Modeling of thermal stresses in metal interconnects: Effects of line aspect ratio

1997 ◽  
Vol 82 (4) ◽  
pp. 1578-1581 ◽  
Author(s):  
Y.-L. Shen
Keyword(s):  
Aspect Ratio ◽  
Thermal Stresses ◽  
Metal Interconnects

Through Si Vias Using Liquid Metal Conductors for Re-workable 3D Electronics

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 001343-001357
Author(s):  
George A. Hernandez ◽  
Daniel Martinez ◽  
Stephen Patenaude ◽  
Charles Ellis ◽  
Michael Palmer ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Failure Analysis ◽  
Thermal Stresses ◽  
Electrical Contact ◽  
Additional Information ◽  
Comb Structure ◽  
Via Holes ◽  
Metal Interconnects ◽  
Electroplated Copper ◽  
Silicon Vias

This paper describes the design and fabrication of liquid metal interconnects (vias) for 2.5D and 3D integration. The liquid metal is gallium indium eutectic with a melting temperature of approximately 15.7°C that is introduced into via openings of a silicon interposer. This liquid interconnect technology can be integrated with existing interposer technologies, such as capacitors and traditional (solid metal) through-silicon vias (TSVs). In addition, liquid metal interconnects can better accommodate thermal stresses and provide re-workability in case of chip failure. Our research efforts are focused on the integration of multi-chip modules using liquid metal interconnects. Our study encompasses Direct Current (D.C.) measurements and failure analysis using snake and comb structures at low temperature (10 degrees Kelvin) to slightly above room temperature (300 degrees Kelvin). The snake and comb structure allows us to measure electrical shorts and opens, as well as provide estimates of via yield and allows additional information for determination of possible failure mechanisms. In order to make electrical contact to the liquid metal interconnect interposer from both the top and bottom, test coupons have been fabricated with arrays of large numbers of vias. The interposer structure consists of a thin (200 um thick) silicon wafer with via holes filled with liquid metal. The test coupon consists of bottom and top silicon die with a thickness of 500 um. The bottom wafer incorporates a 2 um-thick daisy-chain metallization and 100 um copper tall vias, which are electrically isolated from each other and the underlying Si by patterned AL-X dielectric. The top wafer incorporates an array of 80 um tall, electroplated copper pillars and top daisy-chain metallization. Liquid metal containment mechanisms and structures have also been investigated. In our presentation we will describe the design, fabrication and characterization of this re-workable interposer with liquid metal interconnects. We will present D.C. resistance and X-ray imagery of the liquid metal filled via. In addition, we will provide failure analysis of via yield per chip.

Analysis of average thermal stresses in passivated metal interconnects

1999 ◽  
Vol 86 (11) ◽  
pp. 6088-6095 ◽  
Author(s):  
A. Wikström ◽  
P. Gudmundson ◽  
S. Suresh
Keyword(s):  
Thermal Stresses ◽  
Metal Interconnects ◽  
Passivated Metal

Note on the thermal stresses in passivated metal interconnects

2001 ◽  
Vol 79 (11) ◽  
pp. 1706-1708 ◽  
Author(s):  
P. Sharma ◽  
H. Ardebili ◽  
J. Loman
Keyword(s):  
Thermal Stresses ◽  
Metal Interconnects ◽  
Passivated Metal

Loss of Stiffness in a Heated Wing: An Inequality

1963 ◽  
Vol 67 (627) ◽  
pp. 191-191 ◽  
Author(s):  
E. H. Mansfield
Keyword(s):  
Aspect Ratio ◽  
Present Author ◽  
Thermal Stresses ◽  
Torsional Stiffness ◽  
Flexural Stiffness ◽  
One Dimensional ◽  
Low Aspect Ratio ◽  
The One ◽  
Proportional Reduction ◽  
Number Of Authors

The loss of torsional or flexural stiffness due to thermal stresses in a thin solid wing is now well known and has been considered by a number of authors, e.g. Dryden and Duberg, Vosteen and Fuller, Bisplinghoff, Hoff, Budiansky and Mayers, Argyris, and the present author. Exact analyses are available only for the “one-dimensional” case of a wing of infinite aspect ratio with arbitrary chordwise distribution of wing thickness and temperature. The loss of stiffness in a similar wing of finite aspect ratio is not as great and, in particular, the proportional reduction in flexural stiffness in a low aspect ratio wing will tend to be less than the proportional reduction in torsional stiffness.

