CLTE Copper Clad Laminate: High-Performance High-Frequency Circuit Material

CLTE™ is a high-frequency circuit laminate engineered for applications demanding exceptional dimensional stability, low thermal expansion, and consistent electrical performance. As a proven PTFE-based material, it is particularly well-suited for advanced radio frequency (RF) and microwave circuits, including embedded resistor technologies, ground-based and airborne communications systems, and radar applications.

A standout feature of CLTE is its excellent dimensional stability and exceptionally low planar Coefficient of Thermal Expansion (CTE). With typical CTE values of 9.9 ppm/°C (x-direction) and 9.4 ppm/°C (y-direction), it minimizes dimensional changes during temperature fluctuations, ensuring reliable registration for multilayer boards and precise performance of embedded passive components. This stability, combined with its low Dissipation Factor (0.0021 @ 10 GHz), supports high-efficiency signal transmission with minimal loss.

The laminate offers robust mechanical and thermal reliability. It maintains strong copper peel strength (1.2 N/mm after thermal stress) and exhibits high thermal resistance, with a Time to Delamination exceeding 60 minutes at 288°C and a Decomposition Temperature (Td) of 538°C. These properties ensure durability in demanding thermal environments and during assembly processes like soldering.

Standard Properties Table

Properties		Typical Values1		Units	Test Conditions		Unit
		CLTE	CLTE-XT
Electrical Properties
Dielectric Constant (process)		2.98	See Table		23˚C @ 50% RH	10 GHz	IPC TM-650 2.5.5.5
			Below	-
Dielectric Constant (design)		2.98	2.93	-	C-24/23/50	10 GHz	Microstrip Differential Phase Length
Dissapation Factor		0.0021	0.001	-	23˚C @ 50% RH	10 GHz	IPC TM-650 2.5.5.5
Thermal Coefficient of Dielectric Constant		6	-8	ppm/˚C	-50 to 150˚C	10 GHz	IPC TM-650 2.5.5.5
Volume Resistivity		1.4 X 10⁹	4.25 X 10⁸	Mohm-cm	C-96/35/90	-	IPC TM-650 2.5.17.1
Surface Resistivity		1.30 X 10⁶	2.49 X 10⁸	Mohm	C-96/35/90	-	IPC TM-650 2.5.17.1
Electrical Strength (dielectric strength)		1100	1000	V/mil	-	-	IPC TM-650 2.5.6.2
Dielectric Breakdown		64	58	kV	D-48/50	X/Y Direction	IPC TM-650 2.5.6
PIM		-	-	dBc	-	50 ohm 0.060"	43dBm 1900 MHz
Thermal Properties
Decomposition Temperature (Td)		538	539	˚C	2hrs @ 105˚C	5% Weight Loss	IPC TM-650 2.3.40
Coefficient of Thermal Expansion - x		9.9	12.7	ppm/˚C		-55˚C to 288˚C	IPC TM-650 2.4.41
Coefficient of Thermal Expansion - y		9.4	13.7	ppm/˚C		-55˚C to 288˚C	IPC TM-650 2.4.41
Coefficient of Thermal Expansion - z		57.9	40.8	ppm/˚C		-55˚C to 288˚C	IPC TM-650 2.4.41
Thermal Conductivity		0.5	0.56	W/(m.K)		z direction	ASTM D5470
Time to Delamination		>60	>60	minutes	as-received	288˚C	IPC TM-650 2.4.24.1
Mechanical Properties
Copper Peel Strength after Thermal Stress		1.2 (7)	1.7 (9)	N/mm	10s @288˚C	35 μm foil	IPC TM-650 2.4.8
				(lbs/in)
Flexural Strength (MD, CMD)		92.4, 86.9 (13.4, 12.6)	40.7, 40.0 (5.9, 5.8)	MPa (ksi )	25˚C ± 3˚C	-	ASTM D790
Tensile Strength (MD, CMD)		73.8, 71.0 (10.7, 10.3)	29.0, 25.5 (4.2, 3.7)	MPa (ksi )	23C/50RH	-	ASTM D638
Flex Modulus (MD, CMD)		8122, 7984 (1178, 1158)	3247, 3261 (471, 473)	MPa (ksi )	25˚C ± 3˚C	-	ASTM D790
Dimensional Stability (MD, CMD)		-0.07, -0.02	-0.37, -0.67	mm/m	4 hr at 105˚C	-	IPC-TM-650 2.4.39a
Physical Properties
Flammability		V-0	V-0	-	-	C48/23/50 & C168/70	UL 94
Moisture Absorption		0.04	0.02	%	E1/105+D24/23	-	IPC TM-650 2.6.2.1
Density		2.31	2.17	g/cm³	C-24/23/50	-	ASTM D792
Specifc Heat Capacity		0.6	0.61	J/g˚K	2 hours at 105˚C	-	ASTM E2716
NASA Outgassing	Total Mass Lost	0.02	0.02	%	-		ASTM E595
	Collected Volatiles	0	0	%

Standard Specifications:

Electrical Properties:

• Dielectric Constant (Dk): 2.98 (both process and design values @ 10 GHz).
• Dissipation Factor (Df): 0.0021 @ 10 GHz.
• Volume Resistivity: 1.4 x 10⁹ Mohm-cm.
• Electrical Strength: 1100 V/mil.

Thermal Properties:

• CTE (x/y/z): 9.9 / 9.4 / 57.9 ppm/°C.
• Thermal Conductivity: 0.5 W/(m·K).
• Time to Delamination: >60 minutes @ 288°C.
• Mechanical/Physical Properties:
• Copper Peel Strength: 1.2 N/mm (after 10s @ 288°C).
• Dimensional Stability: -0.07 mm/m (MD), -0.02 mm/m (CMD).
• Moisture Absorption: 0.04%.
• Flammability Rating: UL 94 V-0.
• Density: 2.31 g/cm³.

Standard Offerings:

Thicknesses: 0.0053" (0.135 mm), 0.010" (0.254 mm), 0.020" (0.508 mm), and 0.030" (0.762 mm), each with specified tolerances.

Panel Sizes: Standard sizes include 18" x 12" (457 x 305 mm) and 18" x 24" (457 x 610 mm).

Claddings: Available with various copper foils, including Electrodeposited (½ oz. and 1 oz.) and Reverse Treated Electrodeposited Copper Foil (½ oz. and 1 oz.).

In summary, CLTE laminate is a high-reliability material that combines stable electrical properties, outstanding dimensional control, and thermal robustness. Its standardized offerings in thickness, panel size, and cladding type make it a versatile and trusted choice for designing and manufacturing high-performance RF and microwave circuits. For specific configuration needs beyond the standard offerings, Rogers Corporation provides additional options through customer service.