MECHANICAL PARAMETERS

Explanation of Dimension Code

Each Resistor Type is assigned a 4 digit code, the first 2 digits give the nominal Active Diameter (D) in mm and the last 2 digits give the nominal Active Length (L) of the Resistor in mm. From this information the Volume of Active Material (v) may be determined.

Construction

The Tinned Copper lead terminations are attached to the Copper metallised contact on the Resistor body opposing flat surfaces, with high melting point solder. This permits reliable short time operation at temperatures up to 200 °C.

Coating

The coating consists of a high quality epoxy resin applied by fluidised bed technique. The coating finish is hard, smooth and has good appearance to harmonise with other electronic components.

The Resistor leads may be preformed to fit Printed Circuit Boards (PCB's) provided certain precautions are observed. During preforming, the Resistor ends should be grasped between thumb and forefinger. Examine the wire at the Resistor body junction to ensure the coating is not cracked.

If this range of Resistors experience surface temperatures regularly in excess of 150 °C, the coating will tend to degrade slightly, becoming 'coffee coloured'. Though unsightly, performance is not compromised.

Whilst the coating can reduce the rate of moisture ingress, it is not impervious to liquids.

Terminations / Soldering

The Tinned Copper wire lead terminations are 0.9mm in Diameter (AB 912 - AB 993) and 1.1mm in Diameter (AB 058 - AB 186) and require, as a minimum, PCB mounting holes of 1.2mm and 1.5mm Diameter respectively.

Soldering is permissible with mildly activated fluxed solders with liquidous properties less than 230 °C.

Coefficient of Linear Expansion

In the range + 4 x 10 ^-6 to +10 x 10 ^-6 per °C depending on material resistivity.