高阻量測系統之動態參數設計及可行性分析

隨著表面黏著元件(Surface Mount Device；SMD)的扁平化與微細化，使得印刷電路板組裝(Printed Circuit Board Assembly；PCBA)的尺寸愈漸縮小且電路佈線高密度化。由於PCB之功能密度持續增加，可能因其表面存在助焊劑殘留物(Flux Residue)，造成絕緣電阻(Surface Insulation Resistance；SIR)下降，或金屬離子發生電化學遷移(Electrochemical Migration；ECM)現象，造成漏電或是短路的失效。高阻量測系統用以測量PCB表面絕緣電阻，檢測線路間是否發生瞬間短路或出現絕緣失效的緩慢漏電之情形，而影響電子零件電氣特性，以確保產品符合安規要求。本研究建構動態參數設計，應用於高阻量測系統之測試參數最佳化。由於在SIR/ECM試驗時，絕緣阻抗值的變化範圍往往介於109~1011歐姆(Ohm)之間，故信號因子選擇涵蓋上述阻抗範圍。此外，規劃雜音因子以考量SIR/ECM測試過程所需量測之微量電流，容易受電磁波、金屬導體及操作人員等外在環境雜音對阻抗讀值的影響。得最佳測試參數水準為量測週期390毫秒/次、測試電壓100V、充電時間15秒、暫停時間100秒，提供測試人員於進行SIR/ECM測試時，系統參數設定依據。進而探討各參數設定於量測時對系統之影響：量測週期愈長、測試電壓愈高、充電時間愈長，均能使量測迴路之電流愈加穩定，俾使阻抗讀值對雜音的敏感性較低；而暫停時間對系統SN比影響最不顯著。其次，針對上述所決定之系統最佳測試參數水準，進行量測系統分析。GR&R實驗結果證實，個案中使用之量測系統本身變異甚小(0.98%)，樣本間之變異大(99.02%)，且量測能力指標( )為9.88%，落於可接受標準值10%內，表示系統具備足夠之量測能力，得以有效辨識待測物發生助焊劑殘留物解離或金屬離子發生電化學遷移現象。最後，依循業界規範IPC-TM 650 2.6.3.7，決定本個案使用之量測系統於前述最佳測試條件下之測試能量上限，該量測系統於規範時間20分鐘內，共可取得61筆有效讀值。進而探討若需增加額外測試能量，期望能在最短時間內完成製程驗證，而使用其他可行(非最佳)之測試參數下，對於系統讀值有效性之影響。結果顯示，在系統滿載測試情況下，同時達到最大SN比21.95db之理想測試參數水準為：量測週期390 毫秒/次、測試電壓100V、充電時間5秒、暫停時間100秒。

關鍵字

高阻量測系統； SIR ； ECM ；動態參數設計；量測系統分析； GR&R

並列摘要

With the surface mount device, the printed circuit board (PCB) revolves in the direction of miniaturization and high functional density. The presence of flux residues may result in decreasing surface insulation resistance (SIR) and/or occurring of metal ions electrochemical migration (ECM). These scenarios may cause circuit short failure. High resistance measuring system is to measure the SIR values of the PCB according to the safety regulations. In this study, we construct the Dynamic Parametric Design to determine the optimal test parameters for the high resistance measuring system. In SIR/ECM test, the SIR is in the range of 109 - 1011 ohms. Thus, the signal factors is with three levels, 109 ohms , 1010 ohms and 1011 ohms. While the SIR/ECM testing process involves measuring small amount of current, the noise factor considers extrinsic noise, such as electromagnetic waves, metallic conductors and operator's behaviors. The optimal test parameters are measuring cycle 390 ms, test voltage 100V, charge time 15 seconds and pause time 100 seconds. Secondly, the measurement system analysis is conducted with the optimal parameters. We confirmed that the measuring system variation is very small (0.98%) compared to the variation between sample parts (99.02%). The measuring capability index was 9.88%, which is in an acceptable range (<10%). Thus, the system has sufficient capability to effectively identify the PCBs SIR decreased and occurrence of ECM phenomenon. Finally, we found that a total of 61 efficiently values can be obtained at 20 minutes based on the industry standard IPC-TM 650 2.6.3.7 if the above mentioned optimal parameters are applied. The use of additional test capacity may impact the test effectiveness. The results show that when the system is fully loaded , the ideal test parameters are measuring cycle 390 ms/per time, test voltage 100V, charge time 5 seconds and pause time 100 seconds. The corresponding SN ratio 21.95db.

並列關鍵字

High Resistance Measuring System ； SIR ； ECM ； Dynamic Parametric Design ； Measurement System Analysis ； GR&R

參考文獻

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高阻量測系統之動態參數設計及可行性分析

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