CircuiTree - September 2008 - (Page 42)

PCB and Package Convergence A lthough it’s been rather quiet lately, the constantly asked and seemingly charged question on the future of PCB has been whether PCB and chip design will merge into a single technology or not. This time I will steer clear of that question and instead look at the convergence of package and PCB—a convergence that has deﬁnitely occurred. There are three main aspects of this convergence. We can look at circuit technology convergence, we can look at design methodology convergence, and we can look at organizational convergence. In this article we will look at all aspects. stream, but just a few years later, microvia and HDI were picked up at a much faster rate. For obvious reasons, designers try to stay with conservative technology—well-proven designs and high yield give low cost and less risk. In recent years, market forces are especially driving demand for higher levels of integration, forcing some companies to adopt advanced board technologies to meet their business needs. When this happens, the technologies being used are typically the same that are being used in the IC packaging world. In fact, Hewlett Packard designed PCBs for its products decades ago that still challenge what is possible, even for package design. Technology Convergence PCBs have been around longer than most are aware of. There are patents on PCB-like technology as far back as the ﬁrst years of the 20th century, but real circuit boards ﬁrst came to use during World War II as the result of an effort by the Austrian engineer Paul Eisler to dramatically shrink the size of the ceramic, solder turret-style vacuum tube designs of the time. Function and area density requirements have clearly been a technology driver since the beginning of time! Since the introduction, we have seen a steady development toward a denser, more complex circuit board. About 20 years ago, multilayers became the dominant board type in the world. I’m sure we can agree that the pace at which PCB technology evolves becomes faster and faster. For example, the trace width and spacing we regard as mainstream today was practically impossible to manufacture 20 years ago. Surface mount technology took time to become main42 September 2008 • circuitree.com Package Evolution Where did packaging come from? The IC packages we have today have little in common with the simple packages or thin/thick ﬁlm hybrids that were designed in the ‘70s. Just as for PC boards, there has been a strong and steady development of new technology but the PCB technology and the packaging technology has been—and still is—driven by completely different roadmaps. While many of the technologies are similar, the packaging roadmap is driven by the silicon roadmap and very little by PCB requirements. Likewise, the PCB roadmap is driven by PCB interconnect requirements and very little from silicon design requirements. This leads to different paths for the two, but the one common requirement of increased component and wiring density has led to designs with a clear convergence. Bare die or CSP assembly on PCB is being applied as a http://circuitree.com

Table of Contents Feed for the Digital Edition of CircuiTree - September 2008

CircuiTree - September 2008 Contents My Line Industry Review Tech Talk Flexible Thinking New Halogen-Free Materials: Their Time Has Finally Arrived Asian Section IPC Issues PCB and Package Convergence Ask the Flexperts Market Outlook IPCA Showcase Technical Product Spotlights Classified Ads Upcoming Events Ad Index

CircuiTree - September 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.