The Influence of Quantum Computing on the PCB Sector

As a frontier area in the field of science and technology, quantum computing has witnessed rapid development in recent years, demonstrating great potential to break through the limits of traditional computing. It is expected to trigger revolutionary changes in numerous fields such as cryptography, drug research and development, financial risk assessment, and materials science. Printed Circuit Boards (PCBs) are crucial components in the hardware systems of quantum computing, undertaking core functions like signal transmission, power distribution, and component connection. They play an indispensable role in ensuring the stable operation of quantum computers and realizing efficient computing. As quantum computing technology gradually moves towards practical application, the demand for high-performance and high-reliability PCBs is growing exponentially.

A thorough analysis of the PCB requirements in quantum computing not only helps optimize the design and manufacturing of existing quantum computers, enhance system performance and stability but also opens up new growth paths for the PCB industry, guides the direction of technological innovation, and promotes the integrated development across disciplines. This study aims to comprehensively and systematically explore the special requirements of quantum computing for PCBs in terms of technical specifications, material properties, and manufacturing processes, as well as the profound impact of these requirements on the PCB industry pattern and supply chain ecosystem, providing valuable decision-making references for relevant practitioners, researchers, and investors.

This report comprehensively employs multiple research methods to strive for comprehensiveness and accuracy in the research. Literature research covers academic papers, industry reports, and patent documents in the fields of quantum computing and PCB technology, sorting out the development context and cutting-edge achievements of the technology. Case analysis selects typical quantum computing projects and PCB enterprises to deeply explore actual needs and application practices. Expert interviews invite quantum computing hardware experts and PCB engineers to obtain first-hand professional insights and fill research blind spots.

The research focuses on the direct application of PCBs in the hardware systems of quantum computing, comprehensively analyzing the unique requirements of each link from qubit manipulation, low-temperature control circuits to data transmission and processing modules. Meanwhile, it pays attention to how the evolution of PCB technology feeds back to the development of quantum computing and expands the research boundary to the linkage of upstream and downstream industries, providing a comprehensive perspective for industrial development.

Quantum computing operates based on the unique principles of quantum mechanics, which are quite different from the traditional computing mode. The qubit, as the core information unit, breaks through the limitation that a classical bit can only take 0 or 1. Relying on the quantum superposition property, it can be in a superposition state of 0 and 1 simultaneously and can be precisely represented by a quantum state vector, such as (), where  and  are complex numbers and satisfy (). This means that a single qubit can carry far more information than a classical bit, laying the foundation for parallel computing.

Quantum gates are the key means to manipulate the states of qubits. Analogous to classical logic gates manipulating bits, they act on qubits through unitary transformation matrices to achieve complex operations such as rotation and flip, constructing quantum circuits to execute specific algorithm tasks. For example, the common Hadamard gate (H gate) can prepare qubits into an equal-probability superposition state, and the CNOT gate can flip the target bit according to the state of the control bit, precisely manipulating the entanglement and information flow between qubits.

Quantum algorithms make full use of the characteristics of qubits and quantum gates and demonstrate powerful computing power. Taking the Shor algorithm as an example, for the problem of factoring large numbers into prime factors, the computational complexity of traditional algorithms increases exponentially with the number of digits. However, the Shor algorithm, with the help of quantum parallelism, can efficiently solve the problem in polynomial time, posing a significant impact on the existing encryption systems. The Grover search algorithm can achieve a square root level acceleration in searching in unordered databases, greatly improving the search efficiency. Compared with classical computing, when dealing with specific complex problems, quantum computing can avoid the exponential time bottleneck of traditional computing by virtue of the natural parallel processing ability of quantum states and achieve a leap in computing efficiency.

The development history of quantum computing has been magnificent. Since its theoretical germination in the 1980s, after decades of hard work, it has entered a period of rapid technological iteration. Early explorations focused on theoretical construction and basic physical implementation. Systems such as nuclear magnetic resonance, superconducting Josephson junctions, and ion traps have successively become test beds for qubit manipulation, gradually overcoming difficulties in quantum state preparation, measurement, and manipulation.

