Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
Arlon IsoClad 933: The Engineer’s Complete Guide to This Isotropic PTFE Laminate for Microwave Circuits
If you’ve been specifying RF laminates for long enough, you’ve probably heard the name Arlon IsoClad 933 come up whenever a project demands a nonwoven PTFE substrate with a well-balanced mix of electrical performance and mechanical robustness. It sits in a particular sweet spot that not every material family can occupy — low enough loss to matter at microwave frequencies, dimensionally stable enough to survive real-world fabrication, and isotropic by design so your circuit behaves the same regardless of which direction signals travel across the board.
This guide cuts through the datasheet language and explains what IsoClad 933 actually does, why its construction choices matter, how it compares to competing materials, and where it genuinely makes sense to use it. Whether you’re designing a phased array feed network, a conformal antenna, or a power amplifier board, the goal here is to give you the working knowledge to make a confident material decision.
Arlon IsoClad 933 is a nonwoven fiberglass-reinforced PTFE (polytetrafluoroethylene) composite laminate developed by Arlon Electronic Materials, designed specifically as a printed circuit board substrate for RF and microwave circuit applications. The “933” designation reflects its nominal dielectric constant of Er = 2.33, and it belongs to the broader IsoClad product family — a line of nonwoven PTFE composites that prioritize isotropic electrical behavior.
The material is manufactured as a copper-clad laminate, available with standard electrodeposited (ED) copper cladding in various weights. It comes in master sheet sizes of 36″ × 48″ and 36″ × 72″, with standard thicknesses ranging from 0.005″ (0.127mm) all the way up to 0.062″ (1.575mm), covering the vast majority of microwave circuit builds.
What sets IsoClad 933 apart within the IsoClad family is its higher fiberglass-to-PTFE ratio compared to IsoClad 917. More glass in the matrix means better dimensional stability, increased mechanical strength, and tighter registration during fabrication — but trades a small amount of raw electrical performance in return. For many microwave applications, that’s exactly the right tradeoff.
After Arlon was acquired by Rogers Corporation, the IsoClad product line has continued to be manufactured and supported. When you’re searching for Arlon PCB materials today, the products are still widely referenced under the Arlon brand name and stocked by numerous specialty distributors globally.
Key Electrical and Physical Properties of Arlon IsoClad 933
Understanding the numbers behind the material is the starting point for any serious design evaluation. The table below summarizes the published typical properties of IsoClad 933.
Table 3: Arlon IsoClad 933 — Available Standard Thicknesses
Thickness (inches)
Thickness (mm)
Nominal Dk
0.005″
0.127
2.33
0.010″
0.254
2.33
0.015″
0.381
2.33
0.020″
0.508
2.33
0.031″
0.787
2.33
0.045″
1.143
2.33
0.060″
1.524
2.33
Note: All values listed are typical properties from published datasheets. They should not be treated as specification limits. Verify with your material supplier for lot-specific data.
A dissipation factor of 0.0016 at 10 GHz is genuinely low — not quite in the league of the most exotic glass microfiber PTFE composites like RT/duroid 5880 (Df ≈ 0.0009), but well within the range that puts it firmly in “real microwave substrate” territory. For the majority of commercial RF work in the 1–20 GHz range, this performance level is entirely sufficient and sometimes preferred because the higher fiberglass content gives you better mechanical control on the fab floor.
Why “Isotropic” Matters: The IsoClad Design Philosophy
The “Iso” in IsoClad isn’t just branding. It reflects a specific engineering decision: by using nonwoven fiberglass reinforcement rather than the conventional woven glass cloth used in materials like DiClad or standard FR-4, the fiber distribution becomes essentially random in the X-Y plane.
In a woven glass laminate, the fiberglass yarns run parallel in two directions — typically the warp and fill directions of the cloth. At the scale of microwave wavelengths, particularly as frequencies climb above 5 GHz, this anisotropy creates measurable differences in Dk depending on signal orientation relative to the cloth weave. The result is that transmission line impedances can shift subtly depending on how your layout is oriented with respect to the material grain — exactly the kind of silent performance problem that makes late-stage RF debugging painful.
