Test Board
 

I don't know if this chip is a good idea. Its just too small. The trace and space is TINY. I think since it will require a CPLD, it would be better to write a refresh block and use cheap LARGE DRAMs.

http://www.stockly.com/images4/08041..._schematic.jpg

http://www.stockly.com/images4/080419-PSRAM_PCB.jpg

Hey Grant.

You use WinQ CAD? What size traces did you use? 8 mil is about as small as we can go without getting a price penalty.

After actually seeing that pic we may be forced to go 4 or even 5 layer, without Ground or Power plain.


Henry

Trace width costs
 

Given the .75mm ball spacing

Gold Phoenix for example charges

155 Sq inch
2 layer base cost $99
6mil/5mil/4mil trace width/ clearance(2layers) $20/$40/$60

4 layer base cost $330
6mil/5mil/4mil trace width/ clearance(4layers) $40/$80/$200

If our breakout board was 4 sq inches for example that would yield about 38 peices so below is the cost per piece for reference

Trace widths
8 6 5 4
2 layer 2.55 3.07 3.58 4.10
4 layer 8.51 9.54 10.58 13.67


Since I have ordered with them before I might be ablet to get another 10% off

Yikes! Now I see why those VFBGA Adapters quoted from Aries are so much.

Grant: What are the clearances on your design? I also assume that pic is two layers? Give me some GERBER files and I can get some price quotes. Can you also post a pic of a blow up on the PSRAM area so I can get an idea as to the trace spacing and layout?

Glenn: I've been using QualityPCB.com. They have had the best prices for 2 layer stuff that James and I have found.

I just ran through the quote system for a panel the same size as GP and it came out to $130 and then they will add shipping to that. and it seems I have to panelize the board myself.

GP is $99, they panelize the board if it is repeat of same pcb and it includes shipping

You might want to give them a try - http://www.goldphoenixpcb.biz/special_price.php

Tell Shane that Glenn from a2retrosystems sent you .... :o)

Hey Glenn.

Thanks for the info. I do have one design I need quoted right now. I'll email him and see what prices he gives me.

I know I asked them for a quote just about a month ago and they were a bit higher. Think James had the same experience too. Maybe it's just the little panel stuff they have the best price with. Hard to say as it seems some guys specialize in one thing, yet others give better prices on something else.

I'll post the prices here and let you know who I went with.

Yeah ... my board is square so the yeild is likely higher giving a better price. Doesn't hurt to shop around.

Hmm actually for 1 panel GP is cheaper but @ 2 panels QualityPCB does come in %25 cheaper .. I will certainly get them to quote for me next time.

Thanks for the pointer Henry

The board I made was just a quick and dirty 30x2 .6" wide DIP adaptor.

The trace/space was 5mil. At 6.25mil it would end with 28 traces unrouted, 5 mil would route almost immediately. The board was 4 layer as shown.

The price penalty of using PSRAM might not be worth it. SDRAM would be harder, but pay for itself in the end.

A lot of the commercial designs out there are able to use 6 layers on small embedded boards.

Humm.... I would tend to agree from what I'm seeing in the prices. Not that anything HAS to be this PSRAMs of course.

Now back to square one. Anyone have a high density SDRAM IC in mind? TTSOP I would assume?

I bet we can even find a stock Adapter too then.

Why would we need an adapter for a TSSOP?