Investigation of mechanical shock testing of lead-free SAC solder joints in fine pitch BGA package

2008 ◽  
Vol 48 (7) ◽  
pp. 1079-1086 ◽  
Author(s):  
Y.T. Chin ◽  
P.K. Lam ◽  
H.K. Yow ◽  
T.Y. Tou
Keyword(s):  
Solder Joints ◽  
Lead Free ◽  
Mechanical Shock ◽  
Shock Testing ◽  
Fine Pitch ◽  
Bga Package ◽  
Sac Solder

Nanoindentation Measurements of the Mechanical Properties of Individual Phases Within Lead Free Solder Joints Subjected to Isothermal Aging

2018 ◽  
Author(s):  
Abdullah Fahim ◽  
Sudan Ahmed ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Bulk Solder ◽  
Lead Free ◽  
Nanoindentation Test ◽  
Lead Free Solder ◽  
Free Solder ◽  
The Individual ◽  
Sac Solder

Exposure of lead free solder joints to high temperature isothermal aging conditions leads to microstructure evolution, which mainly includes coarsening of the intermetallic (IMC) phases. In our previous work, it was found that the coarsening of IMCs led to degradation of the overall mechanical properties of the SAC solder composite consisting of β-Sn matrix and IMC particles. However, it is not known whether the isothermal aging changes properties of the individual β-Sn and IMC phases, which could also be affecting to the overall degradation of properties. In this study, the aging induced variations of the mechanical properties of the β-Sn phase, and of Sn-Cu IMC particles in SAC solder joints have been explored using nanoindentation. SAC solder joints extracted from SuperBGA (SBGA) packages were aged for different time intervals (0, 1, 5, 10 days) at T = 125 °C. Nanoindentation test samples were prepared by cross sectioning the solder joints, and then molding them in epoxy and polishing them to prepare the joint surfaces for nanoindentation. Multiple β-Sn grains were identified in joints using optical polarized microscopy and IMCs were also observed. Individual β-Sn grains and IMC particles were then indented at room temperature to measure their mechanical properties (elastic modulus and hardness) and time dependent creep deformations. Properties measured at different aging time were then compared to explore aging induced degradations of the individual phases. The properties of the individual phases did not show significant degradation. Thus, IMC coarsening is the primary reason for the degradation of bulk solder joint properties, and changes of the properties of the individual phases making up the lead free solder material are negligible.

Isothermal Aging Effects on the Mechanical Shock Performance of Lead-Free Solder Joints

2011 ◽  
Vol 1 (5) ◽  
pp. 714-721 ◽  
Author(s):  
Hongtao Ma ◽  
Tae-Kyu Lee ◽  
Dong Hyun Kim ◽  
H G Park ◽  
Sang Ha Kim ◽  
...  
Keyword(s):  
Isothermal Aging ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Mechanical Shock ◽  
Aging Effects ◽  
Free Solder

How Mitigation Techniques Affect Reliability Results for BGAs

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001992-002017
Author(s):  
Greg Caswell ◽  
Melissa Keener
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
The Other ◽  
Lead Free ◽  
Mechanical Shock ◽  
Sinusoidal Vibration ◽  
Shock Testing ◽  
Mitigation Techniques ◽  
Lead Free Solders ◽  
Mitigation Technique

Since 2006 RoHS requirements have required lead free solders to take the place of tin-lead solders in electronics. The problem is that in some environments the lead free solders are less reliable than the older tin-lead solders. One of the ways to solve this problem is to corner stake, edge bond or underfill the components. When considering what mitigation technique and material to use, the operating conditions must be characterized. The temperature range is important when selecting a material to use since the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are important properties. If improperly chosen, the mitigation material can cause more failures than an unmitigated component. This study focused on 208 I/O BGAs on a 4 layer FR4 board. There were three solders tested; two lead free (SAC305 and SN100C) and one leaded (SnPb). Three mitigation techniques were tested: corner staking, edge bonding, and underfilling. Each of these techniques had two mitigation materials tested. One material was reworkable and the other was not. The boards were subjected to mechanical shock testing and sinusoidal vibration testing until failure. The results of the testing show that no one mitigation technique is best for all of the conditions tested. The same is true for the mitigation material. The best choice of mitigation technique and material is application dependent.