IsoClad 933’s nonwoven construction eliminates this issue. The dielectric constant is uniform in all in-plane directions, which means:
Transmission line impedance calculations hold up regardless of trace orientation
Antenna patterns from arrays are not subtly skewed by material anisotropy
Batch-to-batch consistency in electrical behavior is easier to maintain
Arlon achieves this through longer random fibers and a proprietary manufacturing process that produces better Dk uniformity compared to competitive nonwoven PTFE products. The practical benefit shows up most clearly in tight-tolerance applications: filter designs, precision coupler networks, and antenna feed lines where even small Dk variations produce noticeable passband shifts.
The nonwoven construction also has a secondary benefit: it makes the laminate more suitable for applications where the finished circuit needs to be bent or formed into a non-planar shape. Conformal antennas — the kind that wrap around a fuselage or a cylindrical housing — are one of the classic use cases for this material family, and the flexible behavior of nonwoven fiber reinforcement is a key enabler for that.
IsoClad 933 vs. IsoClad 917: Choosing Within the Family
Before comparing IsoClad 933 against external competitors, it’s worth understanding the choice between it and its sibling, IsoClad 917.
Table 4: IsoClad 933 vs. IsoClad 917 — Side-by-Side Comparison
Parameter
IsoClad 917
IsoClad 933
Nominal Dk @ 10 GHz
2.17 / 2.20
2.33
Fiberglass/PTFE Ratio
Lower (more PTFE)
Higher (more glass)
Dissipation Factor
Lower
Slightly higher (0.0016)
Dimensional Stability
Good
Better
Mechanical Strength
Lower
Higher
Best For
Lowest loss priority
Stability + performance balance
IsoClad 917 uses a low fiberglass-to-PTFE ratio to push the Dk down toward 2.17 and minimize dielectric losses as much as possible. It’s the right choice when you’re after the absolute minimum insertion loss and dimensional stability is handled by careful fixturing in the fab process.
IsoClad 933 trades a bit of that raw electrical performance for a more highly reinforced substrate. The higher fiberglass content means better resistance to dimensional changes during etching and lamination, tighter hole registration in multi-layer builds, and a laminate that’s slightly more forgiving to process.
From a PCB engineer’s standpoint: if you’re doing single-layer or simple double-sided work where mechanical tolerances are less critical, IsoClad 917 might squeeze out that last 0.1 dB. If you’re building anything with tighter registration requirements — multi-layer stacks, fine-pitch features, or designs that go into volume production — IsoClad 933 is usually the safer choice.
How Arlon IsoClad 933 Compares to Other Microwave Laminates
It would be incomplete to evaluate IsoClad 933 without understanding where it sits relative to the wider landscape of PTFE-based microwave substrates.
Table 5: Arlon IsoClad 933 vs. Competing PTFE Laminates
Material
Manufacturer
Dk @ 10 GHz
Df @ 10 GHz
Reinforcement Type
Relative Cost
IsoClad 933
Arlon (Rogers)
2.33
0.0016
Nonwoven glass/PTFE
Moderate
IsoClad 917
Arlon (Rogers)
2.17
~0.0009–0.0013
Nonwoven glass/PTFE
Moderate
RT/duroid 5880
Rogers
2.20
0.0009
Glass microfiber/PTFE
High
CuClad 250GT
Arlon (Rogers)
2.40–2.60
0.0018
Woven glass/PTFE
Moderate
DiClad 880
Arlon (Rogers)
2.17–2.60
~0.0010–0.0018
Woven glass/PTFE
Moderate
CLTE
Arlon (Rogers)
2.98
Low
Ceramic/micro glass/PTFE
Moderate-High
RO4350B
Rogers
3.48
0.0037
Hydrocarbon ceramic
Moderate
A few important points emerge from this comparison:
Against RT/duroid 5880: Rogers’ glass microfiber PTFE composite is the gold standard for ultra-low loss, and its Df of 0.0009 beats IsoClad 933 comfortably. However, RT/duroid 5880 is more expensive, and for designs operating below Ka-band (around 26 GHz), the performance delta doesn’t always translate to meaningful system-level improvement. IsoClad 933 covers the X-band and below territory very well.
