New Project/New Experiment - PCB Etchant And Developer Heaters
idbruce
Posts: 6,197
Hello Everyone
Time to solve another problem. Even though this thread will be related to several of my other threads pertaining to PCBs, this one will have unique subject matter, so I have decided to start a new thread which will discuss the progression of this idea.
To save myself the trouble of retyping the problem, I have copied the stated problem from one of my other threads, and will post it here as a quote.
Even though this problem is related to my own personal economics, I am not necessarily looking for the most economical solution. My main goal is to find a quick, easy, and reliable solution for this problem. Considering that I will be working with PCBs having dimensions 3" X 4" or less, I do not need to be heating up a large amount of developer or etchant. I could get carried away (like I usually do) and waste a lot of time trying to create the optimal setup, but in this instance, I believe I will try to keep it as simple as possible in an effort to save time, because my main goal is to be able to quickly create some nice prototype boards for the Propeller chip and other types of circuitry. And beyond any doubt, I want to get to this point.
As mentioned, since I will be working with boards 3" X 4" or less in size, I figure that I only need to heat up an area of approximately 5" X 7", which should give me plenty of room for my fingers to move around when inside the chemical containers. Additionally, it is also desirable for these chemicals to be constantly moving to allow the input of oxygen and to help remove the unwanted covering. So basically I need two hot plates that are constantly moving. So let's get started.
There are several options for applying heat to a couple of Pyrex dishes, and all have their pros and cons, but like I said, I want to keep it simple in an effort to save time, but I also want it to be as safe as possible. Another consideration is the availability of materials to slap something together. It just so happens that I have two 500 watt halogen lamps from my prior construction days just laying around and collecting dust. Considering that these 500 watt halogen lamps put off a great deal of heat, I will be using these lamps as my chemical warmers. Additionally considering that 500 watts is probably a bit too extreme to heat small amounts of chemicals, I will probably swap out the 500 watt bulbs for some 300 watt bulbs, which I happen to have laying around also. To control the output of heat, I will most likely be using a single pole toggle switch, a 1000 watt programmable dimmer, and a duplex receptacle, all three of which will be housed in an appropriate electrical box or structure. The single pole switch will simply control the power to the programmable dimmer, and the programmable dimmer will become one of those set and forget features that supplies power to the duplex receptacle, and of course the halogen lamps will plug into the duplex receptacle. As for the structure to house all the parts, I have several heavy duty sheet metal forms that a buddy gave to me, and they should be perfect for this project. I can place all parts underneath the sheet metal forms to protect them from any chemical spills that might cause additional hazards, such as electrocution.
I believe I have said enough for now, because it is time to start gathering my parts and thinking this through. But as always, constructive input is always welcome.
Bruce
Time to solve another problem. Even though this thread will be related to several of my other threads pertaining to PCBs, this one will have unique subject matter, so I have decided to start a new thread which will discuss the progression of this idea.
To save myself the trouble of retyping the problem, I have copied the stated problem from one of my other threads, and will post it here as a quote.
As mentioned in the previous post, my biggest problem with making PCBs has been the opacity of the photo masks, however, another problem still remains and it is quite significant. Philmore DATAK Premier Series positive acting boards require a developer temperature between 100 and 110 degrees fahrenheit. If the temperature of the developer is below this temperature range, the board will not develop, and if the temperature of the developer is above this temperature range, it will quickly dissolve the photoresist from the board surface. I have ruined many samples and many experiments have gone bad, simply because the developer was not within the specified range, and todays experiments and sample tests are no exception to these minor disasters. At a cost of $0.39 per square inch (including shipping), repeatedly destroying board material can become a little expensive. Considering that my samples are approximately 1" X 1", I have thrown many $0.39 experiments into the trash bin due to improper developer temperature.
Considering that I believe I now have a solution for my photo masks, I now want to tackle the developer temperature problem, because I am tired of ruining board material. In addition to developer temperature, etchant temperature is also a concern. The etchant temperature for these boards should be with the same range as the developer. So by solving the problem for one situation, I also solve it for the other. So my very next goal is to create a permanent solution to these problems. The samples will have to wait just a bit longer.
