EU to Scrap €150 Tax-Free Threshold for Imports from July 1
2026-06-30
SHENZHEN, June 30, 2026 — The European Commission has officially notified that, effective July 1, 2026, the EU will abolish its long-standing €150 import duty exemption threshold. All parcels entering the EU, regardless of their value, will now be subject to customs duties, marking the end of the cross-border small-package tax-free era.
New Tariff Rules Take Effect
Under the new regulations, B2C (business-to-consumer) parcels valued at €150 or less will no longer enjoy duty-free treatment starting July 1. Customs duties will be calculated based on the number of tariff lines, at a rate of €3 per tariff line. For B2B (business-to-business) commercial parcels, duties will be calculated according to the applicable tariff rates based on the product's customs classification.
Stricter Customs Clearance Requirements
The new rules also impose stricter requirements on customs documentation. B2B commercial shipments must provide a valid VAT number and EORI (Economic Operators Registration and Identification) number. B2C private parcels must provide a valid IOSS (Import One-Stop Shop) number prior to shipment.
Logistics industry sources have cautioned that while shipments without an IOSS or VAT number may still be dispatched, they face a high probability of customs clearance delays, detention, or even return or destruction upon entry. Any resulting losses will be borne by the sender.
Invoice and Product Identification Rules
The invoicing standards have also been clarified: shippers must clearly indicate the trade nature as either "B2B" or "B2C" on the invoice. Additionally, starting November 1, 2026, B2C parcels will be subject to mandatory Product Identification (PID) requirements. Senders must provide the product's merchant information and manufacturer identification code, as well as the standardized product identification code if available.
View More
Bicheng 2026–2027 Holiday Schedule
2026-06-29
Dear Valued Customers and Business Partners,
To facilitate smooth communication, production planning, and order scheduling, we are pleased to provide our official holiday schedule for the remainder of 2026 and the upcoming 2027 Spring Festival. Please kindly adjust your order timelines and shipping arrangements accordingly.
Mid-Autumn Festival – September 25 to September 27, 2026 (3 days).
National Day – October 1 to October 7, 2026 (7 days).
Spring Festival (Chinese New Year) – February 2 to February 13, 2027 (12 days).
Please note that all production and shipping operations will be suspended during the holidays. Our sales team will remain available via email for urgent inquiries, but response times may be delayed.
Should you have any questions or require assistance with order scheduling, please do not hesitate to contact our customer support team.
We greatly appreciate your continued trust and partnership. Wishing you and your families a prosperous and joyful holiday season!
Yours sincerely,
Bicheng
View More
Why RO4835 Is the Unsung Hero of Automotive Radar PCBs
2026-06-25
When it comes to high-frequency PCB design, the material choice often dictates success or failure. This 2-layer board, built on Rogers RO4835, strikes an impressive balance between RF performance and manufacturing practicality. Let's break down why this design works and why it matters for engineers working on automotive radar, microwave links, and power amplifiers.
The Material That Makes It Possible
RO4835 is essentially the more thermally stable cousin of Rogers' well-known RO4350B. The key differentiator is oxidation resistance. Traditional thermoset microwave materials can degrade when exposed to repeated thermal stress. RO4835 holds up significantly better, maintaining consistent dielectric properties through multiple soldering cycles.
The numbers speak for themselves. With a dielectric constant of 3.48 ± 0.05 and a dissipation factor of 0.0037 at 10 GHz, this material delivers the low-loss performance required for circuits operating well into the microwave spectrum. The tight Dk tolerance of ±0.05 is particularly valuable—it means controlled impedance lines stay predictable across production batches, eliminating the need for post-production tuning.
Thermally, RO4835 is a beast. The glass transition temperature exceeds 280°C. This isn't just a number on a datasheet. It translates to real-world reliability during lead-free soldering. No blistering. No delamination. Just consistent performance through the harsh temperature profiles of modern assembly processes. The material also carries a UL 94 V-0 flammability rating and meets IPC-4103 specifications, making it suitable for safety-critical applications.
