Building prototype boards with SMD components by hand is no easy task, and with modern tiny components the results are impossible to inspect with the naked eye. Professional tools are virtually essential to detect bad solder joints, solder bridges between pins and other defects. A magnifying glass or magnifying lamp can help you find these defects, but the magnification is often not sufficient to clearly see whether there is something wrong. Furthermore, the distance between the magnifying glass and the PCB is so small that there is no room to rework the solder joint under the magnifying glass.
 
There are professional optical aids available for this purpose, ranging from fancy stereo microscopes to inspection cameras or even X-ray equipment, but they also have prices in the professional range. A USB microscope is an affordable alternative, but there are so many to choose from that it is hard to know which one to pick.

A sturdy stand is essential
With a relatively low-cost USB microscopes, the main consideration with regard to usability is not the number of megapixels or the magnification factor. The mechanical properties are primarily what determine whether the device becomes a fixture on your bench or gets tossed in the trash. Most low-cost devices come with a wobbly stand, so even the least vibration of the bench or touching the camera is enough to blur the image.
 
The Andonstar V160 is an exception in that regard – this microscope has a sturdy stand which ensures a stable image. In addition, everything is precisely adjustable. The desired field of view can be set with knobs on the stand, and the focus can be adjusted with a rotating ring on the camera body. The camera is pleasantly small and produces a good, sharp image at a distance of several centimeters above the board, so there is enough room to do soldering work under the microscope. The microscope can also be adjusted to an angle on the stand to allow components and solder joints to be viewed from the side. That also gives you a bit more room to access the circuit board with tools.