SMDs and 4-layer PCBs

i used freelance pcb design pretty (anyone remember bishop graphics , dos protel?), i'm doing board after quite time off (maybe 20 years) using smds , 4 layers , seems rules have changed bit.

in past religiously run 1 side vertical , other side horizontal. second snuk horizontal trace vertically (or vv) few 10ths cut water off blocking future trace. @ end rip , re-route when had no more traces run rule absolute until then.

now seems different. many smds don't allow traces between pins totally block large area of pcb on 1 side. example sam3u, 144 pins of have broken out no possibility of routing between them. regardless of going have start on component side.

in other places there components on both sides bets off , have careful not box in.

now find myself running traces on whatever side gets them through , hell rules.

on plus side 4 layers. breath of fresh air not have find space large power traces. short stub off pin , via middle layer. great stuff.

anyway couple of thoughts current state of art see it.

is fair old horizontal/vertical rule no longer applies (or @ least not much)?

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rob

some people still boards way, surface-mount ones.

the usual routing strategy these days route critical tracks supplies, decoupling , clocks.then route shortest tracks, , on, until whole board routed.

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