SIP Semiconductor Technology Overview

Key Takeaways

• SiP semiconductor technology offers a powerful solution for integrating multiple integrated circuits within a single package, 

• Differentiating SiPs from other packaging styles, such as SoCs and MCMs, is crucial. While SiPs offer a lower level of integration compared to SoCs, they excel in their ability to create complete systems in a single package

• SiPs provide several advantages, including shorter time-to-market, reduced assembly and test costs, improved electrical performance, and simplified PCB layouts. 

SiP Semiconductors can enable better and more efficient designs.

SiP semiconductor technology revolutionizes the integration of multiple integrated circuits, allowing for the creation of compact and highly functional electronic systems. By combining various chips within one or more chip carrier packages, SiP offers a versatile approach to system design. With advancements in packaging techniques such as package-on-package, 2.5D and 3D-ICs, and flip-chips, SiP semiconductors have gained prominence in applications ranging from mobile phones to digital music players. In this article, we will delve into the intricacies of SiP semiconductor technology, exploring its advantages, differences from other packaging styles, interconnection methods, and the challenges associated with its development.

What is SiP Semiconductor

A system in a package (SiP) refers to the integration of multiple integrated circuits within one or more chip carrier packages, allowing for stacking using the package-on-package technique. SiP semiconductors are capable of performing a majority, if not all, of the functions of an electronic system. It is commonly employed in the design of components for mobile phones, digital music players, and similar devices.

SiP Semiconductor Technology Overview

SiP semiconductor dies offer the flexibility of being stacked vertically or tiled horizontally using techniques such as chiplets or quilt packaging. In SiPs, the connection between the dies is established through standard off-chip wire bonds or solder bumps. In contrast, slightly denser three-dimensional integrated circuits employ conductors that run through the stacked silicon dies to establish connectivity.

SiPs have the capability to incorporate multiple chips within a single package. These chips can include:

• Specialized processors
• DRAM
• Flash memory
• Passive components like resistors and capacitors. 

All of these components are mounted on the same substrate. As a result, it becomes possible to create a complete functional unit within a multi-chip package, reducing the need for additional external components to make it operational.

To achieve vertical stacking, dies containing integrated circuits can be placed on top of each other on a substrate. These dies are internally connected by fine wires that are bonded to the package. Alternatively, in flip chip technology, solder bumps are utilized to join the stacked chips together. SiPs share similarities with systems on a chip (SoCs) but are less tightly integrated and do not rely on a single semiconductor die.

SiP vs SoC

SiPs and SoCs are two different integrated circuit architectures with distinct characteristics. In the case of SoCs, components based on function are integrated into a single circuit die. This results in a highly integrated solution where all the required electronic elements are contained within a single chip.

On the other hand, SiPs take a different approach by connecting modules as discrete components within one or more chip carrier packages. This architecture resembles the traditional motherboard-based PC architecture, where components are separated based on function and connected through a central interfacing circuit board.

In terms of integration, SiPs have a lower level of integration compared to SoCs. While a SoC encompasses all the necessary electronic elements within a single chip, a SiP consists of individual chips accommodated within one package, each serving a specific functionality.

SiP vs MCM 

Heterogeneous integration can take various forms, including chiplet-based designs, multi-chip modules (MCMs), and system in package (SiP). Defining these packaging styles can be challenging, as there are overlapping features and different terminologies used by different suppliers. However, some distinctions can be made between them.

The primary difference between an MCM and a SiP lies in their scope and functionality. While an MCM does not necessarily have to be a complete system, a SiP is designed to be a system in a single package. A SiP integrates multiple integrated circuits (ICs) along with supporting passive devices into a unified package. In contrast, an MCM represents a tightly coupled subsystem or module packaged together. It may not encompass the entire system's functionality but serves as a cohesive unit.

SiP Semiconductor Design and Packaging Notes

SiP semiconductor solutions incorporate multiple packaging technologies, including flip chip, wire bonding, and wafer-level packaging, among others. In recent years, there has been significant progress in improving SiP through advancements like 2.5D and 3D-ICs, package-on-package, and flip-chips. Several factors are driving these changes.

Firstly, analog intellectual property (IP) doesn't scale as easily as digital circuits across different process nodes, making it challenging and costly to migrate IC designs in accordance with Moore's Law. The ability to shrink the digital portions while keeping analog at older process geometries is increasingly appealing, but it requires sophisticated communication between dies.

Secondly, as features shrink and more functionality is added to semiconductors, the length and thickness of wires increase, resulting in longer signal propagation times within a chip. By packaging different chips together, interconnected through an interposer or through-silicon via (TSV), signals can be accelerated by reducing wire distances and widening conduits.

Thirdly, the demand for extended battery life in mobile devices necessitates reducing power consumption for signal transmission. Shortening signal travel distances, particularly to and from memory, and widening conduits have a direct impact on energy efficiency.

SIP Interconnection

In the manufacturing of SiP semiconductors, wire bonding or bumping technologies are typically employed for interconnection. The assembly process itself poses a challenge for SiP manufacturing. It requires the ability to horizontally and vertically assemble and interconnect multiple dies. Die stacking, where multiple dies are placed on top of each other, is extensively utilized in state-of-the-art SiP manufacturing, earning SiP the moniker of "3-D package."

Flip chip bonding is another interconnection method used in SiPs, either independently or in conjunction with wire bonding. Flip chip configuration can be applied to either the upper or lower dies, depending on the design intent. Directly flip-chipping a bottom die onto the substrate allows for high-speed operation, while flip-chipping a top die eliminates the need for long wires to connect to the substrate.

SiP Advantages and Disadvantages

In addition to shorter time-to-market, SIP semiconductor manufacturing offers various advantages.

• One notable benefit is the reduction in overall assembly and test costs, as only one package needs to be assembled and tested to create the system. 

• SIPs contribute to improved electrical performance due to the shorter interconnections within the package. 

• Another advantage is the simplification of the final application module assembly process, as SIPs require simpler PCB layouts. This is possible because the complex interconnections required by the system are already handled inside the SIP. 

• Other advantages include miniaturization, cost reduction, yield and manufacturability, reliability, and antenna integration capabilities. 

Effective heat dissipation is a crucial challenge in SiP development. Commercially available chips designed to dissipate heat through their own packages may pose difficulties when incorporated into SiPs. Crowding multiple chips together within a SiP can lead to significant heat accumulation, requiring careful thermal management throughout the SiP semiconductor development process.

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