Thin Film Integrated Passive Devices
The specifications of the end product (e.g., price, size, and reliability) determine which passive components will best serve the design, so the market is dense with options. Integrated passive devices (IPD) represent a category of components designed for optimal, application-specific use rather than general use. IPDs emerged in the 1960s as a solution for reducing the total number of assembly steps in the circuit manufacturing process. To this day, leveraging IPDs is an effective approach for engineers working to meet size, weight, and power (SWaP) goals.
Ranging in complexity, IPDs combine circuit building blocks (e.g., conductors, resistors, vias, traces, bridges, etc.) in one single device. While this presents manufacturing benefits, condensed components can create performance issues if improperly assembled.
The most common processes for IPD manufacturing are thick film and thin film construction. Manufacturers have leveraged thick film technology since the 1950s, but thin film technology is gaining popularity in some markets because of its process precision and tight integration. IPD construction can extend product assembly time, but with the added benefits of thin-film technology, high performance tends to outweigh potential timing concerns.
With all this in mind, the build-to-print approach is a valuable strategy for IPD development. Relatively speaking, PCBs take up a lot of space, and building IPDs with thin film allows designers to safely place several connections close together without compromising placement accuracy. Thick film technology has a long history of reliability, but it’s not as accurate for small-scale construction.
With IPDs constructed with thin film technology, there’s a single, optimally functional component placed in the end device rather than dozens of capacitors and resistors. Designers can use the extra space for other components or miniaturize the entire design.
Typical use cases for IPDs include:
- Custom resistor-capacitor networks
- Lange couplers and power combiners
- EMI filters
- High-frequency filters
- Microwave integrated circuits
- Bias decoupling and filtering
- Lumped element impedance matching networks
- PA stabilizations
- Impedance matching and power combining networks
