You Must Know When You Can Use FR4 to Design A PCB

Keywords: FR4 PCB  

 

The FR4 PCB is quite common. For some applications, particularly high-frequency ones, FR4 is not the best choice. High-frequency laminates are typically a more popular option for these patterns. Since selecting from among these options might be challenging, we have included additional specific instructions below. If you're attempting to select between using FR-4 or a high-frequency laminate to design a PCB, take into account the following critical characteristics of each.

 

The price of FR4 will be lower.

Because of its comparatively inexpensive cost, FR4 material is a highly popular PCB basis. On the other hand, high-frequency laminates are significantly more expensive, which is a big disadvantage for designers and manufacturers that are worried about costs. This is the main criterion that businesses use to decide between FR4 and high-frequency laminates.

 

Lower Df Causes Lower Signal Loss for Signal

In many circumstances, signal loss is a crucial component of a PCB design, particularly in high-frequency settings where signal loss is a bigger issue. Since FR4 has a larger Df, or dissipation factor, than high-frequency laminates, it is not the best material for these designs. Accordingly, FR4 circuits will experience greater signal loss than a comparable circuit built on a high-frequency laminate.

 

While most high-frequency laminates have a Df of roughly 0.004, or one-fourth of FR4's, FR4 has a Df of around 0.020. There is less total signal loss the lower the Df. The second problem is that when a signal's frequency rises, greater signal loss is experienced since the Df of FR4 increases. High-frequency laminates have less loss at higher frequencies because they have more consistent Df properties.

 

Impedance Stability: Dk Stability Matters

Another crucial consideration for many designs is stable impedance, which frequently translates into more predictable performance, particularly for bigger circuits or high-frequency designs. Again, FR4 and high-frequency laminates provide distinct outcomes in this region. To maintain stable impedance, a material must maintain a constant Dk, or dielectric constant, throughout the material while its temperature changes.

 

Due to its Dk value's significant variation both within a single board and when the board's temperature changes, FR4 is not a material that is suited for maintaining stable impedance in this respect. The Dk values of high-frequency laminates don't vary as much and stay largely consistent throughout a board as temperature changes. However, the FR4 PCB is in high demand.