From 2020 to 2021, there has been a worldwide shortage of integrated circuit (IC) supply, resulting in a heightened importance of ICs. This shortage has driven advancements in miniaturization, low power consumption, intelligence, and high reliability in electronic components. As a result, the integrated circuit industry has witnessed rapid growth in recent years.
One crucial aspect of modern ICs is their packaging, which, similar to the circuit boards they connect to, necessitates specialized substrates. Therefore, it is crucial to understand the significance of IC packaging substrates as integral components of integrated circuit structures. This guide aims to delve into IC packaging substrates and the manufacturing and application processes employed by manufacturers, from the perspective of a circuit board engineer.
Overview of IC Substrate Market
From a semiconductor manufacturing process perspective, the integrated circuit industry chain can be divided into three key elements: design, manufacturing, and packaging and testing, in a top-down approach. Packaging and testing involve the conversion of tested wafers from the midstream process into independent chips, serving as a vital assurance for the industry chain.
Integrated circuit substrates, known as IC substrates, encompass advanced packaging (AP), flip chip scale package baseband (FC CSP), 5G wireless equipment, high-performance computing (HPC), graphics processing units (GPUs), servers, and FC BGA in the automotive industry. The market value of IC substrates is predicted to grow from 12.6 billion USD in 2021 to 24.3 billion USD in 2027, with a compound annual growth rate (CAGR) of 12%.
Substrate-level printed circuit boards (SLP), primarily utilized in high-end smartphones, generated a revenue of 3 billion USD in 2021 and are projected to reach 4.3 billion USD in 2027, with a CAGR of 6.7%. Embedded die (ED) in laminate substrates is a relatively new technology in the market and is anticipated to experience substantial growth, with a CAGR of 39%, reaching 1 billion USD in 2027 from 142 million USD in 2021.
The primary technology trend in substrates lies in the adoption of semi-additive process (SAP), modified SAP (mSAP), or advanced mSAP (amSAP). In recent years, SLP technology has maintained a stable development, while the objective of ED technology is to enable multi-chip embedding for broader application possibilities.
What is IC Carrier Board (IC Substrate)?
Firstly, let us briefly discuss what an IC packaging substrate is.
The IC packaging substrate, also known as an IC carrier board, has evolved from the related technologies of PCB boards. It serves the purpose of establishing signal connections between ICs and PCBs, as well as providing circuit protection, wire fixation, and heat dissipation.
In the mid-1990s, a new form of high-density IC packaging emerged, represented by ball grid array (BGA) and chip-scale packaging. It was during this time that the IC packaging substrate came into existence.
In essence, an IC packaging substrate is a critical base material for advanced packaging of integrated circuits—a “special” type of PCB. As a high-end PCB, the IC packaging substrate exhibits characteristics such as high density, high precision, miniaturization, and thinness.
In the realm of advanced packaging, IC packaging substrates have replaced traditional lead frames and become an indispensable part of chip packaging. They not only provide support, heat dissipation, and protection for the chips but also establish electronic connections between the chips and the PCB motherboards, playing a pivotal role in bridging the two.
Significantly, almost all aspects involved in the packaging of integrated circuits are carried out on or related to IC packaging substrates.
Among the four fundamental technologies in electronic packaging engineering—namely, thin and thick film technology, micro-interconnection technology, substrate technology, and encapsulation and packaging technology—the substrate technology holds a critical and central position.
With the emergence of new high-density packaging forms, many functions in electronic packaging, such as electrical connections, physical protection, stress mitigation, moisture and heat dissipation, dimensional transitions, standardization, and specification, are gradually being undertaken partially or entirely by the packaging substrate.
Moreover, IC packaging substrates can even embed passive and active components to achieve certain system functionalities.
What’s Materials Used to Make IC Substrate?
IC packaging substrates can be broadly categorized into three types based on the different materials used:
1. Rigid Substrates:
The main materials used are BT (Bismaleimide Triazine), ABF (Ajinomoto Build-up Film), and MIS (Molded Interconnect Substrate). These substrates find extensive applications in high-end chips such as communication and memory chips, LED chips, CPUs, GPUs, chipsets, as well as in markets like analog, power ICs, and digital currencies.
2. Flexible Substrates:
The main materials used are PI (Polyimide) and PE (Polyester). Flexible substrates are primarily employed in automotive electronics, consumer electronics, and military applications such as carrier rockets, cruise missiles, and space satellites.
3. Ceramic Substrates:
The main materials used are alumina, aluminum nitride, and silicon carbide. Ceramic substrates are utilized in various fields including semiconductor lighting, laser and optical communication, aerospace, automotive electronics, and deep-sea drilling.
These different types of IC packaging substrates cater to diverse industry requirements and offer unique characteristics suited for specific applications.
