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After a brief delay sorting everything out with the courier (who apparently hasn't yet advanced to a level of hand-eye co-ordination that allows him to knock on a door or press a button), we finally got our first batch of PCBs for the LPC2148 Reference Design along with a simple breadboard we whipped up to make prototyping a bit easier.  It's the first largish order we've placed with PCB Cart (we'd been using Gold Phoenix previously), and it was a trial run for us but their service was excellent, and the boards were not only well manufactured but they even cut them all out for us (which was unexpected).

They were very well packaged (in small air-sealed bags with dessicant and protective foam), and had a nice overall finish.  The only unfortunate surprise for us was that PCBCart seems to lay down the ink for the silkscreen a bit heavier than we were used to with Gold Phoenix.  We generally used a 12% ratio for larger text with Gold Phoenix, whereas you probably want to stick with Eagle's default 8% ratio for PCBCart.  We'll play around with this a bit on the next order and try to get some more empirical data.  On the whole, though, we're exceptionally pleased with the entire process from ordering (straight-forward) through to validation (quick with clear communication on their part), manufacturing and delivery (on time ... for their part).  Plus the prices are more than fair.  (It's worth noting that if you reorder an existing design that you've had manufactured with them you don't have to pay the tooling fees again, which on runs of 50-100 boards is often half of the cost.)

Here you can see a photo of the bare LPC2148 PCB (click on the thumbnail for a larger image).  The silkscreen issues are only visible up close and on the smaller text (you can't really see it in this photo), but that's really not the fault of PCBCart either.  With any manufacturer (of just about any type of product) you need to learn what their own quirks and peculiarities are, and we were carrying over a problem we've had with Gold Phoenix to a new supplier.  Had we left the silk screen ratio at Eagle's default (8%) the text may have come out a bit better.  As we mentionned above, we'll try with the next order and report the results and some suggestions here.

These boards were all produce using PCBCart's "Standard" service (0.4mm minimum drill size, 8mil traces/spaces, though we cheated a bit on the annular rings and used 10mil instead of the stated minimum of 12mil/0.3mm ... no one seems to have noticed or complained, though).  We've also sent out some prototype boards with 4mil/0.1mm annular rings (which required extra tooling costs and slightly increased the per board cost, but allows far more freedom routing complex boards).  We'll post the results once we get the boards in.

Not long ago we posted a Design Rules Check (DRU) file for Eagle for PCBCart's Standard service (8mil/0.2mm minimum traces and spacing, 12mil/0.3mm annular rings, and 0.4mm/16mil minimum drill size).  We've been working on some larger boards with 200+ pin ICs since then, and routing them is a definate problem with so many large vias on the PCB.  To work around this, we've decided to reduce the size of the annular rings (the metal ring around the drilled hole on your vias), as well as reducing the minimum drill size.  We've put together two more DRU files for Eagle to check against these tighter limitations:

PCBCart: 0.3mm holes 0.1mm annular ring

	Description	Version
	Minimum traces/spacing: 8mil/0.2mm Minimum annular rings: 4mil/0.1mm Minimum drill size: 12mil/0.3mm	0.1

PCBCart: 0.2mm holes, 0.1mm annular rings

	Description	Version
	Minimum traces/spacing: 8mil/0.2mm Minimum annular rings: 4mil/0.1mm Minimum drill size: 8mil/0.2mm	0.1

We tend to use a mix of both European and Chinese manufacturers for our PCBs, with the decision usually depending on whether we need the board quickly (which usually means a European manufacturer like PCBPool) or inexpensively (most often PCBCart or perhaps Gold Phoenix).  For single board prototypes, the prices all tend to be in the same ballpark (when you keep in mind shipping costs and delays, taxes and duty, etc.).  If you want to produce more than 10 boards, though, the Chinese manufacturers start to be very competitive in terms of pricing, and at 100+ boards there's really no contest financially.

PCBPool already offers a DRU file for Eagle which you can download here (look for "Eagle DRU File"), but to make it easier to detect any potential problems when sending Gerbers off to PCBCart, we've made a design rules file for their "Standard PCB" service, which has the following technical limitations:

1. 0.2mm (8mil) traces/spacing
2. 0.3mm (12mil) annular rings* (see note on this below)
3. 0.4mm (16mil) minimum drill size

PCBCart is able to produce boards with much tighter technical specifications than this, but you pay a premium for that so we usually stick to the standard settings unless there's a pressing reason not to. 

To use the DRU file, simply download it and save it to the DRU folder where Eagle is installed.  Once you have finished your board layout (or want to test the work you've done so far), you can click on the DRC icon , load the appropriate DRU file, and run the tests.  If any errors are detected, Eagle will inform you of them and you can double-click on the warning to zoom into exactly where the problem is on your board.  You should always make sure that your board passes the DRC check before sending it out for manufacturing.

PCBCart "Standard Service" Design Rules Check (DRU) for Eagle

	Version	Release Notes
	0.1	Initial Release (Beta)