Measurement of Hygroscopic Swelling in Mold Compounds and Its Effect on PEM Reliability

2003 ◽  
Author(s):  
Eric Stellrecht ◽  
Bongtae Han ◽  
Michael Pecht
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Experimental Method ◽  
Lead Frame ◽  
Thermally Induced ◽  
Molding Compounds ◽  
Hygroscopic Swelling ◽  
Swelling Coefficient ◽  
Package Reliability

Hygroscopic stresses arise in a plastic encapsulated microcircuit (PEM) when the mold compound swells upon absorbing moisture and the lead frame, die paddle, and silicon die, do not experience swelling. Similar to the thermal stress produced by the mismatch of coefficients of thermal expansion between adjacent materials, the hygroscopic stress increases as the hygroscopic swelling coefficient of the mold compound increases. Accurate measurement of hygroscopic swelling is essential in assessing the effect of hygroscopic stresses on package reliability. In this paper, a whole-field experimental method to characterize the hygroscopic swelling of mold compounds is proposed. The method is implemented to determine the hygroscopic swelling and the corresponding coefficient of hygroscopic contraction of five commercial molding compounds. A comparison between the hygroscopic and thermally induced mismatch strains in PEMs is presented and its implication on PEMs reliability is discussed.

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 Unravelling thermal stress due to thermal expansion mismatch in metal–organic frameworks for methane storage

2021 ◽  
Author(s):  
Jelle Wieme ◽  
Veronique Van Speybroeck
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Pressure Coefficient ◽  
Metal Organic Frameworks ◽  
Methane Storage ◽  
Thermal Expansion Mismatch ◽  
Thermal Pressure ◽  
Temperature Changes ◽  
Metal Organic ◽  
The Impact

Thermal stress is present in metal–organic frameworks undergoing temperature changes during adsorption and desorption. We computed the thermal pressure coefficient as a proxy for this phenomenon and discuss the impact of thermal expansion mismatch.

Oxidation characteristics of commercial copper-based lead frame surface and the bonding with epoxy molding compounds

2019 ◽  
Vol 99 ◽  
pp. 161-167 ◽  
Author(s):  
Shih-Chieh Chao ◽  
Wei-Chen Huang ◽  
Jen-Hsiang Liu ◽  
Jenn-Ming Song ◽  
Po-Yen Shen ◽  
...  
Keyword(s):  
Lead Frame ◽  
Molding Compounds ◽  
Oxidation Characteristics ◽  
Commercial Copper

Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

Application of an Epoxy Cap in a Flip-Chip Package Design

1989 ◽  
Vol 111 (1) ◽  
pp. 16-20 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Preliminary Test ◽  
Elastic Stability ◽  
Thermally Induced ◽  
Package Design ◽  
Silicone Gels ◽  
Low Modulus ◽  
Supporting Frame

In order to combine the merits of epoxies, which provide good environmental and mechanical protection, and the merits of silicone gels, resulting in low stresses, one can use an encapsulation version, where a low modulus gel is utilized as a major encapsulant, while epoxy is applied as a protecting cap. Such an encapsulation version is currently under consideration, parallel with a metal cap version, for the Advanced VLSI package design which is being developed at AT&T Bell Laboratories. We recommend that the coefficient of thermal expansion for the epoxy be somewhat smaller than the coefficient of thermal expansion for the supporting frame. In this case the thermally induced displacements would result in a desirable tightness in the cap/frame interface. This paper is aimed at the assessment of stresses, which could arise in the supporting frame and in the epoxy cap at low temperatures. Also, the elastic stability of the cap, subjected to compression, is evaluated. The calculations were executed for the Advanced VLSI package design and for a Solder Test Vehicle (STV), which is currently used to obtain preliminary information regarding the performance of the candidate encapsulants. It is concluded that in order to avoid buckling of the cap, the latter should not be thinner than 15 mils (0.40 mm) in the case of VLSI package design and than 17.5 mils (0.45 mm) in the case of STV. At the same time, the thickness of the cap should not be greater than necessary, both for smaller stresses in the cap and for sufficient undercap space, required for wirebond encapsulation. The obtained formulas enable one to evaluate the actual and the buckling stresses. Preliminary test data, obtained by using STV samples, confirmed the feasibility of the application of an epoxy cap in a flip-chip package design.

Measurement and interpretation of stress in copper films as a function of thermal history

1991 ◽  
Vol 6 (7) ◽  
pp. 1498-1501 ◽  
Author(s):  
Paul A. Flinn
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Thermal History ◽  
Copper Films ◽  
Thermally Induced ◽  
Aluminum Films ◽  
Interconnection Material ◽  
Interconnect Systems

Since copper has some advantages relative to aluminum as an interconnection material, it is appropriate to investigate its mechanical properties in order to be prepared in advance for possible problems, such as the cracks and voids that have plagued aluminum interconnect systems. A model previously used to interpret the behavior of aluminum films proves to be, with minor modification, also applicable to copper. Although the thermal expansion of copper is closer to that of silicon and, consequently, the thermally induced strains are smaller, the much larger elastic modulus of copper results in substantially higher stresses. This has implications for the interaction of copper lines with dielectrics.

scholarly journals Real-time observation of the thermally-induced phase transformation in GeTe and its thermal expansion properties

2019 ◽  
Vol 165 ◽  
pp. 327-335 ◽  
Author(s):  
Xuan Quy Tran ◽  
Min Hong ◽  
Hiroshi Maeno ◽  
Youichirou Kawami ◽  
Takaaki Toriyama ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Real Time ◽  
Thermally Induced ◽  
Time Observation ◽  
Real Time Observation

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.

Insights into temperature effects on structural deformation of a cable-stayed bridge based on structural health monitoring

2018 ◽  
Vol 18 (3) ◽  
pp. 778-791 ◽  
Author(s):  
Yi Zhou ◽  
Limin Sun
Keyword(s):  
Thermal Expansion ◽  
Health Monitoring ◽  
Temperature Effects ◽  
Temperature Response ◽  
Field Measurements ◽  
Structural Deformation ◽  
Linear Superposition ◽  
Thermally Induced ◽  
Diurnal Cycles ◽  
Cable Stayed Bridge

Structural deformation is an important consideration in the health monitoring of bridges, and its dependence on temperature variations is quite complex. Based on field measurements performed for an operational cable-stayed bridge, the proposed study investigates mechanisms of thermally induced variations in girder length and mid-span deflection through plane geometric and finite element analyses. The objective of this study is to understand the behaviour of such bridges over annual and diurnal cycles. It has been observed that the girder length and mid-span deflection of a cable-stayed bridge exhibit different modes of the temperature–response correlation. Thermally induced changes in girder length are solely governed by the average girder temperature, and its annual variation in amplitude is significantly larger compared to the diurnal variation. However, thermally induced mid-span deflections are simultaneously influenced by the cable temperature and average girder temperature, and these do not vary monotonously with temperature, thereby resulting in nearly equal variation amplitudes over both annual and diurnal cycles. Temperature-induced deformations of a cable-stayed bridge could well be approximated through multiple linear superposition of thermal-expansion effects of individual components. Besides thermal-expansion coefficients of structural materials, the temperature dependency of mid-span deflection of a symmetrical twin-tower cable-stayed bridge is closely related to the ratio of tower height above the deck to central span of the girder as well as span ratio of the side span to central span. The proposed simplified formulae to estimate the sensitivities of temperature effects could be readily extended to other cable-stayed bridges with different geometric arrangements, thereby providing valuable insights into thermally induced deformation of such bridges.

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