Reinforcement for high frequency copper clad laminates

Copper Clad Laminates (CCL) are the raw material at the core of the Printed Circuit Board (PCB) technology which is used in all electronic devices from the one closest to the users (computers, smartphones, IoT devices etc.) to the one more integrated into our digital infrastructure (Antennas, data centers, etc.). The CCL which the PCB are made of, are composed of a dielectric layer insulating electrically two copper foils that are often clad on both sides. In order to transform a CCL into a PCB, a copper circuit is drawn on both sides by removing copper in between circuitry lines through mechanical processing, chemical etching or laser engraving. As PCB designs are requested to handle more functions, their design become more complex. One way of increasing the capacity of a PCB is to stack several layers of circuitry, each of them coming from a single CCL, to create a 3D network of copper allowing multiple electronic components to be connected. 
As we have been progressing through the digital era, one of the main technological driver has been the increase in capacity and speed of transferred data. The massive investments in infrastructure and technologies have allowed us  to benefit from a reliable access to the internet and an increasing amount of accessible data. The next technological gap envisioned by the electronic industry is the dawn of high frequency 5G (also called 5G mm-wave) which is expected to perform at frequencies above 20GHz allowing higher and faster data transfer in busy areas. 5G mm-wave is also expected to providing a lower latency in signal transfer allowing higher reliability of automated systems for Industry 4.0 and autonomous cars for example.

The use of higher frequencies is challenging the nature of the materials used in PCB. Indeed, the higher the frequency the more sensible is the signal to its surrounding environment and therefore there is a need for higher-end CCL materials. Among the key elements that are driving the performance of a CCL in regards to reducing its impact on signal, is the composition of the dielectric layer insulating the two copper circuits on both sides from each other. The composite dielectric layer is made of three main elements: resin, fillers and reinforcements. The combination of these three materials aims at increasing the performance of a CCL in term of dielectric loss, characterizing the impact on the signal, and in term of managing the heat generated by the higher density of electronic devices used in complex PCB.

    Reinforcement for CCL

      The reinforcement used in CCL has to meet multiple challenges such as:

      • Providing mechanical resistance during use at operating temperature and under various environmental conditions
      • Be thin enough to allow PCB designers to stack multiple CCL layers to create complex circuitry
      • Display high level of homogeneity to prevent signal perturbations
      • Contribute to the control of thermal expansion of the dielectric layer and match the one of copper to prevent cracking in copper circuitry during operations

      And of course the reinforcement should contribute to the low impact on the high frequency signal which is characterized by the dielectric constant and the dielectric loss. Both of these properties are among the main benefits of using pure silica reinforcement as silica has the lowest dk and df among all inorganic materials.

      Our Quartzel® materials, made of pure fused silica, can help CCL manufacturers to ensure optimum performance in high-frequency devices. Our Quartzel® materials are proposed in two versions to meet the electronic industry needs: Lightweight non-woven veils and lightweight woven fabrics, both of which are super lightweight (down to 6g/m²), thin (down to 2.5mil), mechanically resistant and homogeneous. Contact us for more details on why and how to use Quartzel® reinforcement in CCL.

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