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80 PCB007 MAGAZINE I AUGUST 2024 As a basis for the parametric LCI model, a simplified process flow for PCB production is used (Figure 2). For each process step, the energy consumption, water usage, and gener- ated waste are calculated. Input materials con- sist of the base material in the form of cop- per-clad laminates and prepregs, copper foil, the solder mask material, and the material(s) of the surface finish. In the metallization step, copper is deposited onto the PCB for which plating chemicals and electroplating copper electrodes constitute the input material. e main auxiliary materials are photoresist and a broad range of etching, surface treatment, and cleaning chemicals. Press pads and release foil for lamination as well as drill bits and entry and backup material for drilling are other examples of auxiliary materials. Input parameters for the parametric LCI consist of the area of the PCB, the number of layers, the total thickness, base material, sur- face finish, and the presence of solder mask. Further design details on the copper area on the top, bottom and inner layers, the area of the solderable finish, as well as the thickness of the copper foil and laminates can be included if available. Output parameters per process step are water usage (tap or deionized) and energy consumption (electricity and gas). All calcula- tions are performed to represent 1 m2 of PCB. e output parameters can be transferred to an LCA tool to perform the impact assessment or used directly as a metric for eco-design. A final and crucial input parameter is the panel occupation (%), defined as the com- bined area of actual PCBs on the panel com- pared to the panel size. PCBs are produced on large production panels that can range from 9" (229 mm) x 12" (305 mm) up to 18" (457 mm) x 24" (610 mm) or larger for high-volume PCB production. Only part of the area is (and can be) used for actual PCB real estate. Typically, a one-inch border is kept free to avoid edge effects. Furthermore, coupons for process con- trol and outgoing inspection are included on the panel. Especially for high-reliability appli- cations (IPC Class 3), a large number of cou- pons is required and thus the available space for actual PCBs is further reduced. If multi- ple PCBs are present on the panel, their size and shape will determine how efficient the remaining panel area is used. Considering, as Figure 2: Simplified process flow for PCB production as used for the parametric LCI model.