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20 PCB007 MAGAZINE I JUNE 2021 temperature on resistance. Reducing the tem- perature allows the conductor to carry more current in relation to the cross-sectional area. However, there is self-heating proportional to I2R. It is normal to use a lookup table of ac- ceptable temperature increase related to cur- rent and conductor area. e use of special thermally conductive di- electrics such as Ventec VT-5A2 or VT-4A2H could help to reduce the temperature and in- crease your traces' maximum current capabil- ity. Going a step further, IMS materials could also extend the window by helping with heat dissipation. However, this is not always a suit- able solution. A serious shortage of copper, for any reason, could change things by driving up prices. en you need to consider the cost and practicalities of introducing the alternative material to your manufacturing processes, and how soon the copper price may return to normal. PCB007 Kim Sauer is global marketing communications of Ventec International Group. I would like to add a brief comment re- garding one additional option available, albeit on a limited basis and for specific application areas. Herb Neuhaus and I devel- oped a technique based on nano-particle ther- mo-compression to mount optical compo- nents with very high I/O counts on pitches as fine as 12–15 microns. In our program we em- ployed various nano-Ag compositions devel- oped/targeted for die attach applications, the most useful of which was a formulation from Nihon Superior out of Osaka, Japan. ey did do some customization of the particle size mix and distribution, but the process is quite stable in these high pin count applications. While our approach was developed and de- ployed specifically for mounting bare chips onto ceramic substrates in these applications, omas Brunschwiler at IBM Zurich picked up on the idea and extended it to PWB assem- bly employing Cu nano-particle formulations developed in Europe. I have not spoken with omas recently, but he did present a keynote talk at the Pan Pacific Microelectronics Sym- posium in 2017 in which he briefly described their work. I believe that the work was com- pleted in late 2018 or early 2019, but I have not followed up or searched for any publications. I do know that the work was part of a doctor- al dissertation for a student being advised by omas. PCB007 Charles Bauer works for TechLead Corporation in Portland, Oregon. Beyond solder, what's the next best interconnection between the components and the PCB? A Q

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