Even though this problem is related to my own personal economics, I am not necessarily looking for the most economical solution. My main goal is to find a quick, easy, and reliable solution for this problem. Considering that I will be working with PCBs having dimensions 3" X 4" or less, I do not need to be heating up a large amount of developer or etchant. I could get carried away (like I usually do) and waste a lot of time trying to create the optimal setup, but in this instance, I believe I will try to keep it as simple as possible in an effort to save time, because my main goal is to be able to quickly create some nice prototype boards for the Propeller chip and other types of circuitry. And beyond any doubt, I want to get to this point.
As mentioned, since I will be working with boards 3" X 4" or less in size, I figure that I only need to heat up an area of approximately 5" X 7", which should give me plenty of room for my fingers to move around when inside the chemical containers. Additionally, it is also desirable for these chemicals to be constantly moving to allow the input of oxygen and to help remove the unwanted covering. So basically I need two hot plates that are constantly moving. So let's get started.
There are several options for applying heat to a couple of Pyrex dishes, and all have their pros and cons, but like I said, I want to keep it simple in an effort to save time, but I also want it to be as safe as possible. Another consideration is the availability of materials to slap something together. It just so happens that I have two 500 watt halogen lamps from my prior construction days just laying around and collecting dust. Considering that these 500 watt halogen lamps put off a great deal of heat, I will be using these lamps as my chemical warmers. Additionally considering that 500 watts is probably a bit too extreme to heat small amounts of chemicals, I will probably swap out the 500 watt bulbs for some 300 watt bulbs, which I happen to have laying around also. To control the output of heat, I will most likely be using a single pole toggle switch, a 1000 watt programmable dimmer, and a duplex receptacle, all three of which will be housed in an appropriate electrical box or structure. The single pole switch will simply control the power to the programmable dimmer, and the programmable dimmer will become one of those set and forget features that supplies power to the duplex receptacle, and of course the halogen lamps will plug into the duplex receptacle. As for the structure to house all the parts, I have several heavy duty sheet metal forms that a buddy gave to me, and they should be perfect for this project. I can place all parts underneath the sheet metal forms to protect them from any chemical spills that might cause additional hazards, such as electrocution.
I believe I have said enough for now, because it is time to start gathering my parts and thinking this through. But as always, constructive input is always welcome.
Bruce
Comments
After a little thought, I have come to the conclusion that the halogen lamps are quite a bit of overkill. While utilizing my exposure box, which only uses 60 watt light bulbs, the temperature of the surrounding surfaces easily reach well over 100 degrees. During my last set of experiments involving the film cutter/fuser, I was only using 1/2 of the exposure box as a light box to align and trim my photo masks. This process was considerably much longer than exposing some PCB material, and the glass surface that I was using for alignment and trimming became so hot that it became uncomfortable to work with, so I had to power it down and let it cool a bit. With that thought in mind, I could easily warm up the etchant and developer to the required range with a light bulb less than 60 watts. In fact, I am now wondering whether I can accomplish this task with a 12 volt bulb.
I am not a big fan of transfering equipment intended for one purpose to another location for another purpose, but I have several 12 Volt/1.5 Amp AC adapters that should be fully capable of fulfilling any necessary power requirements for a couple of incandescent 1156 lamps. So I am now thinking of utilizing a couple of 2" X 8" X 8" baking sheets to house a couple of 1156 lamps. The question is: Will an 1156 lamp encased in a 2" X 8" X 8" container generate enough heat to drive the temperature upto the required temperature range?
Bruce
EDIT: Actually, I just discovered that the 1156 is a 27 watt bulb, so I will need a larger power supply or supplies, dependant upon the heat output.
I did not have any 2" X 8" X 8" baking sheets available, but I did have a couple of aluminum 2" X 9" X 9" baking sheets. After finding a couple 1156 lamps, I solder both a positive and negative lead to one of the lamps. I then placed the lamp assembly onto a sheet of glass and loosely covered it with an aluminum 2" X 9" X 9" baking sheet. Approximately 20 minutes after applying 12 volts to the leads, the top of the baking sheet has hit a temperature of 102 degrees fahrenheit, which is well within the specified range. At the present time, I am currently trying to warm up a little water that is in a baby food jar.
This experiment looks very promising
Bruce
However the water is heating very, very slowly.
