Sunstone Circuits PCB "Incapabilities"??

Hello Everyone,

I'm doing a 6-layer PCB with two 676-pin 1mm spacing BGAs. I got this sponsorship deal with Sunstone, so they are paying for my degree project since I am entering it into a national competition.

I ran into a major problem! I really didn't think 1mm BGAs were very advanced, but apparently I cannot use this company at all to do this. Their annular ring specification is 8.5mils and their minimum via is 8mils. This means that I have a 25mil or 0.98mm pad. I called and they said that they are incapable of doing anything smaller than a 8.5mil annular ring.

http://www.sunstone.com/pcb-capabilities/manufacturing-capabilities.aspx

Am I missing something here? Most manufacturers spec. annular ring separately for vias and pads? such as

http://www.4pcb.com/index.php?load=content&page_id=15

Or, did I get someone on the phone that didn't have a clue?

I'm pretty stressed because I had a golden ticket for a 500$ PCB, now it seems that I can't cash it in because they are in the stone-age with their PCB capabilities.

Steve

Just an update, I ended up shrinking the annular ring to 7.95mils and I will have to see if they can run it as given. I read on another page that their actual spec is 8mils, but I suppose they leave a margin for the proto service of an extra 0.5mils.

Steve

Ahh, wait a sec, Steve...
1 mil = 1/1000 inch = 0.001 inch = 0.0254 millimeters
1 millimeter = 0.0393700787 inches, or 39.3700787 mils

Go back to your original size so you can still see the pads

@SgtWookie
The OP wants to put a via in between the balls of the BGA so he can fan out the connections.

@OP
Maybe Advanced Circuits (the other link) could help you out. They used to sponsor students for competitions. Another company to check is DDi. I never realized Sunstone had such a hard time with that-- I wonder what the problem is. Maybe their registration capability is not as good. I am pretty sure I have sent them boards in the past with 5 to 7 mil annular rings. For holes that small, I'd specify that they can plug them and tent the vias if it is easier for them.

Wookie! These are tiny tiny pads New technology isn't friendly

nanovate,

Thank you sir Their registration is the same spec as advanced circuits, I'm very confused about it too. I will ask them if they can plug vias, that would probably ensure conductivity anyways. I have asked Advanced Circuits for help, but they're more interested in the big dollar projects like race cars and stuff. I will look into DDi though. I really hope that this works out, it'll be a bit embarrassing if my project fails because the boards can't meet basic modern specs.

Steve

They both recommend at least a .007 -.010 pad set larger than the drill hole to guarantee there is solder into the hole barrel once the hole is filled. You shouldn't go any narrower than the hole size or you risk holes void of copper. The pad is placed to seat a solid through-hole connection and their recommendations help assure this. Most any hole under .016 will be plugged as long as there is some sort of pad on the via. Its simple enough to plug the holes yourself if needed.

Did you check out this link?
http://www.sunstone.com/products-se...oards/drill-file-pad-clearance-setup.aspx#pad

btw - I tried to use Advanced but they aren't as student friendly as Sunstone. If you have $500 from Sunstone, that's way generous, I got $100 for my senior project and Advanced only wanted to give me a pizza coupon! Who do you remember when you you leave school? I use Sunstone all the time and have been really happy with how they treated me when I was a student. Now I use them exclusively.

Good luck with competition and getting your BGA to work!

Hi CamCommando,

I certainly do appreciate their generousity and will consider it when I am an engineer. The $500 was granted, since it is for a national competition. I like advanced circuits too, they have given me some good discounts in the past. They have a much better annular ring specification of 5mils. I actually did a 256-pin FPGA in the past with a 4-layer PCB from them, it was not a problem to run 10mil drills and 20mil pads. I checked out that link, but couldn't believe how large I had to make the pads. They need to be more competitive in their technological offerings.

The problem with the ~24mil pads is that I cannot run a trace between two of them side-by-side. I had to give up on routing an MRAM IC that I wanted to use in case I didn't have enough memory. I switched to a fast serial FLASH IC instead, so all is well. Thanks very much for your bid of good luck!, it may be needed I'm confident that the board will turn out okay, but I am worried about my design a bit.

Steve

Its been driving me crazy and found this article: Top-ten Reasons for Via in Pad

I also found this article with good visuals: [URL="http://www.screamingcircuits.com/Portals/0/documents/Via_In_Pad_Guidelines.pdf] Via in Pad Guidelines [/URL]