That is a great idea, but be careful to heat sink the LM317. With a few volts differential and 1 Amp, several watts of heat will cook even a TO-220 version LM317 unless it is on a good heatsink.
My other comment is that for locating voltage drops (not precise resistance measurements) to locate a short, I want to have a stable current but a precise current is less important.
Never mind about my last post with the capacitors, they aren’t working fine. After leaving power applied for a few minutes because I forgot to shut off the supply, the limited current was reached and the voltage dropped low. Also, I experience the same thing when I have the through hole caps plugged in, I just didn’t realize it yesterday.
Now my 4th uC, which is on a protoboard mounted to a breadboard, is also toasted. I saw pins 27/28 glow up and now my programmer can’t identify the target device anymore.
So there’s another clue, I don’t think it’s my PCB’s fault anymore. I only have 2 uCs remaining, maybe 3 if #3 is still good.
I don’t think I ever powered up a bare board, but I did Ohm it out. I like this idea, but if you read my latest post, I wasn’t even using my PCB for the 4th uC and it still burnt up.
For uC #1, I used an iPhone wall wart. For uC #2, I used the programmer as the power source.
For uC #3 and #4, I used my current limited supply. Any time I use this supply I make sure to power it on first before attaching the leads. This is a cheap supply I got off Amazon, and I realize it may be unsafe to use, but it is not the reason why all 4 uCs got toasted. The reason why I say it is unsafe is because even though I set a current limit of say 20mA, there are instances where the display reads something much higher like 100mA.
I’m pretty careful with ESD precautions. I wore a wrist strap connected to a wall outlet and ESD safe mat when I was soldering components. If I want to touch my circuit I will discharge myself on something metal/grounded first, usually my PC case (sounds like a bad idea but pretty sure it’s a safe method).
And in which of the terminals did you plug it?
(Sorry, could not resist).
I once had a loose connection in the Earth lead of the mains wiring. This was not only a silent fault, but capacitive coupling between the other wires can be small enough to not feel any tingling, while still enough to fry electronics, or render your ESD mat useless.
And for what it’s worth, you have my sympathy. I’ve also been in similar situations where the cause of some fault in electronics eluded me for weeks, and fortunately the last time this happened was quite some years ago.
So, this is a commercial board connected to your breadboard the same way as your THT IC and giving the same result as if soldered to your Kicad board.
As I see it:
Something is causing a massive short inside your IC resulting in 27/28 glowing which I find hard to believe because of the construction of ICs.
or, something is causing tracking, in time(seconds), on the boards, resulting in a short between 27/28 and possibly other pins.
Are you sure you are not using an active flux? Some will cause PC boards to become conductive and exhibit a very low resistance and there is not much space between 27 & 28.
As a possible test, strip all the components from one of your previously used Kicad boards (one that had glowing pins 27/28) and check the resistance between the power and earth tracks.
Must have been the right one as his eyes didn’t glow like 27/28.
I use this RA flux and solder. I bought both of these specifically for this project. I’ve never used separate flux before because I’ve never needed to. Again, this is my first PCB and since I used surface mount parts I knew I needed flux. Are you telling me that because my flux is active, I may be shorting things even though I cleaned with alcohol?
Maybe.
Sort of running out of ideas 
Easiest way to tell is remove all the bits from one of the dud boards then check the resistance between the tracks that went to 27&28.
If there is no resistance, connect your power supply to the empty board, put a blob of flux over 27&28, switch on power, and watch. If you get sizzling and/or smoke your flux is conducting…not good.
jmk, I think you’re the winner.
I removed the uC from PCB #2 and cleaned it up with some flux and my soldering iron, then I cleaned it with alcohol. I checked for shorts on this bare PCB and there were no shorts.
With current limited to 100mA, I applied power to the bare board and checked for correct voltage readings at VCC.
Then I put a blob of my flux on top of U1 pins 27 and 28. I applied power and nothing happened, there was no shorting…no current draw on the supply. I thought to melt the flux with my iron. So I melted the flux and gave it power again…
This time I got smoke and lightning. I recorded a video as evidence, it’s in the link below. You probably don’t want to watch the whole video since I didn’t trim it at all.
https://drive.google.com/file/d/1YLSlxWR3WGbX4L_Ll-CuinCWbR5uLWGj/view?usp=sharing
0:00 Setting the voltage and current limit
1:00 Checking for shorts before applying power (melted flux on PCB)
2:00 Applying power
2:30 Current rises, smoking
4:00 Smoking
5:20 Illumination and plume of smoke
6:25 Checking for shorts again after power removed
From the video, you can see there are no shorts on my dollar store meter before power is applied. After the test is complete, there is a short between VCC and ground of -888 Ohms with my meter probes in one orientation, and no short when in the other orientation. I don’t remember which orientation was which, and I don’t know what a negative reading means.
Here is another video after the test and after I cleaned the board twice with alcohol. It still had a short after I cleaned it the first time. You can see the short is gone in this second video. Nothing happens in this video so you’ll want to skip through it.
https://drive.google.com/file/d/1HYrVPEvHRSsxCq46SjzVL2ZAJmpnZ50I/view?usp=sharing
Flux residue can be a good conductor. I clean boards with soapy water and a fine toothbrush
But what type of flux do you use, is it rosin type?
Just the normal solder reel and solder paste types.
Nice fireworks.
I’m pleased we don’t have to blame Kicad 
Maybe those chips aren’t all dead.
Maybe they didn’t respond because their power was shorted.
You will have to lift them all to get rid of all the flux.
Can’t electronics be an enjoyable pastime 
They have an internal voltage regulator for a low voltage core. This core cannot tolerate 5V
Difficult for me to see but, looking at the screenshot suggests checking:
Gap between Pads:
• Solder bridging (though seeing no resistance on meter)
• ‘Gap Width’ and possible arching at 1A
• Pads/solder looks fairly consistent except for the two in question (screenshot).
Quality of the PCB:
• Deformed/distorted traces (resulting in gap issue)
• Expansion of trace under (thermal) load, causing gap issue)
And, for sure, consider @davidsrsb recent post (re voltage regulator)
The list can go on and on and I’ve seen too many issues to list here and it happens in production with Pick&Place and Wave/flow soldering. Lessons learned keeps me from having anything to do with hand-soldered SMD.
No guarantee I’ll get to it but, if you post your files, I’ll consider doing a Thermal FEA (see my post )
I posted this earlier I’m the thread but it probably got lost in the weeds. My project zip file is located here:
https://drive.google.com/drive/folders/1rH_9bEHngeySth9yQ-QKCI5J5p1dckLf
By the way, are the traces too skimpy for 1A/5V? Use the Calculator tool as an aid.
How many layers on PCB?..
[EDIT] got the zip file…
Now I need to clean all three PCBs very well. 91% IPA doesn’t seem to work too well on this flux. Can somebody suggest a different method? I did a search online and people were suggesting things like paint thinner and other harsh chemicals.
Also, I need suggestions on how to remove these SSOPs. I ruined the pins on the one I took off the board in the video. I’m afraid the uC on the first board is probably dead since I wasn’t limiting current on that one. I saw a video of somebody using something called “Chip Quik” low temperature solder. Can I purchase this product at a local store? I’d like to get working on these boards this weekend so I don’t want to order online and wait around…
By the way, I processed the return on Amazon for my flux. Today was the last day of the return period, so I just barely beat it.
You first have to figure out which type of flux you have.
Some flux types are water soluble
I used the calculator during my layout design. I think they’re ok. I don’t think I’ll be drawing a full Amp anyway though
