What is Thermal Coefficient of DK in High Frequency PCB?

January 14, 2025

1.Definition and Importance of DK Thermal Coefficient

The DK thermal coefficient refers to the change in the dielectric constant of high-frequency PCB materials with temperature. It plays a crucial role in the performance of high-frequency PCBs, serving as a bridge connecting technology and innovation in the electronics world. Understanding the importance of the DK thermal coefficient is akin to finding the key to unlocking exceptional performance.

2. Relationship Between High-Frequency PCB Performance and DK Thermal Coefficient

The performance of high-frequency PCB hinges on signal transmission stability and efficiency. The DK thermal coefficient is directly related to thermal stability. A lower DK thermal coefficient allows the PCB to maintain a relatively stable dielectric constant during temperature fluctuations, ensuring uninterrupted signal transmission. Conversely, a higher DK thermal coefficient can lead to signal degradation and distortion.

3.DK Thermal Coefficient vs. Temperature Graph

The two tables below illustrates the changes in the DK thermal coefficient at varying temperatures for Taconic, Rogers, and Wangling materials, offering a clear comparison of their performance stability in high-frequency PCB applications.

3-1.DK Value Comparison Table

Notes:

(1).Taconic Material : Shows slight increases in DK values at high temperatures, indicating stability under temperature changes.

(2).Rogers Material: Maintains small DK value changes across temperatures, showcasing good thermal stability ideal for high-frequency applications.

(3).Wangling Material: Exhibits controllable DK values similar to Taconic and Rogers, suitable for various frequency and temperature conditions.

4. Features of Leading high-frequency Material Suppliers

4.1 Taconic

Taconic materials exhibit excellent DK thermal coefficient performance. Their materials maintain a low DK thermal coefficient, allowing for a stable dielectric constant under varying temperatures. This characteristic ensures stable and efficient signal transmission in high-frequency communication and radar systems.

4.2 Rogers

Rogers materials are known for their effective control of the DK thermal coefficient. With minimal changes across a wide temperature range, Rogers materials significantly reduce signal transmission issues related to temperature fluctuations, making them suitable for high-performance microwave and RF applications.

4-1. Schematic diagram of Rogers high-frequency PCB's DK value varying with temperature

Based on the data comparison, we will find that Rogers RO3003 exhibits an exceptionally stable dielectric constant thermal coefficient. This stability, combined with consistent mechanical properties, allows designers to create multi-layer board designs without encountering issues such as warpage or reliability concerns.

4.2.1 The introduction of Rogers RO3003

*Material Composition

Rogers RO3003 is a high-frequency circuit material made from ceramic-filled PTFE composites.

*Circuit Board Specifications

The 2-layer Rogers 3003 10mil circuit board features:
Dielectric Constant (DK): 3.0
Dissipation Factor (DF): 0.001

*Thermal Expansion Properties

Coefficient of Thermal Expansion (CTE):
X and Y Axes: 17 ppm/℃
Z Axis: 24 ppm/℃

*Etching Characteristics

Etch Shrinkage: Typical shrinkage is less than 0.5 mils per inch after the etch and bake process.

*Reliability

The surface finish on the pads and exposed traces is chemical gold, which enables excellent performance for surface-mount device (SMD) soldering. Besides, the entire board is covered by a green solder mask, providing protection and enhancing durability.

*Application

A wide range of microwave and RF applications.

4-2. Rogers RO3003 high frequency PCB Substrate

4.3 Wangling

Wangling materials also demonstrate competitive DK thermal coefficients. Through innovative technology and strict quality control, Wangling offers materials with controllable DK thermal coefficients, providing stable performance for high-frequency circuits across various frequencies and temperatures.

4.4 Summary of CPB Material

The following table summarizes the key features of Taconic, Rogers, and Wangling material.

5. Concluding Remarks

“In the vast universe of high-frequency PCBs, the DK thermal coefficient is the shining star, guiding the development of the electronics industry.” Whether in communication devices, aerospace, or medical electronics, selecting appropriate PCB materials and closely monitoring the DK thermal coefficient is crucial for optimizing design and enhancing quality.