No reason I can think of. picnic coolers are cheap, and have a good lid. I built
my tanks because I needed those dimensions. I coudnl't find anything off the
shelf that was narrow and deep enough, base = 45x250mm high = 350 mm.
Any of the food plastics are ok with strong acids.
Now you only concern is getting hold of some lab equipment.
Here is lab order list.
1 ∗ 5 ml class B volumetric pipette
(preferred to graduated pipette)
(buy a second in case you break it)
1 ∗ rubber bulb pipette sucker
1 ∗ 125 ml dropper bottle for indicator (makes life easier)
1 ∗ 50 ml glass burette, class B.
1 ∗ 0-50°C (or 0-100°C) glass thermometer
1 ∗ 250 ml erlenmeyer flask
1 ∗ Bromophenol Blue indicator
(1 gram will last you ever and a day)
You also have to make some kind of stand to hold the burette, I made something
out of wood that was a ∗LOT∗ cheaper than buying a dedicated stand. Fasten the
burette with rubber bands to a length of wood, and hold that by a stand from a
heavy base using a diagonal pole. The area under the burette nozzle needs to be
free to place the erlenmeyer flask.
The deionized water and sodium hydroxide is available from most supermarkets.
You also need some ethanol to make up the bromophenol blue indicator. Its
probably better to get the right indicator rather trying to use turmeric power
because it will be easier to see the end point of the titration, which makes the
job easier to carry out.
grantfair2001 wrote:
> --- In Homebrew_PCBs@yahoogroups.com, adam Seychell
> <adam_seychell@y...> wrote:
>
> Thanks Adam - this is helpful advice. Is there any reason not to use a
> plastic picnic cooler? I believe these are PVC.
>
> Grant
>
>
>>I agree, ferric is the good old "standard" hobby etchant. Its quick
>
> and low fuss
>
>>to getting started. Simply pour some into and old ice-cream
>
> container, place in
>
>>the board and agitate or let it sit.
>>The cupric chloride etchant will require a special etching tank
>
> permanently
>
>>setup. However if you do a fair bit of prototyping I definitely
>
> think its worth
>
>>the effort building one of these tanks or buying one. Its clean
>
> because the
>
>>etchant stays in the tank, and there is no setup time involved, just
>
> flick the
>
>>aquarium pump switch and insert the PCB. I found you also need to
>
> make something
>
>>to hold the PCB while its immersed in the tank. That way not a drop
>
> should spill
>
>>on the floor or your skin. Unfortunately chemical resistant tank
>
> building is not
>
>>that easy. There are a number of ways it can be done, but the best
>
> is probably
>
>>from perspex sheet and various plastic building materials. Glass is
>
> not a good
>
>>idea as I found that silicon sealant doesn't make a good long term
>
> seal for acid
>
>>solutions. The silicon goes a little softer than usual and after
>
> several months
>
>>to a year it eventually gets salt creep between the glass silicon
>
> interface.
>
>>Once that happens its a run away effect and you will loose the tank
>
> contents.
>
>>The easiest way to to find a plastic fabricator and ask them to make
>
> you a very
>
>>basic slit tank from 3 mm PVC. The top of the tank should be flanged
>
> outwards
>
>>for added strength, and also to act as carry handles. They will be
>
> able to make
>
>>this kind of thing in 15 minutes. My tank cost AUD$40. PVC is a good
>
> choice
>
>>because its easy to work with and can glued for modifications. Note
>
> that PVC has
>
>>a 48°C temperature rating, after that is starts to weaken. The good
>
> thing is
>
>>cupric chloride works so fast you can keep it at room temp.
>>
>>The $175 quoted for 1lb of cupric chloride must be an analytical
>
> grade from a
>
>>lab supplier. For etching you don't need such purity. Read my post
>
> "Subject:
>
>>Preparation of cupric chloride etchant" from the other day. Its
>
> possible to
>
>>prepare the etchant from water, HCl and scrap copper metal, all of
>
> wich are very
>
>>cheap and readily available.
>>
>>Acquiring the titration equipment is probably be biggest headache
>
> for the
>
>>hobbyist0. However once you own this equipment there is no
>
> maintenance costs.
