Prostat PRF-911, Operation Manual

PRF-911 Concentric Ring 

3

I. Introduction 

The PROSTAT PRF-911 Concentric Ring and PTB-920 Dual Test Bed work together, 
and in conjunction with the Prostat PRS-801 and PRS-812 Resistance Instruments for 
measuring Surface Resistance and Volume Resistivity of materials. The size, portability 
and construction make this fixture system convenient for auditing flat materials and films 
in the field. The concentric Ring with one 5 Ib electrode weight on top 

approximates

currently recommended resistance and resistivity measurement procedures. 

A.   PRF-911 Concentric Ring consists of a spring loaded center electrode (D

1

) and an 

outer electrode ring (D

2

). Both electrodes are covered with highly conductive rubber. 

1. Direct surface resistance measurements generally conform to the guidelines as 
    outlined in the ESD STM 11. 11-2001 Surface Resistance test method. 
 
2. The dimensions of the fixture allow estimation of surface resistivity in 

ohms/square. This estimate is obtained by multiplying surface resistance results 

    obtained herein by 10 times, i.e., adding one order of magnitude. 
 
3. The fixture connections allow the device to be used for making Volume Resistivity 
    measurements generally described in ASTM D-257 and ESD STM 11.12-2000 

Volume Resistance Measurements. The fixture correction for the area of its center 
electrode (D

1

) is 6.9 cm

2

. 

B.   The PTB-920 Dual Test Bed consists of a four inch metal test bed laminated to an 

insulated test bed. 

1.   The insulated acrylic surface is used for surface resistance measurements made 

using the ESD STM 11.11-2001 guidelines. 

 
2.   The metal (plated aluminum) surface is used for volume resistance and resistivity 

measurements made using ESD STM 11.12-2000 guidelines. 

C.  A BNC/Dual Banana Receptacle adapter is provided for use with the PRF-911 

Concentric Ring fixture. 

II. 

Cautions & Warnings 

A.   As with any electrical device, use proper electrical precautions to avoid personnel 

shock. 

1. The PRF-911 Concentric Ring fixture operates with power input from resistance 

measurement instruments at 10 to 100 volts. An annoying shock to any person 
touching it may be possible. 

2. Although the current capability is limited, a distinct HAZARD EXISTS in the 

person's reaction to a low level electric shock. 

3. To avoid personnel shock, do not touch the electrode when power is applied.