Maxipcb High-frequency and High-speed PCB Whole Process Testing Solution

introduction
In 2025, the global PCB market is welcoming a strong "bull market", with a total global output value of US$ 83 billion, among which the China market takes the lead with a share of nearly 57.2%.

However, with the transmission requirements of large model servers and 6G communication moving towards 112Gbps or even higher, "high frequency and high speed" has become a battleground for PCB industry. Along with it comes more stringent material Dk/Df control, more complex impedance matching, and more intractable signal integrity challenges. At this moment when opportunities and challenges coexist, how is a perfect high-frequency and high-speed PCB "refined"?

This article will dismantle the whole process test scheme from simulation, material verification, research and development to mass production test for your system.

1. What is a high-frequency and high-speed PCB?

1.1 technical definition and core parameters

Generally speaking, high-frequency PCB usually refers to the printed circuit board with working frequency ≥1GMHz, which is widely used in GHz or even millimeter wave frequency band. High-speed PCB refers to a digital circuit with signal rate ≥10Gbps, which is mainly used to transmit high-speed digital signals such as PCIe 5.0/6.0 and DDR5/6.

The core technical indicators of high-frequency and high-speed PCB are mainly manifested in two aspects: material characteristics and electrical performance:

In terms of material characteristics

Dielectric constant (Dk) and dielectric loss factor (Df) are the most critical parameters. The ideal high-frequency and high-speed PCB substrate requires a Dk value in the range of 2.0-4.5, and the batch-to-batch deviation should be ≤ 0.1, and the Dk fluctuation caused by temperature change (-40℃-125℃) should be ≤5%. The requirement of Df value is more strict, which is ≤ 0.005 (at 1 GHz) in high frequency scene and ≤0.002 in 28GHz millimeter wave scene.

In terms of electrical performance

Characteristic impedance is one of the core parameters of transmission lines. The common target impedance values are 50Ω, 75Ω (single-ended) and 100Ω (differential). The impedance control accuracy should be within 5% or even more stringent in high-frequency scenes. The importance of impedance matching is that the signal energy can be transmitted from the source to the load to the maximum, and the signal reflection and loss can be reduced.

1.2 classification of high-frequency and high-speed PCB

The classification system of high-frequency and high-speed PCB can be divided from many dimensions, including substrate type, application frequency, data transmission rate and so on.

According to the types of substrates, they are mainly divided into three categories: fluoride substrates (mainly PTFE), modified FR-4 substrates and ceramic composite substrates. In addition to these categories, there are also some PCB boards based on other special substrates.

From the perspective of application frequency, high-frequency and high-speed PCB can be mainly divided into: conventional high-frequency board (1-10GHz), ultra-high-frequency board (10-30GHz) and millimeter-wave board (> 30GHz).

From the perspective of signal transmission rate, high-frequency and high-speed PCB can also be divided into: high-speed board (10-25Gbps) and ultra-high-speed board (above 25Gbps).

Second, the development trend of high-frequency and high-speed PCB technology

The development of high-frequency and high-speed PCB technology shows an obvious upgrading trend, which is mainly reflected in three aspects: material technology, manufacturing technology and product structure.

01 in terms of material technology

The industry is evolving towards a higher performance material system. Specifically, the copper foil is upgraded to HVLP (ultra-low profile copper foil) series to meet the low signal loss requirements of AI servers; Resins are developing to low dielectric loss types, including hydrocarbon resins, polyphenylene ether (PPO) and polytetrafluoroethylene (PTFE), among which PTFE resin is expected to demand about 476 tons in AI servers in 2025. The low dielectric constant of glass fiber cloth and Shi Ying cloth are growing rapidly in response to the demand of high-speed communication; As a high-performance filler, the demand of silica micro-powder in China is 418,000 tons in 2024, and it is expected to reach 473,000 tons in 2025, with an increase of 13.2%.

02 in terms of manufacturing technology

PCB is evolving towards high density, high frequency and high speed. The technical indicators have been continuously improved: the line width accuracy has broken through to ≤20μm, the copper clad laminate has been upgraded from M6/M7 to M8/M9, and the technical barriers have been continuously improved. For example, a domestic head PCB manufacturer took the lead in introducing low-loss materials, and combined with blind buried hole technology, the signal transmission rate of PCB reached 112Gbps, which met the requirements of 800G and 1.6T optical modules.

03 in terms of product structure

The proportion of high-end products continues to increase. The total growth rate of four high-end categories, namely, high multilayer board, HDI, class carrier board and package substrate, is 18.8%, which is much higher than the industry average. According to the forecast of authoritative organizations, the new effective production capacity of global high-rise and multi-storey/HDI in 2026 will increase by 42% compared with that in 2023. This optimization of production capacity structure reflects the trend of high-end development of the industry.

