When physical damage usually in the form of scratched traces or mask, broken corners, lifted pads or damaged plated through holes comes up, the printed circuit board needs to be physically repaired. If desired or allowed by the customer these repairs require the proper PCB repair tools and techniques. The techniques need to be performed by those skilled in the art with experience in such repairs. Specific PCB repair tools designed to make repair technician’s jobs easier and faster.
There are several techniques, many of which were developed by the military, for use in the repair of printed circuit boards. These techniques have now been assembled and are being managed by the global trade organization the IPC. The IPC procedures for repair are spelled out in IPC-7721 “The repair of printed wiring boards”. This technical “how to” manual describes in detail the repair process, the tools required, the level of skill required-good, better and best- for each of the repair processes. PCB repair techniques in this document go all the way from the replating of gold fingers to solder mask repair to repair of laminate damage. The specifications call for customer involvement if a physical repair as outlined in the repair manual is required. The techniques for repair are broken down in this specification into beginner, advanced and expert PCB repair technician levels. In some cases, there may up to 4 different approved repair methods outlined in the IPC-7721, all of which will get the board back to a functioning PCB.
In addition to the “how to” instructions found in the IPC-7721 “The Repair of Printed Wiring Boards”, the manual also points to the tools required to completed the suggest repair. Each of the repair processes found in the PCB repair tools and techniques manual informs the user of not only the repair techniques but also the PCB repair tools. In most cases, they are very generic tools which can be procured from a variety of sources. The photographs in the standard supporting the documentation of the specification may include a specific vendor of the tool but in some cases, the “how to” section shows a generic sketch of the tool being used. For some procedures, very specific tools from very specific vendors are shown or are referred to in the procedure being discussed.
As an example, one of the procedures found in the IPC-7721 describing PCB repairs tools and techniques, “Repair of Printed Wiring Boards” is the PCB pad replacement technique. The IPC 7721 4.5.1 Land Repair, Epoxy Method and the 4.5.2 Land Repair, Dry Film Method, both get to the same end result-the replacement of a land which has been removed usually after a rework process has been done incorrectly or handling damage. Both methods refer to the following materials: Cleaner, microscope, soldering iron, tweezer, and wipes. Then in each of the methods, specific materials specific to that method-namely adhesive, circuit frames, and adhesive film are spelled out in the detailing of each technique. Each of the process steps is enumerated in detail so that both the PCB repair process steps and the materials can be used to complete the repair.
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