MEDICAL ELECTRONICS
The challenge Composed of many sequential processes to produce complete electrical or photonic circuits on semiconductor wafers, wafer fabrication plants are very expensive to maintain, and in a bid to reduce costs, some companies have, in recent years, taken the decision to shelve complete production lines. When one of their suppliers announced the decision to discontinue its entire production line of optoelectronic sensors, our customer faced a supplier gap that needed to be bridged. However, this would prove to be extremely
challenging. The customer needed to source replacement sensors that were ‘like for like’ both mechanically and electronically. If they didn’t, they would most likely have to conduct lengthy and costly re-verification and re-validation processes due to the stringent industry requirements and regulations that exist. This challenge was exacerbated due to the limitations of their own internal engineering and R&D teams. Focused predominantly on developing new product designs, the team lacked the bandwidth to deal with obsolescence issues and needed to turn to its partner network for support. Although the customer was able to buy
remaining stock from the supplier to bridge the gap in the short term, they were keen to find replacement sensors through a new partner, rather than tying up thousands of dollars of stock that, if not used, could degrade and become unusable, creating unnecessary financial liabilities.
The solution Taking on a project like this, we firstly needed to understand the obsolete products and how those products were used within the context of the medical applications. Although we couldn’t source any technical data directly from the supplier, the customer was able to share their own technical specifications they had created, allowing us
to understand the top-level performance characteristics we needed to align with. We then needed to consider and review
particular aspects of the application that could not change, as well as aspects that could be tweaked before making a decision as to whether or not we could design a like for like replacement that would align with the customer’s requirements and be commercially viable. With no specific technical detail on the individual components, we had to source suitable alternatives that would provide a similar function and output under the same operating conditions. From the design perspective, there was no
3D model to work from; therefore we had to look at all parts of the mechanical and electronic design in order to design our own housings. This included all parts of the process, the equipment, as well as specific areas such as injection mould tooling, this was an opportunity to deep dive into the
internal structure and look at how we might design a more effective solution and improve the reliability and robustness. In one example, the switch was originally
manufactured by soldering wires directly onto the leads of the optical devices. In a very tight space, this can lead to short circuits and other long-term reliability complications. We changed the internal design to a solution based on a very small PCB and standard production practices. This led to a more robust and reliable product, which was much easier to build. It is far more effective to solder multiple discrete optical components into a panel of PCBs using a flow solder process, than to rely on manually soldering wires to each leg of the discretes. We also had to develop plastic housing for
a transmissive IR switch. When we tested the switch separately, it functioned as we would expect, but when the switch was inserted into the application, we noticed that there was a light source in the equipment that is used for a diagnostic test that was flooding the switch and causing it to change state. We had to alter the design and use an opaque-to-IR plastic to ensure it functioned correctly.
Results Improved reliability has led to yield improvements not only for the customer but also within our own internal production process, at a realistic level that allows us to continue to produce the parts. Ultimately, this project was focused on providing a 100% drop-in replacement that meant the customer didn’t have to change anything within the machines to allow it to work. As well as delivering this objective, a number of “bonus” design improvements were identified, developed and implemented along the way, resulting in an even better product.
Pacer International
www.pacer.co.uk
OCTOBER 2021 | ELECTRONICS TODAY 27
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