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PAINTED ENCLOSURES


Special

For plastic enclosures, in smaller volumes, a customer-specific colour is best achieved by painting. Moulding with a customer specified colour of the plastic material is possible at a 500-piece level, but becomes more cost effective for single runs that exceed 1000 pieces (for more information see special colour moulding).

For aluminium enclosures, painting is the only option for custom colours. The preferred method uses polyester powder paint, in standard RAL colours. Thorough surface preparation and cleaning is the key in achieving a high-quality and long-lasting finish. Other surface treatments are available for aluminium enclosures. Please contact the factory for more details.

EMC
Plastic Enclosures

A variety of shielding methods are available for plastic enclosures. The characteristics of these methods are shown in the following table. As the table indicates, Ni-Painting is the most cost-effective option, while Ag-painting is the most costly.

In addition to the interior conductive coating, attaining a high degree of shielding requires a special conductive gasket material be installed. Excellent results in sealing the base-cover joint have been achieved using a silver filled elastomeric gasket, such as CHO-SEAL 1350. In combination with Ni-painting, a relatively effective level of shielding can be achieved.


EMC

EMC Shielding Data Sheet of Plastic enclosures

Shielding
method
Coating
thickness
microns
EMI-shielding
attenuation dB
ASTM ES 7-83
Sheet
resistance
Ohm/square
Relative
coating
costs


  Ni-painting


50

35-60 dB

0,5

1


  Ag-painting
  (fast drying silver)

  Ag-painting

  Ag/Cu-painting

  Cu-painting

  Graphite-Painting

  Al Vacuum coating

  Zn-Arc



25

25

50

50

50


1

50



55-65 dB
(100 MHz)
60 - 65 dB

60 - 65 dB

60 - 65 dB

40 dB (100 MHz)


40 dB (100 MHz)

60 - 65 dB


0.01

0.1

0.2

0.25

10 (25 micr.)


0.1

0.25 - 0.8


55

50

3

2

2


10

5



Shielding effect of Ni-painting


dB          

60

40

20

Ni-painting

Diagram:
Telecom Finland Ltd,
Testing laboratory.
Test report
TL 940015

                  30 MHz                                                      1030 MHz 


Aluminium Enclosures

Aluminium enclosures are inherently conductive, making them ideal for EMI/RFI protection. Only the addition of a conductive gasket is required. However, the specific enclosure must be prepared in order for it to receive the conductive gasket: the gasket groove channel needs to be either unpainted or stripped of paint. The former method is preferable and is available by special order from the factory.

Standard CHO-SEAL 1350 gasket characteristics. This gasket is used by FIBOX for both plastic and aluminium enclosures.

Characteristic
Test procedure
  Elastomer binder   Silicone
  Conductive filler   Ag/Glass
  Volume resistivity Ohm-cm, 
  max. as supplied without
  pressure-sensitive adhesive
0.01 CEPS-0002
  Hardness 65 +/- 5 Shore A
  Elongation, min. 75 % ASTM-D412
  Compression set, 70 hrs.
  at 100 ° C, max.
30 % ASTM-D395
Method B
  Low temperature flex
  TR10, min.
- 55 ° C ASTM-D1329
  Shielding effectiveness dB
  100 Mhz E-field
  500 MHz E-field
  2 GHz Plane Wave
  10 GHz Plane Wave

100
100
90
8
Modified
MIL-STD-285
Reference measured
through 610x610 mm
opening
  Volume resistivity after
  heat aging Ohm-cm, max.
0.01 CEPS-0002
  Post tensile set volume
  resistivity Ohm-cm, max
0.01 CEPS-0002


 Shielding effect of aluminium enclosures


dB
100

80

60


Aluminium shielding
30 MHz                                                   1030 MHz

Diagram:
Telecom Finland Ltd, Testing laboratory.
Test report
TL 940015

RFI shielding effect of FIBOX Euronord II AL 121208 aluminium enclosure; unpainted interior and Cho-Seal 1350 conductive gasket.


NOMENCLATURE SCREEN-PRINTED ENCLOSURES



Plastic and aluminium enclosures

• Silk screen-printing is available and recommended for enclosure batches of less than 1000 pieces. It is ideal for flat surfaces and large areas and is available in multiple colours.



Tampo printing

Tampo (Pad) printing is the best solution for batches of over 1000 pieces. It is suitable for printing on both flat and curved surfaces and compact areas such as inside surfaces. The total size is more limited than in silk screening.

Both methods offer printing with 1 to 3 colours for RAL or PMS specifications.

B/W paper or film original suitable for printing will ensure a good printing result. Please consult the factory for specific details and requirements of reproducible artwork.


Printed2

Printed

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