My introduction to electronics was as a technician. Basically, that meant that I had to understand a board’s operation as well as the designer in order to adequately test it and make repairs, if necessary. However, the designer got paid a whole lot more than I did, which is a major reason I learned to design PCBs. As luck would have it, the demand for the type of PCB technician that I was has declined, and today, the position is not quite what it was back then. It seems that as components and board size decreased, so did the market for bench repair technicians with the ability to repair circuit boards down to the component level. However, the increased production of circuit boards has opened opportunities for PCB manufacturing and test technicians who enjoy status as experts, earning substantially more than I used to doing PCB maintenance.
Performing PCB maintenance
The value of those early years far exceeded the salary and they have helped me immeasurably as an engineer. I will admit that I enjoy the simplicity of plug and play boards that are easily replaced; however, I admire and share solidarity with those who have the skill to manually solder and wick (or desolder) and use a pump and tweezers. And although repairing circuit boards is less common than it once was, the need for persons with the skills to do so still exists. So, let’s take a look at when repairs should and/or are done and how to design boards to make the job easier for those who perform PCB maintenance.
When Is PCB Maintenance Used?
Unfortunately, PCBs, just as all other electrical or mechanical devices do, fail. Fortunately, in most cases, boards can simply be replaced and operation resumed. This is possible due to the low cost of mass-produced solid-state components, which comprise virtually all electronic devices. There are, however, situations where simply replacing boards may not be the best course of action.
Electronic devices and systems typically are sold with warranties or guarantees for a certain operational lifetime. Warranty terms and lengths vary; however, it is common for commercial electronics product warranties to be for periods of 90 days to one year. Circuit boards and electronics for critical systems devices, such as for aerospace electronics or medical devices, are subject to stricter design standards and guidelines. Periods for these devices can be for much longer. If failure does occur prematurely, the supplier or developer is responsible for either replacement or repair of the defective device or entire system or product.
The decision of whether or not to perform bench repair of circuit boards is not a simple one for developers or suppliers. Obviously, the cost of repair compared to the cost of building a new board is a major factor; however, there are other PCB maintenance considerations that should be weighed. The three most important are:
PCB Maintenance Considerations
1. What type of failure is it?
The first consideration is the type of failure. PCBs fail for a number of reasons, including the following.
- Trace damage
- Physical damage
- Component failure
- Power damage
2. How often does it occur?
It is also important to determine whether the failure is recurrent or an isolated event. Note that every board does not have to fail for a problem to be recurrent. It is only necessary that the failure rate is above an acceptable threshold, which can be determined by risk analysis.
3. Is redesign needed?
Whether or not the source of failure can or should be corrected by redevelopment is a major consideration. For ongoing or planned future supply, it is probably worthwhile to cycle the board through further iteration cycles to improve design quality.
Performing PCB maintenance does require that skilled personnel are available and have the time to diagnose and solve the issue. For some board deployments; industrial environments, for example, the end-user may have the capability to perform needed repairs. However, it is more common that the developer will need to perform these tasks. Regardless of who performs the repairs, it is advantageous if the board is designed to facilitate easy PCB maintenance.
Designing for Easy PCB Maintenance
Some failures damage the board beyond repair. For example, excessive current surges can cause fires that burn components and board material. And overstressed boards may acquire severe fractures or break completely. More often than not, these types of failures are isolated events and/or are outside the normal performance requirements of the PCB and replacement is the best option. Issues such as trace and via damage, which if recurrent may indicate redesign is required, are difficult to repair and require special expertise. On the other hand, component replacements can be done simply and quickly.
It may seem that PCB maintenance is not a development issue. This is largely correct; however, if board failures are occurring, especially recurrently, that is an indication that the issues may be addressable by further development. And there are design actions which will make board maintenance easier, faster and less costly and may minimize the probability of redevelopment. These include:
Design Tips for Easy PCB Maintenance
- Use easy disconnect connectors
The use of common PCB connectors, such as plugs and sockets allow for simple removal of the affected board for repair.
- Incorporate pre-built modules
Pre-built modules, which consist of multiple components and/or circuits, not only expedite board design but can also aid in faster PCB maintenance as compared to multiple components and traces.
- Use SMDs, if possible
For internal failure of a component or IC, SMDs are much easier to replace than through-hole components. However, if the failure is within the board from an SMD or BGA, the repair requires skill and precision.
- Use readily available components
You should ensure that your design does not include components that are in short supply as this could affect replacements and future production.
- Use readily repairable materials
Board and trace issues can be repaired in some cases provided the material selected is reworkable. Otherwise, the board will need to be replaced or remanufactured.
|Tempo‘s Custom PCB Manufacturing Service
Although not as common as it once was, PCB maintenance is still the best option for a number of situations. Therefore, you should incorporate design measures to make the process of repairing your boards as easy as possible. At Tempo Automation, the industry leader in fast, high-quality PCB prototype and low-volume production, we will help you to minimize the probability will need repair.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.