Virtual Exhibition

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.
Materials of 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