Technical Library: rohs bga (Page 1 of 6)

Pad Cratering

Technical Library | 2020-05-08 18:22:31.0

A customer contacted the Helpline to perform analysis on a lead-free assembly which exhibited intermittent functionality. The lead-free assembly exhibiting intermittent functionality when pressure was applied to the ball grid array (BGA) packages. Industrial adaptation of a Restriction of Hazardous Substances (RoHS) compliant solder standard has created a new host of failure modes observed in lead-free assemblies. Pad cratering occurs when fractures propagate along the epoxy resin layer on the underside of the BGA connecting pads. While originating from process, design, and end use conditions, it is the combination of a rigid lead-free solder with inflexible printed circuit board (PCB) laminates that has advanced the prevalence of this condition. Pad cratering is simply the result of mechanical stress exceeding material limitations.

ACI Technologies, Inc.

Pad Cratering

Technical Library | 2020-05-08 18:22:31.0

A customer contacted the Helpline to perform analysis on a lead-free assembly which exhibited intermittent functionality. The lead-free assembly exhibiting intermittent functionality when pressure was applied to the ball grid array (BGA) packages. Industrial adaptation of a Restriction of Hazardous Substances (RoHS) compliant solder standard has created a new host of failure modes observed in lead-free assemblies. Pad cratering occurs when fractures propagate along the epoxy resin layer on the underside of the BGA connecting pads. While originating from process, design, and end use conditions, it is the combination of a rigid lead-free solder with inflexible printed circuit board (PCB) laminates that has advanced the prevalence of this condition. Pad cratering is simply the result of mechanical stress exceeding material limitations.

ACI Technologies, Inc.

Lead-Free BGA Rework-Transition Issues

Technical Library | 2007-08-16 13:34:31.0

While experienced inspectors may be able to determine the aesthetic differences between a lead-free PCB assembly and a tin-lead version, one cannot rely on the "experienced eye". "Less wetting out to the pad edges" (Figure A) and "graininess and lack of shininess of the solder joint" (Figure B) are typical comments about some lead-free solder joints. However, in cases where a Nitrogen atmosphere was present during the reflow of the solder joint (Figure C), there will be little visual differences between the lead free alloys and their tin-lead counterparts.

BEST Inc.

Testing Intermetallic Fragility on Enig upon Addition of Limitless Cu

Technical Library | 2014-01-23 16:49:55.0

As reliability requirements increase, especially for defense and aerospace applications, the need to characterize components used in electronic assembly also increases. OEM and EMS companies look to perform characterizations as early as possible in the process to be able to limit quality related issues and improve both assembly yields and ultimate device reliability. In terms of BGA devices, higher stress conditions, RoHS compatible materials and increased package densities tend to cause premature failures in intermetallic layers. Therefore it is necessary to have a quantitative and qualitative test methodology to address these interfaces.

Universal Instruments Corporation

Mixed Metals Impact on Reliability

Technical Library | 2013-12-19 16:57:50.0

With the adoption of RoHS and implementation of Lead Free solders a major concern is how this will impact reliability. Both commercial and military hardware are impacted by this change even though military hardware is considered exempt from the requirements of RoHS. As the supply chain has moved to the new lead free alloys both markets are being forced to understand these impacts and form risk mitigation strategies to deal with the change. This paper documents the effect of mixing Leaded and Lead Free alloys on BGA devices and how this impacts reliability. Three of the most common pitch BGA packages are included in the study to determine if the risk is the same as pitches decrease

Nextek

Thermal Shock and Drop Test Performance of Lead-free Assemblies with No-Underfill and Corner-Underfill

Technical Library | 2014-01-02 15:56:55.0

With ROHS compliance the transition to lead-free is inevitable. Several lead-free alloys are available in the market and its reliability has been the main concern. The results from this experimental research aims at making a comparison of different lead-free alloy combinations. Thermal shock and drop tests are a part of this experimental study.

