MOTM

I believe the two inner layers are for power and ground.  Am I right, Paul?

-Richard Brewster

Adam Schabtach wrote:

>I'm currently starting to consider using SMT for my own DIY projects, and
>hence am curious about such things as a 4-layer board that uses SMT
>components finding its way into a MOTM module. I understand that the
>connectors must be through-hole, and that the remaining components can all
>be SMT (as Paul described). What I'm puzzled by is why four layers are
>necessary, and how they are utilized. I assume that vias are used to make
>transitions from one layer to another, but it still surprises me that four
>layers are necessary for a CPU, the DACs, and associated support devices. I
>imagine that it is because of the density of the board, given its small
>size.
>
>The other thing I'd like to find, and have googled for without success, is
>something which tells me what SOP, SSOP, SOIC, TQFP, etc. mean in terms of
>actual size, lead spacing, etc. I'm beginning to think I'll have to order
>one of each from Digi-Key just to have a frame of reference.
>
>--Adam
>
>  
>