+1 for Elecrow - Page 1
Forum section: electronics / general

author: bson
author_rank: Unknown
timestamp: January 05, 2018, 02:14:31 am
content: I just got a batch of small 4-layers boards from Elecrow. They're only ~50x80mm, so not huge and not super complex, but not entirely trivial either. It's a prototype board based on an 80 pin NXP LPC4078 (ARM Cortex-M4), a TI TLK110 industrial 10/100 PHY in RMII mode (the 80 pin CPU doesn't have the full MII interface), device USB, a USB virtual serial console, 24LC256 EEPROM, an AD5667RBMZ DAC, and just a bunch of ports. On the left I've checked for physical fit of a few connectors (ethernet, two micro USB B, micro SD, and a 14 pin JTAG socket). I doubt I'll use the shrouded 14 pin JTAG connector and will just use plain pin strips instead - the next rev will get a smaller Tag-Connect TC-2050 or 2070.The purpose is to bring back some old ARM7TDMI firmware created for LPC22xx and LPC24xx around 2005 or so; hence the use of an SoC with the same (mostly) peripherals. Just some minor code needed for thread support (save/restore context, trap and exception handling, VIC to NVIC, etc), and the ethernet controller is a bit different.I ordered 5 and got 8.Ordered on the 28th, received the DHL package today the 4th - that's 7 days.Price including ENIG, a paste stencil, and DHL China shipping was US$93.Silkscreen looks very good for dot-matrix; I used 0.8mm designators but could probably go down to 0.65 without trouble. Alignment looks great to me! I left a 0.1mm outline for testing (the uSD card connector) and while somewhat uneven is unbroken on all the PCBs. So, 0.65x0.1 text should be okay.Via tenting is fairly uniform except a small number where the solder mask seems to flowed into the via. No problem really, and absolutely doesn't matter for a prototype.Paste stencil is stainless, 150x150mm, and has both sides on it. (I have some decoupling caps and the odd pull resistor placed on the bottom.) Alignment looks perfect to my eye. Nice!The only error I can see is the USB B connector guide slots are included on the stencil, otherwise no holes appear on it. I'll have to tape over these when pasting, and then manually dab some paste on the largish mounting pads - no biggie, and I'm sure the error is entirely mine since I created the footprint. (It's kind of old and the time things like paste layers didn't enter my mind.) I should have caught it when reviewing the gerbers (in zofzpcb).Here's a happy customer, so far!KiCAD 3D rendering:

author: bson
author_rank: Unknown
timestamp: January 08, 2018, 12:33:41 am
content: On inspection it turns out they were the ones who included the USB B socket guide slots on the stencil, not me. Not a big deal, but it shows there is something manual involved here - which of course is error prone. And here the technician made a booboo. Not sure why they wouldn't simply use the paste layers. Something to keep in mind and even though I'm sure they would fix it and send me a replacement stencil for free it still adds a bunch of turnaround time - I have the board up and running, so a replacement is already irrelevant. Again, not a big deal, just something worth keeping in mind. Red below are drill, grey are top + bot paste.