What diameter or gauge is the solder ?

 

Ok, that's good. Let's go through the steps.

1. You are using resin core solder.

2. Know the type of solder you are using. Lead free solder is trickier to work with than 60/40 solder. I don't know the regulations in India about using leaded solder.

3. What brand/model soldering iron are you using? Is it the right temperature. 60/40 solder requires 700F.

4. Is the soldering tip bright and shiny? If not you have to clean it and tin it with solder.

5. As others have already mentioned, make sure all corroded, discoloured or tarnished metal is cleaned first before soldering.

6. Are you heating the joint and not the solder? This is the single biggest mistake. You must heat the component leads, joints and solder pads in order for to solder the flow. While the soldering tip is still in contact with the leads and pads, touch the solder wire where the soldering tip meets the component leads. The solder should melt and flow across the joint. Melt enough solder to flow across the joint, no more. Hold the soldering tip there for three seconds and then remove. Allow to cool for 5 seconds without disturbing.

 

What diameter or gauge is the solder ?

Gauge on the cover reads 20.

 

Ok, that's good. Let's go through the steps.

1. You are using resin core solder.

2. Know the type of solder you are using. Lead free solder is trickier to work with than 60/40 solder. I don't know the regulations in India about using leaded solder.

3. What brand/model soldering iron are you using? Is it the right temperature. 60/40 solder requires 700F.

4. Is the soldering tip bright and shiny? If not you have to clean it and tin it with solder.

5. As others have already mentioned, make sure all corroded, discoloured or tarnished metal is cleaned first before soldering.

6. Are you heating the joint and not the solder? This is the single biggest mistake. You must heat the component leads, joints and solder pads in order for to solder the flow. While the soldering tip is still in contact with the leads and pads, touch the solder wire where the soldering tip meets the component leads. The solder should melt and flow across the joint. Melt enough solder to flow across the joint, no more. Hold the soldering tip there for three seconds and then remove. Allow to cool for 5 seconds without disturbing.

2. Yes, the pack says 60/40 and not lead free solder.

3. I'm using this soldering iron http://www.soldron.com/products/soldering-irons.asp
(the second one in the link above rated 25W/230V).
As per the link,the max temperature should be around 380 deg celsius ~ 700F, since I allowed it to heat up for quite sometime I guess the temperature should be ok.

4. Earlier I was using soldering paste(with heated iron) along with the 60/40 solder wire, this paste tends to make the hot tip blackish. However after cleaning the tip is shiny and I'm using it once tinned.

6. Yes, I heated the joint directly and not the solder. Somehow the solder doesn't melt easily or takes too long to melt when I keep the hot rod in contact with the joint. I'm trying to follow what you said in the last post. I'll post some pics once I'm done.

I appreciate that you all are trying to help me with something very basic yet important for electronics.

 

You might try liquid rosin flux instead of paste and dab a little on the joints before you solder.

Then touch the well-cleaned tip to the joint and place the solder between the soldering iron tip and the joint. The joint should solder within a couple seconds. If it takes longer you are not doing it right and the heat can damage the semiconductor.

 

Sorry to be late to the party. Here's another thing to consider: how does the tip of your soldering rod look? It too needs to be clean. Here a damp sponge or paper towel is all you ever want to use, as anything more aggressive such as a file or sandpaper will remove the very thin protective metal layer of the tip.

Heat your iron and wipe it on the sponge, melt some solder on it and look at it: if you see any black spots these need be removed. Rosin core solder will remove some crud there if the tip is not damaged. Add lots of solder to the tip till it looks all nice and shiny... then bang the side of the iron to flick off the excess.

I probably use more solder on my tip itself then on my parts.

Once you have a nice coat of solder on your tip it is ready to solder. The coat of solder greatly helps the tip heat your work by conducting the heat.

You may have heard you should never put solder on the tip when joining wires, but I will first make a small dab of solder between the tip and my work to get things started... then let the iron heat the work some, then add more solder to the side of my work away from the iron tip.

Soldering is indeed more art then science and takes practice. Do not be discouraged.