Jet Propulsion Laboratory

The Effect of Pb Mixing Levels on Solder Joint Reliability and Failure Mode of Backward Compatible, High Density Ball Grid Array Assemblies

Technical Library | 2015-01-08 17:26:59.0

Regardless of the accelerating trend for design and conversion to Pb-free manufacturing, many high reliability electronic equipment producers continue to manufacture and support tin-lead (SnPb) electronic products. Certain high reliability electronic products from the telecommunication, military, and medical sectors manufacture using SnPb solder assembly and remain in compliance with the RoHS Directive (restriction on certain hazardous substances) by invoking the European Union Pb-in-solder exemption. Sustaining SnPb manufacturing has become more challenging because the global component supply chain is converting rapidly to Pb-free offerings and has a decreasing motivation to continue producing SnPb product for the low-volume, high reliability end users. Availability of critical, larger SnPb BGA components is a growing concern

Sanmina-SCI

The Impact of Reflowing A Pb-free Solder Alloy Using A Tin/Lead Solder Alloy Reflow Profile On Solder Joint Integrity.

Technical Library | 2008-04-29 15:50:45.0

The electronics industry is undergoing a materials evolution due to the pending Restriction of Hazardous Substances (RoHS) European Directive. Printed wiring board laminate suppliers, component fabricators, and printed wiring assembly operations are engaged in a multitude of investigations to determine what leadfree (Pbfree) material choices best fit their needs. The size and complexity of Pbfree implementation insures a transition period in which Pbfree and tin/lead solder finishes will be present on printed wiring assemblies

Rockwell Collins

Solder Joint Reliability of Pb-free Sn-Ag-Cu Ball Grid Array (BGA) Components in Sn-Pb Assembly Process

Technical Library | 2020-10-27 02:07:31.0

For companies that choose to take the Pb-free exemption under the European Union's RoHS Directive and continue to manufacture tin-lead (Sn-Pb) electronic products, there is a growing concern about the lack of Sn-Pb ball grid array (BGA) components. Many companies are compelled to use the Pb-free Sn-Ag-Cu (SAC) BGA components in a Sn-Pb process, for which the assembly process and solder joint reliability have not yet been fully characterized. A careful experimental investigation was undertaken to evaluate the reliability of solder joints of SAC BGA components formed using Sn-Pb solder paste. This evaluation specifically looked at the impact of package size, solder ball volume, printed circuit board (PCB) surface finish, time above liquidus and peak temperature on reliability. Four different BGA package sizes (ranging from 8 to 45 mm2) were selected with ball-to-ball pitch size ranging from 0.5mm to 1.27mm. Two different PCB finishes were used: electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) on copper. Four different profiles were developed with the maximum peak temperatures of 210oC and 215oC and time above liquidus ranging from 60 to 120 seconds using Sn-Pb paste. One profile was generated for a lead-free control. A total of 60 boards were assembled. Some of the boards were subjected to an as assembled analysis while others were subjected to an accelerated thermal cycling (ATC) test in the temperature range of -40oC to 125oC for a maximum of 3500 cycles in accordance with IPC 9701A standard. Weibull plots were created and failure analysis performed. Analysis of as-assembled solder joints revealed that for a time above liquidus of 120 seconds and below, the degree of mixing between the BGA SAC ball alloy and the Sn-Pb solder paste was less than 100 percent for packages with a ball pitch of 0.8mm or greater. Depending on package size, the peak reflow temperature was observed to have a significant impact on the solder joint microstructural homogeneity. The influence of reflow process parameters on solder joint reliability was clearly manifested in the Weibull plots. This paper provides a discussion of the impact of various profiles' characteristics on the extent of mixing between SAC and Sn-Pb solder alloys and the associated thermal cyclic fatigue performance.

Sanmina-SCI

Aiming for High First-pass Yields in a Lead-free Environment

Technical Library | 2010-03-04 18:11:53.0

While the electronics manufacturing industry has been occupied with the challenge of RoHS compliance and with it, Pb-free soldering, established trends of increasing functionality and miniaturization have continued. The increasing use of ultra-fine pitch and area-array devices presents challenges in both printing and flux technology. With the decrease in both the size and the pitch of said components, new problems may arise, such as head-in-pillow and graping defects

Indium Corporation

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