A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint

Eu Poh Leng, Min Ding, Wong Tzu Ling, Nowshad Amin, Ibrahim Ahmad, Mok Yong Lee, A. S.M.A. Haseeb

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Citations (Scopus)

Abstract

Eu RoHS Directive for environmental and health concerns have resulted in significant activities to find substitutes for lead-contained solders for microelectronics. The potential candidates such as Sn-Ag 1 and Sn-Ag-Cu 1 eutectic solders with melting temperatures of 221°C and 217°C, respectively are the most prominent solders because of their excellent mechanical properties as compared with that of eutectic Sn-Pb solder2. Other candidates as drop-in replacements for eutectic Sn-Pb solder, such as Sn-In-Zn alloys, may have melting point close to 185°C, though not eutectic, and an acceptable solidification range but have received only limited attention 1. Among the many possible lead-free solder alloy candidates, three commonly used alloys to meet automotive thermal cycling requirement are Sn3.0Ag0.5Cu, Sn3.8AgO.7Cu and Sn4.0Ag0.5Cu. However, industry has found these commonly applied solder alloys to have certain level of ball drop problem which affects production yield, product quality as well as customers satisfaction. This paper reports a study which was conducted on BGA lead-free C5 solder joint system to compare SnAgNiCo solder alloy versus the conventional Sn3.8AgO.7Cu solder alloy, with the objective to strengthen the solder joint so as to eliminate ball drop encountered on the conventional Sn3.8AgO.7Cu solder alloy. This study showed that SnAgNiCo C5 solder system performed better than Sn3.8AgO.7Cu in terms of joint strength and intermetallic brittle mode failure rate. Experimental works were carried out to observe the melting properties, micro structure and elemental analysis that were obtained by Differential Scanning Calorimetry (DSC), SEM and EDX respectively. Shear and pull strength was measured by Dage which is representative of solder joint strength between the C5 solder sphere and Cu/Ni/Au pad finishing. Drop Tests were done per Tray & Packing methods to gauge solder joint performance against impact force. A comprehensive study was done to study the effect of microstructure and interface intermetallic of both solder system at ambient, high temperature storage (HTS) at 150°C for 168 hours and 504 hours, and 6× multiple reflow towards the joint integrity. Microstructure studies on SnAgNiCo solder reveals that formation of rod shape Ag 3Sn IMC distributed across the solder surface helps to act as dispersion hardening that increases the mechanical strength for the SnAgNiCo solder. Through the microstructure study with SEM, it was also found that the addition of Ni and Co into the SnAg solder alloy also helps to minimize growth of grain size and prevent increase in intermetallic thickness after thermal aging. EDX analysis confirmed that in SnAgCu solder/Ni interface, Cu-rich IMC formed on top of the Ni-rich IMC. For SnAgNiCo system, only Ni-rich IMC is found. Therefore, it is highly suspected that the presence of Cu-rich IMC posed a detrimental effect on the joint strength and tends to cause brittle joint failure. Both of the effect is then showed in ball pull result that at Time Zero after assembly and after 6× reflow, SnAgCu solder has 90% and 100% brittle mode failure, where SnAgNiCo solder has 0% and 5% for the respective read points. This result correlates with missing ball responses after packing drop tests which shows no failure for SnAgNiCo alloy. Thus, SnAgNiCo lead-free solder is a potential candidate for lead-free solder joint improvement for overall lead-free package robustness.

