Effect of Isothermal Aging on the Growth and Morphology of the Intermetallic Compounds Formed at the Solder/Cu Interface of the Lead - Free Solder Joint

2007 ◽  
Vol 561-565 ◽  
pp. 2115-2118
Author(s):  
Yun Fu ◽  
Qi Zhang ◽  
Feng Sun ◽  
Hao Yu Bai
Keyword(s):  
Solder Joint ◽  
Intermetallic Compounds ◽  
Aging Time ◽  
Isothermal Aging ◽  
Lead Free ◽  
Intermetallic Compound Layer ◽  
Lead Free Solder ◽  
Cu Substrate ◽  
Cu6sn5 Layer ◽  
Free Solder

The growth and morphology of the intermetallic compounds (IMC) formed at the interface between the solder ( Sn–3.5Ag–0.5Cu ) and the Cu substrate of the lead - free solder joint have been investigated by means of isothermal aging at 125°C. The scalloped Cu6Sn5 intermetallic compound layer was formed at the interface between the solder and Cu substrate upon reflow. The thickness of Cu6Sn5 layer increased with aging time. Cu3Sn appeared between Cu6Sn5 layer and Cu substrate when isothermally aged for 100 hours. Compare to Cu6Sn5 , the thickness of Cu3Sn was rather low, and nearly did not increase with aging time. In this paper, the comparison was made among the Sn-Pb and the Sn-Ag-Cu(SAC) solders which were pre-treated differently before soldering.

IMC Growth Mechanisms of SAC305 Lead-Free Solder on Different Surface Finishes and Their Effects on Solder Joint Reliability of FCBGA Packages

2009 ◽  
Vol 6 (2) ◽  
pp. 119-124 ◽  
Author(s):  
Sang Ha Kim ◽  
Hiroshi Tabuchi ◽  
Chika Kakegawa ◽  
Han Park
Keyword(s):  
Solder Joint ◽  
Isothermal Aging ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Surface Finishes ◽  
Cu3sn Layer ◽  
Cu6sn5 Layer ◽  
Free Solder

Intermetallic compound (IMC) growth behavior of lead-free solder plays an important role in ball grid array (BGA) solder joint reliability for flip chip BGA (FCBGA) packaging applications. The growth mechanism of IMC is reported based on a diffusion model. Thermal treatment such as accelerated thermal cycling (ATC) and isothermal aging exposure also contribute to the growth rate and morphology of lead-free solder IMC. Among the lead-free solder alloys, Sn-3.0wt.%Ag-0.5wt.%Cu (SAC305) solder is a promising substitute for Sn-Pb because of its good mechanical properties and wettability with current surface finishes. After thermal exposure, BGA solder joint reliability is degraded due to IMC formation and growth. In this study, two different thermal treatments, ATC and isothermal aging, and two different pad surface finishes, solder on pad (SOP) and electroless Ni immersion gold (ENIG), are considered in terms of IMC growth rate and mechanical solder joint reliability. An SOP finished interface forms a thin ε-phase Cu3Sn layer and a scallop-like η-phase Cu6Sn5 layer. In contrast, the ENIG finished interface forms a thick (Cu,Ni)6Sn5 IMC layer and prevents overall IMC growth. Different surface finished test vehicles are evaluated in an ATC test in a 0°C to 100°C temperature range and the Ni diffusion layer shows a longer solder joint fatigue lifetime than the nondiffusion barrier interface based on the micro cross-section and dye penetration analysis results. In an isothermal aging test at 100°C and 150°C, the aging temperature and time are valid factors to decide mechanical shock reliability. Interfacial fractures are found in the 100°C aged test vehicle due to easier crack propagation at the interface between the thin Cu3Sn layer and the scallop-like Cu6Sn5 layer based on SEM microstructure analysis results. Finally, this investigation proposes how to improve solder joint reliability and prevent interfacial fracture for SAC305 lead-free application.

