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Several attempts have been made to lower the price of materials in the semiconductor market. Among them, the wire used for interconnection has a disadvantage of high material price in the field of using gold. Many packages have evolved to other technologies to improve performance and are moving away from wire bonding process, but many packages still use bonding wires. In the bonding wire market, in order to reduce prices, gold is being replaced by inexpensive copper, and now the market for copper wire coated with precious metals considering workability is dominant. [1], [5] However, due to the rigid nature of copper, packages with sensitive wiring structures are difficult to apply. [2] Silver alloy wire and noble metal coated silver wire have been developed to lower the wire price of these sensitive packages. [3] In the case of the recently developed noble metal coated silver wire, unlike a silver alloy bonding wire, a spherical ball shape can be realized without using inert gas when forming a Free Air Ball. Due to these advantages, it has recently been in the spotlight as a wire for replacing Au wire. [3] In this paper, experiments were conducted on the bonding conditions of silver wire coated with noble metals. The bondability of the prepared noble metal-coated silver wire according to the Free Air Ball formation conditions was verified. Specifically, evaluation was performed according to the current change at the time of Electronic Flame Off, the type of inert gas, and the size of the Free Air Ball. The evaluation confirmed the optimum bonding conditions for the application of the noble metal coated silver wire.

To suppress the bonding strength degradation of solder joints in automotive electronics, we proposed a mid-temperature quaternary Pb-free Sn-0.5Cu solder alloy with minor Pd, Al, Si and Ge alloying elements. We manufactured powders and solder pastes of Sn-0.5Cu-(0.01,0.03)Al-0.005Si-(0.006–0.007)Ge alloys (T m = 230°C), and vehicle electronic control units used for a flame-retardant-4 printed circuit board with an organic solderability preservative finish were assembled by a reflow soldering process. To investigate the degradation properties of solder joints used in engine compartments, thermal cycling tests were conducted from −40°C to 125°C (10 min dwell) for 1500 cycles. We also measured the shear strength of the solder joints in various components and observed the microstructural evolution of the solder joints. Based on these results, intermetallic compound (IMC) growth at the solder joints was suppressed by minor Pd, Al and Si additions to the Sn-0.5Cu alloy. After 1500 thermal cycles, IMC layers thicknesses for 100 parts per million (ppm) and 300 ppm Al alloy additions were 6.7 μm and 10 μm, compared to the as-reflowed bonding thicknesses of 6 μm and 7 μm, respectively. Furthermore, shear strength degradation rates for 100 ppm and 300 ppm Al(Si) alloy additions were at least 19.5%–26.2%. The cause of the improvement in thermal cycling reliability was analyzed using the (Al,Cu)-Sn, Si-Sn and Al-Sn phases dispersed around the Cu6Sn5 intermetallic at the solder matrix and bonding interfaces. From these results, we propose the possibility of a mid-temperature Sn-0.5Cu(Pd)-Al(Si)-Ge Pb-free solder for automotive engine compartment electronics.

Au Bonding wire, which has been widely used in the semiconductor PKG market, is being converted into Cu Bonding wire due to a sharp increase in Au price. The price of Cu is cheaper than Au and Pd coated wire products with improved reliability and workability have been introduced, bringing a large portion of Au Bonding wire usage. However, the sensitive structure of the PKG still uses Au Bonding wire, because of the problem of pad cratering due to the high workhardening of Cu, so the Au Bonding wire cannot be converted to a cheap Cu Bonding wire despite the high Au price. Recently, Ag alloy Bonding wire has been widely evaluated as a low cost Bonding wire for PKG with sensitive structure. However, like the Cu Bonding wire, a gas kit and an inert gas are required to prevent oxidation when forming a FAB (Free Air Ball, the following notation is unified FAB) for ball Bonding. In addition, the high-humidity reliability level of silver alloy Bonding wire is lower than that of Au Bonding wire. In this study, we evaluated the metal coated silver bonding wire as a next generation low cost bonding wire product to replace Au Bonding wire. In order to improve the disadvantages of the Ag alloy Bonding wire in which the elliptical FAB is formed when the inert gas is not used in the 1st ball Bonding, the noble metal coating is performed on the high purity Ag alloy Bonding wire. Gas free Bonding characteristics and high humidity reliability performance were evaluated according to the kind and thickness of noble metal. In the evaluation of high humidity reliability, metal coated silver Bonding wire showed a high humidity reliability performance more than 2 times compared to the conventional silver alloy Bonding wire. Metal coated silver Bonding wire is expected to be an alternative to the new low cost Bonding wire in the PKG market due to gas free Bonding and improved high humidity reliability performance.

