PCB Fab House Choices


#1

Hey everyone, not sure if this is the right place to put this, but I think it might turn out to be a “resource” in the end so… shrugs.

I work for a company in the US who rarely does PCB designs and fairly limited prototyping runs of boards. I was wondering who you would recommend for doing runs of ~5-10 boards with a week or two turnaround time that isn’t stupidly expensive.

Since they would be prototypes, they wouldn’t need to have parts installed at all. Most of them would be around 3" x 4" with 4-8 layers. The current one we have is 2.5" x 2.5" and just two layers.

I know that OSH Park is big around here, just thought I’d ask and see who others use. Also I don’t think OSH Park offers green solder mask, which I would like since all of our other PCBs are green.


Simp's build log
#2

One of my favorite sites for comparison shopping different delivery and parameter options is PCB Shopper:

Check that out and see if it fits your need, I’m sure there’s at least one option on there that will fit the bill.


#3

Oh that is a great site! A little sad that there aren’t more fab houses in the US.

What I fine really interesting though is that 4PCB is on there with a fairly good price. My initial quote to them is something like $90 per board! Makes me wonder if I have some really weird feature on my PCB. This is my first time quoting/designing a PCB for real.


#4

Yes, if you have higher copper thickness, a different color than their standard (did you choose “matte green” instead of “green”?) and if you have super small feature sizes, then it would change things. Also is your 3"x4" number a square board? Are you able to share other specs of the board you’re getting quoted?


#5

It’s a pretty simple board. Wondering how I can upload the project files though. I’ve only quoted the 2.5" board for the moment, which is square.

From my understanding this is all pretty standard choices. Attached is the specs I put into the 4PCB site.

On the upside though. BasicPCB is only $78 for the 5 boards. :slight_smile:


#6

Here are my KiCAD project files. There isn’t much to the board thankfully. It’s just a simple DC/DC Converter based on a similar design which we use already for other purposes. If you find any faults, let me know. I’m always curious to learn more about this stuff.

Download Link


#7

I tried pcbway.com for the first time a few weeks back and had really good results. I went with their standard 2-3 day build time, and even got a custom solder mask color which was supposed to increase the build time by a day. I had the two boards I had ordered in 6 days! If you have more than one board they let you add multiple boards to an order to save on shipping which is nice. I came up with $26 shipped for your 2.5 inch board which includes 10 boards and dhl delivery:

If you need the boards faster they have the 24 hour build option for an extra $30.


#8

Jeez, only $30 more for a 1 day turn? That’s nutty


#9

I’ve been using PCBway for production PCBs recently and I’ve had really good luck with them. One of my big problems with other vendors was quoting a shipping date and then missing it. PCBway has not missed a ship date yet.


#10

PCBWay sent my boards to someone in Florida (I’m in Europe) and sent that person’s boards to me… It got sorted in the end with PCBWay re-manufacturing my boards, but it took more than 4 weeks.

/Niels.


#11

Hi @ScottS,

Had a look at your board and I can’t find anything suspect that would increase the price.

Regards,
Niels.


#12

Thanks for the help everyone. Like I said I went with BasicPCB and I just got the boards. They look really nice :slight_smile: More than that even, the footprints that I made fit the parts! :smiley: Always really nice

Black squares are me blanking some information. Ignore them!

I might try out PCBway for my own projects, but I do like the idea of giving some business to the US companies. And since I wasn’t paying for the boards myself, might as well use one that helps out the US.


#13

So I got time to solder the thing up, ignore the awful soldering (although the crooked inductor wasn’t done by me!).

I powered it up though and it seems to have some issues. The output at no load looks great (around 5.01 V), but it seems the output has issues under load. When I put on a 6R load, the voltage drops to ~4.7V and at 2R the voltage drops to ~4.5V.

Thoughts?


#14

Difficult to say without knowing the circuit diagram. What is the type number or resistance of the inductors?

/NIels.


#15

When I get to work tomorrow, I will upload the LT Spice file and the BOM as well. I do wish the forums had a place to upload small documents like that in a zip or something. Ah well.

But the simulation seemed to go okay and I was able to use the correct inductors, they were available in LT Spice. They are the Wurth Elektronik 744770147 WE-PD 1280s.

I do see that they have a series resistance of 0.076R. Which at 2A would be 0.15V drop. But even then, I’m seeing a 0.5V drop at 2A.


#16

I just enabled .zip attachements. You should be able to drop them into the normal response dialog here (or use the upload button)


#17

The 0.076 is typical but it could be closer to 0.1. You also have two inductors in series which will double your voltage drop.

I also notice that the pinout of J1 doesn’t match the text in the box below.


#18

Awesome, thanks!

I’ve uploaded the zip file of the simulation and the BOM so all of the parts are in there.

I saw this. I realized that it got messed up after I got the board back. The connector is put on the back of the board and as a result it’s all wonky.

For the most part, we won’t be running it at max current, although it would be nice to be able to do that without much issue. I did check the output directly at the Vout pin and the same voltage drop was there.

I’m guessing this means that I should try to find an inductor that has a smaller series resistance.

PCB.zip (9.3 KB)


#19

Is your 12V input still at 12V when running the circuit at 3A output? How clean is the (input) power line; any oscillations or excessive (HF) ripple? Same question for the output?

/Niels.


#20

I didn’t scope the input of the DC/DC, but the output post filter was really clean from what I could tell. Not a lot of harmonics, oscillations, or HF from what I could see on the scope of the output. Pre-filter there is a lot of noise induced from the DC/DC though, so the filter is doing it’s job at least :slight_smile:

The power supply I was using though didn’t see any sag on the input at all. Overall the PSU was outputting around 12V at ~500mA when I was seeing ~4.7V at ~750mA.

I did some more spice modeling, and using a 15uH or 33uH reduces the voltage drop by about ~100mV at a 2A load. We are also looking at getting a different DC/DC converter which outputs 5.1V nominal. Therefore if the output sags some, it is less of an issue.