Technical Library: backward (Page 1 of 1)

The Relationship between Backward Compatible Assembly and Microstructure on the Thermal Fatigue Reliability of an Extremely Large Ball Grid Array

Technical Library | 2012-06-21 23:06:06.0

First published in the 2012 IPC APEX EXPO technical conference proceedings. Most high reliability electronic equipment producers continue to manufacture and support tin-lead (SnPb) electronic products despite the increasing trend for design and conversion


HALT Testing of Backward Soldered BGAs on a Military Product

Technical Library | 2015-11-19 18:15:07.0

The move to lead free (Pb-free) electronics by the commercial industry has resulted in an increasing number of ball grid array components (BGAs) which are only available with Pb-free solder balls. The reliability of these devices is not well established when assembled using a standard tin-lead (SnPb) solder paste and reflow profile, known as a backward compatible process. Previous studies in processing mixed alloy solder joints have demonstrated the importance of using a reflow temperature high enough to achieve complete mixing of the SnPb solder paste with the Pb-free solder ball. Research has indicated that complete mixing can occur below the melting point of the Pb-free alloy and is dependent on a number of factors including solder ball composition, solder ball to solder paste ratio, and peak reflow times and temperatures. Increasing the lead content in the system enables full mixing of the solder joint with a reduced peak reflow temperature, however, previous research is conflicting regarding the effect that lead percentage has on solder joint reliability in this mixed alloy solder joint.

Lockheed Martin Corporation

Microstructure and Intermetallic Formation in SnAgCu BGA Components Attached With SnPb Solder Under Isothermal Aging

Technical Library | 2022-10-31 17:09:04.0

The global transition to lead-free (Pb-free) electronics has led component and equipment manufacturers to transform their tin–lead (SnPb) processes to Pb-free. At the same time, Pb-free legislation has granted exemptions for some products whose applications require high long-term reliability. However, due to a reduction in the availability of SnPb components, compatibility concerns can arise if Pb-free components have to be utilized in a SnPb assembly. This compatibility situation of attaching a Pb-free component in a SnPb assembly is generally termed "backward compatibility." This paper presents the results of microstructural analysis of mixed solder joints which are formed by attaching Pb-free solder balls (SnAgCu) of a ball-grid-array component using SnPb paste. The experiment evaluates the Pb phase coarsening in bulk solder microstructure and the study of intermetallic compounds formed at the interface between the solder and the copper pad.

CALCE Center for Advanced Life Cycle Engineering

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



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