Yes Steve,

Those were the days. Still active for some but for constraining or tailoring
core requirements for CTE. Don't have that problem here as after taking one
of the little beasts apart, there's really nothing inside that would
override the CTE matching characteristics both on the part and the MLB.

So, life is good but for getting the gold of the part's solder termination
areas. No problem there either.

Straigtening out the MLB's radically unbalanced construction, based on
impedance requirements, has been a bit more interesting but positive as
well. I have a .5 oz. plane on the bottom of the six layer structure and one
on the 4th layer. The space between layer 1 and layer four has to be 39
mils. So, I made the dielectrics up of 2 plies of 7628, sandwiched between 2
plies of 1080, in each of the two dielectrics. Then I made the layer 4 plane
out of 2 oz. Cu foil. The other dielectrics are all 2 ply 2113. Therefore,
when fabricated in a qualified supplier's carefully managed relamination
process, under specified time, temp, and pressure, with a well managed cool
down cycle,  the boards will be flat.

Thanks and how's that for one day's work, or was it two?

Earl

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