Integrated passive devices
Integrated passive devices (IPDs), also known as integrated passive components (IPCs) or embedded passive components (EPC), are electronic components where resistors (R), capacitors (C), inductors (L)/coils/chokes, microstriplines, impedance matching elements, baluns or any combinations of them are integrated in the same package or on the same substrate. Sometimes integrated passives can also be called as embedded passives, and still the difference between integrated and embedded passives is technically unclear. In both cases passives are realized in between dielectric layers or on the same substrate. The earliest form of IPDs are resistor, capacitor, resistor-capacitor (RC) or resistor-capacitor-coil/inductor (RCL) networks. Passive transformers can also be realised as integrated passive devices like by putting two coils on top of each other separated by a thin dielectric layer. Sometimes diodes (PN, PIN, zener etc.) can be integrated on the same substrate with integrated passives specifically if the substrate is silicon or some other semiconductor like gallium arsenide (GaAs). Integrated passive devices can be packaged, bare dies/chips or even stacked (assembled on top of some other bare die/chip) in a third dimension (3D) with active integrated circuits or other IPDs in an electronic system assembly. Typical packages for integrated passives are SIL (Standard In Line), SIP or any other packages (like DIL, DIP, QFN, chip-scale package/CSP, wafer level package/WLP etc.) used in electronic packaging. Integrated passives can also act as a module substrate, and therefore be part of a hybrid module, multi-chip module or chiplet module/implementation. The substrate for IPDs can be rigid like ceramic (aluminumoxide/alumina), layered ceramic (low temperature co-fired ceramic/LTCC, high temperature co-fired ceramic/HTCC), glass, and silicon coated with some dielectric layer like silicon dioxide. The substrate can be also flexible like laminate e. g. a package interposer (called as an active interposer), FR4 or similar, Kapton or any other suitable polyimide.
