For mid-size EMS providers, costs of rework can add up quickly. By some estimates, rework alone could result in tens of thousands of dollars in annual losses. Yet these costs aren't as high ascompletely scrapping a board, which can be almost triple the annual costs of repair. In terms of cost, the question of whether to repair or scrap is relatively simple: It's almost always worth it to repair.
Complex, high density PCB assemblies are simply too high in value to be scrapped. Even smaller boards with fewer components should be repaired because of the tight production runs of Just-In-Time manufacturing standards. Ideally, an experienced EMS provider will have strong processes in place, so that solder defects, wrong parts, and opens and shorts can be caught early on. But defects are inevitable, especially on complex, multi-layer assemblies with an ever-increasing amount of SMT components.
However, there are other factors to consider aside from cost. If a board that costs $1,000 requires 8 hours of repair, and your shop rate is $100/hour, should you repair or scrap? Financially speaking, this is a no-brainer: repair the board for $800. But what if the repair is unsuccessful? You're now facing the cost of rework plus the cost of manufacturing a completely new board. In other words, assess the risk factors associated with rework.
It's also a good idea to evaluate your processes. How well defined is your repair operation? Have you had to make this repair before? How experienced is your staff? Are there metrics on your repairs? Each of these questions can help to refine your rework processes and make it easier to decide when to scrap or repair.
Lastly, many CMs and EMS providers have a material review board (MRB), which is composed of procurers, quality engineers, and production engineers who decide what to do with wrong components, defective materials, or damaged products. Nowadays, MRB is facilitated with software like UniPoint, which leans down the MRP into a task oriented process.
Deciding when to scrap or when to repair a board is never an easy decision, especially as the complexity of a design rises. Having a strong understanding of the costs involved with both the board to be repaired, as well as the labor involved in the repair, is essential to making the correct choice. Being certain of your in-house capabilities is also critical to deciding when to repair or when to scrap a board.
Statement: This post is only the personal view of the author and does not represent the opinions of ALLPCB.com.