How Will 1.6T Networking Change Your PCB Material Needs?

The transition from 400G → 800G → 1.6T networking is not a linear upgrade.

It is a fundamental shift in signal physics, loss budget, and material dependency.

At 1.6T, systems typically rely on:

• 112G PAM4 (current generation)
• moving toward 224G PAM4 signaling
• extremely high channel density
• ultra-tight insertion loss budgets

At these data rates, traditional assumptions no longer hold:

• routing alone cannot fix loss
• impedance control alone is insufficient
• layout optimization cannot compensate for material limitations

Instead, the dominant factor becomes: the dielectric and conductor system itself

This means PCB material selection is no longer a secondary decision.

It becomes: a primary determinant of whether the system works at all

So the real engineering question is: How does 1.6T networking fundamentally redefine what "acceptable PCB material" means?

1. 1.6T Networking Is a Material-Limited Problem, Not Just a Design Challenge

At lower data rates, engineers could rely on:

• routing optimization
• via design
• equalization

to compensate for material limitations.

At 1.6T: this approach breaks down

Because:

• insertion loss increases rapidly with frequency
• signal margins shrink dramatically
• equalization has limits

The result: material loss becomes the dominant constraint

This shifts the problem from:

• layout-driven optimization

to: material-driven system performance

2. Why Loss Budget Becomes the Dominant Constraint at 224G PAM4

At 224G PAM4:

• Nyquist frequency increases significantly
• channel attenuation rises sharply

The system must operate within a strict: loss budget

If the PCB contributes excessive loss:

• signal amplitude collapses
• eye diagram closes
• BER increases

Unlike previous generations: you cannot "design around" excessive loss

You must: select materials that inherently meet the loss requirement

3. Dielectric Properties: Dk Stability and Df Are No Longer Optional

Two key parameters dominate:

Dk (Dielectric Constant)

• affects impedance
• affects signal velocity

At 1.6T:

• Dk variation causes timing skew
• inconsistent propagation delay affects synchronization

Df (Dissipation Factor)

• directly determines dielectric loss

Even small differences in Df: significantly impact insertion loss at high frequency

Material requirements now include:

• ultra-low Df
• stable Dk across frequency and temperature

4. Copper Surface and Roughness: The Hidden Loss Driver

At high frequency: current flows on the conductor surface

This makes copper roughness critical.

Traditional PCB materials use: roughened copper for adhesion

But roughness:

• increases effective path length
• increases resistance
• increases loss

At 1.6T: copper roughness can dominate total loss

This drives:

• smoother copper technologies
• mSAP-based processes
• advanced foil treatments

5. Glass Weave, Anisotropy, and Signal Skew at Ultra-High Speed

Traditional laminates contain: woven glass fiber

This creates:

• dielectric variation across the board
• anisotropic behavior

Effects include:

• differential pair skew
• impedance inconsistency
• signal distortion

At lower speeds:

• manageable

At 1.6T: unacceptable

Solutions include:

• spread glass
• low-weave-effect materials
• alternative substrate technologies

6. Thermal and Mechanical Stability Under Extreme Data Density

1.6T systems:

• generate high power density
• operate continuously

Material must support:

• stable dielectric properties under temperature
• minimal expansion mismatch
• reduced warpage

If not:

• impedance shifts
• mechanical stress increases
• reliability degrades

7. Stack-Up Evolution: Material + Geometry Co-Optimization

At 1.6T: material selection cannot be separated from stack-up design

Engineers must co-optimize:

• dielectric thickness
• copper geometry
• layer arrangement

This ensures:

• controlled impedance
• minimal loss
• stable power delivery

8. Manufacturing Reality: Material Variability vs Performance

Even high-performance materials have:

• batch variation
• process sensitivity

At 1.6T: tolerance windows are extremely narrow

Small variation leads to:

• performance drift
• yield issues

This requires:

• tight material control
• process consistency
• supplier capability alignment

In advanced PCB Assembly, HDI PCB, and High-Speed PCB, ULTRONIU addresses this by aligning material selection, stack-up engineering, and manufacturing process control—ensuring that high-speed performance targets are maintained not only in simulation but in volume production environments.

9. What a "1.6T-Ready PCB Material System" Actually Requires

A suitable material system must provide:

Electrical Performance

• ultra-low Df
• stable Dk

Conductor Optimization

• low roughness copper
• compatible with mSAP

Mechanical Stability

• low CTE mismatch
• minimal warpage

Thermal Stability

• consistent behavior across temperature

Manufacturing Compatibility

• repeatable processing
• scalable production

10. Strategic Conclusion: Material Engineering Becomes System Engineering

At 1.6T:

• materials define performance
• design refines performance

This reverses the traditional hierarchy.

The key shift: PCB material selection becomes system-level engineering

Technical Summary（Engineering Conclusions）

• 1.6T networking is limited by material performance
• Loss budget becomes the dominant constraint
• Dk and Df stability are critical
• Copper roughness significantly impacts loss
• Glass weave effects become unacceptable
• Thermal and mechanical stability matter
• Stack-up and material must be co-designed
• Manufacturing variation must be tightly controlled

At 1.6T, your PCB is no longer just a platform—it is part of the signal channel itself.