SparkFun Forums

[InactiveUser001]

ATX connectors are fine for the current required and IDC headers can be found to make it easier to make the cables.

Although I would question why you are increasing the cost of the board by using double sided placement and silkscreens?

Is it to be manufactured as a product? If it is it will require 2 x solder paste screen, 2 x placement setups - 2x runs through the placement machine and the PCB is costing more.
Or is it just a one off?

IMO All the res/caps on the underside can be fitted on top side leaving only the ATX connector - is there a reason why it is on the other side?

IF manufactured are you expecting to use optical inspection to test this? If so then those sets of 3 pads that have the big track through them will appear as a short and will require separately programming in to indicate they are not, it is common practice to route out of individual pads before joining them together. If not then never mind.

How are these transistors switching 2A? I only see 2 connections on them? Are you using via in pad ? (more unnecessary cost.)
Or have you a considerable current coming out of the ic's to the transistors? (I cant see your schematic as I dont have eagle).
If so then the IC's would be better closer to the transistors.

You still have plenty of acid traps that can easily be done away with.


EDIT: OK I have eagle now - and although I am no expert at driving it - I cannot see connections to ground on the transistors or capacitors etc?
Is this some hidden connection in Eagle?

[techy101]

This board is a one-off controller for a LED cube project, and the cost of the is fixed due to my choice of manufacturer ($33/board double sided up to 60 in^2). Part of the reason for double sided is to get some practice with multi-layer boards instead of just single sided.

It's not just the ATX connector on the reverse, it's also the IDE headers and power supply connector.

I have no clue about the optical inspection but I will move the connections outside of the pads to correct this potential error.

The transistors, capacitors, resistors, etc... have the net name for the GND pads named to GND. The ground planes are also named GND, so this will create the connections automatically. They are hidden at the moment for visibility, but hitting the ratsnest button should change the views to show the ground planes/connections.

Are the acid traps the 90 degree angles? I'm probably being completely blind, but I can't quite figure out how to run a bus like that without those hard angles.


And yet again, continued thanks for all of the helpful feedback.

[Ross Robotics]

The large IC is actually a set of headers for an Arduino Micro so it can just be sandwiched on as we already own it.

Those are your words. So you are going to make a plug that will connect the Micro.. I wouldn't call that "sandwiched."

@mattylad He is getting the boards done at OSH park. It's 2 sided and they don't charge extra for 2 sides. They only fab boards of 2 or 4 layers.. They also don't care that there is vias in pads. It doesn't cost extra. The boards from OSH park are charged by the size, not the complexity.

[InactiveUser001]

I see now I have it in eagle, I have hit auto and its poured the top copper and connected the pads.

The acid traps are the 45 degree angles into a straight track. This creates an angle that is "less than 90 degrees".
Simply enter them straight as a T junction.
Signal is RCK.

If you move the via on the DATA line right until it meets the vertical track then the bottom track on RCK can stay on top instead. IN fact bring the via down and the via/bottom track on DI11 can be removed. Perhaps bring the data line on top so its not splitting the plane underneath as much?


Look at the thick VCC track and review the GND return - it appears to be very thin as its split by SCK.

Ok I give up - I'm not understanding this eagle very well lol, best not save what I have looked at. Back to the manual

Plugging the arduino in is simple, use a SIL header and socket set - done it many times in the past.

[Ross Robotics]

Ok, attached are images to illustrate acid traps. Red arrow pointing to the target. My Photoshop skills are lacking..

Click on images to enlarge.

[Ross Robotics]

You stated that you had some DRC errors? I am not getting any.. Are you using OSH Park's DRU file?

I agree with Matty, the ground return isn't very good since the SCK line does go through the middle. See if you can re-route the SCK line. But, you may have enough ground vias to compensate.

I would be prepared that your first run boards will have problems. Doesn't matter how may times I triple check mine, 99% of the time, I find something wrong. And the problem usually consists of having to run the boards again. My last boards, I had to make a part library from scratch and had a 1mil error in the stop mask which made a regulator short to ground. I had to re-fab the board. Took 1 min to fix, but cost 2 weeks of fab time..

[techy101]

The large IC is actually a set of headers for an Arduino Micro so it can just be sandwiched on as we already own it.

Those are your words. So you are going to make a plug that will connect the Micro.. I wouldn't call that "sandwiched."

My bad, I completely blanked on having written that. I had been confused thinking that question was somehow related to the ATX connector.


I'm actually using Advanced Circuits (aka 4pcb) partly because as a student I can get a 1 board minimum with the $33 and pretty good specs, and partially because they have a manufacturing facility here where I live. It's not the facility that will make this board, but still feel good supporting companies who partake in the local economy.


I'll get looking at the suggested updates to the board, and try to fix problem areas. I know that it's likely to have issues after manufacture, but the real reason for this project is to learn PCB design which is why I'm hanging around this part of the internet. I'm a computer engineering student with a hardware focus, but they don't really teach this stuff to the CompE's or the EE's as part of the regular curriculum; something about it being more of a technician skill... Given this, to learn it I've got to try and learn it outside of the classroom.

The DRU errors were in a previous version, the one from which I pulled the last set of photos. They had been repaired prior to uploading the zip file.

@mattylad, Eagle has been my first intro the PCB design, but I'm not poking around with a demo version of PADS (to little avail) and just picked myself up a copy of Altium Designer because the student rate is so darn good. My hope is to move beyond Eagle pretty quickly, but for now it's my go to.

[Ross Robotics]

Ah, ok. If you need high quality boards, check out OSH Park sometime.

I think Eagle is all one would need in a CAD program. I do have a copy of Altium just because of the flex board feature. Haven't actually used it yet, but I will soon.

[InactiveUser001]

So far I have not come across a current PCB layout course.

I did once hear of a college doing it in league with mentor however I don't know if they still do.
IMO The whole process from initial layout to actually obtaining the boards etc could do with being a complete course, if the PCB program manufacturers would help fund a college that did this then I think they would get more sales and we could have more PCB engineers - but they don't and its a dwindling skill.

Good on you for your efforts, for the research etc and taking on board whats been said. I see nothing wrong with starting off with Eagle, you can move up onto bigger packages later on in your career.

And just remember - for everyone that has an expert opinion - there is someone else that has an opposite one

[techy101]

Just got the board assembled. Unfortunately it doesn't look that good in the pictures as there is some residue that the camera really loved to pick up. The back side didn't reflow well at all, but I'm chalking that up to a lack of experience as I just built my oven recently; the top side did much better. I won't be able to test it for a week or two to find out if it actually works, but hopefully it does.

Here are a couple of pictures.