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Article
Publication date: 2 January 2007

Narasimalu Srikanth

Wire bonding is an important method of interconnection in microelectronics. Ultrasonic energy is known to soften metallic materials and hence when used in the wire bond process it…

Abstract

Purpose

Wire bonding is an important method of interconnection in microelectronics. Ultrasonic energy is known to soften metallic materials and hence when used in the wire bond process it is effective to decrease the flow stress similar to thermal energy. The paper aims to address this issue.

Design/methodology/approach

Detailed resonance studies show that some designs have closeby resonance compared to the bonding frequency which causes enhanced vibration resulting in such over squashed bonds. Hence, precautions in the design stage are necessary to understand the closeby resonance frequencies and corresponding mode shapes of the leadframe that are in‐plane in nature along the transducer axis that can be excited by the capillary's motion. This can be determined a priori using numerical methods such as finite element method. In this paper, one such case study has been dealt in detail to explain the overall methodology.

Findings

To minimize the effects of resonance, damping should be increased by bonding polyimide tapes to enhance damping and stiffness which results in better ball bonds with optimum bell shape.

Originality/value

The paper explains the methodology of wire bonding in microelectronics.

Details

Microelectronics International, vol. 24 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 January 2008

Srikanth Narasimalu

Ultrafine feature sizes and high‐performance requirements have necessitated the integration of low‐k dielectrics with silicon‐level interconnects. These are mechanically weaker…

Abstract

Purpose

Ultrafine feature sizes and high‐performance requirements have necessitated the integration of low‐k dielectrics with silicon‐level interconnects. These are mechanically weaker than previous‐generation materials, a fact that has been recognized to be an industry wide issue. The inherently weaker nature of the low‐k dielectric material can pose significant challenges to downstream electronic‐packaging processes and materials. The purpose of this paper is to focus on the wire bonding of gold wires on a Cu/low‐k pad structure.

Design/methodology/approach

The paper presents a numerical model description and simulation procedure.

Findings

Numerical methods, particularly finite element method based simulations are a good tool to visualize and understand the reasons for success or failure during a bonding process. It enables one to relate the induced stress to the inherent bulk material's strength and interfacial strength. The results from such simulations clearly indicate the high‐stress locations and the amount of plastic strain that accumulates during the application of compressive force, heat and ultrasonic energy.

Originality/value

These simulations help to understand the device's weaknesses and correlate the failures so as to design the wire bonder equipment with better process control features.

Details

Microelectronics International, vol. 25 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 8 May 2009

Z.W. Zhong

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

Abstract

Purpose

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

Design/methodology/approach

Dozens of journal and conference articles published recently are reviewed.

Findings

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.

Research limitations/implications

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

Originality/value

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.

Details

Microelectronics International, vol. 26 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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