DE-104 PCB Material: Mid-Range RF Performance, Full Specs & Use Cases

When you’re putting together a BOM for a board that needs to be cost-effective, process-friendly, and reliable across a modest frequency range — without reaching for expensive specialty substrates — the DE-104 PCB material from Isola Group is one of those laminates that quietly does its job very well. It’s not going to handle 28 GHz phased array antenna boards. But for the large middle ground of consumer electronics, white goods, automotive body electronics, and industrial equipment running into the low GHz range, it’s a solid, well-characterized choice that your fabricator will have no trouble processing.

This guide covers everything a practicing PCB engineer needs to know: what the full datasheet says, what the numbers actually mean for your design, where DE-104 fits versus alternatives, and when it starts to fall short.

What Is the DE-104 PCB Material?

The DE-104 PCB material (also catalogued as DURAVER-E-Cu Quality DE104) is a low-to-mid Tg, FR-4 class copper clad laminate and prepreg manufactured by Isola Group — a global materials science company with manufacturing facilities in North America, Europe, and Asia. The product is registered under UL File Number E41625, meets IPC-4101/21 (the slash sheet for standard FR-4 with enhanced thermal properties), and is fully RoHS compliant.

The core engineering story for DE-104 is its special resin system that delivers better-than-standard Z-axis thermal resistance despite a relatively conventional Tg of 135°C. The decomposition temperature (Td) of 315°C and the T-260 delamination time of greater than 12 minutes are notably strong numbers for a material in this Tg class — a distinction worth paying attention to when specifying for lead-free or multi-reflow assembly processes.

It’s primarily available in Europe through Isola’s German operations (Isola GmbH, Düren), though it’s distributed globally through the Isola network and stocked by major European PCB fabricators.

DE-104 PCB Material: Full Datasheet Specifications

All typical values below are pulled from Isola’s official DE104 datasheet (Revision D, last updated September 2025).

Thermal Properties

Parameter	Typical Value	Unit	Test Method
Glass Transition Temperature (Tg) by DSC	135	°C	IPC-TM-650 2.4.25C
Decomposition Temperature (Td) @ 5% weight loss	315	°C	IPC-TM-650 2.4.24.6
Time to Delaminate (T-260)	>12	min	IPC-TM-650 2.4.24.1
Z-Axis CTE — Pre-Tg (α1)	70	ppm/°C	IPC-TM-650 2.4.24C
Z-Axis CTE — Post-Tg (α2)	250	ppm/°C	IPC-TM-650 2.4.24C
Z-Axis Total Expansion (50–260°C)	4.2	%	IPC-TM-650 2.4.24C
X/Y-Axis CTE Pre-Tg	16 / 13	ppm/°C	IPC-TM-650 2.4.24C
Thermal Conductivity	0.36	W/m·K	ASTM E1952
Relative Thermal Index (RTI)	130	°C	UL 94

Electrical Properties Across Frequency

Parameter	@ 100 MHz	@ 500 MHz	@ 1 GHz	@ 2 GHz	@ 5 GHz	Test Method
Dielectric Constant (Dk)	4.46	4.40	4.37	4.35	4.32	IPC-TM-650 2.5.5.x
Dissipation Factor (Df)	0.020	0.021	0.022	0.023	0.024	IPC-TM-650 2.5.5.x

Additional Electrical Properties

Parameter	Typical Value	Unit	Test Method
Volume Resistivity (after moisture)	1.3 × 10⁶	MΩ·cm	IPC-TM-650 2.5.17.1
Surface Resistivity (after moisture)	1.0 × 10⁶	MΩ	IPC-TM-650 2.5.17.1
Dielectric Breakdown	>50	kV	IPC-TM-650 2.5.6B
Arc Resistance	105	seconds	IPC-TM-650 2.5.1B
Electric Strength	54 (1350)	kV/mm (V/mil)	IPC-TM-650 2.5.6.2A

Mechanical Properties

Parameter	Typical Value	Unit	Test Method
Peel Strength — Standard Cu, after thermal stress	1.58 (9.0)	N/mm (lb/in)	IPC-TM-650 2.4.8C
Flexural Strength — Length direction	579 (84.0)	MPa (kpsi)	IPC-TM-650 2.4.4B
Flexural Strength — Cross direction	450 (65.2)	MPa (kpsi)	IPC-TM-650 2.4.4B
Tensile Strength — Length direction	393 (57.0)	MPa (kpsi)	ASTM D3039
Moisture Absorption	0.3	%	IPC-TM-650 2.6.2.1A

Compliance Summary

Certification / Standard	Status
UL 94 Flammability	V-0
UL File Number	E41625
RoHS	Compliant
IPC-4101 Slash Sheet	/21
NEMA Grade	FR-4

Understanding DE-104’s Key Properties: What the Numbers Mean

Tg 135°C — The Starting Point for Honest Evaluation

Let’s not dance around it: a DSC Tg of 135°C is on the lower end of what the industry now routinely specifies for lead-free assembly. Lead-free solder reflow peaks at 245–260°C, and the general rule of thumb is that a laminate’s Tg should be as high as practical to minimize Z-axis expansion and delamination risk during assembly. Standard FR-4 at 130°C Tg is now widely considered marginal for lead-free processes.

