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/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
