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From: Fred Bartoli on 24 Feb 2010 19:20
Searching for some small components I came over that one.

http://us1.st.com/stonline/products/literature/ds/15894.pdf

Page 6 :

� Micro via SSBU allowed
� Micro via SBU to be avoided

What's the difference between SSBU and SBU vias that make the SBU to avoid?

From www.acb.be/downloads/Technology%20Overview_2008_V11.pdf
page 37, I can't see anything making a difference.

So...?


--
Thanks,
Fred.
From: Spehro Pefhany on 24 Feb 2010 21:31
On Thu, 25 Feb 2010 01:20:44 +0100, the renowned Fred Bartoli
<myname_with_a_dot_inbetween(a)free.fr> wrote:

>Searching for some small components I came over that one.
>
>http://us1.st.com/stonline/products/literature/ds/15894.pdf
>
>Page 6 :
>
>� Micro via SSBU allowed
>� Micro via SBU to be avoided
>
>What's the difference between SSBU and SBU vias that make the SBU to avoid?
>
> From www.acb.be/downloads/Technology%20Overview_2008_V11.pdf
>page 37, I can't see anything making a difference.
>
>So...?

The microvias look to be about 1/3 as deep with SSBU, no?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff(a)interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Glen Walpert on 25 Feb 2010 09:44
On Wed, 24 Feb 2010 21:31:55 -0500, Spehro Pefhany wrote:

> On Thu, 25 Feb 2010 01:20:44 +0100, the renowned Fred Bartoli
> <myname_with_a_dot_inbetween(a)free.fr> wrote:
>
>>Searching for some small components I came over that one.
>>
>>http://us1.st.com/stonline/products/literature/ds/15894.pdf
>>
>>Page 6 :
>>
>>– Micro via SSBU allowed
>>– Micro via SBU to be avoided
>>
>>What's the difference between SSBU and SBU vias that make the SBU to
>>avoid?
>>
>> From www.acb.be/downloads/Technology%20Overview_2008_V11.pdf
>>page 37, I can't see anything making a difference.
>>
>>So...?
>
> The microvias look to be about 1/3 as deep with SSBU, no?

Where did you see that? As I read it, the design rules for microvia
depth are the same for SBU (Sequential Build-Up) and SSBU (Semi-
Sequential Build-Up). The SSBU consists of two or more SBUs laminated
together. In either case there is a limit of two layers of microvia per
side per build with the current recommended process; using 2 SBUs in a
SSBU allows 8 layers of uvia vice 4 with SSU and it is hard to see how
this is better except for routing density. But perhaps I am missing
something ...
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