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74 PCB007 MAGAZINE I JULY 2018 Amides, such as polyimide, are one such ma- terial. Amides and imides are the least reac- tive of the carboxylic acid derivatives. How- ever, they are attacked by strong base and acid (heat). Base hydrolysis of an amide is shown in Figure 3 using 1M KOH at 80°C for 20 minutes, followed by 0.2N HCl at RT for five minutes. It is highly recommended that this type of procedure be implemented when attempting to metalize polyimide. This is referred to as a pre- conditioning step. Successful metalization of flex and rigid-flex board structures is challenging. However, if one understands the limitations of the wet pro- cesses (never assume you can apply FR-4 pro- cessing here), a void-free continuous adherent copper deposit is achievable. A few additional caveats: • Not all electroless copper processes perform equally • Plasma leaves the surface in an inert state, which is not easy to obtain adhesion and coverage • Pay attention to the pre-plating parameters and tighten the operating window as needed • Flex and rigid-flex is "not your father's FR-4" anymore Michael Carano is VP of technology and business development for RBP Chemical Technology. To reach Carano, or read past columns, click here. For every three individuals who have had a stent im- planted to keep clogged arteries open and prevent a heart attack, at least one will experience restenosis—the renewed narrowing of the artery due to plaque buildup or scarring—leading to additional complications. Now, a team led by UBC electrical and computer engi- neering professor Kenichi Takahata has developed a type of "smart stent" that monitors even subtle changes in the flow of blood through the artery, detecting the narrowing in its earliest stages and making early diagnosis and treatment possible. "We modified a stent to function as a minia- ture antenna and added a special micro-sen- sor that we developed to continuously track blood flow. The data can then be sent wireless- ly to an external reader, providing constant- ly updated information on the artery's condi- tion," said Takahata. The device uses medical-grade stainless steel and looks like most commercial stents. Researchers say it's the first angioplasty- ready smart stent—it can be implanted using current medical procedures without modifica- tions. Research collaborator Dr. York Hsiang, a UBC professor of surgery and a vascular surgeon at Smart Stent Detects Narrowing of Arteries Vancouver General Hospital, noted that monitoring for re- stenosis is critical in managing heart disease. "X-rays such as CT or diagnostic angiograms, which are the standard tools for diagnosis, can be impractical or inconvenient for the patient," said Hsiang. "Putting a smart stent in place of a standard one can enable physi- cians to monitor their patient's health more easily and of- fer treatment sooner."