Understanding the true costs of design failures

Author : Tom Gregory, Product Manager, 6SigmaET

02 January 2019

6SigmaET

For today’s design engineers, balancing power, heat and performance is ever more difficult. In particular, as devices become increasingly complex, compact and ‘smart’, with more and more sensing capabilities, intelligence and connectivity built in, thermal performance rises in importance, since excessive heat can lead to higher failure rates.

This article was originally featured in the January 2019 issue of EPDT magazine. Sign up to receive your own copy.

As such, there is a far greater focus on the thermal management of devices. But while overheating is certainly a major issue for modern devices, its effects are not always immediately observable – and certainly not always predictable. As a result, Tom Gregory, Product Manager at engineering simulation software specialists, 6SigmaET explains, the importance of, and reliance upon, thermal simulation software during the design process has increased.

Despite this growing importance, for many engineers, there is still some resistance to using thermal simulation software. 6SigmaET’s own in-depth research (summarised in its ‘State of Thermal’ report, available online at 6sigmaet.info/et-why-switch/) shows that while a quarter of engineers simulate their designs before producing any physical prototypes, 13% of engineers don’t test the thermal performance of their designs at all. This flies in the face of the fact that one in five engineers specifically identified thermal issues as a common cause of design delays.

Cost headaches

One of the biggest sources of resistance to simulation is undoubtedly cost. The same research found that one in four thermal engineers are dissatisfied with the cost of their current simulation package. It would be foolish to ignore the cost of simulation tools. A typical thermal simulation software licence may cost between £7,000 and £15,000 per year.

Of course, this seems like a big number when viewed in isolation. However, the value of simulation is in enabling engineers to test their devices much earlier in the design process – reducing the possibility of failures further down the line. And as every engineering team knows, failures, particularly late in the design flow, often mean going back to the drawing board – investing yet more time and money in finding and correcting the flaw.

The question then becomes: what exactly is the cost of thermal failures? And does avoiding such design failures offset the cost of the simulation software? In essence, what is the return on investment for thermal simulation?

Breaking down the cost of a design failure

Typically, a late stage failure will be identified once a prototype has been produced and undergone physical testing. Correcting that failure is a process that involves going back to the original design, identifying and addressing the causes of the failure, building a new prototype and then testing the revised design to ensure the fixes have been successful.

The severity of the failure will determine just how much work that process will entail, but we estimate an average time for respinning a design and preparing a new prototype for retesting in this way is two weeks – although this could vary considerably based on the product and the design change

involved.

ET case

Perhaps unsurprisingly, the largest cost involved will often be time, and the extra hours your engineering team will need to put in. The average day rate for an electronics engineer will vary from £500 to £1,000, so for a two week respin you are looking at approximately £5,000 to £10,000 of cost, just in terms of engineering time – assuming it is a relatively simple failure that can be fixed by one person. The costs could be significantly higher if changes are required to multiple parts of the system design.

On top of the design costs, there are also the costs associated with producing a new prototype. There are a few different elements involved here, but the key costs are:

•  PCB costs – depending on the complexity of the PCB involved, producing a small run of 10 test modules may cost between £2,000 and £3,000.

•  Enclosure costs – creating a new enclosure for the updated prototype will also cost £2,000 to £3,000.

•  Assembly costs – for small runs of prototypes, you are probably looking at using a technician to assemble the devices by hand. This could take two to three days, at a cost of £200 per day.

Finally, there is the cost of repeating the environmental testing. Most prototypes won’t overheat when operating in 20ºC on your testbench – you need to test its performance at the extremes of temperature. As a result, environmental testing is crucial. Putting your prototype through its paces in an environmental test chamber can cost upwards of £1,000 per day.

Even working on the conservative end of these estimates, you are looking at a single failure easily costing as much as £10,000 to put right. With only a few extra complications, it could easily rise to well over £20,000. That’s not just a waste of money – it’s also a waste of your engineering resources, that could be more usefully deployed elsewhere and on other projects (opportunity cost).

Understanding the true costs of design failures

Of course, this also assumes that late stage failures are a relatively rare occurrence. But 6SigmaET’s survey of electronics engineers reveals that 99.5% of engineers have had a product derailed by late stage complications. One in twenty engineers admit that every single project they work on experiences delays caused by failures.

To take a more conservative average again, we might expect a design team to experience two or three failures in a typical year. Suddenly £10,000 or £20,000 becomes £30,000 or £60,000. Simulation can help prevent much of that waste, representing a minimum of a 50% cost saving (on the software licence) over the course of a year.

When thinking about the ‘costs’ involved in thermal simulation, it’s important to not just think in terms immediate monetary costs for the software licence, but rather to consider the overall return on investment for your project in the long-term. While it’s easy to dismiss thermal design as ‘low priority’, the truth is that considering thermal issues earlier on in the design process is essential for ensuring a product is right first time – helping minimise the wasted money and effort that come with design failures.


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