scholarly journals A computational method for detecting aspect ratio and problematic features in additive manufacturing

2021 ◽  
Author(s):  
Ruihuan Ge ◽  
Joseph Flynn
Keyword(s):  
Additive Manufacturing ◽  
Aspect Ratio ◽  
Thermal Stresses ◽  
Computational Method ◽  
Thin Wall ◽  
Thin Walls ◽  
Dimensionless Ratio ◽  
Complex Features ◽  
Further Development ◽  
Metal Additive

AbstractIn metal additive manufacturing, geometries with high aspect ratio (AR) features are often associated with defects caused by thermal stresses and other related build failures. Ideally, excessively high AR features would be detected and removed in the design phase to avoid unwanted failure during manufacture. However, AR is scale and orientation independent and identifying features across all scales and orientations is exceptionally challenging. Furthermore, not all high AR features are as easy to recognise as thin walls and fine needles. There is therefore a pressing need for further development in the field of problematic features detection for additive manufacturing processes. In this work, a dimensionless ratio (D1/D2) based on two distance metrics that are extracted from triangulated mesh geometries is proposed. Based on this method, geometries with different features (e.g. thin wall, helices and polyhedra) were generated and evaluated to produce metrics that are similar to AR. The prediction results are compared with known theoretical AR values of typical geometries.By combining this metric with mesh segmentation, this method was further extended to analyse the geometry with complex features. The proposed method provides a powerful, general and promising way to automatically detect high AR features and tackle the relevant defect issues prior to manufacture.

An Analytical Method for Free Vibration Analysis of Composite Beams Subjected to Initial Thermal Stresses

2011 ◽  
Vol 482 ◽  
pp. 1-9
Author(s):  
A. Mahi ◽  
E.A. Adda-Bedia ◽  
A. Benkhedda
Keyword(s):  
Aspect Ratio ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Thermal Stresses ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Shear Deformation Theory ◽  
Free Vibration Analysis ◽  
Composite Beams ◽  
Ply Orientation

The purpose of this paper is to present exact solutions for the free vibration of symmetrically laminated composite beams. The present analysis includes the first shear deformation theory and the rotary inertia. The analytical solutions take into account the thermal effect on the free vibration characteristics of the composite beams. In particular, the aim of this work is to derive the exact closed-form characteristic equations for common boundary conditions. The different parameters that could affect the natural frequencies are included as factors (aspect ratio, thermal load-to-shear coefficient, ply orientation) to better perform dynamic analysis to have a good understanding of dynamic behavior of composite beams. In order to derive the governing set of equations of motion, the Hamilton’s principle is used. The system of ordinary differential equations of the laminated beams is then solved and the natural frequencies’ equations are obtained analytically for different boundary conditions. Numerical results are presented to show the influence of temperature rise, aspect ratio, boundary conditions and ply orientation on the natural frequencies of composite beams.

Experimental Study of Micro Tools Fabricated by Electrochemical Machining

2010 ◽  
Author(s):  
Ronnie Mathew ◽  
Sagil James ◽  
M. M. Sundaram
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Thermal Stresses ◽  
Electrochemical Machining ◽  
Experimental Conditions ◽  
Aspect Ratios ◽  
Micro Holes ◽  
Machining System ◽  
Micro Tool ◽  
Micro Tools

Accurate and precise micro tools are essential for the micromachining of highly complex features in a wide variety of engineering materials including metals and ceramics. Simple shapes like cylindrical rods with micrometer level dimensions are increasingly being used as micro tools in processes such as micro ultrasonic machining. High aspect ratio tools are necessary to produce deep micro holes and other high aspect ratio structures. Micro tools produced by the well known wire electro-discharge grinding suffer from deformation due to the thermal stresses. Therefore, alternate micro tool manufacturing techniques are being explored actively. In this paper, the manufacturing of micro tools by micro electrochemical machining (ECM) is discussed. The micro tools are made under different experimental conditions using an in-house built micro electrochemical machining system and analyzed for tool tip radii and cone angles. Further, the feasibility of extremely high aspect ratio micro tools is studied. Using micro ECM, micro tools having mean diameters of 10 microns with tips as small as 50 nm and aspect ratios of the order of 300 are achieved.

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