Introduction: PCB Designing&etching Overview
There are several ways of designing and etching PCB's, from the simplest ones to the most sophisticated ones. Meanwhile it's easy to get confused about which one to choose, which one will best fit your needs.
In order to clarify some questions like this, I decided to write this instructable, I'm no expert, but I do have some knowledge about PCB's designing and etching.
So, a general overview on some methods, materials, software and tools that might be used to produce PCB's will be taken and luckily it will be able to help you get into PCB's designing.
Step 1: PCB Designing Software
Depending on the complexity of your circuit, it's not suitable designing the PCB by hand, so the support of a specific software that offers the right tools to get the job done is welcome. There are several options of PCB design software, like Proteus Ares, Eagle, Altium and several online option (I'm only describing the most common and accessible ones, but for sure there are several other options).
- Proteus Ares - maybe this is the first program people would think of when it comes to drawing circuits, not because it's the best one, but because it's maybe the most known one. I personally don't like not even use it (although I've already used it for a while), but it's an option to consider when designing PCB's. The great advantage of using Proteus is that you can also simulate the circuit, by using Proteus Isis, this way you can "surely" verify whether the circuit is working or not. On the other hand, some features and tools, are just too confusing to understand and also it's not possible to find every component you possibly need (the libraries of components are limited), but you can create new components if necessary. Another not great news, this is not an open source software, and it's really expensive depending on the amount of tools included in the packet, at least there is a trial version (with several limitations of course).
- Eagle - this is also a popular software when it comes to PCB designing, bad news it doesn't allow circuit simulation, also when first using this software, you might get a little uncomfortable about its interface, which is kinda different, although apart form these disadvantages there are plenty of cool features, such as the possibility of editing the components schematic (related to the symbol of the component) and the package (which includes the pads, the format and the dimensions) in an easy way, which can be accessed just by right clicking the component and accessing the options "open device" or "open package", respectively. Also, there is a large support community, that provides several answers to common issues faced when first using the software, furthermore this community also eases the access to several libraries of components, including official libraries and the ones that were created by users. Good news, this software is got a freeware version (with limitations of course, mainly related to the size of the board and the number of layers allowed), also after being recently bought by Autodesk, Eagle is also got a student version which includes all the features of the program.
- Altium -
- Online programs - there are plenty of online programs intended to PCB designing, in a general way, they are a good option when designing simpler circuits, mainly when you are in a hurry, or if you don't want to (can't) spend a lot of time learning the dynamics of a program. Needless to say that they are really limited to features and possibilities, some are even linked to a specific prototyping service, great news they are always free and easily accessible. which is essential in some cases.
You must have realized that I prefer Eagle, which doesn't mean the other software aren't worth it, it's only my personal option, but actually in general people consider Eagle the worst one when it comes to usability, even though Altium isn't that easy to use too. My main point about Eagle is that it offers incredible tools, that sadly are a bit hard to learn how to use, in my opinion when you get used to its interface, it's really worth the effort.
I didn't list all the software available in the market, I listed the ones I know, so I recommend you to also do a further research on the PCB design software, in case you are really interested in this subject.
Step 2: PCB Prototyping - Methods
After designing the PCB, it's time for prototyping, there are some ways of prototyping your PCB, you can do it by yourself (which is the hardest one, also the one that requires more practice), you can pay for a prototyping service, it might be a local one (if it's available in your hometown) or an online one (which is the most likely to be available for you) etc.
If you decide to pay for the prototyping service, after designing the board, it'll be necessary to generate some files in the GERBER format, the GERBER format is a kind of file that keeps the whole description of the PCB without the need of any external files, in general the PCB design software offer you some tools to help you generate the GERBER file of the PCB, so that is not much of a great deal, also there are tons of tutorials on how to generate a GERBER file, so whenever you are in doubt, just google it, as long as each software takes an specific method to generate a GERBER file.
**********Before requesting the prototyping service, it's important to make sure everything is perfect in your circuit design, so double check, triple check the PCB....., otherwise you might regret it later.
If you decide to prototype the PCB by yourself there are several methods you can use, the focus will stand on three methods, maybe the most common ones, that are the toner transfer method, the photolithography method and the "artistic" method.
- "Artistic" method - if your PCB is simple, or maybe you if you are good at drawing, you can simply draw the vias and trails manually, by using a permanent marker, of course respecting the dimensions of the components, I've already done several PCB's this way, some of them turned out to be good ones, but I no longer use this technique, as long as the PCB's started getting more complex, so I would say that this is an entry method, and considering the availability of several other methods, I don't think it's worth using this method whenever the PCB's start getting more complex.
