Flying lead Manufacturing

TABLE 66.1 Comparison of Flying-Lead Manufacturing Technologies... 

Traditional manufacturing processes used to create flying leads, such as pre-punching or pre-driUing, are not conducive to the quality levels and manufacturing yields required to achieve low cost, and alternative processes are needed, as described later. 

FIGURE 66.4 Manufacturing process for flying lead flexible circuit construction using (a) laser ablartion and (b) plasma etching or chemical etching. 

FIGURE 66.5 Comparison of opening sizes of flying-lead flexible circuit manufacturing... 

The manufacturing process for the double side TAB with fine flying leads and micro via holes is much more comphcated. Very few manufacturers are capable to produce the products with high yield. 

TAB S manufacturing capabilities are very different from traditional flexible circuits and they cover different apphcation area as shown in Fig. 66.10.TAB has been focusing single side fine traces with flying lead constructions. It has advantages for the volume productions of the small size circuitries because of special reel-to-reel manufacturing. 

The appropriate places for inspection of flying leads depend on the manufacturing process of the circuits. Fl)dng leads should be inspected just after they are generated by copper etching or by engraving of the substrate. Both AOI inspection and dimensional measurement are required. Usually, flying leads have a severe dimensional allowance for both line-width and pitches for... 

Another development is due to the interest in polychlorodibenzofurans, spurred by their occurrence as environmental contaminants. Polychloro-phenols are manufactured in large amounts (150,000 tons per annum) and find a wide range of uses. The usual method of manufacture involves the hydrolysis of chlorobenzenes, and side reactions, favored by high temperature, can lead to the production of polychlorodibenzofurans and poly-chlorodibenzo-p-dioxins. The Seveso incident is well known." Polychloro-biphenyls are also widely used industrial chemicals, particularly in heat exchange systems, and their pyrolysis leads to the formation of polychloro-dibenzofurans. Polychlorodibenzofurans have also been detected in the fly ash and flue gases of incinerators and industrial heating plants. The most toxic of the polychlorodibenzofurans are 2,3,7,8-tetra-, 1,2,3,7,8-penta-, and 2,3,4,7,8-pentachlorodibenzofuran, and an extensive literature exists on the environmental pollution and the results of human exposure to these substances. A particularly tragic example of the latter occurred in 1968 in the Fukuoka prefecture of Japan after consumption of rice oil contaminated with a commercial polychlorobiphenyl. 

Insofar as mercury and cadmium are concerned, and lead to a lesser extent, no matter how the incinerators are operated, a significant fraction of these materials will be volatilized during incineration and enter the ecosystem via the airborne path, unless recovered from the flues by fly ash precipitation and vapor condensation, methods of questionable merit for large scale MSW operations, uie remainder of the cadmium and lead will end up in the incinerator ash and in the incinerator residues, but all the mercury may be expected to be volatilized. This means that unless the reduction of the toxic materials at the source can be practiced, the incinerator residues and flues will need to be processed to remove lead and cadmium for recycling or for safe disposal in some other manner. The most effective and also the most economical way to prevent mercury from entering the environment from batteries is to phase out the use of mercury in batteries to the ftillest extent possible, an effort already instituted by the battery manufacturers, and to maintain an effective collection system for the mercury batteries still in use. 

Many of the innovations that have lead to Japanese commercial leadership are based on discoveries made in the United States, Great Britain, or Western Europe. Specifically, Sony Trinitron TV is based on technology "discovered" in the United States. Sony innovated a commercial system/product based on this. In the late 1960 s, Japanese TV manufacturers adopted solid state systems for their units United States manufacturers stated "they would never fly". 

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