Blind and Buried Via's stack up

[kathiresan]

Hi,

i am designing a 12 layer PCB where we need to go for blind and buried via's.

i know what they are, i need to know possibility of via stack. i have also asked the manufacturer but i need some advice if any one have done it.

Kathir

 

[senilicus]

You could have a look at ;

https://www.google.nl/search?q=blind+burried+via&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-USfficial&client=firefox-a&channel=fflb&gfe_rd=cr&ei=3fcsVKzsG86GOvOXgdAF#rls=org.mozilla:en-USfficial&channel=fflb&q=blind+via+vs+buried+via&revid=292635647



:thumbsup:

 

[marce]

Are we talking HDI construction....If so here

https://www.we-online.com/web/en/le...multilayer_aufbauten/Multilayer_Aufbauten.php

 

[kathiresan]

Are we talking HDI construction....If so here

https://www.we-online.com/web/en/le...multilayer_aufbauten/Multilayer_Aufbauten.php

Hi,

After checking the link and did some search on my own and i am little bit confused.

is Blind & Buried via and HDI Technology is different.

 

[D.A.(Tony)Stewart]

Blind vias are OK. Stacked Blind vias are not recommended.
Use larger annular rings for BB vias.
Straight thru vias are better for reliability even if blind vias have no annual ring on outside. They can be made quite small with laser holes to reduce area consumed unless operating at GHz speeds with controlled impedance with vias to outer layer acting inductive stubs.. Simulation may be required/ Specify controlled impedance, if required and must pay for CONTROLLED IMPEDANCE TESTING at board shop with readme indicating which tracks have Z=x.

 

[marce]

No HDI technology is one way (the most common) these days of doing blind and buried via's and probably the cheapest in terms of manufacturing costs.
You can use standard drilled holes for your blind and buried vias but then board manufacture becomes a real pain as does your choice of layer stackup and layer pairs fro drilling and plating....so I would recommend HDI construction as the best option for blind and buried vias...I do more and more of these designs every year as component density increases and features get smaller (0.5mm BGA's for example).

 

[D.A.(Tony)Stewart]

Yes of course HDI, aka 3/3mil track/gap some shops with tracks down to 1.25 mil, special non glass BT laminates, etc.

depends on cost/quality/capability of qualified vendors.

 

[marce]

HDI does not have to have such small tracks...

HDI for the blind and buried via build is more cost effective than having drilled blind and buried vias due to the sequential build up of the layers.
I regularly do HDI designs where I still use trace widths between 8 and 4 thou depending on the complexity and requirements of the design, some might be a standard design where they can only get 1 device in a small BGA package, some are full blown components covering all the space on both sides of the board. I have used stacked microvia's with a full HDI build down to just the two outer layers being HDI layers the inner layers being standard and just about every combination in between, with both stacked and dog bone microvia's, via in pad, via not in pad.