The objective of RF packaging—where RF (radio frequency) is the range of electromagnetic frequencies above the audio range and below infrared light (from 10kHz to 300GHz)—is to transfer signals while preserving bandwidth (Tummala). This becomes more challenging at higher frequencies because of the wave nature of RF signals. The applications of personal communication, wireless local area networks, satellite communications and automotive electronics are providing the driving force for packaging needs at higher frequencies, motivating manufacturers to provide lower cost technology solutions with increasingly higher performance and functionality. In addition, there is a driving force for new products to provide the same functionality at a smaller overall size, lower power and better design (Zhang, Lec 1).
Why are these attributes important? Take RF power for example, which is the primary measure of a wireless signal. In a receiver, signal strength is a key factor in maintaining reliable communications. In the transmitter, the amount of power transmitted is important for maintaining the range and reliability of the radio link.
Automation
It has been the experience in the lab at Palomar Assembly ServciesTM ("Assembly Services"), in that automating the RF packaging process, even at the ever increasing levels of complexity and minaturization, is possible. Once the process is set up, a single operator can build the needed packages in a cost-effective manner. The operator works with three or four systems at time: high-accuracy wire bonder, a flexible and accurate die bonder and an additional high-accuracy die bonder (with an optional configuration for wafer scale packaging). If there is a need for an automated precision dispenser, that too can be added to the mix. (right: wire bonder performing complex low loops that are often used in RF packaging).
Evolution
Wireless technologies have evolved rapidly over the past two decades. Previously, large RF/microwave modules have begun to evolve into multi-function systems such as system-on-a-chip (SoC) and sytstem-in-a-package (SiP) methodologies. Many industries are utilizing these technologies. For example, the medical industry is using RF functionalities for pacemakers and other implantable devices. The aerospace and defense industries are creating new communication, surveillance and anti-jamming technologies for the modern battlefield. And industrial RF application developers are improving the real-time monitoring of field and factory operations. (Ebbutt)
Trends
There are several trends occurring in RF packaging. The first is variation in levels of integration: an integrated package solution provides a reasonable time-to-market with good yield, while a fully integrated solution takes a longer time to go to market. Second is to integrate passive components: there has been a decrease in passive components and a move to multilayer devices. Third is to integrate the RF substrate: the RF substrate is moving towards a modular design with integrated components. Finally, there is an increasing trend for RF MEMS as the demand exists for smaller and smaller devices.
Learn more: Wire Bonding an RF-SOE Package using a Gold Ball Bonder
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Jessica Sylvester
Marketing Communications
Palomar Technologies
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References
Allen, Roger. Shrinking ICs Need High Density In A Package Deal. July 24, 2008. http://electronicdesign.com/Articles/Index.cfm?ArticleID=19340
Ebbutt, Ralph. Electronic Packaging RF SiPs Demand Early Packaging Focus. 2009. http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0032119&ISSUE=0904&RELTYPE=ic&PRODCODE=O0160&PRODLETT=A&CommonCount=0
Tummala, Rao R., Chapman, Steve. Fundamentals of Microsystems Packaging. 2001. http://books.google.com/books?id=P93ZrOWHlO0C&pg=PA534&lpg=PA534&dq=history+rf+packaging&source=bl&ots=rjmKkSb5zT&sig=BxEbGFb8N7aH0Ije5eYJ2OWiiiE&hl=en&ei=ArZCSr_bOoXYtgPxi43MDw&sa=X&oi=book_result&ct=result&resnum=3.
Zheng, Li-Rong. Lecture 1: Evolution of Electronic Systems from Chips to Cabinets. http://www.ict.kth.se/courses/IL2208/Lectures/ESP_Lect1.pdf