Strategies for Recapturing Obsolete Circuit Board Inventory

摘要

Rework. The word itself conjures the sound of flushing money down the drain. Regardless of the cause―manufacturing defect, assembly defect, design defect, or engineering change―the object is minimization. Improved design software, automated manufacturing and tighter controls have been successful in reducing many sources of defect rates in the fabrication process. Such is not the case, however, with engineering changes. Ravenous consumer demand for something new, better, and cheaper has created an environment of nearly instantaneous obsolescence. Increasingly rapid design cycles and the deep volume discounts offered by offshore PCB manufacturers routinely generate obsolete PCB inventories ranging from tens to thousands of boards. Inventories of obsolete circuit boards are not a new problem for this industry, but the magnitude of the problem has changed dramatically. Each new generation of a product typically has major changes at the semiconductor level, but only minor changes at the printed circuit board level. Although any one set of engineering changes at the PCB level may only amount to a few lines of circuitry, the pace of these changes has increased steadily over the last two decades. Modifying existing inventory to recapture a significant portion of the sunk costs―tens to hundreds of dollars per board―would seem a worthwhile endeavor (Ref. 1). Even in just-in-time manufacturing operations with no remainder inventory, there can be advantages to ordering an existing circuit design with the intent of making some post-fabrication modifications. Although some changes are more difficult to implement than others, returning to ground zero in the design and manufacturing process can eliminate the possibility of a product being first to market (Ref. 2).