Microcircuits polymers

Raman spectrometry is another variant which has become important. To quote one expert (Purcell 1993), In 1928, the Indian physicist C.V. Raman (later the first Indian Nobel prizewinner) reported the discovery of frequency-shifted lines in the scattered light of transparent substances. The shifted lines, Raman announced, were independent of the exciting radiation and characteristic of the sample itself. It appears that Raman was motivated by a passion to understand the deep blue colour of the Mediterranean. The many uses of this technique include examination of polymers and of silicon for microcircuits (using an exciting wavelength to which silicon is transparent). 

ABSTRACT A new class of photosensitive, thermally stable polymers containing photo-labile aromatic amide linkages has been prepared. These polymers can be used to provide lithographic relief images for printing, etch masks for microcircuit fabrication and as contrast media for optical information storage. 

Initial synthesis of GMC for process development and optimization studies was accomplished on a small laboratory scale with synthetic runs typically yielding 5-15 g of polymer. However, in order to test GMC on a production basis and introduce it into manufacture, scale-up of the synthesis was necessary. The control of molecular properties and composition had to be considerably better than for most commercial polymers. To this end, a pilot plant for the manufacture of GMC was designed, constructed, and used to produce kilogram quantities of polymer. The scale-up of GMC provides an excellent example of how basic chemical engineering principles are employed in microcircuit fabrication, as well as some of the challenges in synthesis, process control, and purification. The major components of the pilot plant are shown in Fig. 6. 

Nguyen MN, Chien lY. An Ultra Low Moisture Polymer Adhesive for BGA Packages. Inti. J. Microcircuits and Electronic Packaging. 1998 21(2). 

Polymer adhesives have found their place in numerous electronics applications. Major uses include eommercial/consumer products computers and military, space, automotive, medical, and wireless communications. Some adhesives may be used aeross several applications while others have been formulated to meet applieation-specific requirements. For example, reworkability is not a consideration for high-production, low-cost consumer products such as cell phones or calculators, but is important for high-value, high-density printed-wiring boards (PWBs) used in military and spaee electronics. Further, thermal stability at high temperatures is required for near-engine electronics in automobiles, aircraft, and for deep-well sensors, but not for office computers. The major applications for polymer adhesives are to attach and electrically insulate or to electrically connect components, devices, connectors, cables, and heat sinks to printed-circuit boards or to thin- or thick-film hybrid microcircuits. In addition, over the last several decades, new uses for adhesives have emerged for optoelectronic (OE) assemblies, microelectromechanical systems (MEMS), and flat-panel displays. 

The sensitivity of FTIR spectroscopy to microscopic defects is greatly increased compared to a macroscopic measurement - if the defective area is examined. As opposed to single element, wide beam spectroscopy where the spectrum from the entire sample is obtained, the polymer does not overshadow the contaminant if a spectrum from a microscopic area of the sample is obtained. The contaminant can be later identified from a library of known compounds, providing clues to process control and helping to maintain quality control. This approach has been used to identify gel inclusions in poly(ethylene) [28, 29], contaminant on the surface of a semi-conductor device [30], acrylic fiber on a microcircuit die (Fig. 4) [31], contaminants in poly(vinyl chloride) (PVC) [32] and a mold release agent on the surface of a polyurethane [ 33 ]. An additive (erucamide) in linear low density polyethylene (LLDPE) that was found to migrate to the surface [34] thereby changing the surface properties could be readily identified. Various contaminants, whether in a... 

Weigand, B. L., and Lieari, J. J., Polymer Adhesives Used in Hybrid Microcircuits, Army ECOMFinalRepoitECOM-76-13 lOF (1976)... 

Table 4 Coefficient of thermal expansion a at 25°C of the metals, oxides, ceramics, and polymers commonly used in the fabrication of microcircuits and electronic components.

Table 12.4 Coefficient of Thermal Expansion a at 25 °C of the Metals, Oxides, Ceramics, and Polymers Commonly Used in the Fabrication of Microcircuits and Electronic Components...

---