I originally (In another instructable) had successfully soldered a flat flex cable to the motherboard of an ipod. However, I decided to add a little more solder for strength, and bridged a connection. I thought I could accomplish the same thing with tiny wires. In the end, the assembly was too fragile to handle the manipulation. I successfully connected one wire of the motherboard to one wire of the connector before they started to pop off, and I gave up.
I am posting this for inspiration, so you can read it and see what you can do, if you are faced with a similar situation. If I had to do it again, I think I could have been successful by using a hair-thin wire, and directly connecting the flat cable to the motherboard.
Step 1: Preparation of Wire
Here I tin all of the wires. Tinning is important. Tinning is where you strip back a portion of the insulation (I usually stripped back 1/32" for this tiny project) and dip it in flux.
Flux, when heated by the soldering iron, becomes acidic and cleans the metal so that solder will stick to it. Solder will not stick to dissimilar metals without flux, even with good cleaning. You need flux.
So, I dip the tip of the wire in the flux, then touch the tip of the soldering iron to the wire. A tiny puff of smoke is seen, but really there is no difference in the way the wire looks.
Before I soldered these tiny wires to the connector, I made sure even though they were tinned, that there was flux on them when I touched them to the connector. This improved solder flow.
So technically the wires got a flux-dip two times, once to tin, and another time to solder. Flux will often act as a buffer between two solders, to help them stick, and makes a better, stronger connection.
In the previous instructable, I showed how I used a dremel cutoff wheel to shape the tip of my soldering iron.
Step 2: Soldering
Here you can see the connector against a dime, for size comparison.
I used nothing special here, an ordinary magnifier lamp, an ordinary 30 watt soldering iron.
I used toenail clippers to cut the tiny wire.
I went from top to bottom, left to right. I used a steady hand, and had to maneuver the wires many times, plus I had to have a backdrop to press the soldering iron tip to the wire, against the connector.
Step 3: Close Up Inspection
Here is a microscope look (75x magnification) at the connector.
One of the wires was too long, in fact, they all were, but two looked like they were touching. Electrically, believe it or not, they were not making a connection. But I didn't want to take a chance.
I desoldered the wire, cut it, then re-soldered it. I ended up desoldering every wire, then resoldering each one three times. It's not impossible to do.
However, the problem here friends, is the size of the wire. It's small, but it's way too big. I do not know what gauge wire it is, I apologize. However, human-hair thickness would work much better.
Step 4: The Easy Part!
Now comes the easy part. Soldering the wires to the motherboard. The connection are much farther apart. It was not even a challenge.
However, I did need to make sure that there was flux on the wire when I touched it to the motherboard (After tinning) to get good adhesion and head conduction.
The soldering to the motherboard went very quick.
Step 5: Trouble!
If you read the previous instructable, you will remember that one connector was destroyed, and another bent. I had to bridge connectors with an individual strand of a wire. This really overstressed the connection point on the motherboard.
Due to overstressing of the connection on the motherboard, the connection point on the PCB was ripped off of the motherboard.
If you think that this means the end, think again!
You need a good meter with a continuity checker (Preferably audible!).
I also sharpened the test probes.
I pushed one probe into the contact (See microscope picture), and tried random points on the motherboard to see if there was a solderable connection. It turns out, on the other side of the motherboard, on a TINY component (Impossible to solder, nearly), and also, thank GOD, on the same side, next to the battery. (See picture)
Step 6: A Mess
Here is the big mess.
I sorted through it with tweezers.
I have 8 connections on the motherboard, and 8 on the flexible connector.
Here, friends, is where I gave up. I managed to connect one connection. While going through the other wires, one wire came desoldered. Then, another wire.
Please keep in mind I had to re-solder every wire 3 times on the connector, and a few wires on the motherboard. the wire I used is simply too big. I am not sure what gauge would be better (50 gauge?).
I am going to try this again with thinner wire that won't rip out of the motherboard or the connector.
Right now I have a 4 gigabyte thumb drive with a good looking, but worthless screen. It is so frustrating. However, I believe with thinner wire, it will work perfectly!
I am not giving up. However, another connection point on the motherboard ripped out, so I have to trace it, too. But I will find where it connects and I will repair it when I get smaller wire.
The biggest problem was trying to bend and manipulate the wires to meet up to each other. It was nothing but trouble.
To be continued!
While removing the wires, three more connection were ripped form the motherboard. I was able to trace ONE connection to a solderable point, but I was unable to find any place on the motherboard where the other two could be soldered. Unfortunately, I may have reached the total end of this project.