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

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  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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