a new PCB manufacturing method wanted

[mstechca]

up until now, The only two ways I can make PCB's are as follows:

1. Draw the PCB with a black permanent marker and then etch it.

2. Wax the board, remove the wax on top of the copper to be removed, and then etch it.

Method #1 works only 1/2 the time because 1/2 the marker is rubbed off while etching.

Method #2 works well, but 1/2 the time wax pieces float in my etchant and it takes longer.

Because I already have CAD programs on my PC, I want to be able to print it out and slap the image on the board without using special "press-and-peel" paper.

Here's the problem. I don't have access to a photocopier, and I don't have access to a laser printer. All I have is an inkjet printer. One site claimed that the ink is not waterproof. Because I am able to refill my own cartridges, What kind of ink should I look for that works in an inkjet printer that is waterproof? (product numbers are good).

As for the paper, one website that I looked at mentioned that I can use glossy paper. Is glossy paper the only alternative to press-and-peel, or can I use other cheaper paper?

btw, I'm in Southern Ontario (canada, of course :wink: ).

Like I said, I want to make a PCB as fast as possible without spending a fortune, because buying a laser printer is the last thing I want to do.

 

[stevez]

Several of my friends use an "iron-on" method where they make a copy of the pattern - the toner or dark areas are to remain copper - the white will be etched away. An iron will fuse the toner sufficiently to have it adhere to the copper and will serve as a resist. I suspect you might have to touch it up. I am sure this process has it's limitations.

 

[Jay.slovak]

Several of my friends use an "iron-on" method where they make a copy of the pattern - the toner or dark areas are to remain copper - the white will be etched away. An iron will fuse the toner sufficiently to have it adhere to the copper and will serve as a resist. I suspect you might have to touch it up. I am sure this process has it's limitations.

But this only works with Laser printed paper, He has and wants to use Ink-jet printer!

 

[checkmate]

The obvious choice would be to use exposure methods. They are best with laserjets, but inkjet printouts with maybe a bit of pencil shading would do.

 

[evandude]

yes, it sounds like you need to use photoresist methods, or try to get a laser printer. In the end, a laser printer is usually more affordable. I paid under $50 for mine (which is cheaper than many inkjet printers, and since I use it for normal printing as well, it's not a cost devoted solely to PCB making), and the press-n-peel is about $1.50 a sheet. However, I pay only about 2 cents per square inch for blank PCB, because I don't need to use the presensitized board, which costs significantly more. and I can get several dozen boards out of one sheet of the press-n-peel (most of my boards are rather small) so even including the cost of both the PCB and the transfer film, it's still cheaper than buying presensitized boards... not to mention I only need an iron (which I always have for clothes anyway), not a flourescent or UV light, or any developing chemical, or transparency sheets. Heck, by the time you buy a couple of ink cartridges, you've probably already spent more than my printer, and I get thousands of pages on a single, cheap toner cartridge

Inkjet printers simply cannot be used with toner-transfer methods, no matter what kind of ink you put in them. the problem is the fact that the way you get toner onto a board is by melting it (toner is basically a very fine plastic-like powder, that is melted onto the surface of paper)... and inkjet ink is absorbed into the paper, (like any other ink) so it's nothing like toner, and as such, it will not work no matter what kind of paper you use.

 

[stevez]

You can take the ink jet original and copy it to get the fused toner "original" that you need. For some that's impossible - many others have easy access to a fused toner copier. It's one more step but might be worth the effort, especially if the alternatives are limited otherwise.

 

[Screech]

Whats wrong with Inkjets?

I use a 7 year old inkjet (Hewlett Packard Deskjet 670c).
I print on transparency, wich I get at the local computer swap meet.
Eagle's free software.
Uv sensititive copper boards.

Here's my first uv. board wich I made only a few days ago.
and my home made uv flouro light thingy.

 

[mstechca]

Stevez, so after you printed on the transparency, how did you get the board etched properly?

and what is the purpose of the UV light?

I don't want to start melting a transparency now.

 

[checkmate]

The "transparency" serves as a mask for UV exposure of the photoresist board. Masked areas are etch-resistant. Fluorescent can be used if UV is not readily available.

 

[evandude]

mstechca, it's a photo exposure method. It's similar to the film in cameras. There is no danger of melting transparencies because this is nothing like toner transfer... there is NO ironing.

you use boards pre-coated with a special resist that is sensitive to UV.

you print the pattern on transparency, then lay it on top of the board and expose the board by shining UV light on it (flourescent lights aren't idea but they work and are cheaper than real UV lights)

then you put the board in a developer solution (like you would use for developing photos) and the areas that were shaded by the printout will remain as resist, and the areas that were exposed to UV light will be removed... and then you have your resist patternfor etching.

the advantages are that it is the most accurate method for homemade PCB's, so you can get fine traces (although press-n-peel can come very close)

the disadvantages are as I stated before; the biggest is that you need to use the expensive presensitized boards. I pay approximately 2 cents per square inch for single-sided normal copper clad PCB material. So far, the best price I've found for the presensitized board is about 15 cents per square inch.
and you need to keep developer solution and a flourescent light around (not a big deal if you have space, but for us college students in cramped dorm rooms it can be)

I have wondered this though: can you cut just small pieces off of a presensitized board at a time, without ruining the rest of the board by bringing it out of its opaque plastic bag and exposing it to light? or do you have to use the whole board as soon as you open the package?

 

[Screech]

I have wondered this though: can you cut just small pieces off of a presensitized board at a time, without ruining the rest of the board by bringing it out of its opaque plastic bag and exposing it to light? or do you have to use the whole board as soon as you open the package?

