Longevity packaging

Whenever new chemistry is introduced into the environment, there arises the question of its effect on our health. On the positive side, plastics packaging of food prevents contamination and spoilage, and prolongs its useful life and use of plastics in medicine has made major contributions to health and longevity. On the negative side, there have been several occasions where plastics chemistry has caused health problems whenever these have been identified, they have been solved successfully and quickly. 

In the Longevity process, the UHMWPE bars are warmed, placed in a carrier on a conveyor, and are exposed to electron beam radiation, with a total dose of 100 kGy. The UHMWPE does not heat above the melt transition during the crosslinking. After irradiation, the UHMWPE is heated above the melt temperature (>135°C) for stabilization of free radicals. Components are then machined from the Longevity material, enclosed in gas-permeable packaging, and sterilized by gas plasma. 

Longevity component for hip arthroplasty with packaging (Zimmer, Inc., Warsaw IN). (A) 22-mm diameter Longevity acetabular liner. (B) Packaging of Longevity. 

The Prolong process is similar to the previously described DURASUL except that an electron beam irradiation dose of 65 kGy is used for Prolong and continuous compression-molded bars are processed as with Longevity. Components are machined from processed Prolong maferial, enclosed in gas-permeable packaging, and sterilized by gas plasma (Figure 15.6). 

The high cost of LIB cells, modules, and stack packaging is the key challenge that must be overcome a battery pack replacement could cost up to 60,000. Greater competition will continue to lower LIB costs, and LIB chemistries, packaging, and quality control, coupled to better monitoring systems, promise to resolve LIB reliability and longevity... 

The situation is not that severe in smaller, tabletop or portable electronic equipment, but it still requires packaging engineers to ameliorate the hot spots and ensure longevity of operation. Since PWBs are notoriously poor heat conductors, designers must carefully evaluate the method of heat conduction through the board, using such techniques as heat vias, embedded metal slugs, and conductive planes. 

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