[PCB_FORUM] Re: .8-MM BGA Geometry

Hello David and All Others To Follow,

I have used my share of "Forum Bandwith" (not to mention I actually have to
WORK now!).

All of you are thoughtful and generous with your knowledge.

I am at your service, all of you.

Sincerely,

Richard E Marion

-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of David Price
Sent: Wednesday, September 14, 2005 12:19 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: .8-MM BGA Geometry

The mix issue on 1 mm (two lines between) and the .8 mm (one line 
between) is the yields between via/annular, etch clearance shorts and 
width etching. Different shops have different yields depending on 
process (and thickness of board for drill ratio yield).

Choices tend to focus on the via and clearance:

19+ mil via, 4 width, 4 clear

20 mil via, 4 width, 4 clear wire-wire. 3.5 clear wire-via at tangent point

20 mil via, 3+ width, 4 clear (this is becoming increasingly 
preferred as 3-3.5 mil widths internal are good yield

.5 mm via, .1 mm width and clear

All are standard dogbone, don't require via-in-pad or microvia UNLESS 
there are other advantages to via-in-pad or microvia.

Regards,

David


At 08:29 AM 9/14/2005, you wrote:
>Hi Rich and list,
>
>I am also working on a board with a 0.8mm SRAM part.
>
>I was sent an Allegro file for a SIM board that the SRAM manufacturer
sells.
>
>It had 12 mil pads for the SRAM part and 17 mil via pads and a 10 mil
drill.
>
>However, the pcb was only four layers.
>
>Best regards,
>
>Tom Woznicki
>Flex Circuit Design Company
>http://www.flexdude.com/
>408-629-8343
>
>
>
>In a message dated 9/14/2005 8:01:12 AM Pacific Standard Time, 
>ricmar@xxxxxxxxxxx writes:
>Hello Stephen,
>
>
>
>The 20/10 Via keeps "popping up", must be a good choice.
>
>
>
>On the 16-Mil BGA Pad, what diameter Soldermask do you recommend?
>
>
>
>Thank you for sharing your experience with me.
>
>
>
>Sincerely,
>
>
>
>Richard E Marion
>
>169 Little Mill Road Unit 2
>
>Sandown NH 03873-2554
>
>HOME: 603-887-2266
>
>CELL: 603-247-1610
>
>FAX : 603-887-2936
>
>
>
>-----Original Message-----
>From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
>[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Feehan, Stephen
>Sent: Wednesday, September 14, 2005 9:55 AM
>To: 'icu-pcb-forum@xxxxxxxxxxxxx'
>Subject: [PCB_FORUM] Re: .8-MM BGA Geometry
>
>
>
>Richard,
>
>
>
>You can start with a 16 mil bga pad and a  20 mil pad / 10 mil drill 
>with a 28 mil
>
>anti pad for the via.
>
>
>
>In some designs I use the via in pin technology for all the gnd pins 
>of a 0.8mm bga.
>
>The drill of the micro via is 4 mils and is build into the pad. 
>Typically, I make sure
>
>Layer 2 is a gnd plane so all the micro vias hit directly into the plane.
>
>
>
>Call Merix Corp, they have local reps in MA/NH.
>
>
>
>Stephen
>
>Siemens Communications, Inc
>
>
>
>
>
>
>
>
>---------------------------------------------------------------------------
-----
>
>From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
>[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Richard E Marion
>Sent: Tuesday, September 13, 2005 6:27 PM
>To: icu-pcb-forum@xxxxxxxxxxxxx
>Subject: [PCB_FORUM] .8-MM BGA Geometry
>
>Dear Forum,
>
>
>
>My Client is utilizing a 0.8-MM SDRAM Package.
>
>
>
>The smallest BGA Pitch I have dealt with so far is 1.0-MM.
>
>
>
>The Fabrication/Assembly Vendors are yet to be determined.
>
>
>
>The PCB "target" construction is 0.062-Inch 14-Layer, three sets of 
>dual embedded stripline. No Blind/Buried Vias (all Thru Via).
>
>
>
>Questions:
>
>
>
>1.    Any recommendations for local (NH-MA) Fabrication/Assembly 
>Vendors capable of working with this BGA Geometry?
>
>2.    BGA SMT Pad Diameter?
>
>3.    BGA SMT Soldermask Diameter?
>
>4.    Thru Via Drill?
>
>5.    Thru Via Pad Diameter?
>
>6.    Alternatively, is Via-In-Pad an option?
>
>7.    Any chance of ATE Testing 0.8-MM Pitch?
>
>
>
>Thank You,
>
>
>
>Richard E Marion
>
>169 Little Mill Road Unit 2
>
>Sandown NH 03873-2554
>
>HOME: 603-887-2266
>
>CELL: 603-247-1610
>
>FAX : 603-887-2936
>
>
>
>
>
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David Price

davidp@xxxxxxxxxxxxxx

866.586.9352    Phone   Toll-Free
866-422.5312    Fax     Toll-Free

http://www.eAutoroute.com

B o r n  T o  R o u t e

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MakeDO and AutoTools

DFM
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Northampton, MA 01060



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