Issue link: https://iconnect007.uberflip.com/i/1047182
NOVEMBER 2018 I SMT007 MAGAZINE 71 smaller devices with less footprint and real estate, challenges start to come. Regarding physical packages, a couple of years ago, a physical passive package was 0201 for capac- itors and resistors, which is very challeng- ing, but most people were able to handle that. But then a smaller package entered the picture: 01005, which is half the size of a 0201 passive device package. Now, the 01005 pack- age physically speaking, is essentially a speck of salt or pepper, which you can barely see, let alone manufacture, inspect, and ensure that you installed it properly and it's functioning correctly. When it comes to active devices like BGAs—which used to have 0.5-mm pitch a few years ago, but have now dropped to 0.4, 0.3, 0.25, 0.2 mm (and will soon be 0.15 mm pitch) —it becomes challeng- ing because you also do not have the luxury of real estate on the board itself. You used to running two traces between the pads of the BGA when doing the layout for a medical device in the days of 0.5-mm pitches, but now you're talking about 0.2 mm, so you're barely able to running one trace out of the two between the two pads during layout, and that will probably be two or three mils at most. These are very fine traces, which would possi- bly limit the fabricators because not everybody can successfully manufacture with a 2 mils trace going from one place to another. This is the new challenge, which needs to be properly addressed as well. What's happening now is you are creeping into the microelectronics world when it comes to medical devices. Now, you remove the pack- aging—glass, plastic, or ceramic based—from the component—such as a resistor, IC, or whatever the case may be—and placing these components directly onto the substrate or PCB. What happens is the traditional surface-mount manufacturing cannot handle that, and manu- facturing companies and contract manufactur- ers must have special capabilities to handle those. Why? Because when you're placing these components directly on the substrate or PCB, you need to have specific devices, and a specific environment and manpower to do that kind of manufacturing. When you're wire bond- ing, wedge bonding, or ball bonding in micro- electronics to produce medical devices, you have to have a clean room—Class 10,000 or 1,000—because you're dealing with very fine components without packaging, so you need to control the dust, debris, and contamination within the room where you're manufacturing the medical product. In traditional SMT, you don't need a cleanroom as long as you are controlling the humid- ity and the temperature, but not in the case of microelec- tronics. Not only do you need the clean room, but you also need specific machines— such as a wire bonder, wedge bonder, and shear strength testing device—and you also need specific micro dispens- ing capabilities because of the major difference between traditional SMT manufactur- ing and microelectronics—size. In traditional SMT manufacturing, we do the design and discuss items in mils, which is a hundredth of an inch, but in microelectronics, you talk in microns. You have to place the devices with the toler- ance in microns to measure and inspect them, and in some cases, even calculate the loop of the wire bondage you are putting together to a specific wire bonder that you have in place. Then you need devices with the shear or pull strength measurements to make sure the device can withstand the force of the product (phys- ical exertions, mechanical vibrations, rugged environments, etc.). Microelectronics are not new, but they are a relatively new beast where everything is moving, and the medical indus- try is not immune to that. Zulki Khan