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Article
Publication date: 3 April 2018

Yow-Ching Liaw, Shou-Yen Chao and Jung-Hua Chou

The purpose of this paper is to determine the key process factors which affect the adhesion strength of encapsulation molding compounds (EMCs) to leadframes to obtain reliable…

Abstract

Purpose

The purpose of this paper is to determine the key process factors which affect the adhesion strength of encapsulation molding compounds (EMCs) to leadframes to obtain reliable components without any need to pretreat the leadframe surface.

Design/methodology/approach

EMCs were molded to Cu leadframes to experimentally quantify the effect of mold temperature, resin viscosity, leadframe oxidation and powder moisture on the adhesion force. Component reliability was assessed by PCT.

Findings

A higher mold temperature result in a larger adhesion force. The mold temperature of 175°C provides the largest process window. Leadframe oxidation can increase adhesion first, but then decrease it drastically with further oxidation. The powder moisture content has mixed effect on adhesion.

Practical implications

By molding at 175°C, limiting the wire bonding time and minimizing the powder moisture content, reliable components can be obtained without any need for leadframe surface pretreatment such as plasma cleaning or surface coating.

Originality/value

Quantify the key process factors which affect the adhesion of EMCs and reveal reason behind the current industrial practice of using the mold temperature of 175°C.

Details

Microelectronics International, vol. 35 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 6 February 2017

Balázs Illés, Barbara Horváth, Attila Géczy, Olivér Krammer and Karel Dušek

The aim of this paper is to present a review of the tin whisker growth phenomena. The study focuses mainly on whisker growth in a corrosive climate when the main inducing factor…

Abstract

Purpose

The aim of this paper is to present a review of the tin whisker growth phenomena. The study focuses mainly on whisker growth in a corrosive climate when the main inducing factor of the whisker growth is oxidation. The tin whisker phenomenon is still a big challenge in lead-free reflow soldering technology. Modern lead-free alloys and surface finishes with high tin content are considered to be possible sources of whisker development, also the evolution of electronic devices towards further complexity and miniaturization points to an escalation of the reliability risks.

Design/methodology/approach

The present work was based on a worldwide literature review of the substantial previous works in the past decade, as well as on the results and experience of the authors in this field.

Findings

The effect of corrosion on tin whisker growth has been under-represented in reports of mainstream research; however, in the past five years, significant results were obtained in the field which raised the corrosion phenomena from being a side effect category into one of the main inducing factors. This paper summarizes the most important findings of this field.

Practical implications

This literature review provides engineers and researchers with a better understanding of the role of corrosion in tin whisker growth and the current challenges in tin whisker mitigation.

Originality/value

The unique challenges and future research directions about the tin whisker phenomenon were shown to highlight rarely discussed risks and problems in lead-free soldering reliability.

Details

Soldering & Surface Mount Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 September 1999

Chonglun Fan, Joseph A. Abys and Alan Blair

Palladium surface finishes are utilized on leadframes, printed wiring boards and automobile sensors. Their superior functional performance and the considerable environmental…

Abstract

Palladium surface finishes are utilized on leadframes, printed wiring boards and automobile sensors. Their superior functional performance and the considerable environmental impact of plating lead‐free finishes for packaging processes have been increasingly recognized by the electronic industry. Wire bondable and solderable palladium finishes meet military and industrial standards at no extra cost in the overall assembly processes when compared to traditional packaging techniques. In addition to the development of palladium plating chemistries and technologies, the functional properties of the surface finishes including their wire bonding performance have also been investigated at Bell Laboratories. In this study, gold and aluminum wire bonding to palladium finishes was tested and the wire bond pull force and break position were examined in order to optimize the bonding processes. The results of the study are reported in this paper.

Details

Circuit World, vol. 25 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 December 2001

M.R. Harrison, J.H. Vincent and H.A.H. Steen

Results for reflow soldering are presented from a three‐year EC funded project “IDEALS” to develop lead‐free soldering solutions. On the basis of fundamental data from the…

3488

Abstract

Results for reflow soldering are presented from a three‐year EC funded project “IDEALS” to develop lead‐free soldering solutions. On the basis of fundamental data from the literature, a shortlist of candidate lead‐free solders was selected, and results from tests on physical and soldering characteristics, and wetting balance testing, led to the choice of SnAg3.8Cu0.7, melting at 217°C. Implications for solder paste medium development are discussed. Differences in alloy density, melting point, and surface tension relative to conventional solders were found to give higher levels of internal voids, reduced spread on copper, and rougher, duller joints. Reflow process window studies showed that sound reliable joints could be obtained with a peak temperature as low as 225°C. Reliability was tested on soldered test boards using thermal shock cycling, power cycling, and vibration. Overall the SnAg3.8Cu0.7 gave results approximately equivalent to conventional solders, and different board finishes had no significant effect. The effects of Sb and Bi were also evaluated. No justification was found for minor additions of Sb, but 2‐5 per cent Bi was found to allow a reduction of the peak reflow temperature, though at the cost of reduced reliability if any Pb was present.

