Why do you need a microscope?
The utility of having a proper microscope and being able to inspect work is of incredible importance to anyone who works on PCBs. However, the benefit of having a purpose-built tool for building circuit boards runs upwards of several hundred or even thousands of dollars.
Even with specialized tools, they can sometimes be very orthogonal e.g., fixed and do not offer much flexibility when used as a prototyping tool. Typically you need an option to move the microscope out of the way, inspect a variety of objects at low to a high magnification range, and an option to connect a camera for digital capture.
In this article, I am going to quickly cover the basic setup that we recommend and what led us to believe this was the right choice. It can be used in a variety of ways like prototyping, soldering, and product inspection. If you are a hardware product developer or interested in DIY electronics, this may be of interest to you. If you would like more information, please let us know. We would be happy to answer any questions you may have.
Ergonomics is the only way
The idea of purchasing a new microscope was a rather daunting task when I first got started. It is likely one of the most important tools a designer and technician alike can have in their toolbox; because it is used frequently to test, modify, and even create new prototypes. For me, this means that I need to be comfortable while I am using it. Really comfortable. Any additional strain in holding a body position adds up at the end of the day, resulting in additional time away from the project and physical strain.
When you use a microscope, it is an extension of your eyes, and any flaw in quality is exceptionally apparent. However, with a limited budget, this can be challenging. To find what was is the most important and focus on finding a product that fits those needs.
The idea of being slightly bent over the eyepiece inspecting a unit under test, for hours at a time, is not an ideal work setup. To be clear: It is not anyone's ideal work setup. It is ideal to have a body position that is easy to maintain for extended periods like sitting upright with the relaxed gaze forwards, not downwards, or hunched over.
For most users, an optical zoom of 0.7x to 180x is far higher than needed and is sufficient for most use cases. However, some may prefer different combinations. The beauty is that most microscopes offer an interchangeable objective that allows users to get a variety of levels of zoom from one set of optics.
The best is to choose something that has the best range. In my case, I was able to find the right balance with .7x-180x, which allows a variety of work to be accomplished. I find the right balance between about 10x to 20x, in my day to day work. Though the higher magnification is not something I use daily, it is advantageous to perform a closer inspection when needed (think defective component inspection and failure analysis). In these cases, it is nice to have and is an invaluable tool for RMA ingress technicians as well.
Once you have started working through the design, eventually, the board needs to be tested. Additionally, it is great to be able to capture a picture of the issues that come up along the way. For this, it is nice to be able to connect a camera for image capture. Some microscopes come with an option to drop a camera as a third lens, or to use it as the primary. In my case, I went with the former option because it was cost-effective, and on the unit-linked below, it can be connected directly to a computer or to a monitor via an HDMI connection. I choose the HDMI connection because the quality appears to be the best overall, and there is no noticeable delay in the image. There is a blur that occurs when objects get moved very quickly but is hardly noticeable under most working conditions.
Out of the way
I wanted to be able to inspect a variety of different objects, and from circuit boards to larger objects like printers, I wanted the tool/instrument to be able to move out of the way.
I settled on a boom armature, or pipe style, to allow the instrument to be repositioned easily and moved out of the way, if needed. As you can see it can easily be extended to most of the mat I use for a soldering on.
Though mostly an afterthought, lighting is absolutely critical to the bench setup. Good lighting is another part of relieving eye strain. Being able to illuminate a workpiece without creating glare in the optics or shadows is really important as well. For this reason, I focused on finding an adjustable LED ring that would allow it to be dimmed if the surface was especially shinny, or if it was hard to see a detail the light can be turned up as needed. The ability for the eyes to focus on a work piece without straining is important and cannot be overstated.
If the LED ring creates too much light, and the dimming option is not sufficient or too coarse, I suggest using vellum or wax paper between the lights as a way to diffuse the light. This will spread it out, without creating hot or intense areas of light that make seeing the object difficult.
Putting it together
In my case, I was not able to find a solution that met all the criteria for a good PCB inspection microscope. I needed to purchase the different components and put them together. One of the most difficult components, that was not available at the time, was an adapter for the lens to the microscope stand which is used to essentially hold the whole thing together. A few minutes in CAD and it was printed on the 3D printer later.
The affiliate links below are for reference, if you have any suggestions, please feel free to let us know.
List of materials
Stand and armature for re-positioning microscope body
Adjustable LED light ring
Microscope with lens (0.7x-180x)