Feature: Interconnections


The Occam process steps


Achieving lower- cost, higher- performance and more-reliable electronics


By the Occam technical team T


he ability to manufacture better products at lower cost has been the objective of all industries since the dawn of the industrial age – better performance, better reliability, better features, and so on. The electronics industry has made steady improvements in its design


and manufacturing processes over time, but there have been few “step function” improvement breakthroughs. Most astute electronic designers of today are well aware


of the many problems that beset manufacturing engineers tasked with turning their visions into reality. Open circuits, short circuits, thermal damage to PCBs and components during assembly, multiple design spins to deal with signal integrity and noise issues – the list goes on. How can we address all these problems simultaneously – and, is it even possible?


30 May 2023 www.electronicsworld.co.uk


Figure 1: A highly simplified graphic illustrating the basic Occam process variant where two QFN (quad flat no-lead package) devices are interconnected by plating the interconnections with copper and using an aluminum carrier base to provide dimensional stability and thermal management


Electronic assembly through the ages Electronic manufacturing has been wedded to the soldering process for many decades. However, modern electronic devices and design practices are stretching soldering technology to its limits, as component pincounts continue to rise and lead pitches shrink. Before the advent of surface mount technology (SMT), through-


hole leaded components dominated electronics. Design and manufacture were simple, but size, performance and cost of the parts remained wanting. SMT was conceived at about the same time as dual in-line


packaging (DIP), which proved challenging from an assembly perspective, since most PCBs were assembled by hand. In the early 1980s, SMT took off and machines and processes


gave the technology the boost it needed, especially since it came with improved performance, size, cost and speed of assembly. Tere was an explosion of innovation in component design and process equipment, as engineers tried to address the many previously unseen and unknown problems that accompanied SMT. DIP was replaced by a myriad of new packages like SOT,


TSOP, QFP and more, with gull wing leads, J-leads, beam leads, castellated leads, and so on. Each combination brought its own assembly challenges, and yet all were being assembled onto the common PCB. Tese packages were soon joined by ball grid arrays, land grid arrays, QFNs and, eventually, chip scale


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