Use of Surface Mount Technology

Cupric chloride (CuClj) ia a strong etch employed for producing circuit patterns on the board. The etchant loses its effectiveness as copper etched from the board reduces the CuClj to cuprous chloride (CuCl). The spent etchant can be regenerated, however, by oxidizing the CuCl, using direct chlorination (DHS 1987). 

Metals from spent process solutions and rinse waters can also be recovered in many of the same ways as are employed for electroplating and other surface treatment wastes. These are discussed under Recycling in Section 7.4. 

It is important to segregate waste streams containing chelating agents from those that do not, for otherwise the chelators will inhibit metals precipitation. Waste stream segregation can reduce the amount of ferric chloride and other chemicals needs to break down metal complexes, and can minimize sludge formation. 

Waste reduction methods discussed in this chapter, and appropriate references, are listed in Table 11-1. 

WASTE MANAGEMENT FOR PRINTED CIRCUIT BOARD MANUFACTURE 

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With the growing use of surface mount technology and related techniques such as chip-on-board, printed circuit board manufacturers are continually seeking new processes to enable production of boards with increased circuit densification and decreased circuit feature sizes. Consequently, line widths are now approaching those of early semiconductor devices, and this has in turn placed new demands on the resolution capabilities of the inner-layer and outer-layer photoresists used in the industry. 

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