Bruce
EDIT: The surface temperature of the baking sheet has now exceeded 106 degrees fahrenheit. After I verify that the liquid is capable of reaching the desired temperature range, I will have to apply a little resistance to the lighting circuit, considering that my thermometer only goes upto 106 degrees fahrenheit, and I want to be able to read the temperature with the thermometer that I have available. In addition to the thermometer limitations, through experimentation, I have determined that 104 degrees fahrenheit is about the best temperature for the developer when developing Philmore DATAK Premier Series positive acting boards.
EDIT: It is also noteworthy, that approximately 20 minutes into the experiment, I decided to put a thermometer in the vicinity of this experiment to measure ambient temperature. That thermometer is now reading 64 degrees fahrenheit.
I see this is your very first post. Let me be the first to welcome you to the forum. In this forum, you will find a wealth of information, provided by a wide array of different but helpful personalities. I sincerely hope that you stick around and become a regular fixture here at the Parallax forums.
Yes it does. In fact, this seems to be one of the most promising experiments I have ever attempted, speaking from a starting position standpoint of course.
Bruce
EDIT it said 1 post a minute ago
Have you considered alternate developer chemistry?
For example, K2CO3 may be a little less latent than NaOH in in the resist dissolution process. This may open up your tight time-temperature control problem a little.
You may also want to consider using a graded opacity photomask as a process control tuner. This would allow you to quantify exposure and developer variables.
Also, line width variability attained by the overall process is only going to be as good as your etch process control: don't let up on temperature and etch solution age/concentration control at that point.
Good luck... it's a very complex series of processes.
sm
Yes it is, and that is why I have taken it upon myself to develop a fool proof plan for those wanting to create their own boards, and hopefully I will reap some benefit from my endeavors further down the road. I don't know if you have been following along with my other PCB threads, but two of my main goals are to document everything and keep the cost down as much as possible, with the exception of the board material used. As mentioned in the first post, the board material being used for all of my experiments is Philmore DATAK Premier Series positive acting boards. I chose this board for one main reason and that is that it can be exposed with a standard incandescent bulb. Additionally, to setup a fool proof plan, you must have a standard, and the main stardard to me is the board film that is utilized, otherwise, the whole process varies from film to film. With that in mind, Philmore DATAK specifically states that this film must be developed between 100 and 110 degrees fahrenheit. And believe me, if you go outside this range, developing the board becomes very difficult. I have found that 104 degrees fahrenheit is the ideal temperature for developing this film. Obtaining that temperature is just another obstacle in creating a foolproof plan.
As for the developer, I am using sodium hydroxide because it is readily available in any Ace Hardware store across the USA, in the form of Rooto Crystals of Household 100% Lye Drain Opener. At approximately $4.00 for a 1 lb. jar, this is quite a significant cost savings compared to buying commercial developer.
If you are interested in making PCBs and perhaps some of my thoughts and experiments, you may want to explore these threads:
http://forums.parallax.com/showthrea...-Photoplotter)
ATTN: PCBers SUBJECT: New website and exposure box design for your creative needs
http://forums.parallax.com/showthrea...creative-needs
DIY PCB Fabrication For The Sake Of Science And Education
http://forums.parallax.com/showthrea...-And-Education
Looking For Ideas - Temperature Control
http://forums.parallax.com/showthrea...rature-Control
What is the very best way to get a positive image for PCB making these days?
http://forums.parallax.com/showthread.php?137707-What-is-the-very-best-way-to-get-a-positive-image-for-PCB-making-these-days
Thanks for your input Stephen
Bruce
http://forums.parallax.com/showthread.php?137896-Making-PCBs-at-home
Why is it that you keep following me around and keep telling me that I am wrong in all my threads? Please tell me. Great you love UV exposures, your method is the very best that anyone could possibly ever hope to achieve, and my methods are all wrong. Now that we have established that, will you please quit bombing my threads with your worlds greatest technique, because I am tired of hearing it.
Bruce
I've been making PCBs by a variety of techniques for over 40 years, and I feel that I have something to contribute.
Basically every thread that I have created pertaining to PCBs, you have come into and attempt to shoot down my ideas, saying there is an easier way. You are really starting to tick me off with this communication.
water heater unit, the kind you dip into water that can make it very hot.
liquid pump, can be salvaged from say an old battery operated fountain or .... ahem breast pump.
metal tubes that can survive the developer.
a temp sensor for the prop
a relay the prop can switch on and off.
use the heater in a container of water.
put metal pipes in developer dish, and connect pump to pipes to make water flow in a loop to water container.
have PROP monitor temp in developer.
if temp<desired temp pump on.
if temp>desired temp pump off.
that should work.set the water heating element to something above the temp you want as well.