DE-104 at 135°C sits just above that legacy threshold — but this is where its special resin system does meaningful work. The Td of 315°C and T-260 value of greater than 12 minutes are both substantially better than what equivalent-Tg standard FR-4 grades typically deliver. That extended delamination resistance at 260°C is where DE-104 carves out its practical niche: boards that may only go through one or two reflow passes, assembled at smaller shops still dialing in lead-free processes, or products designed for the European market where this material grade has been well established for decades.

For designs that will go through multiple lead-free reflows, have double-sided SMT, or face serious rework scenarios, upgrading to a 170°C+ Tg material is the more defensible specification choice.

Dk 4.37 at 1 GHz — Frequency Range Reality Check

A dielectric constant of 4.37 at 1 GHz is firmly standard FR-4 territory. The Dk curve from 100 MHz to 5 GHz is relatively gradual (4.46 dropping to 4.32), which is reasonable behavior for this material class. For impedance-controlled traces in most digital and analog designs operating below 1 GHz, this is entirely predictable and manageable.

Where it gets limiting is above 1–2 GHz. The Df climbs from 0.020 at 100 MHz to 0.024 at 5 GHz, and signal loss on long traces at multi-GHz frequencies becomes non-trivial. That’s why calling this material “mid-range RF” is specifically accurate for the 100 MHz–1 GHz window — useful for IoT modules, low-frequency wireless interfaces, and mixed-signal industrial boards — but not a true RF substrate for anything above ~2–3 GHz where you’d need Dk below 4.0 and Df below 0.010.

Z-Axis CTE and Delamination: The Hidden Strength

The Z-axis pre-Tg CTE of 70 ppm/°C is higher than high-Tg or specialty materials, but the total Z-axis expansion of 4.2% over the full 50–260°C range is what matters practically for multilayer via reliability. Paired with that T-260 of >12 minutes, DE-104 shows better-than-average resistance to delamination at soldering temperatures for its Tg class. Isola attributes this to the engineered resin system — the same chemistry that enables this material’s thermal performance beyond what its Tg alone would suggest.

CAF Resistance and Processing Features

The DE-104 PCB material is specified as CAF resistant — an increasingly important attribute as via pitches tighten in consumer product designs. The UV-blocking characteristic and AOI fluorescence compatibility are manufacturing conveniences that matter in production: UV blocking ensures proper solder mask curing on both sides of the laminate, while AOI fluorescence compatibility reduces false-call rates during automated optical inspection.

DE-104 PCB Material: Typical Market Applications

Consumer Electronics and White Goods

This is DE-104’s home territory. Appliance control boards — dishwashers, washing machines, refrigerators, ovens — run at modest frequencies, face humid environments, and need to be manufacturable at commodity costs. The DE104 KF variant (a closely related grade with CTI 400, meaning Comparative Tracking Index of 400V) is specifically engineered for these moisture-heavy, tracking-risk applications like dishwasher control boards where electrical tracking between conductors in damp, dusty environments is a genuine failure mode.

Automotive Body Electronics

Dashboard control modules, door handle electronics, lighting controllers, and similar body electronics applications sit within DE-104’s operating envelope. These boards don’t face under-hood thermal extremes, run at frequencies well below 1 GHz, and benefit from the material’s documented CAF resistance and good moisture performance.

Industrial Instrumentation and Control

For process instrumentation, relay boards, PLC I/O modules, and measurement equipment running in the low-MHz range, DE-104’s combination of UL certification, IPC-4101/21 compliance, strong mechanical properties (flexural strength of 579 MPa in the length direction), and standard FR-4 processability makes it a reliable, approved-vendor-list candidate without specification risk.

PCBs for Telecommunications Terminal Equipment

Lower-speed telecom line cards, POTS terminal equipment, and DSL access equipment that doesn’t push multi-GHz signaling can use DE-104 effectively. The material’s documented insulation resistance performance after moisture conditioning is relevant for telecom CPE equipment that may sit in uncontrolled environments.

DE-104 PCB Material vs. Key Alternatives

Property	DE-104 (Isola)	Standard FR-4 (130°C)	Isola 370HR	Isola FR408HR
Tg (DSC)	135°C	~130°C	180°C	190°C
Td	315°C	~300°C	340°C	360°C
T-260	>12 min	<5 min (typical)	>30 min	>60 min
Dk @ 1 GHz	4.37	~4.5–4.8	~4.2	3.68
Df @ 1 GHz	0.022	~0.020–0.025	~0.017	0.0092
CAF Resistant	Yes	Variable	Yes	Yes
Lead-Free Suitability	Limited (single reflow)	Marginal	Strong	Excellent
UL Rated	Yes (E41625)	Varies	Yes	Yes
Primary Strength	Cost, T-260, AOI	Low cost	Thermal + CAF balance	High-speed + thermal

The table shows clearly that DE-104 punches above its Tg in the thermal stability columns (T-260 and Td) while being outclassed by 370HR and FR408HR in high-Tg and signal integrity performance. It’s not trying to compete with those materials — it fills a different cost-performance tier.

