| 摘要 |
PROBLEM TO BE SOLVED: To improve corrosion resistance of a drill screw for fastening an exterior material with a substrate material. SOLUTION: This screw comprises a screw body 3 having a head part 5 and a drill part 9, a cap 6 for covering the head of the screw body 3, and a washer 7 and a packing 8 engaging with an under neck part of the screw body 3. An electrically nonconduct insulation layer 12 is formed in at least a part of the screw body 3 contacting with the exterior material 1 and the substrate material 2. The insulation layer 12 prevents electrolytic corrosion caused by conduction between the screw body 3 and the exterior material 1 and between the screw body 3 and the substrate material 2, and therefore high corrosion resistance can be secured.
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