[SI-LIST] Re: 0.8mm BGA routing
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Tayyab Jamil" <tayyab@xxxxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 24 Dec 2003 10:20:41 -0800
Tayyab,
Ther are two possible applications of this pitch part that come to mind.
The first is on tiny PCBs that are thin and the second is on multilayer
PCBs that are thick. Thin meaning less than 30 mils thick and thick being
above that.
For the thin PCBs, it is posible to drill 8 mil holes and plate them
successfully. This will allow a 3 mil trace to be routed, one between each
pin.
If you are using this part on a thick PCB, it is not possible to drill and
plate holes and at the same time maintain all of the clearances and
tolerances, even with no traces between pins. See my paper "Anatomy of A
Drilled Hole" on my web site, www.speedingedge.com.
Yes, there are people who will suggest that it is possible tor have through
holes and traces with this size package. It is not, when yields and
reliability are taken into account.
When a .8 mm pitch part is used on a thick PCB, the vias are drilled with a
laser and are blind, meaning they reach only to layer 2. Any leads that
must reach fartner, will require through holes. These through holes will
need to be "fanned" out from under the part with traces on layer 1. Then a
through hole can be drilled with proper clearances and tolerances.
Hope this helps.
Lee.
> [Original Message]
> From: Tayyab Jamil <tayyab@xxxxxxxxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Date: 12/24/2003 1:50:29 PM
> Subject: [SI-LIST] 0.8mm BGA routing
>
> Hello,
>
> I am currently working on a design where a 0.8 mm pitch BGA package is
used.
> Can any one suggest me the design configuration i.e trace width/spce and
> specially the via size and via hole, which i should follow and
manufacturers
> can handle this.
>
>
>
> Regards
>
> Tayyab Jamil Qureshi
> Sr. Design Engineer
> CARE Pvt. Ltd.
>
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