Electrical properties tests

Ste] Mechanical and electrical properties tests Hardness, electrical conductivity... 

Kum] Mechanical and electrical properties tests, thermomagnetic analysis (TMA-2 apparatus) Strength, yield point, electrical resistivity... 

Miy] Mechanical and electrical properties tests, TEM Tensile strength, yield strength, elongation, conductivity, resistance to heat-softening... 

Fuj] SEM, optical microscopy, TEM, electrical properties tests, Vickers hardness measurements Electrical resistivity and conductivity, hardness... 

Term used to describe a part immediately after it is removed from a mold and allowed cooling down. All physical, chemical, and electrical property tests are performed on nonconditioned test bars and the results recorded on the data sheets. Parts and test bars in this DAM state are felt to be their weakest in some properties as they have not had time to conditirm or relieve the molded-in stresses. 

A true material comparison is possible only when property values are determined by identical test methods under identical conditions (1). Generally speaking, physical and electrical properties of plastics and electrical insulating materials are affected by temperature and humidity. Plastic materials tested above room temperature will yield relatively higher impact strength and lower tensile strength and modulus. High humidity tends to alter the electrical property test results. Obviously, in order to make reliable comparisons of different materials and test results obtained by different laboratories, it is necessary to establish standard conditions of temperature and humidity. 

Electrical Properties. Electrical properties are important for the corrosion protection of chip-on-board (COB) encapsulated devices. Accelerated temperature, humidity, and bias (THB) are usually used to test the embedding materials. Conventional accelerating testing is done at 85°C, 85% relative humidity, and d-c bias voltage. Triple-track test devices with tantalum nitride (Ta2N), titanium—palladium—gold (Ti—Pd—Au) metallizations with 76... 

Some brief notes on the testing of electrical properties are given in the appendix at the end of this chapter. 

Since the incorporation of plasticisers into a polymer compound brings about a reduction in glass temperature they will also have an effect on the electrical properties. Plasticised PVC with a glass temperature below that of the testing temperature will have a much higher dielectric constant than unplasticised PVC at the same temperature (Figure 6.6). 

The electrical properties will also depend on the above factors as well as on the test conditions, in particular temperature, test frequency and humidity. Table 26.12 quotes ranges for figures quoted in the literature for various electrical properties. 

Electrical properties Electrostatic precipitation Direct testing... 

The efficiency of transformer oils as dielectrics is measured by electric strength tests. These give an indication of the voltage at which, under the test conditions, the oil will break down. Various national standards exist that all measure the same basic property of the oil. There is an international specification, lEC 296/1982, which may be quoted by equipment manufacturers in their oil recommendations. 

Another reason for using higher temperatures is that for an application requiring long-term exposure a candidate plastic is often required to have an RTI value higher than the maximum application temperature. The properties tested can include mechanical strength, impact resistance, and electrical characteristics. A plastic s position in a test s RTI is based on the temperature at which it still retains 50% of its original properties. 

Procedure for conditioning test specimens can call for the following periods in a standard laboratory atmosphere [50 2% relative humidity, 73.4 1.8°F (23 1°C) Adequate air circulation around all specimens must be provided. The reason for this test is due to the fact the temperature and moisture content of plastics affects different properties such as the physical and electrical properties. In order to get comparable test results at different times and in different laboratories a standard has been established. 

Aging at elevated temperatures typically involves exposing test specimens or products at different temperatures for different extended time periods. Tests are performed at room or the respective testing temperatures for whatever mechanical, physical, or electrical property is of interest. These tests of aging... 

The Underwriters Laboratories (UL) tests are recognized by various industries to provide continuous temperature ratings, particularly in electrical applications. These ratings include separate listings for electrical properties, mechanical properties including impact, and mechanical properties without impact. The temperature index is important if the final product has to receive UL recognition or approval. 

Given their radio-frequency electrical properties and nuclear magnetic resonance chemical shift components, solutions of reversed micelles constituted of water, AOT, and decane have been proposed as suitable systems to test and calibrate the performance of magnetic resonance imagers [68]. 

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