Failure Analysis of Transistors

Transistors are a type of switch. They are used in a variety of circuits. They are integral part of all electronics. There are two main types; NPN and PNP. Most circuits tend to use NPN. There are hundreds of transistors which work at different voltages but all of them fall into these two categories.

Success Stories

Fairchild RFP40N10 power MOSFETs

Fairchild RFP40N10 power MOSFETs

Gideon Analytical Laboratories receivedthree Fairchild RFP40N10 power MOSFETs. A MOSFET is a specific type of metal oxide semiconductor field-effect transistor (MOSFET) designed to handle significant power levels.Compared to the otherpower semiconductor devices, for example, an insulated-gate bipolar transistor (IGBT) or athyristor, its main advantages are highswitchingspeed and good efficiency at low voltages. It shares with the IGBT an isolated gate that makes it easy to drive. They can be subject to low gain, sometimes to degree that the gate voltage needs to be higher than the voltage under control.
Toshiba GT40T301S IGBT Failures on PCBs

Toshiba GT40T301S IGBT Failures on PCBs

Gideon Analytical Laboratories received two Printed Circuit Boards (PCBs) with failed Insulated-gate bipolar transistors (IGBTs). The IGBTs were Toshiba GT40T301s. An insulated-gate bipolar transistor is a three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching. It switches electric power in many modern appliances: variable-frequency drives (VFDs), electric cars, trains, variable speed refrigerators, lamp ballasts, air-conditioners and even stereo systems with switching amplifiers.
IR AUIRF7648M2 Power MOSFET

IR AUIRF7648M2 Power MOSFET

Gideon Analytical Laboratories received two failed AUIRF7648M2 MOSFETs. These are rather new on the market and specifically designed for the automotive industry. Typically, when a MOSFET fails, all terminals short. It is the failure analyst’s job to discover how the MOSFET failed in the application by combining the schematics, clues found in the failure analysis, and clues found on the PCB to give a complete picture to help resolve the client’s problem.
N-channel JFET 2N4856

N-channel JFET 2N4856

Gideon Analytical Laboratories received several failed N-channel JFET 2N4856 parts. Several good N-channel JFET 2N4856 parts were also provided for comparison. A junction gate field-effect transistor (JFET) is a simple type of field-effect transistor. JFET source, respectively. The JFET 2N4856 were taken out of the application because of a waveform distortion at elevated temperature. The suggestion was to identify an electrical parameter (one or more) by which these unstable JFETs could be eliminated by a screen.
Linear Microcircuit Modular Hybrid

Linear Microcircuit Modular Hybrid

Gideon Analytical Laboratories received one linear microcircuit modular hybrid FK23009 for electronic failure analysis. A hybrid integrated circuit (HIC) is a miniaturized electronic circuit constructed of individual devices, such as semiconductors and passive components like resistors or inductors, and typically encapsulated in epoxy. The hybrid microcircuit is used in military and communications applications and is excellent for creating custom analog circuits, such as amplifiers and modulators. Thick film technology is often used as the interconnecting medium for hybrid integrated circuits.
Fairchild 740L6000 Internal Contamination

Fairchild 740L6000 Internal Contamination

Gideon Analytical Labs received four Fairchild 74OL6000 field failed Optocouplers along with three good (virgin green dot) devices in which a comparison could be done. The LSTTL input compatibility is provided by an input integrated circuit, with industry standard logic levels. This input amplifier IC switches a temperature compensated current source driving a high speed 850 nm AlGaAs LED emitter. This integration scheme eliminates CTR degradation over time and temperature. The emitter is optically coupled to an integrated photodetector/high-gain, high-speed output amplifier IC.
Siliconix Si4998DY MOSFET

Siliconix Si4998DY MOSFET

Gideon Analytical Laboratories received several dual N-channel SO-9 Vishay Siliconix MOSFETs. MOSFETs are transistors used for amplifying or switching electronic signals. The MOSFET is the most common transistor in both digital and analog circuits, used in many scenarios where voltage conversion is necessary. These dual N-channel SO-9 Vishay Siliconix Si4980DY MOSFETs were received for component evaluation and environmental testing in a variety of conditions to determine any noticeable flaws or anomalies with the package, die, or electrical parameters.
Failure Analysis of EDN337N FET

Failure Analysis of EDN337N FET

Gideon Analytical labs received one FDN337N-channel FET for failure analysis. The Drain-Source was reported shorted. Super SOTTM-3 N-Channel logic level enhancement mode power field effect transistors are produced using Fairchild’s high cell density DMOS technology. This very high-density process is specially tailored to minimize on-state resistance. These devices are particularly suited for low voltage applications in notebook computers, portable phones, PCMCIA cards, and other battery powered circuits where fast switching and low in-line power loss are needed in a very small outline surface mount package.
Photocoupler Avago HCPL 0630 Failure Analysis

Photocoupler Avago HCPL 0630 Failure Analysis

Gideon Analytical Labs received one failed photocoupler, an Avago HCPL 0630 in an 8 pin DIP SOIC -8 package. The reported failure came from the field after approximately 1.5 years of operation. The HCPL-0630 optocoupler is an optically coupled logic gate that combines a GaAsP light emitting diode and an integrated high gain photo detector. An enable input allows the detector to be strobed. The output of the detector IC is an open collector Schottky-clamped transistor.
Photocoupler Vishay IL420 Failure Analysis

