A major concern for blind vias is the aspect ratio; typically, .7:1 for most
PCB fab shops that can do them.  (Notice that's less than 1:1 compared to
10:1 and greater for standard TH vias.)  So, you will be using some very
thin prepreg between layers.  If you also have controlled impedance in the
50 -75 ohm range, it's a challenge.

You can download or otherwise obtain the DFM manual from most fabricators.
Select the ones you will be considering to build your boards and become
familiar with what they can/cannot do.  A good resource is the Resource
Center at Merix, http://www.merix.com/main_res.html.  You should also
discuss your needs with the fab shop's tooling and engineering department.

Best of luck!

Ray


-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Flatfield, Cadcam
Sent: Friday, June 22, 2001 2:35 AM
To: [log in to unmask]
Subject: [DC] Burried via hole

Hi,

I am looking for design specifications for blind and burried via holes.
Also am i looking for design specifications for flex and rigid flex.

Thank you,

Gerard Goossens
Flatfield multi print
Tel  :0344-622556
Fax :0344 613652

-----------------------------------
Mail  : [log in to unmask]
Website : www.flatfield.nl
-----------------------------------

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