ITEQ IT-968G PCB for High-Speed Switch and Radar Designs

ITEQ IT-968G sits in the practical middle of the high-speed material decision: it offers very-low-loss electrical performance, high Tg, halogen-free construction, low CTE, and strong thermal/CAF reliability without automatically moving every project into the highest-cost ultra-low-loss tier. ITEQ’s current datasheet specifically positions it for 100G/400G switch solutions and publishes construction-dependent 10 GHz Dk and Df values.

The word “radar” in a project title needs careful qualification. IT-968G can be relevant to high-speed control, processing, base-station, automotive, and selected RF-support structures, but ITEQ’s dedicated 76–81 GHz radar laminate is IT-88GMW. A 77 GHz antenna layer should not be released as IT-968G merely because the material is low loss. The operating frequency, antenna efficiency, copper profile, dielectric tolerance, and temperature-stable design data must justify the choice.

This article therefore treats IT-968G as the “performance sufficient” option for switch and telecom channels, while defining where a dedicated radar or lower-loss material becomes necessary.

Why IT-968G Fits High-Speed Switch and Radar Boards

IT-968G is a high-Tg, halogen-free, ultra-low-loss laminate and prepreg system. The current ITEQ datasheet identifies a 100G/400G switch solution, stable Dk/Df under different environmental conditions, and advanced high-Tg resin technology. The product page also lists high-speed data-rate switch and base-station applications together with thermal and CAF reliability.

For switch cards, line cards, storage controllers, base-station digital sections, and moderate-reach backplanes, IT-968G can provide enough loss margin without the cost of IT-988GSE. The correct choice depends on route length, lane rate, copper roughness, connector count, via structure, and system equalization.

What “enough” means in a loss budget

A material is sufficient when the complete channel remains inside the insertion-loss, return-loss, crosstalk, skew, and jitter limits after production tolerance is included. That decision cannot be made from Df alone. A shorter IT-968G route with VLP copper and optimized vias may outperform a poorly designed route on a lower-Df material.

IT-968G is a strong candidate when:

• the route length is moderate rather than backplane-scale;
• connector and package loss are controlled;
• backdrill or blind-via design removes resonant stubs;
• the copper profile is specified;
• the channel model retains adequate manufacturing margin;
• cost or material availability does not justify IT-988GSE.

For the wider layout context, review high-speed routing constraints before choosing the laminate tier.

Radar use needs a boundary

IT-968G should not be presented as ITEQ’s primary 76–81 GHz radar antenna product. If a board includes a radar processor, digital interface, power section, or lower-frequency RF routing, IT-968G may be suitable in those layers or subassemblies. For the radiating antenna and mmWave feed network, compare it against IT-88GMW or another frequency-specific RF material using design Dk at the operating band, dielectric-thickness tolerance, copper roughness, and measured antenna efficiency.

A hybrid board may use IT-968G for high-layer digital sections and a dedicated RF laminate for the antenna section. Such a structure requires cure, CTE, resin-flow, dimensional-stability, and warpage qualification.

Material Snapshot

ITEQ’s current IT-968G datasheet provides two sets of Dk/Df values for 55% and 70% resin-content conditions. These values demonstrate why a single family number cannot be applied to every core and prepreg.

Why the RC55% and RC70% numbers matter

Woven glass has a higher dielectric constant than the resin system. A higher resin-content construction generally lowers the effective Dk and can change Df. The pressed dielectric thickness, glass weave, and resin fraction also affect impedance and skew. The stackup should identify the actual glass style and resin content rather than quoting only “IT-968G.”

Values are not finished-board guarantees

The datasheet values are typical material data. Finished impedance and loss depend on etch compensation, copper plating, foil roughness, inner-layer treatment, resin movement, trace geometry, and environmental condition. Use a controlled coupon plan to connect the laminate data to the manufactured board.

100G/400G Stackup and Impedance Planning

A useful stackup begins with the channel architecture. Assign critical pairs to layers with continuous reference planes, stable dielectric thickness, and low-profile copper. Keep the highest-rate channels away from thick copper planes or local copper imbalance that can disturb pressed thickness.

The material choice and layer geometry should be reviewed through 100G and 400G stackup planning before routing starts.

