PCB Technology

What is High Frequency PCB

What is HIGH FREQUENCY PCBs (printed circuit boards)?

High Frequency PCBs

Oneseine is a professional High frequency pcb manufacture

Due to the long-standing, close co-operation with our material suppliers (Rogers, Taconic, Neltec, etc.), we are able to offer you a unique package for your HF- application. Our engineering team with trained antenna developers will support you in the selection of suitable substrates, in the construction or the PCB design.

10 years' experience in the manufacture of high-frequency circuit boards has made us the leading manufacturer of this technology. Embedded heatsinks, multilayer circuits from pure Teflon (PTFE material),Rogers PCB material, manufactured using fusion-bonding or designs with mixed materials (FR4 and PTFE), have become standard technologies for VARIOPRINT, and are carried out in large numbers and with stable and controlled process parameters every day.

Electronic devices with high frequency is the developing tendency nowadays, especially in wireless network. Satellite communication growing rapidly, information products move towards high speed and high frequency. Thus developing new products always need to use high frequency substrate, satellite system, mobile telephone receiving base station and so on, these communication products must use high frequency PCB.

The features of high frequency PCB as following:

1. DK should be small and stable enough, usually the smaller the better, high DK may lead to signal transmission delay.

2. DF should be small, which mainly affect quality of signal transmission, the smaller DF could make smaller signal wastage accordingly.

3. The thermal expansivity should be the same with copper foil as much as possible, because the difference will lead to copper foil separated in the changes of cold and heat.

4. Water absorptivity must be low, high water absorptivity will affect DK and DF when in the wet environment.

5. Heat resisting property, chemistry resisting, impact endurance, peel off resisting must be good.

Generally speaking, high frequency can be defined as frequency above 1GHz. Currently, polyfluortetraethylene(PTFE) material is widely used in high frequency PCB manufacturing, it's also called Teflon, which frequency is normally above 5GHz. In addition, FR4 or PPO substrate can be used to the product frequency among 1GHz~10GHz. These three high frequency substrate have below differences:
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With regard to laminate cost of FR4, PPO and Teflon, FR4 is the cheapest one, while Teflon is the most expensive one. In terms of DK, DF, water absorption and frequency feature, Teflon is the best. When product application require frequency above 10GHz, only can we choose Teflon PCB substrate to manufacture. Obviously, the performance of Teflon is far better than other substrate, However, Teflon substrate has the disadvantage of high cost and large heat resisting property. In order to improve PTFE stiffness and heat resisting property function, a large number of SiO2 or fiber glass as the filling material. On the other hand, due to molecule inertia of PTFE material, which it is not easy to combine with copper foil, thus, it needs to do special surface treatment on the combination side. With regard to combination surface treatment, normally use chemical etching on PTFE surface or plasma etching to plus surface roughness or add one adhesive film between PTFE and copper foil, but these may have influence on dielectric performance.
RF - Radio Frequency PCBs

Radio-frequency (RF) and microwave (MW) circuits can be found in countless wireless products from handheld devices for medical and industrial applications to advanced communications systems for base stations, radar and global positioning. The success of these high-speed products begins at the product design stage when the PCB laminate materials are selected. Oneseine works with the product design team to insure that the project’s cost/performance targets can be met by providing information on material options, relative costs and DfM considerations. Once the design has been completed, Oneseine follows the boards from prototype through to production where key process variables such as line widths and dielectric spacing are measured and controlled to insure the product meets the designed requirements and delivers consistent performance throughout the products life cycle.

The high-frequency pcb circuit board includes a core board with a hollow groove and a copper-clad board bonded to the upper and lower surfaces of the core board through flow adhesive. The upper and lower opening edges of the hollow groove are provided with blocking edges.
High frequency pcb circuit board is a special type of circuit board with high electromagnetic frequency. Generally speaking, high frequency can be defined as a frequency above 1GHz. Its various physical properties, accuracy, and technical parameters require very high requirements, and are commonly used in fields such as automotive collision prevention systems, satellite systems, and radio systems.
The high-frequency pcb circuit board provided by the utility model is equipped with blocking edges that can block the flow of adhesive at the upper and lower opening edges of the hollow groove of the core board. In this way, when the core board is bonded with the copper clad board placed on its upper and lower surfaces, the flow of adhesive will not enter the hollow groove, and the bonding operation can be completed with one press. Compared with the high-frequency circuit board that requires two presses in existing technologies to complete, the high-frequency circuit board in the utility model has a simple structure, low cost, and is easy to manufacture

How to design a PCB for high frequency?

I.Introduction
High-frequency PCBs, often called R.F. (Radio Frequency), are a specialized category of printed circuit boards designed to handle signals with frequencies in the gigahertz range. These boards are critical in various applications, from wireless communication devices to radar systems and medical equipment. In this article, we will delve into the intricacies of high-frequency PCB design, highlighting the significance of proper design techniques and providing a comprehensive overview of the topics we will cover.

High-frequency PCBs are engineered to accommodate signals that operate at significantly higher frequencies than standard PCBs. These frequencies typically fall in the range of 1 GHz (gigahertz) and above. Due to their unique characteristics and the demands of high-frequency applications, these PCBs differ in design and material selection compared to their lower-frequency counterparts.

Selecting the Right Materials for High-Frequency PCBs
When designing high-frequency PCBs, one of the foundational decisions you'll face is selecting the suitable materials.

A.Overview of PCB Material Options
PCBs can be fabricated using various materials, each with its characteristics. Here are some standard options:

1.FR-4 (Fire-Resistant 4):

· FR-4 is a widely used PCB material due to its affordability and versatility.

· It is suitable for low to moderate-frequency applications but may not be ideal for high-frequency PCBs due to its limitations in terms of dielectric properties.

2. Rogers Corporation Materials:

· Rogers Corporation produces a range of high-frequency PCB materials, such as the RO4000 series and RO3000 series.

· These materials are engineered specifically for high-frequency applications, offering low dielectric loss and consistent performance.

3. PTFE (Polytetrafluoroethylene):

· PTFE-based materials like Teflon are known for their excellent electrical properties and low loss characteristics.

· They are well-suited for high-frequency PCBs, particularly in applications where signal integrity is critical.

4. Isola Materials:

· Isola manufactures materials like IS620 and IS680 for high-speed and high-frequency applications.

· These materials provide low loss and stable dielectric constants.

Designing a high-frequency PCB correctly is of paramount importance for several reasons:

1. Signal Integrity
High-frequency signals are susceptible to various forms of interference and degradation. Proper PCB design minimizes signal losses, reflections, and electromagnetic interference (EMI), ensuring reliable signal transmission.

2. Impedance Matching
Impedance matching is crucial in high-frequency circuits to prevent signal reflections. A well-designed PCB maintains consistent impedance across traces and components.

3. Minimized Crosstalk
Crosstalk between traces can lead to signal distortion. Careful design techniques help minimize Crosstalk, preserving signal quality.

4. EMI/EMC Compliance
High-frequency devices must adhere to electromagnetic interference (EMI) and electromagnetic compatibility (EMC) regulations. Correct PCB design aids in achieving compliance.

5. Heat Dissipation
High-frequency components generate heat. Effective thermal management is necessary to prevent overheating and ensure long-term reliability.

In the following sections, we will delve deeper into the intricacies of high-frequency PCB design. We will explore critical aspects such as selecting suitable materials, designing the layer stack up, component placement, grounding strategies, impedance matching techniques, signal integrity analysis, and considerations for electromagnetic compatibility (EMC) and electromagnetic interference (EMI). Additionally, we will discuss the importance of testing and validation in high-frequency PCB design.