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Cheap PCB production

Started by Phil, June 14, 2016, 09:05:41 am

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Phil

Hi. It seems you have tried a few different PCB manufacturers. I wondered if you would share your experiences of the different ones you tried and which ones you would use in which circumstances?

Thanks a lot for your site. You inspired me to try SMD work and designing my own PCB!

Andy Brown

Hi Phil,

For 2 layer boards I've tried Seeed, ITead and Elecrow. Quality-wise they're about the same and I wouldn't be surprised at all if they all contracted to the same manufacturer. I settled on ITead because on one order I made a mistake that I only spotted after submitting the design. I emailed them and they contacted the board house and held the order while I submitted corrected Gerbers. Good service like that on a small $20 order deserves to be rewarded so they got my custom from then on.

For 4 layer boards I've tried ITead and PCBWay. The quality of the 4 layer boards is, I think, markedly better than the 2 layer boards when compared at the limit. The drill accuracy is better - they tend to hit closer to the center of the via pad. The solder mask aperture positioning seems to be better as well. When I received my Nanocounter boards back from PCBWay I was very pleasantly suprised to see that the soldermask was intact between the pins on the 0.5mm pitch QFN40 package on every board in the package. Those little slivers of soldermask are only about 3.8mil wide.

4 layer boards are in general a lot more expensive than 2 layers. It's not too bad at 50x50mm but a set of ten 100x100mm will run to about $50 plus shipping, compared to about $11 at Elecrow for the same size in 2 layer format. I've settled on PCBWay for 10x10cm again because of service. I've played email tennis with them asking questions about layer stackup and dielectric characteristics and each time they've quickly answered the questions.
It's worse than that, it's physics Jim!

Phil

Thanks for sharing your experiences. I think I will try Itead.

I probably would have gone with OSH since they have a KiCad upload feature which makes it very easy for beginners like me, but for the price you get only 3 boards instead of 10.

With Itead, I need to figure out how to plot the different files and rename it to the right specifications.

I need to investigate if KiCad has any feature that can automatically prepare to specific manufacturer restrictions and/or if there is a script which can automatically create as doing it by hand each time is not convenient.

Andy Brown

For a 2 layer board most houses will just require (top layer) GTL, GTO, GTS and (bottom layer) (GBL, GBO, GBS) as well as the TXT drill file. They'll also want the board outline to appear on one of the layers. During the design I have the board outline as a 2 mil trace on a separate mechanical layer and then during the export I use an option to include that mechanical layer on all exported files. All the houses seem to be happy with that.

Before sending anything anywhere I preview it in the free ViewPlot 1.5. The author of ViewPlot seems to want us to use and pay for a much more expensive 2.0 version now. Don't bother. 1.5 is perfect for our needs. Just load up each side individually to preview what it'll look like. e.g. First load up GTL, GTO, GTS and TXT and zoom/scroll around to check it (it helps to change which layer is in focus using the on-screen selection box). Then restart the program and do the same for GBL, GBO, GBS. I've found the odd error like this and it also helps draw attention to crazy routing decisions that are best revisited before you commit to copper.
It's worse than that, it's physics Jim!

Phil

Thanks for the tips, they are much appreciated. I think I'm ready to go now except... the OCD part of me refuses to submit it while I have half the maximum 5cmx5cm unused!  ;D

I'm now busy thinking what else I can populate the board space with so that even if the main part is a total failure, I can still make use of the rest as SMD breakout, testing PCB footprints for various components etc.

KiCad comes with a GerberViewer, but maybe it also makes sense to use another app to sense check it. You mention version 2.0 is more expensive, but it according to the page, if you use the Download version it is read-only but free! I guess for checking, this is fine.

Andy Brown

Have you remembered to add screw holes either for feet or for mounting into a case?
It's worse than that, it's physics Jim!

Phil

Thanks! I did :)

In the end, I made 2 different PCB designs and sent them to Itead. Let's see how it goes. If they come back OK and you send me your address, I can send you a copy of each :)

Phil

I noted that in both uploads, the system 'failed to analyze the gerber files'. Hopefully nothing drastically wrong... :)

Phil

Here's a preview. It gives what I presume is some warning so I guess something is wrong, but I chose to ignore it and I will see whether it still works or not...

Andy Brown

Looks like a good first design you've got there. The one thing that does stand out to me is that C3 is rather close to that pin header. If C3 really is the diameter indicated in the drawing then you may find yourself bending the leads away a little to move it away from the end of the header.
It's worse than that, it's physics Jim!

Phil

You are right. C3 was originally also a SMC, but I changed it at the last minute to THT as I didn't have the right SMC capacitor on hand but had loads of THT ones. I didn't care too much about the closeness as I will bend the capacitor over to the right.

I actually plan to have the low numbered pins as male pins mounted on the underside and just have the last few pass through pins as female mounted top side, so there will be no issue with space on the top board.

Thanks for your feedback, I'll send you a copy of the board :)

Andy Brown

June 25, 2016, 02:48:53 am #11 Last Edit: June 25, 2016, 02:51:46 am by Andy Brown
Quote from: Phil on June 24, 2016, 05:23:49 pm
You are right. C3 was originally also a SMC, but I changed it at the last minute to THT as I didn't have the right SMC capacitor on hand but had loads of THT ones. I didn't care too much about the closeness as I will bend the capacitor over to the right.

Having tried surface mount aluminium electrolytics I now avoid them when using a reflow oven because they can end up looking like this. Apparently it doesn't affect their performance which I find to be quite surprising. Nevertheless I err on the side of caution and use either through-hole electrolytic or tantalum for the larger size capacitors now.

Quote
Thanks for your feedback, I'll send you a copy of the board :)

Thanks, you might have to tell me what it does though :)
It's worse than that, it's physics Jim!

Phil

In case it is useful for anyone else, I used this small script to do the renames:

#!/bin/bash
cp *-B.Cu.gbr ITEAD.GBL
cp *-B.Mask.gbr ITEAD.GBS
cp *-B.SilkS.gbr ITEAD.GBO
cp *-Edge.Cuts.gbr ITEAD.GKO
cp *-F.Cu.gbr ITEAD.GTL
cp *-F.Mask.gbr ITEAD.GTS
cp *-F.SilkS.gbr ITEAD.GTO
cp *.drl ITEAD.TXT

Phil

The boards arrived back! I'm pretty impressed with the turnaround time. I even managed to assemble the 2nd one and found that it worked! The first board, I can't assemble yet as some components I need to still pick up...

Andy Brown

Nice one Phil. It's a very satisfying moment when you apply power and it works.
It's worse than that, it's physics Jim!