The PCB manufacturing and assembly world is all about turnover. The more projects that are lined up for production, the more likely an assembly house can keep their doors open. This creates a temptation for many houses to sacrifice quality in the name of reduced lead times. The best manufacturers, however, will take the time to understand your design before putting your board into production.
Design review takes some time, especially for a high-layer-count, high-net-count PCB. Anytime design problems are spotted, your manufacturer must engage in back-and-forth communication with you, the customer, to fix these design problems. In the worst case, a CM will have to send the design back to you for changes. The key to ensuring quick turnaround PCB assembly time is to anticipate these potential problems through early communication.
Quick Turnaround PCB Assembly Is All About Communication
Whether you need to produce a small number of prototypes or you need to scale to a larger order, quick turnaround PCB assembly is all about communication. Simpler designs that obey typical design rules may make it through the manufacturing process without much more communication than uploading your design files and signing a quote sheet. However, not all manufacturers can produce complex designs for advanced devices. If you can gather information in the following areas before beginning your design, you can reduce the time required to send your board into fabrication and keep yields high.
1. Communicate Early and Often
Do you know how many PCB designs get put on hold before they enter the assembly line? If you guessed “all of them,” then you’re basically correct. What is the most common reason designs get put on hold? The design team didn’t look into the manufacturer’s capabilities, component inventory or lead time for a quick turnaround PCB assembly order.
Something as simple as a phone call or email when beginning a layout can help you get a better idea of lead time, available components and materials, and DFM requirements for a new board.
Neglecting to take these factors into account can force a redesign or can increase lead times for assembly. If you can gather information on these points early, then you can avoid redesigns and ensure your board gets into production faster.
2. Get to Know Your Assembler’s Capabilities
Simple design choices, like spacing between thermal vias in a thermal pad, use of thermal reliefs near large copper pour regions, silkscreen placement, and solder mask thickness, can create major quality problems if your assembler can’t accommodate these design choices. The first two of these design choices can cause your design to receive a no-bid status from your manufacturer. Meanwhile, most assemblers can easily accommodate these design choices without sacrificing quality.
Are the vias in this thermal pad too close together? Your manufacturer can help you determine the right spacing between these vias to prevent solder wicking.
The PCB manufacturing business is all about turnover, and the company only makes a profit when there are more boards on the assembly line. Some low-volume manufacturers increase your risk of defects by putting your design directly into production without spotting design choices that can decrease yield. An experienced manufacturer should be able to spot instructions that will ruin a board with a simple check of a customer’s Gerber files and Excellon/NC Drill files. If you fully understand your manufacturer’s capabilities, you can spot these design problems and keep your turnaround time low.
3. Don’t Give Your Manufacturer More Than They Can Handle
If you need quick turnaround PCB assembly services, ensure your board house can accommodate your schedule and has the bandwidth to accommodate your order size. CMs that specialize in quick turnaround PCB assembly and prototyping have developed their processes to accommodate high-mix, low-volume manufacturing and can quickly get your board into production after a design review.
4. Make Your Testing Requirements Clear
A bare-board test is used to compare a manufactured board to the original Gerber Data. To ensure your testing requirements are clear, you should rely on more than just using your Gerber data. This is where you should send a netlist to your manufacturer along with your Gerber data.
The IPC-D-356 netlist format can be used to compare a schematic netlist to your board’s Gerber data. This comparison should be performed before a manufacturing and assembly job is started to ensure there are no discrepancies. This test can increase the NRE charge, but it helps a CM catch errors early, rather than catching errors after the final assembly. At VSE, our quick turnaround PCB assembly services are ideal for prototyping and producing low-volume manufacturing runs. We specialize in low-volume, high-mix manufacturing to get your NPI off the ground. Additionally, our design review and engineering change request processes help to perfect your design so it can be scaled when you are ready to do so.
