Nano-scale Conductive Films for High Performance Fine Pitch Interconnect

2007 ◽  
Vol 990 ◽  
Author(s):  
Yi Li ◽  
Myung Jin Yim ◽  
Kyung Sik Moon ◽  
ChingPing Wong
Keyword(s):  
High Performance ◽  
Electrical Conductance ◽  
Conductive Adhesives ◽  
Bonding Pressure ◽  
Nano Scale ◽  
Fine Pitch ◽  
Conductive Film ◽  
Joint Resistance ◽  
Conductive Fillers ◽  
Free Solder

ABSTRACTIn this paper, a novel nano-scale conductive film which combines the advantages of both traditional anisotropic conductive adhesives/films (ACAs/ACFs) and nonconductive adhesives/films (NCAs/NCFs) is introduced and developed for next generation high performance ultra-fine pitch packaging applications. This novel interconnect film possesses the properties of electrical conduction along the z-direction with relatively low bonding pressure (ACF-like) and the ultra-fine pitch (< 100 nm) capability (NCF-like). Unlike typical ACF which requires 1–5 vol% of conductive fillers, the novel nano-scale conductive film only needs less than 0.1 vol% conductive fillers to achieve good electrical conductance in the z direction. The nano-scale conductive film also allows a lower bonding pressure than NCF to achieve a much lower joint resistance (over two orders of magnitude lower than typical ACF joints) and higher current carrying capability. With low temperature sintering of nano-silver fillers, the joint resistance of the nano-scale conductive film could be as low as 10−5 Ohm, even lower than the NCF and lead-free solder joints. The reliability of the nano-scale conductive film after high temperature and humidity test (85°C/85%RH) was also improved compared to the NCF joints. As such, a high performance, fine pitch conductive film was developed.

Electromigration Performance of Fine-Pitch Copper Pillar Interconnections

2012 ◽  
Vol 2012 (1) ◽  
pp. 001018-001025
Author(s):  
Ahmer Syed ◽  
Christopher J. Berry ◽  
Karthikeyan Dhandapani ◽  
Patrick Thompson ◽  
Seung-Hyun Chae
Keyword(s):  
Stress Testing ◽  
No Reduction ◽  
Operating Temperature ◽  
Conduction Path ◽  
Package Design ◽  
Fine Pitch ◽  
Joint Resistance ◽  
Two Factors ◽  
Free Solder ◽  
Critical Consideration

The miniaturization trend in electronic packaging continues to drive smaller and smaller chip-to-substrate interconnections with no reduction in IC operating temperature or device power in sight. These two factors (current density and temperature) make the electromigration lifetime of chip-to-package interconnections a critical consideration in package design. Of particular interest these days are the “fine pitch copper pillar” structures due to their very small size (30um dia or less). This paper presents interconnection lifetime and metallurgical data on the same which demonstrates the extreme robustness of these joints due largely to their reaching a fully reacted state in which no free solder exists in the conduction path thus providing electromigration performance like that of the base copper and intermetallic compounds. Joint resistance trends observed during stress testing are also discussed.

Pre-Applied Inter Chip Fill for 3D-IC Chip Joining

2015 ◽  
Author(s):  
Yasuhiro Kawase ◽  
Makoto Ikemoto ◽  
Masaya Sugiyama ◽  
Hidehiro Yamamoto ◽  
Hideki Kiritani
Keyword(s):  
Thermal Conductivity ◽  
Integrated Circuits ◽  
High Performance ◽  
Three Dimensional ◽  
Conductive Filler ◽  
3D Ic ◽  
Fine Pitch ◽  
Silica Filler ◽  
Conductive Fillers ◽  
Process Compatibility

Three dimensional integrated circuits (3D-IC) have been proposed for the purpose of low power and high performance in recent years. Pre-applied inter chip fill is required for fine pitch interconnections, large chips, and also thin chips. In addition to them, pre-applied joining process with high thermal conductive inter chip fill (HT-ICF) is strongly required for the cooling of 3D-IC. Some kinds of matrix resins and thermal conductive fillers were simulated and evaluated for pre-applied ICF. As a result, matrix and cure agent appeared to be important to both pre-applied ICF process compatibility and thermal conductivity, so that we’d selected epoxy type matrix based on controlling super molecular structure due to its mesogen unit. And not only matrix but also filler appeared to be the key to improve thermal conductivity for pre-applied ICF at the same time. The thermal conductivity of conventional silica filler was only 1W/mK, so that, taking into account of thermal conductivity, density and its stability, we’d selected aluminum oxide and boron nitride as thermal conductive filler and optimized HT-ICF for pre-applied process. After composite was mixed and cured, some physical properties were measured and thermal conductivity was 1.8W/mK, CTE was below 21ppm/K and Tg was 120°C. Furthermore, new high thermal conductive filler was also studied. We’d synthesized completely new spherical BN (diameter <5um) and applied it to HT-ICF and the thermal conductivity was almost two times higher than conventional BN. In this study, we confirmed ICF physical characteristics and its pre-applied joining for 3D-IC and void-less joining was also discussed.

