Rectifier Failure Analysis

A rectifier is a non-linear component that converts ac to dc. Rectifiers typically use non-linear devices such as diodes of thyristors. These devices permit the flow of current in only one direction. 3 phase ac drives typically use a 6 pulse bridge A rectifier is a non-linear component that converts ac to dc. Rectifiers typically use non-linear devices such as diodes of thyristors. These devices permit the flow of current in only one direction. 3 phase ac drives typically use a 6 pulse bridge rectifier with thyristors.

Both dc and ac drives need a rectifier. In a dc drive, the rectifier converts ac to dc for the motor. In the ac drive, the rectifier converts the ac to dc for the inverters that eventually produce the variable frequency, variable voltage ac for the motor. The rectifier takes 3 phase sinusoidal ac and chops out the positive sections for each phase to produce dc. The dc voltage has triangular shaped sections. The dc current has sine shaped portions. The dc voltage is 1.35 times the RMS ac voltage. To conserve power in and out, the dc current is 0.816 times the ac line current.

Success Stories

Failure Analysis on 1N645 Silicon Rectifier Diodes

Failure Analysis on 1N645 Silicon Rectifier Diodes

Gideon Analytical Laboratories received two 1N645 silicon rectifier diodes for failure analysis. One was bad and the other was a quality diode to be used for comparison. A rectifier is an electrical device that converts alternating current(AC), which periodically reverses direction, to direct current(DC), which flows in only one direction. Rectifiers are used inside the power supplies of virtually all electronic equipment. AC/DC power supplies may be broadly divided into linear power supplies ands witched-mode power supplies.
On Semiconductor SS16 Schottky Rectifier

On Semiconductor SS16 Schottky Rectifier

Gideon Analytical Laboratories received two On Semiconductor SS16 rectifier for failure analysis. The On Semiconductor SS16 Schottky Rectifier features glass-passivated junctions and a high-current capacity. Their applications include low voltage, high-frequency inverters, freewheeling, and polarity protection. Their storage temperature range is between -65 and 150 Degrees Celsius and the operating junction temperature is between -65 and 125 Degrees Celsius. Along with the two failed rectifiers, several good devices were also supplied for comparison.
Vishay SS26 Surface Mount Schottky Barrier Rectifiers

Vishay SS26 Surface Mount Schottky Barrier Rectifiers

Gideon Analytical Laboratories received four Vishay SS26 Surface Mount Schottky Barrier Rectifiers for possible premature conditions to failure. A Schottky barrier is a potential energy barrier for electrons formed at a metal-semiconductor junction. Schottky barriers have rectifying characteristics, suitable for use as a diode. These Vishay SS26 Surface Mount Schottky Barrier Rectifiers feature a low profile package, high surge capability, and are RoHS compliant. The diodes came from PCB P/N 170310142001 Rev A03 S/N 051208-231.
Vishay ES2D SM Rectifier

Vishay ES2D SM Rectifier

Gideon Analytical Laboratories, Inc. received on Vishay ES2D rectifier on a PCB. The initial condition and observation were that the diode had a conformal coating on a small circuit board in which when tested on a curve tracer had excessive leakage current across the junction and caused the PCB to fail in the application. Rectifiers are primarily used for conducting in one direction and blocking in the other. The Vishay ES2D is an ultra-fast rectifier, which means the reverse recovery time should be less than 100 ns.
Rectifier Assembly Rotors

Rectifier Assembly Rotors

Gideon Analytical Laboratories received several rectifier assembly rotors for failure analysis. A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The simplest kind of rectifier circuit is the half-wave rectifier. It only allows one half of an AC waveform to pass through to the load. Rectifiers are used as components of power supplies and as detectors of radio signals.
JanTXV1N821 Diode

JanTXV1N821 Diode

Gideon Analytical Laboratories received a JanTXV1N821 Zener diode for electronic failure analysis. A diode is a two-terminal electronic component with asymmetric conductance; it has low (ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the other. A semiconductor diode is the most common type of diode; it is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode but also permits it to flow in the reverse direction when the voltage is above a certain value, known as the breakdown voltage.
SCR FP25001P1 or Thyristor Failure Analysis

SCR FP25001P1 or Thyristor Failure Analysis

Gideon Analytical Labs received one SCR (silicon-controlled rectifier) module FP25001P1 for failure analysis. An SCR consists of four layers of alternating p- and n-type semiconductor materials, NPNP or PNPN structures. The three P-N junctions are labeled J1, J2 and, J3, for the three terminals. Silicon is used as the intrinsic semiconductor, to which the proper dopants are added. The junctions are either diffused or alloyed (an alloy is a mixed semiconductor or a mixed metal).
Triac or SCR ST Microelectronics BTA06 Triac Failure Analysis

Triac or SCR ST Microelectronics BTA06 Triac Failure Analysis

Gideon Analytical Labs received one failed ST Microelectronics BTA06 Triac a TO-220AB package. The device was reported to have failed post-burn-in. This Triac is suitable for general purpose AC switching according to ST Micro. They can be used as an ON/OFF function in applications such as static relays, heating regulation, induction motor starting circuits or for phase control operation in light dimmers, motor speed controllers. The specially recommended for use on inductive loads, thanks to their high commutation performances.
Triac Failures

Triac Failures

Gideon Analytical Laboratories received one failed optocoupler, along with two optocouplers for comparison. As a type of isolator favored by manufacturers, photocouplers serve as noise protectors in many electronic devices. This optocoupler has a minimum isolation voltage of 5300 Vrms, a typical input voltage of 1.16 V, and a peak output voltage of 600V. The goal was to identify the cause of the failure. The optocoupler was electrically tested. The input functioned normally with VF 1.
Shorted PX6A07 Silicon Rectifiers

Shorted PX6A07 Silicon Rectifiers

Gideon Analytical Laboratories received several shorted PX6A07 silicon rectifiers for failure analysis. Two good devices were provided for reference and comparison. A semiconductor diode is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals. It conducts in the forward direction and is blocked in the reverse direction. The good diodes were tested for conformance to the manufacturer’s specification. The good diodes performed per specification or exceeded electrical parameters listed.
Silicon Rectifier PX6A07

Silicon Rectifier PX6A07

This is a 6 amp plastic encapsulated silicon rectifier (PX6A07). Several of these high current diodes failed in the application. The arrow points to the spot of one of the failures on one device after the epoxy and copper lead frame was removed. The picture on the right is the anode. In the middle is the copper contact and the ring is actually the contact via solder to the P+ region of the die.