> --- 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\ufffdC 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\ufffdC
>
> 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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