Additive Fabricated Compliant Interconnects: Design, Fabrication and Reliability Effects

2020 ◽  
Author(s):  
Tumininu Olatunji ◽  
David Huitink
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Design Parameters ◽  
Thermal Expansion Mismatch ◽  
Test Vehicle ◽  
Mechanical Compliance ◽  
Design And Manufacturing ◽  
Solder Balls ◽  
Solder Joint Fatigue ◽  
On Chip

Abstract Electronics packaging development is greatly dependent on the magnitude of interconnect and on-chip stress that ultimately limits the reliability of electronic components. Thermomechanical strains occur because of the coefficient of thermal expansion mismatch from different conjoined materials being assembled to manufacture a device. To curb the effect of thermal expansion mismatch, studies have been done in integrating compliant structures between dies, solder balls, and substrates. Initial studies have enabled the design and manufacturing of these structures using a photolithography approach which involves an increased number of fabrication steps depending on the complexity of the structures. This current study involves the fabrication of these structures using a different approach, utilizing additive manufacturing that reduces the number of fabrication steps required to obtain compliant geometries, while also providing a platform for unique compliant structures. This paper discusses the method of fabrication and analyzes the properties and effects of these interconnect structures on a die. Structural finite element thermal cycling simulations between −40 to 125°C show about a 115% increase in the solder joint fatigue life. Additionally, fabricated test structures created directly on a PCB were experimentally characterized for compliance using a micro-indenter tester, showing a mechanical compliance range of 265.95 to 656.78 μ/N for selected design parameters to be integrated into a test vehicle.

scholarly journals Grain Refinement Of Magnesium and Az19E Magnesium Alloy By Addition Of MgB2 Inoculant

2021 ◽  
Author(s):  
Payam Emadi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Thermal Expansion ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Coefficient Of Thermal Expansion ◽  
Fuel Efficiency ◽  
Grain Refining ◽  
Nano Particle ◽  
Thermal Expansion Mismatch

The increased use of magnesium alloys with improved mechanical properties is a prominent strategy towards increasing fuel efficiency of vehicles and decreasing emissions. This study investigates the grain refining efficiency and fading of MgB2 micro- and nano-particle added Pure Mg and AZ91E. Addition of micro and nano-sized MgB2 provided a reduction in grain size for Pure Mg and AZ91E. Enhanced heterogeneous nucleation and grain growth restriction was believed to be the source of refinement. Fading was observed for both Pure Mg and AZ91E, with the nano-particle added castings showing an increased resistance. The elongation of the Pure Mg samples showed improvements, whereas no improvements for UTS and YS was seen. The improved ductility was believed to be due to the grain refinement and coefficient of thermal expansion mismatch. The AZ91E samples did not show improvements in mechanical properties. This was believed to be due to stress concentration from Al-Mn intermetallics.

Study of Thermo-Mechanical Reliability of TSV for 8-Layer Stacked Multi Chip Package

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001697-001725
Author(s):  
Sung-Hoon Choa ◽  
Jin Young Choi ◽  
Cha Gyu Song ◽  
Haeng Soo Lee
Keyword(s):  
Thermal Expansion ◽  
Fatigue Life ◽  
Thermal Fatigue ◽  
Coefficient Of Thermal Expansion ◽  
Influential Factors ◽  
Design Parameters ◽  
Mechanical Reliability ◽  
Thermal Fatigue Life ◽  
The Impact ◽  
Underfill Material

Through silicon via (TSV) technology is becoming a hot topic for three dimensional integration in IC packaging industry. However, TSV technology raises several reliability concerns particularly caused by thermally induced stress. In this study, the thermo-mechanical reliability of copper TSV technology for the multi chip packaging was investigated using finite element method. For the multi chip package design, the 8-layer stacked chip packaging with TSV structure has been constructed as our test vehicle. The numerical analysis of stress/strain distribution and thermal fatigue life prediction were performed in order to study the impact of several design parameters such as via diameter, via pitch, die thickness, bonding pad geometry. The effects of various underfill materials which have different Young¡¯s modulus and coefficients of thermal expansion (CTEs) were also investigated. The DOE (design of experiment) analysis was performed to find the optimal design conditions for 8-layer multi chip package. The most influential factors for the stress reduction are TSV diameter and the coefficient of thermal expansion of underfill material. The larger via diameter and lower CTE showed the smaller stress distribution. On the other hand, thermal fatigue life increases with via diameter, and becomes maximum at via diameter of 20 um, then decrease with increasing via diameter. The presence of underfill material significantly increased the thermal fatigue life of TSV structure. The bonding pad design is also important for TSV durability. The smaller bonding pad showed less stress and higher thermal fatigue life. The characteristics of warpage for 8-layer multi chip package were also investigated.

