This article is part of TechXchange: Chip Shortages and Counterfeits
What you'll learn:
- Taking a micro-carrier-card approach.
- Dual-footprint and secondary-component substitution design.
- What is a last-time buy?
We’re well into 2022, and at this point, supply-chain issues are still a challenge for those of us creating and sustaining existing products. In some ways, the current situation is no different from the pre-pandemic days when shortages of one component or another were a fact of life.
What remains unusual is the continuing, simultaneous shortages of multiple major and minor components in multiple categories. This adds new wrinkles to engineers’ jobs in creating new products and sustaining products already in the market.
A number of larger companies have been able to manage the supply crunch better than smaller or mid-size companies, but even some of them and their huge procurement organizations are struggling. Still, there are those like Tesla, according to a recent NY Times article, that are successfully dealing with the challenges (though a lot of details are kept secret at Tesla). A Reuters article talks about how Apple deals with supply-chain problems, partially through smart procurement.
Not to be overlooked, the way products are designed can have a big impact on mitigating supply-chain challenges. While the problems aligning supply and demand may improve within months or a few years, engineers still need to get product out the door now.
Here are some best practices in design to help minimize supply-chain issues:
1. Auxiliary micro carrier card
As designers, we hate to add in extra boards to a system. It has a negative impact on cost, but it may now be necessary. This requires a close look at support circuitry to accommodate more than one micro version or other parts in the product.
Such an approach results in flexibility and makes it possible to pivot as needed in response to flaky supply availability. Along with this method comes an impact on firmware that may now need to be “smart” enough or featured to accept alternate hardware.
The carrier-card approach helps get around problems where one can obtain the same part in multiple package variants. Using an existing PCB with a micro carrier card could offer an advantage in that the main board may have already gone through EMC testing or other regulatory certification processes.
2. Dual footprint design on single PCB systems
In some cases, it may be possible to find components in multiple package configurations. PCBs can be designed to accommodate multiple footprints. This particularly applies to alternate package variants of the same micro from a single vendor source. As with the carrier-card concept, firmware intelligence or adaptability may be necessary. Designing for flexibility is key.
3. Design for secondary component substitution
For secondary components, such as memory chips, look for similar parts with adaptability in the firmware to enable parts substitution based on available supply. Oftentimes, it’s important to pay special attention to drivers that can detect subtle differences between components. For example, one can design for the same function with slightly different pinout signals or pinout locations in the board pattern.
4. Accelerate to next generation
Not every product works with the latest and greatest chips. If you’re working with an older design, there could be end-of-life concerns. Of course, one can almost always do a last-time buy, but that’s a stopgap.
Supplies may be so short that there could be significantly long delays in getting material for a last-time buy. I use the words “almost always” here because the notice given for last-buys can be very short these days. In fact, there are times in the current environment when suppliers suddenly discontinue parts without the option for a last-time buy.
If it rains lemons, make lemonade. This might be the time to proactively advance to the next-generation chipset so that the product is adapting to parts that the chip manufacturers want to produce in volume. End-of-life components often are only available in low volumes to the product manufacturer. This can result in escalating cost or reluctance of the chip manufacturer to invest factory resources in producing a part if discontinuation is imminent.
5. Strip parts from evaluation boards
Stripping parts from evaluation boards is a desperation move that can be used in extreme cases. When parts are needed for development or low-volume early production, one can sometimes make the emergency case for purchasing evaluation boards, harvesting parts off those boards, and using them for an immediate need. In a crisis, necessity is the mother of invention.
6. Last-time and risk buys
Last, but not least, is the age-old practice of last-time and risk buying. These aren’t normal times. Today’s situation has resulted in companies stockpiling parts to a degree never practiced before, and it’s disrupting the normal market forces of supply and demand.
Take a careful look at supply; it may be advisable to procure well in advance of need. The risk, of course, is that the wrong parts or quantities may have been pre-ordered. Applying “engineering judgment” to the decision process can prove helpful in having the anticipated parts on hand when needed.
Today, it’s not unusual to see lead times of 50 to 100 weeks for parts. Even worse, one can’t always trust the lead times being quoted. Delivery times are routinely getting pushed out 30 to 40 weeks beyond those quoted at time of order. What used to be a minor checkbox of investigating parts availability and second sourcing has become a critical problem. Using some of the techniques previously described can help get you through this supply-chain crisis.
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