While not directly to do with Picaxe, I do use it to manufacture PCB's for use with Picaxe projects, so maybe someone else can benefit from my experience. I did a quick search and couldn't find this subject having been discussed before, so here goes...
For years, I've been using positive pre-sensitized PCB to make my own printed circuit boards. I retrofitted an old Canon scanner with a dual strip of UV Leds to act as the exposure device and it works very well. A few days ago, I realized I was running low on positive developer fluid, so I checked my places where I get supplies and got a shock. The last time I bought a litre of the stuff, about a year ago, it was $10.99 Cdn. Now, they want over $30!
I called my brother about it - as he's a chemist - and asked if he had any idea if he could bulk order it through his company to save a few $$. He asked me for the exact name of the product, which I gave him. A few seconds later, he replies, "Why don't you mix it yourself?" Huh?, was my response...
He tells me that all he did was Google the product name appended with MSDS and he quickly found the "Material Safety Data Sheet" for the product. Seems that it's required by law to make those available for hazardous chemicals. "So what's in this stuff?", I ask. He says, "10% Sodium Hydroxide (NaOH) by weight and distilled water, that's it"....
Because you mix the developer in a 1:10 ratio with water to get the working developing fluid (1 part developer to 10 parts water), the actual amount of NaOH in the working fluid is in a ratio of 1:100, so to make a litre of the final developing fluid to use for developing the exposed PCB, you just need to mix 10 grams of NaOH in a litre of water. He also suggested that I add the 10g to about 100 ml of water initially to speed up the dissolving of the NaOH. He told me it would get a bit warm, but nothing to worry about. Once dissolved, top it up to a full litre of water.
So, I just went to my local hardware store where I bout a 500g bottle of 100% NaOH (they sell it for unplugging drains and such) for less than $4. I got it home, mixed it up as described above (10g NaOH to 1 litre of tap water - I didn't have distilled on hand) and then put in my small test piece of exposed PCB scrap, and bingo, works EXACTLY the same as the $30 stuff!
So, for my ~$5 investment in NaOH, I can make 50 litres of final working developer. Buying the concentrate would cost me $150 (5 bottles on concentrate at $30/bottle to make the same 50L of final fluid).
I keep thinking how much money I've wasted over the years buying really expensive diluted drain cleaner.... Boy, do I feel stupid!
Live and learn
For years, I've been using positive pre-sensitized PCB to make my own printed circuit boards. I retrofitted an old Canon scanner with a dual strip of UV Leds to act as the exposure device and it works very well. A few days ago, I realized I was running low on positive developer fluid, so I checked my places where I get supplies and got a shock. The last time I bought a litre of the stuff, about a year ago, it was $10.99 Cdn. Now, they want over $30!
I called my brother about it - as he's a chemist - and asked if he had any idea if he could bulk order it through his company to save a few $$. He asked me for the exact name of the product, which I gave him. A few seconds later, he replies, "Why don't you mix it yourself?" Huh?, was my response...
He tells me that all he did was Google the product name appended with MSDS and he quickly found the "Material Safety Data Sheet" for the product. Seems that it's required by law to make those available for hazardous chemicals. "So what's in this stuff?", I ask. He says, "10% Sodium Hydroxide (NaOH) by weight and distilled water, that's it"....
Because you mix the developer in a 1:10 ratio with water to get the working developing fluid (1 part developer to 10 parts water), the actual amount of NaOH in the working fluid is in a ratio of 1:100, so to make a litre of the final developing fluid to use for developing the exposed PCB, you just need to mix 10 grams of NaOH in a litre of water. He also suggested that I add the 10g to about 100 ml of water initially to speed up the dissolving of the NaOH. He told me it would get a bit warm, but nothing to worry about. Once dissolved, top it up to a full litre of water.
So, I just went to my local hardware store where I bout a 500g bottle of 100% NaOH (they sell it for unplugging drains and such) for less than $4. I got it home, mixed it up as described above (10g NaOH to 1 litre of tap water - I didn't have distilled on hand) and then put in my small test piece of exposed PCB scrap, and bingo, works EXACTLY the same as the $30 stuff!
So, for my ~$5 investment in NaOH, I can make 50 litres of final working developer. Buying the concentrate would cost me $150 (5 bottles on concentrate at $30/bottle to make the same 50L of final fluid).
I keep thinking how much money I've wasted over the years buying really expensive diluted drain cleaner.... Boy, do I feel stupid!
Live and learn
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