PCB (FR4) material properties

Hello all!

How to create FR4 fiberglass material commonly used for PCB production?
There is some “epoxy” in Material database (probably can be used as 1st component), and for 2nd component should be used fiberglass. I found it is fraction of 70-78% (of FR4 mass) but not sure because there are lots of variants.
The next part, what is its correct physical properties: dE/dx and etc?

Best regards,

Hello Dmitrii,

Please find here an input file with an example implementation of FR4 material: PCB_material.inp (4.5 KB).

Please note the following:

  1. The choice of which material is completely up to you and you should cross-check that it is the one you desire for your application. All the values implemented here are to serve as an example:
  • the epoxy is the default from the material database.
  • the fibre glass composition is taken from this paper. All the individual compounds are those as from the FLUKA material database.
  • the FR4 material density was taken from this data sheet.
  • the FR4 composition I used is of 60% epoxy and 40% fibre glass, but it really depends on the quality of PCBs (good one have around 50%/50%). Feel free to use the one you found with 70%-78%.
  1. As you might already observe, you can define composite materials recursively.
  2. Regarding dE/dx, you have full control over the material properties (see slide 15 of this presentation). Moreover, dE/dx is tabulated on a per-material basis: runtime the code pulls the dE/dx from tabulations at a given material index. Instead, nuclear interactions are isotope dependent (one needs not only the element composition but the isotopic composition as well; natural isotopic composition by default).

Hope it helps and let me know if there is anything else I could help with.



Hi, you are not supposed to fill the dE/dx field, unless for some very specific purposes you wish to use the stopping power of ANOTHER material when tracking particles inside the material you are defining. Also, normally you should not fill the atomic weight nor the material index, which are already properly set by FLUKA. All this is clearly indicated in the manual and reflected by @dprelipc file.
I’d refrain from overwriting material properties by MAT-PROP and STERNHEI, unless one has good reasons to do so.

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Dear Daniel and Francesco thank you a lot!