Heat lamp as a PCB oven

Hello,
To etch PCBs faster, the etchants are better to be heated at 40-50C or so.
I was thinking of using a heat lamp, like the ones used in the restaurants to keep food heated https://1.bp.blogspot.com/_8A_0k-xmF4k/S8Uj7hcPLTI/AAAAAAAAAks/zhAYOJDinMg/s1600/Heat+Lamp.JPG inside a small enclosure, to keep the air (and so the etchant liquid) heated.
Would this work?

I worry if these lamps emit any UV radiation, as UV may destroy the protective layer of the PCB and the PCB may start to peel off.

If this is the case, maybe I should better do not allow so much light to hit the PCB by placing an aluminum plate in front of the lamp so that only hot air heats the etchant?

But to be honest I have etched PCBs in front of an incadescent lamp or outside on a sunny day and I had not problems.

A hot plate seems much more comfortable to me.

Or even safer - an aquarium water heater. They are designed to work at warm but not hot temperatures and are usually encased in glass so they are safe in PCB chemicals.

Brian.

FvM said:

A hot plate seems much more comfortable to me.

Click to expand...

A hot plate requires a glass container...I do not know if plastic will survive or let much heat pass through.
I was thinking of the lamp because there is no contact with the setup, heat is transfered through radiation.

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betwixt said:

Or even safer - an aquarium water heater. They are designed to work at warm but not hot temperatures and are usually encased in glass so they are safe in PCB chemicals.

Brian.

Click to expand...

Hm, quire expensive and complex I think...

No, very cheap: **broken link removed**

It's a like chemistry test tube with a heating element inside it so it can be submerged in the etching liquid.

Brian.

neazoi said:

Hello,
To etch PCBs faster, the etchants are better to be heated at 40-50C or so.
I was thinking of using a heat lamp, like the ones used in the restaurants to keep food heated https://1.bp.blogspot.com/_8A_0k-xmF4k/S8Uj7hcPLTI/AAAAAAAAAks/zhAYOJDinMg/s1600/Heat+Lamp.JPG inside a small enclosure, to keep the air (and so the etchant liquid) heated.
Would this work?

Click to expand...

Yes, it would work, but I agree with FVM about using a hot plate. Having good mixing (e.g., stirring) is at least as important. I use a stirring, hot plate.

I worry if these lamps emit any UV radiation, as UV may destroy the protective layer of the PCB and the PCB may start to peel off.

Click to expand...

1) They do not emit much UV, if any.
2) Even if the developed plates were to be exposed to UV, that would not affect their resistance to etching. UV makes the resist soluble in alkaline (basic) solutions. Ferric chloride and all of the common hobbyist etchants are acidic. You could lay the developed plates in the bright sunlight, within reason, and it would not affect the resist.

If this is the case, maybe I should better do not allow so much light to hit the PCB by placing an aluminum plate in front of the lamp so that only hot air heats the etchant?

Click to expand...

See above.

But to be honest I have etched PCBs in front of an incadescent lamp or outside on a sunny day and I had not problems.

Click to expand...

As explained above, that is what I would expect. Once the PCB's are DEVELOPED, don't worry about further exposure to UV. Further exposure to UV only makes ultimate removal of the resist with developer easier.

John

As my etching requirements were low, I would preheat the etchant;
pour the etchant into a heat-resistant plastic bag, and put the bag in hot water, and then, when hot enough, use it to etch.

Swirling the solution helps a lot, or I used a bubble stone [as from an aquarium] attached to an aquarium air pump.

I already have a closed box so I think the lamp solution will work as well as a pre-heated second pan water solution.
The etching tray is transparent plastic, so I am also thinking of covering the base of the box (where the tray rests) with aluminum foil, to help keeping the solution warm.
I believe a single 60W incadescent lamp could heat the air inside the enclosed 30x30x20cm enclosure much higher than required within a few minutes. Maybe allowing for some more minutes for the solution to heat up as well.
It may be that the lamp will provide the copper onto the PCB with more heat (because metals hold heat whereas transparent liquids not so well) so that the copper is acting like a heat re-radiator, heating the liquid even more.

In all my PCBs, etching starts from the sides and progresses on the middle. On large PCBs, the lamp will be closer to the center, which will induce more heat to the center rather than the ends and this may somehow balance the etching. Experimentation is needed to verify this.

It is really very convenient the fact that I could use a standard incadescent (exposure not a problem as you mentioned), since these infrared lamps are quite expensive as I have found locally!