ASTM B878-97(R2019) pdf free download

ASTM B878-97(R2019) pdf free download.Standard Test Method for Nanosecond Event Detection for Electrical Contacts and Connectors
1. Scope
1.1 This test method describes equipment and techniques for detecting contact resistance transients yielding resistances greater than a specified value and lasting for at least a specified minimum duration. 1.2 The minimum durations specified in this standard are 1, 10, and 50 nanoseconds (ns). 1.3 The minimum sample resistance required for an event detection in this standard is 10 Ω. 1.4 An ASTM guide for measuring electrical contact tran- sients of various durations is available as Guide B854. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability ofregulatory limitations prior to use. 1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Significance and Use
4.1 The tests in this test method are designed to assess the resistance stability of electrical contacts or connections. 4.2 The described procedures are for the detection of events that result from short duration, high-resistance fluctuations, or of voltage variations that may result in improper triggering of high speed digital circuits. 4.3 In those procedures, the test currents are 100 mA (620 mA) when the test sample has a resistance between 0 and 10 Ω. Since the minimum resistance change required to produce an event (defined in 3.2.1) is specified as 10 Ω (see 1.3), the voltage increase required to produce this event must be at least 1.0 V. 4.4 The detection of nanosecond-duration events is consid- ered necessary when an application is susceptible to noise. However, these procedures are not capable of determining the actual duration of the event detected. 4.5 The integrity of nanosecond-duration signals can only be maintained with transmission lines; therefore, contacts in series are connected to a detector channel through coaxial cable. The detector will indicate when the resistance monitored exceeds the minimum event resistance for more than the specified duration.
5. Apparatus
5.1 Detector—The detector used shall be an AnaTech 64 EHD, 32 EHD, or equivalent. The detector shall meet the following requirements: 5.1.1 Electromagnetic Interference (EMI)—The detector shall pass the European Community (EC) electrostatic dis- charge (ESD) requirement for computers (EN 50 082-1:94 based on IEC 801-2, ed. 2:91). The performance criteria is “1) normal performance within the specification limits;” that is, no channel is allowed to trip. Air discharge voltages shall include 2, 4, 8, and 15 kV. Contact discharge voltages shall include 2, 4, 6, and 8 kV. Detector inputs shall be protected with coaxial shorts. 5.1.2 dc Current—Each channel shall supply 100 6 20 mA when the sample being tested has a resistance between 0 and 10 Ω. 5.1.3 Input Impedance: 5.1.3.1 Direct Current (dc)—The detector source resistance (impedance) shall be 50 Ω when the sample resistance is between 0 and 10 Ω. 5.1.3.2 RF Input Impedance—A Time Domain Reflectome- ter (TDR) or Network Analyzer Time Domain Reflectometer (NATDR) shall be used to measure the reflection in percent of a (simulated) 0.5 ns risetime step when the sample direct current resistance is 10 Ω and the detector current is 100 mA. (The 10 Ω sample resistance is put on the bias port for NATDR.) An acceptable detector shall reflect less than 30 % amplitude. 5.1.4 Amplitude Sensitivity—Amplitude required to trip the detector with a 1 nanosecond duration pulse shall be no more than 120 % of the direct current trip amplitude. One nanosec- ond pulse duration shall be measured at 90 % of the pulse amplitude, and the rise and fall times shall be less than 0.5 ns. Pulse low level shall be 0 V. These shall be measured with a 1 GHz bandwidth oscilloscope and a pulse generator (see Fig. 1). 5.1.4.1 The same requirements shall be met for the 10 and 50 ns detector settings, but the pulse rise and fall times can now be less than 2 ns.