Highly Flexible Die Attach Adhesives for MEMS packages

2012 ◽  
Vol 2012 (1) ◽  
pp. 001169-001177 ◽  
Author(s):  
Tobias Königer
Keyword(s):  
Mechanical Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Assembly Process ◽  
Processing Times ◽  
Heat Curing ◽  
Die Attach ◽  
Negative Effect ◽  
Dual Curing ◽  
Flexible Die

Die attach materials for most MEMS packages must be highly flexible as temperature changes during the assembly process and application may lead to thermo-mechanical stress as a consequence of dissimilar coefficients of thermal expansion of substrate, chip and adhesive. Thermo-mechanical stress results in a distortion of the signal characteristics of the extremely stress-sensitive MEMS device. Within the scope of this paper, highly flexible heat-curing adhesives with a Young's modulus down to 5 MPa (0.725 ksi) at room temperature were developed. DMTA measurements show that temperature storage at +120 °C (+248 °F) does not cause the adhesive to embrittle, which would have a negative effect on the MEMS package's reliability. After storage at +120 °C (+248 °F) for up to 1000 h, no increase in Young's modulus can be observed. The adhesives cure at extremely low temperatures down to +100 °C (+212 °F), which reduces stress development during the assembly process. In addition, the adhesives have very process-friendly properties. Processing times of more than one week can be achieved. The option of dual curing enables preliminary light fixation of the chip within just seconds.

Indentation Tests for Sintered Silver in Die-Attach Interconnection After Thermal Cycling

2021 ◽  
Author(s):  
Fei Qin ◽  
Shuai Zhao ◽  
Yanwei Dai ◽  
Lingyun Liu ◽  
Tong An ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Silver Layer ◽  
Thermal Cycles ◽  
Nano Indentation ◽  
Die Attach ◽  
Indentation Tests ◽  
Sintered Silver

Abstract Thermo-mechanical reliability assessment for sintered silver is a crucial issue as sintered silver is a promising candidate of die-attachment materials for power devices. In this paper, the nano-indentation tests are performed for sintered silver in typical die-attach interconnection under different thermal cycles. Based on thermal cycling test, the Young's modulus and hardness of sintered silver layer have been presented. It is found that the Young's modulus and hardness of sintered silver layer changes slightly although the microstructure of sintered silver also presents some variations. The stress and strain curves for different thermal cycling tests for sintered silver based on reverse analysis of nano-indentation are also given. The results show that the elastoplastic constitutive equations change significantly after thermal cycling tests, and the yielding stress decreases remarkably after 70 thermal cycles. The experimental investigation also show that the cracking behaviors of sintered silver depends on its geometry characteristics, which implies that the possible optimization of sintered silver layer could enhance its thermo-mechanical performance.

scholarly journals A Study of the Effects of Al, Cr, Hf, and Ti Additions on the Microstructure and Oxidation of Nb-24Ti-18Si Silicide Based Alloys

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1579 ◽  
Author(s):  
Jack Nelson ◽  
Mohammad Ghadyani ◽  
Claire Utton ◽  
Panos Tsakiropoulos
Keyword(s):  
Solid Solution ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Isothermal Oxidation ◽  
Bulk Alloy ◽  
Simultaneous Addition ◽  
Hardening Effect ◽  
Heat Treated ◽  
Alloy Oxidation ◽  
Negative Effect

In Nb-silicide based alloys Al, Cr, Hf, and Ti additions are crucial for achieving balance of properties. It is not known how the simultaneous addition of Hf with Al and Ti, or Hf with Al, Cr, and Ti affects macrosegregation, and how the alloying affects hardness, Young’s modulus and bulk alloy oxidation, and contamination of the solid solution Nbss and the Nb5Si3 compound by oxygen. Two alloys with nominal compositions (at.%) Nb-24Ti-18Si-5Al-5Hf (alloy NbSiTiHf-5Al) and Nb-24Ti-18Si-5Al-5Cr-5Hf (alloy NbSiTiHf-5Al-5Cr) were studied in the as-cast and heat-treated conditions and after isothermal oxidation at 800 and 1200 °C and were compared with similar alloys without Hf. In both alloys there was macrosegregation of Si and Ti, which was more severe in NbSiTiHf-5Al. Both alloys formed Nbss+βNb5Si3 eutectic. The Nbss was stable and its Al and Cr concentrations increased with increasing Ti concentration. In both conditions the βNb5Si3 was observed in the alloys NbSiTiHf-5Al and NbSiTiHf-5Al-5Cr, and the γNb5Si3 only in the alloy NbSiTiHf-5Al. In both heat-treated alloys, separate Hf-rich Nb5Si3 grains were formed. The Si and Al concentrations in Nb5Si3 respectively decreased and increased with increasing Ti concentration. Al and Cr had a stronger hardening effect in the Nbss than Al, Cr, and Hf. Al, Cr, and Ti had a stronger negative effect on the Young’s modulus of the Nbss compared with Al, Cr, Hf, and Ti. When Nb was substituted by Ti, Cr, and Hf, and Si by Al in the βNb5Si3, the Young’s modulus was reduced compared with the unalloyed silicide. At 800 °C both alloys did not exhibit catastrophic pest-oxidation after 100 h. The Nbss and Nb5Si3 were contaminated by oxygen in both alloys, the former more severely. At 1200 °C the scales spalled-off, more severely in the alloy NbSiTiHf-5Al, where substrate that was heavily contaminated by oxygen below the scale also spalled-off. In both alloys the contamination of Nb5Si3 and Nbss by oxygen was more severe compared with 800 °C, but the silicides were not contaminated by oxygen in their bulk. The Nbss was not contaminated by oxygen only in the bulk of the alloy NbSiTiHf-5Al-5Cr.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

