A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier
碩士 === 國立中正大學 === 化學工程研究所 === 101 === Electromigration has become a serious reliability issue in flip chip packaging. Therefore, electromigration on interfacial reactions between electroless Ni-P or electroless Co-P and Sn-based solders was studied in this study. The reaction couples are prepared fo...
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ndltd-TW-101CCU000630432015-10-13T22:24:05Z http://ndltd.ncl.edu.tw/handle/70849361453131724165 A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier 無鉛銲點之電遷移研究-以無電鍍鎳及無電鍍鈷為擴散阻障層 Chun-Chieh,Wen 溫俊傑 碩士 國立中正大學 化學工程研究所 101 Electromigration has become a serious reliability issue in flip chip packaging. Therefore, electromigration on interfacial reactions between electroless Ni-P or electroless Co-P and Sn-based solders was studied in this study. The reaction couples are prepared for Sn-based solders/Ni-P or Co-P/Cu/Ni-P or Co-P/Sn-based solders, which have two advantages better than real flip chip solder joints. The first is that the current distribution in the structure is uniform; the second is that the nonsymmetrical Joule heating effect can be avoided. Using Ni-P alloy as barrier layer in electric current test (current density is set at 5000A/cm2 under 180oC), the result shows that layered structure IMCs is always formed at the cathode interface (electron current flows from solder layer to Ni-P). In the contrast, massive amount of IMC spall into the solder at the anode interface (electron current flows from Ni-P to solder), and two stage phase transformation is observed for Ni-P layer. It is first transformed into P-rich nickel layer due to the diffusion of nickel atoms, and then the P-rich nickel layer reacts with Sn-based solder to form Ni2SnP. TEM image shows that the layers in P-rich nickel are composed of different Ni-P IMCs, and the difference of electric current direction cause the formation of different phase. When increasing the amount of P in deposition layer, P-rich nickel layer is formed rapidly and causes the failing of diffusion barrier. On the other hand, using Co-P (4.5wt%P) alloy as barrier layer in Sn solder and conduct electric current test. The result shows that CoSn4 metastable phase is formed at the interface of both electrodes; CoSn4 is then transforms into CoSn3 when the barrier layer is completely comsumed. The rapid growth of CoSn4 is also observed under high current density. Sn-Ag-Cu alloy solder is used to react with Co-P alloy, the formation of (Cu,Co)6Sn5 phase is observed at the interface, the result shows that this phase can reduce the consuming speed of Co-P alloy in electric current test. Chao-hong,Wang 王朝弘 2013 學位論文 ; thesis 248 zh-TW |
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碩士 === 國立中正大學 === 化學工程研究所 === 101 === Electromigration has become a serious reliability issue in flip chip packaging. Therefore, electromigration on interfacial reactions between electroless Ni-P or electroless Co-P and Sn-based solders was studied in this study. The reaction couples are prepared for Sn-based solders/Ni-P or Co-P/Cu/Ni-P or Co-P/Sn-based solders, which have two advantages better than real flip chip solder joints. The first is that the current distribution in the structure is uniform; the second is that the nonsymmetrical Joule heating effect can be avoided.
Using Ni-P alloy as barrier layer in electric current test (current density is set at 5000A/cm2 under 180oC), the result shows that layered structure IMCs is always formed at the cathode interface (electron current flows from solder layer to Ni-P). In the contrast, massive amount of IMC spall into the solder at the anode interface (electron current flows from Ni-P to solder), and two stage phase transformation is observed for Ni-P layer. It is first transformed into P-rich nickel layer due to the diffusion of nickel atoms, and then the P-rich nickel layer reacts with Sn-based solder to form Ni2SnP. TEM image shows that the layers in P-rich nickel are composed of different Ni-P IMCs, and the difference of electric current direction cause the formation of different phase. When increasing the amount of P in deposition layer, P-rich nickel layer is formed rapidly and causes the failing of diffusion barrier.
On the other hand, using Co-P (4.5wt%P) alloy as barrier layer in Sn solder and conduct electric current test. The result shows that CoSn4 metastable phase is formed at the interface of both electrodes; CoSn4 is then transforms into CoSn3 when the barrier layer is completely comsumed. The rapid growth of CoSn4 is also observed under high current density. Sn-Ag-Cu alloy solder is used to react with Co-P alloy, the formation of (Cu,Co)6Sn5 phase is observed at the interface, the result shows that this phase can reduce the consuming speed of Co-P alloy in electric current test.
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author2 |
Chao-hong,Wang |
author_facet |
Chao-hong,Wang Chun-Chieh,Wen 溫俊傑 |
author |
Chun-Chieh,Wen 溫俊傑 |
spellingShingle |
Chun-Chieh,Wen 溫俊傑 A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
author_sort |
Chun-Chieh,Wen |
title |
A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
title_short |
A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
title_full |
A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
title_fullStr |
A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
title_full_unstemmed |
A Study on Electromigration in Lead-free Solder Joints-using Electroless Nickel and Electroless Cobalt as Diffusion Barrier |
title_sort |
study on electromigration in lead-free solder joints-using electroless nickel and electroless cobalt as diffusion barrier |
publishDate |
2013 |
url |
http://ndltd.ncl.edu.tw/handle/70849361453131724165 |
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