How to solder surface mount components

 

Most modern electronics today have surface mounted parts that are soldered directly to a circuit board, instead of through holes drilled in the board. Many people just simply don’t attempt to solder these components and replace the entire board, which can get expensive.  Frequently, the boards may not be available anymore.  The result is that the device gets junked….for what is frequently a very inexpensive part that can actually be replaced.   The parts can be rather challenging to replace, but it can be done with some patience, and a steady hand.

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This is a CD player from my church that had a bad output.  A small amplifier chip went bad on the output circuit board.  The chip was only a few cents, so I bought a few in case I screwed up.  This was much cheaper than replacing a $300 professional grade CD player.

SUPPLIES NEEDED:

pencil style soldering iron with narrow tip

thin solder with good quality flux.  I tend to prefer silver solder

Soldering wick (if you are removing and old part)

A tiny “tweaker” screwdriver, and needle nose pliars

A magnifying lens if you cannot see close up well.

 

For myself, I can see up close very well if I remove my contact lenses or my glasses…I won’t be able to see far away, but I can get very close to object, so I didn’t need the magnifying lens and did this actually with the naked eye.

 

Remove the old component: To do this, I place the soldering wick across several of the pins, apply the soldering iron, and wait a short time for the soldering wick to absorb the solder on the old component.   Sometimes, you may need to ADD a little solder to start the wicking of the copper braid…touch the solder wire to the wick while applying heat with the iron.

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After enough solder has been absorbed by the wick, GENTLY pry at the edge of the old chip to lift it off the board.  If it doesn’t move, repeat the step above, as there’s most likely too much solder on it still.  You do *NOT* want to rip the copper film off the circuit board with the chip!!!

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Prepare the surface: for the new chip.  Touch the soldering iron to the metal pads where the legs of the chip is soldered to.  You want to melt and smooth out the solder on the pads.  You most likely will need to add a little bit of solder to the pads.  In this image, the bottom right, and the second one from the left do not have enough solder on them, and a little will need to be added.

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Position the new chip  Take the new chip and place it on the board, line it up on the existing pins as close as you can.  The most important thing here however is to line up a single pin on the corner just about perfectly.  In this image, I used the small screwdriver to hold the chip on the board and position it where I needed it.

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Solder the first pin: by touching the soldering iron to the first pin on the chip.  Do not add solder!!!  If there’s enough solder on the pad, the chip’s pin will sink in to the solder once it gets hot enough to melt.  Once this happens, remove the heat, and several seconds later, remove the screwdriver, and the chip should stay fastened to the board.20160213_121135

Repositon / fine tune chip position:  As you can see above, the chip is just slightly crooked.  With the first pin lined up good, it will hold to the board, and we can gently nudge it till it’s lined up with a small screwdriver, or the pliars until it’s lined up with the other pads at the bottom.  Once that’s done…

SOLDER THE OTHER PINS.  Touch the soldering iron to the other pins on the chip, only long enough to melt the solder.  I also like to gently stroke the iron from the pad to the pin on the chip, that way it drags the liquid solder up the pin and assures a more solid connection.  This is what it looks like when finished…both of these chips have been replaced:20160213_130210

 

Reassemble and test!

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