Intermetallic compounds growth between Sn–3.5Ag lead-free solder and Cu substrate by dipping method

2005 ◽  
Vol 392 (1-2) ◽  
pp. 192-199 ◽  
Author(s):  
D.Q. Yu ◽  
C.M.L. Wu ◽  
C.M.T. Law ◽  
L. Wang ◽  
J.K.L. Lai
Keyword(s):  
Intermetallic Compounds ◽  
Lead Free ◽  
Lead Free Solder ◽  
Cu Substrate ◽  
Free Solder

Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

2015 ◽  
Vol 830-831 ◽  
pp. 265-269
Author(s):  
Satyanarayan ◽  
K.N. Prabhu
Keyword(s):  
Solder Joint ◽  
Solder Matrix ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Cu Substrate ◽  
Cu Substrates ◽  
Free Solder ◽  
Substrate Surfaces ◽  
Lead Free Solders

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

A Study on Reliability of Pillar-Shaped Intermetallic Compounds Dispersed Lead-Free Solder Joint

2018 ◽  
Vol 941 ◽  
pp. 2087-2092
Author(s):  
Yusuke Nakata ◽  
Motoki Kurasawa ◽  
Tomihito Hashimoto ◽  
Kenji Miki ◽  
Ikuo Shohji
Keyword(s):  
Solder Joint ◽  
Intermetallic Compounds ◽  
Thermal Cycle ◽  
The Other ◽  
Lead Free ◽  
Lead Free Solder ◽  
Large Area ◽  
Longitudinal Elastic Modulus ◽  
Free Solder ◽  
The Ideal

A pillar shaped intermetallic compounds (IMCs) dispersed solder joint is a highly durable joint to achieve large area joining. The aim of this study is to investigate the ideal dispersion amount of pillar shaped IMCs. The dispersion rate of pillar shaped IMCs depend on the joining temperature. Pillar shaped IMCs dispersion rates are 3.5% and 5.5% when the joining temperature are 300 °C and 330 °C, respectively. Longitudinal elastic modulus are improved by forming pillar shaped IMCs. As a result of examination of the durability by the thermal cycle test, the durability of the joint with the dispersion rate of 3.5% was similar to that without pillar shaped IMCs, while that with the dispersion rate of 5.5% was remarkably improved. In the case of the dispersion rate of 3.5%, pillar shaped IMCs unevenly distributed and cracks tend to progress. On the other hand, in the case of the dispersion rate of 5.5%, pillar shaped IMCs were uniformly dispersed throughout the joint and suppressed crack propagation. Comparison of durability between pillar shaped IMCs solder and indium added solder to verify the effect of pillar shaped IMCs demonstrated that pillar shaped IMCs solder were more durable than indium added solder.

scholarly journals Effect of Isothermal Aging 2000 Hours on Intermetallics Formed between Ni-Pd-Au with Sn-4Ag-0.5Cu Solders

2013 ◽  
Vol 650 ◽  
pp. 194-199 ◽  
Author(s):  
M.A. Azmah Hanim ◽  
A. Ourdjini ◽  
I. Siti Rabiatul Aisha ◽  
O. Saliza Azlina
Keyword(s):  
Aging Time ◽  
Isothermal Aging ◽  
Growth Process ◽  
Electroless Nickel ◽  
Gold Surface ◽  
Lead Free ◽  
Lead Free Solder ◽  
Reflow Process ◽  
Dense Structure ◽  
Free Solder

The present study investigated the effect of isothermal aging up to 2000 hours on the intermetallics formed between Sn-4Ag-0.5Cu lead free solder on electroless nickel electroless palladium immersion gold surface finish (Ni-Pd-Au). For all parameters, aging have an effect of changing the intermetallic morphology to coarser and dense structure. The intermetallic compound formed for the interconnection of the lead free solder changes with increased aging time from (Cu,Ni)6Sn5 compound to (Ni,Cu)3Sn4. At the end of the 2000 hours aging time, it changes to Ni3Sn4. This is the effect of Cu element availability during the intermetallics growth process. Starting from as reflow process, (Pd, Ni)Sn4 intermetallics formed near the interface of the solder joint. The formation of the (Pd, Ni)Sn4 intermetallics act like a diffusion barrier to slow down the growth of interface intermetallics. Lastly, Au element was detected in the Pd-Sn based intermetallic after aging more than 1000 hours.

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