preferably 7 mm to 15 mm; and a diameter of the small holes is 0.5 mm to 5 mm, preferably 0.8 mm to 3 mm.

#A plurality (4 in FIG. 1) of axially elongated projections (4) are provided in a circumferential direction on the outer surface of the central core, and a transverse section of each of the projections (4), viewed from a direction perpendicular to the axial direction, has concave and convex portions (5A, 5B). When a sponge roller is set on such a central core, the convex portions (5B) of the projections (4) bite into a soft inner surface of the sponge roller to firmly hold the sponge roller. Therefore, the sponge roller is prevented from being twisted in a rotational direction (circumferential direction) and being shifted in the axial direction, which ensures uniform cleaning.

#A height between the concave and convex portions (difference in height between 5A and 5B in FIG. 1B) is preferably 0.3 to 5 mm, more preferably 0.3 to 2 mm. The projections (4) can be board-shaped ribs as shown in FIG. 1, but is not limited to this. Preferably for reinforcement, the board-shaped ribs are integrally coupled to other ribs (10) extending in a circumferential direction. The ribs (10) also serve to prevent the sponge roller from being shifted in the axial direction. The height of the projection measured at the concave portion may be appropriately set, and is preferably 1 mm to 20 mm, more preferably 2 mm to 15 mm.