How to Identify Electronic Components in a PCB Layout

 Person using a magnifying glass to look at a PCB

If you’re a designer who has started a new job and is just starting to dig into existing designs, then you’re probably familiar with the time required to come up to speed. Existing products and old designs often have a slew of components that are tough to identify just by looking at them, especially when you don’t have design documentation available for an old project. Sometimes, you’ll have access to some of the design documents, but other times you might just have a collection of components that need to be identified.

Learning how to identify electronic components involves more than just specifying part numbers for a component you find in the lab. Tasks like reverse engineering a design, rebuilding documentation for an old design with new components, and debugging an old product that has no documentation all require the same set of strategies for identifying components. If you find yourself in this situation, there are some online resources you can use to help you identify electronic components and find suitable replacements.

Identifying Electronic Components

Most electronic components will come with some information you can use to identify each component. At minimum, you’ll have the information needed to identify the specific manufacturer and part number. In some cases, such as with SMD passives in small packages (0201, 0402, etc.), there won’t be any way to identify the specific MPN, but you can at least take some steps to identify the value of the component. In other cases, you won’t see any MPN on the component and you might not have documentation for the design, so you’ll be forced to try and find a replacement component.

Looking at the PCBA

When looking at the PCBA you need to debug or reverse engineer, you can usually see component information printed directly on some components. Integrated circuits and larger radial/axial capacitors will have some markings on them that will state an MPN, component value, manufacturer, or other information. You can then put this information into a search engine and locate more information about the component.

MPN for a Broadcom chip

The MPN for this Broadcom chip is BCM6358KFBG. You can put this number into a parts search engine or distributor website to find more information about this component

If you have any through-hole resistors, look up a color code to read off the value of the resistor. You won’t be able to see the manufacturer, but you can start looking at distributors to start searching for replacements if needed. Other passives and a variety of smaller ICs may not have a simple method for extracting a component value or part number, so you’ll need to rely on any design documentation to identify a particular component.

Looking Through Design Files and BOM

If you have the design documentation available for your PCBA, simply match the reference designator on the board with the entry in the BOM. As long as the BOM is complete, you’ll see a supplier PN of an MPN for the component. This can be done for any component as long as the reference designator is visible on the silkscreen layer.

Entries in a BOM

You can match reference designators in the PCB layout with entries in the BOM

In other cases, you might not have the finished BOM and only have some design files. In this case, you may need to open up the design files until you find the specific component. As long as the libraries are complete, you can point to the specific component in the design data and pull out the supplier information. This will give you the MPN, supplier PN, or both. Again, this can be done for any component in the PCBA.

Checking the BOM for the MPN

Check the BOM for the MPN

It’s always a good idea to rely on documentation if it’s available and known to be accurate. When reviving an old design, make sure you verify the old documentation is correct by comparing the footprint on the PCB with the entry in the component datasheet.

Unfortunately, there are many times when reviving old designs or reverse engineering a board that the original design documentation is not available. In the case of passive components, you can detach the component and test it directly with some simple measurements. For ICs, you won’t have the luxury of gathering any standard measurements, and you’ll have to get creative if you need to identify an electronic component in this specific case.

What to Do When You Can’t Identify ICs

ICs are a special case where you can’t simply gather a standard measurement to test the component in the same way you would with a passive component, and you may not be able to identify the MPN for an IC. When the design documentation no longer exists and the component markings have been totally scrubbed, you won’t have any way to find the MPN. You also can’t run a test to determine the component unless you’re willing to risk destroying the component.

If you originally encountered a component in a PCBA, and you need to find information for the part in question, the best you could do is identify the function of the component (MCU, etc.). You can probably also identify the pinout by looking at the other components connected to the chip, and you can usually identify the power level just by looking at other components and markings on the PCB. In this case, it’s advisable to simply look for a replacement.

Ultra Librarian search engine

The best electronics search engines will help you find replacement components when your parts can’t be identified

If you’ve determined the function of the component you need to replace, try using an electronic parts search engine to find new components. You can find the components you need when you search by specification, function, part type, or manufacturer. An electronics search engine can also give you access to verified PCB footprints, schematic symbols, and sourcing data for your design.

When you need to find ECAD models that are verified by component manufacturers, try using the electronics search engine features in Ultra Librarian. If you’re inspecting a design and you need to identify electronic components, you’ll be able to access verified distributor data and CAD data supplied by manufacturers to update your designs. All CAD data is compatible with popular ECAD applications and will help you streamline your verification process.

Working with Ultra Librarian sets up your team for success to ensure streamlined and error-free design, production, and sourcing. Register today for free.


The Ultra Librarian Team

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