DiClad 527 PCB: Properties, Design & Fabrication

What Is a DiClad 527 PCB?

A DiClad 527 PCB is built on Rogers’ woven-fiberglass-reinforced PTFE laminate, which offers a dielectric constant (Dk) of 2.50 ± 0.04 at 10 GHz and a dissipation factor (Df) of approximately 0.0018. The combination of low loss and mechanical rigidity from E-glass reinforcement makes DiClad 527 a practical substrate for microstrip antennas, feed networks, and filters operating from UHF through Ka-band. Because the glass fabric is woven rather than random or non-woven, a DiClad 527 PCB holds tighter dimensional tolerances during drilling, routing, and thermal cycling than boards made from non-reinforced PTFE alternatives.

Key Electrical and Mechanical Properties

The table below summarizes the published properties that matter most during stackup design, impedance control, and reliability analysis for any DiClad 527 PCB. Values are from the Rogers DiClad data sheet unless noted otherwise.

The woven-glass construction gives DiClad 527 an x/y CTE significantly lower than non-reinforced PTFE (which can exceed 70 ppm/°C in-plane). This matters for plated-through-hole reliability and for hybrid multilayer builds where PTFE layers are bonded to FR-4 cores—mismatched CTE is the leading cause of barrel cracks in such stackups.

Where a DiClad 527 PCB Fits: Applications and Frequency Range

DiClad 527’s Dk of 2.50 sits between the ultra-low values of non-reinforced PTFE (Dk ≈ 2.17 for IsoClad 917) and the higher-Dk hydrocarbon ceramics (Dk 3.0–3.6). That middle ground makes it useful in several design scenarios:

• Patch antenna substrates — the moderate Dk yields wider bandwidth than Dk 3.0+ laminates for a given thickness, while keeping patch dimensions smaller than Dk 2.17 alternatives.
• Microstrip feed networks — 50 Ω trace widths on 20 mil (0.51 mm) DiClad 527 PCB material are about 1.36 mm, wide enough for standard etching tolerances yet narrow enough for compact layouts.
• Satellite and GPS receive modules — L-band through Ku-band circuitry benefits from the low loss and tight Dk tolerance.
• Automotive radar sub-assemblies — 24 GHz and 77 GHz front-end boards where the RF section is a single-layer microstrip bonded to a multilayer digital carrier.

For higher-frequency millimeter-wave work above 40 GHz, designers often move to materials with even tighter Dk control and smoother copper, such as Rogers RO3003G2 (Dk 3.00, Df 0.0010). DiClad 527 remains competitive at these frequencies when the design can tolerate its glass-weave effects.

Dk Drift with Temperature and Frequency on DiClad 527 PCB Designs

Every PTFE laminate shifts Dk as temperature changes. DiClad 527’s thermal coefficient of Dk is approximately +125 ppm/°C, meaning a 100 °C swing from room temperature to a hot automotive environment shifts Dk by about +0.031 (from 2.50 to roughly 2.53). That drift directly changes characteristic impedance and electrical length. Use the estimator below to see how much Dk moves for your operating temperature range.

For example, entering a baseline Dk of 2.50 and a temperature rise of 80 °C at 125 ppm/°C yields a shifted Dk near 2.525. On a 20 mil microstrip, that roughly 1 % Dk increase narrows the 50 Ω trace width by about 0.5 % and shifts filter center frequencies downward by approximately 0.5 %. In narrow-band filter designs, compensate by centering the layout at the expected median operating temperature rather than at 25 °C.

Glass-Weave Artifacts

Because DiClad 527 uses woven E-glass, the local Dk varies between resin-rich pockets (lower Dk) and glass-rich knuckles (higher Dk). At frequencies above roughly 20 GHz, this periodicity can create small resonant dips in insertion loss. Rotating the trace at 5–11° relative to the warp direction is a well-documented mitigation technique described in Rogers’ own laminate application notes. For glass-reinforced PTFE boards in general, specifying a tighter glass style (e.g., 1080 rather than 2116) also reduces the effect.

DiClad 527 PCB vs. Other Dk 2.50 Laminates

Several competing materials target the same Dk neighborhood. The comparison below helps you decide when a DiClad 527 PCB is the right pick and when an alternative serves better.

Choose a DiClad 527 PCB when you need Dk 2.50 with good dimensional stability and your frequency stays below 30–40 GHz. Choose TLX-9 when you want a second-source Dk 2.50 PTFE laminate with nearly identical specs. Choose RT/duroid 5870 when absolute minimum insertion loss matters more than mechanical rigidity—its random-fiber construction is softer and less stable dimensionally, but Df is about 33 % lower.

For designs that need even higher Dk for miniaturization, the DiClad 870/880 family offers Dk 2.33 with a different glass-to-PTFE ratio, while hydrocarbon ceramic laminates push Dk to 3.0 and above with better machinability than PTFE.

Fabrication and Processing Notes for DiClad 527 PCB

Drilling

PTFE is inherently soft and smears easily. DiClad 527’s woven-glass reinforcement reduces smear compared to non-reinforced PTFE, but carbide drills with a high helix angle (30–35°) and controlled chip loads (0.05–0.08 mm/rev) remain essential. Drill hit counts should stay below 2,000 per bit for holes under 0.5 mm diameter.

