Tuesday, 1 September 2009

Silkscreen and solder

Some photographs:

here are all the packages required for the opto endstop board laid out

and here are the individual components placed around the bare board,

and here are the undersides of the three finished items

I know the photo' is poor, what with being blurred and having terrible reflection off the auto-flash, but you can just about see the scorch mark at the resistor on the first one I did (on the left), before I swapped to a finer tip on the soldering iron.

Now I need to determine which connectors are what on the "ethernet" socket and get myself a 5V power source to check all the opto endstop boards.

Here is a better photo' (new batteries in the camera, daylight (of sorts)) showing the first board:

The slight scorch-mark is (on the middle resistor) just above and to the right of the central fixing hole.


  1. That last picture hurts my eyes! I can't see what is actually burnt. It looks like the dark spot is over the copper fill? You can't scorch copper! Maybe you could scorch the solder resist but it would need to be a very hot iron. Are you sure it is not just burnt flux?

    If you manage to scorch the fibre glass it can be a problem as it carbonises and becomes conductive, but I never seen a soldering event do that, just components overheating.

    Is it a temperature controller iron?

  2. Erm, yes, sorry. I need to get a camera to overcome camera-shake, and one on which it is easy to turn off the flash!
    It isn't a temp. controlled iron.
    Is solder-resist just the red colouring on this board?
    On the leftmost board, there is a fixing hold middle left, and the scorch mark is just diagonally down and right of that.
    I don't know if it is just burnt flux. How do I tell?

  3. Yes the solder resist is the red covering. It is more often green.

    Burnt flux is black crusty stuff that sticks up above the surface of the board. You can usually scrape it off with a fingernail leaving the resist underneath. If you have burnt the resist, scraping it will reveal the copper.

  4. It is just burnt flux as it is raised a bit from the surface and you can see un-burnt flux next to it. It probably burnt on the tip of the iron and then transferred to the PCB.

    It isn't anything to worry about. You can get flux cleaners, but some of them are pretty nasty. You can also just chip it away with something not too sharp, so as not to remove the resist underneath.

    With very sensitive circuits flux can absorb moisture and create leakage but with this sort of circuit indoors you will have no problems leaving it on.

  5. Pretty neat and a good job for a first-timer!

    My first soldering attempts were a lot worse.