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1 – 10 of over 2000
Article
Publication date: 1 August 2002

Sami Tapani Nurmi and Eero Olavi Ristolainen

This paper will describe tests of the interconnect reliability of BGA components with tin‐lead bumps soldered with leadfree solder paste during temperature cycling. Tin‐lead BGA…

Abstract

This paper will describe tests of the interconnect reliability of BGA components with tin‐lead bumps soldered with leadfree solder paste during temperature cycling. Tin‐lead BGA components soldered with tin‐lead solder paste and leadfree BGA components soldered with leadfree solder paste were used as a reference. The leadfree solder used was eutectic tin‐silver‐copper. Two kinds of surface finishes were used on the printed circuit boards (PCB), an immersion gold over electroless nickel and an organic solderability preservative. The test PCBs were temperature‐cycled for 2500 cycles in the range of −40°C to +125°C and they were continuously electrically monitored during the cycling. The results of the temperature cycling test showed that lead‐ containing BGA components soldered with leadfree solder paste don't show any serious reliability risks and can actually withstand temperature cycling stresses better than entirely leadfree BGA assemblies.

Details

Soldering & Surface Mount Technology, vol. 14 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 September 2005

Martin Goosey

To give an overview of the issues encountered, and changes that need to be made in the various types of soldering process when converting them from conventional to leadfree

Abstract

Purpose

To give an overview of the issues encountered, and changes that need to be made in the various types of soldering process when converting them from conventional to leadfree assembly.

Design/methodology/approach

This paper has been written to provide a review of the leadfree reflow, wave and hand soldering processes. Problem areas highlighted and methods for adjusting and optimising each type of soldering process for compatibility with leadfree solders are described.

Findings

The move to leadfree soldering in electronics assembly can lead to a number of issues that affect process performance, yields and reliability. Problems that are sometimes encountered with conventional lead‐bearing solders can exacerbated when moving to leadfree. Many of the issues are associated with the higher melting points of the recommended leadfree solders. Fortunately, these issues are now well known and, with care and attention to process optimisation, they can largely be avoided.

Originality/value

The value of the paper lies in its ability to provide information on the types of problems and issues encountered when moving to leadfree solders and the advice it gives on how to avoid them. It also describes how to convert the various leadfree soldering processes used in PCB assembly using a range of measures that can minimise defects, avoid common problems and optimise yields. Sources of additional assistance are also identified.

Details

Circuit World, vol. 31 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 27 June 2008

Meng‐Kuang Huang and Chiapyng Lee

The purpose of this paper is to describe the board level reliability test results of four IC packages with leadfree balls/platings, soldered with leadfree solder paste, during…

Abstract

Purpose

The purpose of this paper is to describe the board level reliability test results of four IC packages with leadfree balls/platings, soldered with leadfree solder paste, during thermal cycling. The board level reliability test results of tin‐lead balled/plated packages soldered with leadfree solder paste have also been included for comparison.

Design/methodology/approach

Four different packages, i.e. ball grid array (BGA), chip scale package (CSP), quad flat package (QFP) and thin small outline package (TSOP), were assembled on a test printed circuit board (PCB) as the test vehicle. Leadfree and tin‐lead BGA/CSP packages were equipped with Sn‐3.0Ag‐0.5Cu and Sn‐37Pb solder balls, respectively. The lead‐frames of leadfree QFP/TSOP leaded‐packages were plated with Sn‐58Bi and those of tin‐lead QFP/TSOP leaded‐packages, Sn‐37Pb. The leadfree solder paste used in this study was Sn‐3.0Ag‐0.5Cu. Two kinds of surface finishes, immersion gold over electroless nickel (Au/Ni) and organic solderability preservative, were used on the PCBs. The test PCBs were thermal cycled 5,000 times within the temperature range of −40 to 125°C and electrically monitored during the thermal cycling.

Findings

It was found that the tin‐lead balled/plated BGAs, CSPs, QFPs and TSOPs soldered with leadfree solder paste showed serious board level reliability risks as their abilities to withstand thermal cycling stresses are much weaker than those of entirely leadfree assemblies. Neither package nor surface finish was found to have any effects on the board level reliability of test vehicles with leadfree balled/plated BGAs, CSPs, QFPs and TSOPs. Metallographic examinations were conducted to investigate the effect of thermal cycling on the failure modes of solder joints.

Originality/value

The paper is of value by contributing to research in the use of leadfree solder paste with lead‐containing packages in the industry. Currently, there is a deficiency of knowledge in this area.

