One of the most frequent questions we get here at DigiKey is requests concerning calibration. Certificates of calibration, instructions for calibration, requests that we perform calibration prior to shipping a product to the customer - often for components that do not require calibration, or fundamentally cannot be calibrated. This stems in part from the idea in those unfamiliar with the ins and outs of electronics that because some electronics are calibrated, it necessarily follows that all electronics must be calibrated, and in part from occasionally overzealous manufacturing quality control standards that require extensive documentation that may or may not exist. How can you tell which of your products requires calibration, and which calibration requests are superfluous?
What Needs Calibration?
Generally, an electronic device only requires calibration if it interacts with the outside world, off the circuit board. They must also be capable of altering or tuning their output to accommodate calibration.
The purpose of calibration is to ensure a given electronic device is correctly reporting, recording, measuring, or otherwise reading whatever phenomenon it is designed to read, record, report, or measure. Passive components on the PCB that act solely to manipulate the flow of electricity through the system, such as resistors, capacitors, diodes and the like, cannot ever be calibrated. These products do not interact with phenomena outside their circuit, nor can their output be tuned or altered - they cannot be calibrated. This also applies to most ICs that have nothing to do with sensors - ICs are generally not going to require or be capable of calibration. If the component or device does not ‘see’ the outside world in some way, it shouldn’t require calibration.
Most integrated sensors also fall under this category, as they cannot alter or tune their output. Things like thermocouples, loop current sensors, and similar components are fixed once manufactured. Devices built using these sensors can be subject to calibration - the sensors themselves cannot. They are either within specification and thus usable, or outside of specification and not usable.
This can usually be extended to electronics as a whole. Equipment can be calibrated, components cannot be. The system as a whole can be calibrated, rather than its individual parts.
The vast majority of products that DigiKey offer do not require calibration. If it’s not a sensor, a measurement device, certain kinds of hand tools, or a piece of laboratory equipment such as a benchtop power supply , it probably doesn’t require calibration and won’t have calibration documentation available.
How Can You Tell For Sure?
Unfortunately there’s no 100% accurate rule for determining what does and does not require calibration, nor is calibration itself so simple as “buy calibrated part, profit.” Per our existing thread on Calibration and Calibration Certificates, calibration requirements different from product to product as well as project to project, and calibration is almost never permanent. You will need to recalibrate your equipment periodically after purchase; this generally cannot be avoided. Your calibration needs will be different than the calibration needs of a different customer, and your calibration needs will likely change between projects as well. The best way to figure this out is to ask your engineering team to determine what needs calibration, when, and how, and then follow their guidelines.