IC Sustrate Manufacturing Technonlogy
Integrated Circuit (IC) substrate manufacturing technology refers to the process of fabricating the substrates on which integrated circuits are built. IC substrates provide a foundation for mounting and interconnecting various electronic components, including semiconductor chips, within an integrated circuit package. The technology involved in IC substrate manufacturing has evolved over the years to accommodate the increasing complexity and miniaturization of integrated circuits.
Here are some key aspects of IC substrate manufacturing technology:
1. Substrate Materials: IC substrates are typically made from materials like ceramics (such as alumina or aluminum nitride), organic laminates, or high-density interconnect (HDI) substrates. The choice of substrate material depends on factors such as electrical performance, thermal management, cost, and manufacturing capabilities.
2. Substrate Fabrication: The fabrication process starts with the preparation of the substrate material, which involves shaping it into the desired form and size. This can be done using techniques like casting, pressing, or laser cutting. After shaping, the substrate may undergo processes like surface treatment, cleaning, and metallization to enhance its electrical and mechanical properties.
3. Circuit Formation: Once the substrate is prepared, circuit patterns are created on its surface using various techniques. The most common method is through printed circuit board (PCB) manufacturing processes, including photolithography, etching, and deposition of conductive and insulating layers. These processes define the interconnections and electrical routing paths for the integrated circuits.
4. Packaging and Interconnection: After circuit formation, the integrated circuits (chips) are attached to the substrate using techniques like wire bonding or flip-chip bonding. Wire bonding involves using thin wires to connect the chip’s pads to the substrate’s corresponding pads. Flip-chip bonding involves directly attaching the chip’s solder bumps to the substrate’s pads. These bonding techniques provide electrical connections between the chip and the substrate.
5. Testing and Quality Control: Once the chips are attached, the substrate undergoes various testing procedures to ensure the functionality and reliability of the integrated circuits. These tests may include electrical testing, thermal testing, and other reliability assessments. Quality control measures are implemented throughout the manufacturing process to identify and rectify any defects or inconsistencies.
IC substrate manufacturing technology continues to advance to meet the demands of more advanced integrated circuit designs. The industry is constantly striving for improvements in substrate materials, fabrication processes, interconnection techniques, and testing methodologies to enable higher-performance integrated circuits with smaller form factors.
IC Substrates Characteristics
IC substrates, also known as PCBs (Printed Circuit Boards), possess various characteristics and features. Some of these include:
1. Lightweight: IC substrates are generally lightweight due to the use of thin materials. This characteristic is advantageous for portable electronic devices and applications where weight reduction is crucial.
2. High Reliability: IC substrates form a protective layer around the integrated circuits, ensuring their reliable operation. As a result, they are constructed using solid materials that provide stability and protection against environmental factors.
3. Reduced Wiring and Soldering: IC substrates typically have smaller dimensions compared to typical PCBs. Consequently, they require fewer wiring connections and soldering points, allowing for more compact designs and efficient use of space.
4. Compact Design: IC substrates are designed to be compact, taking into account the miniaturization of electronic components. This design approach allows for the use of less material for packaging and enables the integration of complex circuitry in a confined space.
5. Durability: Despite their often small size, IC substrates are engineered to be durable and robust. They are designed to withstand mechanical stress, temperature variations, and other environmental factors, ensuring their longevity and reliability.
These characteristics make IC substrates suitable for a wide range of applications, where lightweight, reliable, and compact designs are essential. The specific attributes and features of IC substrates may vary depending on the intended application and the requirements of the integrated circuits being packaged.
Classification of IC Substrates
IC substrates come in various types and can be classified into three main categories: package/package type, bonding technology, and material properties/characteristics. Additionally, they can be further categorized based on their application domains.
Package Types: Each package may require different types of substrates.
BGA Substrates: These substrates are suitable for IC packages with a large number of pins (>300). They are primarily attributed to their excellent electrical performance and heat dissipation capabilities.
Chip-Scale Package (CSP) IC Substrates: These substrates are characterized by their miniaturized and thin form factor. Hence, they are suitable for small-sized single-chip packages with fewer pins.
Flip Chip IC Substrates: This type of substrate is best suited for controlled collapse chip connection in flip chip package (FCCSP). It offers good heat dissipation protection, preventing circuit losses and signal interference.
Multi-Chip Module (MCM) IC Substrates: These substrates house multiple ICs in the package, and each IC may have different functionalities. Therefore, the substrate material needs to be lightweight. However, due to the characteristics of MCM ICs, such substrates may lack sound signal integrity, proper routing, or efficient heat dissipation.
These different types of IC substrates cater to the specific requirements of different package types and applications, ensuring optimal performance and functionality.
IC Substrate Applications
IC substrates find extensive applications in various areas, including:
1. Memory Chip Packaging:
IC substrates are used in the packaging of memory chips, such as dynamic random-access memory (DRAM) and flash memory. These substrates provide the necessary electrical connections and support for reliable data storage and retrieval.
