Simplify Dielectric Constant measurement in accordance with ASTM D 150, IPC-TM-650 and IEC-60250 standards using the 7660 Precision LCR Meter and the RDC-1 Rigid Dielectric Cell.

The 7660 Precision LCR Meter with the RDC-1 Rigid Dielectric Cell was specifically designed to make Dielectric Constant and Dissipation Factor measurements in accordance with IEC-60250 and ASTM D 150.

Key Features of the RDC-1 Rigid Dielectric Cell:

• Designed for rigid flat materials up to 38 mm (1.50 inches) in diameter and 10 mm (0.40 inches) thick.
• Precision micrometer adjustment for exact electrode spacing
• Dual-electrode design with a guard for accurate high-frequency testing
• Includes 5 mm and 38 mm interchangeable electrodes to accommodate different sample sizes
• Comes with a PTFE Calibration Standard for system verification before testing

The 7660 Precision LCR Meter is ideal for repeatable and precise measurements of dielectric properties by:

• Supports a broad frequency range for dielectric property measurements from 20 Hz to 2 MHz.
• Accurate and repeatable measurements of low capacitance and dissipation factor
• Simple to use and high reliability make the 7660 the choice for dielectric constant and dissipation factor measurements in accordance with ASTM D150.
• Excellent sales and applications support at IET Labs and sales@ietlabs.com.

The RDC-1 Rigid Dielectric Cell is designed for testing rigid flat materials. Material up to 38 mm (1.50 inches) in diameter and 10 mm (0.40 inches) thick can be used in the dielectric cell.

The dielectric cell is made up of two electrodes. One electrode is fixed with a grounded guard ring and the other is movable via a micrometer. The micrometer allows precise measurement of electrode spacing. The grounded guard ring reduces fringe effects to improve measurements.

The electrical connections are made via 4 BNC connectors on the base of the RDC-1. The 2.2 cm spacing allows for direct connection of the RDC-1 to most LCR meters including the 7660 Precision LCR Meter and 1920 Precision LCR Meters. Direct connection of the RDC-1 to the LCR meter minimizes errors due to cables at higher frequencies.

The RDC-1 Rigid Dielectric Cell comes with all the accessories needed to connect to the LCR Meter, perform open and short compensation, and verify the system with a Teflon standard.

The RDC-1 is delivered with the following accessories:

• Open Calibration Cover - For open circuit compensation
• Open / Short Compensation Plate - For open and short compensation
• Calibration Standard - To determine correction
• Type B 5 mm Electrode - Small electrode for smaller samples
• Type A 38 mm Electrode - Larger electrode for larger samples
• Zero Spanner
• Allen Wrench

Figure 2: RDC-1 Accessories

Step-by-Step Dielectric Measurement Process:

Compensation

Conduct open and short circuit compensation to eliminate system errors.

Sample measurement and verification

Verify performance using the PTFE Calibration Standard with a known dielectric constant of 2.02.

Insert the material sample into the RDC-1 cell and adjust the micrometer-controlled electrode.

Measure capacitance (Cp) and dissipation factor (Df) of the material using the 7660 LCR Meter.

Remove the sample, return the micrometer to the previous setting and measure capacitance (Cp) and dissipation factor (Df) of air using the 7660 LCR Meter.

Data calculation (per ASTM D150 Standard)

Use the measured capacitance values to calculate the dielectric constant (k) and dissipation factor (Df) of the material using standard formulas.

Open & Short Compensation

It is very important to perform an OPEN and SHORT circuit zero with the instrument before making measurement. Figure 3 illustrates the preferred method to accomplish short using the RDC-1 and the short compensation plate.

Figure 3: Use of Short Compensation Plate

Figure 4 illustrates the preferred method to accomplish open compensation using the compensation plate with the open cover.

Figure 4: Use of Open Compensation Plate with Open Cover

To perform measurements

First the sample is inserted in the cell and the electrodes closed with the micrometer until they just touch the sample. Do not force the electrodes against the sample as this can damage the cell. Turn the micrometer with a light finger touch. Record the micrometer setting, or zero the micrometer, as hm.

Set the instrument to measure parallel capacitance and measure the capacitance and dissipation factor of the sample as Cxm and Dxm.

Open the electrodes and remove the sample. Then close the electrodes to the same micrometer reading hm, or back to zero if micrometer was zeroed.

Measure C (parallel) and D of empty cell as Ca and Da.

Calculate Kx and Dx of the sample from:

Kx = (1.0005) Cxm/Ca and Dx = |Dxm| - |Da|

The factor 1.0005 in the formula for Kx corrects for the dielectric constant of (dry) air. Subtracting Da from Dxm removes any constant phase error in the instrument. For even better D accuracy, adjust the electrode spacing until the measured capacitance is approximately equal to Cxm and then measure Da.



A Teflon sample is included for checking measurements on the RDC-1. The Teflon Standard has a dielectric constant value of 2.0 and dissipation factor of less than 0.0002 over a broad frequency range from 1 kHz to 2 MHz.

More information on the 7660 Precision LCR Meter and the RDC-1 Rigid Dielectric Cell can be found at the NEW Application Note Dielectric Constant and Dissipation Factor on materials according to ASTM D150, and IEC-60250 using the 7660 Precision LCR Meter and RDC-1 Rigid Dielectric Cell

Here is an example of a laboratory that uses the 7600 Precision LCR Meter to perform testing on polymer materials to ASTM D 150 and IEC 60250. Intertek Plastics Technology Laboratory ASTM D 150 and IEC 60250