A recent online purchase concluded with a survey question, “How did you hear about us?” I honestly couldn’t remember how I had heard of them or what had convinced me to buy their product. Fortunately, with a reputable online shopping service, there’s a good chance that you’ll do okay with an impulse purchase. However, when you purchase goods or services that can make or break your business, it pays to know exactly what you’re buying. A good example is contracting with a vendor to fabricate an electronic design into bare circuit boards.
There is a lot to understand about the printed circuit board manufacturing business to choose an ideal PCB fabricator. You have to know the physical size and shape of the board, how many layers it will have, what its electrical requirements will be, and its materials. You also need to know which fabrication shops will give you the best results for your time and money. Here is where forming a solid relationship with the PCB contract manufacturer that will assemble your boards can help. PCB CMs understand both the fabrication and assembly side of manufacturing a circuit board, and they can choose the best PCB fabrication shop to work with to produce a high-quality board. Here’s how.
Different Fabrication Vendors, Different Results
There are many variations in circuit boards’ size, layer count, technology type, complexity, and the materials used in their fabrication. Many PCB fabricators don’t build the full range of these different board types and will specialize in one or another:
- Four layers or less
- Six layers or more
- Large boards such as backplanes
- Controlled impedance requirements
- High density interconnects
- Flex or rigid-flex circuits
Another differentiator between PCB fabricators is the production volume. Some vendors specialize in low volumes for quick prototypes or NPI builds, while others may focus on large volumes for long-term production. Circuit boards also differ in material composition, which is determined by the electrical, environmental, and physical needs of the circuit board:
- Standard: FR-4 is the material used for most printed circuit board fabrication. It is a laminate material designated as a flame retardant (FR), with a woven glass-reinforced epoxy resin (4). It is an excellent material for most PCB applications used universally throughout the industry.
- High-speed: Circuit boards that run at higher speeds and high-frequencies such as RF and microwave applications can exceed the dielectric capabilities of standard FR-4 materials. PCB fabricators may use advanced materials, such as enhanced epoxy resins and PTFE (Teflon), that have better electrical properties to prevent dielectric breakdown.
- Operating environment: Circuit boards used in harsh environmental conditions such as spaceflight, engines, or industrial uses such as drilling equipment may require more robust materials in their construction. Polyimides are often used to counter tough environments due to their enhanced thermal and mechanical properties.
All of the PCB fabrication options listed above are typically not covered by a single vendor. Contract manufacturers understand this and will have a list of trusted vendors with different specialties to use depending on the board’s needs. Next, we’ll look at the factors PCB CMs consider when choosing a fabrication vendor to build your circuit board.
How to Determine the Best PCB Fabrication Vendor?
As we’ve seen above, there are different circuit board types, sizes, layer counts, complexities, and materials. PCB contract manufacturers will maintain a list of trusted fabrication vendors they use depending on the needs of the circuit board. In making their selection, the PCB CM will consider these factors:
- Capabilities: A large prototype backplane with multiple layers will typically need a different fabricator than one that specializes in large production runs of small double-sided boards. The CM understands this and will choose a fabricator accordingly from their pre-approved list of vendors.
- Quality: Circuit boards are broken into different classes depending on their application, and not all vendors can build to the rigorous standards of a class III board. These boards are typically used in mission-critical spaceflight or medical applications and cost more to fabricate due to their precision.
- Availability: There is more to availability than just an open spot in the queue. CMs have to evaluate the fabricator’s location, price, and customer service when choosing the best fabricator for a circuit board.
PCB contract manufacturers will occasionally have to qualify a new fabricator to build a circuit board that is not on their list. This circumstance could be due to capacity, lead time issues, or the circuit board requires different technology than what the standard vendors can build. In this case, the CM will go through a vetting process to ensure that the new vendor can produce the needed quality. And if the customer requests the CM to use their own approved PCB fabricator, that is usually not a problem as long as the vendor meets the CM’s requirements. This often leads to a new business relationship between the CM and the fabricator.
Having your PCB CM choose the fabrication vendor for your circuit board build has several advantages for the end-user. These advantages include better visibility into the pool of PCB fabricators and a richer understanding of the circuit board manufacturing industry to make the best choice. Additionally, the volume of work generated by a PCB CM often results in a lower price for bare board fabrication, and those savings will be passed along to the customer. Now let’s look at how you can work with your PCB CM to get the best fabricator for your project.
What Your PCB CM Needs from You to Choose the Best Fabricator
A PCB contract manufacturer has a lot of experience working with different fabricators, and they are in the best position to choose the right fabricator for your project. However, there are some things you can do that will help expedite this process and ensure that your boards will be built on time, on budget, and at the high levels of quality you expect:
- Work ahead with your PCB contract manufacturer to have all the necessary data at the beginning of the design. Not only will you be able to design to the correct layer stackup and material requirements, but the CM will have the information they need to line up the best fabricator.
- Make sure to submit complete manufacturing files when the design is completed. Too often, a file is left out of the package, or an older file is not updated with current design information. These oversights can slow the manufacturing process down considerably and introduce errors.
- Include clear and concise build instructions in the manufacturing files. Omitting details such as solder mask requirements will only slow down the process as the fabricator has to wait for the CM to retrieve that information from you.
If you aren’t sure about any of these details, ask your CM, and they will help you develop the correct manufacturing files and build instructions you need. At VSE, we have been helping our customers prepare their designs for fabrication and assembly for over 35 years. We know fabricators, and we understand how to help you prepare your design for error-free manufacturing.
