Diamond shape because when the solder wets out to the corners of the land the pattern is not simply a squashed ball, but has for distinct gray corners. I first heard this DFM guidance from Glenbrook. But, I have also heard it argued that these land patterns may produce stress points that could lead to reduced service life in of the joint. I don't have data to support the argument against the square or diamond land pattern design. They are not commonly used. I will say this, a key hole pattern, that can be produced by a non-solder mask defined land, can give a similar result. A distinct gray pattern where the solder wets down the trace leaving the pad. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Scott Decker Sent: Friday, April 21, 2006 1:40 PM To: [log in to unmask] Subject: [TN] BGA and CGA pad questions. All, I was talking with our Manufacturing engineer the other day and the people that make the SMD re-work station tools, about the pads used for both BGA's and CGA's. The vendor was saying that diamond pads, (square on a 45') were better for X-Ray inspection because you can see the pad verses the pin/ball better during the inspection of the solder joints. The X-Ray manufacturer' says the same thing, but has anyone done it this way yet? It sounds good to me, but does anyone have any practical experience with the diamond pads? How do you figure size between round to square, etc.? Is it just area calculations or flat side the same as diameter, etc.? Paste Mask sizing, Solder Mask defined, (not my thought) or just the standard oversize, etc.? These would be for high-reliability applications and from what I understand, the CGA is better in that respect. Any info would be great to hear. Thanks in advance. Scott Decker AKA: Padmasterson Broad Reach Engineering CAE Ph. 480-377-0400 Ext. 34 FAX. 480-968-4597 Tempe, AZ. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------