Mic-Fi Wi-Fi digital microscopes - Discoveries in the realm of microelectronics
by Dipl.-Inf. Karl-Ludwig Butte (Germany)
When I began to deal with electronics as a hobby in the seventies the circuits I built usually consisted of three to six transistors and a hand full of resistors and capacitors. These components where soldered on a printed circuit board (PCB) of about 5 cm by 10 cm in dimension. In comparison, a Raspberry Pi Version 3 microcomputer with a Linux derivate operating system and capable of running state of the art office software like LibreOffice, occupies only 5.6 cm by 8.5 cm of PCB space. The build-in 4 core CPU alone integrates millions of transistors. Resistors shrink to the fraction of the size of a pinhead. Needless to say that one has no chance to do any useful work in today’s microelectronics if the tools deployed are not adapted to these dimensions. Tweezers replace pliers, soldering irons transform into soldering needles and normal drills should be replaced by clockmaker tools. But the most important tool, our eyesight, cannot be replaced that easily. Enter the Mic-Fi line of electronic wireless microscopes!
Fig. 1: Mic-Fi WiFi digital microscope family
Electronic microscopes date way back into the mid-eighties. Ten years later the invention of the USB interface simplified the connection of electronic microscopes to the personal computer. But the electronic microscope still had the classical form of an optical microscope which was optimized for the use in biology, medicine, etc. Try to use such a microscope on a PCB mounted within a 19” rack.
The Italian company Italeco srl from Rivoli not only solved this problem by developing the Mic-Fi WiFi digital microscope family , but by adding a full-blown wireless interface and a rechargeable battery pack freed the electronic microscope to go wherever its services are needed (Fig. 1). Join me into the realm of modern day microelectronics and see how the Mic-Fi WiFi digital microscope can be put to good use there. You will be amazed at what is there to discover.
With ever increasing functionality and the demand to take electronic devices where ever its user goes, requires the components, from which electronic equipment are built, to get smaller and smaller. Look at Fig. 2 to get an impression of the available sizes for resistors and capacitors. E.g. a resistor in a socalled 0402 casing is 1mm by 0.5 mm in size. That’s why electronic technicians sometime call these components “chicken fodder”. Although these small casings solve a lot of problems they also raise some new ones. The characters to print the value or type of the component with have to shrink accordingly so that they cannot be read without magnification. A good example is one of the sensors of the so called “Sense HAT”, an add-on board for the Raspberry Pi which transforms the famous single board computer into “Astro Pi” (see https://astro-pi.org/ for details). Fig. 3 shows the Sense HAT with the combined sensor for accelaration, orientation, and magnetic field marked by the red circle. To be able to read the inscription on top of this integrated circuit I used a standard Mic-Fi WiFi digital microscope first (see Fig. 4). Although the characters are now large enough to be read, a little guesswork is necessary especially in the bottom line. This gave me the idea to try the Mic-Fi WiFi digital microscope with a polarization filter. As Fig. 5 shows I was rewarded with a perfectly readable inscription. It is always a good idea to experiment with the different light sources and settings the Mic-Fi WiFi digital microscopes offer.
Fig. 2: Sizes of passive electronic components Fig. 3: The Sense HAT mounted on a Raspberry Pi
One of the ugliest problems in electronics is the one of a so called ‘cold ‘ solder joint. It looks like that the component is perfectly soldered but in reality no current can flow because the solder joint does not make contact. In the old days an experienced electronics technician only had to carefully
Fig. 4: The sensor as seen by the standard Mic-Fi WiFi digital microscope Fig. 5: Using a polarization filter produces better readability
look at the solder joints to find them. But today it takes more than good eyesight to check the solder joints of so called ‘surface mounted devices’ (SMD). Let’s have a look at Fig. 6 which shows a small PCB with SMD components. Everything ok with this board? Alas, not. It is not working as expected. Fig. 7 shows a solder joint which is obviously ok. But look at Fig. 8. This solder joint is a candidate to be of the ‘cold’ type. Because the associated component is a resistor, it can be easily checked with an ohmmeter (Fig. 9). Fig. 7 and 8 where photographed using the Mic-Fi WiFi digital microscope. By magnifying the picture 200x it was easy to spot that this solder joint is foul.
Fig. 6: A small PCB with SMD components Fig. 7: A good solder joint. Picture taken with polarization filter used.
Yesterday, my oldest daughter came home from school and complained about a boring physics lesson. “How can physics be boring?” I asked. As it turned out, the teacher tried to show the students a real silicon chip under an optical microscope. Because he had only one chip available, all 30 students in the class had to come one by one to the teacher’s desk to have a look. To all abundance, the lesson was over before my daughter could look through the microscope. I had luck to own a silicon chip without the usual black plastic housing so that I could show her what she missed in school (Fig. 10). With a Mic-Fi WiFi digital microscope the students could have connected their smartphones to the WiFi-server within the Mi-Fi microscope and would have all seen the picture at the same time.
Fig. 8: A so called cold solder joint. Picture taken with polarization filter used. Fig. 9: The ‘1’ in the display of the multimeter documents that the solder joint does not make contact
Without any doubt Italeco took the electronic microscope a giant leap forward by developing the Mic-Fi WiFi digital microscope family. Lots and lots of new applications open up for electronic microscopes because now they can be used in situation and places where ordinary microscopes are not usable. I’m sure Mic-Fi WiFi digital microscopes will find their way to users in the industry, research & development, universities and schools and the owners won’t know how they ever could be without them. Even amateur and hobbyist users will appreciate the services these devices will give them.
Fig. 10: A real silicon chip as seen with Mic-Fi WiFi digital microscope using 200x magnification.
Links:
www. http://mic-fi.it/it/
de.wikipedia.org/wiki/Datei:SMT_sizes,_based_on_original_by_Zureks.svg
astro-pi.org
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