Issue link: https://iconnect007.uberflip.com/i/1466505
72 SMT007 MAGAZINE I MAY 2022 capacitors, LEDs, glass bodied fuses, and oth- ers which are near the rework area. Make sure to examine the side opposite of the component to protect neighboring components from ther- mal damage prior to using heat to remove the component. Prior to removing the component, it is always good practice to develop a profile board. In a profile board, thermocouples are embedded in key locations at and around the component location (on a process development board) to measure board and soldering temperatures at various locations. Typical locations to place these thermocouples are at the ground plane pad and at least two locations opposite one another on the connector. More thermocou- ples may be added at locations near heat-sen- sitive devices. e rework removal profile can be more aggressive than typical reflow norms since in most cases, the component will be scrapped. Make sure the bottom side of the board is between125–150°C through heating of a bot- tom heater. Both IR and hot air sources can be used as a rework heat source. When profiling, make sure that the solder has turned into the liquidus phase by carefully observing the com- ponent either on the video feed provided by the rework station or by carefully peering at the solder/board interface using a flashlight. Once you can observe that the solder has obtained the liquidus state, activate the removal cycle and pick up the connector. As in other area array or more complex com- ponent rework processes, aer the assembly comes down to room temperature it is time to prep the site by wicking solder from the pads and cleaning the location. Finally, the pads should be inspected for damage. For these component body styles it is best to use a miniature stencil or a programmable solder paste dispenser to affix the replacement connector to the PCB. e adhesive-backed stencil method is the least time-consum- ing method for selectively re-applying solder paste to the pads. e center ground pattern may need to be "window paned" to prevent too much solder from "liing up" the connec- tor leads. Aer peeling off the release liner from the stencil, align the stencil apertures, starting at one of the corners. Make the final fine alignment adjustments taking advantage of the repositionable adhesive which will keep also serve to affix the stencil into place once aligned. Using a small squeegee, roll solder paste through the apertures and then slowly peel up the stencil making sure it is perpendic- ular to the board surface. Examine the solder "bricks" formed on the PCB to make sure the solder paste has been applied to all locations consistently. Another approach for stenciling is to use a "mini" stainless stencil that mimics the original stencil design at the rework location. is tech- nique takes a great deal more skill to get right and not "smear" the solder paste. A program- mable dispenser, while taking some time to set up and program, will also provide for a consis- tent solder paste volume at each of the pads. Aer the solder paste is deposited, place the PCB onto the rework station making sure the PCB is properly supported. Recall the proper reflow profile in the rework station and begin the reflow cycle. Aer reflow, a few more steps need to be taken to compete the rework process. Aer the board has cooled and the assembly has been removed from the rework machine, the rework area needs to be cleaned and then visu- ally inspected per the IPC-A-610 standards. Since the ground connection is a non-inspect- able area of the connector, this rework needs Prior to removing the component, it is always good practice to develop a profile board.