2. Microelectromechanical Systems (MEMS) Packaging:
IC substrates play a vital role in packaging MEMS devices, which are used in sensors, actuators, and other micro-scale mechanical systems. These substrates ensure proper electrical connections and mechanical stability for MEMS components.
3. Radio Frequency (RF) Chip Packaging:
IC substrates are utilized in the packaging of RF chips, which are crucial for wireless communication systems. These substrates enable efficient transmission and reception of RF signals while maintaining signal integrity and minimizing interference.
4. Processor Chip Packaging:
IC substrates are employed in the packaging of processors, which are the central computing units of electronic devices. These substrates provide the necessary circuitry and connectivity for the processor to function optimally.
5. Integrated Circuit Packaging in High-Speed Communication Devices:
IC substrates are used in the packaging of integrated circuits in high-speed communication equipment, such as routers, switches, and optical communication systems. These substrates support high-speed data transmission, signal processing, and network connectivity.
These IC substrates can be found in a wide range of electronic products, including:
Smartphones and Tablets:
IC substrates are integral components in smartphones, tablets, and other smart devices, enabling their computing power, memory storage, and wireless connectivity.
Laptops, Printers, and Memory Products (e.g., RAM Modules):
IC substrates are utilized in laptops, printers, and memory products to enable data processing, printing functionality, and efficient memory storage.
Medical Devices:
IC substrates are incorporated into medical devices, supporting their diagnostic capabilities, patient monitoring, and precise control of medical equipment.
Telecommunications, Aerospace and Defense, Industrial Machinery:
IC substrates are used in various industries, including telecommunications infrastructure, aerospace and defense systems, and industrial machinery. These substrates enable reliable communication, signal processing, and control in these sectors.
The utilization of IC substrates in these applications ensures the efficient and reliable operation of electronic products across diverse industries.
IC Substrates, Substrate-Like PCB, HDI PCB and Standard PCB: Difference
IC substrates are typically designed with 2-10 layers, substrates-Like PCB also is 2-10Layer. HDI (High-Density Interconnect) boards, range from 4-16 layers, while standard PCBs can have over 100 layers.
There are variations in the thickness of different substrate types. IC substrates are the thinnest, usually below 1.5mm, with some going as thin as 0.1mm. SLP (Substrate-Like PCB) is thicker than IC substrates, HDI is thicker than SLP, and the thickest PCBs can exceed 7mm in thickness.
One of the most important parameters is the line width and spacing (the width and distance between internal traces). IC substrates typically have line widths below 25μm (1mil), SLP substrates are above 1mil, HDI is around 2mil, and standard PCBs are above 2mil.
Now, let’s dive deeper into SLP, which falls between IC substrates and HDI, and explore its technical parameters. SLP (Substrate-Like PCB) allows for a reduction in line width and spacing from HDI’s 40/50μm to 20/35μm, with the minimum line width and spacing reaching below 30μm in SLP.
From a manufacturing perspective, SLP is closer to IC substrates used in semiconductor packaging but hasn’t reached the specifications of IC substrates. Its purpose is still to accommodate various active and passive components, making it part of the PCB category.
The Future of IC SubstrateBoard Industry
The demand for PCBs in the electronic industry continues to expand, but the high-end PCB industry, led by IC substrates, is still largely dominated by foreign companies. However, there is a notable trend of the global PCB industry shifting towards mainland China.
It is foreseeable that with China’s advantages in labor costs and the accumulation of experience and technological expertise in the IC industry over the years, domestic companies may gradually take over the assembly and testing business that has been transferred from Japan, South Korea, and Taiwan.
Currently, leading domestic PCB companies in mainland China, such as Shennan Circuits and JarnisTech Technology, have already established large-scale production capabilities for IC substrates. Although their market share is still relatively low, they have broken the technological monopoly of foreign companies in the substrate field, achieving significant breakthroughs.
This shift in the PCB industry to China signifies a significant milestone, as it showcases the country’s potential to become a major player in the high-end PCB market. With continued investment in research and development, infrastructure, and talent, domestic companies have the opportunity to further enhance their capabilities and competitiveness in the global PCB industry.
Conclusion
IC substrates have revolutionized the field of electronics integration, enabling the development of compact and highly efficient electronic devices. As the demand for advanced electronics continues to grow, IC substrates have become indispensable components in the industry.
While the high-end PCB market has been dominated by foreign companies, there is a notable shift towards mainland China, where domestic companies are gradually gaining momentum in IC substrate production. With their scale and capabilities, these companies are breaking the technological monopoly and positioning China as a significant player in the global PCB industry. As we look ahead, IC substrates will continue to play a vital role in driving innovation and enabling the seamless integration of diverse electronic components, paving the way for the next generation of advanced electronic devices.
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