Complete List of PTFE (F4B) Sheet Models: 15 Series, Naming Rules Included

Lists of F4B sheet models circulate as bare part numbers — F4BM255, F4BME220, F4BTM350, WL-CT615 — with nothing that says what the letters change or which numbers are current. This page reorganizes the full fifteen-series catalog around the naming rules, so a part number can be read before it is quoted: what the branch letters mean, which grades supersede the legacy names, where the Dk ladder runs, and what to confirm against a datasheet before a number goes on a drawing.

Every designation in this catalog decomposes the same way, and reading it correctly answers three questions before any datasheet is opened: what the dielectric is, what the copper is, and what the dielectric constant is.

The number rule is the fastest triage tool in RF sourcing: the number is the Dk. F4BM220 is a Dk 2.20 laminate, WL-CT615 a Dk 6.15, F4BTMS1000 a Dk 10.0. Two caveats apply: the tolerance and Df behind the number differ by branch (section 2 to 4), and for the extended series outside the published ladder the per-grade loss data should be confirmed against the current datasheet rather than assumed. The family-level view of what each branch is for is in the F4B family map.

The F4BM series is the volume core of the catalog — PTFE plus woven glass cloth with electrodeposited copper, nine Dk grades from 2.17 to 3.00, full published electrical data:

UL 94 V-0 rating and water absorption at or below 0.08 % (F4BM220 confirmed data) hold across the ladder. Note the pattern the tolerance column shows: ±0.04 at the bottom of the Dk range loosens to ±0.06 at 3.00 — one more reason to climb only as high as the layout actually requires. The 2.20 grade, being the most specified, has its own page: F4BM220 specifications and impedance arithmetic.

F4BME217 through F4BME300 mirror the F4BM ladder one-for-one — same Dk, same Df, same temperature coefficients, same tolerance. The only physical difference is the foil: standard electrodeposited copper is replaced with reverse-treated (RTF) copper, bonded smooth-side to the dielectric.

That single change exists for one electrical reason: passive intermodulation. The flat copper-dielectric interface of an RTF foil lowers PIM in antenna feed networks, which is why F4BME is the base-station antenna branch and F4BM is everything else. Any source claiming F4BME has a different Df or a ceramic-filled dielectric is wrong — the foil types and their loss consequences are compared in the PCB copper foil guide.

The T branch adds ceramic filler to the PTFE glass-cloth system, extending the Dk range past 3.00 toward 3.5 and — because ceramic loading pulls the strongly negative PTFE temperature coefficient toward zero — improving TCDk. The published models:

The per-grade Df and TCDk values for the filled branch are not published in the same detail as the F4BM ladder; before a filled grade goes on a drawing, confirm the current datasheet with the supplier. The trade the branch makes is clear from the two columns it does publish: Dk above 3.0 buys smaller geometry, Df from 0.0018 costs about 80 % more dielectric loss per inch than F4BM220.

Older drawings still call out the unlettered F4B grades. They map straight onto the current ladder — same number, same Dk intent, newer construction and tolerance control:

When a legacy number arrives on an RFQ, the substitution is grade-for-grade by number — confirm the thickness and copper weight from the drawing, not the name. First-time readers of the family usually meet it through the 2.20 grade: the F4BM220 introduction covers the naming and first-read parameters.

Beyond the four core branches, the catalog covers nine more series. The naming logic holds — prefix for the chemistry, number for the Dk where the ×100 rule applies — but the constructions diverge, and so does the data published for them:

Three practical notes on this table. F4BTMS is the series most often garbled into “F4B TMS” in secondhand articles — it is one series, ultra-fine glass with ceramic fill, and it is the only one whose ladder reaches Dk 10. TP-2 belongs to the composite-dielectric branch, not to F4B — designs that list it as an F4B variant are misfiling it; the distinction is laid out in the TP-2 page. And the WL-PP entries are bonding materials, the companion layers that make F4B-to-FR-4 hybrid stacks possible — the press windows they enable are covered in the F4B hybrid lamination guide.

A part number names the dielectric; an order needs four more fields, and a quote that skips them is pricing a different board:

The thickness field deserves emphasis because it is the one the naming system cannot carry: the same F4BM220 at 0.127 mm and at 1.5 mm are different impedance problems, different drill problems, and different cutting plans — the handling rules are in the substrate cutting guide.

The previous version of this page was the catalog in its raw form — fifteen numbered lines and a company blurb. Three specific problems were fixed:

No naming rules. The list gave F4B255 and F4BM255 side by side with no indication that one is the predecessor of the other; sections 1 and 5 now carry the decode and the substitution map. No construction data. Fifteen series were indistinguishable; the extended-series table now separates PTFE glass cloth, ceramic-film builds, composite dielectrics, non-PTFE polymer systems and bonding materials — five different procurement decisions that a flat list collapsed into one. A stale company claim. “15 years of expertise” was hardcoded in the text; XCE PCB has been building high-frequency boards since 2009, and dates that age with the page belong in the footer, not the copy.

Where a series sits in a full material decision — against Rogers grades, against cost targets, against a loss budget — is a framework question, and the material selection guide walks it. The processing consequences of the ceramic-filled and composite-film branches (desmear chemistry, press windows) are treated grade-specifically in the F4BM220 processing page.

The F4B catalog is one naming system across fifteen series, and once the segments are decoded the list stops being a catalog and becomes a menu: the branch letters say what the dielectric and the foil are made of, the number says the Dk, and the series table says what data is published and what must be confirmed. The F4BM nine-grade ladder (Dk 2.17–3.00, Df 0.0010–0.0018) is the documented core; F4BME duplicates it on RTF copper for PIM; F4BTM and the F4BTMS fine-glass series extend it toward Dk 10 for compact geometry; the WL and TP/TF/TFA series cover composite and non-PTFE systems with bonding companions for hybrid stacks.

XCE PCB fabricates all of them: 2 to 72 layers, panels to 600×1200 mm, impedance ±10 % standard with coupon-verified tighter windows, PTFE desmear and hybrid press capability in-house, samples in as fast as 24 hours, 5,000 m² of plant with 80+ engineers and over 10,000 high-frequency builds since 2009, inspected to IPC-A-600G and IPC-6015. Send the part number — or just the Dk, thickness and frequency — and the series can be confirmed before anything is quoted.