Details

Soldering & Surface Mount Technology, vol. 13 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 December 1996

F.P. McCluskey, L. Condra, T. Torri and J. Fink

An overview of the concerns involved in the operation of electronic hardware at elevated temperaturesis presented. Materials selection and package design issues are addressed for…

863

Abstract

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.

Details

Microelectronics International, vol. 13 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 January 1994

J. Falk, J. Hauke and G. Kyska

Although wire‐bonding is an established and well‐known technique for micro‐joining on leadframes, direct die‐attach without housing on printed circuit boards has some new…

Abstract

Although wire‐bonding is an established and well‐known technique for micro‐joining on leadframes, direct die‐attach without housing on printed circuit boards has some new requirements for the surface of the bond pads and the PCB itself. The best choice of material for the bond pads is a pure gold metallisation. The quality of the surface can be tested during wire‐bonding using the ultrasonic‐power process window. It will be shown that the surface and the PCB itself have a considerable influence on the ultrasonic and thermosonic bonding process.

Details

Circuit World, vol. 20 no. 2
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 February 1992

R. Kužel, J. Schejbal and M. Matějka

Direct copper bonded (DCB) alumina substrates are among sophisticated technical materials suitable for application in electronics, automotive and engineering industries. DCB…

Abstract

Direct copper bonded (DCB) alumina substrates are among sophisticated technical materials suitable for application in electronics, automotive and engineering industries. DCB substrates resist very severe operational conditions and assure high reliability. This technology provides alumina substrates which are very strongly bonded to copper foil, due to the solidified eutectic alloy Cu2O‐Al2O3 or a suitable vitreous solder. Such substrates are ideal for the construction of elements in microelectronics hybrid circuits, power circuits and devices. As the bonding layer of a solidified eutectic or vitreous solder is very thin, the thermal resistivity stays sufficiently low; in addition, the dilatation properties of DCB substrates are close to those of silicon. This enables soldering of large silicon chips without the risk of creating mechanical stress and allows for the production of devices with very high construction effectivity. Examples of such applications are potential‐free modules, bridge circuits, automotive ignition modules and Peltier elements. The vitreous bonding layers are advantageous for certain applications. State‐of‐the‐art DCB bonding technology was developed for DCB aluminium nitride substrates, which have even better thermal qualities.

Details

Microelectronics International, vol. 9 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 6 September 2019

Shri Kumaran Nadaraja and Boon Kar Yap

Lead frame tape is a crucial support for lead frames in the IC assembly process. The tape residue on the quad flat non-leaded (QFN) could result in low reliability and failure in…

Abstract

Purpose

Lead frame tape is a crucial support for lead frames in the IC assembly process. The tape residue on the quad flat non-leaded (QFN) could result in low reliability and failure in electrical conductivity tests. The tape residue would affect overall performance of the chips and contribute to low pass yield. The purpose of this paper is to present an in-depth study of tape residue and factors that may affect it.

Design/methodology/approach

An experiment using lead frame and tapes from three manufacturers with two types of die bond adhesives, namely, die attach film (DAF) and wafer back coating (WBC), was conducted. Copper (Cu) wire bonding and die bonding performances were measured in terms of process capability, stitch bond strength and die attach strength.

Findings

Results showed that no tape residue was observed on the thermoplastic adhesive-based lead frames manufactured by Hitachi after the de-taping process because of the tape’s thermoplastic adhesive properties.

Originality/value

This paper studies the occurrence of tape residue and a viable solution for it through the correct process optimization and combination of semiconductor manufacturing materials. Factors that may affect tape residue have also been studied and further research can be done to explore other options in the future as an alternate solution.

Details

Microelectronics International, vol. 36 no. 4
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 January 1986

Vitramon now offers its complete range of multilayer chips with Nickel Barrier terminations to meet the needs of automatic soldering operations at high temperatures. The company's…

Abstract

Vitramon now offers its complete range of multilayer chips with Nickel Barrier terminations to meet the needs of automatic soldering operations at high temperatures. The company's unique Nickel Barrier process was developed by the central research department in Connecticut. The specially formulated materials used are designed to overcome problems that can occur at soldering due to thermal mismatch.

Details

Microelectronics International, vol. 3 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 January 1987

New Conductor Composition Reduces Firing Time by Half Du Pont has introduced a new palladium‐silver conductor composition which, with a firing cycle of only 15–30 minutes, instead…

Abstract

New Conductor Composition Reduces Firing Time by Half Du Pont has introduced a new palladium‐silver conductor composition which, with a firing cycle of only 15–30 minutes, instead of the usual 60 minutes, meets the requirements of hybrid circuit manufacturers for a material with fast‐processing characteristics.

Details

Microelectronics International, vol. 4 no. 1
Type: Research Article
ISSN: 1356-5362

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