The pcb will only allow connections which agree with the schematic. You probably are attempting to draw a track which disagrees with the schematic. I cannot read the net name on the highlighted pin of U9 but it looks like KiCad wants that to connect to the highlighted pin of J6. Is that what you are trying to connect?
Yes sir, I’m trying to connect those two, but I cannot be able to. In my schematic this two pins are connected with each other.
The issue is likely too conservative clearance settings. On your screenshot the IC pad clearance ring overlaps with neighbor pin, if you are trying to route a track that is just as wide as the pin, it won’t fit. In fact these settings will generate DRC violations either way, reduce your clearances.
Right on your screenshot there is a note that 0 is a special value that indicates that footprint or netclass clearance values will be used instead. In your case it’s likely netclass. Configure that in board settings.
Edit: and don’t set that to 0 in netclass settings, set it to whatever your board manufacturer can do or more.
I even expanded the size of pad a bit, but it wouldn’t help.
It depends on your design, but another possibility besides or with setting better netclass clerances is to set the footprint’s clearance value but not each pad’s value. Leave the value in the pad properties to 0 and it inherits from the footprint. This is better than setting it for each pad individually because in this kind of small pitched regular footprint (almost) every pad needs the same clearance anyway. If the clearance is larger than the empty space between the pads, you’ll get as many DRC violations as you have pads.
Notice that it’s not enough to set the clearances so that this pad’s value is small enough. Both neighboring pads must have small enough value.
Then the netclass clearance of the track you are trying to create must also be small enough that it doesn’t clash with neighboring pads.
Thank you for your info, sir.
I think the source of problem is clearance (as you were told by others) and not track width. So not be too happy that 0.18 works.
I typically (95%) use track of 0.25 and if it is really needed 0.2.
My advice is to use thinner tracks then 0.2 only if you really, really have to.
Clearance is the minimum distance between copper things at PCB. In 5.1.10 look into File - Board Setup and then Design Rules - Net Classes and for Default net the first parameter is Clearance.
I have it set to 0.2.
Really, because of some rounding problems I noticed in KiCad V4 (I could’t go with 0.2mm track between pads with 0.6mm distance between them I have set this clearance to 0.199.
By the way… read some other threads searching for word ‘sir’. No one uses it here.
Even you are 10, feel here yourself being equal to all others, even if they are 80+.
Do we have confusion about the confusion? I think that other posters solved the original problem, and Ky_Bousong is saying that 0.18 mm is adequate trace width (which is another matter.). But maybe I am confused about the confusion about the confusion. I guess I need another beer.
I think that they solved but OP didn’t followed their suggestions.
When he was told to set clearance in board settings his answer was that he:
- tried to expand pad size and it didn’t helped (where from he got an idea it could help),
- decreased track width and it helped.
I understand it not as another matter but as his solution to clearance problem. He could start such track in his pad because so slim track had enough distance to next pad with too big clearance he still has.
Too deep for my little mind 
Haha. There is no confusion sir. I previously tried what they said. I even adjusted the net pad clearance to 0.05 as well as increased the pad size a bit, but it wouldn’t help, so I decided to use 0.18 track width instead.
Sorry, I still can’t be sure if there really is not confusion sir.
Have you done what I have written:
If you set a pad clearance for the pad you are trying to route track from that pad it can’t help as a problem is clearance between your track and next pad (or pads). The pad clearance you are routing from has nothing to do here as track have a right to be connected to that pad so no separation distance between pad and track is required. But such distance is required between your track and next pad(s). The thinner track the distance to next pads is bigger and we see that when you set track width to 0.18 than track is enough thin to satisfy clearance to next pads. But it is not good solution. I’m sure if you can make clearance being 0.2mm you will be able to use 0.25mm tracks.
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