Beginners question. Do I need or is it recommended to add vias on a board designed for use with Through Hole components? I am guessing that provided the front and back copper doesn’t have island areas there will be continuity through the PTH ground connections. Or am I hopelessly wrong?
Besides the differences between a “via” and a two-layer pad, already pointed out, what makes your pads have solid contact on both sides?
You can’t simply think that the thin annular section of the top side hole is perfectly contacting the component’s terminal (even because the hole will be slightly larger of the pin itself).
The only safe way to do that, as I guess it was in the ancient times, is to solder thrugh-hole pins on both sides (for terminals), and that’s not always possible (think of components with a wide plastic body on components side. For vias there is/was a similar solution with (soldered) rivets.
Another good reason to use double sided plated boards is for mechanical robustness. In fact I’ve seen even humble boards, with a few PTH LEDs, breaking on pressure while mounting, when single sided.
What you describe is ancient (obsolete) technology.
Today plated through holes (PTH) are the norm. Such a PTH already has a conductive “barrel” connecting all required layers.
PTHs are created by some electro-chemical or chemical process after the drilling process. Meaning the board is drilled, then plated. Non plated through holes are then either drilled again or they are left out in the first drill step.
In the first post there were PTH mentioned. I am surprised the direction the discussion went to.
In my understanding the question was why to add extra vias to connect front and back GND zones if they are just connected by some pins mounted in PTH pads.
If you are new to the driving license it can be hardly recommended using a Maserati.
Here are my 10 golden rules for pcb beginners:
Start with analog circuits, filter, timer, oscillators. Simple discrete components allow to learn about footprints. Beside discrete components, some small integrated circuits like OPA are ok.
Choose wired components (THT) and avoid using surface mounted SMD.
Limit your board to one component side (top or front) and one wiring side (back or bottom).
Double layer pcb are todays standard, but ignore them for the very first boards.
To avoid trace crossings use wire jumpers on component side.
(can be done by front layer traces limited to straight shape not crossing any components)
Get in touch with footprint and symbol library. Create your own components and do not trust
downloaded library components until you are sure to see yourself if they meet all your requirements.
Trace width should be minimum 1mm. Also take care for pad size with same minimum annular ring
Do not order your pcb in any internet shops. Print your design using a laser, copy to board.
Etch yourself using mothers goose pot or laundry basket
Drill yourself, solder yourself and test the board yourself. Its the only way to learn that you have
forgotten a simple ground test pin in your schematic design to connect a scope for testing
Never have a project deadline. Try to have a perfect result and take enough time to solve all issues.
If you stuck with anything, take a break, consider asking the community and then start again.
Even experienced designers are good if they exceed estimated design time less than 100%.
For beginners up to ten times the estimated time is still ok. Computers and autorouter cannot help !
After success with several designs, start using double layer pcbs and high pin count
digital components. Go out from your shack to visit commercial board etchers and contract assembly houses.
Why? In my opinion SMD is not only easier to handle during the design phase but is even faster to solder. At least as long as you choose smd parts with large enough pitch to hand solder. At the beginning i would stick with gullwing parts so SOIC and QFP.
Soldering THT means you need to place the part, turn over the pcb and hope nothing falls out, solder, cut leads repeat.
SMD only requires you to place the part and start soldering. Only possible downside is that smd parts are typically smaller and you therefore need small tweezers
As long as you stick with large pitch components (1.27mm) and resistors/capacitors >= 0805 you do not really need magnification nor do you need a special solder iron. A decent temperature regulated iron with chissel tip should do just fine. It is of course easier with good tools. (I would say this is the same requirement for THT as well)
Why? This really seems excessive. 0.25mm is easily manufactured even at home.
This is the worst suggestion you made so far! Dealing with nasty chemicals is simply no longer worth it with cheap board houses available. With a professionally made pcb house you get two layer boards by default, plate through holes (useful for vias) and most importantly solder mask.
