1. Barth CDM Measurement Components Improve Repeatability With Accurate Characteristics “Measure what is measurable; make measurable what is not” Galileo
The new CDM tester components presented here are the result of our last 3 years efforts to improve this measurement system.
Improving test repeatability (and the standard) however, requires that each component in the CDM measurement chain be specified to a known level of accuracy.
The existing current sensors have many measurement errors and are the basic cause of variations in CDM data.
The verification modules to a somewhat lesser extent also have errors, however their errors are hidden by those of the current sensors.
The only way to reduce data variations between all testers is to replace the existing components with new units that can be accurately measured to meet new specifications.
Exhibitor Showcase 9/13/2016

2. CDM Data Suffered Large Variations Too Many Years
Different CDM Standards have different peak current parameters
Data Within Each Standard are Different
We have designed new components
They and new Specs will Fix this problem
Industry Council White Paper #2, Appendices A, B & especially C, clearly describes the problems, of different data produced by different testers.
I doubt that anyone here is pleased with the repeatability in today’s CDM testing.
Exhibitor Showcase 9/13/2016

3. Change in Current Sensor Design
Produced Excessive Variations
Increased JEDEC and ESDA differences
Resonant Cavity raised 1 GHz response
But it added:
Ringing of discharge waveform &
Questionable affects in CDM Failure levels
Some years ago the CDM current sensor design was changed from a disk resistor (that was no longer available) to a ring of garden variety, or common chip resistors mounted on a FR4 disk.
The questionable high frequency characteristics of FR4 used to support the resistors produced widely variable high frequency characteristics.
Its high frequency characteristics could have been identified with the 50 ohm coaxial adapter we developed many years ago for the current sensor;
Unfortunately its pulse response was only verified with the original method of combining all the measurements components together. That included the 1 GHz scope
This fundamental neglect of measurement accuracy began a long process of increasing variations in CDM measurements.
Exhibitor Showcase 9/13/2016

4. Model 4106 Current Sensor RCDM3
Very early we recognized these basic measurement errors and spent the last three years developing a new current sensor shown here;
Our new current sensor with uniform frequency response characteristics is a direct replacement upgrade of the existing units in the RCDM3 CDM tester.
An additional model is being designed for the Orion CDM tester and can be adapted to other CDM testers
Users will recognize the advantages of universal repeatability that can be achieved through uniformly accurate measurement characteristics.
We will explain the advantages of uniform frequency response and the value of a true one ohm resistance to more accurately identify device failure levels, in the full paper.
Exhibitor Showcase 9/13/2016

5. Model 4181 Verification Module
We also developed a new type of verification module that uses alumina as the dielectric.
Its fixed terminals provides known and tight tolerance high frequency capacitance values.
If you are going to improve a standard, the standard capacitor used to verify the tester operation should have a fixed, calibrated value that is accurate at the frequency range where it operates.
The three different value alumina dielectric capacitors are mounted on this metal shell.
It fits directly over the FR4 insulators on the charge plate and eliminates its poor dielectric properties from the verification discharge.
The improvements in using alumina over FR4 as the dielectric material will be described in the paper following this presentation.
Exhibitor Showcase 9/13/2016

6. Positioning Model 4181A Verification Modules
This shows how our new (triple ) Verification module is positioned on the RCDM3 charge plate.
When in position, it encloses the FR4 insulators inside a metal cavity so its lousy (Less than Ideal) dielectric characteristics are isolated from the verification module discharge circuit.
The back side of the metalized alumina disk (1.0 inch / 2.54 cm) diameter is connected directly to the aluminum charge plate
This assembly places the charged alumina capacitors in location for discharge, in the same manner as the JEDEC coins; but without FR 4
We have added a third alumina capacitor (1.0 pF) to the two JEDEC value capacitors of 6.8 and 55 pF.
Adding this third 1 pF capacitor to the verification module provides an accurate source to identify the discharge current waveform for small devices.
Offset In Place
Exhibitor Showcase 9/13/2016

7. Changes to CDM Standards
Making CDM what it should be
New frequency specifications for:
Current Sensor response
Verification Module (Reference Capacitor)
Scope Response (Bandwidth and roll-off)
Coaxial cable attenuation
END
These are the four components in the CDM tester that determine its measurement accuracy for the verification process.
These measurement issues need changing with new specs for CDM standards.
The scope response should have sufficient bandwidth to accurately measure the voltage waveform parameters and will be more thoroughly described in the paper.
The coaxial cable has a variable attenuation with frequency but it will remain relatively constant. (Unless the cable has been crunched in the machine’s movement.)
*Repeatability can only be provided when measurements are accurate, because they are directly related and cannot be separated.
We will be pleased to discuss purchasing these two CDM tester accessories and trade in discounts at our Booth #202 in the exhibit hall.
Exhibitor Showcase 9/13/2016