Laser printer for PCB question

I've not tried the acetone method but I'am sure the right paper makes all the differance.I'am going to try it with my paper and will let you know what happens

BB

Well I tried the acetone with my paper,which does have a clay coating and it didn't take long to see a mess.My suggestion would be get out the iron until you can get the acetone figured out.It would be great if we could get it working right.I'll keep trying and will let you know of any success.

BB

I'd happily get out he iron if I thought there was any hope of getting registration on a double sided board 280mm long!

Git

well after trying all weekend to use acetone I give up.I must not possess the magic that you need to get this done.sorry Git hope you have another plan.

BB

I've drawn the same conclusion. My UV tubes are on order and I'm going back to good old photo methods.

I wonder if Whacko has wound us up?.....


Git

seeing how its just you & me trying this i would say he fried a couple of fish .What can i tell ya but the guy does call himself Whacko

bb

Git: use only fumes from acetone or toluene . It works excelent for toner.
I use time 10-20min. and everythink is OK.

pool_77

How do you manage the conflicting requirements of keeping the artwork in contact with the PCB and allowing the fumes access to the toner?.

Git

yes please go into a little more detail of your process.it sure makes more sense than what we've tried already.

BB

see enclosured picture, please.

pool_77

there's no heat or light involved? just tape your artwork to the copper and glass and let it fume for 20 min?.and which chemical do you think work's best for(and paper)

BB

Pool - should have thought about it before I replied - there are obvious ways of holding it, as you show. To echo barney, I would like to know some more technical data of the process such as paper type etc.

I was about to build a new UV light box but now I am torn again - should I try acetone again?. . .

As an aside, I've struggled using Laser printed artwork for UV exposure in the past - very hard to get good density and free of patches. Today I tried an Inkjet for the first time set on 1440dpi and the results are superb - totally opaque. I assume everybody else knew this

Git

it is only for getting gark of artwork, then is used common photoway with resist (positive 20 spray).
I am using 12 mil tracks without problem.

pool_77

Ah.. we've misunderstood then. As I said above, if you want dark artwork try an inkjet, the results are many times better than laser.

Git

Follow up :

These are the best results I've ever had. I exposed a sample board precoated from Mega, supplied as Fotoboard 2, and developed it with half strength Seno universal developer (25 grams to 1 litre).

I tried to get annular holes with GCPrevue and was interested to see if they would develop as I've had trouble in the past. The 0.5mm holes in each pad had an internal crosshair made by GCPrevue which I couldn't find out how to turn off. Not only were the holes retained but the crosshairs are perfectly exposed too. I would estimate they are made of lines no more than one tenth of the hole diameter, so 50um (2 thou) at most.

I've changed two things at once by using Seno developer instead of NaOH, and artwork produced by Inkjet rather than Laser, but I'll never go back to Laser after seeing these results, they are fantastic. Pity I can't etch it right now.

Git (feeling very happy)

If the artwork turned out good the etch job should be just as good.glad your back on track.when doing boards that big the best approach is usally the most expensive but the results usally make you forget the extra cost.anyway's keep us posted on how it all turn's out.

BB

Etched the boards today and they turned out first class except for d@mn3d FeCl staining of the surface. I don't think many of the crosshairs survived as copper but that's not too surprising!. The resolution looks excellent and I'm fairly confident that 0.15mm tracks would have been ok.

I'm going to try the immersion Tin plating solution tomorrow for the first time. Does anybody have any experience of that, good or bad?. Should I drill the board before or after plating?

Git

Hi

I've been trying out the blue Press-n-Peel transfer method at least 20 separate attempts all with very disappointing results. There's always ripped tracks or holes here and there. Before I give up on it completely, can anyone suggest what I am doing wrong?

The first sheet I printed was on a big office HP 4500 series colour laserjet set to densest black. I also tried my own HP 1022 laserjet which claims to have a true 1200 dpi resolution.

As for the boards, I tried cleaning the copper with just steel wool and later with steel wool and then dipping them in ferric chloride for a few seconds. The first 6 attempts at pressing I used a heat press at a range of temps and times eg 200 - 300F, 1 1/2min to 3 mins etc. Later I tried 6 or 7 times using a clothes iron on a range of temp settings. All miserable failures. I haven't managed one perfect board yet.