The coefficient of thermal expansion deserves attention too. At 31 ppm/°C in the Z-axis, plated through-holes experience less stress during thermal cycling. This directly impacts long-term reliability, especially in automotive applications where temperature swings from -40°C to +125°C are routine. The low in-plane expansion (10 ppm/°C on X-axis, 12 ppm/°C on Y-axis) ensures dimensional stability throughout circuit processing, from lamination through reflow soldering. When materials expand and contract at different rates, via barrels can crack and inner-layer connections can fail. RO4835 minimizes this risk.
Another critical advantage is the LoPro reverse-treated copper foil available with RO4835. This proprietary foil treatment reduces conductor surface roughness, which in turn reduces insertion loss at high frequencies. At 10 GHz and above, skin effect concentrates current at the conductor surface. Rough copper increases the effective path length and adds resistive losses. LoPro foil minimizes this effect, preserving signal amplitude through transmission lines.
A Stack-Up That Keeps It Simple
This is a no-frills 2-layer design. The core is 0.508 mm of RO4835, sandwiched between 1 oz copper on both sides. Total board thickness comes in at 0.6 mm. The dimensions—45 mm by 83.69 mm with ±0.15 mm tolerance—fit neatly into compact RF modules where space is at a premium.
Minimum trace width is 5 mils with 6 mils spacing, which supports controlled impedance lines while staying within standard fabrication capabilities. For a 50-ohm microstrip line on RO4835 with a 0.508 mm dielectric thickness, the trace width would be approximately 0.95 mm. This is a comfortable geometry that balances impedance control with manufacturability. The design rules are achievable with standard etching processes, avoiding the yield penalties associated with ultra-fine features.
The minimum hole size of 0.2 mm accommodates standard via drill sizes and through-hole component leads. The design incorporates 9 plated through-hole vias, each with a minimum copper plating thickness of 20 µm. This plating thickness is verified through microsection analysis per IPC-TM-650 2.2.18, ensuring sufficient current-carrying capability and mechanical robustness. No blind vias and no buried vias are specified, which simplifies the fabrication sequence and reduces manufacturing cost. For a 2-layer board, there is simply no need for these advanced via structures.
The "No Solder Mask" Decision
This might raise eyebrows for engineers accustomed to conventional PCB practices, but the absence of solder mask on both outer layers is a deliberate choice for high-frequency performance.
Solder mask isn't electrically neutral. It introduces dielectric loss and has uncontrolled permittivity that can perturb characteristic impedance. The dissipation factor of typical solder mask materials ranges from 0.02 to 0.08—an order of magnitude higher than RO4835's 0.0037. This means even a thin layer of solder mask can add measurable insertion loss, particularly at frequencies above 5 GHz. For microwave circuits, this is unacceptable. Removing the mask eliminates this variable entirely, ensuring that the circuit's electrical performance is determined solely by the controlled dielectric of RO4835.
Additionally, solder mask thickness and dielectric constant can vary across the board and from batch to batch. This variability introduces inconsistency in impedance-controlled lines, complicating design validation and production testing. Without solder mask, there are no such variations. The designer achieves consistent, predictable performance across every board.
The trade-off is cosmetic—boards won't have that polished green finish—but the electrical benefits are clear. In RF engineering, function trumps appearance.
Surface Finish and Silkscreen
Immersion gold (ENIG) is specified over electroless nickel. Nickel thickness ranges from 3 to 6 µm with gold thickness of 0.05 to 0.10 µm, compliant with IPC-4552. ENIG provides excellent solderability, corrosion resistance, and a flat surface for component attachment. The planar nature of the finish is particularly important for surface-mount components, ensuring consistent solder joint formation. The finish is compatible with both soldering and wire bonding, giving assembly flexibility.
The gold layer protects the nickel from oxidation, ensuring a fresh, solderable surface even after extended storage. ENIG is widely used in the industry and is supported by all major assembly houses.
Black silkscreen appears on the top layer only for component identification and reference designator marking. Bottom layer has no legend, reducing unnecessary steps in fabrication. Silkscreen is strictly excluded from pad areas to prevent contamination. Solder paste will not wet properly over silkscreen ink, and even small ink residues can lead to voiding, head-in-pillow defects, or poor wetting. Excluding silkscreen from pads is a simple but important design discipline.
