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Higher-Order Filters
Published in John T. Taylor, Qiuting Huang, CRC Handbook of ELECTRICAL FILTERS, 2020
F. William Stephenson, William B. Kuhn
The performance of passive components used in the filter is critical in achieving the desired transfer function. The most obvious performance parameters to consider include resistor and capacitor tolerances, but other parameters, such as temperature coefficient, effects of aging, humidity, and soldering heat, should be taken into account. For demanding applications laser trimming of resistors can also be used. Trimming procedures may be either deterministic (or passive) in which the value of individual resistors is adjusted before applying power to the circuit, or functional in which the resistors are trimmed in operation to yield the desired response characteristic. A combination of deterministic trimming followed by functional trimming may be used to reduce the problem complexity and number of iterations required. Table 3 lists representative performance parameters for a variety of common resistor types.
Components and Devices
Published in Katsuyuki Sakuma, Krzysztof Iniewski, Flexible, Wearable, and Stretchable Electronics, 2020
For many applications, the precision of the resistance value of the resistor is important. This presents a problem for printed resistors, which may have a tolerance of ±20% or more [8]. Post-processing may be required if precise resistor values are necessary. This is commonly achieved using laser trimming, wherein over-sized (with correspondingly lower resistance) devices are fabricated and laser ablation is used to selectively remove material until the resistance is raised to the desired level [9]. The poor tolerance of printed resistors is due to many factors, such as inherent variability in the printing process and ink evolution during processing. Process variation can be minimised in design where possible, such as increasing component dimensions to minimise variation due to line width variation. Component matching to minimise process variation may also be required, depending on the circuit requirements [8].
Hybrid Microelectronics Technology
Published in Jerry C. Whitaker, Electronic Systems Maintenance Handbook, 2017
One of the advantages of the hybrid technology over other packaging technologies is the ability to adjust the value of resistors to a more precise value by a process called trimming. By removing a portion of the resistor with a laser or by abrasion, as shown in Fig. 11.5, the value can be increased from the as-processed state to a predetermined value. The laser trimming process can be highly automated and can trim a resistor to a tolerance of better than 1% in less than a second.
Design and validation of a gripper for the automated assembly of film components in flexible electronics manufacturing
Published in International Journal of Computer Integrated Manufacturing, 2023
Marcello Valori, Vito Basile, Gianmauro Fontana, Jose A. Mulet Alberola, Serena Ruggeri, Simone Pio Negri, Irene Fassi
The manual assembly of coverlay films on FPCB layers is performed by specialized operators in a clean room maintained at specified conditions of temperature (20–25°C) and humidity (relative humidity in the range of 40–60%). Operators must wear overalls, hair cap, gloves and face mask to prevent contamination of dust, airborne organisms and particulates, vaporized particles, and so on. The commercial material sheets are obtained from coils, representing the original supply format; the single coverlays are then cut by laser-trimming, in compliance with the FPCB design. After the removal of the protective film, the coverlay is accurately placed onto the FPCB. Various welding spots are then applied for temporary bonding; the acrylic adhesive resin is then activated by thermo-mechanical curing, before the final lamination of the stack-up (Cui 2016).