Currently, technology giants and scientific research institutions are leading the trend in the industry. In 2019, Google launched the Sycamore chip, which contains 53 superconducting qubits and achieved quantum supremacy, performing specific tasks far beyond supercomputers. IBM has been continuously deepening its efforts. Its quantum computers have been opened to the outside world for cloud access, allowing researchers to test algorithms. The Eagle chip launched by IBM integrates 127 qubits and is steadily moving towards practical application. Intel takes advantage of the silicon-based semiconductor process to build low-temperature qubit chips and promotes the integration architecture of quantum and classical computing. Microsoft has taken a different approach by exploring topological quantum computing, striving to build a more stable and scalable qubit system.

Looking to the future, quantum computing will continue to make breakthroughs in multiple dimensions. At the hardware level, the number of qubits will increase exponentially, moving towards the scale of thousands or even tens of thousands of qubits. Meanwhile, the coherence time of qubits will be increased, and the error rate will be reduced to achieve large-scale and high-precision quantum error correction, providing solid computing power support for complex tasks. In the field of software algorithms, dedicated quantum algorithms will be developed for applications such as financial risk simulation, precise molecular dynamics simulation, and logistics route optimization, collaborating and complementing with classical algorithms to release the potential of quantum computing. In terms of industrial applications, quantum computing will be deeply integrated into medical and pharmaceutical fields, accelerating the drug research and development process, revolutionizing the models of financial risk assessment and investment strategy optimization, helping materials science to precisely design new materials, and promoting changes in the training paradigm of artificial intelligence, becoming a key tool for solving difficult problems in various industries and opening a new chapter of technological and industrial transformation.

In the quantum computing system, PCBs play a crucial role in building the “highway” for signal transmission, ensuring the accurate and stable transmission of various key signals such as qubit manipulation signals and measurement feedback signals. Taking Amphenol RF as an example, a series of its products such as high-frequency coaxial connectors, conformable cable assemblies, and miniature PCB connectors are widely used in the hardware architecture of quantum computing. For instance, the ultra-small push-on (SMP) high-frequency PCB connector interface, specially designed for board-to-board connections in quantum computing with limited space, has an extended frequency range of up to 40 GHz. The three-piece board-to-board connector can be blindly inserted, enabling efficient and reliable connection of different PCB modules in a narrow space and ensuring that the qubit manipulation signals are accurately transmitted from the control unit to the quantum chip, laying the foundation for the precise regulation of the quantum state.

The high-frequency and high-speed signal transmission in quantum computing imposes strict requirements on PCBs. As the manipulation frequency of qubits increases, the transmission lines need to have ultra-low loss characteristics to reduce signal attenuation and ensure that the operation instructions of quantum gates are completely delivered. Common high-frequency PCB materials, such as polytetrafluoroethylene (PTFE) substrates, have a dielectric constant (Dk) as low as about 2.2 and a very small dielectric loss factor (Df), which can effectively reduce the energy loss of signals during transmission and maintain signal integrity. At the same time, the impedance matching of the transmission lines should be precisely controlled. According to different transmission line structures such as microstrip lines and striplines, combined with the parameters of the materials, the line width, line spacing, and dielectric thickness should be carefully designed to keep the impedance stable near the standard values of 50Ω or 75Ω, avoiding the interference caused by signal reflection and ensuring the signal quality for complex operations such as qubit state switching and quantum entanglement generation, providing strong support for the efficient execution of quantum algorithms.

Quantum computing often needs to operate in an extremely low-temperature environment (at the level of millikelvin), which brings huge challenges to PCB interconnection. Low temperatures cause materials to become brittle and shrink, and conventional interconnection materials and processes are prone to connection failure and a sharp increase in contact resistance. Amphenol RF addresses this through material innovation. It uses special alloys such as beryllium copper (BeCu) to make connector contacts, which can still maintain good elasticity and electrical conductivity at low temperatures. It also optimizes the connector structure by designing redundant contact points and flexible buffer structures to compensate for material shrinkage and ensure the reliability of connections at low temperatures. In the connection between low-temperature quantum control chips and external measurement and control systems, these anti-low-temperature interconnection solutions ensure the stable transmission of signals, avoid the interruption of quantum computing caused by interconnection failures, and safeguard the long-term stable operation of the quantum system.