Built to IPC Class 2
This isn't aerospace-grade Class 3, and it's not meant to be. IPC Class 2 is appropriate for general-purpose electronic products requiring moderate reliability. Minor cosmetic imperfections are acceptable, but all functional requirements—continuity, insulation resistance, thermal performance—are strictly enforced.
Class 2 provides a practical middle ground. It ensures quality without imposing the extreme requirements of Class 3, which would add cost without necessarily improving performance for this application. The standard specifies hole wall quality, minimum annular ring, and cleanliness levels that are achievable with standard manufacturing processes while still guaranteeing reliable operation.
Every board undergoes 100% electrical testing before shipping. Flying-probe or fixture-based systems verify continuity of all nets, isolation between non-connected nets, and detection of opens or shorts. No defective units leave the factory. This comprehensive screening ensures that every board functions as designed, supporting worldwide distribution without requiring additional inspection at the customer site.
Where This PCB Shines
Automotive radar is the obvious use case—24 GHz and 77 GHz systems where low loss and thermal stability are non-negotiable. The material handles the harsh under-hood environment, while the straightforward design keeps costs manageable. Radar sensors are increasingly common in modern vehicles for adaptive cruise control, collision avoidance, and blind-spot detection. These systems must operate reliably in extreme temperatures, vibration, and humidity. RO4835 delivers that reliability.
Beyond automotive, this PCB is suitable for point-to-point microwave links, power amplifiers, phased-array radar, and general RF components like filters and couplers. The material's low loss and tight Dk tolerance enable consistent performance in these demanding applications.
The Bottom Line
This 2-layer board demonstrates that high-frequency design doesn't always require exotic PTFE materials or complex multilayer stack-ups. RO4835 delivers the electrical performance needed for demanding microwave applications while remaining compatible with standard FR-4 fabrication processes. The result is a cost-effective solution for performance-sensitive, high-volume production. No unnecessary complexity. No over-engineering. Just good design decisions backed by solid material science.
For engineers working on automotive radar or similar RF applications, this design offers a proven reference point—one that balances performance, reliability, and manufacturability in equal measure. And in the competitive world of automotive electronics, that balance is what separates successful products from also-rans.
View More
6-Layer Hybrid PCB: Blending RO4003C RF Performance with FR-4 Processability
2026-06-22
What do you do when your RF design demands high-frequency performance, but your budget cannot accommodate the specialized processing of PTFE materials? You build a hybrid PCB. You combine a high-performance RF laminate for the critical signal layers with a standard FR-4 core for the rest. You get the best of both worlds: premium electrical characteristics and affordable fabrication.
Today I am looking at a 6-layer hybrid rigid PCB that does exactly that. It pairs RO4003C hydrocarbon ceramic material with Tg170°C FR-4, delivering controlled impedance, blind vias, and IPC-Class-3 reliability in a single board.
Let me walk you through the construction.
Construction Overview: A 6-Layer Hybrid Construction
This is a 6-layer rigid PCB measuring 127mm by 103mm, including the process edge. The finished lamination thickness is 1.74mm, with 1oz of finished copper on every conductive layer.
The stackup is what makes this board interesting. It combines two material families:
RO4003C core – a glass-reinforced hydrocarbon ceramic thermoset laminate for high-frequency layers
Tg170°C FR-4 prepreg and core – standard FR-4 material for the remaining layers
This hybrid approach allows the designer to place the critical RF signal paths on the RO4003C layers while using lower-cost FR-4 for power distribution, ground planes, and less sensitive signals.
The surface finish is hard electrolytic gold plating – a robust choice for boards requiring good wear resistance and long shelf life. Both sides have green solder mask with white silkscreen legend.
The board includes blind vias connecting L1-L2 and L5-L6, with a hole copper thickness of 25μm. Full controlled impedance circuitry is implemented across the board. Quality standard is IPC-Class-3, the highest reliability class for high-performance electronic equipment.
RO4003C: The RF Core of the Hybrid
Let me focus on the star material – RO4003C – because this is what makes the board's high-frequency performance possible.
