Best products from r/PrintedCircuitBoard

I did learn all of this stuff from experience. Honestly, I had a little bit of a tough time right out of college because I didn't have much practical circuit design experience. I now feel like I have a very good foundation for that and it came through experience, learning from my peers, and lots of research. I have no affiliation with Henry Ott, but I treat his book like a bible . I refer to it just about every time I do a board design. Why? because it's packed with this type of practical information. Here's his book. I bought mine used as cheap as I could. At my previous job, they just had one in the library. Either way, it was good to have around.

So why should you care about electromagnetic compatibility (EMC)? A couple reasons:

1. EMC compliance is often regulated by industry and because a product requirement. The types of tests that your product has to pass is dependent on the industry typically, but in general there are tests where bad things are injected into your board and tests where they measure how noisy your board. You have to pass both.
   
2. EMC compliance, in my opinion, is very well correlated with the reliability and quality of a product. If a product is destroyed "randomly" or stops working when the microwave is on, you're not likely to have a good opinion of that product. Following guidelines like the one I did above is the path to avoiding problems like that.
   
3. EMC design is usually not taught in schools and yet it is the most important part of the design (besides making it perform the required product function in the first place). It also is very hard to understand because many of the techniques for improving your design do not necessarily show up on your schematics. Often, it's about how well your layout your board, how the mechanical design for the enclosure of your board is considered, etc.
   
   Anyways, it's definitely worth looking at and is a huge asset if you can follow those guidelines. Be prepared to enter the workforce and see rampant disregard for EMC best practices as well as rampant EMC problems in existing products. This is common because, as I said, it's not taught and engineers often don't know what tools to use to fix it. It often leads to expensive solutions where a few extra caps and a better layout would have sufficed.
   
   A couple more books I personally like and use:
   
   Howard Johnson, High Speed Digital Design (it's from 1993, but still works well)
   
   Horowitz and Hill, The Art of Electronics (good for understanding just about anything, good for finding tricks and ideas to help you for problems you haven't solved before but someone probably has)
   
   Last thing since I'm sitting here typing anyways:
   
   When I first got out of college, I really didn't trust myself even when I had done extensive research on a particular part of design. I was surrounded by engineers who also didn't have the experience or knowledge to say whether I was on the right path or not. It's important to use whatever resources you have to gain experience, even if those resources are books alone. It's unlikely that you will be lucky and get a job working with the world's best EE who will teach you everything you need to know. When I moved on from my first job after college, I found out that I was on the right path on many things thanks to my research and hard work. This was in opposition to my thinking before then as my colleagues at my first job were never confident in our own ability to "do EE the right way" - as in, the way that engineers at storied, big companies like Texas Instruments and Google had done. Hope that anecdotal story pushes you to keep going and learning more!

Look I do not want to jump in and try to tell you things I know nothing about but I would like to say that maybe you should put this on a PCB and not a perfboard. OSHpark.com is great (and cheep) and you can use eaglepcb for free for something like a class project. Surface mount is a lot easier than I thought it would be. Solder paste is great!!!!! Something like this: http://amzn.com/B005C6H26C Put in where you need it, put the parts down with tweezers and toss it in the toaster oven for a few minutes... let cool and you are ready to go. Mixing surface mount and through hole is not a problem either..... just solder the through hole after you toaster oven it.

Sorry this does not answer your question (I think Enlightenment77 did) but after building a lot of stuff on perfboards and then trying surface mount on an etched pcb... I will never go back to perfs for anything with more than 3 parts.

In my experience searching for similar things, the conclusion I reached was that to get anything better than the T962 (which is utter shit, to be clear) you need to spend several thousand dollars.

I took the plunge on building a reflow oven using this toaster and a Controleo 2, plus copious amounts of expensive tape and some ceramic blanket insulation from McMaster-Carr. Do NOT use the felt crap on Amazon that's intended for cars, the temperature ratings are horseshit and are for "radiant" heat, they won't actually stand up to 2,000deg or even 500.