Original languageEnglish
Title of host publication10th Electronics Packaging Technology Conference, EPTC 2008
Pages588-594
Number of pages7
DOIs
Publication statusPublished - 01 Dec 2008
Event10th Electronics Packaging Technology Conference, EPTC 2008 - Singapore, Singapore
Duration: 09 Dec 200812 Dec 2008

Other

Other10th Electronics Packaging Technology Conference, EPTC 2008
CountrySingapore
CitySingapore
Period09/12/0812/12/08

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Soldering alloys
Strength of materials
Eutectics
Lead-free solders
Intermetallics
Microstructure
Failure modes
Melting point
Energy dispersive spectroscopy
Lead
Dispersion hardening
Scanning electron microscopy
Thermal aging
Customer satisfaction
Thermal cycling

All Science Journal Classification (ASJC) codes

  • Hardware and Architecture
  • Electrical and Electronic Engineering

Cite this

Leng, E. P., Ding, M., Ling, W. T., Amin, N., Ahmad, I., Lee, M. Y., & Haseeb, A. S. M. A. (2008). A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint. In 10th Electronics Packaging Technology Conference, EPTC 2008 (pp. 588-594). [4763497] https://doi.org/10.1109/EPTC.2008.4763497
Leng, Eu Poh ; Ding, Min ; Ling, Wong Tzu ; Amin, Nowshad ; Ahmad, Ibrahim ; Lee, Mok Yong ; Haseeb, A. S.M.A. / A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint. 10th Electronics Packaging Technology Conference, EPTC 2008. 2008. pp. 588-594
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title = "A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint",
abstract = "Eu RoHS Directive for environmental and health concerns have resulted in significant activities to find substitutes for lead-contained solders for microelectronics. The potential candidates such as Sn-Ag 1 and Sn-Ag-Cu 1 eutectic solders with melting temperatures of 221°C and 217°C, respectively are the most prominent solders because of their excellent mechanical properties as compared with that of eutectic Sn-Pb solder2. Other candidates as drop-in replacements for eutectic Sn-Pb solder, such as Sn-In-Zn alloys, may have melting point close to 185°C, though not eutectic, and an acceptable solidification range but have received only limited attention 1. Among the many possible lead-free solder alloy candidates, three commonly used alloys to meet automotive thermal cycling requirement are Sn3.0Ag0.5Cu, Sn3.8AgO.7Cu and Sn4.0Ag0.5Cu. However, industry has found these commonly applied solder alloys to have certain level of ball drop problem which affects production yield, product quality as well as customers satisfaction. This paper reports a study which was conducted on BGA lead-free C5 solder joint system to compare SnAgNiCo solder alloy versus the conventional Sn3.8AgO.7Cu solder alloy, with the objective to strengthen the solder joint so as to eliminate ball drop encountered on the conventional Sn3.8AgO.7Cu solder alloy. This study showed that SnAgNiCo C5 solder system performed better than Sn3.8AgO.7Cu in terms of joint strength and intermetallic brittle mode failure rate. Experimental works were carried out to observe the melting properties, micro structure and elemental analysis that were obtained by Differential Scanning Calorimetry (DSC), SEM and EDX respectively. Shear and pull strength was measured by Dage which is representative of solder joint strength between the C5 solder sphere and Cu/Ni/Au pad finishing. Drop Tests were done per Tray & Packing methods to gauge solder joint performance against impact force. A comprehensive study was done to study the effect of microstructure and interface intermetallic of both solder system at ambient, high temperature storage (HTS) at 150°C for 168 hours and 504 hours, and 6× multiple reflow towards the joint integrity. Microstructure studies on SnAgNiCo solder reveals that formation of rod shape Ag 3Sn IMC distributed across the solder surface helps to act as dispersion hardening that increases the mechanical strength for the SnAgNiCo solder. Through the microstructure study with SEM, it was also found that the addition of Ni and Co into the SnAg solder alloy also helps to minimize growth of grain size and prevent increase in intermetallic thickness after thermal aging. EDX analysis confirmed that in SnAgCu solder/Ni interface, Cu-rich IMC formed on top of the Ni-rich IMC. For SnAgNiCo system, only Ni-rich IMC is found. Therefore, it is highly suspected that the presence of Cu-rich IMC posed a detrimental effect on the joint strength and tends to cause brittle joint failure. Both of the effect is then showed in ball pull result that at Time Zero after assembly and after 6× reflow, SnAgCu solder has 90{\%} and 100{\%} brittle mode failure, where SnAgNiCo solder has 0{\%} and 5{\%} for the respective read points. This result correlates with missing ball responses after packing drop tests which shows no failure for SnAgNiCo alloy. Thus, SnAgNiCo lead-free solder is a potential candidate for lead-free solder joint improvement for overall lead-free package robustness.",
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Leng, EP, Ding, M, Ling, WT, Amin, N, Ahmad, I, Lee, MY & Haseeb, ASMA 2008, A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint. in 10th Electronics Packaging Technology Conference, EPTC 2008., 4763497, pp. 588-594, 10th Electronics Packaging Technology Conference, EPTC 2008, Singapore, Singapore, 09/12/08. https://doi.org/10.1109/EPTC.2008.4763497