Third, the test of high-frequency and high-speed PCB

3.1 Test content

Electrical characteristics testing of high-frequency and high-speed PCB is the key link to ensure product quality and performance, and its testing content system covers many dimensions from basic electrical parameters to complex signal integrity. According to industry standards and practical application requirements, the main test contents include signal integrity test and high frequency characteristic test.

Signal integrity testing is an important part of high-frequency and high-speed PCB testing, because it directly affects the performance of end products, and mainly includes the following items: Time domain reflection (TDR) testing, which is used to measure the impedance and impedance discontinuity of transmission lines; Time domain transmission (TDT) test, analyzing the attenuation and time delay of signals in the transmission line; Eye diagram test and jitter test, including random jitter and deterministic jitter.

In impedance testing, we need to pay special attention to the control accuracy of characteristic impedance. Typical requirements of characteristic impedance are 50Ω or 75Ω (single-ended) and 100Ω (differential), with tolerance of 5% and flatness of frequency response of 2%. For high-speed scenes (e.g., signals above 32GT/s), a vector network analyzer (VNA) with bandwidth ≥20GHz is preferred, and a differential probe (e.g., Keysight N1021B) can achieve 1% impedance accuracy.

High-frequency characteristic test focuses on RF performance evaluation, mainly including: S parameter test (10MHz-110GHz or even higher), such as S11 and S21, insertion loss and return loss are important performance indicators of PCB; The phase noise test is required to be ≤-100dBc/Hz at 10kHz frequency offset. These indicators directly reflect the performance of PCB in high frequency applications.

In addition to the above main test items, it also includes some auxiliary test contents: differential signal test, including parameters such as FEXT (far-end crosstalk), NEXT (near-end crosstalk), PS_Crosstalk (power and crosstalk), ICR (co-directional crosstalk suppression ratio) and ICN (co-directional crosstalk noise); Timing parameter testing, including Jitter, differential pair delay, etc. Material parameter testing, including dielectric constant (Dk)/ dielectric loss (Df), etc.

3.2 Challenges of testing

High-frequency and high-speed PCB testing faces many technical challenges, which come from many aspects such as material characteristics, testing accuracy, calibration and cost control.

The measurement and control of material properties is the primary challenge. High-frequency and high-speed PCB requires very strict dielectric constant (Dk) and dielectric loss (Df) of materials, which not only requires low values, but also requires stability when temperature and frequency change. However, the measurement of these parameters itself is very difficult. For example, the batch-to-batch deviation of Dk value should be controlled within ≤ 0.1, and the Dk fluctuation caused by temperature change (-40℃-125℃) should be ≤5%. At the same time, the differences in characteristics of different batches of materials and the changes in material characteristics during processing all increase the complexity of the test.

High frequency signal integrity testing is another important challenge. In the frequency band above 10GHz, the dielectric loss (Df) and conductor loss of materials lead to increased signal attenuation. The allowable error of impedance is more stringent, and it needs to meet the tolerance requirement of 5% or even more stringent; High density layout and electromagnetic coupling between differential signal pairs lead to serious crosstalk and affect signal accuracy. Especially in millimeter wave frequency band (above 28GHz), these problems are more prominent, which puts forward extremely high requirements for the performance of test equipment and the accuracy of test methods.

Calibration is a key challenge to ensure test accuracy. High-frequency testing is extremely sensitive to environmental factors, and temperature change, electromagnetic interference and mechanical vibration will all affect the test results. For example, the temperature stability requires 0.01 dB/C, which puts high demands on the constant temperature control of the test environment. At the same time, the calibration of test equipment is also facing challenges, especially in high frequency band, the accuracy of calibration parts and the selection of calibration methods directly affect the reliability of test results.

The efficiency of cost control and mass production test is particularly important in industrial production. The traditional manual testing method is inefficient and difficult to meet the needs of mass production. For example, the traditional test method may take 30 minutes/block, but the automatic test system can shorten it to 5 minutes/block. However, the establishment of automated test system requires a lot of upfront investment. How to find a balance between test accuracy, test efficiency and cost control is a realistic challenge for PCB manufacturers.

In order to meet these challenges, the industry is developing a variety of innovative solutions: using three-dimensional electromagnetic simulation and test data comparison technology, improving simulation accuracy and reducing physical test times through model calibration; Machine learning algorithm is introduced to predict PCB performance based on historical test data; For millimeter-wave PCB, the near-field scanning technology is used to visualize the electromagnetic field distribution and accurately locate the abnormal impedance points.

