Material CEM-1

The materials suitable under the CEM-1 specification in classification of NEMA – the most widespread materials for production of 1-layers printed-circuit boards.

Standard CEM-1 material is composite material on a cellulose basis with one layer of glass fibre laminate (FR-4) on a surface. Usually CEM-1 has milky-white color.

The feature of this material is the impossibility of realization the metallization through holes, thus, this material can be used only for production of 1-layer printed-circuit boards.

Standard CEM-1 satisfies to combustibility class UL94-V0, as FR-4 material. Mechanical characteristics of CEM-1 are little bit worse, than at FR-4: CEM-1 is more fragile. The dielectric constant and a tangent of angle of dielectric losses of both materials are differ insignificantly.

Thus, CEM-1 is a cheaper alternative for FR-4 material for production of 1-layer printed-circuit boards.

Properties		Test conditions	Units of measure	Values
Superficial resistance	at the increased humidity	F	MOhm	> 1000000
	at the increased temperature	E-24/125
Volume resistance	at the increased humidity	F	MOhm * cm	> 10000
	at the increased temperature	E-24/125		> 1000
Dielectric breakdown		D-48/50 + D-0.5/23	KV	> 40
Dielectric permeability, for 1MHz		C-40/23/50		< 5.4
Tangent of angle of dielectric losses, for 1MHz		C-40/23/50		< 0.035
Arc resistance		D-48/50 + D-0.5/23	Sec	> 60
Tensile strength for copper foil thickness 35 mkm	average	A	N/mm	> 0.96
	after thermal influence	A	N/mm	> 0.96
The requirement for soldering		288 C, 20 sec
		288 C, 20 sec		it isn't stratified
Durability on a bend	longitudinal	A	MPa	> 240
	cross	A	MPa	> 190
Water absorption		E-1/105 + des + D-24/23	%	< 0.3
		E-1/105 + des	%
Combustibility		A & E-1/105 + des		94V-0
Stability of the sizes		E-4/105 + des + E-2/150	mkm/cm

Symbols in test conditions have the following interpretation:

A – without preliminary preparation

С - preliminary preparation in damp air

D - preliminary preparation in the distilled water

E - preliminary preparation at this temperature

F - testing after a series of heatings by hot damp air

des - preliminary preparation by drying in drying camera

T - testing at this temperature