How to Test a PCB Board with a Multimeter

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For the inexperienced, printed circuit boards, also known as PCBs, are utilized for connecting electric parts together, used for conductive tracks, pads, and others. These components are in charge of mechanically supporting the electronic parts of the product, most of which are soldered to the board. 

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Take note that each electronic product is unique and is made using various parts. Hence, the entire process of manufacturing printed circuit boards is extremely customized. 

What is a PCB?

The first PCB was invented in 1936 by Paul Eisle. Nonetheless, it became famous only in the 1950s when the US military began using the technology in bomb detonators. These days, PCBs are a crucial part of nearly all equipment such as computers, mobile phones, cars, and many more.

It is made of fiberglass or plastic holding ICs and other parts. A great example of a PCB seen in every computer these days is a computer motherboard. The circuit board is green from the solder mask coating the board. Nevertheless, it can be any other color, such as black, blue, and red. 

The Basic Structure of a PCB

The most common PCBs are the ones with copper tracks or interconnect on one of its surfaces. Those boards are called one-layer printed circuit boards. Remember that a single-layer printed circuit board has an outer and inner layer. 

Below is the structure of a printed circuit board:

  • Substrate

Printed circuit boards could be ceramic, metal, or FR4. The latter is typically utilized and is a reinforced epoxy laminate material. It’s the PCBs’ base substrate and is a very durable material. You will find various thickness types of this. 

Other printed circuit boards, particularly the cheaper ones, are made from other materials and lack the durability of an FR4. 

  • Copper layer

This layer is composed of a thin copper foil, laminated to the board with heat and adhesive. This is normally applied on both sides on a double-sided PCB. A double-sided or a 2-layered board indicates there are two copper layers within the structure. 

  • Solder mask

Have you ever thought about why the printed circuit boards are green? That’s because of the layer of solder mask. That’s the top layer above the copper foil, and it offers the printed boards their green color. 

The purpose of that layer is to insulate copper traces from contacting any metal or solder. The normal color is green, but it can also be manufactured in different colors. 

  • Silkscreen

A white silkscreen layer is applied on top of the solder mask. It’s utilized to add any letters, symbols, or numbers as instructions, such as a guide for people to better understand the board. Remember that any color can be utilized and that there are PCBs with black, red, or yellow silkscreen. 

What are the Common Uses of a PCB? 

Printed circuit boards are continuing to drive towards a smaller and compact design with improved capabilities. Other speculations about the future of these circuit boards might be 3D molded plastic boards or integrated circuit chips. 

PCBs offer people a wide array of capabilities, and they find numerous uses in nearly everything electronic or electrical. 

  • Residential 

The most typical use of PCBs is in consumer electronics. In case you didn’t know, they are the core of every electronic device, such as coffee machine, microwave, TV, navigation, workstations, computers, mobile phones, refrigerator, and even your smartwatch. 

  • Industrial 

A lot of manufacturing facilities have electronic parts that need printed circuit boards to accomplish the end design. Keep in mind that printed circuit boards are seen in industrial equipment like ramps, presses, assembly machines, and others. 

In the automotive sector, most vehicle systems like monitors, control systems, medical devices, and navigation are utilizing PCBs. 

  • Medical 

Take note as well that PCBs also have applications in different medical devices. Some of these include blood pressure monitors, X-ray screens, and CT scanners. All the monitors, medical instruments, and scanning equipment contain printed circuit boards. 

How Do You Test a Printed Circuit Board for Possible Faults? 

Testing your PCB is one of the important things you need to consider. Without testing it, you will find many problems and errors which have been ignored during the production process. Such issues might, later on, cause defects and failures in the field.

To prevent the possibility of failure and keep your satisfaction, it’s essential that testing processes are done to make sure the PCB and the parts are completely functioning. Further, having testing procedures through the production stage enables you to determine issues and errors ahead of time instead of finding them out at the final testing stage.

PCB design and manufacture firms often have thorough yet careful testing processes to guarantee the final printed circuit board is of the highest quality. 

  1. Get your digital multimeter and turn the function knob or pick the AC or DC voltage. The PCB and the overall voltage will be shown on the device. 
  1. Unplug the device and the housing. Switch it on and ensure you don’t touch any of the wirings.
  1. With your digital multimeter, check for resistance and voltage. Do a basic test first if you like this step to work out smoothly. Touch the meter probes to the test points present on the printed circuit board.
  1. Check either the resistance or voltage. To connect the resistor’s resistance, connect one probe to the end of every resistor.
  1. To check if all parts are working properly, repeat the above steps for every component available on the PCB. That allows you to single out all the faulty components on the PCB.

Final Thoughts

Troubleshooting a printed circuit board is essential these days. With the increasing demand for electrical appliances, the supply of PCBs has also increased. Hence, a small interruption in the board could make it non-functional or damage other parts. That could easily be located with the help of a digital multimeter.

As the tool is blessed with two probes, it makes the entire procedure to trouble a PCB simple and straightforward.

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