Thermoelastic Behavior of Filled Molding Compounds: Composite Mechanics Approach

2000 ◽  
Vol 123 (3) ◽  
pp. 260-267 ◽  
Author(s):  
M. Uschitsky ◽  
E. Suhir ◽  
G. W. Kammlott
Keyword(s):  
Thermal Expansion ◽  
Integrated Circuit ◽  
Thermal Stresses ◽  
Volume Concentration ◽  
Molding Compounds ◽  
Low Level ◽  
Plastic Packages ◽  
Silica Fillers ◽  
Silicon Materials ◽  
Composite Mechanics

Reliability of epoxy molding compounds used in plastic packages of integrated circuit (IC) devices depends to a great extent on the level of thermal stresses. These are due primarily to the thermal expansion (contraction) mismatch of the epoxy and the silicon materials. In this analysis we assess the effect of silica fillers on the level of thermal stresses. We conclude that thermal stresses in the compound can indeed be reduced by the application of appropriate fillers. We found that the filler volume concentration does not have to be larger than 30 percent to keep the thermal stresses at a sufficiently low level. This number is close to the filler volume concentration of 30–40 percent in commercially available molding compounds. The obtained results and recommendations can be helpful in the analysis of stresses in, and physical design of, plastic packages.

Moisture Diffusion in Epoxy Molding Compounds Filled With Particles

1998 ◽  
Vol 123 (1) ◽  
pp. 47-51 ◽  
Author(s):  
M. Uschitsky ◽  
E. Suhir
Keyword(s):  
Integrated Circuits ◽  
Thermal Stresses ◽  
Experimental Studies ◽  
Moisture Sorption ◽  
Moisture Diffusion ◽  
Filler Concentration ◽  
Mechanical Reliability ◽  
High Concentration ◽  
Molding Compounds ◽  
Plastic Packages

Mechanical reliability of epoxy molding compounds in plastic packages of integrated circuits (IC) is greatly affected by the compound ability to absorb moisture. Accordingly, the objective of the study is to evaluate the effect of moisture sorption on the mechanical properties of the compound. Experimental studies were conducted to evaluate the moisture diffusion in compounds with different, from moderate to high, concentration of silica and alumina nitride fillers. The weight-gained analysis indicated that the moisture diffusion was of non-Fickian type and depended mainly on the specimen’s relative humidity and the filler concentration. We found that although the hygro-thermal stresses, caused by moisture diffusion, were relatively low, such diffusion led to an appreciable decrease in the compound’s strength. Moisture diffusion can result also in a substantial increase in the material’s plasticity. The obtained results can be helpful in the analysis of the mechanical behavior of molding compounds employed in electronic packaging. These results can be used to better understand and to improve the reliability of plastic packages of IC devices.

A bioreporter bioluminescent integrated circuit for very low-level chemical sensing in both gas and liquid environments

2007 ◽  
Vol 123 (2) ◽  
pp. 922-928 ◽  
Author(s):  
R. Vijayaraghavan ◽  
S.K. Islam ◽  
M. Zhang ◽  
S. Ripp ◽  
S. Caylor ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Chemical Sensing ◽  
Low Level

Thermal Expansion Coefficients and Thermal Stresses in an Aligned Short Fiber Composite With Application to a Short Carbon Fiber/Aluminum

1985 ◽  
Vol 52 (4) ◽  
pp. 806-810 ◽  
Author(s):  
Y. Takao ◽  
M. Taya
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Carbon Fiber ◽  
Thermal Stresses ◽  
Short Fiber ◽  
Short Carbon Fiber ◽  
Thermal Expansion Coefficients ◽  
Equivalent Inclusion Method ◽  
Expansion Coefficients ◽  
Short Carbon

A formulation to compute the effective thermal expansion coefficients (αc) of an anisotropic short fiber-reinforced composite and the thermal stress (σ) induced in and around the fiber is developed. The formulation is based on the Eshelby’s equivalent inclusion method. Main emphasis is placed on short Carbon fiber/Aluminum. The thermal stress due to a uniform temperature rise ΔT is computed at points just outside the fiber. The effects of various parameters on αc and σ are also investigated.

Properties of Graphite Interconnect Circuit Boards with Anisotropic Thermal Expansion

1990 ◽  
Vol 216 ◽  
Author(s):  
J. Malamas ◽  
R.P. Bambha ◽  
J.B. Ramsey ◽  
W.C. Garrett ◽  
E.G. Kelso ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Focal Plane ◽  
Thermal Stresses ◽  
Focal Plane Arrays ◽  
Circuit Board ◽  
Circuit Boards ◽  
Anisotropic Thermal Expansion ◽  
Indium Bump

ABSTRACTWe report the investigation of an interconnect circuit board (ICB) with anisotropic thermal expansion for use with bump bonded, indirect hybrid, scanning focal plane arrays. This ICB is designed to reduce significantly the thermal stresses on the indium bump bonds during thermal cycling. Highly oriented pyrolitic graphite (HOPG) was chosen because its anisotropic thermal expansion meets the criteria for forming an indirect hybrid ICB using silicon processor circuits and mecury cadmium telluride detectors. Properties of HOPG influencing its performance as an ICB have been investigated including thermal expansion, electrical conductivity, durability, and adherence of electrically insulating thin films.

