具多重反應值製程之要因分析－以電路板塑料方型扁平式封裝為例

Finding the Key Factors for the Multiple-Response Manufacturing Process-Using a Solder Paste Stencil Printing Process as an Example

潘浙楠(Jeh-Nan Pan) ； 程紀嘉(Ji-Ja Chen)

《品質學報》 14卷4期 (2007/12) Pp. 435-455

摘要

工業界在進行各種品質改善的專案計畫與實務案例中，許多問題均牽涉到多個彼此相關反應值的要因分析。以本研究所探討之電路板塑料方型扁平式封裝(QFP)焊接製程為例，此種印刷電路板的焊接製程有四個彼此相關之品質特性，即焊接體積(deposited volume)、面積、高度及焊接材料投入∕產出的轉換比(transfer ratio)。Pan et al. (2004)在電路板QFP焊接製程的要因探討一文中曾針對焊接體積及投入∕產出轉換比之反應值，分別以全因子實驗(full factorial)方式進行模板厚度(stencil thickness)、焊接材料(solder paste type)、板之處理方式(board finish)、輸送帶速度(print speed)、模板孔徑大小(aperture size)及孔徑形狀(aperture shape)等六個製程參數的變異數分析，並找出影響QFP製程的重要因子。
由於上述QFP焊接製程中焊接體積、面積、高度及焊接材料投入∕產出轉換比等四個反應值彼此相關，且並非皆服從常態分配，若僅以個別反應值分別探討其影響要因的方式並不妥當，故本研究採用馬式距離結合田口系統之MTS(Mahalanobis-Taguchi system)及MTGS (Mahalanobis-Taguchi-Gram-Schmidt system)等多變量分析之手法，先將此種多重品質特性製程的反應值正交化，再利用馬氏距離的信躁比(signal to noise ratio)尋找要因。並將上述四種反應值y(下標 i)轉換成爲希求度函數(desirability function， d(下標 i))後，利用其總希求度函數進行製程之最佳化。以期建立一種透過MTS/MTGS及希求度函數方式分析多重反應值製程要因的手法。最後本研究將此分析手法與傳統田口方法進行模擬及比較分析，結果顯示本研究所提出之方法較田口方法更能正確判斷出要因。

關鍵字

多重反應值製程 ； QFP焊接製程 ； 馬式距離 ； 希求度函數 ； 田口方法

並列摘要

Multiple-input (factors) and multiple-output (response) problem has been frequently encountered and discussed in many quality improvement projects and case studies. For example, there are four correlated quality characteristics in the solder paste stencil process, i.e. the volume, area and height of solder paste deposited, which can be measured by an inline fully automatic laser-based 3-D solder paste inspection system.
In addition, transfer ratio is another response variable used in the key factor analysis of solder paste stencil printing for quad flat package (QFP) and ball grid array (BGA) package. Pan et al. (2004) conducted an experiment to determine which are the critical variables (factors) that control the amount of solder paste deposited and transfer ratio. Six factors selected in his study are stencil thickness, aperture size, aperture shape, board finish, solder paste type, and print speed. In this paper, an integrated approach of using the desirability function in conjunction with Mahalanobis-Taguchi-Gram Schmit system (MTGS) method to find and optimize the key factors for a multiple-response manufacturing process is proposed. The aim of using the MTGS method is to standardize and orthogonalize the multiple-responses so that the Mahalanobis distance for each run can be calculated and the multi-normal assumption for the correlated responses can be relieved. A realistic example of the solder paste stencil printing process is then used to demonstrate the usefulness of our proposed approach in a practical application. Finally, the simulation results show that our proposed method is more accurate than Taguchi method in searching out the key factors.

並列關鍵字

Multiple-response process ； QFP/BGA solder paste printing process ； Mahalonobis distance ； Desirability function ； Taguchi method

參考文獻

潘浙楠、李婉瑜(2006)。修正型損失函數在制定經濟工程規格上之應用研究。品質學報。13，241-256。

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Pan, J.,Tonkay, G. L.,Storer, R. H.,Sallade, R. M.,Leandri, D. J.(2004).Critical variable of solder paste stencil printing for micro-BGA and fine-pitch QFP.IEEE Transactions on Electronics Manufacturing.27,125-132.