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. |
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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 |