Thanks, Jack, for your input. (Long time, no talk to!) Designing with B/B vias is not the problem; getting a reasonable, standard cost differential from PCB fabricators is the problem. IMO, designers are reluctant to use B/B vias and some fabricators charge excessive prices for them, especially, laser drilled blind vias. Everyone continues to consider the use and fabrication of B/B vias as 'new technology'. Anything that's been around this industry for over a decade is not new. I am very frustrated with PCB fabricators for not keeping up with the industry they are a part of and support. We are starting to design with .5mm pitch, .3mm pad CSPs. This doesn't leave room on the inner pads for anything except in-pad, micro vias. This is especially true for PCBs in the 2 to 6 GHz range. I have asked several vendors for a cost factor to consider when using blind vias, getting less than satisfactory responses. I have posted my question to both the DC (640 subscribers) and TN (1242 subscribers) forums, getting the same results. It goes beyond interesting, Jack. Ray -----Original Message----- From: Olson, Jack [mailto:[log in to unmask]] Sent: Tuesday, April 03, 2001 10:45 AM To: 'DesignerCouncil E-Mail Forum.'; 'Ray Humphrey' Cc: [log in to unmask] ORG (E-mail) Subject: RE: [DC] Blind and Buried Vias I would like to contribute Ray, but I have only had to use blind/buried vias once in my life. I can tell you from a design point of view in Veribest it is effortless, you just state the range of layers for each via type, use vias wherever you want (whatever type you need) and the computer takes care of the rest (multiple drill files, fab dwg layers, etc) Its not that I am reluctant to use them, I just rarely see a need (yet). We are using 1mm BGAs on .093 thick boards with no problems with regular ol' vias But I have absolutely no idea how to evaluate the cost difference, since there is no way to get a "multiple quote" on a design that would prove anything. Can't you just ask a couple of fab vendors what to use as a rule of thumb for cost-adders? It IS interesting that absolutely no one knows this, or is willing to share anything about it, hmmm? Good Luck, (onward thru the fog) Jack -----Original Message----- From: Ray Humphrey [mailto:[log in to unmask]] Sent: Saturday, March 31, 2001 11:47 AM To: [log in to unmask] Subject: [DC] Blind and Buried Vias In a recent posting, Your Opinoin Needed - Designers Learning Symposium, I notice that blind and buried vias were included in the 'newer technologies' category. I also find that most designers are reluctant to use blind and/or buried vias, for various reasons. Blind and buried vias have been around for over a decade, they are not new. I have a great article from the March 1988 issue of PCD magazine talking about the use of blind and buried vias down to 2 mils in size! I am frustrated that PCB fabricators are failing to keep up with the industry they support and continue to charge excessive prices for such an old process. Much of today's technology require the use of blind and/or buried vias - I say it is time for designers to get over their paranoia and for fabricators to stop taking advantage of it! Several days ago, I posted this question to the DC forum, "Could someone please give me a general guideline concerning the additional cost of using blind vias on a PCB? Perhaps there is someone out there in the PCB fabrication business or a fellow designer that has done some extensive research into this?" To date, I have not received a single response. Isn't it time we stopped considering blind and buried vias as a 'new technology'? Just my rant - I feel better, now. :) Ray --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------