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52 SMT Magazine • February 2017 assembly process also made up of raw materials and potentially other subassemblies. Thus, the IPC-1782 task group thought that the structure of traceability data should align with this physi- cal reality. Figure 1 is a simple illustration of this structure. The assembly cell, here identified as "724435," contains data about the work order and process sequence, BOM, the process trace- ability data, which is a record of events and transactions that have taken place during the assembly process, and the materials traceability data which contains information about specific raw materials, as well as other "roots" of infor- mation about each subassembly. A raw material is defined as any component that does not have a traceability record. Because this is a modular approach, the traceability de- tail of subassemblies can be combined easily at a later date, either when the subassembly is used, or even later, as long as the unique ID of the subassembly is recorded. The subassembly data can later be imported or simply referred to when stored in a connected system. Then, specific cells of information that con- tain different attributes are defined for each of the materials and processes. The IPC-1782 stan- dard lists the requirements for data capture for each of these cells, relevant to the specific level of traceability chosen: M1 through M4, and P1 through P4. In the case of process traceability, common elements of traceability data apply to all pro- cesses and then additional requirements are de- pendent on the specific process type. For exam- ple, common elements are process name or ID, time in and out of each PCB, etc. Specific data by machine type would include the list of ma- terials consumed for an SMT process as well as details of machine errors during the operation, whereas a test process would include a pass and fail result, as well as process measurement data. For all the materials identified as being used at each process, the associated material trace- ability data cells are referenced. Information in these cells can include unique material IDs (as well as unique carrier IDs), supplier, date code, etc. The method of linking material traceability data through the use of unique IDs and the cel- lular structure of the data means that, at high- er levels of traceability, data does not need to be repeated within the data structure. Any specif- THE NEW IPC STANDARD FOR TRACEABILITY Figure 1: The hierarchical data structure approach adopted by the IPC-1782 standard.