Influence of Coating Layer to Reduce Thermal Stresses in Cylindrically Formed Metal Matrix Composites

2000 ◽  
Author(s):  
Fuat Okumus ◽  
Aydin Turgut ◽  
Erol Sancaktar
Keyword(s):  
Thermal Expansion ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Thermal Stresses ◽  
Coating Layer ◽  
Coefficient Of Thermal Expansion ◽  
Aluminum Matrix ◽  
Matrix Composites ◽  
Cylinder Model ◽  
Matrix Layer

Abstract In this study, the use of coating layers is investigated to reduce thermal stresses in the metal matrix composites which have a mismatch in coefficients of thermal expansions in fiber and matrix components. The thermoelastic solutions are obtained based on a three-cylinder model. It is shown that the effectiveness of the layer can be defined by the product of its coefficient of thermal expansion and thickness. Consequently, a compensating layer with a sufficiently high coefficient of thermal expansion can reduce the thermal stresses in the metal matrix. The study is based on a concentric three cylinder model isolating individual steel fibers surrounded with a coating layer and an aluminum matrix layer. Only monotonic cooling is studied.

Designing Lightweight Tensegrity-Based Structures and Materials of Tailorable Thermal Expansion

2019 ◽  
Author(s):  
Rochelle E. Silverman ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Thermal Expansion ◽  
Thermal Stresses ◽  
Low Complexity ◽  
Aerospace Engineering ◽  
Positive Zero ◽  
Large Temperature ◽  
New Materials ◽  
Temperature Changes ◽  
Wide Range ◽  
First Time

Abstract In this work, we analyze and design structures and materials that possess custom thermal expansion. These structures and materials are composed of a base unit inspired by the tensegrity “D-bar” (or double-pyramid) topology. We derive, for the first time, analytical equations for the linearized and geometrically exact coefficients of thermal expansion (CTEs) of bi-material D-bar structures with arbitrary shape and complexity. Numerical results obtained using the geometrically exact CTE equations are compared with results obtained using the linearized CTE equations, showing that the latter are accurate only in cases where temperature changes are small. Further results show that D-bar structures of low complexity can produce a wide range of CTEs, including positive, zero, and negative values. These CTE values are exhibited for a range of materials that allows for easy manufacturing (materials with CTE ratios as low as 2). Thus, it is concluded that D-bar structures show promise for applications in aerospace engineering and other fields where new materials of tailorable thermal expansion are needed to decrease the substantial thermal stresses caused by large temperature changes.

Study of the Influence of Refractories Structure on the Thermomechanical Properties of Tunnel Kiln Equipment Lining

2020 ◽  
Vol 299 ◽  
pp. 150-156
Author(s):  
Tatiana M. Lonzinger ◽  
Vadim A. Skotnikov ◽  
Alexey M. Sukharev
Keyword(s):  
Thermal Expansion ◽  
Thermal Stresses ◽  
Linear Thermal Expansion ◽  
High Strength ◽  
Thermomechanical Properties ◽  
Petrographic Analysis ◽  
Entire Area ◽  
Thermal Expansion Coefficients ◽  
Concrete Blocks ◽  
Tensile Thermal Stress

A study of the influence of refractories’ structure on the thermomechanical properties of the lining of the equipment of tunnel kilns has been carried out. The lining of kiln trolleys is subjected to a mechanical stress distributed evenly over the entire area and the most dangerous to brittle materials, as well as to tensile thermal stresses. The magnitude of the tensile thermal stress depends on the material and the structure of the lining. The mechanisms of destruction of products made of fireclay and liquid concrete have been studied. Mineralogical and petrographic analysis of fireclay refractories have been used, as trolley lining has established metasomatic interaction of the lining with the vapor-gas component of the kiln, as well as with the metal of the trolleys. Monolithic products, made of low-cement concrete with corundum filler, are characterized by high strength and resistance to abrasion. The total value of compression and thermal expansion stresses for them is 3.08 MPa, which is half the value of those of fireclay. When conducting the research to optimize the composition of trolley lining, a technology for manufacturing two-layer concrete blocks, combining the advantages of compositions, based on corundum and fireclay, has been developed. The chemical and granulometric composition of fireclay-based concrete in the lower thermal insulation layer and electrocorundum-based concrete in the upper reinforcing layer were selected in such a way, as to ensure similar values of linear thermal expansion coefficients and prevent possible destruction along the boundary between the layers during the operation.

Effects of Configuration on Plastic Package Stresses

1991 ◽  
Vol 113 (4) ◽  
pp. 397-404 ◽  
Author(s):  
L. T. Nguyen ◽  
S. A. Gee ◽  
W. F. v. d. Bogert
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Stress Reduction ◽  
Stress Profile ◽  
Strain Gages ◽  
Molding Compounds ◽  
Compressive Stresses ◽  
Plastic Packages ◽  
Plastic Package ◽  
Element Simulation

This paper examines the effects of device and leadframe configurations on the stresses encountered in typical Dual-in-Line plastic packages. The parameters studied include the die size, the die pad size, the location of the die with respect to the die pad center, and the die coating configuration. Special piezoresistive strain gages deposited on dies of varying sizes are used to map the stress profile across the die surfaces after molding. Finite element simulation of these effects is also conducted. Results indicate that the compressive stresses from the molding compounds are governed with diminishing influence by the size of the die. Furthermore, rather high compressive stresses are observed in the vicinity of the edges of large dies. More subtle effects are found for the influence of the die pad size, the aspect ratio of the die, and the extent of the die offsetting with respect to the die pad center. Finally, by surrounding the die with a thin trail of silicone gel to provide for lateral cushioning, stress reduction is slightly more effective than in the standard “glob-top” coating.

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