- Toner transfer method - I think this is the most common method among the makers, it's kinda simple and also doesn't take a lot of tools to be performed, which would explain its popularity. There are different ways of transferring the toner to the virgin board, in general makers use heat transfer, in which the layout is printed, by using a laser printer of course, in some specific kinds of paper (like glossy paper, transparency film etc) that allows the "complete" transfer of the toner to the virgin board, then the toner is transferred to the virgin board normally by heating the toner against the cooper board using a cloth iron. There are also other ways of transferring the toner to the cooper, such as chemical ways, and also some makers direct print the toner in the copper, by fitting the printer into supporting this feature.
- Photolithography method - in my opinion this is the hardest method, and also the most expensive one, but if you perform it correctly, the results will be just impressive (actually, this is the method mostly used in professional PCB's). In this method, photo sensible paint is applied uniformly on the virgin board, after it the paint is exposed to UV light, with exception of the pads, vias and trails which are covered by a photomask (that correspond to the circuit layout), finally the paint is developed, only staying in the areas that weren't exposed to the UV radiation, which are the pads, vias and trails.
After getting the vias, pads and trails transferred to the cooper board, whatever method you used, it's time for etching, also there are several ways of etching, but they basically consist on eroding the exposed cooper from the board by using a chemical solution. The most common solution used is Ferric Chloride, but there are also other options, that are got pros and cons as well, such as Cupric Chloride, Hydrogen Peroxide – Sulphuric Acid etc. Anyways, no matter the etchant substance you decide to choose just make sure to take the necessary safety protocols to use them, as long as in some cases you might deal with some powerful acids.
**********Again, there are more possible ways of prototyping PCB's, so if you are interested in any method it's really recommended to do a further research on it, there are a bunch of tutorials out there and even in instructables, so feel free to go for them.
Step 3: PCB Prototyping - Materials/Layers
After getting to know some procedures on how to prototype PCB's, some questions might come up, such as, how many layer should I use? When is it worth using a 2 layer PCB?
I think that there is no definitive answer for these questions, but when prototyping PCB's by using DIY methods I think it always better to run from 2 layers PCB's, as long as they are harder to do and take a lot of extra effort, even though there are situations in which there are no options, maybe because of the circuit complexity or maybe because the circuit is got components that are mandatory to be in the bottom layer and also components that are mandatory to be in the top layer, so there is no way out, but whenever possible I consider always better to go for 1 layer PCB's.
On the other hand, when paying a company to prototype your PCB, I would always ask for a 2 layers PCB, as long as the average cost of 1 layer PCB's and 2 layers PCB's are really similar if not equal, also 2 layers PCB's eases a lot the routing process of the circuit.
PCB's with more than 2 layers are possible too, but they are quite unlike for makers to need them, as long as only highly complex circuits are got these kinds of PCB's, also they are highly expensive to produce, which classify them as a not much affordable option.
Also when prototyping you can choose what kind of virgin board to use, there are lots of options, but the most common ones are fiber glass boards and phenolic fiber board. The phenolic fiber one is a bit cheaper than the fiber glass one, but not that much, in general the fiber glass board is got better mechanical characteristics and also looks better when finished. But in general these characteristics aren't much of a big deal when prototyping some kinds of circuits, but it's actually good to know the available options.
Step 4: PCB Prototyping - Tools
There are several tools that can help while prototyping your PCB, but the basic ones are the:
- Solder iron
- Electronic pliers
- Electronic tin solder
- PCB hand drill press
- a permanent marker (in case you are relying on the artistic method to prototype your, or maybe to correct possible flaws in the toner transfers)
These are the minimum tools you are supposed to have to prototype a PCB, but there are tons of advanced tools that might also help you prototype, such as electric drill machines, solder stations etc.
Step 5: Summing Up...
Nowadays the access to paid prototyping services increased a lot, they became more affordable and easier to use, so whenever you need a professional looking prototype, just go for it, as long as much more resources will be available while designing your PCB, which means less limitations, on the other hand if you are looking for a fast forward prototype, you can just do it by yourself in a much faster way, but with more limitations and maybe a result that is not so good as the paid one, but that will fit your needs.
Considering the current scenario it's kinda a personal choice too, considering that paid prototyping services became highly accessible.
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