Wire Sag Research Articles

The wire sag problem in wire bonding technology for semiconductor packaging

Driven by the smaller, faster and cheaper demands of advanced microelectronic devices, the modern packages are required to increase I/O numbers, reduce die and package sizes and lower manufacturing costs. Although, today’s microelectronic devices have many modern types of package, e.g. flip chip, wafer level packaging and tape automated bonding technologies, wire bonding is still the dominant microelectronic packaging technology.To provide more functions within a package, the 3-dimensional and multi-chip modules have come to be the solution of choice in delivering higher integration, smaller and more functional products for meeting consumer requirements, especially in the portable and handheld electrical products.Since the interconnection distance of the multi-chip modules is usually longer than that of a single-chip system, concerns about wire sweep and wire sag for the applications of 3-dimensional packaging technology in the multi-chip module systems have been highly mentioned recently.This has been ascertained by the author in previous studies, the longer the bond length and the higher the bond height of a wire bond, the smaller the sweep stiffness of the bond system becomes. The lower sweep stiffness of the wire bond will always cause higher risk of wire sweep. Consequently, for 3-dimensional and multi-chip packaging, excessive wire sag can lead to wire touch in the lower layer and thereby causing short circuits and malfunction of chips.Wire sag problems are very crucial to the applications of 3-dimensional and multi-chip packaging in semiconductor industry. To authors’ knowledge, this issue has never been investigated. The main purpose of this paper will be to study in depth the wire sag problem for long wire bonds, applied in 3-dimensional and/or in multi-chip module packaging. A definition of the sag stiffness of a wire bond will be shown to represent sag resistance of specific profiles of wire bond. The author will also present wire sag experiments of wire bonds thereby verifying numerical analysis.

Hierarchical Transformation of Silver Morphologies on Clay Film from Spheres, Cubes, Rods to Lengthy Nano-Wires

ABSTRACTSilver nanoparticles (AgNPs) in silicate clay matrix films were fabricated from solution casting method. The Ag/clay dispersion was first prepared from in situ reduction of silver nitrate in the presence of silicate clay platelets and ethanol as the reducing agent. The morphologies of AgNPs have changed in a hierarchical manner, from sphere to cube and then to rod and wire morphologies during the annealing at 200 °C. The originally homogeneous AgNPs distribution in the clay matrix underwent the transformation of AgNPs in moving to the film surface and coalescing to larger sizes. The hierarchical change continued to form other morphologies. We observed the self-assembled morphologies including spherical (diameter ∼ 50 nm), cubic (length ∼100 nm), rod-like (length ∼ 1.6 μm and width ∼300 nm) and then to lengthy wire Ag (length ∼10μm). The kinetic mobility of AgNPs to surface and the characterization of Ag composition were confirmed through energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD).

2A2-A25 ワイヤ弛みを考慮したパラレルワイヤ懸垂ロボットの動力学計算法

A parallel wires driven mechanism realizes a positioning device with a simple and light mechanism using multiple wires. The large scale parallel wire mechanism, however, generates wire's sag which makes difficult to control a suspended object precisely. For an analysis, an accurate simulation and a precise control of the large scale parallel wire mechanism, a dynamics calculation method is required. This study proposes the dynamics calculation method for the large scale parallel wire mechanism considering the sag of wires. One method is based on a finite element modeling of the wires. The model becomes a differential algebraic equation. Another one is a combination method of a quasi-static model of wires and a dynamical model of the suspended object. It is shown that both models can represent the sway and the sag of wires and the later one is more efficient and practical for the dynamics calculation.

BESIII track fitting algorithm

A track fitting algorithm based on the Kalman filter method has been developed for BESIII of BEPCII. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity of magnetic field (NUMF) and wire sag, etc., have been carefully handled. This algorithm works well and the performance satisfies the physical requirements tested by the simulation data.

Large precision muon detector for ATLAS

Abstract The ATLAS muon spectrometer is designed to exploit the full physics discovery potential at the Large Hadron Collider in a stand-alone mode. The precision muon detector is made of monitored drift tubes with tracking precision better than 50 μm to measure the muon track sagitta in the toroidal magnetic field. A world-wide intensive construction work of the ATLAS muon detector is under way. We report the precision muon detector mass production experience, including the R&D results on the long tube operation stability and the impact on the momentum resolution due to wire sag. The quality control data in mass production are presented. Cosmic ray test results show that the MDT chambers have tracking efficiency close to 100% and single wire resolution is better than 80 μm .

