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First, we asked you to send in your questions for Happy Holden. Now, it’s Joe Fjelstad’s turn! Inventor, columnist, instructor, and founder of Verdant Electronics, Joe has been involved with rigid PCBs and flexible circuits for decades, and he’s ready to share some of his knowledge with our readers. We hope you enjoy “Just Ask Joe.”
Q: Is the Occam process an early version of chiplets, placing chips first in assembly?
A: There have been a number of speculative and prospective chip first package solutions over the last 15–20 or more years. GE, Intel, and others have shown ways of interconnecting chips in packages by plating and then socketing or surface mounting the resulting components on PCBs using solder as almost everything still is today.
Chiplets are a more recent manifestation where chips are tiled and interconnected in mosaic form around the edges using solder. Occam was envisioned as a way to eliminate solder from the manufacturing process by reversing the manufacturing process. That is, building a “component board” comprised ideally of packaged ICs, all having a common grid pitch for terminations and which have been tested and burned in. Circuits are then built up onto the component board as if it was a basic PCB substrate. The component board substrate can be of almost any material because soldering is not required. Aluminum is suggested because it is an excellent thermal conductor and has a CTE near that of copper. Having all components with a common grid makes routing very efficient, and layer counts can drop significantly. Because there is no soldering, there is no unintended thermal damage to components or assembly. With the reduced number of steps, the assemblies should be much less expensive.
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Joe Fjelstad is founder and CEO of Verdant Electronics and an international authority and innovator in the field of electronic interconnection and packaging technologies with more than 185 patents issued or pending. To read past "Flexible Thinking" columns or contact Fjelstad, click here. Download your free copy of Fjelstad’s book Flexible Circuit Technology, 4th Edition, and watch the micro webinar series on flexible circuit technology.