Soldering can be a challenge if you are new to this field. Mastering it, on the other hand, can be a lot of fun. For beginners, it is important to use good tools and supplies. Professionals are skilled enough to handle cheap equipment. Don’t try to save money at the wrong end. Unnecessary frustration can ruin your hobby.
Requirements:
- A good soldering iron. Be sure to choose one with adjustable temperature up to 400°C.
- Make sure to have a wet soldering sponge (recommended) or at least a solder brass sponge ready to clean the tip of the iron.
- Use a good quality soldering tip. Prefer smaller tips over bigger ones. Make sure to tin the tip using a tinner when it is brand new.
- Choosing the right solder is a science in itself (since leaded solder is prohibited). Buy solder from a well-known quality brand. Some say that solder with a high silver content or special compositions (for instance SN100C) are recommended. Maybe try to get small amounts of different products to identify a good solder that works fine with your iron and your PCBs.
- Buy some extra flux to have it at hand if you want to try it. There are also special sticky types of flux called Löthonig which may be helpful in difficult situations.
- Have some desolder braid and a manual desolder pump ready. Both are very cheap, but can help saving your expensive DIY kit if mistakes happen.
- Optional: a smoke absorber / fume extractor, possibly with an activated charcoal filter if ventilation is not given.
- Optional: A third hand (PCB holder), possibly with a magnifying lens.
- Optional: Consider the light situation. Could a head lamp or a ring light be useful?
- Optional: Other recommended tools: side cutter, digital multimeter (to check connectivity and rule out short circuits), tweezers and a wire stripper. For advanced diagnosis an oscilloscope may be useful.
Various Rules
- Pay attention to the polarity: Some components must be placed in a certain orientation (diodes, transistors, electrolytic capacitors, etc.), for other components (resistors, ceramic capacitors) the orientation does not matter. With polarity-sensitive components, the correct orientation can always be seen from the footprints. However, always double check, as errors can also lead to damage to other components.
- A common rule is to start with the components with the lowest height. So components will not stand off from the PCB when turning it upside down.
- Some people suggest using painter’s tape (a paper-based tape with very low stickiness) to attach components to the PCB for soldering. You can try this out and see if it makes things easier for you. The tape can be removed easily after soldering because of its low stickiness.
How to solder
Place the component on the upper side of the PCB and turn it around so you see the leg stick out. Make sure the component still sits good on the upper side.
Optional: if you experience difficulties you may apply some extra flux before soldering. Don’t forget to wash it away with isopropyl alcohol after soldering is finished.
Touch the leg and the metallic soldering pad of the PCB with the tip of your soldering iron. Wait one or two seconds to make sure both are really hot.
Now touch the leg and the pad with the solder. Try to avoid touching the solder directly with the iron. Better let leg and pad do the melting because that makes sure the solder actually attaches to them.
This is what a perfect solder joint should look like. Full contact with pad and leg. Yet not too much solder.
Bad joints: solder does not fully attach to leg and pad. High risk of problems now or later. Circuit may not function as expected or may malfunction unexpectedly later.
Use desoldering braid, desoldering pump and possibly additional flux to remove the solder and re-solder the components.
Cut the leg but not the solder.
If you used extra flux, make sure to remove it using isopropyl alcohol.
Enjoy the beauty of your perfect solder joints.
Happy soldering!