heating device for etching process

[Kavitha Seetharaman]

We need a device to heat ferric chloride solution for etching process ...
How it could be heated ?
As it is highly corrosive , the solution should not come in contact with metals ..
the solution is to be heated up to 50 degree celsius....

 

[SirKitBreaker]

It may not get hot enough for your requirements but I have used a tropical fish tank heater for this in the past.

 

[picbits]

As above - have used Fish Tank heaters and Beer brewing heaters in the past for small tanks

 

[3v0]

Most of the boards I etch are small. I heat the solution in a glass bread pan. After it is warm I transfer the pan to a slosher I made from a CD tray drive. It would be nice to have the heat during etching but it works well enough. If the etchant is tired I may have to do a 2nd heat. I use ammonium persuplhate.

It is less mess the FE and when the etchant is exhausted I let it dry out and save the crystals. One of these day I will take them to a recycling event.

 

[Gareth123]

I also use a shallow glass dish and "borrow" my wifes Salton warming tray which is somewhat on the big side for my use as I only use 100 x 160mm boards. It has an area for heating and one for warming. The down side is that it is not temp controlled and if I forget, the solution can almost boil so I am looking for a much smaller unit to which I can add a "simmer stat". It has a glass or ceramic top so it is easy to keep clean. I do not have a "stirrer"so I have to stand over it to keep the solution moving around.

 

[DirtyLude]

I use a plastic dish and have a desk lamp that I put underneath. Hard to explain, but the lamp has a small bright bulb and a flat glass surface. The lamp heats the tray/solution plus shines through the bottom of the board. This works really well as you can see exactly how well the etching is taking place when the light shines through the etched board. Only problem is that I still have to manually agitate the board/solution. Either rock it back and forth or tap the board around in the tray with a plastic poker of some kind.

 

[Gareth123]

What ever works for you. As I said I must find something smaller since my wife doesn't use the tray very often so she keeps it away in a large kitchen drawer with other things so it is a bit of a mission to get it out each time I want to use it and then put it back neatly.

Gareth

 

[cr0sh]

Gareth - while I realize its a "warming tray" - working with etching chemicals around something that may come in contact with food is not the best of ideas...

 

[Sceadwian]

Ferric Chloride? Double rinse, wash it with baking soda and then light soap afterward, worst case scenario you get a little iron in your diet =)
Think I'm joking? Did you know that cooking food on a cast iron skillet will increase the amount of iron in the food by a measurable amount?

The only thing I'd worry about is the soluble copper, but if the tray is dry and cleaned even copper is a needed trace element in the human diet =)

Cr0sh, the risk is only as small as your understanding of it, if you don't know then the risk is perceived as massive.

I got grumpy a bit over this kind of thing when I found out that EPA sewer discharge limits for plating factors are actually LOWER than what a 'natural spring' are allowed to bottle and sell legally. A company I worked for got fined once because their effluent was a few ppm over the limit, worst thing is they don't consider the intake limits, if a company such as that has 'hard water' they're screwed from the start.

I GUARANTEE you that you could find some days and months in isolated spots around any major city where if ALL you did was feed tap water into the sewer you'd be fined.

 

[cr0sh]

I don't think I ever indicated the risk as being "massive" - however:

FERRIC CHLORIDE, SOLUTION | CAMEO Chemicals | NOAA

It is noted as "toxic" and "probably corrosive to tissue". It is considered "hazardous waste"; you aren't supposed to dispose of it by dumping it on the ground or down your drain (likely not the drain because of its corrosive nature to the pipes, and maybe groundwater concerns - though they also note it is used for "sewage treatment and water purification"?).

The MSDS sheet at MG Chemicals lists "Repeated exposure may cause an increased body load of iron, with possible chronic systemic effects.":

Ferric Chloride
https://www.electro-tech-online.com/custompdfs/2010/09/415-liquid.pdf

Likely that's more than the "trace amounts" you would have after using it and cleanup; I still stand by my assertion that you shouldn't be using potentially toxic chemicals with kitchen equipment that may be later used for food preparation.

I'm not telling you not to, I am not telling Gareth not to either - all I am doing is offering some friendly advice; where's the wrong in that?

