Search results

1 – 4 of 4
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 18 September 2009

Jianbiao Pan, Tzu‐Chien Chou, Jasbir Bath, Dennis Willie and Brian J. Toleno

The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for…

559

Abstract

Purpose

The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for Sn3.0Ag0.5Cu (SAC305) soldered joints.

Design/methodology/approach

A four‐factor factorial design with three replications is selected in the experiment. The input variables are the peak temperature, the duration of time above solder liquidus temperature (TAL), solder alloy and thermal shock. The peak temperature has three levels, 12, 22 and 32°C above solder liquidus temperatures (or 230, 240 and 250°C for SAC305 and 195, 205, and 215°C for SnPb). The TAL has two levels, 30 and 90 s. The thermally shocked test vehicles are subjected to air‐to‐air thermal shock conditioning from −40 to 125°C with 30 min dwell times (or 1 h/cycle) for 500 cycles. Samples both from the initial time zero and after thermal shock are cross‐sectioned. The IMC thickness is measured using scanning electron microscopy. Statistical analyses are conducted to compare the difference in IMC thickness growth between SAC305 solder joints and SnPb solder joints, and the difference in IMC thickness growth between after thermal shock and after thermal aging.

Findings

The IMC thickness increases with higher reflow peak temperature and longer time above liquidus. The IMC layer of SAC305 soldered joints is statistically significantly thicker than that of SnPb soldered joints when reflowed at comparable peak temperatures above liquidus and the same time above liquidus. Thermal conditioning leads to a smoother and thicker IMC layer. Thermal shock contributes to IMC growth merely through high‐temperature conditioning. The IMC thickness increases in SAC305 soldered joints after thermal shock or thermal aging are generally in agreement with prediction models such as that proposed by Hwang.

Research limitations/implications

It is still unknown which thickness of IMC layer could result in damage to the solder.

Practical implications

The IMC thickness of all samples is below 3 μm for both SnPb and SAC305 solder joints reflowed at the peak temperature ranging from 12 to 32°C above liquidus temperature and at times above liquidus ranging from 30 to 90 s. The IMC thickness is below 4 μm after subjecting to air‐to‐air thermal shock from −40 to 125°C with 30 min dwell time for 500 cycles or thermal aging at 125°C for 250 h.

Originality/value

The paper reports experimental results of IMC thickness at different thermal conditions. The application is useful for understanding the thickness growth of the IMC layer at various thermal conditions.

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Access Restricted. View access options
Article
Publication date: 1 October 2006

Jianbiao Pan, Brian J. Toleno, Tzu‐Chien Chou and Wesley J. Dee

The purpose of this work is to study the effect of the reflow peak temperature and time above liquidus on both SnPb and SnAgCu solder joint shear strength.

1082

Abstract

Purpose

The purpose of this work is to study the effect of the reflow peak temperature and time above liquidus on both SnPb and SnAgCu solder joint shear strength.

Design/methodology/approach

Nine reflow profiles for Sn3.0Ag0.5Cu and nine reflow profiles for Sn37Pb have been developed with three levels of peak temperature (230°C, 240°C, and 250°C for Sn3.0Ag0.5Cu; and 195°C, 205°C, and 215°C for Sn37Pb) and three levels of time above solder liquidus temperature (30, 60, and 90 s). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear forces for the resistors were measured after assembly. The fracture interfaces were inspected using scanning electron microscopy with energy dispersive spectroscopy in order to determine the failure mode and failure surface morphology.

Findings

The results show that the effects of the peak temperature and the time above solder liquidus temperature are not consistent between different component sizes and between Sn37Pb and Sn3.0Ag0.5Cu solder. The shear force of SnPb solder joints is higher than that of Sn3.0Ag0.5Cu solder joints because the wetting of SnPb is better than that of SnAgCu.

Research limitations/implications

This study finds that fracture occurred partially in the termination metallization and partially in the bulk solder joint. To eliminate the effect of the termination metallization, future research is recommended to conduct the same study on solder joints without component attachment.

Practical implications

The shear strength of both SnPb and SnAgCu solder joints is equal to or higher than that of the termination metallization for the components tested.

Originality/value

Fracture was observed to occur partially in the termination metallization (Ag layer) and partially in the bulk solder joint. Therefore, it is essential to inspect the fracture interfaces when comparing solder joint shear strength.

Details

Soldering & Surface Mount Technology, vol. 18 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Available. Content available
Article
Publication date: 18 September 2009

Martin Goosey

249

Abstract

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

Access Restricted. View access options
Article
Publication date: 25 February 2019

Dániel Straubinger, Attila Géczy, András Sipos, András Kiss, Dániel Gyarmati, Oliver Krammer, Dániel Rigler, David Bušek and Gábor Harsányi

This paper aims to present a novel approach on investigating critical current densities in the solder joints of chip-size surface-mounted components or device (SMD) components and…

173

Abstract

Purpose

This paper aims to present a novel approach on investigating critical current densities in the solder joints of chip-size surface-mounted components or device (SMD) components and ball grid array (BGA) lead-free solder joints with the focus of via-in-pad geometries. The investigation involves a numerical approach and a physical validation with selected geometry configurations and high current loads to reveal possible failure sources. The work is a continuation of a previous study.

Design/methodology/approach

Current density was investigated using finite element modeling on BGA joints. Dummy BGA components, 0402 and 0603 zero ohm jumper resistors, were used, both in daisy chain setups on standard FR4 printed circuit boards (PCBs). Respective physical loading experiments were set to find effects of elevated current density at hot zones of the joints. Cross-section analysis, scanning electron microscopy and shear force tests were used to analyze the joints.

Findings

The findings reveal alterations in the joints, while the current loading is not directly affecting the structure. The modeling reveals the current density map in the selected formations with increased current crowding zones. Overall, the degradation does not reach the level of electromigration (EM)-induced voiding due to the limiting factor of the FR4 substrate.

Practical implications

The heavy current load affects joint reliability, but there are limitations of EM-induced failures on PCB-based assemblies due to the thermomechanical weakness of the FR4 material.

Originality/value

The experiments investigate current density from a novel aspect on frequently used BGA surface mounted components with modeling configurations focusing on possible effects of via-in-pad structure.

Details

Circuit World, vol. 45 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

1 – 4 of 4
Per page
102050