Against CuClad 250GT: CuClad uses cross-plied woven fiberglass, which gives excellent dimensional stability and slightly lower anisotropy than standard woven substrates, but still won’t match the true isotropy of IsoClad 933’s nonwoven construction. For designs where in-plane Dk uniformity matters — especially circular polarization work or complex antenna patterns — IsoClad 933 has a real advantage.
Against RO4350B: The hydrocarbon ceramic laminate from Rogers can be processed using standard FR-4 methods (no sodium etch required), which makes it popular in fab environments. Its Dk of 3.48 and Df of 0.0037 reflect its different material system. IsoClad 933 has lower loss and a much lower Dk, which translates directly to wider transmission lines and lower conductor loss at the same impedance — often a net win in terms of insertion loss.
Against CLTE: Arlon’s ceramic-filled PTFE family is designed for very low Z-axis CTE, making it the preferred material for applications with aggressive through-hole reliability requirements. IsoClad 933 is not optimized for thermal expansion management; CLTE is the right tool for harsh thermal cycling environments.
Primary Applications for Arlon IsoClad 933
Phased Array Radar Feed Networks
Phased array systems require precise phase relationships between antenna elements. Even tiny Dk variations across the feed network translate directly into phase errors that degrade beam pointing accuracy and increase sidelobe levels. The isotropic, uniform Dk of IsoClad 933 across the board area makes it well-suited for the corporate feed structures and beam-forming networks in these systems.
Base Station Antenna Substrates
Cellular infrastructure antennas — whether traditional sectors or the massive MIMO arrays driving 5G deployments — demand consistent electrical performance at production scale. IsoClad 933’s combination of reliable Dk, low dissipation factor, and good mechanical properties makes it a practical choice for commercial antenna board production.
Conformal and Wrap-Around Antenna Designs
This is one of the most distinctive application advantages of the IsoClad series. The nonwoven fiberglass reinforcement allows IsoClad 933 to flex more easily than woven glass laminates when a circuit needs to be formed around a curved surface. Wrap-around antennas on missiles, UAVs, vehicle bodies, or satellite structures regularly specify this material or its close relatives for exactly this reason.
Power Amplifier Boards
The low dielectric loss helps keep substrate-induced heat generation to a minimum in power-dense circuits. Combined with the stable Dk behavior across temperature, IsoClad 933 performs predictably in PA designs where bias networks and matching structures need to maintain their intended response even as the board heats up under full RF drive.
Combiner and Divider Networks
Wilkinson power dividers, rat-race couplers, and branch-line hybrids are highly sensitive to Dk accuracy. Small errors in Dk produce direct errors in electrical length for the quarter-wave sections that define these components’ performance. IsoClad 933’s flat Dk versus frequency response and excellent uniformity within a sheet make it a reliable substrate for these types of passive networks.
Microstrip and Stripline Transmission Lines
At frequencies from roughly 1 GHz to 20 GHz, IsoClad 933 supports clean microstrip and stripline designs with predictable impedance. The dielectric constant of 2.33 produces line widths that are wider than higher-Dk materials at the same impedance target — wider lines mean lower conductor resistance, which helps insertion loss, especially at lower GHz frequencies where conductor loss is the dominant term.
Fabrication Considerations for Arlon IsoClad 933
Working with PTFE-based laminates on the production floor requires some process adjustments compared to standard FR-4. If you’re designing for IsoClad 933, it’s worth communicating these requirements clearly to your fabrication partner.
Surface Preparation Before Plating
PTFE is chemically inert, which is part of why it has such excellent electrical properties — but that same inertness means that standard electroless copper adhesion is poor on bare PTFE surfaces. Before plating through-holes or vias, the PTFE surface requires either sodium naphthalene (sodium etch) treatment or plasma activation to create the micro-roughened surface chemistry needed for reliable copper adhesion.
This step adds cost and requires specific process capability at your fabricator. Not all standard PCB shops have sodium etch lines. Qualifying your fabricator for PTFE processing before committing a design to production is a step that avoids expensive surprises.
