Analysis

Optimising designs for manufacture

4th June 2015
Phil Ling

Anthony Green, Director of Engineering Solutions - EMEA looks at how to get around the problems of pre-approved designs that are not production ready.

Today’s electronics manufacturers have evolved ahead their markets. I remember a not too distant past when a customer’s design would arrive, get checked, costed and kitted, and be passed onto the assembly line and then shipped back out x weeks later – job done. Now it is a very sophisticated process, especially in sectors such as aerospace and healthcare, where close collaboration between the customer and manufacturer is absolutely essential to drive the lowest total cost while achieving time-to-market targets.

In these sectors regulation and certification is king. Without it no product will make it onto the market. For the manufacturer though, the stage in the design through to manufacture process at which they become involved can make all the difference to the ease of its production.
In the aerospace industry the lifetime of a product is vast in comparison even to the med tech sector and it is the norm for a part to remain in service for twenty or thirty years. It is such an expensive and highly regulated process to bring a product to market that once operational it is likely to remain there. It is, therefore, essential that the development process is maximised to ensure the most efficient production schedule.
In an ideal world a customer will involve their manufacturer at the earliest possible stage in the design process, ensuring that the end design is the one best suited for production. With close collaboration from the concept stage its design team will be able to influence the customer’s design for optimum manufacturability too. The product will move from concept through prototyping to full production with both parties fully involved in the process, arriving on the market at the right time and right price.
In highly regulated industries, however, adaptation of designs is not always possible as many designs have already been submitted to the appropriate bodies and received full certification before the manufacturer has had view of the plans. Presented with the design a team then has to make sure that it will meet the demands of the manufacturing environment whilst maintaining the original elements that met the compliance requirements. There is often no going back to the drawing board at this stage.
In this situation the manufacturer has to look closely at what can be done during the commercialisation phase, looking how to transition those designs through to production. If they were put straight into production the chances are that there would be defects and manufacturing issues throughout the process that could potentially lead to quality challenges.
One way to overcome these challenges it is look at the design from a different angle by utilising the designing for excellence mind-set that is normally applied during the early stages of a product’s design and take that into the manufacturing environment. It is more manufacturing for design rather than design for manufacturing. In both avionics and med tech the inherent development costs are very high and you cannot afford to have any delays or problems during manufacture.
It is best practice, therefore, to alter the original design during the manufacturing stage rather than attempt to make changes earlier. By using design for excellence tools the team has the ability to optimise the manufacturing process, to look at where there are cost challenges and then identify what can be done to improve those. This all has to be accomplished whilst maintaining the original design that has already received approvals.
As an example, if a leaded part has 20 leads coming off it that need to be soldered onto a PCB, and it is in a dense technology section of the board, then those leads will need to be ‘a couple of zeros’ apart. The likelihood, though, is that it has not been designed in a way that allows for that space. This is an issue that would not have occurred if the customer and manufacturer had worked closely at the design stage.
Reviewing the design it becomes apparent that the pads are too close and that a high number of solder shorts will happen during the manufacturing process. Taking the design and looking at it from a manufacture for design angle the solution would be to add a solder mask, which will prevent the solder from flowing between those pads. It would also be essential to add in a specialist inspection after production to ensure that the part does not fail once it goes into use.
When developing for medtech products there are more opportunities for adjustments during a product’s lifetime than there is in avionics. In fact, future proofing is essential in today’s fast paced medical device market where upgrades need to be achieved both efficiently and simply. While some upgrades are purely a software modification there are some that may require hardware changes. This means that the designers need to look at the longer-term life of a product at an early stage in its development, as any upgrades to the hardware will also require certification. Even if it is not going to be utilised initially, getting the projected developments in place so that it passes verification and manufacturing tests will save time and money in the long term.
Turning a design that is not optimised for manufacture into one that will go through the production process, without compromising the original certified design, and with the minimum of delay and cost can be a challenge. However, by engaging early on with your manufacturer, taking the design and reviewing it from the end product backwards, and then applying manufacture for design principles, it is possible to deliver a fully functioning product on time and within budget.

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