Abstract: A system for placing, soldering and inspecting component parts, such as soldered joints and electronic components, on a printed circuit board utilizes a transfer device for selecting and transferring specific electronic component parts to predetermined positions on a printed circuit board and holding each component part in the desired position by use of the transfer device during a reflow soldering operation to mechanically and electrically connect the component part to the printed circuit board. The reflow solderiung utilizes a laser beam for injecting thermal energy into each soldered joint to melt the soldered material. An infrared detector senses thermal radiation and/or reflected radiation from the heated solder material to discontinue the application of the laser beam to the solder material upon liquifaction of the solder material.

Abstract: A system for placing, soldering and inspecting component parts, such as soldered joints and electronic components, on a printed circuit board utilizes a transfer device for selecting and transferring specific electronic component parts to predetermined positions on a printed circuit board and holding each component part in the desired position by use of the transfer device during a reflow soldering operation to mechanically and electrically connect the component part to the printed circuit board. The reflow soldering utilizes a laser beam for injecting thermal energy into each soldered joint to melt the soldered material. An infrared detector senses thermal radiation and/or reflected radiation from the heated solder material to discontinue the application of the laser beam to the solder material upon liquifaction of the solder material.

Abstract: The melting of solder in a reflow soldering operation is detected by examining the rate of change of the solder temperature or by detecting a change in a surface reflectance characteristic of the solder which occurs upon melting.

Abstract: An apparatus for inspecting a device made up of a plurality of different infrared radiating elements includes an optical head which is moveable along X-Y coordinates above the fixed device to sequentially scan the infrared radiating elements. A laser beam source is operatively connected to the moveable head for injecting thermal energy into the infrared radiating elements and an infrared detector is provided for sensing the infrared radiation emanating from the elements. The infrared detector may be mounted directly on the moveable head or in a remote location wherein the detector would be connected to the moveable head by a flexible optical fiber. A second moveable head may be located on the opposite side of the device so that thermal energy from the laser source may be injected into opposite sides of the infrared radiating element.

Abstract: A controller for a spot-welding machine compares the temperature evolution at a site at which a spot weld is being made to a standard thermal history stored in a digital read/write memory in controlling the welding current for the weld. Standard thermal histories can be generated and written into the memory as needed by an operator of the welding machine to take into account changes in operating conditions. The temperature evolution of the spot-welding operation is monitored by detecting radiant energy whose intensity provides a measure of a temperature of the weld. Phosphorescent radiation from a thermographic phosphor located in a welding tip of the welding machine and thermal infrared radiation are preferred for monitoring the temperature evolution of the spot-welding operation.

Abstract: Control of spot weld quality is effected by observing the progress of heat generation within the weld and initiating automatic corrective action if the heating rate is initially too high or too low. A flexible optical fiber bundle has one end located in the welding tip and the other end optically coupled to an infrared detector. Due to the excellent thermal conductivity of the copper material of the welding tip, thermal energy is conducted very rapidly for a short distance into the tip during the weld formation so that the infrared detector produces an output signal proportional to the weld temperature. This signal is sampled and compared with a previously-recorded signal corresponding to the heating rate that produced a good spot weld in the material being welded.