I did a similar thing for an incubator the eggs sat on cushions with a temp sensor and a coil of copper tube. egg got cool pump a little water, egg got warm stop pumping water.
all but 1 egg of 23 hatched, of course i did this with an Apple 2e.
My technique, which is basically what the more advanced members of the Homebrew PCB Yahoo group use, is much easier, cheaper and produces better results than your technique. You have been messing about for many months, and don't seem to have produced any boards. If I see something I think is wrong, I speak out about it. Here are the forum guidelines:
http://forums.parallax.com/showthread.php?134682-Forum-Guidelines
I don't think that anything I have written infringes them.
I don't see any difference between my criticism of your efforts, and someone suggesting a better way to code an application. It's the sort of thing for which this forum is intended. Also, I don't see anyone else objecting to my comments. If you don't like it, perfect your process in private, and amaze us all!
Wow, that is a very unfriendly and rather tight temperature range.
That would move it outside the patience tolerance of 99% of anyone wanting a final result. (as opposed to an experiment)
As you have already mentioned, very SLOW heating of liquid occurs if you want precise control and when you insert a PCB of varying size, the liquid temperature will drop, and take time to recover.
That adds yet another variable, unless you add yet another heater, also temperature controlled that pre-warms the PCB...
I'll stick with the local suppliers Shuttle Prototype service.
Anyway, good luck! I look forward to seeing the results.
just wait for it to get to temp before you use it.
the pre-heated water being pumped through pipes like that works good,
I once worked with a guy who wanted to etch a large cone.
(Believe it or not a quiescent bath with very slow rate of reaction that was diffusion controlled proved to be the best process. It was run at ambient Temp. This was a 6' cone mind you not a 1" coupon.)
The point is that there is no one right answer.
I happen to like liquid photoresists, for example. They can give you much thinner films than dry film laminated resist but I take a lot of heat since most guys like to stick with the hot laminated versions.
Generally there is not a lot of call for copper lines narrower than .010", so the thicker films are within reasonable process tolerances. As we go to higher frequency chips the narrower lines are going to be needed and therefore thinner resists are going to necessary.
Then again most guys are using 1/2 oz copper. This is way thick for high speed circuits so I tend to use 3micron foils.
Another twist on things is using embedded capacitor layers. Surface mount capacitor count can be reduced by almost 50% by etching discrete bi-layer materials in intermediate layers and interconnecting with vias. I realize that gets out of the DIY realm but it is the way advanced circuits are being designed.
The thing I like about this forum is being able to leverage off of others knowledge.
Keep it up peeps...
and have a Happy Easter. There is great light at the end of the journey!
sm
Do you have some numbers on this, and the spectrum where this starts to 'kick in' as viable ?
Yea, grief for me. I have something to contribute myself, and in my opinion you keep interfering with my contributions.
Forum guidelines clearly state:
I feel uncomfortable.
You have a thread about PCBs, so go contribute your perspective there. I put a lot of time and effort into my threads, and I don't need you telling me my ideas are all wrong, getting me all upset, and otherwise making me feel uncomfortable.
Bruce
So far, we have two different ways of producing PCBs, one using ordinary room lighting but needing precise control of development temperatures and a caustic developer, the other requiring UV light but room temperature development with somewhat less hazardous (but still messy) chemicals. Both have advantages and disadvantages and the latter method is described by someone with a lot of experience in it. Great. As a potential builder of PCBs, I would want to learn about as many methods as possible before choosing one based on my situation and preferences.
It is disrespectful to me, especially when he comes to all my threads and says the same darn thing.. Like I said, I try to provide content, which I am sure is beneficial for Parallax. If Parallax don't value my content, then I will quit providing it.
Bruce
I use caustic soda for development, as well. Sodium metasilicate, which is a lot safer, could be used instead, but is harder to obtain, and much more expensive.
Here is one of my boards:
http://forums.parallax.com/showthread.php?137896-Making-PCBs-at-home&p=1089038#post1089038
I'll be uploading several more examples. Let's see some of your boards.