Material FR-4

The materials covered by the specification FR-4 classification NEMA, is most often used for the production of double-sided and multilayer printed circuit boards.

Standard FR-4 is a composite material based on glass fibers (glass fiber). Standard FR-4 of 1.6 mm thickness is composed of eight layers ("prepregs") fiberglass. The central layer is usually the manufacturer's logo and its color reflects the Fire class of the material: red & ndash; & nbsp; UL94-V0, blue & ndash; & nbsp; UL94-HB.

Usually, FR-4 is transparent, standard green solder mask defined by the color applied to the finished printed circuit board.

So, FR-4 is the most common worldwide base material for the production of double-sided and multilayer printed circuit boards, as well as being for the production of single-sided printed circuit boards with high requirements for mechanical strength.

FR-4 material characteristics:

Properties		The test conditions	Units of measure	Values
The surface resistance	high humidity	F	Megohm	> 1000000
	high temperature	E-24/125
Volume resistance	high humidity	F	Megohm * cm	> 10000
	high temperature	E-24/125		> 1000
Dielectric breakdown		D-48/50 + D-0.5/23	KV	> 40
The dielectric constant at 1 MHz		C-40/23/50		< 5.4
The dielectric loss tangent at 1 MHz		C-40/23/50		< 0.035
Дугостойкость		D-48/50 + D-0.5/23	sec	> 60
Прочность на разрыв при слое меди 35 мкм	усредненный	A	N/mm	> 1.4
	после термического воздействия	A	N/mm	> 1.4
The requirement for soldering		288 С, 20 сек		not stratified
		288 С, 20 сек
Flexural strength	longitudinal	A	MPa	> 410
	transverse	A	MPa	> 340
Water Absorption		E-1/105 + des + D-24/23	%	0.1-0.77	< 0.8
				0.78-3.2	< 0.35
		E-1/105 + des	%
Flammability		A & E-1/105 + des		94V-0
Dimentions stability		E-4/105 + des + E-2/150	mkm/cm	+-4.92