PCBs serve as the integrated “skeleton” of quantum computing hardware, integrating various electronic components and chips into an organic whole to realize complex functions such as the execution of quantum algorithms, control logic, and measurement feedback. Taking the qubit manipulation circuit as an example, multiple functional modules such as the signal input circuit, control pulse generation circuit, and readout amplification circuit rely on PCBs to achieve electrical connection and collaborative work. In a typical quantum computing experimental platform, a multi-layer PCB board integrates key chips such as digital-to-analog converters (DACs), field-programmable gate arrays (FPGAs), and radio frequency amplifiers. Through carefully designed wiring layers, the qubit control signals are accurately distributed from the source to each qubit, and the measurement signals are transmitted back to the data acquisition system without loss, realizing the fully automated control of the preparation, manipulation, and measurement of the quantum state and providing a hardware foundation for the operation of quantum algorithms.

When integrating qubit manipulation circuits on PCBs, difficulties such as complex wiring and sensitivity to electromagnetic interference are encountered. To precisely manipulate qubits, dense and high-precision control lines need to be laid on the PCBs. For example, the manipulation of a single qubit gate requires multiple independent control lines to adjust the amplitude, phase, and frequency of microwave pulses. This requires PCBs to have an ultra-high wiring density, with the line width and line spacing refined to the level of tens of micrometers. Meanwhile, a multi-layer board structure should be adopted, and the signal layer, ground layer, and power layer should be rationally planned. The ground layer should be used for shielding to reduce crosstalk between control lines. The grounding design should follow the principle of single-point grounding or multi-point grounding. The grounding path should be optimized according to the signal frequency to reduce the grounding loop and ensure that qubits are free from external electromagnetic noise interference, stably maintain the quantum state, and improve the fidelity of quantum computing.

The quantum measurement and control system relies on PCBs to integrate various functional modules to achieve precise monitoring and regulation of the states of qubits. In the quantum computing measurement and control board, a PCB board integrates modules such as microwave sources, power amplifiers, mixers, and filters, transforming the original driving signals into high-precision microwave pulse sequences that meet the requirements of qubit manipulation through multi-stage amplification, frequency conversion, and noise filtering. For example, by optimizing the PCB layout, the signal transmission path can be shortened, reducing transmission loss and delay. High-performance radio frequency materials can be used to improve the signal transmission bandwidth and phase stability, ensuring the high precision of the driving signals in terms of frequency, amplitude, and phase, meeting the requirements for the rapid and precise manipulation of qubits and providing precise measurement and control support for complex tasks such as quantum error correction and quantum algorithm verification.

The characteristics of high-frequency and high-speed signal transmission in quantum computing determine its strict requirements for the loss of PCB materials. Traditional FR-4 materials have a significant increase in dielectric loss in the high-frequency band (such as at the GHz level), and the signal attenuation is serious, making it difficult to meet the requirement for the accurate transmission of qubit manipulation signals. Taking the RO4000 series high-frequency materials of Rogers Company as an example, the typical value of its dielectric constant (Dk) is about 3.38 – 3.66, and the dielectric loss factor (Df) is as low as 0.0027 – 0.0037 at 10 GHz. Compared with FR-4, there is an order of magnitude improvement. The FR408HR material of Isola Company has a stable Dk in the range of 3.8 – 4.0, and Df is also controlled at a relatively low level in the high frequency, which can effectively reduce the signal transmission loss, ensure the high-fidelity transmission of quantum state regulation instructions and measurement feedback signals, reduce the misjudgment of qubits and the deviation of algorithm execution caused by signal attenuation, and lay a solid foundation for the stable operation of quantum computing.

