I am trying to attach female connector to a PCB so I can easily plug/un-plug arduino nano.
After I soldered header I see ~100kOhm resistance in between some pins. I can't understand how is it happening. There are no visual connection on the PCB in between those pins.
I also scratched the PCB in between pins to make sure there is no connection, but multimeter still shows some resistance.
I've already tried to do the same thing on 3 PCBs and all of them have the same issue when soldering is done.
I thought maybe it is FLUX some how connects neighbor pins. I tried to clean it (with vodka :o ) but still the same result.
afedorov:
I thought maybe it is FLUX some how connects neighbor pins...
So did you use flux? You shouldn't have to use ANY flux for this job.
If you did use acid flux, then throw it away and start over.
You should use normal rosin-core electronics solder. Nothing else.
Your pins are badly soldered.
Try this:
Hold the soldering iron to the pin AND via for two seconds (pre-heating both).
Then apply solder to the pin/via (not to the solder tip), until it flows inside the via (2-3seconds).
Hold for another second, before removing the tip quickly.
Leo..
avr_fred:
That white lid on the workbench looks like common plumbers flux which is huge no-no for electronics. What type of flux and solder did you use?
Looks like the same lid for my electronics flux. All the plumbers flux I have used is in a metal container.
If the iron was on too long with too much pressure, the internals of the header could have melted and the pins could be closer together now.
It indeed appears some residue on the board is causing conduction.
It looks like there are no parts on the board (except the headers) so:
I would let the whole board soak in alcohol. Isopropal 91% would be OK but ethyl alcohol from home depot would be better.
Soak it for 5 minutes or so then brush it off with an old (stiff) toothbrush. Repeat a few times.
Follow this by a good washing in hot water and regular dishwashing soap (and the brush). Rinse in hot water then dry as best you can. An air hose would be good here.
Not sure of your flux so I'm not sure which of above will be the most effective, however there is no reason not to perform both.
For the future I would suggest you get a small soldering iron. The one I use has a 1/16" wide tip. You will also need some small solder. I would suggest 0.031" (0.8mm) no clean 63/37 tin lead solder. I do not recommend no lead solder for those just starting out. The lead bearing solder flows better and is less likely to produce a cold solder joint.
I use "no clean gel flux" - el cheapo generic stuff from china. I can soak the part of the board I'm soldering in the stuff, and there won't be a connection between pins like you're seeing here after soldering, without any cleaning effort.
Amazon has a lot of stuff, but sometimes it is hard to know what you are getting. If you get solder flux from an electronics shop it is more likely to be for electronics. Just saying.
I never use added flux for electronic soldering**. If you need flux then the parts are not clean enough (i.e. old parts that have been sitting around for many years). If the circuit board does not readily accept the solder you should clean it with a scotch brite pad (do not use steel wool).
BTW the reason you should use 63/37 instead of 60/40 is the 63/37 has little or no "slushy" phase. It goes from a liquid right to a solid. This makes it very good for parts that could move during the cooling phase of the solder.
** No clean solder has flux in the solder, it should be all you need.
JohnRob:
I never use added flux for electronic soldering**. If you need flux then the parts are not clean enough (i.e. old parts that have been sitting around for many years).
Exactly. But have you ever tried to clean the tin plated pins from 0.1" headers? Guess they will need a little extra flux.
I have soldered for 55+years, a large part of that as a professional consumer electronics tech,
and I never really 'needed' flux in all those years.
I do have it in stock for difficult jobs, but it's usually more of a hassle than a cure.
Learn to solder properly, with a temp controlled iron, and you don't need it.
I frequently hand-solder dozens of 0.5mm pitch PIC chips with just 0.7mm rosincore solder.
Looks no different than reflowing if you do it right.
Leo..
I'm with Leo. The only thing I've needed flux for is some very old non plated (i.e. bare) wire. And at that I had better luck cleaning than using flux.
My old 0.1" headers solder fine with the suggested solder.
However I've not seen the parts you referenced so I guess I can't comment on what you are /were trying to solder.
I'm quite sure if the OP tries the suggested solder they will have no issues with the parts shown in the photos.
I think I actually found the issue that what I considered as a broken MPU6050. I had some weird behavior with this chip and I thought it is because a bad chip. I think those "short circuits" caused issues there.
