熱效應對軟性印刷電路板壓合過程的影響研究

Abstract

脈衝加熱回流焊接(Pulse heated reflow soldering)是一種將兩個預先上好銲錫和助銲劑的零件加熱，並加熱達一適當溫度使錫熔化和流動進而凝固，而在零件與銲錫間形成一個永久性的機械性連接的技術。通常用來作為連接材料的有錫或是異方性導電膠，使用於FPC to PCB；TCP(Tape carrier Package) to PCB；PCB to COF(Chip on Film)；;FPC to□FPC。 本文以軟性印刷電路板對軟性印刷電路板以脈衝式對接技術做探討，並主要以無鉛錫為熔接之材料為主，旨在探討最佳接合之拉力其最佳參數組合，此部份以田口實驗計劃法求得最佳參數配方。 另外，為了解各層溫度之分佈，以使吾人能正確設定熱壓頭之溫度，期能預測兩片FPC中央錫之溫度是否達到熔點。故針對各層之溫度分佈，以熱電偶(Thermocouple)放置於兩片FPC底層，並測其溫度值為一邊界條件，而所施於予熱壓頭之溫度為另一邊界條件，進而求的各層之溫度分佈。此部份之溫度模擬以ANSYS作為模擬。 研究發現，代入田口實驗法之最佳參數與現行參數條件比較其損失比率，發現有5.15db的利益。利用PQL 公式 ，得PQL= 30.55%。故知，利用最佳參數條件可使品質損失成為現行參數條件的30.55%。 經ANSYS有限元素法之分析可得知以不同熱壓頭所設定之溫度參數在重熔4sec之時間裡所求得之各節點亦即各層溫度分析，並求得其對應之熱壓頭設定之參數對應到錫熔之溫度，此可方便在設定熱壓頭溫度時，正確預估錫所達之溫度是否已達熔點與否之依據。 最後之結論說明在整個Hot bar soldering製程之設計及應用做一總結說明，包括溢錫區設計、溫度設定、熱壓頭大小、FPC PAD的設計、材質表面處理以及FPC材質使用建議等項目。

Pulse heated reflow soldering is a process where two pre-fluxed，solder coated parts are heated to a temperature sufficient to cause the solder to melt，flow，and solidify，forming a permanent electro-mechanical bond between the parts and solder。General materials for connecting both of parts have Tin or ACF(Adhesive Conductive Film)，the application field used on FPC to PCB；TCP(Tape carrier package) to PCB；PCB to□COF(Chip on film)；FPC to□FPC。 This thesis mainly focuses on the FPC vs. FPC connection technique ,and use Leadfree Tin as basis melted material，our purpose is that we want to get the best conditions about pulled force for both of FPC and FPC.The study method of best conditions is found out by Taguchi method。 Furthermore ,we also hope to know what temperature distributions for those FPC layer,to let us able to setup a right temperature of hot bar head，and forecast the Tin’s temperature where is located between FPC。We apply thermocouple to measure its temperature at the bottom two pieces FPC as one boundary condition，the other boundary condition is the temperature of hot bar head 。We can use ANSYS to simulate the temperature distributions by the two items of boundary conditions. After our findings，according to Taguchi method whose loss formula find to get 5.15db advantage if we use best conditions。By the PQL formula,it will have less loss about 30.55% in best conditions process than original old process.。 By ANSYS finite analysis knows，when we set different temperature of hot bar head during the 4 sec reflow process，we can get the every node temperature；that is the temperature regarding every layer。Furthermore，we can know whether the tin already achieves to melted point，it is convenient for us to be a basic criteria for setup correct temperature of hot bar head。 Final conclusions are that we listed all of process design and application about hot bar，including over tin area design、temperature setup、the size of hot bar head、FPC pad design、material surface treatment and FPC material usage suggestions。