Integrated Switches and Signal Diodes

Gideon Analytical Laboratories received several components for failure analysis: two Fairchild FDC6324L integrated load switches and two Fairchild BAV99 small signal diodes. Integrated load switches are designed for power management to minimize power loss by reducing current leakages; the FDC6324L is ideal for compact computer peripheral switching applications where 3V to 20V input and 0.6A output current capability are needed. Small signal diodes are small non-linear semiconductors that are often used in electronics where high frequencies or small currents are involved.

Gideon Analytical Laboratories performed failure analysis on the two small signal diodes. One of the BAV99s showed significant destruction to the epoxy encapsulation near pin 2, which is usually indicative of EOS (electrical overstress). After curve trace testing, the BAV99 was stripped in acid to reveal the diode and possible failure mechanism. The destruction was massive and caused the epoxy to carbonize and fuse the silica; it was impossible to view the die. This typically occurs when the die becomes hot (because of current) and destroys the epoxy polymer.

Failure analysis was also conducted on the FDC6324L integrated load switches. One had massive destruction that overwhelmed the epoxy encapsulation. It was also cracked in several locations. It had a bilateral crack directly under the spot where most of the heat occurred. This type of crack is typical when the heat generated on top of the die cannot dissipate fast enough through the silica. Thermal stress cracks occur to relieve this internal stress. The other FDC6324L had destruction around pin 4 consisting of melted metal, lifted junctions, and several cracks.

There was an important conclusion reached. All of these devices appear to be voltage failures beyond the ratings of the respective devices; the failure involved circuitry of the die. This was the cause of the heat stress, which happened very fast.

With failure analysis provided byGideon Analytical Laboratories, companies in the electronics industry can rest assured that their products are reliable. By determining the cause of failing devices, Gideon Analytical Laboratories can help companies save time, money, and public image. Whether it is in the design, manufacture, or application phase, Gideon Analytical Laboratories is here to help.