Gideon received six failed STMicroelectronics STW37N60DM2AG 600V MOSFETs for failure analysis. These high voltage N-channel Power MOSFET are part of the MDmesh™ DM2 fast recovery diode series. They offer a very low recovery charge (Qrr) and time (trr) combined with low RDS(on), rendering it suitable for the most demanding high-efficiency converters and ideal for bridge topologies and ZVS phase-shift converters. These were installed on an H-bridge with assured engineering support that there was no waveform overlapping during the transition.
1 Circuit Analysis 1.1 Device Failures and Circuit Description The failing units have repeatedly experienced failures of Vishay SQD50P04-13 power MOSFETs in locations Q14 and Q27. Device-level analysis performed by Gideon has indicated that the devices in location Q14 had failed due to excessive Drain-to-Source voltage avalanche condition while the devices in location Q27 had failed from excessive Drain current. Q14 and Q27 were noted as the only failed components discovered.
Gideon was asked to perform a failure analysis on two Vishay SQD50P04-13L MOSFETs in TO-252 packages. The failed MOSFETs arrived on two PCBs.
There was no external damage to the package on either Q27 or Q14.
Since MOSFETs typically fail with all terminals shorted, it is imperative to examine the remainder of the die for evidence that may or may not be present to determine a cause for the EOS.
Gideon Analytical Laboratories received several Avago HCPL-2202 Optocouplers for failure analysis. These optocouplers have a totem pole output stages and optical receiver input stages with built-in Schmitt triggers to provide logic-compatible waveforms. They feature low input current (1.6mA to 1.8mA), Mbd typical signal rate, and guaranteed performance from -40 to 85 degrees Celsius. Some of their applications include isolation of high-speed logic systems, microprocessor system interfaces, and ground loop elimination. Our goal was to determine why the Avago HCPL-2202 Octocouplers had been failing.
Gideon Analytical Laboratories received 20 failed Cortina WJLXT971ALCA4e3 Ethernet ICs to analyze. Integrated Circuits (ICs) are a set of electronic circuits on one small flat piece (or “chip”) of semiconductor material that is normally silicon. The integration of large numbers of tiny transistors into a small chip results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components. These Cortina WJLXT971ALCA4e3 ICs were suspected to be possibly mislabeled or have some kind of manufacturing defects.
Gideon Analytical Laboratories received one TI TPS767D301 dual-output low-dropout voltage regulator with a ground to reset short The TI TPS767D301 offers a transient response, low dropout voltages, and dual outputs. It is designed primarily for DSP applications. It features extended temperature performance from 55 to 125 degrees Celsius, drop out voltage typically 350 mV at 1 A, and enhanced product-change notification. The goal was to determine why these TI TPS767D301 voltage regulators were failing, paying special attention to the ground to reset short.
Gideon Analytical Laboratories received several RY4S-UAC110-120V power relays for failure analysis. A relay is an electrically operated switch. Many relays use an electromagnet to operate the switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. Relays are used to control a high power or high voltage circuit with a low power circuit.
Gideon Analytical Laboratories received a TI TMS320F28335PGFA Digital Signal Processor for failure analysis. Digital Signal Processing applications include audio and speech processing,sonar,radar, and other sensor array processing,spectral density estimation,statistical signal processing,digital image processing, among many others. The TI TMS320F28335PGFA features high-performance static CMOS technology, a 32-bit CPU, 16 x 16 and 32 x 32 MAC operations, and Harvard bus architecture. It has up to 88 individually programmable, multiplexed GPIO pins with input filtering.
Gideon Analytical Laboratories received three different vendor 100-ohm resistors, made by Vishay, RCD, and Stackpole, respectively. The two Stackpole resistors were open. A resistoris a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. Our goal was to test the functionality the Vishay, RCD, and Stackpole resistors, and if any were failing, determine the cause of the failure.
Gideon Analytical Laboratories received several T491D475K050AT Kemet tantalum capacitors for electronic failure analysis. A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit. The Kemet T491D475K050AT has a capacitance of 4.7 uF, a voltage rating of 50 VDC, and a tolerance of 10%, measures 7.