A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint. / Leng, Eu Poh; Ding, Min; Ling, Wong Tzu; Amin, Nowshad; Ahmad, Ibrahim; Lee, Mok Yong; Haseeb, A. S.M.A.

10th Electronics Packaging Technology Conference, EPTC 2008. 2008. p. 588-594 4763497.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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AU - Amin, Nowshad

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N2 - Eu RoHS Directive for environmental and health concerns have resulted in significant activities to find substitutes for lead-contained solders for microelectronics. The potential candidates such as Sn-Ag 1 and Sn-Ag-Cu 1 eutectic solders with melting temperatures of 221°C and 217°C, respectively are the most prominent solders because of their excellent mechanical properties as compared with that of eutectic Sn-Pb solder2. Other candidates as drop-in replacements for eutectic Sn-Pb solder, such as Sn-In-Zn alloys, may have melting point close to 185°C, though not eutectic, and an acceptable solidification range but have received only limited attention 1. Among the many possible lead-free solder alloy candidates, three commonly used alloys to meet automotive thermal cycling requirement are Sn3.0Ag0.5Cu, Sn3.8AgO.7Cu and Sn4.0Ag0.5Cu. However, industry has found these commonly applied solder alloys to have certain level of ball drop problem which affects production yield, product quality as well as customers satisfaction. This paper reports a study which was conducted on BGA lead-free C5 solder joint system to compare SnAgNiCo solder alloy versus the conventional Sn3.8AgO.7Cu solder alloy, with the objective to strengthen the solder joint so as to eliminate ball drop encountered on the conventional Sn3.8AgO.7Cu solder alloy. This study showed that SnAgNiCo C5 solder system performed better than Sn3.8AgO.7Cu in terms of joint strength and intermetallic brittle mode failure rate. Experimental works were carried out to observe the melting properties, micro structure and elemental analysis that were obtained by Differential Scanning Calorimetry (DSC), SEM and EDX respectively. Shear and pull strength was measured by Dage which is representative of solder joint strength between the C5 solder sphere and Cu/Ni/Au pad finishing. Drop Tests were done per Tray & Packing methods to gauge solder joint performance against impact force. A comprehensive study was done to study the effect of microstructure and interface intermetallic of both solder system at ambient, high temperature storage (HTS) at 150°C for 168 hours and 504 hours, and 6× multiple reflow towards the joint integrity. Microstructure studies on SnAgNiCo solder reveals that formation of rod shape Ag 3Sn IMC distributed across the solder surface helps to act as dispersion hardening that increases the mechanical strength for the SnAgNiCo solder. Through the microstructure study with SEM, it was also found that the addition of Ni and Co into the SnAg solder alloy also helps to minimize growth of grain size and prevent increase in intermetallic thickness after thermal aging. EDX analysis confirmed that in SnAgCu solder/Ni interface, Cu-rich IMC formed on top of the Ni-rich IMC. For SnAgNiCo system, only Ni-rich IMC is found. Therefore, it is highly suspected that the presence of Cu-rich IMC posed a detrimental effect on the joint strength and tends to cause brittle joint failure. Both of the effect is then showed in ball pull result that at Time Zero after assembly and after 6× reflow, SnAgCu solder has 90% and 100% brittle mode failure, where SnAgNiCo solder has 0% and 5% for the respective read points. This result correlates with missing ball responses after packing drop tests which shows no failure for SnAgNiCo alloy. Thus, SnAgNiCo lead-free solder is a potential candidate for lead-free solder joint improvement for overall lead-free package robustness.

