Issue link: https://iconnect007.uberflip.com/i/1477844
76 SMT007 MAGAZINE I SEPTEMBER 2022 damage other areas of the board. Remove the cut-out trace piece and discard. An alternative to using the knife would be to clamp the board onto the milling bed mak- ing sure the board is parallel to the cutting tool. Size the cutting tool at half the width of the cut to be made. Make sure to protect the cut area so no foreign debris is le on the PCB. Clean aer cutting as previously described. Next use the continuity checker to make sure there is an electrical open between the cuts. Mix the epoxy per the manufacturers' rec- ommendations making sure you are aware of the humidity, temperature, and working time of the epoxy. In some cases, colorant needs to be added to color match the assembly. Using the edge of your knife, carefully fill in the gap (Figure 3) le by the missing trace. Cure the epoxy in an oven per the manufacturer's guide- lines. As a final step make sure the modification of board repair did not leave behind unintended damage to surrounding circuits while you were concentrating on the repair. Perform any remaining electrical tests as required. SMT007 Resource • IPC 7711/7721 Rework and Repair Modification of Printed Boards and Electronic Assemblies, Jan- uary 2017. Bob Wettermann is the principal of BEST Inc., a contract rework and repair facility in Chicago. For more information, contact info@solder.net. To read past columns, click here. Figure 3: Fill in the gap of the trace cut using PCB repair epoxy.