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The purpose of this paper is to review recent advances in fine and ultra‐fine pitch wire bonding.

Dozens of journal and conference articles published recently are reviewed.

The problems/challenges such as possible wire sweep and decreased bonding strength due to small wire sizes, non‐sticking, metal pad peeling, narrow process windows, wire open and short tail defects are analysed. The solutions to the problems and recent findings/developments in fine and ultra‐fine pitch wire bonding are discussed.

Because of the page limitation, only brief discussions are given in this paper. Further reading is needed for more details.

This paper attempts to provide an introduction to recent developments and the trends in fine and ultra‐fine pitch wire bonding. With the references provided, readers may explore more deeply by reading the original articles.

The purpose of this paper is to introduce a new method to model a stranded wire efficiently in 3D finite element simulations.

In this method, the stranded wires are numerically approximated with the Cauer ladder network (CLN) model order reduction method in 2D. This approximates the eddy current effect such as the skin and proximity effect for the whole wire. This is then projected to a mesh which does not include each strand. The 3D fields are efficiently calculated with the CLN method and are projected in the 3D geometry to be used in simulations of electrical components with a current vector potential and a homogenized conductivity at each time step.

In applications where the stranded wire geometry is known and does not change, this homogenization approach is an efficient and accurate method, which can be used with any stranded wire configuration, homogenized stranded wire mesh and any input signal dependent on time steps or frequencies.

In comparison to other methods, this method has no direct frequency dependency, which makes the method usable in the time domain for an arbitrary input signal. The CLN can also be used to interconnected stranded cables arbitrarily in electrical components.

This paper aims to analyze the effect of Au wire size and location of hook during wire pulling test to identify the variation of results obtained.

Two hook locations, namely, location A and location B were used to analyze the effect of hook location. Location A was the same as the hook location required by MIL-STD-883E standard, whereas location B was located near to the second bond. The correlation between new purposed failure modes and MIL-STD-883E standard was developed to reflect on the pull strength with the physical failure.

It was observed that fine pitch Au wire has higher variation and lower process capability of pull strength. Au wire pulled by the hook at location B provides a more representative result compared to that at location A. Fifty per cent or more of Au remnant is required to be considered as a good and reliable Au wedge bond based on the new purposed failure modes.

The evaluation of gold (Au) wedge bond requires a new proper wire pulling test method. This is due to the large variation obtained from the application of current practice of wire pulling test.

THE application of cemented wires to determine the location of initial failure in static tests on large specimens has been investigated, among others, by R. W. Powell in 1946.

The International Electronic Components Show in Paris in November, 1983, provided the occasion for a very successful meeting of ISHM‐France which attracted 170 attendees. The following presentations were given:

This paper attempts to review recent advances in wire bonding using copper wire.

Dozens of journal and conference articles published recently are reviewed.

The problems/challenges such as wire open and short tail defects, poor bondability for stitch/wedge bonds, oxidation of Cu wire, strain‐hardening effects, and stiff wire on weak support structures are briefly analysed. The solutions to the problems and recent findings/developments in wire bonding using copper wire are discussed.

Because of page limitation of the paper, only a brief review is conducted. Further reading is needed for more details.

This paper attempts to provide introduction to recent developments and the trends in wire bonding using copper wire. With the references provided, readers may explore more deeply by reading the original articles.

The purpose of this paper is to provide a systematic review on technical findings and discuss the feasibility and future of gold (Au) wirebonding in microelectronics packaging. It also aims to study and compare the cost, quality and wear-out reliability performance of Au wirebonding with respect to other wire alloys such as copper (Cu) and silver (Ag) wirebonding. This paper discusses the influence of wire type on the long-term reliability tests.

Literature reviews are conducted based on cost and wire selections of Au, Cu or Ag wirebonding. Detailed wear-out failure findings and wire selection with cost considerations are presented in this review paper. The future and the status of Au wirebonding in microelectronics packaging are discussed in this paper.

This paper briefly reviews selected aspects of the Au ball and other alternative bonding options, focusing on reliability performance, and discusses the future of Au wirebonding in the near future in semiconductor packaging.

The paper reveals the technical considerations when choosing the wire types for future microelectronics packaging.

The in-depth technical review and strategies of the selection of wire types (Au, Cu or the latest Ag alloy) in microelectronics packaging are discussed in this paper based on previous literature studies.

In this paper, reproduced by permission of “Metal Finishing” (New Jersey), the author enumerates the required properties of electroplated gold coatings on printed circuit boards and wire to ensure satisfactory bonding by ultrasonic means. The gold plating procedures and process control methods which are necessary to produce coatings yielding consistently high bond strengths are described.

Whereas the Minister of Labour (hereafter in this Order referred to as the “Minister”) has received from the Brush and Broom Wages Council (Great Britain) the wages regulation proposals set out in Schedules 1 and 2 hereof;

The purpose of this paper is threefold. First, an analytical model based on one-dimensional Dowell’s equation for computing ac-to-dc winding resistance ratio FR of litz wire is presented. The model takes into account proximity effect within the bundle and between bundle layers as well as the skin effect. Second, low- and medium-frequency approximation of Dowell’s equation for the litz-wire winding is derived. Third, a derivation of an analytical equation is given for the optimum strand diameter of the litz-wire winding independent on the porosity factor.

The methodology is as follows. First, the model of the litz-wire bundle is assumed to be a square shape. Than the effective number of layers in the litz wire bundle is derived. Second, the litz-wire winding is presented and an analytical equation for the winding resistance is derived. Third, analytical optimization of the strand diameter in the litz-wire winding is independent on the porosity factor performed, where the strand diameter is independent on the porosity factor. The boundary frequency between the low-frequency and the medium-frequency ranges for both solid-round-wire and litz-wire windings are derived. Hence, useful frequency range of both windings can be determined and compared.

Closed form analytical equations for the optimum strand diameter independent of the porosity factor are derived. It has been shown that the ac-to-dc winding resistance ratio of the litz-wire winding for the optimum strand diameter is equal to 1.5. Moreover, it has been shown that litz-wire winding is better than the solid-round-wire winding only in specific frequency range. At very high frequencies the litz-wire winding ac resistance becomes much greater than the solid-round-wire winding due to proximity effect between the strands in the litz-wire bundle. The accuracy of the derived equations is experimentally verified.

Derived equations takes into account the losses due to induced eddy-currents caused by the applied current. Equations does not take into account the losses caused by the fringing flux, curvature, edge and end winding effects.

This paper presents derivations of the closed-form analytical equations for the optimum bare strand diameter of the litz-wire winding independent on the porosity factor. Significant advantage of derived equations is their simplicity and easy to use for the inductor designers.