--- Steve Allen <[EMAIL PROTECTED]> wrote: > Hi, > I'm using Protel 99SE and I'm preparing for an upcoming layout that > promises to be a bit tight. It includes BGA's with 0.8 - 1.0mm > pitches. I'd appreciate comments/suggestions relating to > manufacturability > and design. > > Here's what I'm planning: > Manual route. I haven't heard many positive comments regarding > 99SE's auto router.
Start thinking about learning how to use an autorouter for digital wiring (even if not on this board). When used smartly, it'll save *lots* of time & cut down your crosstalk (humans design in crosstalk - we cant help it - "it looks neat"). Download the Electra Router trial or similar & play in your lunchhours > BGA and fine pitch parts will be fanned out with a via for each pad. > Minimum trace width/clearance = 0.005/0.005" (0.010" inner layers). I'd put fine layers on inside pairs first before outside. Inside layers are manufactured first & errors can be found there before adding all the other layers. All other things being equal I'd go fine line before adding layers i.e. 6 layers of 5/5 before 8 layers of 6/6, depending on how your mfr prices them (which somewhat reflects scrap rates). > Minimum annular ring = 0.005" (That is 20/10 vias). Only if your mfr is happy with this. I'd use 23/10 but then i'm in Oz. > Minimum hole size = 0.010" > Layers = 6 or 8 > LPI Solder Mask > .062" Board Thickness > 1oz copper > HASL/SMOBC Is HASL appropriate for other Fine pitch parts? I tend to think of something flatter if going below 25thou pitch. > FR4 > > Here are some questions: > What situations force the use of blind &/or buried vias? Only if you find that you really cannot route out the board. I hesitate to suggest a way of calculating this, you'll have to do it by "feel" (too many variables). I've done 12 layer boards without HDI because it was cheaper than with... > How do I design BGA land patterns? I don't have manufacturer > recommended land patterns. I've been using the on-line IPC calculator for leaded > parts, but it doesn't appear to have BGA capability. Get a suggested BGA footprint from the Protel libraries online. Their BGA ones are much better than leaded parts (IMHO)! If they don't have any in the 99SE libs, then see if they are in the P04 libs. If so, get someone to save the footprint in 99 format for you. (or use the 30day P04 demo to do this). That will cost you two cents :-) ===== Dom Bragge CID Snr PCB Designer Sydney, Australia Find local movie times and trailers on Yahoo! Movies. http://au.movies.yahoo.com ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[EMAIL PROTECTED] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[EMAIL PROTECTED] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[EMAIL PROTECTED]