Bulk all-solid-state batteries made with mechanochemically prepared Li2S-P2S5 glass-ceramic electrolytes 1‐3 are a safe alternative to conventional Li-ion batteries because sulfide based glass-ceramic electrolytes are pure ionic conductors, non-volatile, non-flammable, and stable versus lithium metal. However, the use of lithium metal anodes in all-solid-state batteries (ASSBs) is not straightforward because dendritic lithium can penetrate porous cold-compacted glassceramic electrolyte separators. To demonstrate this point, an interfacial instability that was observed by a previous study may be better characterized as an internal short. 4 To improve cell cycleability and survivability a recent study has demonstrated that the vapor deposition of thin lithium films onto Li2S-P2S5 glass-ceramic solid-state electrolyte (SSE) pellets can improve electrolyte-lithium electrode in

We investigated the effect of Pd concentration in Pd-doped Ag wires on the humidity reliability and interfacial corrosion characteristics between Ag wire and Al metallization. Additionally, we confirmed no corrosion problem between Ag wire and noble metal (Pd, Au) metallization, even after a pressure cooker test (PCT). The chemical composition of the tested Ag wires was pure Ag, Ag-1wt% Pd and Ag-3wt% Pd. These wires were bonded to Al and noble metal (Au, Pd) metallization using a thermo-sonic bonder. The interfaces were characterized by focused ion beam (FIB), high resolution transmission electron microscope (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The interface corrosion of Pd doped Ag wires was significantly reduced as the Pd concentration in the Ag wires increased. Furthermore, the Ag wires on the noble metal (Au, Pd) metallization exhibited stable reliability during the PCT.

This paper reports a Si-Ti-Ni ternary alloy developed for commercial application as an anode material for lithium ion batteries. Our alloy exhibits a stable capacity above 900 mAh g−1 after 50 cycles and a high coulombic efficiency of up to 99.7% during cycling. To enable a highly reversible nano-Si anode, melt spinning is employed to embed nano-Si particles in a Ti4Ni4Si7 matrix. The Ti4Ni4Si7 matrix fulfills two important purposes. First, it reduces the maximum stress evolved in the nano-Si particles by applying a compressive stress to mechanically confine Si expansion during lithiation. And second, the Ti4Ni4Si7 matrix is a good mixed conductor that isolates nano-Si from the liquid electrolyte, thus preventing parasitic reactions responsible for the formation of a solid electrolyte interphase. Given that a coulombic efficiency above 99.5% is rarely reported for Si based anode materials, this alloy's performance suggests a promising new approach to engineering Si anode materials.

Inhomogeneous microtexture evolution during the cold drawing process usually results in lean, sway, or sweep failure. The longitudinal fiber texture has higher stiffness than the texture and its proportion and distribution in the cross-section are critical for the bonding stability of fine gold wire. We investigated the inhomogeneous microtexture evolution of gold wire that was cold drawn through an asymmetric diamond die. In this study, the distributions of the and textures in a2 0μm diameter fine gold wire are the variables and their effects on the bonding stability of the wire were estimated by electron backscattered diffraction (EBSD) and finite element method (FEM) simulations. The use of a focused ion beam apparatus enabled a high quality of band contrast of the EBSD to be achieved in the exact half cross-sectional area of the fine gold wire. The detailed three-dimensional FEM results show that the asymmetric distribution of the textures plays a crucial role in increasing the spatial displacement of the gold bonding wire.

