The increasing complexity of electronic components and switches continually requires faster signal flow rates, and thus higher transmission frequencies. Because of short pulse rise times in electronic components, it has also become necessary for high frequency (HF) technology to view conductor widths as an electronic component.
Depending on various parameters, HF signals are reflected on circuit board, meaning that the impedance (dynamic resistance) varies with respect to the sending component. To prevent such capacitive effects, all parameters must be exactly specified, and implemented with the highest level of process control.
Critical for the impedances in high frequency circuit boards are principally the conductor trace geometry, the layer buildup, and the dielectric constant (εr) of the materials used.
Multi-CB provides you with know-how, all popular materials and qualified manufacturing processes - reliably even for complex requirements.
Materials used for HF circuit boards
High-frequency boards, e.g. for wireless applications and data rates in the upper GHz range have special demands on the material used:
- Adapted permittivity
- Low attenuation for efficient signal transmission
- Homogeneous construction with low tolerances in insulation thickness and dielectric constant
For many applications, it is sufficient to use FR4 material with an appropriate layer buildup. In addition, we process high-frequency materials with improved dielectric properties. These have a very low loss factor, a low dielectric constant, and are primarily temperature and frequency independent.
Additional favourable properties are high glass transition temperature, an excellent thermal durability, and very low hydrophilic rate.
We use (among others) Rogers or PTFE materials (for example, Teflon from DuPont) for impedance controlled high frequency circuit boards. Sandwich buildups for material combinations are also possible.
| Material for high frequency boards | Order share | εr, Dk- Permittivity | Dk Loss Tangent | Tg | Td Value | Thermal conductivity | CTE-z (T < TG) | Electric Strength | Surface Resistivity | Peel Strength |
|---|---|---|---|---|---|---|---|---|---|---|
| @10GHz | @10GHz | °C | °C | W/m*K | ppm/°C | KV/mm | MΩ | N/mm | ||
| Rogers 4350B HF Material | +++ | 3,5 | 0,0037 | 280° | 390° | 0,69 | 32 | 31 | 5,7 x 10^9 | 0,9 |
| Rogers 4003C PTFE HF Material | ++ | 3,4 | 0,0027 | 280° | 425° | 0,71 | 46 | 31 | 4,2 x 10^9 | 1,1 |
| Panasonic Megtron6 HF Material | + | 3,6 | 0,004 | 185° | 410° | - | 45 | - | 1 x 10^8 | 0,8 |
| Rogers RO3003 PTFE ceramic-filled | + | 3,0 | 0,0013 | - | 500° | 0,50 | 25 | - | 1 x 10^7 | 2,2 |
| Rogers RO3006 PTFE ceramic-filled | o | 6,2 | 0,002 | - | 500° | 0,79 | 24 | - | 1 x 10^5 | 1,2 |
| Rogers RO3010 PTFE ceramic-filled | o | 10 | 0,0022 | - | 500° | 0,95 | 16 | - | 1 x 10^5 | 1,6 |
| Taconic RF-35 Ceramic | o | 3,5** | 0,0018* | 315° | - | 0,24 | 64 | - | 1,5 x 10^8 | 1,8 |
| Taconic TLX PTFE | o | 2,5 | 0,0019 | - | - | 0,19 | 135 | - | 1 x 10^7 | 2,1 |
| Rogers RO3001 Bonding Film for PTFE | - | 2,3 | 0,003 | 160° | - | 0,22 | - | 98 | 1 x 10^9 | 2,1 |
| Taconic TLC PTFE | - | 3,2 | - | - | - | 0,24 | 70 | - | 1 x 10^7 | 2,1 |
Complete overview of available circuit board materials
Depending on the stock on hand, the materials listed may be replaced by technically equivalent or similar products. For critical tolerances, please discuss your requirements with our engineers.
Impedance Check
The impedance defined by the customer is tested by our CAM station engineers on manufacturability. Depending on the layer buildup, the PCB layout and the customer's requested impedances a calculation model is chosen. The result is any required modification of the layer builduo and the necessary adjustments to the relevant conductor geometries.
Please also refer to our pages for impedance control of printed circuit boards.
After the manufacture of high frequency circuit boards, the impedances are checked (with a precision of up to 5%), and the detailed results are recorded exactly in a test protocol.