RO4003C is Rogers' glass-reinforced hydrocarbon ceramic thermoset laminate. It is designed specifically for high-frequency circuits operating above 500MHz, where standard FR-4 can no longer meet RF electrical requirements.
Why choose RO4003C over PTFE-based laminates?
The answer is simple: processability. Unlike PTFE materials, RO4003C requires no specialized sodium etching via pretreatment. It is fully compatible with standard FR-4 manufacturing processes – drilling, desmear, copper plating, and etching can all be done using conventional equipment. This dramatically reduces fabrication cost and lead time, while still delivering premium RF performance.
Electrical performance is solid. The material maintains a stable dielectric constant across a wide frequency range, with an ultra-low temperature coefficient of dielectric constant (TCDK). This means your impedance-controlled transmission lines will stay consistent across temperature variations – critical for broadband RF and microwave circuits.
Thermal properties are equally impressive. With a glass transition temperature (Tg) exceeding 280°C, RO4003C maintains stable thermal properties throughout the entire PCB fabrication thermal cycle – including multiple lamination steps for the hybrid stackup. The CTE value matches copper foil closely, ensuring excellent dimensional stability. The low Z-axis CTE secures plated through-hole integrity even under severe thermal shock conditions.
Optional LoPro® copper foil is available to further minimize insertion loss for broadband applications. For this design, standard copper foil is used, but the option exists for even more demanding applications.
Understanding the Hybrid Approach
Why go hybrid rather than using RO4003C for all six layers? The answer is cost optimization.
RO4003C is more expensive than FR-4. By using it only where it is needed – typically the outer signal layers or critical RF routing layers – and using FR-4 for inner layers that carry power, ground, or lower-speed signals, you get the RF performance you need without paying for premium material where it is not necessary.
The Tg170°C FR-4 used in this design is itself a high-performance FR-4 variant. Standard FR-4 has a Tg of around 130-140°C. Tg170°C FR-4 offers better thermal stability, making it compatible with the RO4003C lamination process and ensuring the hybrid board can withstand multiple thermal cycles during fabrication and assembly.
Process Features: Blind Vias
The board includes blind vias connecting L1-L2 and L5-L6. These are not through vias that penetrate the entire stackup – they stop at the second and fifth layers respectively.
Why use blind vias? Three reasons:
Increased routing density – blind vias free up routing space on the inner layers
Reduced via stub effects – shorter via stubs mean better signal integrity at high frequencies
Improved power distribution – blind vias can connect surface components directly to inner power or ground layers without crossing the entire board
The 25μm hole copper thickness is standard for IPC-Class-3 requirements, ensuring robust mechanical and electrical connections.
Controlled Impedance: A Requirement, Not an Option
Full controlled impedance circuitry is specified for this board. At RF and microwave frequencies, impedance mismatch causes signal reflections, power loss, and degraded performance. Controlled impedance ensures that the characteristic impedance of each transmission line matches the source and load impedances – typically 50Ω for RF systems.
The combination of RO4003C's tight Dk tolerance and the hybrid stackup design allows the fabricator to achieve precise impedance control. The laminating process with RO4003C ensures consistent dielectric thickness and Dk across the critical signal layers.
Hard Electrolytic Gold: A Robust Surface Finish
Hard electrolytic gold plating is specified for this design. Unlike soft gold or ENIG (electroless nickel immersion gold), hard gold contains cobalt or nickel hardeners, making it more durable and wear-resistant.
This surface finish is ideal for:
Boards with high mating cycle requirements (such as edge connectors)
Applications requiring long shelf life
Environments where corrosion resistance is critical
The trade-off is that hard gold is more expensive than ENIG, but for high-reliability applications, the durability is well worth the cost.
Quality Standard: IPC-Class-3
This board is manufactured to IPC-Class-3, the highest reliability class defined by the IPC standards. Class-3 boards are required for:
Aerospace and military equipment
Medical devices
Automotive safety systems
High-reliability infrastructure equipment
Class-3 requirements include stricter tolerances on hole copper thickness (25μm vs. Class-2's 20μm), tighter inspection criteria, and more rigorous testing. The 100% electrical test and full impedance control specified for this board are consistent with Class-3 expectations.
