Buried Vias

[Winfield]

[ shudder ]

 

[Eeyore]

[ shudder ]

Had a recent incident with them ?

Graham

 

[MooseFET]

[ shudder ]

Do everything else first. This includes not using a FBGA part.

 

[[email protected]]

[ shudder ]

Why? They're just normal through-hole vias that have been plated over
with pre-preg...

 

[Spehro Pefhany]

On Tue, 12 Feb 2008 19:11:57 -0800 (PST), the renowned

[ shudder ]

Why? They're just normal through-hole vias that have been plated over
with pre-preg...

Each layer has to be (before lamination) drilled and through-hole
plated in several stages. Many more process steps, meaning lots more
$$$ and less yield/reliability for a given level of technology.


Best regards,
Spehro Pefhany

 

[Jamie Morken]

On Tue, 12 Feb 2008 19:11:57 -0800 (PST), the renowned

[ shudder ]

Why? They're just normal through-hole vias that have been plated over
with pre-preg...

Each layer has to be (before lamination) drilled and through-hole
plated in several stages. Many more process steps, meaning lots more
$$$ and less yield/reliability for a given level of technology.

A bit off topic but I was wondering about vias and component plated
throughholes, if a PCB is 1oz or 5oz copper plated will this
significantly decrease the hole diameter for components for the 5oz
board? If the throughholes plate at the same thickness as the traces,
I think the 5oz boards will have 0.35mm taken off the diameter of the
throughholes. (0.0014" per oz plated) Is this correct?

cheers,
Jamie

 

[[email protected]]

A bit off topic but I was wondering about vias and component plated
throughholes, if a PCB is 1oz or 5oz copper plated will this
significantly decrease the hole diameter for components for the 5oz
board?  If the throughholes plate at the same thickness as the traces,
I think the 5oz boards will have 0.35mm taken off the diameter of the
throughholes. (0.0014" per oz plated)  Is this correct?

cheers,
Jamie

Sounds correct, call the PCB shop and be sure. Some vias might end up
plated shut.

 

[John Larkin]

On Tue, 12 Feb 2008 19:11:57 -0800 (PST), the renowned

[ shudder ]
Why? They're just normal through-hole vias that have been plated over
with pre-preg...

Each layer has to be (before lamination) drilled and through-hole
plated in several stages. Many more process steps, meaning lots more
$$$ and less yield/reliability for a given level of technology.

A bit off topic but I was wondering about vias and component plated
throughholes, if a PCB is 1oz or 5oz copper plated will this
significantly decrease the hole diameter for components for the 5oz
board? If the throughholes plate at the same thickness as the traces,
I think the 5oz boards will have 0.35mm taken off the diameter of the
throughholes. (0.0014" per oz plated) Is this correct?

cheers,
Jamie

We specify finished hole sizes.

John

 

[Phil Hobbs]

On Tue, 12 Feb 2008 19:11:57 -0800 (PST), the renowned

[ shudder ]

Why? They're just normal through-hole vias that have been plated over
with pre-preg...

Each layer has to be (before lamination) drilled and through-hole
plated in several stages. Many more process steps, meaning lots more
$$$ and less yield/reliability for a given level of technology.

If you're doing fast stuff on many-layer boards, you have _got_ to get
rid of the via stubs...so it's either buried vias or back-drilling,
which causes its own set of cost and reliability headaches, as well as
taking up a lot of valuable real estate.

Cheers,

Phil Hobbs

 

[nospam]

A bit off topic but I was wondering about vias and component plated
throughholes, if a PCB is 1oz or 5oz copper plated will this
significantly decrease the hole diameter for components for the 5oz
board? If the throughholes plate at the same thickness as the traces,
I think the 5oz boards will have 0.35mm taken off the diameter of the
throughholes. (0.0014" per oz plated) Is this correct?

No because you don't know how much copper was on the board and how much was
plated and the shop will drill holes bigger to achieve the specified
finished size with the plating.
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