Drilling
PTFE composites drill differently from FR-4. The relatively soft matrix can cause issues with drill wander, burring, or smearing if parameters are not adjusted. Recommended practice includes:
Using sharp, specialized drill bits (typically carbide, with higher rake angles)
Running lower feeds and higher spindle speeds than FR-4 defaults
Chemical etching of copper on IsoClad 933 follows standard PTFE laminate practices. The key variable is that the substrate is more dimensionally stable than many other PTFE products due to the higher glass content — but it still moves more than FR-4 over the temperature ranges seen during processing. For tight-registration multi-layer builds, use artwork compensation based on measured material movement and consider pin registration throughout the process.
Soldering and Assembly
IsoClad 933 is compatible with standard soldering temperatures. PTFE materials have high melting points and do not degrade under typical reflow conditions (peak temperatures of 250–260°C). However, the low thermal mass and relatively poor thermal conductivity of PTFE materials means the board can reach peak temperature quickly — profile validation on actual hardware is always advisable.
Available Thicknesses and Ordering Information
IsoClad 933 is stocked by specialty RF laminate distributors. The standard product code format from Arlon references the thickness and dielectric constant in the part number — for example, the 933B designation family covers a range of thicknesses in the 1 oz copper configuration. Pricing as of publicly available data runs from approximately $44 to $115 per square foot depending on thickness, with quantity breaks for larger orders.
When ordering IsoClad products, it’s important to specify the dielectric constant in your purchase order, as the product designation can refer to the overall laminate family. Your supplier can confirm the correct part number for the specific thickness and copper cladding weight you need.
Useful Resources for Engineers Working With Arlon IsoClad 933
Resource
Description
Link
Arlon IsoClad Datasheet (via Midwest PCB)
Full property table including electrical and mechanical data
IsoClad 933 in the Broader Arlon Product Ecosystem
Understanding where IsoClad 933 fits within Arlon’s broader microwave laminate portfolio helps you avoid over-specifying or under-specifying. Arlon — now part of Rogers Corporation — offers several product families that serve the RF and microwave space.
The DiClad series uses woven fiberglass reinforcement in a unidirectional ply arrangement, covering a wider range of Dk values from about 2.17 to 2.60. Dimensional stability is good but not isotropic in the electrical sense.
The CuClad series extends the DiClad concept with cross-plied woven glass for improved dimensional control and better in-plane isotropy, though still not matching the random fiber distribution of IsoClad.
The CLTE family brings in ceramic filler to address the Z-axis CTE problem for through-hole reliability. Its nominal Dk of 2.98 puts it in a different design window than IsoClad 933.
The AD series represents Arlon’s newer-generation materials using PTFE with microdispersed ceramic and commercial-grade glass, targeting cost-sensitive high-volume commercial applications.
Within this ecosystem, IsoClad 933 occupies the “traditional, highest-performance nonwoven PTFE” category. It’s not the newest material in the portfolio, but its properties are well-characterized, its processing behavior is understood by experienced PTFE fabricators, and its performance is predictable in ways that matter for production reliability.
Common Design Mistakes When Using PTFE Laminates Like IsoClad 933
Working with microwave laminates is an area where the gap between datasheet knowledge and practical experience shows up clearly. Here are the errors that cost people time and money on real projects:
Using the wrong Dk value in simulation: The datasheet Dk of 2.33 is measured at 10 GHz per IPC TM-650. Your EM simulator may need a slightly adjusted effective Dk value that accounts for copper surface roughness and the test method differences between stripline and microstrip measurements. Always validate transmission line impedance with a network analyzer on a test coupon before committing to a full board.
Underestimating copper roughness effects: At high frequencies, the surface texture of the copper foil creates additional loss beyond what bulk resistivity predicts. Standard ED copper works well for many IsoClad 933 applications, but above 10–15 GHz, specifying low-profile or rolled copper can meaningfully improve insertion loss.
Choosing a fabricator without PTFE experience: This cannot be overstated. A shop that only processes FR-4 will not have the sodium etch line, the appropriate drill parameters, or the process documentation to handle IsoClad 933 correctly. The resulting boards may look fine visually but fail electrically due to adhesion issues in vias or Dk variations from poor material handling.
Ignoring moisture absorption: While PTFE has very low moisture uptake compared to epoxy-glass laminates, any moisture absorbed during storage can affect both Dk and Df slightly. Store IsoClad 933 panels per Arlon’s recommendations (cool, dry, away from UV light), and bake out panels before processing if they’ve been stored for extended periods.