AB - Eu RoHS Directive for environmental and health concerns have resulted in significant activities to find substitutes for lead-contained solders for microelectronics. The potential candidates such as Sn-Ag 1 and Sn-Ag-Cu 1 eutectic solders with melting temperatures of 221°C and 217°C, respectively are the most prominent solders because of their excellent mechanical properties as compared with that of eutectic Sn-Pb solder2. Other candidates as drop-in replacements for eutectic Sn-Pb solder, such as Sn-In-Zn alloys, may have melting point close to 185°C, though not eutectic, and an acceptable solidification range but have received only limited attention 1. Among the many possible lead-free solder alloy candidates, three commonly used alloys to meet automotive thermal cycling requirement are Sn3.0Ag0.5Cu, Sn3.8AgO.7Cu and Sn4.0Ag0.5Cu. However, industry has found these commonly applied solder alloys to have certain level of ball drop problem which affects production yield, product quality as well as customers satisfaction. This paper reports a study which was conducted on BGA lead-free C5 solder joint system to compare SnAgNiCo solder alloy versus the conventional Sn3.8AgO.7Cu solder alloy, with the objective to strengthen the solder joint so as to eliminate ball drop encountered on the conventional Sn3.8AgO.7Cu solder alloy. This study showed that SnAgNiCo C5 solder system performed better than Sn3.8AgO.7Cu in terms of joint strength and intermetallic brittle mode failure rate. Experimental works were carried out to observe the melting properties, micro structure and elemental analysis that were obtained by Differential Scanning Calorimetry (DSC), SEM and EDX respectively. Shear and pull strength was measured by Dage which is representative of solder joint strength between the C5 solder sphere and Cu/Ni/Au pad finishing. Drop Tests were done per Tray & Packing methods to gauge solder joint performance against impact force. A comprehensive study was done to study the effect of microstructure and interface intermetallic of both solder system at ambient, high temperature storage (HTS) at 150°C for 168 hours and 504 hours, and 6× multiple reflow towards the joint integrity. Microstructure studies on SnAgNiCo solder reveals that formation of rod shape Ag 3Sn IMC distributed across the solder surface helps to act as dispersion hardening that increases the mechanical strength for the SnAgNiCo solder. Through the microstructure study with SEM, it was also found that the addition of Ni and Co into the SnAg solder alloy also helps to minimize growth of grain size and prevent increase in intermetallic thickness after thermal aging. EDX analysis confirmed that in SnAgCu solder/Ni interface, Cu-rich IMC formed on top of the Ni-rich IMC. For SnAgNiCo system, only Ni-rich IMC is found. Therefore, it is highly suspected that the presence of Cu-rich IMC posed a detrimental effect on the joint strength and tends to cause brittle joint failure. Both of the effect is then showed in ball pull result that at Time Zero after assembly and after 6× reflow, SnAgCu solder has 90% and 100% brittle mode failure, where SnAgNiCo solder has 0% and 5% for the respective read points. This result correlates with missing ball responses after packing drop tests which shows no failure for SnAgNiCo alloy. Thus, SnAgNiCo lead-free solder is a potential candidate for lead-free solder joint improvement for overall lead-free package robustness.

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Leng EP, Ding M, Ling WT, Amin N, Ahmad I, Lee MY et al. A study of SnAgNiCo vs Sn3.8AgO.7Cu C5 lead free solder alloy on mechanical strength of BGA solder joint. In 10th Electronics Packaging Technology Conference, EPTC 2008. 2008. p. 588-594. 4763497 https://doi.org/10.1109/EPTC.2008.4763497