some pcb solder/paste layer questions - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2011, 11:47:32 am
content: Hi, I'm trying to get some small pcbs made to use as ID style dogtags for a computer gaming event. (28mm x 50mm)They won't have any components on them, just text for the event name and stuff plus one drill hole for the neck strap thing.I'm going to get the boards done with black soldermask and electroless nickle/gold immersion because I want gold text on black background.If anyone can help me with the following questions i have, that would be great...What pcb layer do I want to put the text on so it gets gold plated?If I understand the layer names correctly then text on the "Top Solder" layer should come back gold plated, is that correct?There is also a "Top Paste" layer. Most surface mount pads seem to exist on both solder and paste layers. Do I need to have two copies of my text one for each layer (solder and paste) or just on the solder layer?I suspect the “Top Paste” layer is only used for making the SMT stencil and not the pcb itself, so can be ignored when just getting a pcb made. Is that correct?Also, does anyone know if the pcbcart.com online quote system calculates gold immersion correctly. It seems really cheap, only 2.7% more per board, $1.81/board vs $1.76/board for just hot air levelling.Any other recommendations or comments about common mistakes are welcome. Since i'm using pcb's for something other than making circuits I want to make sure I get this right before I send the gerbers/ncdrill away.I'm using altium designer to make the pcb

author: VIPR
author_rank: Contributor
timestamp: March 07, 2011, 12:17:03 pm
content: You will want to put the text on either the "top layer" or "bottom layer" as well as the respective solder layer. The top and bottom layer are the actual copper, while the solder layer(s) represent where you want the copper exposed so that the copper will not be covered by the black solder mask.You won't have to worry about the paste layer since that is for use with a solder stencil.I have used PCBcart for a long time and 99% of the time whatever the price quoted on the online system is the price you will pay. The only time this has not been the case for me was when I ordered a PCB that was over sized and was difficult for them to produce.

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2011, 12:20:49 pm
content: thank you for that, that's the exact information i wanted.

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: March 07, 2011, 02:10:19 pm
content: Using Eagle terminology, you have to put the text in the TOP layer, which is the copper but also put it in the tSTOP layer to prevent it from being covered in soldermask.Traces are normally covered in soldermask, so you have to add to the tSTOP layer to prevent covering it.You'll also need to put the board outline in the DIMENSION layer which will end up in the silk screen layer when you use the CAM processor so they know how to route the board.Jon

author: Zad
author_rank: Super Contributor
timestamp: March 07, 2011, 05:00:32 pm
content: That has reminded me, has anyone ever seen PCB business cards? It seems to me that setup costs would be quite low owing to the small area, with few holes etc. It would be something distinctive to give out, especially with selective use of gold plating which would cost a fortune on conventional cards. The only ones I have seen on Google are experiments at populated ones, with USB connections that paranoid corporates won't dare plug in anyway. Evil Mad Scientists have one, which is an Atmel breakout board, but it looks loke a PCB that just happens to be something that is business card sized.

author: VIPR
author_rank: Contributor
timestamp: March 07, 2011, 06:24:41 pm
content: Quote from: Zad on March 07, 2011, 05:00:32 pmThat's not a bad idea. I have never seen it done before but it makes perfect sense to do so. PCBcart.com offers FR4 thickness down to 0.4mm (.016") which would be about 1.5 times the thickness of a standard business card. If you bought a bunch of them the price would probably be very reasonable.Black solder mask with gold plating would look pretty sexy as a business card!

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2011, 10:34:59 pm
content: I've got another question, what's the best way to say i want them to route rounded corners on my pcb?Since i'm sending them the gerbers for a single board and not a panel of boards i'm not sure if putting lines/arcs in the fabnotes layer with a note saying "routing" is the correct way to do it.Any ideas?I'll probably tell them i want rounded corners in the website notes section when i submit the order but i just want to check what the correct way to show routing is when they will be the ones paneling it.

author: osmosis321
author_rank: Regular Contributor
timestamp: March 07, 2011, 10:48:01 pm
content: Your Gerber files will need to include a layer representing the board outline. That's where you specify the board shape, and any other particulars that come to mind, ie silkscreen layer colors, board thickness, copper weight. All these and more can be placed as text onto this layer.

author: VIPR
author_rank: Contributor
timestamp: March 07, 2011, 11:08:35 pm
content: Quote from: Psi on March 07, 2011, 10:34:59 pmThat is all part of the gerber file that represents the mechanical layer. In A!tium, your first mechanical layer should most likely be called "Mechanical 1" in one of the tabs at the bottom of the design workspace and by default should be colored pink. Just choose that tab and draw your rounded corners using arcs and straight lines to make the sides. Then select all on that layer and go to Design-->Board Shape-->Define from Selected Objects. Then the board will appear on the screen contained within the new shape that you just made. Hopefully that makes sense.The board house will have no way to make a rounded corner except by routing.

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2011, 11:26:03 pm
content: thanks, that worked well. Now i have a board with rounded corners

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2011, 11:33:22 pm
content: One last question, on the pcbcart website when getting a quote there is a compulsory field called "Part Number"Any idea what to put there? Is it just a free field for me to make up my own part number for my board?

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: March 07, 2011, 11:43:21 pm
content: It's you part number and can be anything you like, such as IDTAG or IDTAG2011 if you may have different versions in the future.

author: VIPR
author_rank: Contributor
timestamp: March 08, 2011, 12:06:49 am
content: Yep, as Jon said, any arbitrary name/number will work. It's really only for your reference an for re-ordering the part later if need be.