S.N.A.K.E.: A Dynamically Reconfigurable Artificial Sensate Skin ...

(a) Node Front (b) Node Back
Figure 3-8: Rigid node prototype
of this project are crucial. Figure 3-7 9 shows the relative cost increase for different types
of flex. There are several other factors that also increase cost, but analyzing all of them
in detail would be beyond the scope of this document; the reader is welcome to check the
provided references if further information is needed.
It is clear that multi-layer boards cost more than twice than the average double-layer flex
board and more than thrice that of single-layer boards. Yet, it is necessary to resort to
the more expensive multi-layer flex boards in order to have enough layers to route all the
electronic components required by the goals of the project. Manufacturing the final boards
is not the only costly part, though, as they must be first prototyped. A typical four-
layer rigid board of this size can be prototyped for less than 50, the same prototype on
flex usually costs between 800 and 1,200 because of the labor involved. For this reason,
prototyping of the Skin Nodes was done on regular rigid boards, and only the “final” version
was fabricated on flex. Not all of the functionality could be tested in the rigid prototypes,
but they were essential for the design, debug and first tests. These boards are shown on
Figure 3-8.
9 Courtesy of Minco: http://www.minco.com/uploadedFiles/Products/Flex_Circuits/aa24-flex_design.pdf
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