It took about a week of 1-2 hours per day, but the result was well, well worth it. It's performed absolutely flawlessly the last 2 years and reflows beautifully every time. Lead-free BGAs are no problem, it's been stellar. I probably spent something like $500 on it but you can do it for less. The oven was $200, ceramic blanket roll about $40, extra reflective tape ~$100, plus other odds and ends.

One thing I did with that toaster was use thin aluminum sheet metal to make "shields" for the upper heating elements so there is no direct IR on the boards. Combined with a convection oven, this goes a long way towards ensuring even heating and no hot-spots. Much better than scorching a batch of boards you spent the entire day assembling as I've done with the T962.

The oven I got is probably overkill, it works well but due to the size the reflow cycle runs on the long side. Still within the IPC spec, however.

IMHO it's the only way to go unless you're willing to pony up for a proper commercial oven. The only thing that might be better is vapor-phase reflow which you can accomplish for relatively little (the fluid is extremely expensive however), but that method is also more labor intensive.

Keep in mind that with any oven you should profile it - really just do a test run - before putting in a batch of boards. The worst that will happen if you've done it right is that the solder might not reflow everywhere. When that happens I bump the peak temperature up by 5-10deg C and run it again, but it's better to get it the first time while the flux is still active. Profiling is simple, I take 2-3 random bare PCBs I have laying around, put a few blobs of whatever solder paste I'm using on the pads, and put them on opposite ends of the oven. Run a cycle and if it reflows you're pretty much good to go. Takes 5 minutes.

So yeah, not to pimp my oven too hard but for the situation you're in I'd say 100% build your own. Getting better results will require you spending 5-10x as much.

EDIT: Assembly pics for the curious! I threw them all in there, sorry they're out of order. That grey stuff was the "ULTRA OMG HIGH TEMP RACECAR" insulation from Amazon I used on the first attempt. Do not want. Only after I put it all in there I realized it shouldn't be in contact with a 500deg oven. Gets a little melty. I ended up getting this ceramic blanket from McMaster which is the white insulation you see later. I added it to the window after testing without because it cuts own on heat loss dramatically and makes it easier to hit the right profile. It gets everywhere though and is very itchy, similar to fiberglass insulation, so be warned. Once it's assembled then no worries.

You can also see the shields I added to the upper heating elements to eliminate direct IR.

Sorry for resurrecting a two-week old thread, I didn't see this earlier for some reason.

I don't bother with a lot of the steps you're talking about here. For example, I don't heat/agitate in the etching tank at all. I just wear nitrile gloves and dip the board in a plastic container of etchant, pull it out, dip it in, pull it out, occasionally turning it over... it gets enough oxygen from the air to make the process go fairly quickly. No need to get fancy, especially when working with nasty chemicals. Keep it simple, keep it safe.

My purpose in DIY PCB fab is to prototype a board and verify that a design works with a turnaround time of hours rather than days. So I aim for "good enough." If I want it pretty, with solder mask, silkscreen etc., then I'll send it off to a fabricator.

Building your own spin coater is going to be potentially dangerous work (possibly flinging carcinogenic solvents everywhere, if not the board too) and it's really, really not worth it for solder mask. When I used a spin coater for photoresist at school, we had it going at 3000 rpm, under a fume hood and yellow lights, in a cleanroom. The board was held in place on the spindle by vacuum. You can get really, really nice results etching with a 5 micron layer of photoresist.

But at home, I use a negative dry film photoresist with a laminator and UV light. I use it to etch, not for solder mask, but I'm sure you could use it for that if you wanted.
https://www.amazon.com/INSMA-Photosensitive-Circuit-Production-Photoresist/dp/B01C5SUMAC/
Use cellophane tape to separate the protective plastic film layers. Then you can use a clothes iron on the lowest setting to apply the photoresist to the board, but you'll get more consistent results with a few passes through a laminator set at about 110C.

Make sure you follow the recipe for the developer solution closely (~1% by weight of sodium carbonate to warm water, or about 10 grams per liter). If you use too much of the soda it actually takes a lot longer to develop. Even with the right mix, it's not like those presensitized boards you can buy that develop in seconds. Normally it takes about 5-10 minutes to develop, I use a soft toothbrush and nitrile gloves and just scrub gently in the developing solution for about twice as long as it looks like I need to.

