Spectrum Control Pi Filter

Gideon Analytical Laboratories received a single failed Spectrum Control Pi filter on which to perform failure analysis. Capacitor-input filters (also known as Pi filters) are a type of electronic filter used to remove unwanted frequencies from a signal. They are called “Pi” filters because of their resemblance to the Greek letter “Pi”. Pi filters are primarily constructed of two capacitors and an inductor and are used in situations where the ripple of a signal or the AC and DC currents within the signal are found to interfere with each other. This Pi filter had a dead short between the lead and the body.

Failure analysis was conducted. Viewing into the end seal area, molten solder, holes in the ceramic capacitor, and missing epoxy were observed. Cross-sectioning of the Spectrum Control Pi filter revealed cracks in the capacitor near the exit point of expulsion. The solder joints showed good wetting and minimal voiding. The ceramic capacitor end showed no cracks, voiding, or other flaws. The molten metal made contact the lead and body.

Gideon Analytical Laboratories came to the conclusion that the Spectrum Control Pi filter must have suffered a voltage spike or current surge greater than the dielectric breakdown strength between the two electrodes of the capacitor. This caused a meltdown and instantaneous expulsion of the metal and epoxy.

Gideon Analytical Laboratories provides analytical services to a variety of companies in the electronics industry. These analytical services are performed with state of the scientific research equipment and results are compiled by staff with a decade of experience in the failure analysis field. Gideon Analytical Laboratories provides feedback and consultation anywhere in the production process or in the application process. The analytical services provided by Gideon Analytical Laboratories can save companies millions of dollars, thousands of hours, and damaging negative publicity. Failure analysis rendered by Gideon Analytical Laboratories can be of invaluable importance when preparing for future business.

molten metal, good contact between lead and boy

molten metal, good contact between lead and boy

Blown out epoxy and seal

Blown out epoxy and seal

cross section, no damage

cross section, no damage

Molten solder and holes in ceramic cap

Molten solder and holes in ceramic cap

polished sample, no damage

polished sample, no damage