... imbibitionIT industry,Keyboard productsGeneral FR-4 differs from high Tg FR-4: in the hot state, especially in ... differences in thermal expansion and other various conditions, high Tg products significantly better than conventional PCB substrate material. Parameter: ... PCB .Specifications TechnologyNotesNumber of Layers1-28 LayersBoard MaterialsFR4 (Tg 135, 145, 170,180)Rogers(RO4350,4003,5880,3003 ...