Coated Silver Wire Research Articles

A Review of Silver Wire Bonding Techniques.

The replacement of gold bonding wire with silver bonding wire can significantly reduce the cost of wire bonding. This paper provides a comprehensive overview of silver wire bonding technology. Firstly, it introduces various types of silver-based bonding wire currently being studied by researchers, including pure silver wire, alloy silver wire, and coated silver wire, and describes their respective characteristics and development statuses. Secondly, the development of silver-based bonding wire in manufacturing and bonding processes is analyzed, including common silver wire manufacturing processes and their impact on silver wire performance, as well as the impact of bonding parameters on silver wire bonding quality and reliability. Subsequently, the reliability of silver wire bonding is discussed, with a focus on analyzing the effects of corrosion, electromigration, and intermetallic compounds on bonding reliability, including the causes and forms of chlorination and sulfurization, the mechanism and path of electromigration, the formation and evolution of intermetallic compounds, and evaluating their impact on bonding strength and reliability. Finally, the development status of silver wire bonding technology is summarized and future research directions for silver wire are proposed.

Distribution of Coated Metal Layer on Free Air Ball (FAB) Surface

Abstract Developments in bonding wire focus on coated silver wire for stacked devices in memory sectors revealing near equivalent performances to 4N Au wire. In addition to stacked device applications, the wire is also examined for other conventional applications. The innovative wire exhibits excellent performance on biased Highly Accelerated Stress Test (bHAST) passing 192h and 504h at 130°C, 85%RH for +3.3V and +20V, respectively. Thus, the wire satisfied one of the important criteria required to pass automotive reliability test (2X stress test, AEC Q100 Rev-H, with limited test samples). The test is conducted using 0.8mil coated silver wire and molded with green epoxy molding compound. Another benefit of the wire is stitch bond bondability with high MTBA of greater than 2h.

Growth of Intermetallics at Coated Silver Wire Bond Interfaces

Abstract The newly developed gold (Au) coated silver (Ag) wire exhibits axi-symmetrical free air ball (FAB) formation under atmosphere similar to Au wire. FAB of coated Ag showed better corrosion resistance than FAB of alloyed Ag, as Au dissolved along the periphery of Ag FAB forming into a solid-solution, Ag-Au alloy. Composition of the solid-solution Ag-Au alloy along the periphery ranges between 10 and 28wt% of Au. The diffusion depth of Au is 4μm from surface towards the center of FAB. For precise measurement of the diffusion length of Au into Ag, a solid thin layer is been parted using focus-ion beam (FIB). The solid thin layer is further thinned down to observe in Transmission Electron Microscope (TEM) and analyzed using line scan energy dispersive X-ray analysis (EDX) attached to it. Near the neck of FAB and wire, Au diffusion is high up to 58wt%. On thermal ageing at 150/175°C for 500/1000h, the coated Ag wire bonded to Al-0.5wt%Cu pad revealed no degradation on ball pull/shear. Bond interface revealed significant growth of silver aluminide (AgAl) to a thickness of 3μm for 1000h of ageing and the growth rate fits to square-root power law.

Design and construction of new potentiometric sensors for determination of Al3+ ion based on (Z)-2-(2-methyl benzylidene)-1-(2,4-dinitrophenyl) hydrazine.

(Z)-2-(2-methyl benzylidene)-1-(2,4-dinitrophenyl) hydrazine (L) was used as an active component of PVC membrane electrode (PME), coated graphite electrode (CGE) and coated silver wire electrode (CWE) for sensing Al(3+) ion. The electrodes exhibited linear Nernstian responses to Al(3+) ion in the concentration range of 1.0×10(-6) to 1.0×10(-1)M (for PME, LOD=8.8×10(-7)M), 5.5×10(-7) to 2.0×10(-1)M (for CWE, LOD=3.3×10(-7)M) and 1.5×10(-7) to 1.0×10(-1)M (for CGE, LOD=9.2×10(-8)M). The best performances were observed with the membranes having the composition of L:PVC:NPOE:NaTPB in the ratio of 5:35:57:3 (w/w; mg). The electrodes have a response time of 6s and an applicable pH range of 3.5-9.1. The sensors have a lifetime of about 15weeks and exhibited excellent selectivity over a number of mono-, bi-, and tri-valent cations including alkali, alkaline earth metal, heavy and transition metal ions. Analytical utility of the proposed sensor has been further tested by using it as an indicator electrode in the potentiometric titration of Al(3+) with EDTA. The electrode was also successfully applied for the determination of Al(3+) ion in real and pharmaceutical samples.

