- 期刊
Sn-9Zn-xAG無鉛銲錫合金的熱膨脹係數與熔融區間之量測研究
Measurements of Thermal Expansion Coefficients and Melting Range for Sn-9Zn-xAg Lead-free Solder Alloys
摘要
為了發展具有適當熱物性質Sn-9Zn-xAg無鉛銲朆合金，本研究的目的即在實驗量測此系列合金的熱膨脹係數(Coefficient of Thermal Expansion, CTE)與熔融區間,並探討同銀量對Sn-Zn-xAg無鉛銲朆合金之熱膨脹係數及熔融區間的影響。 本研究使用熱膨脹儀(Dilatometer)來量測Sn-9Zn-xAg合金的熱膨脹係數，實驗條件為升溫速率為5ºC/min，從40ºC升溫到120ºC。熔融區間量測實驗則是使用熱差掃瞄分析儀(Differential Scanning Calorimetry, DSC)，使用兩種升溫速率分別為5ºC/min及0.5ºC/min。 由實驗結果發現，對本系列的合金，熱膨脹係數會隨著溫度增加而增加。而溫度到達90ºC時，即不再有明顯的變化。而隨著銀含量的增加，平均熱膨脹係數會線性上升。當銀含量超過2wt%時，無鉛銲錫合金的熱膨脹係數會明顯的大於傳統鉛－錫合金，銲錫合金與基材之間熱膨脹係數差異的增加將會使產生的熱應力增大。由DSC量測實驗結果發現，銀含量在2wt%左右時，升溫曲線會出現第二個峰值，由顯微組織可觀察到鋅－銀化合物的出現，此時液相溫度會明顯的升高。根據上述結果，Sn-Zn-xAg無鉛銲錫合金從熱物性質的觀點來看，銀的含量不應超過2wt%。
並列摘要
To develop an sn-Zn-xAg lead free solder alloy with optimal thermo-physical properties, this study is conducted to experimentally investigate the effects of silver content (0-3.5wt%) on the coefficient of thermal expansion (CTE) and melting range of this particular alloy. The CTE of Sn-Zn-xAg solder alloys is measured by using a dilatometer with a heating rate of 5ºC/min from 40ºC to 120ºC. Melting range is measured by using a differential scanning calorimetry (DSC) with heating rates of 5ºC/min and 0.5ºC/min. From the test results, it is found that, for every designed solder alloys, the CTE is increased with increased temperature. When the temperature reaches 90ºC, the increase becomes less obvious. Furthermore, the CTE in the specific temperature range increases linearly with increased silver content. As the silver contents are over 2wt%, the values of CTE are greater than the conventional Sn-Pb alloy, which may generate substantial thermal stress due to the difference in CTE between solder alloy and substrate. From the results of DSC measurement, the solidus temperature is not subatantially affected by the increased silver contents in the specific silver range. However, when the silver content exceeds 2wt%, a second peak can be observed from the heating curve, which results in a substantial increase in liquidus temperature. These results are attributed to the appearance of Zn-Ag compounds, which can be observed in the microstructures. Based on the above observations, silver content should not exceed a maximum of 2wt% in order to develop an Sn-Zn-xAg lead free solder with proper thermo-physical properties.