Is there anything worse than having a complete electronics design that can’t be built because one of its components has a 52-week lead time?
I work for an electronics manufacturer. We’ve been building small and medium volume PCB assembly runs since 2003. Back in 2018, my company started getting serious warnings from components suppliers about an impending state of extreme shortages. And this was before the COVID-19 pandemic and its accompanying disruption in labor and transportation.
I don’t think I’ve ever seen a components market this messed up. At any given time, there can be a hundred different projects in our factory in the process of being built. I won’t give you an exact percentage that are waiting for long-lead parts, but it’s a lot.
You may think that, as a manufacturer, I’m just at the end of the cycle and don’t have much to say about the rest of the process, but that’s really not the case. The sooner you involve your manufacturing partner, the better off you will be, especially for high-volume boards. We, and others like us, can give you thoughts on what to avoid doing and what to do to help navigate messed-up supply chains.
Avoid questionable substitutions
Be wary of finding subs from the gray market or brokers. When desperation takes hold, the lure of the gray market can be overpowering. Resist this, or at least do as much vetting as you can. I’ve seen brokers and less than legitimate sellers rack prices up 10X, 50X or even more.
Another problem with sketchy vendors is in counterfeit or re-labeled parts. For example, you may get a completely different component that has been relabeled. Alternatively, you may receive the correct or similar part, but from the manufacturer’s reject bin. The first device may test out okay, but how many will later fail in test or in the field?
“The same, only different,” does not mean equal
If you pick a functional equivalent, double check the pinout. This is probably the most common issue we see with last minute substitutions. A good example would be a three terminal voltage regulator issue, as in the LM1085 low drop out (LDO) regulator. It looks, for all intents and purposes, to be a standard three-terminal pin-out part. You’d look at it and assume that it’s a direct replacement for any old three-terminal regulator. But, rather than the common In-Ground-Out, the 1085 is pinned as Ground-Out-In.
I ran into another case not long ago with a GPS module. The replacement part was functionally equivalent with the original, but the pinout was mirrored. The only difference in the part numbers was a “C” added to the part number suffix on the version we were given as a substitution. The parts look identical in form fit and function, but one used top view part numbering, with pin one in the standard upper left, while the other had pin one in the upper left when looking at the part from a bottom view.
Close may not be close enough
Subs that are close, but not exact, may cause support issues later. I’m a long-time fan of microcontrollers, but there is one aspect that has always bothered me. That’s the inability to use a more capable chip in place of a lessor chip without needing to make a change either in the header software, the configuration bits, or both.
A good example would be a Microchip PIC18F43K22. It’s got 36 GPIOs, a good set of peripherals, 8K of Flash, and 512 SRAM bytes. That’s plenty of code space for the electronic “bubble” level I designed a while back. I built my prototypes with the PIC18F44K22. It’s an identical part, except with more Flash and SRAM.
When it came time to build a higher volume run, the low-end parts weren’t available, so I used a variant with more Flash. All of those parts would have been fine, but each required different configuration bits and code header details. That meant that I couldn’t just publish a hex file and upgrade any and all of them later. Although this is an easy hardware sub, it may cause software challenges later on.
Get to know your supply chain partners very well
Manufacturing and components sourcing has never been something that should be isolated from design, but today, with the messed-up supply chain, the sooner an engineer starts looking at parts selection options the better.
The most important thing for you, as a design engineer or project manager, is to become a close partner with the supply chain folks at your manufacturer. Design for manufacturing has long brought the assembly line and design engineering together. Now is the time to also invite procurement into the process.
Your supply chain folks live every day in the world of shortages, alternates, and promised lead times. They will have the best view on lead times and the small and large quantities availability.
Designing for “wait or change”
Back in the days when “shortage” meant a couple of extra days or weeks, the standard response was to search other distributors or find someone that overbought and had enough extra to get you through. When manufacturers tell you that they won’t even accept an expedited request until after the 52 week “standard” lead time has passed, you might need to take a different approach.
If you’ve got a super long-lead time component without an easy sub, do you wait and hope against hope that somehow it will come in early? Alternatively, do you revise the design to use a different component or component set? This can be especially painful with new chips that consolidate multiple functions or passives into the silicon. Creating a new revision of the design may mean a larger PCB and a higher bill of materials (BOM) line-item count. On the other hand, a rev can mean the difference between getting your product to market next quarter vs. next year. Consider the impact of a year’s delay when deciding on a three-component solution vs. a fancy new highly integrated part that you just can’t get your hands on.
The supply chain will eventually catch up and allow us to pick parts based on specifications rather than on availability, but we probably have another year or more before that happens. If we all learn to live in this different world, then the process of getting our products out of the door will become a little bit easier and less stressful.