Thermosonic wire bonding is a well-known process which combines heat, ultrasonic energy and force to bond small wires to complete an electrical path from a metalized surface on a microchip to another metalized surface on the substrate of the circuit and the bonding occurs through the process of atomic diffusion. The bonding wire materials presently used in the industries are primarily gold (Au) and recently the use of low cost copper (Cu) and palladium coated wire (PdCu) have increased significantly. However, due to the increasing price of Au and reliability concerns with the Cu and PdCu wire has led to the search of alternative bonding wire materials in which silver (Ag) or silver alloy wire (Ag alloy) has emerged as the preferred choice. Cu and PdCu wire induces a higher stress on the bond pad and underlying structure due to its inherent hardness value. Ag has similar mechanical properties as Au while it's cheaper and has higher thermal and electrical conductivity as compared to Au. When compared to Cu, Ag is similar in conductivity, but softer in terms of mechanical properties. The pure Ag bonding wire has some issues such as unstable free air ball (FAB) shape and poor reliability. To overcome these issues, alloyed Ag wire (Ag-Au-Pd) was developed and their FAB formation, bondability and reliability were studied. The package used is BGA type and the pad composition is Al-1%Si-0.5%Cu. Ag alloy wire delivers good and stable bonding capability using nitrogen as ambient gas. Both the bonded ball and stich bonding show good bond integrity. The reliability is determined by the high temperature storage life test (HTSL) test. Intermetallic compound (IMC) growth behavior during reliability test is characterized by the scanning electron microscopy (SEM) and energy dispersive spectrometer analyses (EDS). Two types of IMCs Ag2Al and Ag3Al were observed. No failure or voids are observed in the bulk IMC or metal-IMC interface after the HTSL test at 150C for 1000 hrs. Additionally these IMCs are fabricated in bulk and their resistivity and co-efficient of thermal expansion (CTE) properties are characterized to understand the likely source of failure of the Ag-Al bond. The CTE of the Ag3Al is lower than the Ag2Alwhich could be attributed to the lower stretching of lattice constant of former at higher temperature. The interface between the Al and Ag2Al is likely source of crack generation and failure because of the high CTE difference between them. The resistivity of the Ag3Al phase was found to slightly higher than Ag2Al. The information regarding the properties of Ag-Al IMCs are important for the finite element and quantum mechanics based first principle calculation and to ultimately predict their behavior in real life situation. The Ag alloy wire show floor life time of minimum 10 weeks based on bonded ball shape, workability and bondability test and there is no visible appreciable degradation of pull strength and bonded ball shape overtime. Ag alloy wire bonding has the potential to become an emerging technology as an option in microelectronic packaging.

The rapidly solidified Si-xTiNi (x = 0.2-0.45) alloy ribbons were fabricated via melt spinning process. The thickness of the melt-spun ribbons was about 12.5 microm, and the sound section was selected for the experiment. The microstructures of the ribbons were analyzed using XRD, FE-SEM, and HR-TEM: The primary silicon particles of 30 nm-100 n min diameter were finely dispersed in the inactive buffering matrix of Si7Ni4Ti4 phase. The charge/discharge energy capacity and electrochemical properties were significantly influenced by the relative ratio of NiTi to silicon. With increasing the total amount of Ni and Ti content up to 45 at%, the amount of Si7Ni4Ti4 phase increased and the cycle performance was improved. The Si7Ni4Ti4 phase acted as a buffer for the volume expansion/contraction of Si occurring during the alloying and dealloying, and it could prevent a significant deterioration in cycle performance of the battery.

This paper presents the microstructures and electrochemical properties of Si-Ti-Ni alloys of various compositions prepared by a rapid solidification process. Si-15Ti-(0-25 at%)Ni alloy ingots prepared by arc-melting was melt-spun to produce thin strip of -15 Om thickness. The Si-Ni-Ti alloy electrode were fabricated by mixing the active powdered materials (88 wt%) with ketjen black (4 wt%) as a conductive material and polyamide-imide binder (PAI, 8 wt.%) dissolved in N-methyl-2-pyrrolidinone (NMP). Results showed that the microstructures of melt-spun Si-Ti-Ni ribbons consist of silicon, TiSi2, Si7Ni4Ti4, and NiSi2 phases depending on the composition. As the content of nickel increased in silicon matrix, TiSi2 phase disappeared while Si7Ni4Ti4 and NiSi2 phases are generated. The cycle efficiency of Si65Ti15Ni20 and Si60Ti15Ni25 alloys was significantly improved because of the increased volume fraction of Si7Ni4Ti4 and NiSi2 phases and fine particulated silicon phase.

