paste?
i did some 1mm balls
they just did a precision application of flux on the lands, no paste
the balls just reflowed

Dennis Saputelli


Brad Velander wrote:
> 
> Brian,
>         as Dennis stated, your assembler should have some good opinions on
> your question. Other than that, my readings have led me to the opinion that
> your pad size should match the devices ball pad size, i.e. 0.27 in this
> case. The theory that sounds the most convincing on matching the ball pad
> size is that it will give you an even ball distortion between the device
> package and your board. Mismatched sizes will distort the ball shape and may
> apply uneven stresses through the ball.
>         Stencil size, that is also dependant on your other pad sizes and
> thus would have to tie together with your other pads because it would
> usually be stencilled in one pass. So your pad sizes and the desired volume
> of paste would dictate the stencil openings for the ball grid and other
> packages.
> 
> Sincerely,
> Brad Velander.
> 
> Lead PCB Designer
> Norsat International Inc.
> Microwave Products
> Tel   (604) 292-9089 (direct line)
> Fax  (604) 292-9010
> email: [EMAIL PROTECTED]
> http://www.norsat.com
> Norsat's Microwave Products Division has now achieved ISO 9001:2000
> certification
> 
> > -----Original Message-----
> > From: Brian Guralnick [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, September 09, 2002 10:32 AM
> > To: Protel EDA Forum
> > Subject: [PEDA] BGA Footprint question.
> >
> >
> >
> > Hi everyone,
> >
> >     I'm making a 54-BALL VFBGA (8mm x 9mm) package.  From a
> > Micron ram chip MT48V8M16LFFF.
> >
> > PDF =
> > http://download.micron.com/pdf/datasheets/dram/MobileY95W_3V_E.pdf
> >
> > In the mechanical package description, it says:
> >
> > 54x /O 0.35 solder ball diameter to post reflow condition.
> > The pre-reflow diameter is /O 0.33.
> >
> > Elsewhere, the spec says that the Solder ball pad: /O .27mm.
> >
> > This is all that we are told with regard to the pad size.
> > Does this mean that the land pattern should be 0.33mm, or 0.35mm?
> > What should the solder mask & paste stencil be cut out to?
> >
> > ____________
> > Brian Guralnick
> > [EMAIL PROTECTED]
> > Voice (514) 624-4003
> > Fax (514) 624-3631
> 
> ************************************************************************
> * Tracking #: 9B35124B2316D648A86D5987F7329EB693DE707F
> *
> ************************************************************************

-- 
___________________________________________________________________________
www.integratedcontrolsinc.com            Integrated Controls, Inc.    
   tel: 415-647-0480                        2851 21st Street          
      fax: 415-647-3003                        San Francisco, CA 94110

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Forum Guidelines Rules:
* http://www.techservinc.com/protelusers/forumrules.html
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to