Mass Production of Source Core for Iodine-125 Seed

Nowadays, brachytherapy using a sealed source called a ‘seed’ has drawn attention for the treatment of various cancers. Generally, Iodine-125 (I) has been used for the seed in the radiation therapy of eye disease and prostate cancer. I has a half-life of 59.4 days, and emits 27 keV and 31 keV X-rays, and a 35 keV γ-ray through an internal conversion process. An I seed of 4.5 mm (l) × 0.8 mm (O) has a structure composed of an inner source core and an outer shell capsule. I is adsorbed on the source core’s surface and a titanium capsule surrounds it. The seed is directly inserted into the human body to treat cancer cells, and the seed may be permanently left in tissues owing to the low activity and the excellent biocompatibility of Ti capsule (Fig. 1). The diverse materials and preparation of the source core have been reported for many years, for example, a palladium (Pd) coated silver wire, a silver (Ag) rod and a porous ceramic tube etc. The Korea Atomic Energy Research Institute (KAERI) previously used a bare ceramic rod and an Ag+Al2O3 rod 12 as the core. With regard to the preparation of an I seed, the electro deposition technique was used for adsorption of iodine on the silver surface. In addition, a chemical adsorption on the Pd coated silver wire, the impregnation into ceramics and iodine substitution after forming an intermediate having chloride (Cl) or bromide (Br) were reported. In our previous investigation, the effect of the various intermediates (N3 −, CO3 , C2O4 , AsO4 , Cl− and PO4 ) using each set of 10 Ag rods were reported. Among them, Ag rods modified using phosphate (PO4 ) showed the highest adsorption ability with the good substitution effect of iodine. On the basis of this technique, the studies on mass production using 100 Ag rods and leachability test of a finished source core prior to encapsulation were performed in this work. The uniformity of iodide adsorption on every silver rod in the same batch is important for mass production to reduce the number of abandoned rods. For this reason, we developed a cutting device (Fig. 2) precisely manufacturing the silver rods in 3 mm (l) and compared the iodide adsorption with the handmade rods. A silver wire of 0.5 mm (O) passes through a syringe needle (d) of 0.584 mm (O), and the wire is softened through the heating part (b). The length of this wire is adjusted with the help of micrometer (c) and can quickly cut to a uniform shape by using a steel blade (a). In the case of handmade rods, the wire was cut by using scissors, and both ends were manually polished with sandpaper.

Development of novel potentiometric sensors for determination of tartrazine dye concentration in foodstuff products

Tartrazine dye Na3TZ in foodstuff products was determined by a new modified carbon paste electrode, encoded sensor A, and a coated silver wire electrode, encoded sensor B, based on tartrazine TZ- cetryltrimethyl ammoniumbromide CTAB as a chemical modifier TZ-CTA. The electrodes exhibit the following characteristics listed respectively: a Nernstian slope of 17.9±0.5 and 19.4±0.2mV/decade for tartrazine ion over a wide concentration range from 4.3×10−7 to 1.0×10−2 and 1.1×10−7 to 1.0×10−2M. The lower detection limits: 3.2×10−7 and 5.5×10−8M. Short response time (5–8s) over the pH range 3.8–7.7 and 4.2–8.1. The proposed sensors display significantly high selectivity for TZ ion over a wide variety of sugars, some anions, common organic, inorganic compounds and additives. The developed electrodes were applied to the potentiometric determination of tartrazine ion in different kinds of foodstuffs: solid jelly (strawberry and custard) powder samples and soft drink (orange) samples with satisfactory results.

Adsorption of 125I on palladium coated silver wire

The adsorption of 125I on palladium coated silver wires was studied in this paper. The experimental conditions, e.g., reaction volume, carrier concentration, reaction time, reaction temperature, pH of the reaction mixture, were systematically optimized to obtain quantitative adsorption of 125I on palladium coated silver wires. The experiments were performed using potassium iodide 8–9 μg as carrier in a reaction volume of 100 μL incubated in ~50 °C water bath for ~1 h, and the pH of the reaction system was controlled at 2–2.5. The distribution of activity on palladium coated silver wire was uniform, and the source cores can be easily sealed by laser welding into titanium capsules.