You do not have to use the whole board.
Just cut off what you nead. The rest keeps well.
You should always cut off a little bit of every board, and test it for exposure time.

 

[mstechca]

is there any way I can use this method without buying the expensive photo-resist coated boards?

 

[samcheetah]

evandude, the boards have a protective covering that you have to peel off in a dark room before exposing it to light. so as long as that covering is intact you can cut the board to any size.

and transperency sheets arent that expensive at all. and developer solution is only a one time investment just like the etchant. you dont have to buy it again and again. it lasts quite a few boards. and one thing more. some boards can be exposed without a UV light source. you can use any 500W bulb.

but you are right about the space consumed. in your case press n peel is the best method.

 

[evandude]

well, quite simply, it's impossible to do it without photoresist-coated boards; it doesn't even make sense that it would be possible, since the entire idea of the process is exposing the photoresist. without photoresist, you're just shining a light on some copper :lol: The only two options you have are A) buy the pre-coated boards, or B) buy plain boards and photoresist separately and coat them yourself.

However, I believe you will find the photoresist liquid to be expensive enough to make the cost savings minimal. the photo exposure method may be the most accurate method for making PCB's at home, but it's certainly not the cheapest. like everything else in life, the better it is, the more it costs.

on the other hand, my first laser printer cost me $20; I bought it used from someone in the area who didn't need it anymore. It was 300 DPI, which wasn't incredible but good enough for most stuff. My current laser cost me $50, and is 600 DPI and does a great job. So when you break down the costs, toner transfer is often the most cost-effective solution that can achieve excellent results... especially over a long time period, where the costs of presensitized boards really starts to add up.

 

[stevez]

The fused toner copy is made on paper -not transparency. You put the toner side of the copy against the copper foil - and use a clothing iron on the non-toner side of the copy to fuse or melt the toner so it sticks to the board. The toner that is now stuck to the board becomes the resist so no need for any UV light.

I am not that familiar with this process however it would seem that narrow traces might be a bit beyond the capability of this process.

 

[evandude]

wow, this thread is getting messy. everyone's talking about different things and nobody seems to know what everyone else is talking about :lol:

yes, toner transfer is often done on paper, however it is much better when you use press-n-peel, which is transparency with an easily peelable blue coating on one side.

With photo paper toner transfer, I often had trouble with 12 mil traces, and stuck with 16 mil traces whenever possible. I also almost always had broken traces after transfer, which had to be repaired with a sharpie before etching.

With press-n-peel, I have NO PROBLEM achieving 10 mil traces, every single time, and have never had a single broken trace. The makers claim it will work for 5 mil traces. I don't doubt that it's possible.

With the photo exposure method, I know people can do 10 mil traces as well, and I'm sure smaller traces are also possible. this method seems to do a slightly better job keeping all the edges looking "crisp" when getting into intricate, small patterns.

however, let me say this:
when you start venturing below 10 mil traces, your etching process becomes very important, to minimize etching under the sides of the resist pattern which would quickly eat such a fine trace... and this is of course independent of the method with which you put the resist on the board. For hobbyist work, I can't see much reason to go below 10 mil traces except possibly in isolated areas where you absolutely have to cram TWO signals between a couple of IC pads instead of one :lol:

 

[i_build_stuff]

Can't you just buy regular boards, and apply the photo resist yourself?

 

[evandude]

As I said two posts ago, I don't know if you can buy it cheaply enough to make it worthwhile.

However, I did find ONE place to buy it that sells a bottle for $9 and claims it can coat 1700 sq. inches. Since it is applied with a spray nozzle, there would probably be a reasonable amount of waste, you probably wouldn't get nearly that much board space out of a bottle.

HOWEVER there is a big catch! the only liquid photo resist I've been able to find is NEGATIVE photo resist. this means you need to use a NEGATIVE of the pattern you want to transfer... in other words, the area you want to etch should be black, and the areas you dont want to etch should be left blank. That forces you to use SIGNIFICANTLY more printer ink to print out the patterns, and also might cause problems because an inkjet printer would probably have a hard time making large open areas of black be fully opaque.

the POSITIVE resist used on the presensitized boards is much easier to use because of that.

 

[mstechca]

mstechca, it's a photo exposure method. It's similar to the film in cameras. There is no danger of melting transparencies because this is nothing like toner transfer... there is NO ironing.

you use boards pre-coated with a special resist that is sensitive to UV.

you print the pattern on transparency, then lay it on top of the board and expose the board by shining UV light on it (flourescent lights aren't idea but they work and are cheaper than real UV lights)

then you put the board in a developer solution (like you would use for developing photos) and the areas that were shaded by the printout will remain as resist, and the areas that were exposed to UV light will be removed... and then you have your resist patternfor etching.

the advantages are that it is the most accurate method for homemade PCB's, so you can get fine traces (although press-n-peel can come very close)

the disadvantages are as I stated before; the biggest is that you need to use the expensive presensitized boards. I pay approximately 2 cents per square inch for single-sided normal copper clad PCB material. So far, the best price I've found for the presensitized board is about 15 cents per square inch.
and you need to keep developer solution and a flourescent light around

I guess I'll have to buy one of those boards.

 

[zachtheterrible]

hey mstecha, glad to see you finally realized that the wax method just isn't practical!

I just got a laser printer. Before that I'd print out the circuit on a regular piece of paper, and take that paper to a copy shop, and then copy my circuit onto staples photo paper, which works very well.

evan, I'll have to use some of this PnP blue that you keep bragging about :lol: