Light Switch Contamination

Gideon Analytical Laboratories received several lighting switches that were found to remain open even while the switch was closed. A light switch is most commonly used to operate electric lights, permanently connected equipment, or electrical outlets. Portable lamps such as table lamps will have a light switch mounted on the socket, base, or in-line with the cord. Manually operated on/off switches may be substituted by remote control switches, or light dimmers that allow controlling the brightness of lamps as well as turning them on or off. After a brief abrasion, the lighting connect switch functioned normally. The metal to metal interface made electrical contact at a point rather than the surface of the entire contact area. Contamination was suspected as the cause of this failure.

Electronic failure analysis was conducted to determine the cause of failure. Both the upper and lower contact areas were examined for contamination. Examination by microscope did not reveal anything apparent; no dust, flux, or corrosion. Barely visible were colorless clear viscous droplets. They had a thick, sticky consistency between solid and liquid. SEM-EDS analysis was performed and micrographs were taken to identify this strange extraterrestrial material.

The contact area was made of silver and no oxygen was present. Therefore, any substance containing oxygen must have been associated with the contamination. There was all kind of dark spots on the silver contact that were not detected in an optical image but showed up vividly in an SEM-EDS micrograph. SEM-EDS analysis showed the presence of silica, oxygen, silver, and tin. In conclusion, the contamination was a small quantity of silicone polymer. To prevent this, changes in the materials used in manufacturing were made to these light switches.

Gideon Analytical Laboratories provides clients with private, personalized, and vital information. Imagine the peace of mind you will have when you know why something is failing and know exactly how to fix it. If it has to do with electronics and it is not working properly, call Gideon Analytical Laboratories. Make sure that your products are safe and reliable. Avoid lawsuits, lost consumers and a bad reputation.

Dark spots on the silver contact

Dark spots on the silver contact

viscous droplets

viscous droplets

Upper and lower contacts

Upper and lower contacts

Spectra included Silver, Tin, Oxygen, Silicon

Spectra included Silver, Tin, Oxygen, Silicon

SEM EDS spectra of contamination

SEM EDS spectra of contamination

micrograph of contamination on contact

micrograph of contamination on contact

SEM EDS contamination

SEM EDS contamination

SEM EDS contamination

SEM EDS contamination