應用3D視覺量測系統於SMT之錫膏體積檢測

Solder paste volume measurement using a full-field 3D machine vision system

楊俊儀(Jun-Yi Yang)

指導教授 ： 蔡篤銘

元智大學/工程學院/工業工程與管理學系/碩士(2004年)

摘要

錫膏印刷品質是表面黏著技術（SMT）製程中最重要的因子之一，因應印刷電路板上之線路及元件日趨精密，錫膏印刷的間距也變得微小，三維錫膏量測顯得日益重要，一般三維量測常使用雷射量測系統，但雷射切面需要逐點掃描，檢測時間較長，且需要昂貴的設備。本研究採用Yen與Tsai【2002】所發展之白光相位移3D量測系統於三維錫膏量測，相位移技術可對CCD取像之每一像素進行大面積之相位分析，經由相位公式計算可以快速得到物體之表面高度值，並重建物體表面輪廓圖。
本研究導入機器視覺於表面黏著技術中錫膏印刷製程後之錫膏體積量測，由於錫膏體積屬於三維量測，具有高度資訊，本研究運用相位移技術，產生高度資訊，重建錫膏3D表面輪廓。透過機器視覺瑕疵偵測於錫膏印刷後製程，及早發現瑕疵，則可以容易且經濟地清除掉印刷電路板上的錫膏印刷缺陷，避免後製程材料、人力及時間的浪費。如此不但能有效降低生產成本也使產品之良率獲得提昇。三維錫膏量測系統採用相位移技術，根據實驗結果，愈小之條紋週期可得到愈高的精確度，然而條紋週期過小亦會造成條紋對比對過低而產生雜訊。另外，為達成自動化的目的，採用將錫膏與印刷電路板基板獨立分離以計算個別錫膏的體積，可有效計算出個別錫膏的體積。

關鍵字

三維量測 ； 錫膏體積 ； 錫膏印刷檢測 ； 相位移技術

並列摘要

Quality inspection of deposited solder pastes is critical in surface mounting processes. As SMT component pitches decrease, 3D measurement of solder pastes has become more and more important. Currently, the 3D measurements for solder pastes are mainly performed by laser-based systems. However, they suffer from low inspection speed due to the physical line-scanning process. In this paper, a fast and cost-effective 3D measurement system proposed by Yen and Tsai [2002] was used for deposited solder pastes inspection. The proposed system uses an LCD-based phase shifting technique to perform full-field 3D measurement of solder pastes with high accuracy.
Potential solder joint defects in the post printing process should be detected as early as possible to reduce rework cost and improve the yield. Since the surface profile and volume measurement of the solder paste need three-dimension (3D) information, a full-field 3D machine vision system was used to obtain a sufficient number of height data points. Surface profile and volume of deposited solder pastes can be effectively and reliably calculated. Since the 3D measurement system used for solder paste inspection is based on phase shifting techniques, the relationships between the fringe period and measurement accuracy under varying inspection areas of solder pastes are thoroughly analyzed. Experimental results show that a smaller fringe period generally yields better measurement accuracy. However, when the fringe period becomes smaller, the fringe contrast will also be reduced and may result in insufficient signal-to-noise data points. The volume measurement repeatability for solder paste inspection is in the micrometer range. The processing time for an image of 640×480 pixels is less than 2 seconds on a typical personal computer.

並列關鍵字

Three-dimensional measurement ； Solder paste volume ； Printing quality inspection ； Phase shifting technique

參考文獻

葉俊吾，2002年，「運用類神經網路建構SMT錫膏印刷製程品質管制系統」，碩士論文，成功大學製造工程研究所。

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