Factors That Affect the Electrical Reliability of Solder Bonds

Electronic devices are an indispensable part of human existence today. Even the smallest and most mundane of everyday tasks are accomplished through the use of consumer electronics. A printed circuit board is considered as the base for these essential electronic products and in the process of their design and manufacturing, solder is considered to be the glue that holds the entire PCB assembly together. Therefore, it is imperative that specific parameters are established in relation to different types of soldering materials and methods, so that manufacturers can select the best one that suits their PCB assembly process. One important parameter to consider is electrical reliability. In this article, you can find brief insights into the many factors that affect the electrical reliability of solder bonds.

Factors That Affect Electrical Reliability of Solder Bonds

Temperature Cycling

A Temperature Cycle Test (TCT) is generally used to measure the reliability, behavior and quality risks in soldering materials with respect to their CTE (Coefficient of Thermal Expansion). The effect of gradual temperature changes on the solder bond is studied to determine CTE matches and to find out which solder-surface combination is most electrically reliable in terms of the thermal stresses that the bond will be subjected to.

Thermal Shock

Electrical reliability of solders is also determined with respect to its capability to withstand sudden temperature variances which it may be subjected to in harsh working requirements. Reliability issues with the solder bond might come up in the form of bodily damage, discoloration, resistance variation and the like.

Electrochemical migration

Electrochemical migration (ECM) is the migration of the solder metal towards another polarity via ionization. The dendrite deposits formed can create short circuits or reach another conductor in the PCB to form bridges. Both these occurrences can compromise the electrical reliability of the solder bond and the functioning of the electrical circuit in question.

Transient electrical stresses

The PCB and its solder bonds may also sustain electrical reliability issues and damage from high current flow. This damage is usually caused if the solder bond is delicate and unable to absorb the sudden onset of heat. Transient stresses, like those caused by lightning, electrostatic discharge and power supply changes, also need to be factored in when determining the solder’s electrical reliability.

Other stresses

The impact of different stresses on the solder joint will have a major impact on its electrical reliability. Bending, vibrations, drops and shock, fatigue, corrosion, oxidation and humidity damage are all contributing factors towards the breakdown of a solder joint.

The increased dependence of people on electronics and use of SMT devices in harsh working conditions has necessitated the need to develop solder metals and processes with increased electrical reliability. You should choose specific solder materials that possess proven capabilities of non-corrosiveness, stress and thermal damage resistance and stability in order to create high electrical reliability in PCB assembly.

About the Author:

Alpha Assembly Solutions, Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting, photovoltaics, semiconductor packaging, automotive and others. Since its founding in 1872, Alpha has been committed to developing and manufacturing the highest quality specialty materials.

Alpha Assembly Solutions Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting.