Re: gEDA-user: BGA package prototyping

[Bob Paddock <bob.paddock@xxxxxxxxx>]

On Thursday 18 October 2007 08:39:00 pm Steve Meier wrote:

> Via in pad is possible with PCB, micro-vias arn't yet. To avoid the
> wicking or chimeny effect have the back of the board coated with an
> epoxy material prior to assembly this prevents the heat from shooting up
> the via and then sucking the solder down.

Not directly related to solving that problem but this came to mind:

"The Bleeding Edge: Inventing the 'VSHDIHTLCTEHF' Microcircuit"

"Sierra Micro Electronics has just completed six months of R&D on an exciting 
new technology: a Very Small, HDI, High-Thermal, Low CTE, High-Frequency 
(VSHDIHTLCTEHF) microcircuit."

However it has been removed from pcb007's archives.  Odd.

It is still in the Google Cache if you do a search for 
"VSHDIHTLCTEHF", via Google.

"We invented ZIG ZAG microvias to enable the position of the through-holes in 
the core to be moved around from the original fixed BGA pitch on the top 
layer to increase spacing. ZIG ZAG microvias allow each layer of stacked 
microvias to move a bit sideways. Over four layers you can move a microvia 
about 5–7 mils sideways, which is enough to move the core drill position to 
create a thicker web between drill locations on the core."




-- 
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 http://www.softwaresafety.net/ http://www.designer-iii.com/
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