Fourth, the high-frequency and high-speed PCB solution of Maxipcb

4.1 High-frequency and high-speed PCB material testing

The performance of high-frequency and high-speed PCB and products ultimately depends on the materials, resin, glass fiber, copper foil and other accessories used in PCB itself. Accurate values of these material parameters are very important to ensure the performance of high-frequency and high-speed PCB. Keysight's network analyzer, with special test fixture and software, can accurately measure the dielectric constant (Dk) and dielectric loss (Df) of PCB materials in a wide frequency range (110GHz or even higher).

Keysight and its partners jointly provide a 110G high-frequency material testing system.

4.2 simulation of high-frequency and high-speed PCB characteristics

•ZA0129AS PCB simulation software is designed for impedance and loss control in high-speed channel transmission above 10Gbps, which can accurately predict PCB impedance and insertion loss characteristics even in the design of dozens of layers of high stack. It includes a comprehensive material database, a stack design tool and an impedance/insertion loss calculator, all of which are integrated into a unified system. Using this software, the accurate calculation of impedance and loss can be done in a few minutes, which avoids time-consuming prototyping and comparison, reduces the number of repeated trial and error, and helps enterprises choose suitable materials to reduce costs. At present, it has been used by many PCB manufacturers as a simulation tool for PCB characteristics before mass production.


Accurate and efficient ZA0129AS software interface for impedance and loss simulation of high-frequency and high-speed PCB, supporting material libraries of multiple manufacturers.

Advanced Design System (ADS)

Besides ZA0129AS, Maxipcb also provides an ADS high-speed circuit simulation design platform, which provides a complete signal and power integrity simulation solution. The unique advantage of ADS software lies in its collaborative simulation ability. Through the collaborative simulation of PCB and a single component, the complete inter-chip links, including channels, circuits or physical layers, can be analyzed. This method can find potential problems in the early stage of design and avoid repeated modifications in the later stage. It is an essential tool for product development and design engineers.

4.3 High-frequency and high-speed PCB performance development and verification test

As mentioned earlier, the characteristic impedance and loss, signal integrity (SI) and power integrity (PI) of high-frequency and high-speed PCB are all important items to be tested in the research and development process. Maxipcb provides a series of high-performance network analyzers, which are specially optimized for high-frequency and high-speed PCB testing requirements. Maxipcb's network analyzer can load TDR option, which has powerful time domain analysis function, convert frequency domain measurement data into time domain waveform, and realize accurate location of impedance discontinuity. This time-frequency domain joint analysis capability has become the industry standard for diagnosing the signal integrity of high-speed PCB.

In addition to testing the passive characteristics of PCB with mesh products, an oscilloscope will be used to verify the active state of PCB during the research and development process. Maxipcb's V series, Z series, UXR high-end oscilloscopes and various probes are powerful tools for testing the performance of various high-frequency and high-speed PCBs and products.

4.4 Test Scheme of High Frequency and High Speed PCB Production Line

On the production line, various manufacturers will adopt different testing methods and strategies according to their own product yield. If the product yield is high, sampling tests may be taken. The product yield is low, so the strategy of full testing may be adopted. No matter what kind of test strategy, automatic testing that can improve test efficiency has become a trend. Maxipcb provides matching test schemes according to different strategies of manufacturers.

Manual testing of single-layer PCB based on N5227A Automatic testing of multi-layer PCB based on N5227A and switch matrix

summarize

The global PCB market, especially the China market, has shown a strong growth trend. As a technical development direction, high-frequency and high-speed PCB has evolved to higher-performance materials, more precise manufacturing processes and higher-end product structures. At the same time, it also faces many challenges, including material property control, impedance and insertion loss testing, high-frequency signal integrity testing, multi-parameter comprehensive analysis and cost control.

Maxipcb provides a complete simulation and test scheme for high-frequency and high-speed materials and PCB, which represents the leading level in the industry in terms of frequency range, measurement accuracy, test speed and intelligence, and provides a strong backing for the R&D and production of high-frequency and high-speed PCB manufacturers.

About Maxipcb

Maxipcb inspires and empowers innovators and helps them bring world-changing technologies to life. We provide advanced design, simulation and testing solutions to help engineers complete development and deployment faster in the whole product life cycle, while controlling risks. Our customers are all over the world, such as communication, industrial automation, aerospace and national defense, automobile, semiconductor and general electronics. We join hands with customers to accelerate innovation and create a safe and interconnected world.