I am having a quiet war with Oregon Rail Products 5 positin PRR signal construction. The PC board on which the LEDs are mounted is a bit smaller than the size of a 5 cent coin and I am challenged to keep each solder joint from jumping onto its nearesr neighbor. I have a 25w soldering iron which I considered small, but through the magnivisors, it looks huge and is difficult to control.Could I tin the LED leads first do you think ? Any suggestions from anyone who has tackled these signals or similar task will be most appreciated.
Tin leads and board.
Get a smaller iron 10W to 15W
Clean tip, and tin tip with a very very small amount of solder
you should NOT be adding solder to the joint, just reflowing the solder on the board and leads.
I would get a hotter iron, something with a fine point, and clean it when it is fully hot by wiping it forcefully on a roll of paper towel. Then do a very fast dip into acid flux. When the tip is shiny, it is clean.
Find a safe way to get the soldered area free from finger-print contaminants and other foreign matter that will impede the adhesion of the solder.
Also, use very tiny spots of acid flux where you need the solder to adhere. This is the critical point; if you smear it it will help to wick the solder where it is smeared. Next, get coreless solder that is about as thick as a 22 gauge wire. Tin the tip, tin the leads, and then place the leads securely against the board. Apply the tip of the tip reasonably firmly against the lead for a count of 1,2,3…and lift it off. If your iron is hot enough, you will get the flux sizzle in a couple of seconds at most. That is when you lift the iron. Let the lead cool for a couple of seconds, and that should be it.
Because of the acid in the flux, wipe the area with a Q-tip dampened with a solution comprising 1/2 cup of distilled water mixed with a pinch of baking soda. Dampened, not dripping wet…we don’t want either the acid or the basic sodium bicarbonate solution left to do nasty things when we are asleep.
Never use Acid flux near a PC board. If you do not get all of it off the board (100%) the board and the components will have major problems.
I have used .032 rosin core electronics solder, the type for doing fine computer board soldering, to solder anything electrical.
The big thing is to tin the PC board and the components to be soldered to the PC board before trying to solder them to the board. Just using fine (400 grit) to clean the board if there is any type of discoloration to the copper on the board will help. Then just wipe the board off with a paper towel and then tin the board. Yes the fine sandpaper is a little radical but I have salvaged quite a number of things this way (especially after a component explosion).
The main thing is a clean tinned tip and tinned components.
If the solder flows over to an adjacent trace just use a sharp x-acto knife and cut the track back open, but do this carefully to keep from getting cut yourself and to not cut the PC board copper where you do not want it cut.
BOB H – Clarion, PA
Never, never, use acid flux on anything electronic – resin flux only. Acid flux will destroy a printed circuit board and there may be enough left on the board to cause severe damage despite your best efforts to neutralize it with baking soda. Some of the flux will be trapped under the solder and eat away at the solder joint from within.
If your soldering iron has an easily replaceable tip and you have extras, file one down to a needle point to use on this particular project. Filing a tip should have no detrimental effect on the iron’s performance.
Thanks for the tips (so far…) fellas. The challenge seems a little less daunting now.
This sort of exchange makes this forum a great place to belong to.