Other random stuff:
I don't do solder mask, but I do put my boards in liquid tin for 5 minutes after I'm done etching them. You can re-use that stuff almost forever. It is kind of nasty, but I don't think it's any nastier than used etchant. It keeps the copper from oxidizing on the hot plate, which can make rework soldering a bitch. I also use a dremel drill press, but drilling sucks so I use SMT/SOIC parts as much as possible.

For the UV light, I don't think polarizing film will help. Sunglasses don't keep you from seeing stuff that's not directly in front of you, right? You'll still get radiation at incident angles. You probably won't need it anyway unless you're doing super fine work, in which case you would need a collimator. I guess you could make one by cutting strips of plastic and gluing them into a grid or something like that, but like I said, I wouldn't bother. If you do this, put it close to the light, you don't want it too close to the photoresist. I'd probably try moving the UV sources farther away first if I was having trouble with exposure angles. You can get really nice results with angles up to about 20 degrees, it doesn't have to be perfect.

I don't like transparencies, and neither does my laser printer, or my wallet. The good ones are a dollar each. Heavy clear vellum (tracing paper) is much cheaper, seems to take more toner, and is still UV transparent. It's a little harder to get layers lined up if you don't have a light table, but still no big deal. The thin vellum you can find at the office supply stores will work too, but tends to jam in a laser printer. I can't find heavy 95gsm clear vellum (65# in freedom units) locally, so I buy it online:
https://www.amazon.com/Vellum-Value-Pack-Pkg-Clear-95gsm/dp/B0086XIBCW

Spend $400 on a proper binocular (or even trinocular if you expect to take lots of pictures) scope with a ring LED to light your work from the top, and a proper base at the bottom.

The SM-3B series (-3T for trinocular) is great. And the more secure double-boom of the SM-4B/-4T series is even better.

I would get the 3.5x-90x combo set which includes the 0.5x and the 2x len attachment. Most of the time, I'm in the 7x-45x range, so if you just get this guy with the ring light, you'll be good to go.

The $400-$600 you spend now will last you for the rest of your life.

Similarly, spend a little more on your first good iron. I bought my Hakko 926 when I was in college. Spent $300 on the setup then. That was about 20 years ago. Still my primary iron.

Sure, you can basically go as simple or as complex as you'd like. The most basic "synth" You could make would probably be a tone generator based on the 555 timer, something like the Atari Punk Console. Music From Outer Space is a good resource for more involved synth projects and the book Make: Analog Synthesizers is a pretty popular resource (you can find pdf versions online). Finally, r/synthDIY has some good resources too.

Aww jeez, Rick. That doesn't look good. I think the technical term for that is "cratered".

My guess would honestly be that the chip itself overheated due to the high current. This is a problem for a heatsink and maybe a fan. I hesitate to say this though, because both the trace AND the chip are utterly destroyed. Maybe a bad solder joint on the chip caused it to overheat?

Are you willing to sacrifice another channel of that board? Might be worth hooking up a stepper in such a way that it's permanently stalled and just running it until it pops, while carefully monitoring the board's temperature. You should at the very least be able to tape down a thermocouple with kapton, and they sell cheap dual K-type thermocouples with a digital readout on Amazon. I've personally had this one to over 700C, and while it DEFINITELY didn't like it and the insulation burned up, it still works. The best solution here is definitely a thermal camera, and if you can afford it you'll be able to pinpoint where the heat is coming from - the traces or the chip.

A good experiment would be to get a thermometer or thermal camera, and hook up one channel with a heatsink and one without. Monitor both chip's temperatures and see how hot they get, again with the motor stalled. The A4983 is supposed to be good to 150C before it detonates according to the datasheet, although it definitely won't be performing well at that temperature. If you see it getting close (within 20C or so) of that temperature, it's likely just not dissipating enough heat.