Glass Availability and Material Forms

One practical engineering note: DE-104 is offered in E-glass, square weave glass, and mechanically spread glass variants. Spread glass matters for designs with tight differential pair routing at frequencies above a few hundred MHz, as standard woven glass can introduce impedance variation and skew from glass weave effects. If you’re routing GHz-frequency differential pairs in a DE-104 design, specifying spread glass fabric is worth the conversation with your fabricator.

Available thickness range: 2 to 93 mil (0.05 to 2.4 mm) laminate. Copper weights of ½ oz, 1 oz, and 2 oz (18, 35, and 70 µm) are standard, with thinner copper foil available. HTE Grade 3 copper foil is the standard specification.

Useful Resources for DE-104 PCB Material

Resource	Description	Link
Isola DE104 Official Product Page	Product overview, Dk/Df specs, download datasheet	isola-group.com
Isola DE104 Full Datasheet PDF	Complete typical values table, Rev. D (Sep 2025)	pwcircuits.co.uk/de104
IPC-4101 Standard	Base material specification including Slash Sheet /21	ipc.org
CircuitData Material Database	Open-source searchable CCL properties and comparison	materials.circuitdata.org
IPC-TM-650 Test Methods	Full test method library used in DE-104 datasheet	ipc.org/TM-650
Doosan PCB Laminate Reference	Alternative CCL options and sourcing for PCB fabrication	PCBSync Doosan

5 Frequently Asked Questions About DE-104 PCB Material

Q1: Is the DE-104 PCB material suitable for lead-free assembly?

It can handle lead-free assembly with the right process management, but it is not the strongest choice for demanding lead-free applications. The Tg of 135°C is low relative to lead-free reflow peak temperatures of 245–260°C. However, the Td of 315°C and T-260 delamination time of >12 minutes give it more margin than a bare Tg number suggests. For boards with a single reflow pass and standard copper weight, DE-104 can work. For double-sided SMT, multiple reflow cycles, or high-layer-count multilayers, specifying Isola 370HR (Tg 180°C) or a similar high-Tg FR-4 material is the more reliable path.

Q2: What frequency range is DE-104 genuinely suitable for?

DE-104 covers the 100 MHz to approximately 1–2 GHz range adequately. At 1 GHz its Dk is 4.37 and Df is 0.022 — workable for controlled-impedance traces in digital boards, low-speed wireless interfaces, and industrial analog circuits. Above 2 GHz, the rising Df (0.024 at 5 GHz) starts generating meaningful signal loss on longer traces. For designs pushing past 2–3 GHz with signal integrity requirements, materials with Df below 0.010 are appropriate — Isola FR408HR (Df 0.009 at 10 GHz) is the natural next step up within the Isola family.

Q3: What is the difference between DE-104 and DE-104 KF?

The DE-104 KF is a closely related variant with an elevated CTI (Comparative Tracking Index) of 400V, qualifying it for applications where electrical tracking through contamination, moisture, or conductive dust is a primary failure concern. This makes DE-104 KF specifically suited to appliance boards in dishwashers, washing machines, and similar damp-environment products where standard CTI ratings are insufficient. The base DE-104 and DE-104 KF are otherwise similar in processing and construction.

Q4: Does DE-104 require any special fabrication process adjustments?

No — this is one of DE-104’s practical advantages. The datasheet explicitly states it is listed as FR-4 and processes using standard parameters. Standard drill feeds and speeds, conventional permanganate or plasma desmear, and normal multilayer lamination press cycles all apply without modification. The UV-blocking property means your solder mask exposure process will behave consistently. The AOI fluorescence compatibility reduces inspection complications on the production line. If your fabricator can build standard FR-4 multilayers, they can build with DE-104.

Q5: Can DE-104 be used in multilayer PCB designs, and are there layer count limits?

DE-104 is available in multilayer (ML) grade, and there is no inherent layer count ceiling from the material itself. However, practical considerations apply: for high-layer-count designs (10+ layers), the Z-axis CTE and total Z-expansion properties become more significant for via reliability under thermal cycling. At that level, the T-260 performance of >12 minutes is reassuring, but if the design also requires multiple lamination cycles (sequential lamination for HDI builds), the material’s moderate Tg makes it less ideal compared to 180°C Tg alternatives. For 2–8 layer designs in standard single-lamination builds, DE-104 multilayer performs reliably.

Summary

The DE-104 PCB material earns its place in the engineer’s materials list as a cost-effective, process-friendly FR-4 class laminate with genuinely better thermal delamination resistance than its 135°C Tg suggests. Its Dk/Df curve across 100 MHz to 5 GHz makes it a functional mid-range RF substrate for everyday digital and mixed-signal designs where signal frequencies stay below 2 GHz and where premium low-loss materials would be over-engineering the solution. The UV blocking, AOI compatibility, CAF resistance, and standard FR-4 processing make it a fabrication-friendly choice. Know its limits — it’s not a high-Tg board for demanding lead-free assembly, and it won’t carry 5 GHz signals efficiently — and it will serve your designs well within those boundaries.