PC board questions

[phil b]

I would like try the press-n-peel transfer film to make PC boards for my RE projects. Has anyone had experience with it?

Also, what PC boards do you folks prefer to use?

And finally, where can I get software, preferably free, to design PC boards?

Thanks,

       phil b

[RatOmeter]

For free PCB software, you might go to http://www.expresspcb.com/

They offer free software to induce you to use their PCB manufacturing services.  I've never used them, but quotes I've gotten from them seem competitive.

I've used the dry transfer stuff from Radio and had to deal with it flaking off.  I've used the press and peel stuff that you print out with a laser printer on special transfer sheet, then iron on.  That stuff works pretty well, but you need to follow the instructions very carefully.  I've had trouble with getting it too hot and also peeling it off too soon.

With both types, you can fix small errors in transfer using a "resist ink pen" (basically a standard indelible ink marker with a fine tip will do).  For gross errors, you're better off cleaning up the copper and starting over.

As for blank PCB material, the stuff that's readily avaible at Radio Shack or hobby electronics retailer should all be OK.  Your only real decision would be single or double sided (I'd start with single sided boards if you've never done it before.

It should go without saying, but be careful using, handling and storing the Ferric Chloride echant.

[baggo]

Hi Phil,

another freebe which I have been using is available at http://www.pcb123.com. Again this is to encourage you to use their board manufacturing facilities. I find it most useful for drawing up schematics but have used it to produce boards. They all seem fiddly to use as quite often you have to design your own symbols and footpints. The idea is that you first draw the schematic and then convert that to a board layout via a 'rats nest' This is literally what it suggests - a mess of tracks and components which needs to be sorted out into a working layout. This bit I find very tedious and usually finish up doing most of it manually. I then print out a transparency of the pcb on OHP film with an inkjet and use that to expose photo-sensitive copper clad board in a homemade UV exposure box. The board is then developed with a suitable developer and etched in the normal way. It is possible to produce very professional results this way and is great if you want more than one board the same.

I used to use the rub down transfers to make similar transparencies but as Ratometer suggests they sometimes don't stick very well, especially if a bit old. If you want to use them straight on the copper clad board then the copper must be spotlessly clean.

When etching the boards I hang them vertically in a suitable container of etchant which stands in hot water to raise the temperature. I also aerate the etchant with an aquarium air pump and air stone to keep the etchant on the move. The container needs to be covered though otherwise you end up with a fine spray of etchant everywhere! Both heating and agitating the etchant speeds up the etching process greatly.

Hope this helps,

John

[RatOmeter]

Thanks for bringing up the photosentive PCBs... I'd forgotten that option (probably because I've never used it myself).  My guess is that is probably the best option for high quality homemade PCBs.

One idea I've got for someone who wants to make a UV exposure box is to acquire an old blueprint machine (I have two) and use its UV lamp and ballast.  Blueprint/blueline machines have been pretty much obsoleted by computers and plotters;  so much so that companies that still have them are resorting to giving them away or trashing them (that's how I got mine).

They might be hard to find, though, since everyone who's got'm know they're virtually worthless.

[commanda]

I use AutoTrax. Runs on dos. Free download. Any pcb maker can use the files. Updated video drivers are available.

Print it to the shiny side of the backing paper on Avery laser printer labels with a good laser printer. Contact print it to really clean copper using a heated laminator. One with adjustable temperature & speed. I've made hundreds (almost) of boards this way.

Amanda

[RobD]

I do a lot of PCB work and have tried several systems.

A really good pcb program is Eagle by Cadsoft. If you do small boards (under 3"x4") you can use their program free as long as you don't use it commercially. It even has a top notch auto router.

The best system for making a pcb boards is the photo sensitive one and the best place to buy boards is from Circuit Specialists. They have tanks and ferric solution also. The best way to make a layout for the photo boards is with clear overhead projection film that you get at Staples or any good office supply.

If you follow this system you can make excellent boards very cheaply. I've tried the iron ons and they don't work well at all. Don't waste your time.

RobD

[nack]

You can use laser printer toner and iron it on - if you have access to a laser printer.  Best results are reported with Staples house brand photo-inkjet paper, but any glossy coated photo ink-jet type paper should work.  Print with the darkest possible setting to get lots of toner on the paper.  Clean the copper clad board by wet sanding with 400 paper under running water - you can use a little bar soap to lube the paper, but make sure it all rinses off.  Once board is clean, do not touch artwork area.  Place the board copper side up, place the paper artwork down on the board center it up nicely.  Next you'll take your clothes iron (on it's highest setting) and iron the paper onto the board for about 2 minutes, try keeping the iron totally still with lots of pressure on it for the first 30 sec or so to get the paper tacked down, then move the iron to the next unheated space and repeat until the whole art-work are has been ironed, then, with less pressure and making sure the iron stays flat and does not dig in to the paper, move the iron around to make sure that all the board all the pattern is well transferred.  Then you let it cool for a couple minutes and proceed to soaking off the paper - this is where the glossy coating really helps.  Liquid dish soap as a surfactant will help loosen the paper.  When the paper is soaked well enough to fall off the board, you can inspect the artwork - you may have to repair a few traces with a pen, or you might have to scrape the paper coating crud off of some areas.  The board is now ready to etch.  Try Circuit Specialists for pcb supplies and cheap etching tanks.

[(unknown)]

Try this link   http://homepage.ntlworld.com/seanellis/avrrobot_hw.htm which explains how to make the Eagle software make stripboard layouts.

Now you don't have to worry about making your own PCBs