Quick Etching Question???

[WLS]

Hi Everyone,

After developing positive based board with the UV light and before it is actually etched with the acid.

Is the board still light sensitive?

Reason being that I do my development of PCB inside and the actual etching out side in my unheated garage. Being for health reasons I can not always work in a un-controled space. "Weather Permitting"

Is it possible to develop the board and by keeping it clean and scratch free. Then perform the etching at a later date?

If so, should I place it back into the black plastic bag?

Or should I just wait and do the whole process at the same time?

Thanks,

Bill

[sean k]

Once the board has been developed ie, had fixative added as the UV light is the developing, then the board is ready but like normal photographs or light sensitive materials they can degrade over time given the type of enviroment they are exposed to. But the problem you may have, if the time stored is large,is not that the film would degrade but that the copper surface would oxidise so instead of storing in a black bag it might be better to vacuum pack it, zip lock bag and suck all the air out with your mouth when its almost closed, or rub some sort of  easily removable oil or wax over your etchant ready boards.

But if it's only a week or two then you should be fine. But I may be wrong! 

[WLS]

... is not that the film would degrade but that the copper surface would oxidise so instead of storing in a black bag it might be better to vacuum pack it, zip lock ...

But wouldn't whatever copper does oxide and degrade be removed in the etching process.

Am I wrong, but leaving it in the black bag and primarily blocking light would assist in preserving the photographic materls.


The board that I am using the manufacture MG says you can leave the photographic material on the board and solder through it.

No need to tin!

Bill

[Ice-9]

Thats correct, you can leave the photoresist on the board and solder throught it. It also helps protect the copper tracks from future oxidation (just like a soldermask)
If you want to get really into it, you can expose your boards then etch them then epose them again to another clear print which only shows the pads, after that you can develop the board again and this leaves all the solder points clean. (don't etch again though)

[WLS]

...

If you want to get really into it, you can expose your boards then etch them then epose them again to another clear print which only shows the pads, after that you can develop the board again and this leaves all the solder points clean. (don't etch again though)

So, what you're saying and not that I'm that into it but, for clarity.

The secound template would be the same as the first except the pads would be eliminated.

And of course not to repeat the etching process again, or your pads will be permanently missing.

Sounds like it  would be to risky on a board with fine traces. You would have to align your template up perfectly to get it to work.

Thanks for the thought though.

Bill

[Ice-9]

Yeah , the second template would effectively blacked out apart from the pads. Ive ssen it done and itworks great although you do have to make a good job of aligning the second template to the pcb. Personally i dont bother as the heat of the iron clears the photoresist off no problem. I am just etching a pcb now so can post a pic of it as soon as its done.

Getting back to your original question. I just use 2 of those little food containers with lids from asda at 49p each. one for the developer and one for the ferric. I put 125ml of developer and etchant in each. To make the ferric work quick i also put the container in a small bowl with hot water in it to keep the temp up. Now with the id on the food container with the etchant in i can leave it outside in the bowl of hot water even if its raining.

[Ice-9]

Here is the pic of the pcb ive just done . it took 30min from start to finish. (not drilled yet). The finished chemicals end up in on old engine oil plastic bottle to be disposed of properly. What i'm getting at is once you get used to doing something in a certain way that suits you its as easy as safe and as quick as making breakfast in the morning.

You could even make as much etchant to go in a zip lock bag to do 1 small board, I hope some of what i'm saying make sense as i tend to babble on a bit.

[WLS]

Ice-9 Nice Board!

I just started etching and yesterday I developed a few test pieces before developing the board I'm going to use for my Deluxe Electric Mistress.

I like the freedom attatched to being able to develop your own board. For a template I started with GGG's template but replaced the 18 volt transformer with a TC-1044 charge pump. I left a way to go back to the 18 volt transformer if I have to by adding a couple of extra pads. I also added a pad for a resistor to the clock trim pot that I  will be making external. Suppose to open up the pedal to an array of sounds. The resistor is their to adjust the pot cause I read that when the clock is turned too much the noise comes through.

Anyways back to etching  I am using a 65 watt black light that sits about 10 inches above the work piece. I left the clear sheld on the fixture to cut the intensity of the light. I was told slower is better "more control". I get a real nice image with 20 minutes under the light and the developer acts quickly at this time leaving more than a sufficient amount of photoresist on the board.

I have to store the board till the weather breaks, but I made the wife fill up her widow wash so that I can have the container to store my acid.

Bill

[Ice-9]

Yeah it's good to design and make your own boards, and as you say you can have a design that incorporates multiple option for components.

Once you have you board developed store it in a cool dry dark place. The polythene bag that the pcb comes in is fine for this as its light proof. You should be able to store it for quite a long time. there may be more info on the manufacturers web site. One thing to bear in mind is that the fibre photoresist board does have a shelf life from manufacturer.