Method for manufacturing magnetic disc substrate
A technology for disk substrates and manufacturing methods, applied in the direction of manufacturing tools, manufacturing base layers, disc carrier manufacturing, etc., can solve problems such as medium defects, and achieve the effect of reducing protrusion defects
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preparation example Construction
[0159] [Preparation Method of Polishing Liquid Composition A]
[0160] The polishing liquid composition A can be prepared by mixing, for example, alumina particles, water, and optionally silica particles, a diallylamine polymer, an oxidizing agent, an acid, and other components by a known method. In the case of mixing silica particles, they may be mixed in the state of a concentrated slurry, or may be diluted with water or the like and then mixed. As another aspect, the polishing liquid composition A can be prepared as a concentrate. The aforementioned mixing is not particularly limited, and may be performed using a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill.
[0161] [Polishing liquid composition B]
[0162] The polishing liquid composition B used in the step (2) contains silica particles from the viewpoint of reducing the penetration of alumina after the rough polishing step and the viewpoint of reducing protrusion defects after ...
Embodiment
[0223] Polishing liquid compositions A, B, and C were prepared as follows, and steps (1), (2), (3) and (4) were performed under the following conditions to polish the substrate to be polished. The results are shown in Tables 4-7. The preparation method of the polishing liquid composition, the additives used, the measurement method of each parameter, the polishing conditions (polishing method) and the evaluation method are as follows.
[0224] [Preparation of Polishing Liquid Composition A]
[0225] Alumina abrasive grains A to D shown in Table 1 below, citric acid, sulfuric acid, hydrogen peroxide, water, and colloidal silica abrasive grains b to e shown in Table 2 below and Additives A-1 to A-4 of the following Table 3 prepared a polishing liquid composition A (the following Tables 4 to 7). The contents of each component in the polishing liquid composition A other than alumina particles and silica particles are as follows: citric acid: 0.2% by weight, sulfuric acid: 0.4% by...
manufacture example 1
[0237] [Manufacture Example 1, Manufacture of Additive B-6]
[0238] Additive B-6 of the above-mentioned Table 3 was produced as follows. 180 g of isopropyl alcohol (manufactured by Kishida Chemical), 270 g of ion-exchanged water, 18 g of styrene (manufactured by Kishida Chemical), and 32 g of sodium styrene sulfonate (manufactured by Wako Pure Chemical Industries) were added to a 1 L four-necked flask, and 2, 8.9 g of 2'-azobis(2-methylpropionamidine) 2 hydrochloride (V-50, manufactured by Wako Pure Chemical Industries) was used as a reaction initiator, and polymerization was carried out at 83±2° C. for 2 hours, and further carried out for 2 hours After aging, the solvent was removed under reduced pressure, whereby Additive B-6 was obtained as a white powder. In addition, additives other than additive B-6 can use a commercial item as it is.
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