Frequently Asked Questions About Arlon IsoClad 933
Q1: What frequency range is Arlon IsoClad 933 rated for?
IsoClad 933 does not have a hard upper frequency limit in the traditional sense — PTFE-based materials inherently maintain low dielectric loss to very high frequencies. The material is routinely used from below 1 GHz up through X-band (8–12 GHz) and into Ku-band (12–18 GHz). The published electrical properties at 10 GHz (Dk = 2.33, Df = 0.0016) are representative of in-band performance. Above Ka-band, alternative materials with even lower loss and tighter process controls may be preferred, but IsoClad 933 is a workhorse substrate for the commercial microwave frequency range.
Q2: Can Arlon IsoClad 933 be processed with standard PCB equipment?
Partially. The copper etching, imaging, and solder mask processes are compatible with standard equipment. However, through-hole plating requires sodium etch or plasma treatment of the PTFE surface before electroless copper deposition — this step is not present in standard FR-4 processes. Drilling parameters also need adjustment. Fabricators with PTFE process experience will have these steps dialed in; standard shops typically will not.
Q3: How does IsoClad 933 compare to Rogers RT/duroid 5880?
RT/duroid 5880 (Dk = 2.20, Df = 0.0009) has lower dielectric loss and is the preferred choice for the most demanding low-loss applications, particularly at millimeter-wave frequencies and in aerospace/defense applications where cost is secondary. IsoClad 933 offers slightly higher Dk (2.33) and Df (0.0016), but provides better dimensional stability due to its higher glass content, and is typically more cost-effective. For most commercial applications at X-band and below, the performance difference is manageable and IsoClad 933’s mechanical advantages can tip the balance.
Q4: Is IsoClad 933 suitable for multilayer PCB construction?
Yes, IsoClad 933 can be used in multilayer constructions. It is available as a core laminate and compatible bonding plies (prepregs) are available for layer-to-layer adhesion. The higher fiberglass content versus IsoClad 917 improves registration between layers during the pressing cycle. That said, multilayer PTFE stack-ups require careful lamination process development — PTFE behaves differently from FR-4 under heat and pressure in a lamination press, and your fabricator needs specific experience with PTFE multilayer processing.
Q5: Where can I buy Arlon IsoClad 933?
IsoClad 933 is stocked by specialty RF laminate distributors including HD Communications, Midwest PCB (who hosts the official datasheet), and several industrial electronics distributors. Since Rogers Corporation acquired Arlon, the material is also referenced through Rogers’ distribution network. Pricing varies by thickness and quantity — roughly $44–$115/sq ft for small orders. For production quantities, contacting Rogers Corporation or a certified distributor directly will give you current pricing and lead times.
Summary: Is Arlon IsoClad 933 Right for Your Design?
Choose IsoClad 933 when:
You need a nonwoven PTFE substrate with truly isotropic Dk for consistent transmission line performance across all trace orientations
Operating frequency is in the range of roughly 1–20 GHz and Df of 0.0016 is acceptable
Dimensional stability and mechanical strength during fabrication are priorities
The circuit may need to be formed or bent (conformal applications)
You want a well-characterized, time-proven material with a known fabrication process
Look elsewhere when:
You need the absolute minimum loss available and can accept lower mechanical rigidity (consider IsoClad 917 or RT/duroid 5880)
The design sees significant thermal cycling and through-hole reliability under CTE stress is the primary concern (consider CLTE)
Your fabricator cannot process PTFE and you need standard FR-4-compatible methods (consider RO4350B)
The application is above 20–30 GHz and requires millimeter-wave-grade performance
Arlon IsoClad 933 has earned its position in the RF engineer’s toolkit over decades of real-world deployment. Its combination of isotropic electrical behavior, solid dissipation factor at microwave frequencies, and improved mechanical stability within the nonwoven PTFE family makes it a pragmatic, well-understood substrate for the bread-and-butter of commercial and defense microwave circuit work. It’s not exotic, and that’s largely the point — when you need something that works reliably from drawing board to volume production, reliable and well-characterized usually wins.
Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
