I have the August 2000 publication and the reference section is not on my document. What Rev do you have. Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Friday, March 30, 2007 12:51 PM To: [log in to unmask] Subject: Re: [TN] Solder Resist Encroachment onto BGA pads Hi Paymon! Below are a couple of *.pdf's from manufacturers that recommend NSMD lands for improved reliability: http://www.necel.com/pkg/en/mount/CHAPTER5_E.pdf http://www.altera.com/literature/an/an114.pdf Also, the IPC-7095 guideline states at 8.4.3: "...increases in fatigue life by factors of 1.25 to 3 can be anticipated with the use of non-soldermask defined (NSMD) vs. SMD lands with the larger improvements with for solder joints with the more severe loading conditions." -Steve Gregory- -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Paymon Sani Sent: Friday, March 30, 2007 12:15 PM To: [log in to unmask] Subject: Re: [TN] Solder Resist Encroachment onto BGA pads Thank you John, is there any studies on this? Paymon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke Sent: March 30, 2007 12:45 PM To: [log in to unmask] Subject: Re: [TN] Solder Resist Encroachment onto BGA pads Actually yes. If you put solder resist over the lands for the BGA you have by definition a joint defined by the resist system. Effectively this will give you a 90 degree wetting angle which is - you guessed it a stress riser. So a joint with solder mask defined joints will be more liable to crack under stress. John John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Paymon Sani Sent: Friday, March 30, 2007 9:02 AM To: [log in to unmask] Subject: [TN] Solder Resist Encroachment onto BGA pads Hello All, Does anybody know why IPC does not allow any solder resist encroachment onto the BGA copper defined lands for PCBs? ------------------------------------------------------------------------ ---- ----------- Confidentiality Notice This e-mail and any attachment(s) are intended for the individual or entity to which this email is addressed and may contain information that is confidential. 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