Appeal 2006-3013
Application 10/367,849
how to calculate the minimum printed circuit board trace width. The
Web page provides tables and graphs, and identifies for a trace
thickness of 35μm, the minimum widths for different current values.
P. 1 of printout.
7. Adam’s article also discusses a design rule (standard) IPC-2221 and
MIL-STD-275. (Abstract).
8. Adam identifies that the standards are “used as a ‘design rule’ for
trace geometry (i.e. trace cross-section) for a given pair of current and
temperature rise).” Introduction, second paragraph.
9. Adam also identifies that the resistance is dimension dependent, i.e.
resistance is lower per unit length, when the trace is wider. Page 2,
formula 3.
10. While we note that the Web document (discussed in fact 6) is
undated, we nonetheless find that it establishes the level of skill in the
art at the time of Appellant’s filing of the application. Both the web
document and Adam refer to the two standards IPC-2221 and MIL-
STD-275 as providing the guidance for sizing trace width, and Adam
identifies the standards were published in 1956 (well before
Appellant’s filing date). Introduction, second paragraph.
11. From Facts 6 through 10, we find that the skilled artisan would know
to size (set the width of) conductive traces (lines or leads) on a printed
circuit board based upon current in the trace.
12. Appellant’s admitted prior art of Figure 22 teaches a display circuit
with a plurality of pixels and which makes use of data, scan and
7
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