Demo Board from ITead Studios for a PCB Design Tutorial - Page 1
Forum section: electronics / projects

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: April 13, 2011, 07:48:53 pm
content: Woohoo....my boards from ITead Studios arrived today. I designed this as a handout and design aid for a tutorial I'm going to present at the local hackerspace in Seattle on using Eagle to design boards for commercial fabrication.The front side of the board has various package types and sizes, resistor and capacitor patterns and a number of hole sizes. Hopefully, this will help prevent others from making some of the mistakes I have over the years! This is actually the worst board of the lot and I am delighted! The 0.5 mm pitch TQFP package in the lower right corner has some scratches where the manufacturer cleaned up the clearances between the pads. This perfectly illustrates one of my points: "Don't push the limits of the technology if you don't absolutely have to."The boards were delivered three and a half weeks after I ordered them. There was some confusion regarding the Gerber files as I didn't think to mention that there were no traces on the top side and few on the bottom.

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 13, 2011, 08:33:41 pm
content: I've seen a few versions of these types of boards and I think it is a great idea. For someone like me who is getting up from the grid board hand routing to manuf. PCB, a references like this would be great.Would you be willing to share the Gerbers?

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: April 13, 2011, 09:31:48 pm
content: I'd be happy to share the Gerbers. I'd like to know where they're going though, so send me a PM with your email address and I'll send them.I think we'll also make the boards available through Metrix Create:Space in Seattle if you just want one or two copies. I'll post here when we have the details about this.

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 13, 2011, 09:36:47 pm
content: I'll see if you are going to offer them first, otherwise I'll PM you when I start deciding to go custom PCB route. It would be interesting to send the same sample through a couple different board fab houses to see the differences.

author: Bambur
author_rank: Regular Contributor
timestamp: April 14, 2011, 01:25:11 pm
content: Jon, how did you make the corners of the board rounded?

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 14, 2011, 02:51:12 pm
content: Quote from: Bambur on April 14, 2011, 01:25:11 pmYou should just include that in the routing instructions for the board maker. With routing, you can specify about any shape you want.

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: April 14, 2011, 02:52:15 pm
content: Quote from: Bambur on April 14, 2011, 01:25:11 pmSome cheap....errrr....inexpensive.... board fabrication deals include routing to shapes and other only provide square boards. Since ITead does include routing and since this is kind of a "hands-on" board, rounded corners seem like a nice feature.In Eagle, you draw the board outline in the dimension layer (layer 20 I believe) but it eventually ends up on the silk screen layer when you run the CAM job to produce Gerbers. The outline in the silk screen is what the board will be routed to. This did not require any other communication than the standard Gerber files.If you wanted an unusual shape, some additional explanation might be a good idea just to prevent confusion.Regarding making this same board at other sources, I worked up a chart of board cost vs. lot charges for six vendors from myPCB Fabrication article. These are sources that I have used or I am familiar with. The chart shows that ITead isn't necessarily the cheapest cost per board - I can get boards 20% cheaper from PCBCart...if I spend nearly $200 and order 75 boards! ITead Studios really does change the game for small quantities of low-cost boards.

author: Bambur
author_rank: Regular Contributor
timestamp: April 14, 2011, 08:42:05 pm
content: Awesome info, Jon. Thanks a lot!!

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 15, 2011, 02:19:36 am
content: I agree. I didn't realize anything like ITead Studios was available. I had not expected to order PCB boards for many projects, but with these costs that will change. Also might get me into surface mount faster. This is now at a price level that a hobbyist can handle.

author: lebeno
author_rank: Newbie
timestamp: April 15, 2011, 08:49:21 am
content: I think the graph would be more clear to me if it included a row with the number of boards in that graph. Or am I overlooking that information?Quote from: Jon Chandler on April 14, 2011, 02:52:15 pm

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: April 15, 2011, 11:25:52 am
content: Quote from: lebeno on April 15, 2011, 08:49:21 amI totally agree lebeno! The graph shown was about the third iteration already and I didn't see any way to make Excel cooperate with me in adding another row to the table. The lot cost can me divided by the board cost to determine the quantity.The chart is for a 10cm x 10cm board - because of the way each service handles board sizes, the situation will change for other sizes and quantities. Also, each service offers different features. Some may only only rectangular boards (i.e., no corner routing) while others may provide silk screen only on a single side. Thus, this is a rough comparison showing some possibilities. When ordering boards, check for current pricing and that all the required features of the board are supported.

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 15, 2011, 12:59:44 pm
content: I would go ahead and use the vertical space to print out the name of the service, rather than a lookup table. Much quicker to read. You can also then include the board count in the name. "iTead Studios (10x)"Making the graph shorter by the height of the vertically oriented text will still make it easier to interpret. Otherwise, make the legend have the fab companies ordered by the number. Seem odd to have to scan the list to find which is for #1, #2, etc.Regardless, great info.

author: lebeno
author_rank: Newbie
timestamp: April 15, 2011, 02:58:16 pm
content: Quote from: Jon Chandler on April 15, 2011, 11:25:52 amThis is my attempt at a better graph.

author: Laen
author_rank: Newbie
timestamp: April 15, 2011, 04:25:42 pm
content: Quote from: Jon Chandler on April 15, 2011, 11:25:52 amYeah, 10cm x 10cm * 10 copies is the optimal size for an iTeadStudio order. They'll definitely come out ahead on cost for that size. If your board is any larger, or much smaller than that, others will start to win.Ladyada has a nice PCB Cost Comparison calculator that takes size and quantity into account, since those are obviously very important to figuring who your cheapest option is.http://www.ladyada.net/library/pcb/costcalc.html.I'd say that cost isn't everything, though. Quality matters, and those scratches between the pads of your .5mm TQFP are pretty lame. Those should be .2mm (7.8mil) gaps, and they advertise 6 mil minimums. You're 30% past that. To their credit, they _did_ fix it. Did they fix it on all 10 copies, or only 5 of them?(Disclaimer: I run the DorkbotPDX order.)

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: April 15, 2011, 05:09:44 pm
content: Quote from: Laen on April 15, 2011, 04:25:42 pmI actually ordered 2 sets of boards (20 pieces) so 10 of the lot have been tested. Three have scratches around the TQFP, with the one shown being the worst.For my purpose of using these boards as handouts at a PCB design tutorial, I couldn't be happier - "Don't push the specifications if you don't have to" is a good message to get across.Making comparisons between board cost is definitely risky at best. Size matters. Quantity matters. Silkscreen on one or two layers matter. Routing, silk screen colors, hole sizes, etc, etc can all affect cost.Just for the record, I have no relationship with ITead Studios other than being a customer. I've ordered 3 lots of boards from them and been happy with the results, even though my first order got stuck in the China Post fiasco and took 3 months to arrive.

author: metalphreak
author_rank: Frequent Contributor
timestamp: April 18, 2011, 06:43:44 am
content: I had a similar idea to this, but I was planning on breaking out all the pins for various SMD footprints to pin headers as well. I'm always finding i'm using SMD parts and they're a pain in the arse to prototype with.