High-Frequency PCB Manufacturer

Over the past decades, the demand for faster computing and higher data throughput has increased signal speeds by magnitudes. Unfortunately, faster speeds reveal performance issues with design, materials, and manufacturing that are trivial at relatively slower speeds. High-frequency PCB manufacturers can use several methods to navigate these issues while optimizing cost and performance. At VSE, options for flexible printed circuits, cable harnesses, wire assembly, and overall box-build solutions can further reduce insertion loss to promote high-frequency signal integrity.

Comparing Low- and High-Frequency Board Materials

How Board Materials Respond to High Speeds

A high-frequency PCB manufacturer will help guide designers through production when cutting-edge performance is essential to design intent. One of the foremost challenges when manufacturing high-frequency PCBs is accounting for the skin effect; at high speeds, the current density concentrates toward the conductor’s surface as a function of frequency. This concentration affects the conductor’s impedance profile and can produce current crowding/choking that undermines performance and potentially damages the board.

To navigate the skin effect, high-speed laminates on the bonding side of the conductor use low-profile copper teeth that reduce the surface path length at high speeds. However, a byproduct of the reduced copper roughness on the conductor’s bonding side means a lower peel strength between the substrate and the conductor. Combined with specific substrates (e.g., PTFE AKA “Teflon”), the lower peel strength may result in greater delamination defects during soldering that imperil board yield. FR-4 has worse high-frequency characteristics than PTFE, but its hardier performance during manufacturing improves its overall viability. Different substrate constructions can also counter some of the inherent high-frequency disadvantages of FR-4, namely the nonhomogeneity and anisotropy:

• Nonhomogeneity – FR-4 and similar laminates use epoxy resin impregnated with glass fibers for structural rigidity. The electrical properties differ significantly (e.g., the resin’s dielectric constant is less than that of the glass fibers).
• Anisotropy – The material properties of PCB substrates change depending on the orientation of the design element. For example, a trace that runs parallel above a glass fiber and a trace that runs perpendicular to glass fiber(s).

How High-Frequency PCB Manufacturers Adapt Processes

Standard processes of PCB fabrication manufacturers wouldn’t otherwise bat an eye at can become significant detriments to high-frequency performance. Take the solder mask layer, for example: solder mask provides an electrically insulative and protective barrier that prevents shorting between circuits. However, the addition of the solder mask affects the dielectric background of the transmission (i.e., substituting the solder mask for atmosphere increases the dielectric constant on the outer-facing side of the copper). At low frequencies, the difference in the dielectric constant is so minute to be negligible but can become considerable at high frequencies – at 20 GHz, the insertion loss is ~0.1 dB/in. In terms of waveform characteristics, the addition of the solder mask shifts the center frequency leftward, reduces the Q-factor, and narrows the bandwidth.

One method to tamp down further insertion loss is to minimize the number of discrete connectors; one method to accomplish this reduction is with flexible printed circuits. Flexible printed circuits alone or as part of rigid-flex system integration can bundle multiple wires in an arrangement that is far more amenable to saving space within an enclosure. VSE is an expert in box-build assemblies: by carefully considering your unique constraints, we can craft a single-stop, all-inclusive electronic manufacturing that balances the unique performance requirements of high-speed designs.

Your Contract Manufacturer for High-Frequency Designs

By partnering with an experienced high-frequency PCB manufacturer like VSE, designers can be confident that their high-frequency PCBs will be up to spec. VSE handles all kinds of electronic requests; in addition to PCBs and flexible printed circuits, it can also fulfill wire harnesses, cable assemblies, enclosures, test fixtures, and box-build manufacturing solutions. Our engineers are committed to building electronics for our customers, and for over forty years, we’ve been partnering with design teams to realize devices that change and save lives.