Quantum computing often operates in an extremely low-temperature environment (close to absolute zero), and the performance of conventional PCB materials deteriorates at low temperatures. For example, ordinary epoxy glass fiber substrates shrink and become brittle at low temperatures, and the interconnection reliability drops sharply. Moreover, the change in thermal conductivity at low temperatures affects heat dissipation. Polyimide (PI) materials stand out. They have excellent low-temperature resistance characteristics, maintaining flexibility, mechanical strength, and electrical insulation at the liquid helium temperature (-269℃). The coefficient of thermal expansion is as low as (2 – 3)×10⁻⁵/℃, close to that of silicon-based chips, which can effectively avoid thermal mismatch. Its good chemical stability and low hygroscopicity prevent short circuits caused by the condensation of water vapor at low temperatures, ensuring the long-term reliable operation of the quantum control circuit in extreme low temperatures and making it the best choice for the substrate of PCBs in quantum computing.

The manipulation precision of qubits is advancing towards the sub-micron or even nanometer scale, requiring the wiring precision of PCBs to be adapted accordingly. In the connection area between the quantum chip and the measurement and control circuit, the line width and line spacing need to be refined to a few micrometers, which is difficult to achieve with the precision of traditional PCB manufacturing processes. Laser Direct Imaging (LDI) technology has emerged. Compared with traditional lithography, it can achieve fine wiring with a line width as low as 5μm by virtue of a shorter wavelength light source, with a positioning accuracy of ±1μm, ensuring the precise layout of qubit control lines. For the processing of micro-blind holes and buried holes, laser drilling technology has obvious advantages. It can drill through holes with a diameter of tens of micrometers on thin plates, meeting the high-density interconnection requirements of multi-layer PCBs and ensuring low-loss and low-delay connections between signal layers, providing physical support for the complex circuit architecture of quantum computing.

The power consumption of quantum computing chips and control circuits is considerable, and the heat dissipation challenge is huge in a low-temperature environment. On the one hand, the low-temperature cooling system and PCB heat dissipation need to cooperate to avoid local overheating affecting the coherence of qubits. On the other hand, conventional air-cooling heat dissipation is limited, and innovative heat dissipation structures are required. For example, heat sinks with high thermal conductivity coefficients can be attached to the surface of PCBs to quickly conduct heat out using metals such as copper and aluminum. The design of thermal via arrays can efficiently transfer heat from the inner circuit to the heat sink or the housing. Some high-performance quantum computing systems introduce liquid cooling technology. Micro-channel liquid cooling plates are integrated with PCBs, and the cooling liquid takes away heat. With the cooperation of the temperature control system to accurately adjust the temperature, the stable operation of the quantum computing system in a harsh thermal environment can be ensured, the coherence time of qubits can be extended, and the computing reliability can be improved.

In recent years, the market size of PCBs in the quantum computing field has shown a steady growth trend. According to the report of MarketsandMarkets, a market research institution, the global market size of PCBs related to quantum computing was approximately XX billion US dollars in 2023, achieving a growth rate of over XX% compared with 2018. This growth is mainly due to the continuous increase in scientific research investment in quantum computing, the gradual expansion of industrial applications, and the large-scale research and development layout of leading technology enterprises.

Looking to the future, with the exponential growth of the number of qubits and the acceleration of the commercialization process of quantum computers, it is expected that the global market size of quantum computing PCBs will break through XX billion US dollars by 2028, and the compound annual growth rate (CAGR) will reach XX%. Especially in core application scenarios such as high-performance computing chips, low-temperature control modules, and high-speed data transmission, the demand for high-end customized PCBs will become the key driving force for market growth, opening up a new blue ocean for PCB manufacturers.

Currently, the supplier pattern of the quantum computing PCB market presents a diversified situation. Europe and the United States, relying on their profound technological accumulation and advanced processes, dominate the high-end market. Amphenol RF, as a giant in the field of radio frequency interconnection, relying on its technological advantages in high-frequency and high-speed connectors and low-temperature adaptive interconnection products, has become one of the preferred suppliers for quantum computing hardware manufacturers, with a market share of over XX% in the fields of high-end quantum measurement and control board cards and quantum chip interconnection. AT&S, an Austrian company, relying on its advanced manufacturing processes for IC substrates and multi-layer boards, provides high-precision PCB solutions for quantum chip packaging and core control modules of quantum computing, and has a considerable share in the supply of European quantum computing projects.

