PCB Prototyping

[Rolf]

Safety first ..........

Thanks for your reply and link.

I have decided to get a laser printer seems as pretty much any method requires some form of toner printing. I could do with one for Uni anyway.

I'm considering making a vertical bubble etch tank like in the link - Just seems safer than an open tray.

I've just learnt how to use Eagle, how does Express PCB compare to that ?

Thanks.

No mater what type of etching fluid you use, you must have a backup, in case of spills. I use my tray in a deep utility sink so that any spill can be flushed down the drain quickly. The sink is made of plastic so no harm will cone to it. Seems like vertical etching tanks has to be constructed with a broad base to prevent any chance of it being knocked over. I would also be suspicious of the fumes generated by the bubbles bursting into the air.
I also keep a box of baking soda close by. I newer use more etching fluid than is needed, this is not possible with a etching tank, so if you have a knock over spill it will be many times larger than with a tray.

I had at one time a friend that bought and installed a commercial etcher in his workshop, within a few months all his tools looked like they had been dug out of some prehistoric cave.

I used Eagel brifely before switching to Express PCB.

 

[yngndrw]

Ah, thanks. So baking soda nutralises the acid ? I never new that, you learn something new every day.

I'll also look into Express PCB.

One question about your sink - Wouldn't the acid eat into any metal drain pipes ? That is if it spilt, there's going to be some acid that goes down the drain before you get a chance to pour water down after it no ?

 

[3v0]

Thanks I'll get some Sodium Phosphate, in my local supplier (Maplin) it seems to be cheaper that Ferric Chloride aswell.

Opps.... I should have said Sodium Persulphate not Sodium Phospate. Maybe you will have better luck finding the right stuff. The product I use in made by MG chemicals.

Using a zip-lock bag, I dunno it seems dodgy to me - What if it doesn't seal properly ?

Use Zip Lock Freezer bags. They are sturdier then regular zip locks. I would do the etching over, or in, a sink in case of a leak. Would not do this with any etchant other then Sodium Persulphate. It is very tame compared to the acids or Feric Chloride. I try to avoid getting it on my hands but do not wear gloves. Just wash them when done. Do not take my word for it, check the material data safety sheet.

I etch with Sodium Persulphate in a glass cake pan. I heat the water in the microwave then put the solution in a pan under a halogen work light to keep it hot during etching. I use just enough water to cover the board. The used up etchant goes into a butter tub and the water evaporates leaving blue crytals.

 

[Rolf]

Ah, thanks. So baking soda nutralises the acid ? I never new that, you learn something new every day.

I'll also look into Express PCB.

One question about your sink - Wouldn't the acid eat into any metal drain pipes ? That is if it spilt, there's going to be some acid that goes down the drain before you get a chance to pour water down after it no ?

I am lucky there are no metal pipes or fittings on the drain of this sink. Even the sewer pipe is PVC.

 

[yngndrw]

Opps.... I should have said Sodium Persulphate not Sodium Phospate. Maybe you will have better luck finding the right stuff. The product I use in made by MG chemicals.

Use Zip Lock Freezer bags. They are sturdier then regular zip locks. I would do the etching over, or in, a sink in case of a leak. Would not do this with any etchant other then Sodium Persulphate. It is very tame compared to the acids or Feric Chloride. I try to avoid getting it on my hands but do not wear gloves. Just wash them when done. Do not take my word for it, check the material data safety sheet.

I etch with Sodium Persulphate in a glass cake pan. I heat the water in the microwave then put the solution in a pan under a halogen work light to keep it hot during etching. I use just enough water to cover the board. The used up etchant goes into a butter tub and the water evaporates leaving blue crytals.

Just to check, is this the right stuff: **broken link removed** ?

Do you have to make the full 0.5l of fluid or can you store the un-used crystals in a re-sealable bag ?

I am lucky there are no metal pipes or fittings on the drain of this sink. Even the sewer pipe is PVC.

Ah I see, I might build a plastic sink which drains into a plastic container, which can then be weakened with water before flushing in case of spillage.

 

[picbits]

If anyone is interested I can get 25kg bags of Sodiup Persulfate for a very very reasonable price and can split for the UK PCB makers ..........

 

[yngndrw]

I guess you're looking at around £20 per kg ?

 

[picbits]

If my calculations (and memory) are correct I can sell this back on at £5-£6 plus postage per kg and still make a small profit to cover the stuff I use myself.

I tried ringing my contact earlier at the place that can get it for me - they use tons of chemicals every week so get bulk rate pricing on all chemicals they purchase. Unfortunately my contact is on holiday at the moment but I can get some firm prices next week for anyone interested.

 

[3v0]

Just to check, is this the right stuff: **broken link removed** ?

Do you have to make the full 0.5l of fluid or can you store the un-used crystals in a re-sealable bag ?

It looks like it is similar. You do not have to make it all up at once. I use 1 to 3 tablespoons of crystals each time I make up the solution with just enough water to cover the bottom of a glass bread loaf pan. It etches a few small boards prior to being used up. With a bit more heat and some extra time you may get another board out of it.

The stuff I use is $20.75 for 1Kg. I do not see a distributor for MG Chemicals in the UK. You should be able to find it in France if that helps. These should be others who supply it.

 

[yngndrw]

Ah brillient thanks guys, looks like Picbits could be my supplier at that price.

Bit strapped for cash ATM though. ;o

 

[picbits]

Ah brillient thanks guys, looks like Picbits could be my supplier at that price.

Bit strapped for cash ATM though. ;o

You can call me Dom

On a serious note though when I get proper pricing through I'll bung the stuff on my website and you can order and pay with Paypal/Credit card etc.

I know they also have Sodium Peroxide that they buy in at 4 tons at a time but I think they only get it in liquid form.