Should I forget it and try UV?

Thanks

Trevor

Here are some guide lines tha t a friend of mine wrote fo me who has been using teh press n peeel method for years and he swears by it get excellent results every time

Press-N-Peel - wonderful stuff!!! There is a small learning curve but if you pay attention to detail it works fantastic. I haven't had a bad board in years using the stuff. You didn't say whether you were using the Press-N-Peel Wet or Press-N-Peel Blue. I prefer the Blue since it doesn't require any soaking in cold water when finished and it has an extra thickness of the blue film which is very helpful with small traces. From an application standpoint, the only difference between the two types is how you remove it from the board when finished.

Here are the procedures that I go through with every board.
1- Cut the board to a size about 1/2" larger than the circuit requires.
2. After cutting the board, take a file to the edges and file down the copper edge of the board at about a 45 degree angle all the way around. No matter how the board was cut - with a shear, saw, or whatever, the cut leave a little edge standing up and this is enough to hold the iron up off of the Press-N-Peel in spots.
3. Take a piece of real fine sand paper and rough up the surface of the pc board. You are not looking at removing any copper, just enough scratching of the surface to give it a little 'tooth' for the plastic to bite on.
4. Use a clean soft rag with a little rubbing alcohol on it and clean the board surface, removing any copper dust from the sanding as well as finger prints. Don't touch the surface again after this.
5. Turn your iron on at a setting around the Rayon point (don't know how your clothes irons are marked over there). Do not use any steam. The iron should also be the type that doesn't automatically shut off when the temperature setting is reached.
6. Place the pc board on a paper towel, copper side up. Before I lay the Press-N-Peel down on the board, I usually take a soft paint brush that I keep just for this purpose, and brush off any lint, dust, etc that may have settled on it. I do the same thing to the P-N-P.
7. Lay the P-N-P centered on the pc board, printed side toward the board.
I know some of this is obvious but I'll include it anyway 8. Place the iron on top of the P-N-P and let it set for 10 - 15 seconds.
Then, not pressing down but letting just the weight of the iron do all of the work, I move the iron over the top of the P-N-P in small circles. The point to this is you are not ironing the P-N-P to the board, like ironing a shirt, but you are heating up the pc board to the same temp as the iron to allow the plastic in the toner and the film from the P-N-P to adhere to the board. If you want, you can place a clean sheet of paper between the iron and the P-N-P as this will help reduce some of the drag from the P-N-P as it heats.
9. The length of time that I apply heat generally depends on the size of the board. It can be anywhere from 2 to 5 minutes. Longer is better from my perspective. As long as you don't have the iron too hot, nothing is going to happen by leaving the heat on "too long".
10. After removing the iron, you have two choices. You can let the board sit until it is cool enough to touch and just slowly remove the P-N-P, or, you can pick the board up by the corners of the paper towel and carry it to the sink and run it under cold water. In this case, the cold water is helping to seize the plastic to the board faster and has nothing to do with actually removing the P-N-P if you are using the P-N-P Blue.

I then inspect the board for any places that the P-N-P didn't adhere to and I just a magic marker (permanent ink marker) to fill in those spots. If you leave the board in the etchant too long, it will eventually eat through the ink before it does the P-N-P but I've found that usually the copper is removed from the board long before it starts to penetrate the ink. Believe it or not, red ink has a thicker base coat that the black does so I try and keep a red marker around for that purpose but the black ink does work.

I don't remove the P-N-P until after I have drilled the board. To remove it, you can use a fine grade steel wool but it takes a lot of rubbing to get everything off the board. The first time you go to remove it, you really realize how well protected your traces are from the etchant. What I have found easiest is take just a small amount of paint thinner on a paper towel and rub it lightly over the P-N-P. I let it set for about a minute for the thinner to penetrate the P-N-P and then using the same paper towel I just rub around the board until everything is removed. The paint thinner does not hurt the pc board. When finished, I use a little soap and hot water to remove any residue, put the pc board in my shear and trim it to size.


I have not tried it yet but i found out where i was going wrong when i tried so now i'm fairly confident that i will crack it

wizpic

for cleaning the resist I've Acetone to work the best,if you can't find Acetone just use nail polish remover(mostly acetone)