Asia, relying on its complete electronic manufacturing industry chain, is rising rapidly. Japanese companies such as Ibiden and Shin-Etsu Chemical take advantage of their expertise in materials research and precision manufacturing to control key shares in the supply of high-end high-frequency materials and the manufacturing of quantum chip substrates. Companies in Taiwan, China, such as Unimicron Technology and Kinsus Technology, leverage their large-scale production advantages in packaging substrates and high-density interconnect (HDI) boards to actively enter the quantum computing supply chain. PCB enterprises in mainland China, such as Shennan Circuits and Huatian Technology, are emerging in the supply of PCBs for quantum computing infrastructure and supporting measurement and control equipment by virtue of their cost control and rapid response capabilities, gradually increasing the share of domestic substitution. They are expected to reshape the global competition pattern of quantum computing PCBs in the future and achieve dual breakthroughs in technology and scale.

Quantum error correction is a crucial step in realizing practical quantum computing. However, integrating its circuits on PCBs faces many difficulties. Quantum error correction codes usually require complex logic gate operations and a large number of auxiliary bits, which exponentially increase the complexity of PCB wiring. Taking the surface code as an example, the error correction process involves multi-bit entanglement gate and measurement feedback operations, requiring precise layout of dense control lines on the PCB, which is very likely to cause crosstalk between lines and destroy the delicate quantum states required for quantum error correction.

Signal synchronization is also a major challenge. Quantum error correction requires that all operations precisely cooperate within an extremely short time. A picosecond-level timing deviation may lead to the failure of error correction. In a multi-layer PCB structure, factors such as differences in signal transmission path lengths and via delays make it difficult to maintain high-precision synchronization. To solve this problem, it is necessary to take multiple measures. On the one hand, advanced high-speed multi-layer PCB design software should be adopted, and algorithms should be used to optimize wiring, automatically plan the shortest and equal-length paths, and reduce differences in transmission delays. On the other hand, a high-precision clock distribution network should be introduced, such as the clock distribution technology based on optical interconnection, to reduce the jitter of clock signal transmission and ensure that the clock synchronization accuracy of each quantum error correction module reaches the femtosecond level, laying a solid foundation for the stable operation of quantum error correction circuits.

As quantum computing expands to large-scale multi-qubit systems, the difficulty of PCB integration soars. In multi-qubit systems, the coupling between qubits is enhanced, and the crosstalk problem becomes more prominent. The manipulation signals of adjacent qubits may interfere with each other, causing the quantum states to be flipped incorrectly and deviating the calculation results from expectations. For example, in a superconducting qubit array, near-field electromagnetic coupling causes the microwave pulses for qubit manipulation to leak to adjacent qubits, destroying their quantum state coherence.

The power consumption problem cannot be ignored. The manipulation of a large number of qubits, frequent measurements, and data processing consume a large amount of electrical energy, and the heat dissipation pressure increases sharply. If the heat cannot be dissipated in time, the local temperature rise will accelerate the decoherence of qubits, shorten the coherence time, and reduce the computing fidelity. Layout optimization becomes the key to coping with this. By rationally partitioning the qubit manipulation area, measurement area, and data processing area on the PCB and using isolation grooves and ground shielding to reduce crosstalk, adopting low-power chip and circuit design technologies, such as dynamic power management and low-voltage swing signal transmission, to reduce power consumption from the source, and combining with efficient heat dissipation structures, such as micro-channel liquid cooling plates and thermal via arrays, to ensure that heat is evenly dissipated and maintain a low-temperature and stable operating environment for the quantum system, so as to break through the technical bottlenecks in the integration of large-scale quantum computing.

Currently, there is still a lack of unified and perfect industry standards and specifications for the design and manufacturing of PCBs in the field of quantum computing. Different quantum computing architectures and technical routes have different requirements for PCBs. From the types of qubits (superconducting, ion trap, optical quantum, etc.) to the operating environment (extremely low temperature, strong magnetic field, high vacuum, etc.), it is difficult to form a universal standard for PCBs. This leads to a sharp increase in the communication cost between quantum computing research and development teams and PCB manufacturers. They often need to repeatedly adjust the design details for specific projects, delaying the research and development cycle.