scholarly journals Grain Refinement Of Magnesium and Az19E Magnesium Alloy By Addition Of MgB2 Inoculant

2021 ◽  
Author(s):  
Payam Emadi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Thermal Expansion ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Coefficient Of Thermal Expansion ◽  
Fuel Efficiency ◽  
Grain Refining ◽  
Nano Particle ◽  
Thermal Expansion Mismatch

The increased use of magnesium alloys with improved mechanical properties is a prominent strategy towards increasing fuel efficiency of vehicles and decreasing emissions. This study investigates the grain refining efficiency and fading of MgB2 micro- and nano-particle added Pure Mg and AZ91E. Addition of micro and nano-sized MgB2 provided a reduction in grain size for Pure Mg and AZ91E. Enhanced heterogeneous nucleation and grain growth restriction was believed to be the source of refinement. Fading was observed for both Pure Mg and AZ91E, with the nano-particle added castings showing an increased resistance. The elongation of the Pure Mg samples showed improvements, whereas no improvements for UTS and YS was seen. The improved ductility was believed to be due to the grain refinement and coefficient of thermal expansion mismatch. The AZ91E samples did not show improvements in mechanical properties. This was believed to be due to stress concentration from Al-Mn intermetallics.

A cautionary tale on the use of GE-7031 varnish: low-temperature thermal expansion studies of ScF3

2013 ◽  
Vol 46 (3) ◽  
pp. 823-825 ◽  
Author(s):  
Cody R. Morelock ◽  
Matthew R. Suchomel ◽  
Angus P. Wilkinson
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Rhombohedral Phase ◽  
Thermal Expansion Mismatch ◽  
X Ray Diffraction ◽  
Electrical Insulator ◽  
Sample Matrix ◽  
Cell Volumes

GE-7031 varnish, a commonly used low-temperature adhesive and electrical insulator owing to its high thermal conductivity and mechanical strength at low temperatures, was used as a sample matrix for low-temperature powder X-ray diffraction measurements of the negative thermal expansion (NTE) material ScF3. When ScF3powder was mixed with GE-7031 varnish, an unexpected cubic to rhombohedral phase transition in the ScF3sample was observed at ∼50 K, and it exhibited smaller low-temperature unit-cell volumes than samples without the varnish matrix. Experimental observations and quantitative estimates suggest that these anomalies are the result of stress induced by a thermal expansion mismatch between the varnish matrix (large positive coefficient of thermal expansion, CTE) and ScF3(quite large negative CTE). The use of GE-7031 varnish as a sample matrix for low-temperature measurements should be approached with caution if a large thermal expansion mismatch is expected.

Characterization of the coefficient of thermal expansion and its effect on the performance of Portland cement concrete pavements

2011 ◽  
Vol 38 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Yoonseok Chung ◽  
Hak-Chul Shin
Keyword(s):  
Thermal Expansion ◽  
Portland Cement ◽  
Coefficient Of Thermal Expansion ◽  
Prediction Equation ◽  
Design Parameters ◽  
Concrete Pavements ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Coarse Aggregates ◽  
Inaccurate Estimation

The coefficient of thermal expansion (CTE) of concrete is considered to be an important design parameter to predict Portland cement concrete (PCC) pavement performance in mechanistic-empirical pavement design guide (MEPDG). This study measured CTE values of concrete specimens having various coarse aggregates, and investigated the relationship between the CTE and critical design parameters. It was found that aggregate types, the amount of coarse aggregate, and relative humidity (RH) had a statistically significant impact on the CTE. Expansion CTE had a higher variation compared to contraction CTE, and the maximum value of expansion CTE at 63% RH was 8% higher than the value at 100% RH. Sensitivity analysis showed that inaccurate estimation of concrete CTE can cause serious error in predicting the performance of PCC pavements. A prediction equation of concrete CTE was introduced by modifying Hansen’s model and the predicted CTE value had a good agreement with the measured CTE.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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