High frequency PCB Assembly
High frequency has progressively become one of the important development trends of modern electronic goods, thanks to the fast growth of electronic technology and the widespread use of wireless communication technology in many sectors. High-frequency signal transmission and high-speed digitization need the help of fine wires and consistent dielectric layer thinning, micro-holes, and buried/blind holes. Therefore, High-frequency PCB design technology has emerged as a significant study subject.
A particular circuit board having a high electromagnetic frequency is known as a high-frequency electronic circuit board. In general, a frequency greater than 1 GHz is considered high frequency. It is often employed in automobile anti-collision, satellite, radio, and other sectors because of its excellent physical characteristics, accuracy, and technological specifications.
A high-frequency PCB is a circuit board made on a copper board utilizing a specific manufacturing technique. The substrate material must have high electrical characteristics as well as chemical stability. Furthermore, when the power signal frequency in the substrate increases, the material loss requirements decrease, highlighting the necessity of high-frequency PCB. If you want to learn more about high-frequency PCB, then this article is for you.
Let’s begin with its features.
Features of High-Frequency PCB
- They have a lower and more stable Dielectric Constant (Dk) ranging from 2.1 to 5 to reduce signal latency. The greater the frequency transmission rate, the lower the Dk value.
- The dissipation factor should be underestimated since it affects the quality of the transmitted signal.
- There should be reduced estimation of water retention during precipitation and wet conditions because excessive estimation of water intake influences the dielectric steady and dissemination factor.
- High-frequency electronic circuits provide adequate impact endurance, heat resistance, chemical resistance, and peel-off resistance.
- The boards verify that the laminates have the same thermal expansion rate as the copper foil. So, when the temperature changes, the copper foil does not separate.
Materials used for HF circuit board
Special materials are required to achieve the high frequency produced by this type of PCB. There are a number of substrate materials that will support your high-frequency PCB design. They will vary depending on the signal rates needed and the circuit board’s application/environment.
When compared to specialized high-speed materials like Teflon, FR4 is the least costly, with Teflon being the most expensive. When signal speed exceeds 1.6ghz, however, FR-4 performance begins to deteriorate. Thus, when it comes to Dk, Df, water absorption, and environmental survival, newer generation substrates, Teflon, and flex circuits are the most excellent alternatives.
Newer generation substrates, Teflon, and Flex substrates are significantly better than standard FR-4 material if a printed circuit board demands a frequency greater than 10GHz.
Isola, Taconic, Rogers, Dupont, and Panasonic’s Megtron materials are the most popular high-speed substrate providers. These materials all have a lower Dk and a lower loss.
How to Pick a PCB Material?
The following are the primary factors to consider while selecting the suitable material:
Manufacturability:
For example, temperature performance, material lamination performance, CAF/heat resistance, mechanical toughness (reliability), and fire rating.
Product-Specific Characteristics:
Low loss, consistent Dk/Df parameters, low dispersion, limited fluctuation coefficient with frequency and environment, small tolerance of material thickness and glue content, low roughness copper foil should be considered if the trace is lengthy.
Furthermore, the high-speed circuit must be simulated early in the design process, with the simulation result serving as the design’s reference standard.
Applicability of Laws and Regulations:
Environmental restrictions in various nations, such as RoHS and halogen-free requirements, must be met by the material.
Cost Factors:
Examine the price sensitivity of items, whether they are consumer goods or applications in communications, medicine, industry, or the military.
Material Procurement Cycle:
Many high-frequency materials, like the widely used RO4350B, have a lengthy procurement cycle. Therefore, if you need to construct PCBs with high-frequency materials, start contacting PCB makers as soon as possible so that materials may be prepared ahead of time.
Operating Speed:
The operating speed of high-speed digital circuits is the most crucial consideration when choosing PCB materials. The lower the Df value of PCB material, the faster the circuit runs.
The following are examples of high-frequency PCB materials:
- TUC: Tu862, TU883, TU872SLK, TU933, etc.
- Panasonic: Megtron4, Megtron6, etc.
- Isola: FR408HR, IS620, IS680, etc.
- Rogers Rogers: RO4003, RO4350, RO3003, RO5880, etc.
- Arlon, Taconic
- Nelco: N4000-13, N4000-13EPSI, etc.
How to Create Controlled Impedance Transmission Lines?
It is critical to develop controlled impedance transmission lines to minimize signal loss. Microstrip and Stripline techniques are the two most popular methods for creating controlled impedance transmission lines.
Microstrip:
A trace on the top layer that comes with a ground plane below is referred to as a microstrip. However, calculating the impedance of microstrip is a little hard and complex since it depends on a number of parameters such as the relative permittivity of the board material, the thickness & breadth of the trace, and its height above the plane. Therefore, to obtain a better outcome, the ground plane should be closer to the upper layer.
Stripline:
A stripline is a printed circuit board transmission line trace surrounded by a dielectric material and hung between two ground plane layers.
Stripline outperforms microstrip in terms of containing EMI radiation inside the two planes.
Applications of High-Frequency PCBs
Following are some of the essential applications of High-Frequency PCBa
Applications in the Military:
This circuit board is found in a variety of military devices, including weapons and ammunition.
The use of this board in many weapons improves their safety.
Applications in Medicine
We cannot ignore the dominance of electronic devices in medical sciences. For example, PCBs are also utilized in medical devices such as X-rays and CT scans.
Choosing the Right high-frequency PCB Manufacturers
Here are five ways that will help you select the right high-frequency PCB manufacturers.
- Quality of product.
- Standards and Certifications
- PCB Pricing
- Industry Relevant Manufacturing experience
- Customer Support Service
Final Words
Now you know that there are numerous crucial elements of a High-Frequency board and the design process. We hope you can build a high-quality, High-Frequency PCB using the tips mentioned above.
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