SparkFun Forums

[Chewie RFC]

Hello SparkFun,

I've created my first ever PCB. I studied Electrical Engineering in college, but I commissioned into the Navy upon graduation (2003) and I have been flying ever since. I have recently re-discovered electronic circuits as a hoby and have decided to make a simple AM radio receiver for my first project. I've already prototyped the design on a breadboard and it works well. I've decided to put it on a PCB, since I never even did that in college. Attached is a screenshot of the PCB design, using Eagle. Any criticisms, comments, or tips would be great. Thanks!

[mattloto]

Thats pretty organized and neat, especially for a first design!

The only thing is about the font for the labels. Make sure to set the font to Vector or the silk layer will be offset a little. I can't tell for sure if you're using it or not from the image, but just look out for that.

[Chewie RFC]

Thanks! That's actually v1.3... it took a few days to get there. My v1.0 was not nearly as good. Thank god for those SparkFun tutorials! For the vector font, thanks for the heads-up. I saw that in the SparkFun tutorial as well. I re-verified to be sure!

[Chewie RFC]

Oh, another question: I'm using BatchPCB... all my traces and ground pour are on the bottom layer. Do I really need a top solder mask and copper layout?

[JonChandler]

Very nice job for a first layout. I came across a PCB Design Tutorial by David Jones of EEVBlog fame the other day. It's nicely written with much valuable information. It's recommended for anybody designing boards.

One of the points he makes is that boards should just look nice. Yours scores big on that point.

[Chewie RFC]

That's a great PDF, thanks!

[SpikedCola]

Oh, another question: I'm using BatchPCB... all my traces and ground pour are on the bottom layer. Do I really need a top solder mask and copper layout?

Excellent job on the layout! It looks very good for a first-timer! To answer your question, no, you don't need the top copper or solder mask, but Im not sure how BatchPCB handles jobs which lack these files. For that reason it may be better to send them everything, even if you dont need those specific layers, to avoid any problems on their end.

Cheers! Happy routing

[analogon]

Oh, another question: I'm using BatchPCB... all my traces and ground pour are on the bottom layer. Do I really need a top solder mask and copper layout?

Understand that top silk and top copper are included in the price. It is more common to put the silk screen on the top for parts placement, rather than on the bottom. Plus, with BatchPCB, putting your board outline in the top copper or top silk is best. I like a zero width shape for that.

It is important that you not send the layer (probably your assembly layer) that shows the pot and switch outlines outside of the board shape to BatchPCB.

I would use a larger gap in the pads of your round capacitors. This will make your had soldering less critical. I like to make the positive pads on electrolytic caps rectangular. I would move your '+' signs away from the pads. Silk screening over pads will not print; the pads have priority.

Is that a header/connector for the battery? If not, and if you are soldering wires, I would increase the separation. If you are using a connector, then no problem.
I wonder about the two pads labeled "tuner". That function would normally be part of a receiver, so I wonder what kind of device that is.

Is this is a learning tool for you in making boards, I would try to fit this to a smaller board. If it is a training board for students to probe, then the big spaces should be useful.

[Thric]

Thats a very nice looking board. Nice work. I have never used BatchPCB before so I don't know its restrictions but a great guy that I have used so far is: http://dorkbotpdx.org/wiki/pcb_order The boards that I got out from there are of amazing quality and the best thing is that it is really cheap and you get three copies. the only downside is that the next order is only going to start Dec. 6th.

[Chewie RFC]

Understand that top silk and top copper are included in the price. It is more common to put the silk screen on the top for parts placement, rather than on the bottom. Plus, with BatchPCB, putting your board outline in the top copper or top silk is best. I like a zero width shape for that.

Oh, my silkscreen is on top, as per standard. I was just wondering if a top solder layer and solder mask was of any use for a bottom solder design. I'll just keep it.

It is important that you not send the layer (probably your assembly layer) that shows the pot and switch outlines outside of the board shape to BatchPCB.

Already QA'd that. That would be a blunder!

I would use a larger gap in the pads of your round capacitors. This will make your had soldering less critical. I like to make the positive pads on electrolytic caps rectangular. I would move your '+' signs away from the pads. Silk screening over pads will not print; the pads have priority.

Good to know, thanks. The polarized caps come from a library by Panasonic, which are the make of the caps I'm using. Maybe I'll make my own. The 3.5mm jack and pot are both my own parts.

Is that a header/connector for the battery? If not, and if you are soldering wires, I would increase the separation. If you are using a connector, then no problem.

It is, and I do intend to use a connector.

I wonder about the two pads labeled "tuner". That function would normally be part of a receiver, so I wonder what kind of device that is.

The tuner utilizes a very large and heavy variable capacitor (in parallel with a loopstick). I didn't want to add that to the board. I'm not going to put this in a case, I'll mount everything on a piece or wood or something else to show off the "guts", hence the separation. As for the device, it's a simple AM receiver. Two-stage RF amplifier, envelope detector, single-stage AF amplifier.

Is this is a learning tool for you in making boards, I would try to fit this to a smaller board. If it is a training board for students to probe, then the big spaces should be useful.

It is a learning tool for me making boards (and getting back into electrical engineering). I kept everything spaced out for my own learning purposes and ease of tracing/id'ing parts of the circuit. My next radio receiver (FM, superhet), will be much tighter.

Thanks for all the tips, I very much appreciate them.

[Chewie RFC]

Thats a very nice looking board. Nice work. I have never used BatchPCB before so I don't know its restrictions but a great guy that I have used so far is: http://dorkbotpdx.org/wiki/pcb_order The boards that I got out from there are of amazing quality and the best thing is that it is really cheap and you get three copies. the only downside is that the next order is only going to start Dec. 6th.

Thanks for the link. I have it bookmarked. It's more expensive than BatchPCB, but if that doesn't work out for me, I'll check out this guy. Thanks!

[analogon]

Since you are learning, I suggest you add some surface mount parts. You solder them with something called solder paste. It is not just flux. It is finely powdered solder mixed with a sticky flux. You could put surface-mount pads in parallel with some of the thru-hole parts to let you use either, or to trim a part.

Note that with BatchPCB, they usually send twice as many boards as you order.

[Chewie RFC]

Since you are learning, I suggest you add some surface mount parts. You solder them with something called solder paste. It is not just flux. It is finely powdered solder mixed with a sticky flux. You could put surface-mount pads in parallel with some of the thru-hole parts to let you use either, or to trim a part.

Note that with BatchPCB, they usually send twice as many boards as you order.

That's a great idea, thanks! I saw some of the SMD tutorials on here, they seem useful.

I still think it's funny that I never made a PCB in college.

[Laen]

Oh, another question: I'm using BatchPCB... all my traces and ground pour are on the bottom layer. Do I really need a top solder mask and copper layout?

I don't know specifically about batchpcb's process, but in general you'll want a top soldermask layer, otherwise the entire top layer will be coated with soldermask, and it may go into the holes.

Since your don't need plated holes, you don't need to put pads on both sides of the boards, so the top copper layer is probably not needed.

From a "manufacturability" standpoint, it's best to have pretty much the same percentage of copper coverage on the top and bottom layers, since that helps hole plating. Of course, as mentioned earlier, you don't need that, but keep that in mind for future boards.

As you work on this, try printing out the board at 1:1 scale on regular paper every so often. It lets you see what the sizes are really like, which is difficult on the screen.

[Chewie RFC]

Well, I received the PCB and it's GREAT. I will definitely order from BatchPCB again. I soldered everything together and it functions perfectly. In fact, it functions better than on the protoboard, which makes sense seeing as it is an RF circuit.