Laser Trimming of Resistors
After firing, the substrate resistors are trimmed to the correct value. This process is named Laser trimming. Many chip resistors are made using thick film technology. Large substrates are printed with resistors fired, divided into small chips and these are then terminated, so they can be soldered on the PCB board. With laser trimming two modes are used; either passive trimming, where each resistor is trimmed to a specific value and tolerance, or active trimming, where the feedback is used to adjust to a specific voltage, frequency or response by laser trimming the resistors on the circuit while powered up.
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