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AUGUST 2018 I DESIGN007 MAGAZINE 45 by the frequency and rise time of the digital signal with lower values of loss most suitable for high-frequency applications. These materi- als generally exhibit lower values of dielectric constant resulting in faster signal propagation. Figure 1 depicts the profile for dielectric materials with a Df < 0.005. The iCD Mate- rials Planner has five default profiles ranging from basic FR-4 to ultralow-loss materials as in Table 1. This enables the designer to compare dielectric materials based on manufacturer, fabricator, frequency, dissipation factor (loss) and dielectric constant. The other issue is that different materials are available locally compared to off-shore and also vary from fabricator to fabricator. Typically, prototype boards are fabricated locally, whereas Asia is a more economical option for mass pro- duction. A profile for each PCB fabricator that you usually deal with can be set up. This will display the complete range of materials that each Fab shop stocks. This also enables the compari- son of competitive fab shop capabilities. Figure 2 plots the loss properties of dielectric materials from an Asian fabricator. One can easily see which materials are best for high- speed applications and can choose a few mate- rials from this that are in stock. Cost-to-perfor- mance evaluations must still be done to ensure the lowest cost material, that will do the job, is selected. Also, keep in mind that material costs vary with quantity. Figure 2: Example of a fabricator's dielectric materials loss profile. Table 1: Loss profile ranges for various materials.