Details

Soldering & Surface Mount Technology, vol. 20 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 December 2001

L. Yang, J.B. Bernstein and K. Chung

This paper will review the challenges brought by leadfree soldering and some preliminary experimental evaluation results will be discussed. The initial results show that the lead

Abstract

This paper will review the challenges brought by leadfree soldering and some preliminary experimental evaluation results will be discussed. The initial results show that the leadfree soldering process with 260°C reflow peak temperature does not directly cause failures for bismaleimide‐triazine (BT)‐based fine pitch ball grid array (FPBGA) packages. However, the strict leadfree soldering condition could degrade the integrity of weak interface joints and potentially damage the package in subsequent unbiased highly accelerated stress test (unbiased HAST) evaluation. The impacts of leadfree soldering with high reflow temperature on concurrent available electronics components could be more severe than previously believed. In the future, new materials and design concepts should be applied to enhance the package reliability under strict leadfree soldering conditions.

Details

Microelectronics International, vol. 18 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 December 2003

Martin Goosey

Over the last few years, the emergence of new European draft legislation has focussed electronics industry attention on the likely ultimate proscription of lead in electronics…

Abstract

Over the last few years, the emergence of new European draft legislation has focussed electronics industry attention on the likely ultimate proscription of lead in electronics assembly. Much work has already been undertaken to identify the possible alternatives to conventional tin‐lead solders and to evaluate their performance benefits and limitations in comparison with the traditional materials. Although, some companies are already offering products manufactured using leadfree products, there is still a widespread lack of activity in many areas. With this none‐too‐distant deadline rapidly approaching, Envirowise has sponsored this paper as part of its coordinated activities to assist the UK electronics industry and to promote environmental efficiency and best practice. This paper details the current situation with respect to the drivers towards the adoption of leadfree assembly before giving an overview of the current situation. This paper concludes with details of sources of further information.

Details

Circuit World, vol. 29 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 22 June 2012

Y.S. Lin, W.J. Lin and L.Y. Chiu

The purpose of this paper is to investigate the effects of H2 flow rate on improving the solder wettability of oxidized‐copper with liquid leadfree solder (96.5Sn‐3Ag‐0.5Cu) by…

Abstract

Purpose

The purpose of this paper is to investigate the effects of H2 flow rate on improving the solder wettability of oxidized‐copper with liquid leadfree solder (96.5Sn‐3Ag‐0.5Cu) by Ar‐H2 plasmas. The aim was to improve the solder wettability of oxidized copper from 0 per cent wetting of copper oxidized in air at 260oC for 1 hour to 100 per cent wetting of oxidized‐copper modified by Ar‐H2 plasmas at certain H2 flow rates and to find correlations between the surface characteristics of copper and the solder wettability with liquid leadfree solder.

Design/methodology/approach

To reduce the copper oxides on the surfaces of oxidized‐copper for improving solder wettability with liquid leadfree solder, this study attempted to apply Ar‐H2 plasmas to ablate the copper oxides from the surfaces of oxidized‐copper by the physical bombardment of the Ar plasmas and to reduce the surfaces of oxidized‐copper by the chemical reaction of H2 plasmas with the surfaces of oxidized‐copper.

Findings

The solder wettability of oxidized‐copper was found to be highly dependent on the surface characteristics of the copper. The values of polar surface free energy and dispersive surface free energy on the surfaces of oxidized‐copper modified by Ar‐H2 plasmas were close to those values of solid leadfree solder, which resulted in improved solder wettability with liquid leadfree solder. Auger spectra indicated that the Ar‐H2 plasma modification was used to remove the copper oxides from the surfaces of oxidized‐copper.

Originality/value

The surface characterization of copper surfaces is typically determined by expensive surface analysis tool such as Auger Electron Spectroscopy (AES). This paper reports the results of a study of a promising technique called the sessile drop test method, for examining the surface free energies such as total surface free energy, polar surface free energy and dispersive surface free energy on the surfaces of copper to clarify how the solder wettability of oxidized‐copper with liquid leadfree solder was enhanced by Ar‐H2 plasmas.

Details

Soldering & Surface Mount Technology, vol. 24 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 11 April 2008

John Lau, Jerry Gleason, Valeska Schroeder, Gregory Henshall, Walter Dauksher and Bob Sullivan

The High Density Packaging Users Group Consortium has conducted a study of process development and solder‐joint reliability of high‐density packages on printed circuit boards…

Abstract

Purpose

The High Density Packaging Users Group Consortium has conducted a study of process development and solder‐joint reliability of high‐density packages on printed circuit boards (PCB) using a low‐melting temperature leadfree solder. The purpose of this paper is to investigate the reliability tests (e.g. temperature cycling and shock and vibration) and failure analysis (FA) of high‐density packages on PCB with the low‐melting temperature leadfree solder (Sn‐57 wt%Bi‐1 wt%Ag).

