PCB question

[Almighty1]

I am still a novice and I have a question concerning the circuits on a PCB using the attached picture as a example.

Where the blue arrow is, I noticed it is like a island basically it has a gold line as the border and then there is the inside, is the trace actually the border line or is that the inside? While the pads are detached from each other inside the border line, are they all interconnected as in continuity as a circuit?

When I desoldered, I accidentally scratched the border lines as mentioned above, are the border lines actually connected electrically or is it only the things within the border that is connected?

Is there a reason where the red arrow is, it seems to have solder from within the entire area of the gold lines?

Just trying to understand this a little bit better since I noticed with the gold lines, multimeter will not show any connectivity even on the unscratched ones but it seems like I can touch pads within the gold lines and even if they are separated, they have continuity with each other. Thanks!

[budm]

Re: PCB question

The green areas are the solder mask, the section with solder on is where the solder mask was not applied so that the exposed trace will be coated with solder to help it ability to conduct higher current instead of using thicker copper trace which is more expensive.
In the old PCB they do not use any solder mask at all.
http://www.robotroom.com/Silkscreen-...er-Mask-1.html
http://www.eurocircuits.com/Apply-soldermask
http://www.goldphoenixpcb.com/html/S...d/arc_147.html

[Almighty1]

Re: PCB question

Thanks budm, so basically the lines at the outer edge of the solder mask is not really a conductor but rather just a protective coating on top? Am I correct that anything inside the border lines actually will connect with each other. Which one is the actual trace since I'm still trying to learn the different terms used. As seen in the picture, I accidentally ran the tip of the soldering iron and scratched part of the lines as well as the other green color with the later exposing the copper, is there a way to fix this?

[budm]

Re: PCB question

It is conductor (copper) that is coated with solder mask, if you remove the mask you will see copper under it which is the trace for the connection.

[Almighty1]

Re: PCB question

Thanks for the illustration, what are the lines lines surrounding the trace actually called and are they just the borders for the trace? Is there anyway to fix the solder mask if I accidentally scraped it off?

[budm]

Re: PCB question

No need to worry about fixing the solder mask, if you look on how the component's legs are soldered to copper traces of the board, the legs are soldered to the non-masked area of the copper trace.

[SteveNielsen]

Re: PCB question

The solder mask only exists to keep solder from bonding to the traces during the manufacture process.

[Almighty1]

Re: PCB question

Thanks, before budm answered my question, I thought the border lines in the mask was actually the trace itself, didn't realize those lines were really just the border lines of the trace. Isn't the other purpose of the solder mask to prevent corrosion though or is that really not a issue? There were some caps that were difficult to remove so I had to use a mini flat screwdriver on the other side and did manage to get some of the solder mask out exposing the bare copper.

SteveNielsen, that does make sense after thinking about it. Didn't realize solder will not stick to the solder mask where there are no pads or holes.