Technical Library | 2019-07-19 10:21:14.0
One of the most frequently asked questions of ACI Technologies (ACI) is how to qualify and verify that the electronic systems shipped by their respective companies are Restriction of Hazardous Substances (RoHS) compliant. The RoHS directive has been implemented since July of 2006, and the preoccupation with what constitutes a compliant product continues to confuse the electronic industry. ACI receives countless inquiries regarding how to qualify and verify that the electronic systems shipped by the irrespective companies are RoHS compliant. The approach to proving compliancy requires a sequential analytical process that utilizes a decision flow chart.
Technical Library | 2019-06-20 07:45:19.0
One of the two basic risks of employing the commercially accepted, Restriction of Hazardous Substances (RoHS) compliant, lead-free (Pb-free) electronics is the threat to the electronics reliability from the growth of tin whiskers. The other basic risk deals with Pb-free solder joint reliability.
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.
Technical Library | 2017-03-15 22:35:41.0
In 2012, The European Directive on Reduction of Hazardous Substances was recast. The new version of the directive now requires products to be adequately validated as RoHS compliant in order to be eligible for CE marking and access to the EU market (...)This paper starts by reviewing the evolution of the RoHS directive and how it has evolved. It then moves on to cover the requirements and scope of the directive, as well as which standards are used to demonstrate compliance, and how those standards must be referenced in internal company quality processes.
Technical Library | 2015-07-01 16:51:43.0
Aerospace and military companies continue to exercise RoHS exemptions and to intensively research the long term attachment reliability of RoHS compliant solders. Their products require higher vibration, drop/shock performance, and combined-environment reliability than the conventional SAC305 alloy provides. The NASA-DoD Lead-Free Electronics Project confirmed that pad cratering is one of the dominant failure modes that occur in various board level reliability tests, especially under dynamic loading. One possible route to improvement of the mechanical and thermo-mechanical properties of solder joints is the use of Pb-free solders with lower process temperatures. Lower temperatures help reduce the possibility of damaging the boards and components, and also may allow for the use of lower Tg board materials which are less prone to pad cratering defects. There are several Sn-Ag-Bi and Sn-Ag-Cu-Bi alloys which melt about 10°C lower than SAC305. The bismuth in these solder compositions not only reduces the melting temperature, but also improves thermo-mechanical behavior. An additional benefit of using Bi-containing solder alloys is the possibility to reduce the propensity to whisker growth
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