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72 SMT007 MAGAZINE I NOVEMBER 2018 The companies that come to mind for wear- able, medical devices are all the big ones already doing it—Fitbit, Nike's wearable divi- sion, etc. There are some known companies as well as some startups, which are making some medical devices. Amongst the numerous start- ups, and most of them are making devices for monitoring, diagnosis, and analysis. The appli- cations that everybody knows and works with right now include physical exertions, number of steps taken, calories burned, flights of stairs climbed, heart rate, and more. These products are way beyond us now. The product that we're dealing with today is a medi- cal device that you wear on your wrist, and it has sensors that will monitor the chemical composition of your body fluids. It has propri- etary algorithms where if there's a specific change in the composition of chemicals in your body fluids occurs, it will alert you and or your doctor in real time. For example, if your blood sugar goes too low, the device will warn you that you should start driving to a hospi- tal because it's probable that you will have a medical incident in the next 30 minutes (e.g., stroke, heart attack, etc.). These devices are becoming more predictive of medical condi- tions that may occur in humans. Soon, we will have devices that alert you to call 911 and say, "I'm going to have a medical issue within the hour, please send an ambulance." Due to miniaturization, another challenge we see in medical devices is the need for a new set of tools to be able to do bonding— wedge, ball, or ribbon bonding—and inspect and provide qualitative evidence because these devices are so small you can barely see and make anything out of the images through regular human eyes. You need a sophisticated inspection tool that will provide measurements of the curve of a wire bond in microns (e.g., ±5 to ±10 microns) to be able to see if that will run through the amount of current that the device requires. Thus, specialized tools are required for bond- ing and inspection methodologies that can look at loops, curves, bends, and height. You also need to provide evidence that it will with- stand the test of time. Sometimes, you find that it's a bottom-terminated device—like your fine BGA—but you need to do underfill to make the device sturdier. Sometimes with underfill- ing materials, such as a membrane-like mate- rial, you have to control the thickness under- neath the device so that it will adhere to your mechanical dimension requirements. These are some of the challenges in assembly. You have covered a lot of flex circuitry in the past couple of issues of your magazine, so when it comes fabricating portable, hand- held, and wearable devices, you marry rigid with flex for PCBs. This brings additional challenges when trying to bond between the two. To be able to place certain components on the rigid side versus flex, and make sure the current flows through properly—and in some cases where the board needs to be bent— you have to calculate the bend radius. There are specific challenges that are now coming into the picture because of the change in tech- nology. Las Marias: The increase in the manufactur- ing of medical devices is driving growth in the use of flex printed circuits. You also mentioned challenges when dealing with medical elec- Figure 2: Wire bonding.