TECHNET Archives

January 2002

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Condense Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Sender:
Subject:
From:
Lou Hart <[log in to unmask]>
Date:
Tue, 8 Jan 2002 17:10:23 -0500
Organization:
Compunetix, Inc.
Reply-To:
"TechNet E-Mail Forum." <[log in to unmask]>
Parts/Attachments:
text/plain (30 lines)
TechNetters, I have a question regarding consistency of 7095 (Design and
Assembly Process Implementation for BGAs), SM-782 (the Surface Mount pad
document), and 7525 (Stencil Design Guidelines), resulting from discussion
with process engineers and techs earlier today.

We were looking at a BGA, 20x20 package, with 1.27 mm pitch.  The stencil
design guidelines (7525, Table 1 on p. 4), call for an aperture of 0.75 mm.
 That table also refers to a 0.80 mm pad.  SM-782 (section 14) says a 20x20
BGA will have 0.75 mm balls that should go onto 0.60 mm pads.  Do these
documents contradict each other regarding pad size, and is 7525 wrong with
regard to BGA stencils?

Further, the bare board does have 0.60 mm pads for the BGA.  7095, in
6.2.1, p. 33, says "land diameter is usually smaller than the ball
diameter..land size reduction of 20 to 25% has been determined to provide
reliable attachment...".

As always, thanks for any comments.  Lou Hart

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To recieve ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2