High Performance Conductive Adhesives for Lead-Free Interconnects

2006 ◽  
Vol 968 ◽  
Author(s):  
Yi Li ◽  
ChingPing Wong
Keyword(s):  
High Power ◽  
High Performance ◽  
High Current Density ◽  
High Reliability ◽  
Nano Particles ◽  
Electrical Performance ◽  
Conductive Adhesives ◽  
Molecular Monolayers ◽  
Fine Pitch ◽  
Novel Approach

ABSTRACTTin-lead solder alloys are widely used in the electronic industry. With the recognition of toxicity of lead, however, electrically conductive adhesives (ECAs) have been considered as one of the most promising alternatives of tin-lead solder. While silver is the most widely used conductive fillers for ECA, silver migration has been the major concern for the high power and fine pitch applications. In this paper, a novel approach of using self-assembled monolayers (SAMs) passivation has been introduced to control the silver migration in nano-Ag ECAs. The protection of silver nano particles with SAMs reduced the silver migration dramatically and no migration was observed upon application of high voltages (up to 500 V) due to the formation of surface chelating compounds between the SAM and nano silver fillers. Unlike other migration control approaches which sacrifice electrical performance, the SAM passivated nano Ag fillers also enhanced the electrical conductivity and current carrying capability of adhesive joints significantly due to the improved interfacial properties and high current density of those molecular monolayers. The joint resistance of the SAM incorporated nano-Ag conductive adhesive could be achieved as low as 10−5 Ohm (the contact area is 100 ×100 μm2) and the maximum allowable current was higher than 3500 mA. As such, a fine pitch, high performance, non-migration and high reliability adhesives are developed for potential solder replacement in high voltage, high power device applications.

Effects of Surface Cleanness, Bonding Pressure and Contact Area of ACF on Interfacial Impedance of Chip on Glass Bonding in Flat Panel Display Assembly

2007 ◽  
Vol 364-366 ◽  
pp. 618-623
Author(s):  
Jhy Cherng Tsai ◽  
Wen Tsung Wang
Keyword(s):  
Contact Area ◽  
Indium Tin Oxide ◽  
Tension Test ◽  
Flat Panel Display ◽  
Bonding Pressure ◽  
Fine Pitch ◽  
Conductive Film ◽  
Ito Glass ◽  
Temperature Test ◽  
Interfacial Impedance

Chip on glass (COG) bonding using Anisotropic Conductive Film (ACF) is the best process for assembling ICs on thin substrate glass with fine pitch in current practice. This paper investigates the effects of surface cleanness of the substrate, bonding pressure and contact area of COG bonding with ACF on interfacial impedance (II) via experiments. Indium tin oxide (ITO), 350±15nm in thickness, coated on 0.4mm glass is used as the substrate with φ4μm ACF particle in the experiment. Surface cleanness is measured by wetting tension, an alternative measurement of surface energy. Experiments with three levels for each parameter are designed and conducted. Reliability tests, including temperature test, humidity test, cycling test and boiling test, are also conducted to allocate best parameters in the COG bonding process. Experimental results showed that the contact area of ACF must be more than 1,500μm2 in order to provide stable II. Surface cleanness of ITO glass is suggested to be higher than 46 dyne/cm as measured by wetting tension test. Bonding pressure, ranging from 40 to 80 Mpa, does not have strong effect on II. Temperature test under -40°C /30min to 85°C/30min at 120cycle and humility test at 85°C under 85%RH for 500 hours showed that higher surface cleanness results in better bonding result as the variation of II is lower. Boiling test at 121°C under 2atm for 8 hours showed that surface cleanness should be over 46 dyne/cm, as measured by wetting tension test, to ensure stable bonding result.

Triple functions of polyaniline in situ coated on silver powders for high-performance electrically conductive pastes

2021 ◽  
Vol 11 (7) ◽  
pp. 1231-1238
Author(s):  
Maocheng Zhang ◽  
Mengqi Yao ◽  
Ni Wang ◽  
Wencheng Hu
Keyword(s):  
Electrical Resistivity ◽  
High Performance ◽  
Chemical Reduction ◽  
Conductive Adhesive ◽  
Silane Coupling Agents ◽  
Conductive Adhesives ◽  
Electrically Conductive ◽  
Conductive Fillers ◽  
Preparation Strategy

Silver powders, with high electrical conductivity, as the conductive fillers of electrically conductive adhesives have been widely investigated in the fields of microelectronic packaging. Herein, polyaniline (PANI)-coated silver powders were successfully fabricated via a facile chemical reduction, followed by the polymerization of aniline. The PANI plays triple functions to synergistically improve the performance of electrically conductive pastes as follows: (1) The aniline-coated silver particles are used as an ideal dispersant to substitute polyvinyl pyrrolidone and polyethylene glycol in the preparation strategy of silver powders; (2) The polymerization of aniline plays a surface modifier role instead of silane coupling agents to prepare silver-based conductive adhesives with homodisperse silver powders; (3) The high conductivity of PANI could reduce the contact resistance between silver powders and decrease the electrical resistivity of conductive adhesive films significantly. As a result, the PANI coats silver powders (pH = 3) show a decreased electrical resistivity of conductive adhesive films of 4.24×10−5 Ω·cm with the shear resistance of 9.06 MPa and the sheet resistance of 10.6 mΩ.sq−1. This work provides an efficient way to controllably synthesize PANI-coated silver powders for high-performance electrically conductive pastes.

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