Sang-Deuk Park

Field failure mechanism and improvement of EOS failure of integrated IGBT inverter modules.

In this paper, we have proved that the soft damage from human body ESD can actually cause EOS damage, while integrated IGBT inverter modules (or intelligent power modules) are operating. Failure mechanism was defined as a latchup phenomenon by ESD damage leakage. Failure modes of each failed IGBT inside two integrated IGBT inverter modules were soft and hard burnout, respectively. To determine the failure mechanism, we have done fault tree analysis. From this analysis, we could conclude the main factor as the ESD event between device ESD immunity and PCB assembly line. In addition, from the PCB assembly line, we have identified damage samples due to an ESD event. Based on this result, we have implied ESD on IGBT and intentionally caused a leakage, then applied the device to the system. After an aging test, we could reproduce soft burnout and hard burnout.

Failure analysis of video processor defined as No Fault Found (NFF): Reproduction in system level and advanced analysis technique in IC level

This paper has studied the video processors for Flat Panel Display (FPD) which is defined as No Fault Found (NFF) among field failures. NFF phenomenon of video processor was the initial feature of field failure and showed Composite Video Broadcast Signal (CVBS) noise but it worked properly after some hours. NFF phenomenon has been a rising issue in the field of electronic device and the system recently. Highly Accelerated Life Testing (HALT) method has been used to reproduce field failure symptom. Modulated exciting technique has been applied as stress profile. Through the above, it was possible to reproduce the symptom which is the same as the field failure. Fault isolation and the defect was detected through the Advanced failure analysis method such as backside polishing, PEM, OBIRCH, and SEM. And it explains the defect and suggests the stress factor which can cause the defect.

Stress Mechanism about Field Lightning Surge of High Voltage BJT Based Line Driver for ADSL System

Abstract In this paper, we have verified stress root caused by lightning surge in High voltage BJT based line driver of ADSL telecommunication and created failure mechanism. To reproduce damages in Line driver, we have applied STD surge waveform in operating condition, which is specified in IEC-6000-4-5, to component and board level. Visual isolation for Damage root was conducted with Real-time Electrical Stress Analysis (RTESA) utilizing Photon Emission Microscopy (PEM). The surge made with input of Tx output created junction breakdown of amplifier, which is made of HVBJT cells, and also caused current crowding from Vcc (supply voltage). In case of Positive pulse, current crowding was observed from between Collector and Vcc (+)12V. For negative pulse, at between Emitter and Vee (−)12V, current crowding was found. For both cases, device damage level was the same. All of these could be considered as transient latchup phenomenon created in BJT cell. Applying temporary clamping diode to line driver Tx, we have conducted Board level surge injection test. As a result, with the correlation between surge level from component level reproduction test and the one from system level, we have decided field lightning surge damage level and set up line driver protection margin.

Weak point and improvement of CMOS Schmitt Trigger Circuit used in Microcontroller about ND-mode ESD

In this study, We investigated weak point and improvement about ND-mode ESD of CMOS Schmitt trigger circuit embeded in Microcontroller. Junction spiking conditions on NMOS of the CMOS Schmitt trigger circuit were Vcc Common mode, ND-mode 1.4 kV, and 0.8-1.2 sec zap interval (pin to pin). Failure mechanism by LNPN action formed in CMOS Schmitt trigger circuit was reproduced. We have identified Root Cause and improved circuits to achieve ESD damage free.

Reliability Evaluation for an Oxygen Generator in an Air-conditioner by Accelerated Life Testing

The oxygen generators in air-conditioners separate oxygen gas from air under high pressure by PSA (Pressure Swing Adsorption) method. The equipment was newly developed and there were not enough reliability test methods for it. Since we had to bring the product into market timely, we applied accelerated life tests by which we could detect weak points and obtain life and failure rate data in a short time. Zeolite beds and compressors which are the most important items to the equipment were selected as test subject items. They were evaluated under step stress margin tests first in order to verify their operating limit in certain environmental stresses and then accelerated life tests were carried out. Additionally we had to decide the material of compressor cylinders which one material was honing and the other was graphited-coated. So two types of compressors were simultaneously tested. Stress factors for zeolite beds were temperature, humidity and oxygen density. Also, temperature, humidity and output pressure stresses were selected for compressors.

Test Automation of Embedded System Software

In this paper we present process approach regarding test automation framework and test environment set up in order to automate commercial embedded software and quantitative & qualitative analysis of automation effect.[3] Test automation process was tailored effectively prior to test automation, and the quality property of embedded software was fully understood. Test automation was applied to overcome the limitations of tedious manual testing, and to better test in the level of software integration and system integration testing.[2]