Temperature control with a thermoelectric cooler (TEC) during laser decapsulation of plastic packages
Ablation was carried out on high voltage Schottky rectifiers at 25°C and −5°C (with a thermoelectric cooler or TEC), at 1.0 W and 3.9 W of laser power. In-situ measurement of the reverse current was conducted and correlated to the device junction temperature. It was found that the usage of a TEC increases the number of laser scans to reach the set current compliance of 100 µA after exposing the die, for ablation at 3.9 W, although eventual damage to the device is still unavoidable. The incorporation of a TEC below the sample is also demonstrated to be effective in reducing the device junction temperature during laser ablation.
Determination of temperature change inside IC packages during laser ablation of molding compound
Abstract In addition to chemical jet etch method, decapsulation performances of electronic packages for failure analysis are virtually enhanced using lasers. Nevertheless circuits inside package could be subjected to a local thermal elevation during the package ablation process. In this paper, we introduce an innovative technique to measure the thermal behavior of an encapsulated system in situ and in real time during laser decapsulation. Measurements of the heat elevation during ablation process in the three regions of interest for failure analysis are discussed: over IC, bonding and lead-frame.
Geomagnetic Polarity Epochs: Sierra Nevada Data, 3
Available paleomagnetic and radiometric results for about 60 igneous rocks 3.6 m.y. old or less are consistent with the following geomagnetic polarity epoch time scale: Brunhes normal polarity epoch, 0.0 to 0.85±0.15 million years; Matuyama reversed polarity epoch, 0.85±0.15 to 2.4±0.1 million years; Gauss normal polarity epoch, 2.4±0.1 to 3.35±0.1 million years; Gilbert reversed polarity epoch, 3.35±0.1 million years to (?). A brief interval of normal polarity (the Olduvai event) occurs within the Matuyama reversed epoch at about 1.9 m.y., and a brief interval of reversed polarity (the Mammoth event) occurs within the Gauss normal epoch at about 3.06 m.y. Data for twelve units from eastern California and Nevada, reported here for the first time, are particularly useful in defining the Gauss-Gilbert boundary and for recognizing the Mammoth event.