Abstract: A method of assembling a substrate and an electrical or electronic component, the component having electrically conductive leads with surfaces of an alloy from the list consisting of tin, nickel, tin copper, tin silver, nickel palladium, gold palladium, and silver palladium, and the leads being soldered to copper-based terminals of the substrate by a solder alloy, the solder alloy comprising, by weight, 99.3% tin and 0.7% copper. The soldering takes place in a chamber having a nitrogen inert atmosphere. Lead solder is thus avoided.

Abstract: In an electron-fushion welding process a fault, e.g. due to incorrect assembly of the pipe joint components, is detected by sensing the welding current and emitting a signal to actuate an audible or visible alarm and/or to interrupt the welding process, if the welding current increases unexpectedly. A reference signal dependent upon the current dependent signal produced by the sensor and RMS to DC converter at a time t.sub.1 is held by a converter and is compared by a comparator with the current dependent signal transmitted through converter at subsequent intervals. So that the device does not react to transient current increase a delay arrangement delays the output signal for a given time.

Abstract: An electro-fusion fitting for coupling thermoplastic pipes incorporates a heating coil (2) and has a resistor (6) with a value chosen in accordance with the power to be supplied to the coil connected between a main terminal (4) and an auxiliary terminal (5). Control apparatus is adapted to sense the resistance value and supply electric current to the coil for a predetermined time set automatically according to the resistance value.