Would be very interested to see the redesign, if you decide to do one. If you haven't yet read Dave Jones' PCB layout tutorial, I suggest you do. Lots of really great information there, particularly about making your circuit boards neat and professional, not just so they work.

Minor edit: just thinking about the traces, remember that the ACTUAL current can be much higher than intended when you're working with motors or other large inductive loads. A "2A" limit can turn into 20A if something causes a large acceleration on the motor (like a robotic arm hitting a stop and stalling). That'll fry your trace if you specced it for 2A. Make the power traces big and fat. Bigger. Unless you're squeezing the other traces thinner (not just closer), you can go very large with your power traces. You're paying a flat rate for the amount of copper on the board, use it all. Don't squeeze out the ground plane (it's just as important) and don't squeeze the other traces too thin, but if there's any feel free to use it.

The waveshare ESP32 board is a good open source reference you can use: https://www.waveshare.com/w/upload/8/80/E-Paper_ESP32_Driver_Board_Schematic.pdf (I'm guessing you already did based on similarities).

If you don't need the extra accuracy, you can recover 2 gpios by dropping the external crystal. I'm not sure it's that well supported (at least in Arduino) and if you need an accurate clock, you can add a cheap I2C RTC which can share the I2C bus with other sensors. Speaking of sensors, most sensors are available in an I2C version which don't use any additional pins.

I usually also leave off the USB-serial converter and just put a 2x3 header breaking out TX/RX/DTR/RTS/3V/GND. I have a cable I made up that goes from my usb-serial converter (this one) to the onboard header.

Keep in mind that some of the pins are input only, looking at the names on the schematic, I think you took that into account, but verify.

You use really high resistor values in the battery measurement circuit, I know there is an upward limit beyond which the ADC won't work reliably. Since it looks like you are trying to turn on/off the resistor divider, you can use lower resistances. Check out these references (one, two). I used something like Nick's answer to this SE question in my own design. If you're doing a rechargable battery, you should really consider a lipo fuel gauge IC instead though. It'll give you a much better indication of battery charge than voltage alone.

It looks like aluminum PCBs have a different dielectric material between the copper layer and the aluminum, which is what gives them the superior thermal characteristics... very interesting:

http://www.amitroncorp.com/printed-circuit-boards/aluminum.html

Also, I was going to ask if the design has room for a heat sink? I've used thermal epoxy quite a lot for a variety of applications, and been very happy with the results in both adhesion and heat transfer capabilities.

https://www.amazon.com/Krylon-Colormaster-Crystal-Clear-Acrylic/dp/B0009X8LZ4

That is what is currently being used. I don't see how this helps all that much to be honest. They have been doing this for years though.

We also handling the boards to much imo. We get them from our supplier then program them, test them, spray them then mount them. Ideally it'd be nice to find a company that could send them 100% complete to us. If you have any recommendations that would also be appreciated.

> Leica A60F

Ah! That must have been nice :) I may try getting a pair of magnifying glasses like these but I have a feeling I would be disappointed.. though, I suppose that some magnification is better than none.

This was my gateway drug to the 32 ft of workbench space that now contain an oscilloscope, a reflow oven, a stereo microscope, 3 soldering and hot air rework stations, and hundreds of boxes of pinhead sized components along with dozens of sensors for different things.

I'm enjoying my trip down the rabbit hole :D

I linked that video because I used my wife's expensive tweezers to place the components because I was too excited to wait for the proper ESD safe ones later in the video.

Gratz on your boards!

Thanks for the help. I will definitely check it out. The one I ended up ordering was:

http://www.amazon.com/gp/product/007142783X?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

It has some really good reviews so I hope it holds up.

it would need at least detailed sharp, pics of both sides of the board and clear picture or schematics of the wiring.

OTOH, you do get what you pay for. Is $60 too much for being sure that your house doesn't burn down because of a cheaply made junker? Fixing the problems in the cheap one would likely cost more than that.

Finally, a much better solution than these chargers is to buy a normal fast charger for 4-8 AA cells. Some of those chargers will charge a pack in 60 minutes, there were even some that did it in 15 (but those needed special type of NiMh cells).