Degradation of Rocks, Through Cracking Caused by Differential Thermal Expansion, in Relation to Nuclear Waste Repositories

1981 ◽  
Vol 6 ◽  
Author(s):  
J.R. Mclaren ◽  
R.W. Davidge ◽  
I. Titchell ◽  
K. Sincock ◽  
A. Bromley
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Crack Density ◽  
Granitic Rocks ◽  
Multiphase Materials ◽  
Thermal Expansion Behaviour ◽  
Waste Repositories ◽  
Expansion Behaviour

ABSTRACTHeating to temperatures up to 500°C, gives a reduction in Young's modulus and increase in permeability of granitic rocks and it is likely that a major reason is grain boundary cracking. The cracking of grain boundary facets in polycrystalline multiphase materials showing anisotropic thermal expansion behaviour is controlled by several microstructural factors in addition to the intrinsic thermal and elastic properties. Of specific interest are the relative orientations of the two grains meeting at the facet, and the size of the facet; these factors thus introduce two statistical aspects to the problem and these are introduced to give quantitative data on crack density versus temperature. The theory is compared with experimental measurements of Young's modulus and permeability for various rocks as a function of temperature. There is good qualitative agreement, and the additional (mainly microstructural) data required for a quantitative comparison are defined.

Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

2020 ◽  
Vol 12 ◽  
Author(s):  
S.V. Kontomaris ◽  
A. Malamou ◽  
A. Stylianou
Keyword(s):  
Young’S Modulus ◽  
Biological Samples ◽  
Young's Modulus ◽  
Reference Sample ◽  
Nonlinear Behavior ◽  
Accurate Method ◽  
Accurate Solution ◽  
Hertz Model ◽  
Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

Effect of Microcrystalline Cellulose from Banana Stem Fiber on Mechanical Properties and Crystallinity of PLA Composite Films

2011 ◽  
Vol 695 ◽  
pp. 170-173 ◽  
Author(s):  
Voravadee Suchaiya ◽  
Duangdao Aht-Ong
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Microcrystalline Cellulose ◽  
Young's Modulus ◽  
Agricultural Waste ◽  
Composite Films ◽  
Sem Image ◽  
Biocomposite Films ◽  
Twin Screw ◽  
Banana Stem

This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites

scholarly journals Out-of-Plane Thermal Expansion Coefficient and Biaxial Young’s Modulus of Sputtered ITO Thin Films

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 153
Author(s):  
Chuen-Lin Tien ◽  
Tsai-Wei Lin
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Young's Modulus ◽  
Heating Temperature ◽  
Glass Substrates ◽  
Ito Thin Films

This paper proposes a measuring apparatus and method for simultaneous determination of the thermal expansion coefficient and biaxial Young’s modulus of indium tin oxide (ITO) thin films. ITO thin films simultaneously coated on N-BK7 and S-TIM35 glass substrates were prepared by direct current (DC) magnetron sputtering deposition. The thermo-mechanical parameters of ITO thin films were investigated experimentally. Thermal stress in sputtered ITO films was evaluated by an improved Twyman–Green interferometer associated with wavelet transform at different temperatures. When the heating temperature increased from 30 °C to 100 °C, the tensile thermal stress of ITO thin films increased. The increase in substrate temperature led to the decrease of total residual stress deposited on two glass substrates. A linear relationship between the thermal stress and substrate heating temperature was found. The thermal expansion coefficient and biaxial Young’s modulus of the films were measured by the double substrate method. The results show that the out of plane thermal expansion coefficient and biaxial Young’s modulus of the ITO film were 5.81 × 10−6 °C−1 and 475 GPa.

scholarly journals Correction to: Hydric Cycle Impacts on COx Argillite Permeability and Young’s Modulus

2021 ◽  
Vol 54 (3) ◽  
pp. 1149-1149
Author(s):  
Zhibo Duan ◽  
Frédéric Skoczylas ◽  
Chuanrui Wang ◽  
Jean Talandier
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus
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