This is no way intended to be comprehensive DFM advise, but more of a short list of things we commonly see in day-to-day contract manufacturing that can often save time and money for all stakeholders.
It is with no doubt the continual evolution of EDA design tools such as Altium has helped design engineers produce consistently better CAM outputs for their manufacturing partners. Regardless, there is always a human element that can contribute to early success, or the contrary.
Here are a few suggestions that may help someone effect more expert outcomes, more often.
Component selection
Reducing the overall amount of BOM lines will save you money. Period. Things such as pull up resistors and decoupling capacitors are normally low hanging fruit, but sometimes there is a hidden gem. Each BOM item that is rationalized is one less item to purchase and kit, one less SMT feeder to setup, potentially less freight, one less stock line to count at stock-take etc. Another often overlooked outcome of BOM rationalization is reduced overall MOQ (minimum order quantity) cost exposure, and better quantity price breaks.
Bill of Materials clarity
The BOM is your manufacturers master purchasing list and master board population guide. It should be a meticulously prepared document and critically reviewed before issue. Ensure part numbers are complete and accurate with the manufacturer listed for each part. If a part can be generic then say so on the BOM. List all of your DNF components in a uniform manner and ensure designators are correct if manual editing has been done. Once issued to your manufacturer, it is critical revision control is exercised without exception. Last but not least, don’t forget to put sundry items such as nuts, screws, insulators etc. on the BOM if you want it fitted or supplied.
Design for availability
There is no better time to use design for availability principles than now and I don’t mean checking stock at online distributors. You need to consider the manufacturers lead time as online stock is often a case of “now you see it, now you don’t”. It only takes one part with a 70+ week lead-time to derail your product launch. Consider specifying at least two alternatives for every critical item (wherever possible) in your design and make sure they are detailed in your BOM.
Reduce the number of manufacturing processes
Sometimes you can’t avoid working with very small areas and you have to cram components into small flexible circuits, but most of the time we find there are costs to be saved with some minor tweaks. As an example, adding SMT components to the second side of the PCB means adding another entire process. Another setup, another 1st article inspection, another SPI, another AOI, so on and so forth. In short, minimize processes. Reducing the overall number of processes (even moving that one cheeky PTH capacitor to the top side) can save a bucket of money. This is often a great conversation to have with your manufacturer at an early stage in the design process. I need all of my fingers and toes to count the number of processes required in some builds and the costs add up quickly.
Think about testing
Make adding test points a standard practice to your PCB layout tasks. Even better, make adding all of your test points to just one side of the PCB a standard practice. The time to do it is before you assemble your first prototype. Nothing quells the excitement of going to manufacture more than not having an answer to the inevitable question “what have you planned for testing”? Make the test points as large as practical. It will make an aging test jig perform better and save on false negatives and jig maintenance. If you are supplying a test jig to your manufacturer, consider if it will pass a risk assessment once it arrives. Will it be deemed safe, or a shock hazard? And remember, a basic test is better than no test at all.
There is a lot to add to this discussion and each design will have its own nuances.
With a South Australian HQ and two Australian owned manufacturing plants, we have over 350 staff. Servicing everyone from tech start-ups to multinational companies, Entech specialises in full turn-key contract electronics manufacturing, including PCB Assembly and complex sub-assemblies / complete devices. Now with 1000+ successfully completed products over 36+ years, we have a lot of Design for Manufacturing knowledge that can benefit your next design.
Reach out to us today and ask how we can add tangible value to your new product manufacturing experience.