 

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[Gareth123]

I didn't realise that I was opening a can of worms when I replied that I use my wifes warming tray. The point is taken however about the dangers of the chemicals used. I want assure everybody that the tray is very clean when I return it to its normal storage place. My life wouldn't be worth living if it wasn't.
When you guys talk about enviromental pollution I have to smile because if you came over to the Rainbow Nation and saw first hand what real pollution is happing here you would all have a heart attack. The majority of town councils in this country have collapsed and there is no, repeat no, infrastucture maintenance being carried out in most of them. In the small town / municipality where I live the sewage plant is only functioning at about 10-15%. This results in raw sewage running down the streets. Many of the small pump stations feeding the Sewage plant are not functioning or the pumps have to be switched on manually. At a residents meeting I attended last night it was stated that there are 500 Tons of sludge with a very high chrome content dumped on open ground at another sewage plant and nobody knows what to do with it.
Perhaps these comments are not proper for this forum, however I am trying to obtain a smaller warming tray that I can keep just for my use but they don't seem to be available at least not in this part of the world.

 

[3v0]

If the warming tray is anything like the one I use it never comes in contact with food. No more so then the burner on you kitchen cooktop/range.

In the US these warmers can often be found and thrift stores for a dollar or two.

 

[cr0sh]

Gareth, I certainly understand you live in a very crappy part of the world; it wouldn't surprise me the least to see the conditions you mention. However, wringing one's hands, wondering "what can we do", throwing them up in the air and shrugging it off (ie, passing the buck to the future) - does nobody any good. Unfortunately, that is the way it seems things are handled by our species in a great part of the world, which is pitiful - and ultimately may prove the death of us unless better education on the importance of a clean environment to our worldwide health and longevity takes hold (of course, someone will say "none of this matters with the extreme poverty and lack of food - etc", which is true, to a point - the fact is, its all inter-related; its a network, with network effects - no one part is responsible or helps when fixed by itself; all parts must in a strong position, or none are).

 

[Gareth123]

Hi 3v0

As you say any contact with food is unlikely, it would only be a problem if I was etching and my wife was warming at the same time. Unfortunately we don't have thrift shops here, when we were still in the UK a charity shop would be a good place to look.

Hi cr0sh

We don't think it's a crappy part of the world just yet. There are a number areas where the residents are starting to get physically involved with the problems. In our little town we have formed a residents association with a technical sub committee. I am part of the technical sub committee which consists of a number of Enginneers and Technicians from the Electical, Mechanical and Civil fields and are all registered wit the appropriate bodies. We have carried out a number of audits of the Electromechanical infrastructure mainly the HV/LV distribution and the Sewage and Potable water plants. We have even offered to provide the labour to repair the various plant items but the politics of the country won't allow this to be done.

 

[Sceadwian]

Cr0sh, if you dilute with large amounts of water it's harmless. I've made these recommendations before for those that really want to know.
PH neutralize the solution to a little over water (7-9) The PH neutralizing step is one of the most critical in waste disposal of heavy metal streams, and it's different for every stream but 7-9 is a good generic range. A coagulant can be used but I'm not sure what to suggestion except for sodium bicarbonate (which will also neutralize from acidic conditions). Mix that solution well, and let settle for 24 hours, the liquid should be drawn off and diluted with more water and dumped down the sewer, for proper disposal of the sludge itself finding a local metal finisher that you can dump the few liters you have in will be wonderful. Even a small job shop won't blink it's eyelash at the amount of waste from a hobbyist. Simply dumping it down the drain regardless of your etching solution is illegal.


That's above and beyond the call that most people do, simple legal acceptance would be dilute with large (100-1+) quantities of water and discharge it.

 

[Boncuk]

There are heating foils on the market with different shapes, dimensions and heating power - most of them work with low voltage (12VDC).

Here is an example of a circular heating foil of 170mm diameter and ~17W of heating power.

To find the the foil suiting your needs check out Conrad - Online Shop für Technik, Elektronik und innovative Ideen and type in the search word: "Heizfolie".

There are lots of different foils to select the best for your needs.

I use heating foils underneath and around my "desolder pot", a stainless steel pot filled with soldering tin about 2mm high to rapidly desolder boards with wired components.

Boncuk

 

[cr0sh]

I use heating foils underneath and around my "desolder pot", a stainless steel pot filled with soldering tin about 2mm high to rapidly desolder boards with wired components.

Got any pics of your setup?

 

[Gareth123]

Good Day

Is 17W enough to warm and keep warm a glass bowl of etching fluid (500ml - 1000ml)?

Granted it is much bigger and there is a large area that I don't use but my wifes warming tray is about 500W.

Gareth

 

[Boncuk]

Got any pics of your setup?

I'll post some pictures soon showing the pot in action. Mine uses 220V/800W heating foils controlled by a normal lamp dimmer which I temporarily removed to control a fan to determine minimum voltage for rotation.

Basically the setup is an aluminum frame with a 10mm thick wood (teak) base and a layer of 2.5" bricks for heat insulation.

The device should not be used in closed (unventilated) rooms since the flux added prior to tossing a PCB into the "soup" causes a lot of smoke and smells terribly.

Boncuk