>
>>Its very basic lab equipment so any lab supplier will sell this kind
>
> of stuff.
>
>>There should be plenty places around, just look in the local
>
> business directory.
>
>>Lab suppliers have a tendency not to sell chemicals cheap. Thats ok
>
> because you
>
>>only need to get the glassware from them (indicator powder if price
>
> is right),
>
>>and the chemicals come from supermarkets. You could probably get
>
> away with food
>
>>dyes for the indicator, even turmeric powder is probably accurate
>
> enough. The
>
>>NaOH standard solution can be made up if you know anyone who has
>
> 0.01g accurate
>
>>scales. An far easier way to prepare standard NaOH will be to make up a
>>saturated solution, measure its temperature and then look up
>
> solubility chart to
>
>>find the concentration. For example, the solubility of NaOH at 20°C
>
> is 1090 g/L.
>
>>Pipette 5.0 ml of saturate into exactly 1 liter of deionized water
>
> to get
>
>>0.005∗1090/40 = 0.136 Molar standard NaOH solution. You have to buy
>
> a pipette
>
>>and pipette sucker for doing titration anyhow.
>>
>>The fumes from cupric chloride ethants are minor as the HCl
>
> concentration is
>
>>approx 1 Moles/L or 3.6%. It smells a little at room temperature,
>
> but only if
>
>>you put your nose up close while air is bubbling through the
>
> solution. Just keep
>
>>the windows in the room open and everything will be fine. Iron tools
>
> have a
>
>>tendency to rust around HCl fumes.
>>
>>Adam
>>
>>
>>grantfair2001 wrote:
>>
>>>I think there are many reasons that ferric chloride is still used so
>>>commonly. It's the "done thing". If you just ask around most advice
>>>about making PCB's will be to use FeCl. And it is readily available,
>>>as are the persulfates which can also be used to etch.
>>>
>>>The CuCl approach has several advantages - it is cheap, after the
>>>initial investment for equipment (and maybe chemicals - the mail order
>>>source I found in Canada for CuCL wants $175 for a pound!) and cupric
>>>chloride is very environmentally friendly, since you don't have to
>>>throw out the solution, just top up the hcl from time to time. But for
>>>this you need some lab equipment to do titration, and some bromalin
>>>orange indicator. All this is new and different for most amateurs, the
>>>chemical equipment is not easy to find in the corner store, and it
>>>costs some money when you do track it down. While hcl is readily
>>>available from Home Depot or pool supplies, at the concentrations sold
>>>(28% here in Toronto) it is much more dangerous than fecl or
>>>persulphate. Acid proof gloves and goggles are wise. You need to find
>>>an effective way to generate air bubbles evenly to get a reasonably
>>>even etch. Think and Tinker (IIRC) outlines a good approach with PVC
>>>pipe, but this takes time and tools). To speed etch times, you need
>>>heat. To heat the solution requires a quartz covered heater element,
>>>again not a home depot item, although available cheaply from surplus
>>>sources sometimes. You also need a container to hold the cupric
>>>chloride etchant (the original web article suggests using a plastic
>>>picnic cooler, which is cheap and easily located) but if you heat the
>>>solution I think there can be some hcl fumes which you need to get rid
>>>of without acidifying your work environment with fumes. Do you need a
>>>fume hood? Where do you find an acid proof fan? Where do you safely
>>>vent hcl fumes without corroding neighbors or homes?
>>>
>>>I hope to use this approach, but it is not as simple as buying some
>>>fecl and adding water in a plastic container. The benefits are worth
>>>the costs as far as I am concerned, but IMHO its not quick and easy to
>>>get started.
>>>
>>>Grant
>>>
>>>--- In Homebrew_PCBs@yahoogroups.com, "rolanyang <rolan@h...>"
>>><rolan@h...> wrote:
>>>
>>>
>>>>I had a chance to play around with some CuCl2 (Cupric Chloride)
>>>>etching last Friday and performed a test etch {snip]
>>>>I can't imagine why people are still using Ferric Chloride.
>>>>
>>>>~Rolan
>>>
>>>
>>>
>>>
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>>>
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>>>
>>>
>>>
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>>
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>
>>>
>
>
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