Cleaning the objects, especially electronic boards, is very important because even the smallest detail will be seen. While durst particles can be removed easily in post processing, many impurities are not removable.
- Remains/fibres from Q-tips and paper towels.
- Hairs.
- Fingerprints and oil from the skin in general.
- Remains from “photographers gum”
- Larger flux blobs and traces.
[Images illustrating the impurities]
Keep the Electronics Alive?
There is always the question if the photographed board or device has to work after taking the photos, or if this is of no importance. If you are allowed to destroy the object, you can clean more aggressively and easily as if they have to stay intact.
Best is to clarify this question beforehand and act on it.
Avoiding Impurities
Best is to avoid the impurities, so there is no need to clean the object. Not all of them can be avoided and you will quickly realise the problem. I will name a few simple avoidable ones in the next paragraphs.
Never use q-tips or paper towels for cleaning. These will leave tiny fibres on the object, which are often not visible with the naked eye. These fibres will be clearly visible in every macro shot, causing fuzzy outlines and shadows.
Instead use foam swabs and a soft lint free cloth. You can get the foam swabs relatively cheap from many sources, just search for “foam swabs”. To get suitable lint free cloth, search for “microfibre cleaning cloth lens”. I recommend to order these products in large packs of 100 pieces. Foam swabs last much longer than regular q-tips, but you have to throw them away after cleaning one board. The microfibre cloths can be washed and reused, but you want to use 20 or more before you wash them in one batch.
To avoid finger prints wear e.g. nitrile gloves while handling the boards.
While Soldering
Always start the cleaning process while soldering the board. Flux can be removed more easily while the board is still warm and the surface is better accessible.
The goal should be to have no large flux blobs after soldering.
After Soldering
The most comfortable way to clean electronic boards is using an ultrasonic cleaner. You will find many resources explaining how to effectively clean electronic boards using a such device.
Alternatively a container, a toothbrush and isopropanol (IPA) can be used.
[Image]
To remove all flux traces, the board has to be completely immersed in isopropanol. Use a small container and fill 2-5mm solvent into it. Put the board into the container and scrub all visible flux traces away. The flux will be solved in the isopropanol, and spread evenly over the whole surface of the board. Therefore it is important to rinse the board after this first step with hot water (50-60ºC).
After rinsing, dump the solvent from the container and rinse the container with hot water to remove all solved flux from it.
Fill another 5mm of fresh solved into the container and repeat the procedure. Rinse again with hot water. Dump the solvent, rinse the container again, use fresh solvent.
As last step, immerse the board again in the solvent to make sure you wash off any traces of water from the board. Use a dry, fluff free fabric (the ones used to clean glasses) to remove most of the solvent from components and the surface.
Now use compressed air to blow any remains of the solvent away until the board looks dry. The rest of the solvent will dissolve in the air. The final result is only visible if the board is completely dry.
Warning:
Summary: Work in a well ventilated area and wear Nitrile gloves. Keep fire and electricity away.
Working with large amounts of isopropanol has to be done in a well ventilated environment. There is also a risk the solvent will catch fire, or in the right air/solvent mixture explode. Inhalation of the solvent will first cause dizziness, flushing and headache. At this point you should get into fresh air immediately!
The solvent can not only be inhaled, it is also absorbed through the skin. Therefore it is important to wear Nitrile gloves working with the solvet. Not only the toxic alcohol is absorbed through the skin, also the way more toxic flux which is solved in the alcohol will be transported directly into your bloodstream.
Persistent Flux Traces
Flux is sometimes very hard to remove, it depends on the used flux and also on the colour and type of solder mask. If you have persistent flux traces, there are a number of cleaning methods I found useful.
- Use hot air to heat the flux, in some cases it will get transparent.
- Use a specialised flux cleaner, there are several good product on the marked.
- Use a solder with a colourless transparent flux and just leave the flux blobs on the board. In some cases, this will produce nicer results as a board with a thin layer of flux everywhere.
[images of persistent flux traces]
Dust
Unless you are able to work in a clean room, there will always be dust everywhere. As soon as you start taking macro shots you will see all these dust particles everywhere.
You have to keep the sensor of your camera and your lens perfectly dust free. These particles are annoying on the raw photos and sometimes hard to remove. The dust on the objects itself can not be avoided, just reduced.
Keep the objects in closed box while you do not take photos from them. Just before you take a shot, use an air blower to remove dust from the visible surface. You can also use the microfibre cloths to clean the objects before each shot, the dust is sticking perfectly in the fabric of this cloths.
Final Check
The biggest problem is the visibility or the lack of visibility of the impurities with the naked eye. You have to use a loupe, microscope or make test shots to see the problem areas.