If your pad geometry does not yield at least .1mm solder mask sliver between pads, they will want gang opening, obviously if you use a gang opening it will remove the minimum solder mask sliver from consideration, so most fab shops will prefer the ganged opening, the real question is what do the assy people prefer? .5mm centers - .1mm SM sliver = .4mm - .1mm SM oversize = .3mm pad width .4mm centers - .1mm SM sliver = .3mm - .05mm SM oversize = .25mm pad width As you can see, at .5mm it is possible, at .4mm that .05mm oversize is the killer, .075 is the least I've heard that a shop will reliably do -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Oommen Mathews Sent: Monday, February 02, 2004 7:26 AM To: [log in to unmask] Subject: [DC] Regarding Solder Mask Preference Hi., For fine pitch QFP and SOP components (.5 mm or less) which type of solder mask is preferred in a fab point of view ? Gang solder mask or individual pin/pad mask ? regards, Oommen Mathews ---------------------------------------------------------- Sr. Engineer - VLSI/System Design, Wipro Technologies Global R & D, Tower-4/First Floor/Wing-A, #72, Keonics, Electronics City, Hosur Main Road, Bangalore - 560 100. India Tel:+91 (0)80 8520408 Ext:4132 Res:+91 (0)80 6659004 email: <[log in to unmask]> -----Some of the World's Greatest Feats were Accomplished by People not Smart enough to Know they were Impossible----- ---------------------------------------------------------- Confidentiality Notice The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain confidential or privileged information. If you are not the intended recipient, please notify the sender at Wipro or [log in to unmask] immediately ------------------------------------------------------------------------ --------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 847-509-9700 ext.5315 ------------------------------------------------------------------------ --------- and destroy all copies of this message and any attachments. --------------------------------------------------------------------------------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 847-509-9700 ext.5315 ---------------------------------------------------------------------------------