PCB Supplier Evaluation And Qualification| 25 February, 1998
PCB Fabrication Supplier Evaluation And Qualification Made Easier
Supplier evaluation and qualification often is left to uninformed industry references or vague suggestions made by sales unprofessionals. This discussion is met to enhance a customer's ability to better evaluate and qualify printed circuit board fabrication suppliers when there is a lack of technical expertise. Start with the supplier's laboratory. This is where a supplier's best or worst indications of process control (management) becomes apparent. This is true because both preventive and reactionary, or quality verification, capabilities are presented. From a preventive standpoint, a supplier's laboratory clearly shows how well processes are first analyzed, then maintained and managed. From the standpoint of reaction or quality verification, the laboratory has the capability to show x-sections either indicating acceptable quality or the need for corrective action. First, any multilayer production facility must have a complete, competently managed laboratory. If not, a customer should simply not consider doing business there. The reasons are, to me, obvious as there is no way to ensure processes are managed (instead of results as defect) when there is no way to know either what goes into the process or what it effects. The laboratory tells both and how well processes are being maintained and managed. This is true for chemicals, materials, and physical operations as lamination, drilling, and imaging - as examples. "Up front," chemistries must be added to ensure solutions (etchants, plating baths, etch back chemicals, cleaners, and other requirements) are composed as specified. Then, additions continuously must be made, or solutions replaced, to ensure the right chemical balance to effectively manage a particular process to effect customer specified quality. Additionally, logs must be kept not as written numbers or text, but as graphic information as range or control charts. This information clearly shows operators, engineers, addition specialists, and management the condition of each element, its need, and its ability to be managed. "Out back," the effects of analysis, adds, and process management primarily are determined using laboratory x-sectional analysis. All process capabilities, and their effects, are easily determined using this method before and after thermal stress and/or shock. If an etch back solution is not maintained effectively, the effect may be resin smear. When a plating chemistry is not managed as required, the effect may be plating cracks, voids, or other anomalies. And so on. We agree with the IPC that too much information, as useless data, is detrimental in determining a supplier's ability to produce quality product. We simply would suggest knowing where to start and end the supplier evaluation and qualification process. They might easily start and end at the same place - a supplier's laboratory. This is an abstract of an article written by Earl Moon - Proof Of Design. More information available at firstname.lastname@example.org or by calling 408-734-9700 X103.