scholarly journals Electrical Interconnection and Bonding by Nano-Locking

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1589
Author(s):  
Jielin Guo ◽  
Yu-Chou Shih ◽  
Frank G. Shi
Keyword(s):  
Contact Area ◽  
Mechanical Performance ◽  
Bond Line ◽  
Device Performance ◽  
Height Distribution ◽  
Metallic Surfaces ◽  
General Applicability ◽  
Bond Line Thickness ◽  
Electrical Interconnection ◽  
Bonding Method

The growing demand for increased chip performance and stable reliability calls for the development of novel off-chip interconnection and bonding methods that can process good electrical, thermal, and mechanical performance simultaneously as well as superior reliability. A chip bonding method with the concept of “nano-locking” (NL) is proposed: the two surfaces are locked together for electrical interconnection, and the connection is stabilized by a dielectric adhesive filled into nanoscale valleys on the interconnecting surfaces. The general applicability of this new method was investigated by applying the method to the die-substrate bonding of two different packages from two different manufacturers. Electrical, optical, and thermal performances as well as reliability tests were carried out. The surface morphology of the bonding package substrates plays an important role in determining the contact resistance at the bonding interfaces. It was shown that samples with different roughness height distribution on the metallic surfaces formed a different total number of contacts and the contact area between the two bonding surfaces under the same bond-line thickness (BLT): a larger number of contact area resulted in a reduced electrical resistance, and thus an improved overall device performance and reliability.

scholarly journals Semiconductor Chip Electrical Interconnection and Bonding by Nano-Locking with Ultra-Fine Bond-Line Thickness

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1901
Author(s):  
Jielin Guo ◽  
Yu-Chou Shih ◽  
Roozbeh Sheikhi ◽  
Jiun-Pyng You ◽  
Frank G. Shi
Keyword(s):  
Electrical Resistance ◽  
Present Method ◽  
Bond Line ◽  
Device Performance ◽  
Metallic Surfaces ◽  
Line Thickness ◽  
Semiconductor Chip ◽  
Bond Line Thickness ◽  
Electrical Interconnection ◽  
Electrical Devices

The potential of an innovation for establishing a simultaneous mechanical, thermal, and electrical connection between two metallic surfaces without requiring a prior time-consuming and expensive surface nanoscopic planarization and without requiring any intermediate conductive material has been explored. The method takes advantage of the intrinsic nanoscopic surface roughness on the interconnecting surfaces: the two surfaces are locked together for electrical interconnection and bonding with a conventional die bonder, and the connection is stabilized by a dielectric adhesive filled into nanoscale valleys on the interconnecting surfaces. This “nano-locking” (NL) method for chip interconnection and bonding is demonstrated by its application for the attachment of high-power GaN-based semiconductor dies to its device substrate. The bond-line thickness of the present NL method achieved is under 100 nm and several hundred times thinner than those achieved using mainstream bonding methods, resulting in a lower overall device thermal resistance and reduced electrical resistance, and thus an improved overall device performance and reliability. Different bond-line thickness strongly influences the overall contact area between the bonding surfaces, and in turn results in different contact resistance of the packaged devices enabled by the NL method and therefore changes the device performance and reliability. The present work opens a new direction for scalable, reliable, and simple nanoscale off-chip electrical interconnection and bonding for nano- and micro-electrical devices. Besides, the present method applies to the bonding of any surfaces with intrinsic or engineered surface nanoscopic structures as well.

scholarly journals Effect of Bond-Line Thickness on Fatigue Crack Growth of Structural Acrylic Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1723
Author(s):  
Yu Sekiguchi ◽  
Chiaki Sato
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Adhesive Bond ◽  
Bond Line ◽  
Loading Conditions ◽  
Fatigue Crack Growth Resistance ◽  
Line Thickness ◽  
Bond Line Thickness

With an increasing demand for adhesives, the durability of joints has become highly important. The fatigue resistance of adhesives has been investigated mainly for epoxies, but in recent years many other resins have been adopted for structural adhesives. Therefore, understanding the fatigue characteristics of these resins is also important. In this study, the cyclic fatigue behavior of a two-part acrylic-based adhesive used for structural bonding was investigated using a fracture-mechanics approach. Fatigue tests for mode I loading were conducted under displacement control using double cantilever beam specimens with varying bond-line thicknesses. When the fatigue crack growth rate per cycle, da/dN, reached 10−5 mm/cycle, the fatigue toughness reduced to 1/10 of the critical fracture energy. In addition, significant changes in the characteristics of fatigue crack growth were observed varying the bond-line thickness and loading conditions. However, the predominance of the adhesive thickness on the fatigue crack growth resistance was confirmed regardless of the initial loading conditions. The thicker the adhesive bond line, the greater the fatigue toughness.