Experience on the operation of the 2-in-1 electromagnetic undulator of FELICITA-I

The 5m-Undulator of FELICITA I has been installed at the final position in the storage ring DELTA in spring 95. Detailed magnetic measurements have been performed in place to get a complete characterization of this device in both possible modes, pure undulator and optical klystron mode, respectively. The undulator consists of 38 identic poles. Four power supplies are connected to the main coils. Three of them drive the central six poles to get the dispersive section with its matching to the outer undulator sections. This setup allows a change between the optical klystron and the pure undulator mode without changing the hardware. For measuring the magnetic field components a hall-probe was used. It was found that correction coils for compensating peak field variations were not necessary, because of errors less then 0.2 %. Only for the purpose of steering correction coils had to be used. The field integrals were also measured with the pulsed-wire technique. For fast response concerning the matching, in particular of the dispersive section this technique was found to be very useful. Because of the large period length of 25 cm the wire sag in the rather long undulator could be neglected.

Drift tube wire tension monitoring

The characteristic frequency of vibration of a drift tube anode wire may be determined using electrostatic excitation and circuits sensitive to the variation of wire capacitance. We compare test results with various excitation conditions to a electromechanical response model. The circuits and analysis are generally applicable to in situ monitoring of wire sag and tension in long drift tubes and in multi-wire proportional chambers.

Wire method for magnetic field measurements in long undulators

This paper is devoted to improvements of the conventional version of the pulsed wire method used for operative magnetic field control. The aim was to avoid some serious disadvantages: signal reflections from the wire ends which prevent accurate measurements, the sag of the wire which leads to wire deflection from a straight line, and complexity of the used wire-position detectors. An effective and simple wire-position detector providing accuracy up to 1 μm was designed and tested. Damping of reflected signal noise and decrease of the wire sag were achieved. It is shown that with these improvements the wire method can be applied to undulators with a length up to several meters.

Gravitational wire sag in nonrigid drift chamber structures

In the design of drift chambers, the end plate for the chambers have generally been of simple geometries and of high stiffnesses. When end plates have to be as light and as thin as possible to conserve weight and space, the result will be flexible end plates. This article investigates the sag behavior of wires in the drift chamber as the relatively compliant end plates more relative to each other. An analytical expression relating gravitational sag to end plate motion is derived. Experimental results are also compared to the theoretical predictions on gravitation sag as a function of end plate motion. Some concepts to solving problems that arise due to such motion are also discussed.

Constant-tension thermocouple rake suitable for use in flame mode combustion studies

An improved design for a thermocouple rake configuration to be used in fundamental combustion studies is presented. Experience with the constant-tension thermocouple rake has nearly eliminated thermocouple sensing wire sag which is common using conventional rake configurations.

Railway Overhead Contact Systems, Catenary-Pantograph Dynamics for Power Collection at High Speeds

A program has been prepared for the GE-625 computer in Fortran IV language to compute the dynamic behavior of a catenary and pantograph for railroad cars moving at constant velocity. The catenary is considered to consist of two wires joined by elastic droppers at arbitrary locations. The upper catenary wire is in turn supported by elastic towers at arbitrary locations. Account is taken of: Tension and mass in each wire; wire sag; damping of the wires; springing between shoe and wire; springing and damping between shoe and pantograph frame; damping of the pantograph frame to the railway car; lifting of the wire away from the shoe; and stops in the pantograph to limit motion between shoe and pantograph frame. Up to eight arbitrarily spaced pantographs can be included, with as many as sixty droppers and ten towers. Force at up to ten droppers can be printed as a function of time. The additional output is catenary deflection and forces and deflections of the pantographs. Results are presented for some interesting variations of the system constants.

Wooden Lattice Masts

For radio work, the use of wooden guyed structures is advocated on the grounds that they are inexpensive and suited to the doubtful permanency of some radio stations. The horizontal pull of the antenna at the top of the masts is assumed to be about 14,000 kg. (30,000 lbs.); thus taking account of wind pressure, ice covering of the antenna wires, and the tension due to elimination of wire sag. The antenna should be guyed at a number of points to avoid long spans with high stresses due to beam and column action. The use of many light guys is advisable because of the difficulty of breaking up heavy guys by insulators. The position of the anchorages is determined by considerations of guy economy and of value of surrounding land. In calculating wind stresses, an assumed wind load on the masts of 200 kg. per sq. meter (40 lbs. per square foot) is used; and about 0.8 to 0.9 of the mast surface is regarded as effective in opposing the wind. The load at the center of each span is equal to the dead weight of the masts above added to the stresses due to beam and long column action. This load enables calculating the cross section of the masts. For masts up to about 100 meters (300 feet) high it is recommended to use only one size of timber to avoid complication. Above that height, a second lighter timber may be used.