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Advanced Packaging Gets an Additive Upgrade

Article by Dr. Art Wall, Director of Fab Operations, NextFlex

The recent approval of the CHIPS Act has reignited the U.S. semiconductor industry and shone a spotlight on the intricacies involved in chip manufacturing. As new technological innovations—such as 5G, IoT, AI, automotive and high-performance computing—come to market, they’re pushing chip manufacturing and integration capabilities. They demand more performance which leads to added complexity in an already extremely complicated process. All this requires a fundamental shift in the way that semiconductors are manufactured and integrated.

It’s no secret that many believe Moore’s Law, the standard basis for semiconductor innovation over the past 50 years, is reaching the end of its reign. With a need to continue shrinking the size of components, engineers are running into roadblocks based on the physical limitations of electronics manufacturing, packaging, and integration. As manufacturers, we’re tasked with finding new ways of improving electronics capabilities, specifically regarding speed and size.

One of the key strategic avenues that’s arisen is rethinking how we approach the packaging and integration of modern semiconductors. This has implications across the board for chip design, including how they are combined and how they communicate between the chips. Combining dissimilar chips into an integrated package, called heterogeneous integration, and including somewhat generic chip building blocks called chiplets, is quickly becoming necessary to keep pace with technology advancement.

Challenges in Traditional Packaging and Chip Interconnect

Printed circuit boards (PCBs) are the backbone of electronics, acting to connect integrated circuits (ICs) and discrete components to form a larger working circuit. Historically, individually packaged chips and components are mounted to a PCB and interconnected to deliver functionality.

Following this methodology, all the layers in a board act as separate interconnects, leaving the top and bottom of the board to place components. As the drive to miniaturize while simultaneously becoming more complex requires the addition of more components, this is where we’ll begin to see limitations.

An important part of the CHIPS Act was the recognition that not only does the United States need to make massive investments in chip-making facilities or foundries, but also to invest heavily in advanced packaging. Serving as the next step of combining or integrating these chips with novel approaches will be just as important in the innovation of U.S. semiconductor manufacturing capabilities. Some forms of this approach already exist through methodologies such as multi-chip modules or system-in-package (SIP), but more radical approaches are needed to deliver the required performance of the devices.

Advanced Packaging Landscape and Complementary Manufacturing Methods

Companies like Intel, Qorvo, Mercury, and Skywater are pushing the limits of integrating chips and chiplets through new approaches
to make chip-to-chip communication seamless. This provides many advantages in speed as well as miniaturization, but often requires
extremely sophisticated, complex, and expensive tools and processing. While this is critical and important to the next generation of electronics integration and packaging, an interconnect methodology has been developed that can provide complementary capabilities: additive electronics manufacturing.

We see additive manufacturing all around us in the form of 3D printing. But several organizations are actively working on a method to bring these additive and printing methodologies into the process of printing interconnects for electronics. This can enable manufacturers to now print circuits layer by layer, opening the door to new capabilities in interconnection and allowing for components to now be embedded within the PCB itself.

In a sense, this takes care of the conventional packaging steps of the manufacturing process because you can add the raw component within the layers of the board. As a result, we’ve begun
to see a blurring of the lines between chips, packages, and the printed circuit board, otherwise known as system level packaging.

With the combination of these new possibilities for component integration and printed interconnect process, we can see many advantages such as far fewer process steps, lower cost, less
waste, and rapid prototyping.

This will not replace the more expensive approaches for chip-to-chip integration entirely but can provide a complementary solution for the right applications. High-frequency applications are already taking advantage in some cases of chip stacking to improve both performance and miniaturization.

Additive Processing Applied to Printed Circuit Boards That Can Also Be Flexible

It’s easy to see the impact the inclusion of additive processes for electronic interconnects can play in advanced packaging, but this can also extend beyond and serve as an alternative to traditional PCB manufacturing. This would again take advantage of the faster and lower cost these methods provide.

Much of the materials, process, and tooling development in additive electronics comes from a technology referred to as flexible hybrid
electronics (FHE). This is a concept where the circuit board is additively printed on a low cost, flexible substrate and bare, unpackaged, thin, flexible chips are directly integrated onto the
printed traces. Flexible electronics have many applications such as medical wearable devices, asset monitoring, soft robotics, and more. Not only does this mean that electronic systems can be made flexible, but it also leads to a substantial reduction in weight, which is critically important in applications such as automotive
and aerospace.

The opportunities for what we can achieve in the development of chip manufacturing and traditional PCB processes following the signing of the CHIPS Act feel limitless. With this large emphasis placed on the role electronics play in our daily lives, we can begin innovating in new areas of the process, such as advanced
packaging, and implement the benefits of additive techniques.
The simplification of electronic board manufacturing has the potential to revolutionize PCB manufacturing while also continuing to impact the advanced packaging process. We just have to take the first steps to meet the advanced needs of incoming innovations.

Originally published in SMT007 Magazine, November 2022 issue.