Hi Gert,
I usually refer to this design guideline poster -
http://www.we-online.com/web/en/index.php/show/media/04_leiterplatte/2012_2/dg_poster_1/141029_DesignRules_HDI_Poster_A2.pdf
According to that chart (top left) - a microvia for impedance controlled
layers require a dielectric thickness of 85-110um. This is quite thin!
Regards,
Carson
On Mon, Nov 7, 2016 at 7:59 PM, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>
wrote:
Hi Carson,
I'd like to come back to your initial question.
HDI doesn't require special Prepreg Thickness, thus you can plan your
Signal related stack-up simply based on impedance requirements. For 99% of
the High speed part of the Designs, there is no benefit in using HDI. The
major Benefit is that it saves some Layers on dense electronic Boards and
that can save money, or leave more room in the Stack up for signal Layers
with impedance control.
As a example, a regular board with 20 Layer can have 4 impedance
controlled layer 2 Power Layer and 8 general Purpose Layer all on 2mm PCB
Thickness. Using HDI might reduce the general Purpose Layers to 4, giving
you two extra impedance Controlled Layer without changing the PCB Thickness
at all.
BR
Gert
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Carson Au
Sent: Thursday, November 03, 2016 1:07 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] HDI and SERDES Channels
Hi Experts,
From my understanding, HDI build-up layers require thin prepreg layers,
leading to very thin trace widths for 100ohm differential impedance control
- and your high speed serial links would suffer great conductor loss.
How do you mitigate against this?
If your design has many build-up layers with thin build-up layers on
either side of your stripline, then it is impossible to even get something
like 100um (4mil) trace widths for your 100 ohm differential pairs!!
Regards,
Carson
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
----------------------------------------
HARTING AG & Co. KG | Postfach 11 33, 32325 Espelkamp | MarienwerderstraÃe
3, 32339 Espelkamp | www.HARTING.com
Generalbevollmächtigte Gesellschafterin: Dipl.-Hdl. Margrit Harting
Persönlich haftende Gesellschafter:
HARTING WiMa AG (Luxemburg) & Co. KG | Amtsgericht Bad Oeynhausen | HRA
8259 | Espelkamp, persönlich haftende Gesellschafterin: HARTING Führungs AG
(Registre de Commerce et des Sociétés Luxembourg) | B 170749 | Luxemburg
Vorstand: Dipl.-Kfm. Philip F. W. Harting (Vorsitzender), Dipl.-Kffr.
Maresa W. M. Harting-Hertz, Dipl.-Kfm. Dr.-Ing. E. h. Dietmar Harting, Dr.
rer. nat. Frank Brode, Dipl.-Ing. (FH), Dipl.-Wirtsch.-Ing. (FH) Andreas
Conrad, Dr. iur. Michael Pütz;
Sitz der Gesellschaft: Espelkamp | Amtsgericht Bad Oeynhausen | HRA 9021 |
UST-ld Nr. DE812136745
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
