If the design is manufacturable, much concern can be abated. Above 2 GHz, or
so, gold is needed to support the skin effect requirements getting the
electrons, or holes, on down the line. Gold is the key word here so watch
out for quality issues concerning it.

With a good design, there will be no through holes in SMT pads. They will be
necked down when possible, capped or plated over when blind vias filled, and
MLB constructions will meet specified requirements in terms of material
types (DC, loss tangent, etc.). Some materials may have problems depending
on how well suppliers manage their processes. This has been discussed many
times before but watch out for warpage (especially when using dissimilar
materials such as CLTE laminated to GETEK, as an example). Look also at
board surface conditions and those conditions found in x-sections. Don't
want excessive voiding or any delamination as these conditions will ruin
your day.

Though signal integrity will have been thoroughly thought out and verified
at the design level, TDR testing will be required as well as correlating
findings to MLB constructions, materials, dielectric thicknesses, etc.

As always, limit the rework and or repair when chip devices are involved.
Also, ensure the right devices have been selected through the DFM/CE
process. Just went through a very interesting time doing failure analysis of
GaAs devices though finding the devices not the problem as much as the
circuit protection.

MoonMan

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