Thermal Conductivity Performance Modeling and Characterization of a Novel Anisotropic Conductive Adhesive Used in Lead-Free Electronics Packaging

2012 ◽  
Author(s):  
Matthew J. Combs ◽  
S. Manian Ramkumar ◽  
Satish Kandlikar
Keyword(s):  
Thermal Conductivity ◽  
Base Material ◽  
Bond Line ◽  
Thermal Interface Material ◽  
The Novel ◽  
Conductive Adhesives ◽  
Curing Conditions ◽  
Bond Line Thickness ◽  
Significant Research ◽  
American Society

The continued desire to utilize an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). The use of ACAs in electrical connections creates bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry. This paper will present the findings of the thermal conductivity performance tests using the novel ACA and its applicability as a thermal interface material and for assembling bottom termination components, power devices, etc. The columns that act as electrical conduction paths also contribute towards the thermal conductivity. The thermal conductivity of the novel ACA was measured utilizing a system that is similar to that in ASTM (American Society of Testing Materials) D5470 standard. The goal was to examine the influence of Bond Line Thickness (BLT), particle loading densities, particle diameters and adhesive matrix curing conditions on the electrical and thermal performance of the novel ACA. This paper will also present a numerical model to describe the thermal behavior of the novel ACA. The novel ACA’s applicability for PCB-level assembly has also been successfully demonstrated by RIT, including base material characterization, effect of process parameters, failures, and long-term reliability. Reliability testing included the investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing.

Paper 17: Microtopography of Surfaces

1967 ◽  
Vol 182 (11) ◽  
pp. 21-30 ◽  
Author(s):  
J. B. P. Williamson
Keyword(s):  
Gaussian Distribution ◽  
Contact Area ◽  
Surface Texture ◽  
Glass Surface ◽  
Surface Density ◽  
Radius Of Curvature ◽  
Height Distribution ◽  
Digital Analysis ◽  
Texture Parameters ◽  
Combining Data

This paper describes an approach to the study of surfaces based on the digital analysis of data obtained from profilometric examinations. This technique is used to determine several new surface texture parameters, including the surface density, height distribution, and mean radius of curvature of the asperities. Recent theories have shown that these are the parameters which control the nature of surface contact. The implications which these ideas have for the science of metrology are discussed. The study also shows that many surfaces have height distributions which are Gaussian, and in particular that the heights of the upper half of most surfaces closely follow a Gaussian distribution. By combining data obtained from many closely spaced parallel profiles it has been possible to reconstruct detailed maps of the surface texture. Two examples are discussed: bead-blasted aluminium, and a glass surface lightly blasted with alumina. One of the advantages of microcartography is that it permits the geometry of the contact between rough surfaces to be studied in detail. A map is given showing the manner in which the contact area between two bead-blasted aluminium surfaces splits into sub-areas, and how these sub-areas are distributed with respect to the surface features of the contacting solids.

Thermal Resistance of Bond-Lines Formed With Composite Thermal Interface Materials

2005 ◽  
Author(s):  
Gary Lehmann ◽  
Hao Zhang ◽  
Arun Gowda ◽  
David Esler
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Resistance ◽  
Bond Line ◽  
Surface Conductance ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Bond Line Thickness ◽  
Matrix Surface ◽  
Interface Materials

Measurements and modeling of the thermal resistance of thin (< 100 microns) bond-lines are reported for composite thermal interface materials (TIMs). The composite TIMs consist of alumina particles dispersed in a polymer matrix to form six different adhesive materials. These model TIMs have a common matrix material and are distinguished by their particle size distributions. Bond-lines are formed in a three-layer assembly consisting of a substrate-TIM-substrate structure. The thermal resistance of the bond-line is measured, as a function of bond-line thickness, using the laser flash-technique. A linear variation of resistance with bond-line thickness is observed; Rbl = β · Lbl + Ro. A model is presented that predicts the effective thermal conductivity of the composite as a function of the particle and matrix conductivity, the particle-matrix surface conductance, the particle volume fraction and the particle size distribution. Specifically a method is introduced to account for a broad, continuous size distribution. A particle-matrix surface conductance value of ∼10W/mm2K is found to give good agreement between the measured and predicted effective thermal conductivity values of the composite TIMs.