The phase change due to varying content of titanium in Si-Ni-xTi alloys and its effect on the electrochemical behavior has been investigated. Specimens were prepared by melt-spinning to reduce the microstructure scale. Results showed that silicon particles of 50-100 nm diameter and dendrites of somewhat larger scale were formed in the Si-Ni-Ti alloys ribbons. The microstructure of Si70Ni15Ti15 alloy ribbons was composed of silicon particles finely dispersed in Si7Ni4Ti4 phase. The cycle performance was improved by the formation of TiSi2 or NiSi2 phase at the presence of Si7Ni4Ti4 phase, either of which combined with Si7Ni4Ti4 phase effectively accommodated the volume change of silicon particles during cycling. The reduced scale of silicon particles contributed to the enhanced cycle efficiency as well.

Recently, the application of Ag bonding wires in electronic devices has been attempted as alternative to Au bonding wires to reduce the material cost of Au. Nevertheless, Ag bonding wires have not been applied to devices due to interface corrosion problems between the Ag wire and Al pad during humidity reliability tests, such as the PCT (Pressure Cooker Test). As the technology for alloying Pd element in Ag wire has developed recently, the corrosive failure problem at the interface in the PCT has been improved significantly. This study examined the behavior of IMCs(intermetallic compounds) and interface corrosion between an Ag wire and Al metallization under humidity conditions (100%RH, 121'C). The chemical compositions of the Ag wires tested were pure Ag, Ag — 1wt%Pd and Ag-3%Pd. These wires are bonded to Al and noble metal(Au, Pd) metallization using a thermo-sonic bonder. The interfaces were characterized by FIB(Focused ion beam), HRTEM (High Resolution Transmission Electron Microscope) and EDS (Energy Dispersive X-ray Spectroscopy) The findings show that, (1) the interfacial reliability between the Ag wire and Ag metallization was improved considerably. The interface corrosion was suppressed significantly as the Pd content was increased. (2) Ag wires on a noble metal(Au, Pd) pad have stable reliability in PCT.

There have been many studies on replacing Au bonding wire with other bonding wire materials, because the cost of Au has dramatically increased by approximately 2~3 times in recent years. When replacing part of the bond pad with a noble metal, Ag bonding wire is of particular interest due to its superior electrical properties, lower cost and similar mechanical properties as compared with Au. Ag bonding wire is thermosonically bonded to 3 kinds of bond pad (Al, Au and Pd) and aged at high temperature (175°C). Then, the bondability and interface reactions are characterized at each bond pad. In the case of Ag-Al bonding, 2 kinds of intermediate phases were observed and the composition ratios of Ag and Al in these phases were 4:1 and 2:1, respectively. After 300 hrs of aging, cracks were formed in these intermediate phases and ball-lift failure occurred. However, in the case of the noble metal bond pad, a solid solution was formed between the Ag wire and bond pad and no voids or cracks were formed. This shows the robust bonding characteristics. The diffusion layer was observed and the diffraction pattern was analyzed by TEM (Transmission Electron microscopy). The Au-Al bond reliability was also characterized by a comparative study. In this study, Ag bonding wire is proposed as an alternative to Au bonding wire for noble metal pads. Also, the thermal reliability is reviewed and the failure mechanisms are verified with various bond pads.

To reduce material cost of Au bonding wire, Au-Ag alloy wire had been tried to use in electronic device, in alternative for Au wire. Nevertheless, Au-Ag alloy wire had not been applied to device due to failure problem during high humidity reliability test, like PCT(Pressure Cooker Test) for a while. Recently, as the technology adding Pd element to conventional Au-Ag was developed, corrosive failure problem at interface between wire ball and Al pad (metallization) was solved in PCT. Finally, mass production of Au-Ag-Pd wire starts to grow up. The study on reliability and behavior of intermetallic compounds(IMC) have not been performed in terms of thermal Aging or HTST(High Temperature Storage Life Test) yet. This study investigates IMC & voids behavior between Au-Ag-Pd wire and Al metallization under thermal aged condition (175'C). The chemical compositions of gold wires tested are 99.99% Au, Au-30wt.%Ag and Au-30wt.%Ag-5.5%wt.Pd, respectively. The wires are bonded on Al metallization by using thermosonic bonder, IMC behavior was characterized by FIB(Focused ion beam), TEM (Transmission Electron Microscope), EDS (Energy Dispersive X-ray Spectrometer) The findings reveal that, interfacial reliability between Au-Ag-Pd wire and Al metallization is considerably improved, compared with 4N Au or Au-30%Ag, Growth of IMCs as well as the voids formation are significantly suppressed.