Design Dk by construction

The field solver should use the Dk for each core and prepreg construction. If the fabricator proposes a glass-style or resin-content change to improve availability, the impedance model must be recalculated. A change from RC55% to RC70% can materially change trace width, spacing, and phase delay.

The impedance table should include:

• single-ended and differential targets;
• tolerance and coupon method;
• layer and reference-plane assignment;
• finished trace width and spacing;
• finished copper thickness;
• dielectric thickness after pressing;
• design Dk used by the fabricator;
• solder-mask assumption for outer layers.

Route length, vias, and copper roughness

IT-968G reduces dielectric loss, but long routes remain sensitive to copper roughness. Specify RT or VLP foil where the loss budget requires it. Keep layer transitions to a minimum and model each signal via with its pad, antipad, residual stub, and return vias.

Backdrilling may be needed on thick boards. The drawing should define the target stub, depth tolerance, allowed breakout, and verification method. A backdrill callout without a measurable residual-stub requirement is incomplete.

Glass-weave and skew control

At high lane rates, differential-pair skew can arise when the two traces sample different proportions of glass and resin. Spread-glass options, angled routing, suitable trace width, and construction-aware placement can reduce this effect. The need should be based on pair length and timing margin rather than applied mechanically to every signal.

Fabrication and Hybrid-Stackup Controls

IT-968G is compatible with advanced multilayer processing, but the press cycle and dielectric constructions should follow ITEQ guidance and fabricator qualification. The stackup release must control core/prepreg identity, resin content, copper foil, target pressed thickness, and the acceptable equivalent rule.

Lamination and registration

High-layer-count switch boards require copper balance and predictable resin flow. Large copper-free areas may consume resin differently from dense routing regions. The fabricator should perform a resin-fill review, use appropriate thieving where allowed, and compensate for thickness variation without changing the electrical design silently.

Registration control is especially important when the board combines small antipads, backdrilled vias, and high aspect-ratio holes. Sequential lamination can reduce some via lengths but introduces additional registration and thermal histories.

Drilling, desmear, and plating

The resin system should be qualified with the selected desmear chemistry. Hole quality should be checked for smear removal, glass-fiber protrusion, resin recession, and copper adhesion. Plating thickness and uniformity should be matched to board thickness, hole diameter, and reliability class.

A robust first-article plan includes microsections through through holes, backdrills, and any hybrid interface. TDR coupons verify impedance; insertion-loss coupons are appropriate when the channel margin is close.

Hybrid radar/digital structures

When a dedicated RF laminate is used for the antenna and IT-968G is used for digital layers, the fabricator should verify:

• compatible cure temperatures and press sequence;
• CTE and modulus mismatch;
• bond-ply flow and RF keep-out control;
• dimensional movement between RF and digital artwork;
• panel flatness after lamination and reflow;
• drilling and plating through unlike materials;
• RF coupon and antenna test correlation.

Do not authorize a hybrid construction solely because both materials can survive the same peak temperature.

RFQ and FAQ

Provide protocol, lane rate, maximum route length, insertion-loss target, layer count, board size, finished thickness, exact IT-968G/IT-968GB construction, copper profile, target impedance, via and backdrill plan, radar operating frequency if applicable, antenna geometry, surface finish, reflow exposure, test coupons, and annual volume. Ask the fabricator to state the Dk used for every dielectric and any proposed substitute.

When is IT-968G enough instead of IT-988GSE?

It is enough when the full channel model, including copper and discontinuities, meets the loss and timing masks with manufacturing margin. Shorter or cleaner channels often do not need the lower Df of IT-988GSE.

Is IT-968G a dedicated 77 GHz radar antenna material?

No. ITEQ’s dedicated 76–81 GHz material is IT-88GMW. IT-968G may serve digital, control, base-station, or selected RF-support functions, but a 77 GHz antenna layer requires frequency-specific validation.

Why does the datasheet list two Dk/Df values?

They correspond to different resin contents. Effective dielectric properties change with the glass-to-resin ratio.

Can standard FR-4 impedance rules be reused?

No. Trace geometry must be recalculated with the selected construction’s design Dk, finished copper, and dielectric thickness.

What evidence should be requested from production?

At minimum, request stackup confirmation and TDR results. Add insertion-loss coupons, backdrill verification, and microsections when channel or reliability margin is tight.

Manufacturer references

• ITEQ IT-968G datasheet, revision 1.0-26
• ITEQ IT-968G product page