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FEBRUARY 2020 I SMT007 MAGAZINE 75 ally any electronics industry journal or maga- zine, and you will find a substantial percentage of them devoted to solders; fluxes; soldering equipment; solder process improvement; fault identification, detection, and avoidance; and rework and repair. How can such a complex process with so many steps and pitfalls ever be considered truly reliable? In contrast, when solder is eliminated from the process, things arguably get much simpler. Moreover, a lead- ing cause of electronics failure is bypassed. Now consider the following: An electronic assembly where the fully tested and burned components with their terminations all on a common lead pitch are bonded to an alumi- num substrate (a close CTE match to copper and the CTE of engineered components) and encapsulated in the structure with the circuits and copper via interconnection all on the upper surfaces (Figure 1). Shock, vibration, and drop test reliability concerns largely evaporate. Who has ever seen circuits shaken off of the surface a circuit board?) When completed, the assembly can be plated with metal (excluding I/O required for connection to the outside world), making the assembly virtually hermetic and ESD and EMI immune (Figure 4). It also provides additional thermal spreading capability. Summary What has been described is different than what is currently being done but not impos- sible. The infrastructure, materials, and processes exist. What is missing is a will- ingness to try a new approach. Two ques- tions that are invariably asked are, "What about test?" and "How do you rework and repair?" The answer to both questions is basically the same and perhaps best answered in the Socratic method by ask- ing those two questions in reverse. That is "Why do you need to test?" and "Why do you need to rework and repair?" Testing is important in process devel- opment but ideally should not be needed in production where it provides no value. The same also for rework and repair. These steps should not be required if the right approaches to manufacturing are used, and the processes are done right. In other words, first do the right things, and then do those things right. Think about it. In conclusion, here is offered some solace for those whose livelihoods are tied to solder and soldering. Solder will be in use long into the foreseeable future in the same way that leg- acy packages, such as the venerable dual-in- line package (DIP), are still used today. There is a flywheel effect to every established tech- nology. Certain people around the globe still make buggy whips to this day. There are also ways for solder to continue to play a role in the manufacturing of advanced electronics and construction of packages much as it is pres- ently being used in the creation of 2D and 3D modules, which could well be adapted to sol- derless assembly in the future. It is simply a matter of choice and will. "Only those who will risk going too far can possibly find out how far one can go." – T. S. Eliot SMT007 Joe Fjelstad is founder and CEO of Verdant Electronics and an international authority and inno- vator in the field of electronic interconnection and packaging technologies with more than 185 patents issued or pending. Figure 4: Occam assembly offers the potential provision of an integral full metal jacket (exclusive of I/O access features) of the completed assembly to provide near full hermetic protection along with EMI and ESD immunity.

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