Basic equipment used for qualifying components consists of standard tools like Multi meters, Power Supplies, Digital Storage Oscilloscopes, Signal/Frequency Generators, LCR, Power Meters etc. When thermal qualifications are required, additional equipment such as thermal chambers, data loggers, circular chart recorders, temperature controllers and circulating fans. In the picture above, there is a thermal chamber that was made by using multi-socket strips affixed with various wattage light bulbs as heat sources. By mixing and matching the different wattage ratings of the bulbs and measuring the temperature after stabilization inside the chamber, the temperature can be increased or decreased in predetermined steps by adding or removing light bulbs for thermal analysis. The advantage of this design is low cost while providing table top access. A grommeted opening is used to port through the thermocouples which are connected to a standard data logger. The fan is used to circulate the air inside the heated chamber to promote uniformity throughout the ambient. The thermocouples are either attached to component, PCB, or enclosure surfaces, or suspended in the air in various locations. The initial measurements are taken without any bulbs on. Subsequent measurements are taken at various ambient temperatures to determine the individual component temperature rises respectively. Key to a successful evaluation is the condition that the unit under test, UUT is operational. Live outputs from the operating circuits are advisable to monitor and detect a degradation in performance with temperature increases.
This test bench is set up to test multiple units concurrently. The sample cases on the right of the picture contain parts submitted for approval. This particular bench is set up with 10 separate CATV video feeds that are in-turn fed to 10 PC board assemblies. The sample parts were ordered in sets of 10 so that each sample could be tested across the ten individual circuits. In the event that there was more than one sample part requirement per board, then the sample count was increased in order to accommodate all positions on the board where the part had a reference designator. The sample parts were soldered in by hand or re-flowed as required. The live video output of each circuit was fed into a video multiplexer where functional performance could be monitored in real time. When qualifying a new part, there must be a significant sample size to confirm suitability for approval. Use the qualification form “Component Board Evaluation Record” under the forms section on this website.