General guide to solder balls in wave soldering—now you see them, now you don’t
create a cacophony of options, which, para- that made this possible was the standard- come to be called the ‘80% Rule’ was intro-
doxically, rather than improving the design izing of packaging I/O terminations. The duced. While it addressed the concern of
process, actually and ultimately restrict value chosen for the then-ubiquitous dual the near future, it did not look far enough
design options by forcing the designer to in-line (DIP) package so common in that ahead and as a result created a legacy that
create less-than-optimum designs caused by era was 0.100 inches (2.54 mm). Design- has created an ongoing challenge for the
the excess of options that are all in play. ers used this base number for planning electronics industry. This will be the topic
Today by some estimates, there are and executing their circuit designs, and of part two.
more than 1500 semiconductor packag- the design process was relatively simple
ing options available for the IC design with streets and avenues open for routing
engineer to choose from for his or her par- signals. Verdant Electronics founder and president
ticular unique design. This large number The change came with the introduc- Joseph (Joe) Fjelstad has more than 35 years of
is, in a way, a testament to the increase in tion of surface mount technolog,y which international experience in electronic intercon-
importance that the IC package has come was driven by two factors: One was that the nection and packaging technology in a variety
to enjoy. The truth is that the IC package dominant DIP package format proved too of capacities from chemist to process engineer
is now often the principle gating design space hungry and performance limiting to and from international consultant to CEO. Mr.
element relative to electronic system per- keep pace with the increased I/O demands Fjelstad is also a well known author writing on
formance. Unfortunately, while there have associated with ever increasing integration the subject of electronic interconnection technol-
been some improvements in design tools on the chip. The other driving factor was ogies. Prior to founding Verdant, Mr. Fjelstad
to address the problem, more typically each the rise of portable consumer electronics co-founded SiliconPipe a leader in the develop-
new IC package solution is often generated in the late 1970s and early 1980s, led by ment of high speed interconnection technologies.
in isolation, with little concern for what companies such as Sony. The combination He was also formerly with Tessera Technologies,
comes next and with little thought given to of these two events resulted in a host of a global leader in chip-scale packaging, where he
the potential benefit of co-design. new packages to replace the DIP, and Japan was appointed to the first corporate fellowship
For purposes of contrast, in the 1970s took a leading role in both their develop- for his innovations.
there were perhaps 30 different options, ment and introduction. Surface mount
and those early devices were for the most brought with it significant advantages, and
part designed to be complimentary to the there was need to provide guidance for
PCB design process. A key design element future development. As a result, what has
www.globalsmt.net Global SMT & Packaging – February 2009 – 5
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