It isn’t unusual to find out that something we’ve budgeted for ends up costing more than expected. When a carpenter begins a home remodeling project, they often find additional problems that drive up the cost. There’s a proverbial joke which states, “the cost of the car is only $100, but the wheels will cost you extra.” What may come as a surprise is that some of the unique requirements of having a circuit board assembled could also drive up its cost.
PCB manufacturing is by nature a customized process as each design is usually unique in its size, configuration, and purpose. But there are some aspects of building a board that can affect the cost more than others. Here we will take a look at some of the factors that can impact the cost of custom PCB assembly so that you will know what to expect on your next design.
Manufacturing Details that Affect the Cost of Custom PCB Assembly
The first factor that can add additional manufacturing cost to a printed circuit board, is if the design isn’t actually ready to be built yet. If it isn’t prepared, the manufacturer will have to spend time on engineering analysis and changes to incorporate design for manufacturability (DFM) details. Missing requirements for the design, such as controlled impedance routing specifications, can also add the final manufacturing costs.
Another problem that can add expense is if the documentation is incomplete or missing. The contract manufacturer will need a complete set of data to work from, including fabrication and assembly drawings, component location files, test data, and a bill of materials. An incomplete BOM will slow down manufacturing as the contract manufacturer will have to verify all the parts against the design database and check for their availability and price. Even small details such as an unmatched reference designator can cause significant manufacturing problems until the phantom part is identified. Missing or incorrect data like this will force additional meetings and dialog between the customer and the manufacturer to clarify the details, and slow down the manufacturing.
It is also important to work ahead with your manufacturer to plan out the board’s best configuration. Often, a PCB will go all the way through design without these details worked out ahead of time, and the customer will spend additional production costs that could have been designed out of the board. Here are some of the details to consider before committing to the final design configuration:
- Layer count: In some cases, the layer count can be reduced to save production costs, while in others, the layer count should be increased to satisfy signal integrity and other PCB performance issues.
- High density interconnect (HDI) design: Circuit boards with a high circuitry density and precise signal integrity requirements may need the tighter trace routing and microvias of an HDI design. But if the circuitry doesn’t require this, stay away from it as HDI technology increases the manufacturing costs.
- Controlled impedance routing: Circuit boards that require controlled impedance traces will need specific layer stackup requirements. To save PCB development costs, plan for this in advance to not have to go back and re-design a board to add extra layers.
- Finishes: How the board will be finished needs to be accounted for up-front, otherwise, you may be surprised at how much a specialized finish may cost. Not only does the lead-free process for RoHS requirements cost more than regular soldering, but it will have an effect on what components are used in the design as well.
Next, we’ll look at some specific examples of PCB assembly requirements that can affect how much you will pay for your board’s assembly.
Custom Assembly Requirements that Increase PCB Production Costs
When your PCB CM evaluates your board for manufacturing, it will either fall into their standard board assembly flow or a flow that will have to be adjusted for unique components or materials. Some components require non-standard assembly processes due to their sensitivity to the temperatures of the soldering process. Others may be sensitive to different portions of the assembly process, such as camera lenses that won’t survive the standard wash operation. In these cases, the components must be protected from these processes or manually assembled afterward.
Another problem that can affect your board is if some of its mechanical hardware is not ready for assembly when the rest of the board is. This problem can occur because of a subcontractor’s manufacturing process or incorrectly and designed hardware. Often a good PCB CM will catch and be able to correct errors like these, but it will still add time and expense to the manufacturing of the board.
One of the most customized processes to affect the manufacturing costs of the board is its testability. PCB testing is usually a unique process for each board. Sometimes it’s a simple little fixture and test program. Other times, it is a complex test setup and actual emulation of the end product. Most manufactured circuit boards will have some kind of testing plan created for it, and that is where the PCB CM capabilities can help.
CM’s test engineers will examine a new design to be manufactured, and present their recommendations for testing to the customer during the initial design review meeting. These recommendations will include what kind of testing process is needed and what type of fixture it will require. It will also have their guidance for specific test access on the board to facilitate the circuitry’s debugging.
Testing isn’t the only way a good PCB CM can help. There are other ways to help cut manufacturing costs and make a better board, which we will look at next.
How Your PCB Contract Manufacturer Can Help
Not only do you need for your printed circuit board to be built quickly and at the best price, but the final product needs to function the way that you intended. For this reason, the PCB contract manufacturer will want to ensure that the design and manufacturing plan is correct before production starts. To do this, the PCB CM will typically have an engineering staff available to perform the following services during the manufacturing of your circuit board:
- Engineering review and analysis
- BOM review and clean-up
- Design for manufacturing (DFM) review and recommendations
- Test engineering
At VSE, we know that you need to get the best ROI on your manufacturing expenses, and we also understand that your circuit boards have to operate as designed. Therefore we will review your design thoroughly before we begin production. One of the areas that we pay special attention to is the bill of materials to ensure no delays or added expenses with the components on your board. We will:
- Scrub your BOM to make sure that it is correct before PCB assembly.
- Analyze the BOM to find potential component lead-time and inventory issues.
- Review component life-cycle and identify parts that are going end of life (EOL).
- Recommend low-cost part alternatives or circuit changes for expensive components.
Recognizing these potential expenses to customer PCB assemblies and recommending solutions is the expertise we are proud to provide.
