Dedicated high speed board materials such as Thermoset Hydrocarbon and PTFE laminates, will have better and more reliable properties in higher frequency designs than FR-4. There some trade-offs, which we will discuss shortly, but first let’s look at some of the advantages that high speed board design materials offer:To get more news about fr4 board, you can visit pcbmake official website.
Decreased Signal Loss. As transmission line frequencies increase, signal loss becomes more of a problem. High speed design board materials have a much lower dissipation factor than FR-4, with some of the materials, such as the nearly pure PTFE laminates, being an order of magnitude better. These lower dissipation factors have are a huge factor in reducing signal loss.
More Tightly Controlled Impedance. Traditional PCB materials such as FR-4 do not offer as precise control over dielectric constants (Dk) as high speed board materials do. FR-4 Dk’s can vary +/- 10% or more while materials such as PTFE hold their Dk tolerance at +/- 2% or better.
Better Thermal Management. Some high speed design board materials such as Thermoset Hydrocarbon laminates have much better thermal conductivity than FR-4. If your design is going to dealing with thermal management issues, then these board materials are the ones to investigate.
Increased Moisture Absorption. Water has dielectric properties and even a small amount of moisture absorbed into a PCB with high frequency circuits can change the electrical performance of those circuits. While FR-4 can have a moisture absorption rating of nearly 50%, some of the PTFE materials are as low as 2% and should be considered to resolve this problem.
Robust Dimensional Stability. For a dense high speed design with tight tolerances, the need for dimensional stability increases. While FR-4 is known for its dimensional stability, it lacks the other advantages that the high speed materials offer. In this case, the Thermoset Hydrocarbon laminates might be a better choice.
There is a cost to all the advantages of high speed board materials, and the first one to consider is the actual cost. These materials are expensive, and that needs to be factored into your decision. Another issue to consider is that some of these materials are more difficult to work with during fabrication and assembly than the others. The nearly pure PTFE laminates for example, which offer tremendous electrical performance, require fabrication processes which are not standard.
There are many different high speed board materials to consider, and each of them has their strengths and weaknesses. Part of your decision process will be to weigh the pros and cons of each material. Some may give a better electrical performance while at the same time be more difficult to fabricate. Another may be a better choice to fabricate with, but you may lose some of the thermal advantages of the first choice.
High speed PCB designs require careful selection of board materials for their construction, and FR-4 may not be the best choice. Although FR-4 is being updated to work better in high speed applications, there are many other options to chose from. These guidelines should help you as you consider which materials are best for your design.