As the company’s R&D hub for millimeter-wave products, Mini-Circuits’ Deer Park Technology Center on Long Island is home to some of the world’s most accomplished RF engineers and technicians. The facility hosts a state-of-the-art high-frequency test lab and its own assembly line contained in its spacious Class 100k clean room. The growing line of products designed and built at Deer Park is among the most technically sophisticated in Mini-Circuits’ portfolio, and the related production functions are accordingly some of the most advanced in the company’s global manufacturing operations.
Millimeter-wave circuits (operating from roughly 30 GHz to 110 GHz) are something of a dark art in the canon of RF engineering. The physics of high-frequency signals makes them especially sensitive to package shape and size, physical distance between circuit elements, and other factors. Most products in Mini-Circuits’ portfolio are mounted onto printed circuit board material using conductive solder through a heating process called reflow. The devices produced at Deer Park, by contrast, are assembled using wirebonding, whereby an unpackaged semiconductor chip is connected to adjacent circuitry via near-microscopic wires and welds. The unique nature of these products and their assembly requires special handling in a controlled environment with sophisticated equipment and a highly skilled team. Deer Park has all of the above under one roof.
The high-frequency products originating from Deer Park are built using wirebonding to connect wires of almost microscopic dimensions to a semiconductor die.
“These assemblies are chip-and-wire technology, so there are a lot of specialized assembly tasks that take a lot of experience and a lot of time to master,” explains Director of Engineering, Michael Ciardullo, who heads the high-frequency product line. “Defects are not as easily caught in inspection; sometimes you have to see them on the bench when you’re testing. Having assembly and production test in-house, all in the same clean room, allows technicians to go back to the assemblers if there’s a defect or if rework or alignment are needed.”
Stringent environmental control prevents dust and particles in the air from contaminating exposed circuitry.
The strict requirement for environmental control is one of a few unique facets of the high-frequency product assembly process. Whereas surface-mount devices are typically encapsulated in a package made of plastic, ceramic, or similar material, the semiconductor die used in chip-and-wire assemblies are unpackaged and exposed to the air. Contamination by dust and other airborne particles can cause defects and even catastrophic failures in the finished product. The air handling system in the clean room combined with controlled entry and exit with appropriate protective gear keeps particulate count low and the risk of foreign object damage virtually nil.
Another distinctive feature of the Deer Park production cell is that the entire assembly process takes place on-location. Many Mini-Circuits products travel through multiple workstations and often multiple facilities on their journey from raw materials to finished goods in stock. The high-frequency devices originating from Deer Park go from kitting through assembly, inspection, test, casing, and back to final inspection inside the glass on the second floor of 161 East Industry Court. From there, they only have to go downstairs to stock in the warehouse.
The Deer Park operation produces an impressive variety of products designed by the high-frequency engineering team. These include amplifiers, bias tees, step attenuators, mixers, power detectors, switches, and others. But beyond its native product line, Deer Park production also serves as a resource to other groups in the engineering organization, including MMIC and LTCC. A dedicated, in-house assembly line with capabilities for die handling and micro-assembly provides the flexibility, speed and quality control required for low-volume, high-mix workloads, whether they’re supporting internal qualification runs or fulfilling customer requirements for smaller orders with fast turnaround times.
None of this happens without the highly skilled team members bringing the dream to life every day. Qualified professionals with relevant experience to drive a production operation for such specialized semiconductor-based devices are few and far between, and building the right team was essential to making the product line a reality. Ciardullo hired the first assembler in 2020 before the Technology Center had officially opened. At the time of writing, the production team has grown to comprise four assemblers, a kit puller, two technicians, and a quality inspector.
Chip and wire assembly is an extremely delicate process requiring steady hands and high attention to detail.
“Working under a microscope and attaching a wire that’s thinner than a hair on your head to a MMIC die that’s two mils thick, that’s a very delicate process,” explains Ciardullo. “You have to have very steady hands and high attention to detail. You need many years of experience to understand what’s required in the manufacturing process, what you should do and what you can’t do at high frequency. The team we’ve hired here are some of the best I’ve ever worked with.”
The hiring process for the Deer Park assembly team is accordingly unique and rigorous. In addition to the standard interview, assembler candidates are tested on their skills with a task to transfer a MMIC die from one package to another under a microscope without mishandling or damaging the part. Mercifully, they aren’t offered coffee until that part of the interview is over.
With a strong core team in place, as model adoption continues to grow, experienced staff can now train more junior hires to scale production with demand. “We still have plenty of room to expand,” says Ciardullo.