The only reason to use self made boards is if one has an interest in this process. (The considerations needed for home made boards are so far removed from a professionally produced one that i do not even see an educational value here. All you learn is that chemicals are nasty, that it is a lot of work, expensive and the result is shitty without investing a considerable amount of time into fine tuning the process and investing in good tooling.)
I learned the oposite to be important. Without deadline people do not work efficiently. They start to obsess about unimportant stuff and never finish a project.
I would start with two layer boards! It is much easier to work with two layer than single layer. If one has the money 4 layer is the way to go. (a continues ground plane makes live much much easier. Not only for designing the board but the result will behave better with regards to EMC)
Assembly houses really are only useful if one makes something that should be sold. Otherwise it just is not worth it. (unless you have money to burn)
I went through this path decades ago and simply don’t see its relevance today. You are talking of a totally different path: resist pen or negative + photo resist + UV lamp or toner transfer paper, ferric chloride or ammonium persulphate, other nasty chemicals like xylene, a drill + steady eye, tinning, and so forth. None of the skills gained here will help you with specifying it to a PCB fab. I think your local council may have some regulations for disposal of the used chemicals too. And as Rene has pointed out, solder mask, a godsend against solder bridges.
I would skip this phase. And since fabs charge the same for 1 layer as 2, and 2 layer will eliminate the need for jumpers, might as well start with 2. Kicad starts at 2 and it takes effort to constrain to 1.
You have to consider the difference between process orientated workflow for education and product oriented workflow. The process oriented approach is to gain knowledge and clearly insufficient for product view.
For self etching the motivation is not to have a industrial grade pcb but to be independent similar than using open source. You can compare with todays DIY 3d printers hype. Neither price of resulting printed parts nor quality is competitive against any commercial prototype service but you gain best insight what went wrong with your design. Same way you will learn best things about feasible board densities, number of required copper layers and minimum clearance not depending from the absolute level. Even the workflow of universities is knowledge oriented rather than product oriented why universities rarely produce competitive products without commercial cooperation partners.
Regarding the matter of timline: Most young people like to pass the drivers license examination after only 10 hours. Only very few are able to do this and the vast majority fails. Therefore best practice for non commercial beginners projects is to practice patience and to be accurate. From both habits you cant have enough while working with computers.
Me too. I think I got a package with ferric chloride from my uncle (working in chemical factory) in about 1970. In 1978 when it got over I experimented with hydrochloric acid with end effect of one drop of (±) 98% acid landing in my eye. Even only no more than one second passed before I started to rinse eye an hour later I noticed my cornea can be slided on my eye separatelly from the what is under it. Then it took me next more than hour to get to doctor.
I also think there is no reasonably argument to follow that way nowadays.
I would start from 2 layers and ordering PCBs in factory.
Also for amateur fotography I would not suggest to start nowadays from buying the enlarger and making your darkroom but just use digital camera.
I struggle to even buy UV copper clad boards for less than it costs me to get a professional quality PCB made in China these days. I would also endorse the comments about the hazards of the chemistry involved and the personal & environmental risks involved. The nasty stain in my kitchen sink was difficult to explain to the wife…
Producing boards at home does have the advantage of fast turnaround - it is interesting from a learning perspective to appreciate the processes involved but the quality control for home etching is generally low. Drilling holes is challenge and the lack of solder mask is limiting. A while back I bought a cheap CNC which does allow you to do isolation milling and makes accurate hole drilling much easier. However, it is quite demanding of achieving a perfectly flat board and the same limitations generally apply. Two sided boards are possible but a bit tricky and fiddly. Whilst it is possible to do a solder mask layer and even a silkscreen, the quality is questionable. Home production is, however, quick - and if you need a board in your hand the same day it can be an effective option. Nowadays, I limit home produced boards for designs that I can easily put on a piece of vero.
So, unless you really need a fast turn around, I would stick to professionally produced boards as the extra work and risks involved to produce a board at home is rarely worthwhile.
TBH, if you etch your own boards, I very much doubt that it will tell you anything useful about possible board densities as you will be limited by your processes not by what is actually possible in a quality controlled production line.