What not to do; stupidity

[Todd Mulske]

I was so anxious to get my mod up and going that I did something that was really stupid. Tried to make a board work when it was probably ok the way it was. I posted this image of the board after I ran solder beads down the back of the board trying to make sure it would handle the load and not burn up.



With the naked eye it looks good, but when looked at at greater magnification it looks like a time bomb waiting to explode. On the next picture, you will be able to see the bleeding of the solder between the ground and the Vout and the Vout and the Control Trim Pin. I cannot clean this up, the solder has etched into the board.

I will probably chuck this thing and start over with a new board. Hopefully I can get the converter off, but if not I will eat my losses, better that than have a short and take a chance of blowing a lithium ion battery up.

Live and learn I guess, not that anyone ever would, but please do not ever attempt this, it was a stupid thing to do.

 

[Quigsworth]

Keep in mind that you are also seeing a lot of flux...meter it, looks good to me...btw, I don't think building up your power buses is a stupid idea at all...what do you think the ampacity of a 1/32" x 1/8" strip of copper is?...not too much...something to think about when we're soldering 18 awg wire into a piece of perf.

 

[Todd Mulske]

I did meter it; everything checks out good; the only place their is resistance is between Vout and Trim, 2005 ohms; I was told that there is a built in 2K resistor between Vout and Trim so it should be there; all the other channels have no continuity; meaning there is no connection between them or any shorts. It could be flux but it spooks me a little because I do not see the bleeding anywhere lse on the board. Although I did dip my solder iron into flux and stuck the tip of the iron into the last three holes of every channel to make sure that the solder would run through the holes and weld to the pins that I put on the board; I also filled the back of the board with hot glue to make sure there wouldn't be any arc.

 

[Todd Mulske]

I guess i could put it together and use a regular 9 volt battery to test it at first to see how it works. That way i will noy have to worry about li ion batteries shorting out. Wish I had a breadboard about now; will definitely be picking one up.

 

[Quigsworth]

I just picked one up myself, they're great for mock up...I use an old 7.4v 500ma phone charger for a test PS and I also have a set of wooden dowels sized to 14500, 18350 and 18650 to use as batts when I'm mocking up the box...removes all temptation of "just gonna quickly check to see if that batt will fit or not".

 

[Rocketman]

Take a sharp implement (razor blade) and drag down the sides of the solder runs. I used to "cut" simple circuit boards from copperclad boards.

 

[P1NkY]

No worries, Todd! I see no solder bridges in the pic, that's definitely flux residue, as Quigsworth said. Take an old toothbrush and dip it into some rubbing alcohol and brush that stuff away for a nice clean finish. Should have no problems with it IMO!