An Estimation of Thermal Stress Induced by the Freezing Process for Biological Cell Preservation

1991 ◽  
pp. 235-243
Author(s):  
Sui Lin
Keyword(s):  
Thermal Stress ◽  
Freezing Process ◽  
Biological Cell ◽  
Cell Preservation

Using Encapsulation to Improve the Viability of Cryopreserved Cells

1999 ◽  
Author(s):  
Yoshifumi Matsumoto ◽  
Yukihiro Morinaga ◽  
Masanobu Ujihira ◽  
Kotaro Oka ◽  
Kazuo Tanishita
Keyword(s):  
Cooling Rate ◽  
Pc12 Cells ◽  
Latent Heat ◽  
Ice Crystals ◽  
Freezing Process ◽  
Biological Cell ◽  
Scanning Calorimetry ◽  
Encapsulated Cells ◽  
Pheochromocytoma Pc12 ◽  
Suspended Cells

Abstract The purpose of this study is to clarify whether encapsulated cells have an advantage over suspended cells in cryopreservation. Rat pheochromocytoma (PC12) cells were selected for test biological cell and microencapsulated in alginate-polylysine-alginate membranes. Microencapsulated PC12 cells were frozen with differential scanning calorimetry (DSC) at a cooling rate of 0.5 to 10°C/min, their latent heat was measured among the freezing process over the temperature range 4 to −80°C. Their post-thaw viability were evaluated by dye exclusion assay and dopamine release. As a result, latent heat of encapsulated cells was lower than that of suspended cells at a cooling rate of 0.5 and l°C/min. This is because extra-capsule was frozen and intra-capsule unfrozen, as ice crystals forms in extra-capsule space. Post-thaw viability of microencapsulated PC12 cells was improved at 0.5 and l°C/min compared with that of suspended cells. Therefore, in microencapsulated PC12 cells, achievement of intra-capsule unfrozen condition during freezing leads to reducing the solution effect and improving the viability.

IMPROVED LUMPED-DIFFERENTIAL ANALYSIS OF THE FREEZING PROCESS IN A SUPERCOOLED WATER DROPLET

2020 ◽  
Author(s):  
Emerson Barbosa dos Anjos ◽  
Carolina Palma Naveira Cotta ◽  
Renato Machado Cotta ◽  
Igor Soares Carvalho ◽  
Manish Tiwari
Keyword(s):  
Water Droplet ◽  
Supercooled Water ◽  
Freezing Process ◽  
Differential Analysis

A Latent Issue of Via Resistance: Mechanism and Solution

2018 ◽  
Author(s):  
Wentao Qin ◽  
Scott Donaldson ◽  
Dan Rogers ◽  
Lahcen Boukhanfra ◽  
Julien Thiefain ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Chemical Mechanical Planarization ◽  
Resistance Mechanism ◽  
Formation Enthalpy ◽  
Metal Line ◽  
Device Failure ◽  
Valence Electrons ◽  
Wafer Processing ◽  
Field Failure ◽  
And Tungsten

Abstract Many semiconductor products are manufactured with mature technologies involving the uses of aluminum (Al) lines and tungsten (W) vias. High resistances of the vias were sometimes observed only after electrical or thermal stress. A layer of Ti oxide was found on such a via. In the wafer processing, the post W chemical mechanical planarization (WCMP) cleaning left residual W oxide on the W plugs. Ti from the overlaying metal line spontaneously reduced the W oxide, through which Ti oxide formed. Compared with W oxide, the Ti oxide has a larger formation enthalpy, and the valence electrons of Ti are more tightly bound to the O ion cores. As a result, the Ti oxide is more resistive than the W oxide. Consequently, the die functioned well in the first test in the fab, but the via resistance increased significantly after a thermal stress, which led to device failure in the second test. The NH4OH concentration was therefore increased to more effectively remove residual W oxide, which solved the problem. The thermal stress had prevented the latent issue from becoming a more costly field failure.

An Advanced Reliability Improvement and Failure Analysis Approach to Thermal Stress Issues in IC Packages

2009 ◽  
Author(s):  
Michael Hertl ◽  
Diane Weidmann ◽  
Alex Ngai
Keyword(s):  
Thermal Stress ◽  
Failure Analysis ◽  
Deformation Measurement ◽  
Stress Conditions ◽  
Analysis Approach ◽  
New Approach ◽  
Reliability Improvement

Abstract A new approach to reliability improvement and failure analysis on ICs is introduced, involving a specifically developed tool for Topography and Deformation Measurement (TDM) under thermal stress conditions. Applications are presented including delamination risk or bad solderability assessment on BGAs during JEDEC type reflow cycles.

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