1996 Electronics Industry Environmental Roadmap - Civil and ...

Emerging Technologies
BGA packages eliminate the use of a lead frame, but introduce a small circuit board coupon to
create fanout from the chip bond pads to the external package connections. The chip is bonded
to the circuit board coupon and the chip/circuit board combination is then typically molded inside
of a encapsulant similar to those used in more conventional plastic packages as described above.
BGAs therefore will increase the use of circuit board materials and the associated environmental
impact associated with their manufacture as described in the later discussion of printed wiring
boards.
Environmental Impacts: In each of these cases, environmental issues that require attention
concern the constituent materials of the encapsulant, the metals used for connection and
attachment, the energy consumed in high-temperature processes (especially for hermetic
processes), and the chemicals and solvents used in the packaging process. It is worth noting that,
in terms of overall contribution to the waste stream, packaging plays a substantially smaller role
than other stages of the electronics production process. Certain substances, however, such as
butyl acetate, xylene, chlorine, various acids and sulfates, and a variety of other chemicals are
used in the process. Important concerns also surround the use of the metals that form the
“bumps” that provide a platform for connecting the device to circuit boards or other substrates.
In these cases, lead-based solders are frequently used, and are currently the subject of a
substantial research activity throughout the industry.
In many cases, emerging packaging technologies will have the effect of reducing the quantity of
materials used in the packaging process by virtue of shrinking IC package sizes, and the
increasing predominance of plastic packaging will reduce energy consumption associated with
hermetic ceramic packaging. Despite the comparatively small influence of packaging, areas of
potential environmental impact must be still be addressed. Table 6-2 illustrates some example
environmental issues resulting from the more common packaging techniques.
Process Environmental Issues/Impact
Ceramic (hermetic) package production Energy consumption and waste stream from
metallization plating
Plastic (molded) package production Chemical and solid waste from encapsulating
resin production
Laminate-based plastic packages (BGA) PWB production issues (see next section)
Lead frame and finishing Chemical waste from lead frame etching and
plating/coating metals (e.g., lead, tin, gold,
palladium, etc.)
Cleaning (used between many steps) Chemical waste stream and wastewater
General facilities Energy consumption for lighting, air
conditioning, equipment
Table 6-2. Environmental impact of some common semiconductor packaging processes.
6.2.3 Interconnect
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