METHOD FOR INSPECTING PENETRATION HOLE

PROBLEM TO BE SOLVED: To provide a method for efficiently inspecting presence/absence of a crack of a penetration hole.SOLUTION: A method comprises: a step S110 for preparing a glass substrate which is an object to be inspected; a step S120 for acquiring images of respective penetration holes of the glass substrate; a step S130 for calculating an apparent diameter D of each penetration hole; a step S140 for creating a frequency distribution indicating a relationship between the apparent diameter D and frequency I, drawing a horizontal line L1 indicating predetermined frequency Ion the frequency distribution, then determining the diameter D closest to a maximum frequency value Dand larger than the maximum frequency value Din which maximum frequency Iis acquired, as a threshold D, of cross points between the horizontal line L1 and the frequency distribution, in which the predetermined frequency Iis selected from a range of 0.01-0.1% of the maximum frequency I; and a step S150 for selecting the respective penetration holes whose diameter D is equal to or more than the threshold Das penetration holes which are objects to be inspected, and evaluating presence/absence of a crack on the penetration holes which are the object to be inspected.SELECTED DRAWING: Figure 1 【課題】効率的に貫通孔のクラックの有無を検査する方法を提供する。【解決手段】被検査対象となるガラス基板を準備するステップＳ１１０と、ガラス基板の各貫通孔の画像を取得するステップＳ１２０と、画像から、各貫通孔の見かけの直径Ｄを算出するステップＳ１３０と、見かけの直径Ｄと頻度Ｉの関係を示す度数分布を作成し、度数分布の上に、所定の頻度Ｉｓを表す水平直線Ｌ１を引き、水平直線Ｌ１と前記度数分布との交点のうち、最大頻度Ｉｍａｘが得られる最頻値Ｄｐよりも大きく最頻値Ｄｐに最も近い前記直径Ｄを、閾値Ｄｔとして求めるステップであって、所定の頻度Ｉｓは、最大頻度Ｉｍａｘの０．０１％〜０．１％の範囲から選定されるステップＳ１４０と、直径Ｄが閾値Ｄｔ以上である各貫通孔を検査対象貫通孔として選定し、査対象貫通孔においてクラックの有無を評価するステップＳ１５０と、を有する。【選択図】図１