Achieving high reliability low cost lead-free SAC solder joints via Mn or Ce doping

2009 ◽  
Author(s):  
Weiping Liu ◽  
Ning-Cheng Lee ◽  
Adriana Porras ◽  
Min Ding ◽  
Anthony Gallagher ◽  
...  
Keyword(s):  
Solder Joints ◽  
High Reliability ◽  
Low Cost ◽  
Lead Free ◽  
Sac Solder

Wafer Bumping, Assembly, and Reliability of Fine-Pitch Lead-Free Micro Solder Joints for 3-D IC Integration

2012 ◽  
Vol 2 (8) ◽  
pp. 1229-1238 ◽  
Author(s):  
Ching-Kuan Lee ◽  
Tao-Chih Chang ◽  
John H. Lau ◽  
Yu-Jiau Huang ◽  
Huan-Chun Fu ◽  
...  
Keyword(s):  
Solder Joints ◽  
Lead Free ◽  
Fine Pitch

How Mitigation Techniques Affect Reliability Results for BGAs

2016 ◽  
Vol 2016 (1) ◽  
pp. 000134-000138
Author(s):  
Greg Caswell ◽  
Melissa Keener (Black and Decker)
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
The Other ◽  
Lead Free ◽  
Mechanical Shock ◽  
Sinusoidal Vibration ◽  
Shock Testing ◽  
Mitigation Techniques ◽  
Lead Free Solders ◽  
Mitigation Technique

Abstract Since 2006 RoHS requirements have required lead free solders to take the place of tin-lead solders in electronics. The problem is that in some environments the lead free solders are less reliable than the older tin-lead solders. One of the ways to solve this problem is to corner stake, edge bond or underfill the components. When considering what mitigation technique and material to use, the operating conditions must be characterized. The temperature range is important when selecting a material to use since the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are important properties. If improperly chosen, the mitigation material can cause more failures than an unmitigated component. This study focused on 208 I/O BGAs on a 4 layer FR4 board. There were three solders tested; two lead free (SAC305 and SN100C) and one leaded (SnPb). Three mitigation techniques were tested: corner staking, edge bonding, and underfilling. Each of these techniques had two mitigation materials tested. One material was reworkable and the other was not. The boards were subjected to mechanical shock testing and sinusoidal vibration testing until failure. The results of the testing show that no one mitigation technique is best for all of the conditions tested. The same is true for the mitigation material. The best choice of mitigation technique and material is application dependent.

Nanomechanical Characterization of Aging Effects in Solder Joints in Microelectronic Packaging

2013 ◽  
Author(s):  
Mohammad Hasnine ◽  
Muhannad Mustafa ◽  
Jing Zou ◽  
Jeffrey C. Suhling ◽  
Barton C. Prorok ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solder Joints ◽  
Bulk Solder ◽  
Lead Free ◽  
Lead Free Solder ◽  
Aging Effects ◽  
Single Grain ◽  
Free Solder ◽  
Aging Phenomena ◽  
Sac Solder

The mechanical properties of a lead free solder are strongly influenced by its microstructure, which is controlled by its thermal history including solidification rate and thermal aging after solidification. Due to aging phenomena, the microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal and/or thermal cycling environments. Through uniaxial testing of miniature bulk solder tensile specimens, we have previously demonstrated that large changes occur in the stress-strain and creep behaviors of lead free solder alloys with aging. Complementary studies by other research groups have verified aging induced degradations of SAC mechanical properties. In those investigations, mechanical testing was performed on a variety of sample geometries including lap shear specimens, Iosipescu shear specimens, and custom solder ball array shear specimens. While there are clearly aging effects in SAC solder materials, there have been limited prior mechanical loading studies on aging effects in actual solder joints extracted from area array assemblies (e.g. PBGA or flip chip). This is due to the extremely small size of the individual joints, and the difficulty in gripping them and applying controlled loadings (tension, compression, or shear). In the current work, we have explored aging phenomena in actual solder joints by nano-mechanical testing of single SAC305 lead free solder joints extracted from PBGA assemblies. Using nanoindentation techniques, the stress-strain and creep behavior of the SAC solder materials have been explored at the joint scale for various aging conditions. Mechanical properties characterized as a function of aging include the elastic modulus, hardness, and yield stress. Using a constant force at max indentation, the creep response of the aged and non-aged solder joint materials has also been measured as a function of the applied stress level. With these approaches, aging effects in solder joints were quantified and correlated to the magnitudes of those observed in testing of miniature bulk specimens. Our results show that the aging induced degradations of the mechanical properties (modulus, hardness) of single grain SAC305 joints were similar to those seen previously by testing of larger “bulk” solder specimens. However, due to the single grain nature of the joints considered in this study, the degradations of the creep responses were significantly less in the solder joints relative to those in larger uniaxial tensile specimens. The magnitude of aging effects in multi-grain lead free solder joints remains to be quantified. Due to the variety of crystal orientations realized during solidification, it was important to identify the grain structure and crystal orientations in the tested joints. Polarized light microscopy and Electron Back Scattered Diffraction (EBSD) techniques have been utilized for this purpose. The test results show that the elastic, plastic, and creep properties of the solder joints and their sensitivities to aging are highly dependent on the crystal orientation. In addition, an approach has been developed to predict tensile creep strain rates for low stress levels using nanoindentation creep data measured at very high compressive stress levels.

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