"......It seems to me that the vast majority of
signals would not happen to align with the physical pin you needed in order to attach components side by side" - Andrew
No!!! the opposite is true. I gave the example of a complex circuit i'm now working on, showing a 16 to 4 bottom layer trace reduction by making the top SMDs present themselves as a "micro-hybrid" ie: RCL SMDs physically lumped together for just these 3 pins off my 64 pin IC. This is repeated throughout the entire circuity to varying degrees. The average "bottom layer" trace reductions looks be at least 60%.
I then force, by physical placement(ie: T,H,L,etc patterns)of the SMDs themselves to an optimized layout for the most compact and shortest routing path possibale.
This gives me great control especially for the demanding UHF transmission paths.
--- In Homebrew_PCBs@yahoogroups.com, Andrew Villeneuve <andrewmv@...> wrote:
>
> How often can this be practical? It seems to me that the vast majority of
> signals would not happen to align with the physical pin you needed in order
> to attach components side by side. You'd need to space them out and put
> small traces.
>
> I have seen some clever IC configurations along these lines, though - I've
> once seen on a production board, SMT memory ICs literally stacked atop one
> another, all the top pins soldered directly to the bottom pins, with just
> the chip-enable and write-enable signals broken out independently.
>
> -Andrew
>
> On Tue, May 25, 2010 at 10:28 AM, Richard
> <richard.liberatoscioli@...>wrote:
>
> >
> >
> > .........Yes!
> >
> > Any RCL electronically grouped is "physically grouped" into a very tight
> > formation during the "pick and place"
> >
>
>
> [Non-text portions of this message have been removed]
>