![]() Temeperatures of heat sensitive components such as plastic connectors, glass diodes or cameras may need to be monitored so as not to be damaged by the rework process.Ī thermocouple embedded into the solder ball is the preferred profiling method as it provides the most accurate BGA solder joint temperature readings, serves to reduce the chances for damage to nearby components on the boards being reworked, while reducing the chances for board damage or warpage. When a profile board is made available thermocouples can be embedded into the component die being reworked as well as neighboring solder joints which may be damaged if they are over the liquidus temperature. Floating air thermocouples or thermocouples attached next to the part being reworked are NOT accurate solder temperature indicators rather a temperature probe installed inside a solder ball to be reflowed is the most sure method for determining the proper reflow temperature for each BGA location. Whatever the method used, it is critical to record the BGA solder joint, the top of the component and corner temperatures on the BGA package. One method assumes that a profile PCB and part is available in order to establish the BGA rework profile, while another assumes that no dedicated profile PCB exists. The method used is a function of the availability of a sample or test BGA rework profile PCB and component to be reworked. There are several methods available to correctly identify and build a BGA rework profile. By creating a BGA rework profile for each location the risk of over or under heat exposure to components, lifted pads, damaged solder mask as well as improperly soldered joints is minimized. Each specific BGA site to be reworked must have a BGA rework profile developed individually as each site has variations which affect the reflow process including the location of adjacent components, heat-sinking variations of the PCB internal layers and the thermal mass of the component itself. Thermal profiling is required for several operations in the BGA rework process including device removal and reflow. ![]() Develop Process Develop Profile Part Removal Site Preparation Placement Reflow Inspection
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