Typical Applications
Based on the material combination and design features, this hybrid PCB is well-suited for:
Broadband RF and microwave communication circuits
Controlled impedance transmission lines and signal matching networks
Commercial radar, antenna, and wireless transceiver modules
Base station radio units and wireless communication infrastructure
Multi-layer mixed-dielectric high-frequency PCBs
High-frequency sensing and industrial RF devices
Design Considerations
If you are considering a similar hybrid design, here are a few points to keep in mind.
Material compatibility is critical. RO4003C and FR-4 have different CTE values. While RO4003C is designed to match copper closely, FR-4's CTE is slightly different. The lamination process must be carefully controlled to minimize stress between layers. The Tg170°C FR-4 used in this design helps by providing better thermal matching than standard FR-4.
Blind via registration requires precision. With six layers and two pairs of blind vias (L1-L2 and L5-L6), registration accuracy is essential. Misalignment can cause opens or shorts. Your fabricator must have experience with sequential lamination and blind via formation.
Controlled impedance tolerance depends on the prepreg thickness. In a hybrid stackup, the dielectric thickness between layers is determined by the prepreg thickness. Variations in prepreg thickness directly affect impedance. Work with your fabricator to define acceptable tolerance ranges early in the design phase.
Final Thoughts
This 6-layer hybrid PCB demonstrates a practical approach to high-frequency design: use a premium RF laminate where it matters, pair it with cost-effective FR-4 where it does not, and leverage FR-4 processability to keep fabrication costs under control.
RO4003C delivers the electrical performance – stable Dk, low loss, excellent thermal stability – without the processing headaches of PTFE. The blind vias add routing density and improve signal integrity. The IPC-Class-3 standard ensures the board can withstand the most demanding applications. And the hard gold finish provides long-term durability.
If your next RF design requires controlled impedance, multilayer integration, and cost-effective production, this hybrid approach is well worth considering.
Have you worked with hybrid stackups combining RO4003C and FR-4 before? What challenges did you encounter with material matching or blind via registration? Drop your experience in the comments.
View More
What Makes TFA294 an Aerospace-Grade Alternative to Foreign High-Frequency Laminates
2026-06-10
What happens when you remove the solder mask, remove the silkscreen, and even remove the glass fiber cloth from the substrate? You get a board that is built for one thing only: clean, predictable, high-frequency performance.
Today I am looking at a two-layer rigid PCB built on TFA294 – a PTFE-ceramic composite from the TFA series. This is not your standard RF laminate. It contains no glass fiber cloth, minimizes anisotropy, and delivers a dissipation factor of just 0.0010 at 10GHz. Let me walk you through the design.
PCB Overview: Simple Structure, Serious Intent
The board measures 97.53mm by 100.28mm. Finished thickness is 1.1mm, with 1oz of copper on both outer layers (approximately 35μm). The minimum trace width is 4 mils with 6 mil spacing, and the smallest drilled hole size is 0.35mm. There are no blind vias. Via plating thickness is 20μm, and every board undergoes 100% electrical testing before shipment.
The surface finish is Immersion Gold – a solid, reliable choice for RF work.
Like several designs I have covered recently, this board has no solder mask and no silkscreen on either side. That is becoming a familiar theme for high-performance RF boards: remove the variables, remove the uncertainty.
TFA294: A Different Kind of PTFE Laminate
Now let me focus on the material, because TFA294 is genuinely different from most PTFE-based laminates on the market.
The TFA series uses a dielectric layer composed of PTFE resin and ceramics. But here is the key difference: it contains no glass fiber cloth. Traditional PTFE laminates like RT/duroid are reinforced with woven fiberglass. That glass reinforcement does two things – it adds mechanical strength, but it also introduces microscopic inhomogeneities. When electromagnetic waves propagate through glass fibers, they scatter and distort. The effect is small, but at higher frequencies and in sensitive applications, it matters.
TFA eliminates the glass fiber entirely. Instead, it uses a new process to create prepreg sheets with uniformly dispersed nano-ceramics. The result is a material with minimal X/Y/Z anisotropy. The electrical properties are the same in every direction. No fiberglass weave effect. No unexpected variations.
