[SI-LIST] Re: Cross-hatched reference planes

  • From: Richard P EVANS <rich.evans@xxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Tue, 3 Apr 2007 16:48:46 -0500

 There is at least one Japanese supplier of high-density
build-up BGA substrates that requires venting of the planes.
And layer-to-layer adhesion is often a concern on BGA substrates.
So,PCB's, no, but BGA's, yes.  The stresses in a BGA can be
quite high.


Rich



-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Lee Ritchey
Sent: Tuesday, April 03, 2007 4:10 PM
To: Jeff Seeger; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Cross-hatched reference planes

All of those reasons, except the flex circuit one, went by the wayside many
years ago.  Wonder why they still linger around the industry like old socks!

Lee Ritchey


> [Original Message]
> From: Jeff Seeger <jseeger@xxxxxxxxxxxxxx>
> To: <leeritchey@xxxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> Date: 4/3/2007 1:48:55 PM
> Subject: Re: [SI-LIST] Re: Cross-hatched reference planes
>
> Lee Ritchey wrote:
>
> >Jeff,
> >
> > What are the situations where these items apply?  We'd like to know 
> > as
we
> >hear such statements often without any accompanying explanations.
> >
> >
>  > snip <
>
> >>
> >>Lee Ritchey wrote:
> >> >
> >> >  Unless this is a flex circuit, why would you cross hatch a plane?
> >>
> >>    Copper balance, venting, and laminate/laminate bonding
> >>    can be issues in certain situations.
> >>
>
>     While I'll confess I'm pressed for time here's a 20 sec follow up;
>     the second two are admittedly very narrow needs:
>
>     - crosshatch may be helpful to balance copper usage in a stackup to
>     minimize propensity for warpage, or on the 'outer layers" of a sub-
>     assembly in a sequential lamination construction
>
>     - venting these days is primarily of concern in device substrate
>     ie build-up multilayer
>
>     - laminate to laminate bonding can be an issue in some high stress
>     or multi-material situations
>
>     Hope that helps,
> --
>
>  
>       Jeff Seeger                         Applied CAD Knowledge Inc
>       Chief Technical Officer                  Tyngsboro, MA  01879
>       jseeger "at" appliedcad "dot" com                978 649 9800


------------------------------------------------------------------
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 technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                //www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  


------------------------------------------------------------------
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 technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                //www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: