銅導柱中不同錫銀焊錫高度之可靠度研究

Abstract

在本研究中，探討銅導柱(Cu/Ni/SnAg)中不同錫銀焊錫高度(16/19/28um-SnAg) 經過2600C多次迴焊、-65~1500C溫度循環、1500C高溫儲存及高溫、高壓、高濕(1300C,85RH%,230kPa)等可靠度測試後，觀察介金屬化合物之微結構變化，比較三種不同錫銀厚度的介金屬成長速率，並進行錫銀及銅的推力測試，觀察比較推力值及其破裂面和橫斷面(Cross-section），並探討介金屬厚度對抗剪強度(Shear strength)的影響。 經過高溫測試，隨著測試次數及時間增加，三種不同錫銀厚度的介金屬化合物厚度都增加了。以SEM觀察到的微結構剖面圖，介面間未發現破裂，裂縫，分層，孔洞產生。Cu-30μm/Ni-3μm/SnAg-28μm在2600C多次迴焊下，介金屬化合物Ni3Sn4成長速率常數為0.0792μm /reflow times，在溫度循環測試之IMC成長速率常數為7.0x10-4μm /cycle，在高溫儲存之IMC成長速率常數為6.42x10-2μm /hr1/2。 不同的錫銀焊錫高度試片，經過可靠度的測試後，雖然錫銀厚度不同，但IMC成長趨勢相同，推力測試錫銀結果，趨勢也是相同的，利用光學顯微鏡觀察錫銀剪力測試破裂面，可發現所有的破裂機構全發生在錫銀銲錫內部之延性破裂，並沒有出現任何異常的脆性破裂機構。測試其電鍍銅剪力強度，銅的推力測試結果並沒有因CuNiSnAg總體積及總高度改變而有所差異，利用光學顯微鏡觀察銅剪力測試破裂面，可發現所有的破裂機構全發生在銅破裂。

The effect of IMC thickness on shear strength for Cu/Ni/SnAg pillar bump with different SnAg solder height (16/19/28um-SnAg) after different reliability test was discussed in this study. Besides, the IMC microstructure changing, growth rate, shear strength, fracture surface and cross-section was discussed after 2600C multi reflow,-65~1500C temperature cycle test, 1500C high temperature storage and high temperature/pressure/humidity (1300C,85RH%,230kPa) test. After reliability test, no void, crack or delamination was found at interface by SEM inspection. The IMC thickness was increased with time and cycle. After 2600C multi reflow, the Ni3Sn4 growth rate was 0.0792μm /reflow times for Cu-30μm/Ni-3μm/SnAg-28μm Cu pillar bump. Besides, the Ni3Sn4 growth rate was 7.0x10-4μm /cycle & 6.42x10-2μm /hr1/2 for Cu-30μm/Ni-3μm/SnAg-28μm Cu pillar bump after temperature cycle & high temperature storage, respectively. The Ni3Sn4 growth rate was similar between different SnAg solder height sample after reliability test. The shear strength of SnAg solder was also similar and the fracture surface was in solder (ductility fracture) between different SnAg solder height sample after reliability test. The shear strength of Cu pillar was no significant difference even in different SnAg solder height sample after reliability test. The fracture surface was all in Cu by OM inspection.