Photocoupler Vishay IL420 Failure Analysis

Gideon Analytical Labs received one failed photocoupler, a Vishay IL 420, for failure analysis along with two virgins (unused) optocouplers for comparison. The basic function of a Photo Coupler is to have electronic isolation, including potential isolation (as in the case of the transformer) in an electrical circuit. Devices of the Photo Coupler family include Photo Transistor, Photo Darlington Transistor, Photo Triac and OPIC. These devices have the characteristics of excellent isolation, high CTR, compact package, high-speed operation, low decay and unit control function not being influenced by field effects.
Fairchild RFP40N10 MOSFET Failure Analysis

Fairchild RFP40N10 MOSFET Failure Analysis

Gideon Analytical Labs received three-failed Fairchild RFP40N10 power MOSFETs. All the terminals were shorted. A MOSFET is a voltage-controlled power device. If no positive voltage is applied between gate and source, the MOSFET will be non-conducting. If a positive voltage is applied to the gate an electrostatic field between it and the rest of the transistor will be produced. This positive gate voltage will push away the holes inside the p-type substrate and attracts the movable electrons in the n-type regions under the source and drain electrodes.
Optocoupler Fairchild QTC H11N1 Failure Analysis

Optocoupler Fairchild QTC H11N1 Failure Analysis

Gideon Analytical Labs received several Fairchild QTC H11N1s, a high-speed logic optocoupler, in 6-pin plastic DIPs. The devices were reported as some good, some intermittent and some not working in the application. The main function of an opto-isolator is to block high voltages and voltage transients, so that a surge in one part of the system will not disrupt or destroy another part of the circuit. Opto-couplers allow a signal to be sent in digital (some analog) between circuits.
IR FR22ON MOSFET Failure Analysis

IR FR22ON MOSFET Failure Analysis

Gideon Analytical Labs received a failed IR FR22ON MOSFET within DC-DC converter. All the MOSFETs were shorted on all terminals. The MOSFETs were tested by lifting the gate and source wires from the circuitry. The Idss leakage for a good IR MOSFET is typically around less than 1 nano-amp. All the good MOSFETs tested were around .8 nano-amps, BVdss 220V, Vgsth 3.6, Igss <100nA. This IR FR220N has thermal damage. This typically overwhelms the junctions with current (heat) and the weakest hex cells are destroyed first.
AS169 PHEMT Failure Analysis

AS169 PHEMT Failure Analysis

Gideon Analytical Labs received several failed AS169 PHEMT DC 2676 transistors on several PCBs (pseudomorphic high electron mobility transistor) is a field effect transistor incorporating a junction between two materials (GaAs and AlGaAs) with different valence and conduction bands (band gap is the difference between the two bands for the two materials) as opposed to a doped region where a MOSFET structure would be formed. The thickness of the one material is stretched such that the band gap opens more than it normally would which allows better performance because the lattice does not bunch up when the two materials are forced together.
IC BSP 77 HITFET Failure Analysis

IC BSP 77 HITFET Failure Analysis

Gideon Analytical Labs received two BSP 77 HITFET devices with resistive shorts. The HITFET is a highly integrated temperature protected FET low-side switch which provides protection from short circuits, overloads, voltage surges, open circuits, excessive temperature, and ESD. These low-side switches are versatile power transistors specially designed for automotive and industrial applications. Their built-in intelligence and protective features offer improved performance and reliability over discrete components. The die is covered with a polyimide over glassivation on top of the trace lines.
Phototransistor Failure

Phototransistor Failure

Gideon Analytical Laboratories received a failed SFH 320 optocoupler in a dual S0-8 package for failure analysis. Optocouplers can be used in many applications, including phototransistor, phototriac, or photodarlington outputs, in a range of through-hole and surface-mount package types. Many are digital optocouplers are used in the automotive industry. They come in a variety of AC and DC configurations, have high noise immunity, and are high temp devices. Two functionally good optocouplers were supplied for comparison.
Optocoupler Failures

Optocoupler Failures

Gideon Analytical Laboratories received two failed photocouplers for failure analysis. These photocouplers feature a high isolation voltage, high-speed switching, and high collector to emitter voltage. They are used in many types of applications, including power supply, telephones, and fax machines. The optocoupler was electrically tested; there was a short on both input diodes. The goal was to determine the cause of this failure. After curve trace tests were performed, both failed devices were immersed in a low surface tension dye penetrant This is a modified Mil-Std 1014.
IXYS IXGH32N60B Passivation Defect on IGBT

IXYS IXGH32N60B Passivation Defect on IGBT

Gideon Analytical Laboratories performed failure analysis on severalIXYS IGBT IXGH32N60B transistors, encased in TO-247 packages. These transistors are 60 amp 600V 2.3 Rds 200W. The concern was that the devices were not functioning as 600V but topped out at 480V in the application. Displayed in the picture above is a defect near the guard ring. Further analysis revealed there are several metal posts contacting more than likely underlying diffusion for voltage termination.