As head twidget and a navy authorized micro-mini repair tech I thought it wise to talk about the art of soldering. There are many ways to solder but only one right way.
I thought we would start with a overview of soldering. Basically you are connecting two metals with a third that acts as a glue. Notice I said glue, soldering is not welding. Welding is two metals that have been melted and intermixed with the same metal or an alloy. The glue or solder we use is a lead, tin compound or it may be one of the lead free compounds.
The tools to have available are:
- Soldering iron, match the wattage to the job. 27w or less for PC boards, 27-50w for medium connectors, 50-100w for large connectors.
- Solder, lead free if you can get it, 63%lead-37% tine otherwise. Avoid the 60-40 as it has a very wide plastic range and may allow for cold solder joints.
- Soldering flux, even thought the solder has a core extra is better, rosin only, liquid preferred. Never use acid flux as this will leave a residue that eats aways the other metals.
- Distilled water for the cleaning sponge.
- Isopropyl alcohol not rubbing alcohol, this leaves a lanolin layer on every thing, (good for your skin but bad for soldering). Used for cleaning the solder and connecting areas.
- A small fiber cleaning brush, to scrub a bit if needed.
- Paper towels.
- Small and large clamps and clips to hold the work if needed, remember the connectors will get too hot to hold with your fingers. Plus you will have the solder in one had and the iron in the other.
- Small wire cutting pliers and needle nose pliers, a sharp knife and wire stripper.
- Good ventilation as the fumes are toxic and should not be inhaled directly.
- Good lighting, you need to see what your working on.
Every thing should be clean, the tip in the iron should still be it’s normal shape, it loses metal to transmigration to the solder. After it is heated then clean off the large amount of gunk with a damp paper towel then use the sponge. Tin the tip with clean solder and keep it tinned removing the excess only when you begin to solder.
Before using the solder dampen a paper towel with some alcohol and pull off a foot or so of solder then wrap the towel around the solder and pull it through. This will clean any contaminates off the solder before use.
In the next installment I will talk bout proper amounts of solder to use and how the joint should look. When being trained to do this for the Navy I found out that as an example of the need for correct soldering practices a radar surveillance plane was reworked to the correct method and 700 pounds of solder was removed from the planes weight!