The 40-60 percent resin to glass fibre rule is a bit ancient.
It excludes the fillers to improve the thermal/mechanical/flame resistant properties, e.g. silica and aluminum silicate. (curing accelerators can be taken in with the epoxy resin)
In reality, the epoxy resin weight fraction in fibreglass board ranges from well over 45% to just under 60%.
50/50 is more common, which also means the glass fiber weight content is under 50%.
Specific weight of FR-4 board (minus the copper clad) is 1850 kg/m3
Interesting read : www.ul.com/global/documents/offerin...ingboards/2013FR4ExternalWebinar_20130820.pdf
(polyester resin specific weight is 10% higher than vinyl-ester and epoxy resin. Just using vinyl-ester/epoxy for building a boat hull can save an interesting amount of weight, due to the high resin weight content. Net cost is 1:2:4 though)
It excludes the fillers to improve the thermal/mechanical/flame resistant properties, e.g. silica and aluminum silicate. (curing accelerators can be taken in with the epoxy resin)
In reality, the epoxy resin weight fraction in fibreglass board ranges from well over 45% to just under 60%.
50/50 is more common, which also means the glass fiber weight content is under 50%.
Specific weight of FR-4 board (minus the copper clad) is 1850 kg/m3
Interesting read : www.ul.com/global/documents/offerin...ingboards/2013FR4ExternalWebinar_20130820.pdf
(polyester resin specific weight is 10% higher than vinyl-ester and epoxy resin. Just using vinyl-ester/epoxy for building a boat hull can save an interesting amount of weight, due to the high resin weight content. Net cost is 1:2:4 though)
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