board dimensions

[mabildgaard]

I have been working on two separate multilayer boards using Protel DXP. The boards are supposed to be 3.937" wide or 10 cm and they are supposed to be 31cm long or roughly 12.205". I have gone through and sent the gerber files to the fabrication house I use to examine them just so I can have someone tell me the dimensions. In the past, the boards I made have come out being smaller then specified. This was only by 80mil. I attributed this error to having included the keepout layer in the gerber files. (I had the keepout layer set 40 mils in from the outside edge.) The fabrication house used CAM350 to open the gerber files.

Can someone please give me some assistance and help me to fix the dimensions on the board. Any advice would be greatly appreciated.

Thanks,
Mark

[randychase]

Yeah don't send the keepout info in the fabrication gerber files. That adds some potential confusion, specially since in your case it looks like a board outline.

It is best to dimension the board on a fabrication or drill drawing layer and include that in the gerbers.

[cadpro2k]

Hi Mark,

No fabrication drawing with the gerbers tell the fab house what the board size IS TO BE? That's kind of curious. Don't you put it in notes somewhere in your data files? How long you been doing this?

I, for one, include a 'route' file with my gerbers that is simply the board outline (commonly referred to as a NC route file). I also include a fabrication drawing that specs such things as 1) fabricate per IPCxxx 2) a dimensioned drawing 3) HASL, silver immersion, gold plate, or whatever plating on the external surfaces 3) whether or not you want soldermask and what thickness... etc. etc. etc.

Nothing less. I'll call out things in the readme.txt file also if there are special instructions I wish to communicate to the board house.

Hope this helps.

Mitch

[mabildgaard]

Mitch,

I have maybe been laying out pcbs for a year or so. I work in a very small engineering group. Namely myself and three other guys. I had to go through and teach myself how to use Protel DXP and learn a hole series of things about it. Protel does not provide tons of info about industry standards. I am more or less left to my own to determine how things are done. I do not know everything. I do not claim to either. Its not like there is a manual that teaches you all of the wrong and right ways to do things. Yes, you can go through and ask questions on message boards such as this one. Doing this stuff is not the simplest thing in the world.

Mark

[cadpro2k]

awh, come on Mark. You can train a monkey to do this stuff. That's what my boss says anyways. HAHAHAHAHAHAHAHA

I know your pain. That's why listservers like these are so great in today's world. I didn't mean to be cynical responding that way to your question, so don't take it that way. Also, no question is a stupid question, so never be afraid to ask.

One thing you'll learn is, every designer has their own 'special' way of doing things, so there isn't ONE PARTICULAR 'right' way of doing something. We often complicate things though.

A couple recommendations I'll make to you. 1) get involved with an IPC Designers Council (www.ipc.org) chapter in your area if there is one and 2) visit a local fab house, if you can, and ask them how/what/why they'd like have data from you. It'll surely open your eyes.

Good day. Hope this helps you.

Mitch

[mabildgaard]

Thank you Mitch

[randychase]

Originally posted by cadpro2k

No fabrication drawing with the gerbers tell the fab house what the board size IS TO BE? That's kind of curious. Don't you put it in notes somewhere in your data files? How long you been doing this?


I have noticed this as a not uncommon practice. Back in the day, you always sent out a fab drawing. A manufacturer told me a lot of people don't anymore. Just send gerbers and they make the board to the board outline in the gerbers.