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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.

The purpose of this paper is to provide a systematic method to perform long‐term reliability assessment of gold (Au) and copper (Cu) ball bonds in fineline ball grid array package. Also with the aim to study the apparent activation energies (E_aa) and its associated wearout mechanisms of both Au and Cu wire in semiconductor device packaging. This paper discusses the influence of wire type on the long‐term reliability and mechanical performance after several component reliability stress tests.

A fineline ball grid array (FBGA) package with Cu and Au wire bonds was assembled with green molding compound and substrate. Samples are subjected for long‐term high temperature storage bake test at elevated temperatures of 150°C, 175°C and 200°C. Long‐term reliability plots (lognormal plots) are established and E_aa of both ball bonds are determined from Arrhenius plots. Detailed failure analysis has been conducted on failed sample and HTSL failure mechanisms have been proposed.

Reliability results show Au ball bond in FBGA package is observed with higher hour‐to‐failure compared to Cu ball bonds. The E_aa value of high temperature storage life (HTSL) reliability for Au ball bond is lower than Cu ball bond. Typical HTSL failure mechanism of Au ball bond is induced by micro‐voiding and AuAl intermetallic compound (IMC) micro‐cracks while CuAl IMC micro‐cracking (induced by Cl⁻ corrosion attack and micro‐cracking) caused wearout opens in Cu ball bond. These test results affirm the test‐to‐failure data collected is a useful method for lifetime prediction and E_aa calculation.

The paper reveals higher reliability performance of Cu ball bond in FBGA flash memory package which can be deployed in flash memory FBGA packaging with optimised package bill of materials.

The test‐to‐failure methodology is a useful technique for wearout reliability prediction and E_aa calculation.

The realization of thick‐film circuits on glass substrates is discussed. Within the large number of commercially available thick‐film pastes, suitable pastes for thick‐film conductors, resistors and dielectrics on glass substrates have been found. Experimental results for these pastes are presented. Finally two applications for thick‐film on glass technology are demonstrated.

An overview of the concerns involved in the operation of electronic hardware at elevated temperatures is presented. Materials selection and package design issues are addressed for a wide range of packaging elements from the semiconductor chip to the box. It is found that most elements of common high density device and packaging architecture can be used up to 200°C. However, gold‐aluminium wirebonds, eutectic tin‐lead solder joints and die attaches, and FR‐4 boards will seriously degrade at temperatures below 200°C. For these elements, alternative materials of construction are recommended. Comparisons are made between package design for high power dissipation and that for high temperature operation.

Knowledge of critical materials and process parameters necessary to fabricate quality copper thick film multilayer and hybrid circuits is being amassed and distributed throughout the industry via technical reports and presentations. Generally the information being provided in a single report deals with specific segments of the industry or only one or two specific nitrogen fireable materials. In order for hybrid manufacturers to commit themselves to the technology they need to know that sufficient flexibility exists to permit design of complex circuits and accommodate circuit design changes without imposing changes in basic process guidelines and controls. The OEM's concern, which is valid, has been that the investment required for capital equipment and establishing new processes must be fully supported by and provide reasonable return from the technology being initiated. This paper introduces new information on wire bonding in copper thick film circuits and some improvements in nitrogen fireable resistor characteristics and processing. Materials are available to produce a broad range of circuits without varying basic process parameters, and adding wirebonding as an interconnect capability further expands the circuit complexity and density achievable with copper thick films.

Today’s emerging markets in the electronic packaging industry require some unique properties in adhesives, especially in die attach applications. In multichip module (MCM) applications, for example, the low temperature reworkability of die bonds is of primary importance, particularly if known good die (KGD) are not employed. If KGD are used in the MCM, a temporary, reworkable die adhesive is also desirable for a KGD testing programme. Large area die on organic substrates, which are key to the more portable, high power computers, require a very compliant adhesive to absorb the high mismatch in expansions. An overview of the present adhesive technologies reveals some serious limitations in their application and performance. Traditional Ag epoxies, primarily because of their irreversible ‘thermosetting’ during cure, do not fulfill all the material requirements. Thermoplastic chemistries are ideal candidates for MCMs because of their reversible melting and resolidification properties. This paper details the development of a novel silver loaded thermoplastic paste that overcomes most of the deficiencies seen in present day adhesives. One of the main obstacles that has hindered the use of thermoplastic pastes as an adhesive has been the slow solvent extraction during the curing step. With current technology, this inherently slow solvent extraction typically requires a complex process of first depositing a flat profile, then removing the solvent with a pre‐drying step, and finally attaching the die by a heat/pressure step. A blend of components, hereafter referred to as DM4030, has been tested and compared against conventional materials in the industry. Functional properties of adhesion, resistivity, wire bonding and others are summarised for various temperature profiles. Long‐term reliability test results are shown for temperature cycling, temperature/humidity (85° C, 85% RH), and high temperature storage. For reworkability applications, die removal force as a function of temperature is also presented.

This paper gives a popular introduction to thin film and some reasons for using this technology. The miniaturisation techniques at Brel & Kjaer are described and the background for the work with thin film techniques is given. The company's method of realising thin film circuits is described by going through the resistor materials, resistor design and photolithography and etching steps. The kind of equipment needed and what B & K use to make prototypes and small scale production are shown. TCR‐values and the resistor stability after 10,000 hours at different environmental exposures are given. Examples of applications with single layer and double layer structures are shown. A thick film circuit is transformed to thin film, and the size reduction can be seen. Finally, for this circuit, the cost calculations are stated for both versions.

The driving forces behind recent significant improvements in organic packages for microelectronic applications are electrical performance, product weight, size and manufacturing cost. A very careful selection of optimum manufacturing processes, equipment and materials, and stringent control of critical manufacturing operations are prerequisites for success in this emerging market place. Major technical and business related challenges to a printed circuit board manufacturer who plans to enter this market are discussed.

The ageing behaviour of aluminium wire bonds (Al‐1%Si wire, 25 µm diameter) on five different gold thick film inks from three different manufacturers has been investigated. A new mechanism, the oxidation of the gold‐aluminium intermetallics, is proposed to explain the degradation of contact resistance for this system. With this theory the degradation of bond resistance, as well as the ‘healing effect’, can be explained. The oxidation can be proven by ageing in a vacuum. Surface analytical methods have shown the compound Au4Al to be responsible for the oxidation.

A family of cavity‐down plastic ball grid array (PBGA) packages have been designed by split via connection (SVC) and split wrap around (SWA) methods. Because of the special designs, these packages consist of a single core of organic material and two‐metal layers of copper and are manufactured with the conventional printed circuit board (PCB) process at very low cost. The electrical performances of the packages are studied by both numerical simulations and experimental measurements. Parasitic parameters are extracted from time domain reflectometer (TDR) and time domain transmission (TDT) measurements. Cross‐talk and simultaneous switch output (SSO) noise of the packages are also investigated.