Die Attach Process Analysis of Enhanced Stand-off Stopper on Tapeless Leadframe

2020 ◽  
pp. 22-26
Author(s):  
E. Graycochea Jr. ◽  
F. Gomez ◽  
R. Rodriguez ◽  
B. Bacquian
Keyword(s):  
Process Analysis ◽  
Semiconductor Industry ◽  
Bond Line ◽  
Line Thickness ◽  
Design Structure ◽  
Die Attach ◽  
Bond Line Thickness ◽  
Improved Design

Improvement on the process and design is often a reliable way to resolve a problem especially in semiconductor industry. This paper presents a leadframe or semiconductor carrier merged with a stand-off design structure that will maintain a consistent bond line thickness (BLT) criteria for quad-flat no-leads (QFN) packages. Through package and process conceptualization, the stand-off design located on the leadframe underneath the silicon die corners would result to a steady and consistent BLT during die attach process. With the improved design, die tilt occurrence in die attach process would be mitigated.

Electrical conductivity of brine‐saturated fractured rock

Geophysics ◽  
1986 ◽  
Vol 51 (8) ◽  
pp. 1585-1593 ◽  
Author(s):  
R. M. Stesky
Keyword(s):  
Electrical Conductivity ◽  
Fracture Surface ◽  
Contact Area ◽  
Fractured Rock ◽  
Flow Path ◽  
Fracture Plane ◽  
Fracture Aperture ◽  
Height Distribution ◽  
Surface Geometry ◽  
Path Tortuosity

A theoretical analysis shows that electrical conductivity along fractures in a saturated porous rock is a function of many factors: fluid and rock conductivities, initial fracture aperture and contact area, fracture surface geometry (asperity height distribution and tip curvature), elastic moduli of the rock, and confining pressure or normal stress acting across the fracture. The conductivity in the fracture plane decreases approximately in proportion to log pressure, but the conductivity is influenced by the increased contact area, and hence flow‐path tortuosity, along the fracture surface at elevated pressures. Electrical conductivity in fractures is more affected by flow‐path tortuosity than is permeability. The dependence on pressure was tested using laboratory measurements of conductivity through split cores containing ground, saw‐cut surfaces in a variety of rocks under confining pressures to 200 MPa. The conductivity decreased approximately in proportion to log pressure (there was little effect of increased contact area, and hence tortuosity), which suggests that the contact area may not exceed a few percent of the total apparent area. Measurements of gas permeability through the same split cores showed that when the asperity deformation remained largely elastic, permeability and conductivity had a power of 3 relationship. When asperity collapse occurred, as in a dolomitic marble, the powerlaw relation no longer held; permeability decreased more rapidly under pressure than did conductivity. The different influences of porosity and flow aperture may account for the different behaviors of the two transport properties. The theory suggests a number of ways in which fracture parameters may be extracted from field data. Some of the methods rely on the scale dependence and pressure dependence of the fractured‐rock conductivity; other methods require correlating between different physical properties, such as seismic velocity, which are influenced by the presence of fractures.

scholarly journals ANALYSIS OF ADHESIVELY BONDED SINGLE LAP RIVETED JOINT USING ANSYS

2014 ◽  
pp. 169-174
Author(s):  
KALE SURESH ◽  
K.L.N. MURTY ◽  
T.JAYANANDA KUMAR
Keyword(s):  
Life Time ◽  
Bond Line ◽  
Dissimilar Metals ◽  
Adhesively Bonded ◽  
Modeling And Analysis ◽  
Bond Line Thickness ◽  
Riveted Joints ◽  
Element Technique ◽  
Distribution Of Stress ◽  
Dissimilar Thickness

This project deals with the analysis of adhesively bonded single lap riveted joints. The present work involves the appropriate configuration and characterization of these joints for maximum utilization. The present study includes the effectiveness of bond line thickness, the bonded layer configuration. This is also applicable to dissimilar thickness joints, but in this project we have placed the adhesives at different places for riveted joints. The finite element technique was used throughout the analysis of present work. The present work showed that riveted bonded joints are superior in strengthening to the riveted joints. The riveted bonded joint seems to strengthen and balance the stress and distributed uniformly. This improves the efficiency and life time of the riveted joints; this is also applicable to dissimilar thickness and dissimilar metals joints for balancing, uniform distribution of stress and without any effect of corrosion on dissimilar metals. Modeling and analysis of adhesively bonded single riveted lap joint can be done by using ansys with a version of 13.0.

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