E.g. something like this:
https://www.vapextech.co.uk/fast-smart-charger-for-1-8-aa-or-aaa-nimh-batteries-lcd-display-vapextech/
That has both fast charging, detection of a faulty battery and trickle charge maintenance, so that the batteries are always topped up and ready to go. That is vastly more capable than the charger you have found and costs about the same.

Or this one - a bit more expensive but the charging time doesn't increase with the number of batteries inserted:
https://www.amazon.com/Powerex-MH-C800S-8-Cell-Smart-Charger/dp/B000LQMKDS

Yes, I get it that replacing batteries is a pain in the backside compared to just plunking the remote on a charger but you get much better life out of the batteries by separately charging each cell.

Based on the recommendation by Rossman; My package had 3 straight nossles attachments to concentrate the air (which i wish would have been 45° ones) but i'm still very happy. The hose could be a little longer; depends on your setup. Heats quick, when docked it cools down (to prevent burning the table).

Quick 861DW 1000W Digital Rework Station with LCD Display

*english

The books referenced by the most presenters and PCB design conferences are
Right the first time by Lee Ritchie http://www.thehighspeeddesignbook.com/
Highspeed design: A handbook of Black Magic - Howard Johnson https://www.amazon.ca/High-Speed-Digital-Design-Handbook/dp/0133957241

Note that A handbook of black magic reads like a text book, it is very long and very boring.
The subject of PCB is complicated and requires an in depth understanding of the physics because just knowing the rules isn't enough convince other engineers that it's the right way to do something. More importantly, in my experience PCB design is always the least bad solution, you have to understand when you can break the rules and what the implications will be and understand if the trade off is acceptable

The part number is called XS3868 and its notorious for not having very good documentation. The one i have says "Ver 3.0" on the back of the PCB.

I found a few things online that really help (this post in EEVBlog forum especially)but nothing definitive that confirms its for my "Ver 3.0" board. Anyway from measuring it myself with a ruler (Really hard to do since its so tiny) i am almost certain that these are the correct dimensions . The 1.3mm is the pitch between pad centers, but the pad width is about 0.9mm (i found a document that says the pad width is 0.7mm but this is definitely not the case for the Ver3 one i got) which leaves a 0.4mm width between edges of adjacent pads. The thickness of the PCB is about 0.75mm (height of the castellations) and the thickness from bottom of the PCB to top of highest component is about 2mm.

Here is a pinout diagram that i believe is correct based on what i could find online. You can ignore that the numbering starts at 16 and just start from 1. Also the ones with different fonts (some of which have question marks) i had to fill in based on another document i found.

I hope this helps. I have already started working on a component library for it in altium which you can download here. But keep in mind that i am a complete novice and this is my first time designing anything from scratch (not just in altium, but in any PCB software). I haven't had much time to dedicate to it since i have finals coming up, but i got started on the pads, i am having trouble gettings the dimensions exactly correct. Also i have no idea if i made the board outline correct. I intentionally made the pads very long to make it easier to solder but i am not sure if this is the correct technique (or if longer pads will actually make it easier or just cause a mess).

Thanks so much for the offer!

Not entirely sure what you're looking for but I've heard a lot of praises for this book : https://www.amazon.com/High-Speed-Digital-Design-Handbook/dp/0133957241

Think you're looking for this: http://www.amazon.com/High-Speed-Digital-Design-Handbook/dp/0133957241

Main things to keep in mind (well there are a lot), are trace-length and matching (for pairs/busses), keeping your capacitance either low, or predictable, watch your reflections (unless you're doing pci, in which case the whole damn bus is reflections).

You'll almost certainly be doing lvds or something similar (unless it's dram in which case god save you), so the key is always trace length matching and try to keep them together. You also have to watch your lower layer, hopefully you can have a decent ground plane to work with, but a broken ground plane can be a problem.

LVDS helps, but otherwise emi is a b.

All this being said imho analog is a lot harder. Digital is about knowing what not to do (and there isn't that much), analog is knowing exactly what to do because everything matters.