PTCL Electronics

Department of Chemistry University of Oxford

Soldering is more complicated than it first looks.

For starters, there are several different types of both soldering iron and solder. This is due to the wide range of areas and targets which need soldering together.

For the soldering of standard components such as DIP sockets, we use our standard bit which has a flat end, and 3mm across. For smaller surface mount components, we use a smaller bit, which reduces the chance of solder bridging the gap between 2 pins. This also reduces the quantity of solder needed. When one of the two components has good heat sinking properties, or we don't wish it to heat up too much, we use as large bit as we can, allowing the heat to only heat the surface.

The type of solder also has an effect. The standard stuff that we use, is about 1mm diameter, and is overkill for soldering of surface mount components. It is however, useful for every other kind of component we solder in. For surface mount components, we use some super thin, silver loaded stuff which works far better. Along with the standard solder, we also have some more expensive solder that is vacuum compatible. This is able to go to lower pressures without outgassing (release of gas over a reasonable period of time) to the same extent.

There are also hidden dangers with soldering.

The more obvious is that the tip of the iron is hot, that is around 300 degrees centigrade, along with staying hot for a period of time after it is turned off/unplugged. This will likely cause burns until the iron has cooled down to a more amicable temperature. This can be alleviated by having the iron held in a suitable stand when not in use, and people testing the irons temperature on a damp sponge before touching, if it hisses or produces steam, the iron is too hot to touch.

The less obvious dangers are that the fumes are toxic, and there can be splash from soldering.

The fume hazard can be reduced by a fume extractor, which draws the fumes away, and filters them (we have some spare portable units if/were needed),

The splash injury is harder to protect against. The eye(s) can be protected with safety glasses (contact glasses are not suitable). If standard glasses irritate your eyes/ears then there are a few options available;

  • A different style of glasses, we have a few designs for test purposes;
  • A colleague/character from electronics to do the soldering for you;
  • A face shield which is more cumbersome than glasses, but protects the whole face;
  • A Perspex screen attached to a weight/magnet (similar to a machine guard), awkward to move tools/soldering iron about.

All options allow the user some protection, however, if the splash occurs to the skin, it can still hurt, however, it is less painful/quicker to mend then the eye(s). If it is painful after a solder splash, cold running water for at least 10 minutes is recommended to reduce pain and further damage (for eyes it would be recommended to also see/speak to the eye hospital/doctor/optician).