田口實驗與CAE分析應用於FPC膠芯翹曲之研究

A Study of FPC Housing Warpage with Taguchi Methods and CAE Analysis

賴政宏(Cheng-Hung Lai)

指導教授 ： 韓麗龍

國立臺北科技大學/機電學院/製造科技研究所/碩士(2012年)

摘要

本論文研究FPC膠芯(FPC housing)在射出成形與SMT製程後之翹曲(warpage)改善，藉由Moldex3D CAE分析與實際射出成品進行比對。在不同的短射(short shot)情況或充填百分比時，CAE模擬結果與實作成品的熔膠流動波前(melt flow front)相當一致。本研究進行兩階段的田口實驗：第一階段用L8直交表，嘗試優化實驗參數的操作窗(operation window)。結果顯示在低熔膠溫度、高射出速度、高模具溫度與低保壓壓力的區間，可以有效降低迴焊後之翹曲。第二階段用L18直交表，進一步優化製程參數。結果顯示兩段射出速度、短邊肉厚增加0.03 mm，以及低保壓時間將有助於改善SMT製程後之翹曲。使用第二階段優化後的製程參數進行實驗，翹曲的平均值為0.077 mm (低於0.10 mm的要求)，證明經田口方法優化可以有效降低IR迴焊後之變形。CAE分析結果亦顯示，較高的Von Mises應力與熱應力對於迴焊後之翹曲變形有直接的影響。

關鍵字

FPC膠芯 ； 翹曲 ； 流動波前 ； 田口實驗 ； 操作窗 ； Von Mises應力

並列摘要

This thesis studies the warpage improvement of FPC housing after the injection molding and the SMT process. At different short shot or filling percentage, the melt flow fronts show no difference between Moldex3D CAE analysis and actual injection molding. This study use Taguchi methods and two stages for the experiments. First stage applied L8 orthogonal array to optimize the operation windows. Results show that at the range of low melt temperature, high injection speed, high mold temperature, and low packing pressure can reduce the deformation of reflow process. Second stage used L18 orthogonal array to optimize further the process parameters. Results the warpage can be improved when the two-stage injection speed, thickness of short side in increasing 0.03 mm, and low holding time applied. After second stage optimization,
the average warpage decreases to 0.077 mm less than the command of 0.1 mm. CAE analysis also shows that high Von Mises stress and thermal stress are directly related to the warpage after reflow.

並列關鍵字

FPC housing ； warpage ； melt flow front ； Taguchi method ； operation windows ； Von Mises residual stress

參考文獻

[1] 郭瑞昌，射出成型之結構件強度分析與品質改善，碩士論文，國立交通大學 機械工程學系，新竹，2010。

[3] Chin Chih Tai and Yung-Liang Chi, “The Influence of Processing Parameters on the Flatness for a Contact Surface of Plastic Connector”, Journal of Advanced Engineering, 2005, pp. 129-135.

[7] D.YAO,” Injection Molding High Aspect Ratio Microfeatures”, Journal of Injection Molding Technology, vol. 6, no. 1, 2002, pp. 11-17.

[18] Douven L.F.A and Baaijens F.P.T. and Meijer H.E.H., “The computation of properties of injection-moulded products”, Progress in Polymer Science, Vol. 20, no. 3, 1995, pp. 403-457.

[20] Lilia A. Sanchez and Lee E. Hornberger, Monitoring of residual stresses in injectionmolded plastics with holographic interferometry, Department of Mechanical Engineering, Santa Clara University, 2001.