PCB Material and Laminate Selection for Fabrication
This presentation will discuss efficient PCB material selection. Before selecting begins, there are many factors to consider. Make sure material characteristics fit your specific board requirements and end application. Today, we will focus on the dielectric properties, cost, and manufacturability of materials suitable for high-speed PCB designs .
One of the main problems we face when manufacturing PCBs is the PCB designers’ frequent over-reliance on the material datasheets. Don’t get me wrong, data sheets provide designers with a thorough description of a material’s electrical properties, and electrical properties are the primary consideration for high-speed applications. However, the data sheets fall short when taking into account various real-world manufacturing concerns, and real-world manufacturing concerns matter because they impact yield and cost.
How do I choose a PCB material?
5 Basic PCB Material Categories
Regarding PCB material selection for high-speed PCBs, what are the primary concerns that must be concerned in regards to one, manufacturability, and two, cost? Let’s take a look at this chart. For convenience, we’ve classified important materials into buckets based on the material’s signal loss properties.
On the left, we have materials like FR-4. These are your standard, everyday materials, such as materials from China like Nan Ya, and materials from the US, like Isola. FR-4 are standard materials that can be used in any application, but they are also the lossiest laminates. It can also have a plethora of other electrical and mechanical issues, and if you’re having issues with FR-4 material, shoot me an email. I would love to help.
As we move across the chart, you can see the less lossy, higher speed application PCB materials. Rogers 4350 performs similarly to Megtron 6 and Itera, so these are the materials you should consider when you need that level of performance.
How to choose PCB laminates?
PCB material selection depends upon various characteristics of the dielectric material used. These properties include :
Glass transition temperature (Tg) – the temperature at which the material transforms from a solid state to a viscous state is called glass transition temperature. This is a critical parameter for PCB material selection.
Thermal decomposition temperature (Td) – the temperature at which the material decomposes chemically is called thermal decomposition temperature.
Dielectric constant (Dk) – the speed at which an electrical signal travels in the dielectric medium is called the dielectric constant. This is a critical parameter for PCB material selection.
Loss tangent (tanδ) – the power loss of a signal as it passes through a transmission line on a dielectric material is called the loss tangent.
Coefficient of Thermal Expansion (CTE) – the change in dimensions of a material as a response to a change in...