Electrical Performance: Low Loss, Stable Dk
For TFA294, the numbers are impressive.
At 10GHz, the dielectric constant (Dk) is 2.94. At 20GHz, the dissipation factor (Df) is just 0.0010 – that is exceptionally low. Even at 40GHz, the Df remains low at 0.0012. This material will not eat your signal, even at millimeter-wave frequencies.
The temperature coefficient of dielectric constant (TCDK) is -5 ppm/°C across the range of -55°C to 150°C. That is outstanding. For comparison, many standard RF materials have TCDK values in the range of -20 to -50 ppm/°C. A TCDK of -5 ppm/°C means the dielectric constant barely moves with temperature. Your antenna will not drift significantly between a cold morning and a hot afternoon.
Thermal and Mechanical Properties
The thermal and mechanical numbers are equally solid.
Coefficients of thermal expansion are 18 ppm/°C on both the X and Y axes, and 32 ppm/°C on the Z axis. The X/Y values match copper very well – copper sits at approximately 17 ppm/°C. This close match reduces stress on plated through-holes and surface mount pads during thermal cycling.
Thermal conductivity is 0.59 W/m·K. That is roughly double that of standard FR-4, helping with power dissipation in amplifier or feed network applications.
Moisture absorption is just 0.03 percent – extremely low. PTFE materials are naturally hydrophobic, and the ceramic loading does not change that. This board will maintain stable performance even in humid environments.
Flammability rating is UL 94-V0, meeting standard safety requirements for most aerospace and defense applications.
Why No Glass Fiber Matters
I want to spend a moment on the glass-free construction because it is genuinely important.
Traditional PTFE/ceramic laminates use glass fiber cloth as a reinforcement. The glass fibers have a different dielectric constant than the PTFE-ceramic mixture. As an electromagnetic wave travels across the board, it encounters these fibers and scatters. The effect is called "fiber weave effect" or "glass weave effect." At lower frequencies, it is negligible. At microwave frequencies and above, it can cause phase variations across an array – a disaster for phased array antennas.
By removing the glass fiber entirely, TFA294 eliminates this problem. The dielectric constant is uniform across the entire board. Every patch antenna in a phased array sees the same electrical environment. Phase consistency improves. Beamforming becomes more precise.
The combination of ultra-low loss, stable Dk across temperature, matched CTE to copper, and glass-free construction makes this material suitable for applications where failure is not an option: space equipment, airborne radar, satellite communications, and navigation systems.
Typical Applications
Aerospace equipment, space systems, cabin electronics, and aircraft
Microwave circuits, antennas, and phase-sensitive antennas
Early warning radar and airborne radar systems
Phased array antennas and beamforming networks
Satellite communications and navigation equipment
Power amplifiers
A Few Practical Notes
Before you take this design into production, here are a few things to keep in mind.
First, like all PTFE-based materials, TFA294 requires special hole preparation. The PTFE surface is chemically inert. Standard FR-4 desmear processes will not work. Your fabricator must use plasma or sodium naphthalene treatment before copper plating. Confirm this capability upfront.
Second, the no-mask design means the copper is fully exposed. Immersion gold provides protection, but the board should be handled with care. Clean gloves, sealed storage, and careful assembly are essential.
Third, the material contains no glass fiber cloth. This is a benefit for electrical performance, but it does mean the board may be slightly less rigid than glass-reinforced alternatives at the same thickness. At 1.1mm thickness, this is unlikely to be an issue, but it is worth noting for very large panels or rough handling conditions.
Final Thoughts
This two-layer TFA294 board is a study in purposeful design. Remove the mask. Remove the silkscreen. Remove the glass fiber. Keep only what matters: low loss, stable Dk, matched CTE, and clean signal propagation.
Is TFA294 a direct replacement for established materials like Rogers RT/duroid? That depends on your specific requirements. But for aerospace, radar, and satellite applications where glass weave effect is a real concern and temperature stability is critical, this material deserves serious consideration.
Have you worked with glass-free PTFE-ceramic composites before? How did they compare to traditional woven-reinforced laminates in your application?
View More

