Don't remember who said it first. That BGA guru in NH said it best, what's his name again and where has he been lately. BGA's ain't no big deal. Your question is valid and often repeated as are the ton's of answers. I used to simply reduce the PCB pad size by 20% of the BGA pad size and over print the PCB pad size by 10% as a function of the stencil design opening, or was it the other way around. You need to get a focus on the stencils as well. Opinion still abounds here - especially when going below, say, .8 mm CSP types. You'll be there soon enough and still no real problems. Does get intersting for simple folks like my self when designing, processing, and reworking (especially reworking) when below .5 mm stuff as uBGA's. Not really trying to be funny here but some of the basic PCB pad size formulations kinda revolved around this formulae. Pay for it if you must as IPC stuff or some other guru's advice. Someone better than me has the answers as in the IPC archives and throughout industry. I will say, BGA's in general are the nicest little parts to work with on the planet. Some exceptions exist but the soldering and solder joint making processes work very well and placement and self alignment characteristics are great. And on it goes. MoonMan --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------