Copper Adhesion and Surface Preparation

PTFE’s low surface energy makes bonding challenging. Before solder-mask application or multilayer lamination, a sodium-naphthalenide etch (commonly called “sodium etch”) or plasma treatment activates the PTFE surface. DiClad 527’s published peel strength of ≥ 6 lb/in is adequate for most single- and double-sided builds, but multilayer hybrid stackups bonding PTFE to FR-4 prepreg should specify a bondply such as Rogers 3001 or Taconic FR-27 to bridge the material interface.

Plated-Through-Hole Reliability

The z-axis CTE of 173 ppm/°C is high—comparable to other woven-glass PTFE materials but far above FR-4’s 40–70 ppm/°C. For boards thicker than 62 mil (1.57 mm), specify at least 1.0 mil copper plating in through-holes and run IPC-TM-650 thermal-stress testing (288 °C solder float, 10 s) on qualification coupons. Blind and buried vias are uncommon in DiClad 527 builds; when required, sequential lamination with FR-4 bondplies and careful CTE matching is mandatory.

Cost Considerations

A DiClad 527 PCB sits in the mid-range of PTFE laminate pricing. It is less expensive than RT/duroid 5870 and 5880 because woven-glass reinforcement is cheaper to manufacture than random microfiber processes. However, it costs more than standard FR-4 by a factor of roughly 5–10×, depending on thickness and volume. Key cost drivers include:

• Panel size — Rogers ships DiClad 527 in 12 × 18 in and 18 × 24 in panels; larger custom sizes carry a premium.
• Copper weight — 2 oz cladding adds cost over ½ oz, and low-profile copper (for tighter Dk control at mmWave) adds more.
• Volume — minimum order quantities for non-standard thicknesses can be 25–50 panels.

Use the laminate cost index below to compare DiClad 527’s relative material cost against other PTFE and ceramic-filled options in your stackup.

If the calculator shows DiClad 527 at a cost index near 6 (with FR-4 at 1.0), and your design can tolerate a slightly higher Df, consider Taconic TLX-9 as a second source—its pricing tends to be competitive and its specs are nearly interchangeable, giving you leverage during procurement.

Design Guidelines for DiClad 527 Microstrip

1. Set Dk correctly in your field solver. Use 2.50 for preliminary layout and verify with the process Dk value from your fabricator’s incoming-material test. A ±0.04 tolerance means your 50 Ω line width can shift by ±1.5 %.
2. Account for copper roughness. Standard ED copper on DiClad 527 has an Rz of about 6–10 µm. At 10 GHz this adds roughly 0.003–0.005 dB/cm of extra conductor loss beyond the smooth-copper model. Use the Hammerstad-Jensen or Huray roughness correction in your simulator.
3. Minimize solder-mask on RF traces. Solder mask adds an unpredictable dielectric overlay. Leave RF signal traces and coupled-line sections exposed, covering only the ground areas and digital I/O.
4. Specify immersion silver or ENIG finish. HASL leaves uneven solder deposits that degrade impedance control on fine-pitch RF lines.
5. Control etch factor. Request etch compensation from your fabricator so that the finished trace width matches the target. On 1 oz copper, typical etch undercut is 0.5–1.0 mil per side.

Storage and Shelf Life

PTFE laminates are chemically inert and do not absorb significant moisture, so DiClad 527 PCB material has effectively unlimited shelf life when stored in sealed packaging at room temperature. Once opened, panels should be processed within 6 months to avoid surface oxidation on the copper cladding. If copper has tarnished, a light mechanical scrub (Scotch-Brite or micro-etch) restores solderability without damaging the PTFE surface.

Frequently Asked Questions

Is DiClad 527 the same as DiClad 880?

No. DiClad 527 has a Dk of 2.50, while DiClad 880 has a Dk of 2.17. Both are woven-glass PTFE, but the glass-to-resin ratio differs, giving each a distinct dielectric constant and different trace dimensions for the same impedance.

Can I use a DiClad 527 PCB in a multilayer stackup with FR-4?

Yes, hybrid PTFE/FR-4 multilayers are common. Bond the DiClad 527 RF layer to FR-4 cores using a thermoplastic bondply (e.g., Rogers 3001 or Rogers CuClad bondfilm). Careful CTE management and sequential lamination are required to avoid delamination.

What is the maximum operating frequency for a DiClad 527 PCB?

DiClad 527 performs well through Ka-band (26.5–40 GHz). Above 40 GHz, glass-weave effects become more pronounced, and designers typically move to laminates with finer glass styles or non-woven reinforcement.

Does DiClad 527 meet UL 94 flammability?

PTFE is inherently flame-retardant. DiClad 527 is rated UL 94 V-0 without the addition of halogenated flame retardants, which also benefits its loss tangent—halogen additives in FR-4 increase Df.

How does moisture absorption affect DiClad 527 PCB performance?

At 0.10 % moisture absorption, the impact is negligible under normal conditions. Water has a Dk near 78, so even small uptake in other materials can shift Dk noticeably. DiClad 527’s low absorption is one reason PTFE laminates are preferred for outdoor and marine antenna applications.