Novel PVC-membrane potentiometric sensors based on a recently synthesized sulfur-containing macrocyclic diamide for Cd 2+ ion. Application to flow-injection potentiometry

A new sulfur-containing macrocyclic diamide, 1,15-diaza-3,4,12,13-dibenzo-5,11-dithia-8-oxa-1,15-(2,6-pyrido)cyclooctadecan-2,14-dione, L, was synthesized, characterized and used as an active component for fabrication of PVC-based polymeric membrane (PME), coated graphite (CGE) and coated silver wire electrodes (CWE) for sensing Cd 2+ ion. The electrodes exhibited linear Nernstian responses to Cd 2+ ion in the concentration range of 3.3 × 10 −6 to 3.3 × 10 −1 M (for PME, LOD = 1.2 × 10 −6 M), 2.0 × 10 −7 to 3.3 × 10 −1 M (for CWE, LOD = 1.3 × 10 −7 M) and 1.6 × 10 −8 to 1.3 × 10 −1 M (for CGE, LOD = 1.0 × 10 −8 M). The CGE was used as a proper detection system in flow-injection potentiometry (FIP) with a linear Nernstian range of 3.2 × 10 −8 to 1.4 × 10 −1 M (LOD = 1.3 × 10 −8 M). The optimum pH range was 3.5–7.6. The electrodes revealed fairly good discriminating ability towards Cd 2+ in comparison with a large number of alkali, alkaline earth, transition and heavy metal ions. The electrodes found to be chemically inert, showing a fast response time of <5 s, and could be used practically over a period of about 2–3 months. The practical utility of the proposed system has also been reported.

Supported bilayer lipid membranes modified with a phosphate ionophore

This article reports the electrical responses of a phosphate ionophore, the cyclic polyamine 3-decyl-1,5,8-triazacyclodecane-2,4-dione (N3-cyclic amine) incorporated into metal supported bilayer lipid membranes (s-BLM). Teflon coated silver wire was used as a support. In a potentiometric mode, the ionophore had a response that was linearly related to the logarithm of HPO4(2-) concentration and was also dependant on pH. Selectivity coefficients for other anions compared to HPO4(2-) ions, determined by the separate solution method, fell within the range 1.73 x 10(-4) to 6.38 x 10(-2).

Diffusion Coefficients of Redox Probes Encapsulated within Sol−Gel Derived Silica Monoliths Measured with Ultramicroelectrodes

The diffusional mobilities of potassium ferricyanide (Fe(CN)63-) and ferrocene methanol (FcCH2OH) encapsulated within silica monoliths have been investigated using cyclic voltammetry and chronoamperometry at an ultramicroelectrode. In this work, a 13-μm-radius Pt microdisk working electrode and a silver chloride coated silver wire (r = 0.5 mm) reference electrode were inserted into doped silica sols prepared by the sol−gel process. The resultant gels were aged and slowly dried under a relative humidity atmosphere of 60−70% to minimize gel cracking. Fast-scan voltammetry (up to 100 V/s) confirmed that the gel−electrode interface remained intact throughout the duration of the drying period (typically 20−50 days). During this time frame, an ca. 30% loss in mass and ca. 50% reduction in volume of the gels were observed. The diffusion coefficients of gel-encapsulated Fe(CN)63- and FcCH2OH were measured without prior knowledge of dopant concentration via normalization of the chronoamperometric response with the steady-state limiting current obtained from a 2 mV/s potential sweep. For gel-encapsulated FcCH2OH, the diffusion coefficient dropped from ca. 4 × 10-6 cm2/s to less than 0.6 × 10-6 cm2/s as the gel dried, whereas for gel-encapsulated Fe(CN)63-, a near constant value of 2 × 10-6 cm2/s was obtained. These results suggest that transport in these solids is influenced by both gel structure and by the nature of the entrapped reagent.

Comparison of five membrane electrode designs and a study of poly(vinyl chloride) membranes with monoaza crown ethers

Five electrode designs based on PVC and silicone-rubber membranes are compared. The responses of conventional electrodes, a coated silver wire and a coated carbon rod, to potassium ion were tested with valinomycin as model ionophore. A laboratory-made PVC electrode was found to be particularly useful for testing new membranes. Five of the six plasticizers studied were found to respond in near-Nernstian fashion to alkali metal ions. Of the six monoaza crown ethers tested as ionophores, only one improved the alkali metal response of the PVC membranes in neutral solution. The reason for this is discussed.