Hi Alexis,

some aspects of our experiences with the technologies you asked for are listed below.

"Alexis Meehan " wrote:

> I would like to know if there are folks out there who are regularly
> using blind/buried vias or via-in-pad technology.
> * What is your experience (sucessful or not successful)?

We have successfully applied this technology in a number of designs over the last 3 years. We
have always specified thin prepregs e.g. 1080 as outer layers for their dimensional stability
compared to RCC foil. An important issue is that the use of blind vias makes sense only in
conjunction with buried vias. A copper thickness of 20µm on the hole wall of µvias is
strongly recommended. On the wave side of the board we are even using standard 0.3mm
through-hole vias as via-in-pad on 0603 resistors and SOP packages, and have been doing this
for the last 5 years.

>
> * What is the minimum hole size you are using?

100µm for laser-drilled vias, 200µm for buried vias.

>
> * What are the cost increase or savings at the fab level and
> also the assembly/rework level?

The cost increase at the board level differs, but is in the range of 40% for a 1+6+1 board
with buried vias from layers 2 to 7, compared with a standard 8 layer board. Cost savings
result from the ability to design boards that have a high placement density on front and back
sides, thus decreasing the size of the board.

>
> I want to get real-world feedback from those who have experience with
> this. Thanks in advance for any info you can provide.
>

  Best regards

  Volkmar Huß CID

  Engineering Electronic Circuit Boards
  Aufbau- und Verbindungstechnik
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

  DRÄGER ELECTRONICS

  Draeger Electronics GmbH
  Moislinger Allee 53-55
  D-23558 Lübeck

  Tel:   +49-451-882-3998
  Fax: +49-451-882-4365
  mailto:[log in to unmask]
  Website http://www.draeger-electronics.com
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