Critical Temperature to Dielectric Degradation of Printed Circuit Board
Dielectric degradation of printed circuit board based on the thermal properties in an open-air environment was investigated. With increase of the temperature, the copper electrodes were oxidized from Cu 2O to CuO; the base material of epoxy laminate was thermally affected to the change of molecular structure and degradation of dielectric properties. With increase of the temperature, the capacitance and surface resistance decreased, the thermal stimulated current increased and showed a valley value near 450 K and a peak value near 490 K
New high-density multilayer technology on PCB
We have developed a new high-density multilayer technology on PCB (Printed Circuit Board), named DSOL (Deposited Substrate On Laminate) technology. The first characteristic of the DSOL technology is the dielectric fabrication, which uses a new photosensitive material, a bulky fluorene unit bonded epoxy acrylate resin. The fluorene based resin has interesting properties such as good electrical properties, low curing temperature (160/spl deg/C) for a heat-resistant resin (glass transition temperature: 230/spl deg/C), low coefficient of thermal expansion (40 ppm), and high resolution. In particular, the dielectric formation process has the advantage that fine and high-aspect-ratio via holes are formed on FR-4 laminates through exactly the same process and manufacturing facilities as a conventional photosensitive epoxy resin. The second characteristic is the technology which patterns fine-pitch copper conductors using a semi-additive process with a sputtering method. This technology makes 40 /spl mu/m pitch lines on large-area laminates possible, as this process consists of flash wet etching of only 0.3 /spl mu/m thick sputtered thin-films. We have successfully developed a high-density packaging substrate for high-pin-count area array ASIC (Application Specific Integrated Circuit) chips (3828 pins). A high-density substrate based on the DSOL technology is the most suitable for achieving high-density packages (MCMs, CSPs, and BGAs) using fine-pitch and area array interconnection technologies.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.