Design/methodology/approach

The design for reliability, materials, and assembly process aspects of the project have been discussed in “Design, materials, and assembly process of high‐density packages with a low‐temperature leadfree solder (SnBiAg)” also published in this journal issue. In this study, reliability tests (e.g. temperature cycling and shock and vibration) and FA of high‐density packages on PCB with the low‐melting temperature leadfree solder (Sn‐57 wt%Bi‐1 wt%Ag) are investigated.

Findings

Leadfree solder‐joint reliability of high‐density packages, such as the PBGA388, PBGA256, PBGA208, PBGA196, PBGA172, PQFP80, and TSSOP56 were determined by temperature cycling, shock, and vibration tests. Temperature cycling test data for over 8,100 cycles between 0 and 100°C in a 44 min. cycle were statistically analyzed. Shock and vibration test data based on the HP Standard Class Bi‐II Products SPEC have also been reported.

Originality/value

Currently there is a lack of experimental and simulation data and field experience in respect of one of the critical issues for industry – that of solder joint reliability in leadfree soldering. The paper contains some important research results and recommendations.

Details

Soldering & Surface Mount Technology, vol. 20 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 April 2003

S.T. Nurmi, J.J. Sundelin, E.O. Ristolainen and T. Lepistö

Leadfree soldering is becoming a common practice in the electronics industry because of the growing general opposition to lead‐containing solders. The reliability of leadfree

Abstract

Leadfree soldering is becoming a common practice in the electronics industry because of the growing general opposition to lead‐containing solders. The reliability of leadfree solders has been studied a lot recently, but knowledge of it is still incomplete and many issues related to them are under heavy debate. This paper presents results from a study of the formation of voids with regard to the number of reflow cycles in three different kinds of solder joints: first the ones prepared with leadfree solder paste and leadfree plastic ball grid array (PBGA) components, next the ones prepared with leadfree solder paste and tin‐lead‐silver PBGA components, and last the ones prepared with tin‐lead solder paste and tin‐lead‐silver PBGA components.

Details

Soldering & Surface Mount Technology, vol. 15 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 April 2004

Timo Liukkonen, Pekka Nummenpää and Aulis Tuominen

The electronics industry will implement leadfree soldering in the near future. Leadfree implementation steps are divided into leadfree process and leadfree product. The…

Abstract

The electronics industry will implement leadfree soldering in the near future. Leadfree implementation steps are divided into leadfree process and leadfree product. The eutectic Sn/Ag/Cu alloy seems to have become the most widely used alloy in the implementation of leadfree processes. In this study, the requirements for component placement are discussed from the leadfree process point of view. Experiments concerning the self‐alignment capability and tack strength of both tin‐lead and leadfree solder pastes are presented. According to the results, a bigger variation in self‐alignment capabilities can be expected when using a leadfree paste. The paste properties affecting the self‐alignment mechanism and tack strength are also discussed.

Details

Soldering & Surface Mount Technology, vol. 16 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 June 2005

Girish S. Wable, Quyen Chu, Purushothaman Damodaran and Krishnaswami Srihari

Historically, tin‐lead solder has been a commonly used joining material in electronics manufacturing. Environmental and health concerns, due to the leaching of lead from landfills…

Abstract

Purpose

Historically, tin‐lead solder has been a commonly used joining material in electronics manufacturing. Environmental and health concerns, due to the leaching of lead from landfills into ground water, have necessitated legislation that restricts the use of lead in electronics. The transition from tin‐lead solder to a leadfree solder composition is imminent. Several alternative solder alloys (and their fluxes) have been researched for electronics assembly in the last few years. The objective of this research was to develop a systematic selection process for choosing a “preferred” leadfree solder paste, based on its print and reflow performance.

Design/methodology/approach

After a detailed study of industry preferences, published experimental data, and recommendations of various industrial consortia, a near eutectic tin‐silver‐copper (SAC) composition was selected as the preferred alloy for evaluation. Commercially available SAC solder pastes with a no‐clean chemistry were extensively investigated in a simulated manufacturing environment. A total of nine SAC pastes from seven manufacturers were evaluated in this investigation. A eutectic Sn/Pb solder paste was used as a baseline for comparison. While selecting the best leadfree paste, it was noted that the selected paste has to perform as good as, if not better than, the current tin‐lead paste configuration used in electronics manufacturing for a particular application. The quality of the solder pastes was characterized by a series of analytical and assembly process tests consisting of, but not limited to, a printability test, a solder ball test, a slump test, and post reflow characteristics such as the tendency to form voids, self‐centring and wetting ability.

Findings

Each paste was evaluated for desirable and undesirable properties. The pastes were then scored relative to each other in each individual test. An aggregate of individual test scores determined the best paste.

Originality/value

This paper summarizes a systematic approach adopted to evaluate leadfree solder pastes for extreme reflow profiles expected to be observed in reflow soldering leadfree boards.

Details

Soldering & Surface Mount Technology, vol. 17 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

1 – 10 of over 2000