Connector material material knowledge
When talking about the connector, it must be inseparable from the material of the connector. Different materials can bring different product performance. At the same time, the material of the connector can affect the price of the product, so understand the connector. Knowledge of material materials is necessary. The following Konnra Electronics engineers have compiled some of the materials of the connector materials. The following is a summary. Let's read them together.
As shown in Figure 1, the connector insulator is commonly used
Usually: PBT, nylon, ABS, PC, LCP and other materials are shown in Table 1, but in principle, materials with better flame resistance are used.
A.PBT material:
Generally used PBT material plus 20-30% glass fiber, with anti-cracking, anti-shock, anti-electricity, good wear resistance, low friction coefficient, good self-lubricating effect, good oil and chemical resistance. It has good dielectric strength under high temperature and high humidity. The shrinkage rate is between 0.6% and 3.0%, and the temperature resistance is about 230 °C. Good formability and flame resistance. It is a commonly used compound for connector products.
B.NYLON66, NYLON6T, PC, LCP material:
The shrinkage rate is 1.0%-0.3%, the temperature resistance is higher than PBT, the temperature is 260°C-280°C for NYLON66, the temperature is 280°C-300°C for NYLON6T, and the temperature is 290°C-320°C for LCP. However, it has a large water absorption, and is generally used for products with high temperature resistance and less PITCH (such as SMD, housing, PLCC, etc.)
C. ABS material:
It has good impact toughness, oil resistance, wear resistance, easy molding, good hardness, good rigidity and temperature resistance of about 100 °C. It is generally used in auxiliary products in connectors.
2, the common defects of injection molding and its causes
Common molding defects are as follows: plastic parts have black spots or black liquid, the surface is not smooth, flashing, plastic forming is incomplete, bubble or charred, 瘪 shape, stitching line or plastic parts are tightened in the mold and so on. . The main reason is divided into three parts: the factors of the injection molding machine, the factors of the mold, and the factors of the rubber compound.
3, Connector contact composition and performance
Bonding material: metal joint material for plugs, generally in principle brass, but the number of insertions and removals is extremely high, and the long life of phosphor bronze, beryllium copper, etc. can be used for the following industry copper Introduction of types and sexuality
1. Brass - Alloy of copper and zinc, the total color varies with the content of zinc.
A. Brass - 25~35% zinc, suitable for normal temperature processing.
B. Brass - 35% ~ 45% tin, the most suitable for normal temperature processing, the copper plate sold in the market, copper rods belong to it.
2. Bronze - An alloy of copper and tin whose color varies with the tin content.
Generally speaking, a copper alloy other than brass is called bronze.
Phosphor Bronze - Phosphorus is added to bronze, which has anti-friction properties. However, if phosphorus is too much, casting is difficult. The composition is 8 to 12% of tin and 0.5 to 1.5% of phosphorus.
The contacts can be made of any of several alloys, depending on the type of contact, the frequency of insertion and removal, and the electrical and environmental conditions under which the connector operates. Some commonly used materials and their applications are as follows:
Brass - Although brass is a material with good electrical conductivity, it is easily deformed and fatigued after repeated bending. It is usually used as a fixed contact in an inexpensive connector or as a metal part in a connector. Connectors with brass contacts should not be used where excellent flexibility is required. Of course, due to the low cost, brass can still be used as a contact in many places.
Phosphor Bronze - Phosphor bronze has a higher hardness than brass and maintains long-term elasticity. It is often used as a material for contacts that operate at temperatures below 300 °C. For most connectors with low insertion frequency or normal bending of the contacts, the use of phosphor bronze guarantees good reliability.
Bronze bronze - Bronze bronze has much better mechanical properties than brass or phosphor bronze. The beryllium bronze part can be shaped and hardened after annealing, and can actually maintain its shape forever. It is also the most resistant to mechanical fatigue. In applications where insertion and removal are frequent and where high reliability is required, beryllium bronze is recommended.
4, copper plate partial plating
Surface processing (electroplating) of the bonded body: In order to prevent corrosion and oxidation, the surface of the bonded body is smoothed and the mechanical properties of the raw material are generally subjected to electroplating processing and various plating characteristics.
(1). The gold plating thickness is 30 μ", and the Ni plating thickness in the gold plating area is 50 to 80 μ".
(2). The gold plating thickness is 3μ", and the gold plating area is 30~50μ thick.
(3) Other:
Size: Acceptance according to the size of the order item.
Exterior:
A. Unplated surface: no oil, flat strip, non-deformable, bent or stretched.
B. Electroplating surface: smooth gloss, fine particles, no pollution and deformation.
C. Baking: Freezing -55±3°C* 30' Room temperature 10'~15'→105±2°C* 30'→room temperature 10'~15.
D. Heat resistance: 85 ± 2 ° C * 2 hours.
(4). Copper plated tin
A. Salt spray testing is subject to agreement between the parties.
B. The baking test is as follows (a 0.3 item) and the tin is up to 90%.
C. Direct tin is more than 90%.
D. Heat resistance: 85 ± 2 ° C * 2 hours.
E. Copper plated copper plated with a thickness of 30~50μ".
F. tin to lead ratio of Sn / PB90: 10 or 95: 5
G. Tin plating thickness is subject to order requirements.
5, electrical performance
A. Voltage and current rating: Voltage rating involves spacing, while current rating involves contact area and tip area, which should be used according to specifications.
B. Contact resistance: When the connector is properly engaged, a current of 0.1A DC is applied between each terminal and the PIN. The contact impedance resistance is as shown in the attached table, but if the current circuit is used, it is tested with a current of 1KHZ and 1mA. The test involves the pressing portion between the wire and the joint.
C. Insulation resistance: The voltage between the terminals and the terminal and the grounding point between the terminals and the grounding point shall be as shown in the attached table.
D. Withstand voltage terminals between each other and between the terminals and grounding points, as shown in the attached table, the voltage time test should be free of abnormalities.
6, mechanical properties
(1) Insertion force: The insertion force obtained by inserting the combined speed of 25 mm to ±3 mm/min shall conform to the specifications of the insertion force.
(2). Pull out force: pull out at a speed of 25 mm ± 3 mm / min. The pull-out force of the pull-out should be in accordance with the specifications of the pull-out force.
(3) Durability: The following requirements shall be met after the insertion of the 30 owing at the speed of (10 ow/minute) and then the test.
Answer: The contact impedance is within two digits of the initial value.
B: The pull-out force should meet the specification value.
(4). Terminal holding force: Pull the terminal out of the HSG at a speed of 5 mm ± 3 mm / min. The pulling force should meet the tensile force specification.
(5). PIN retention: The PIN is pushed out of BASE at a speed of 5 mm ± 3 mm / min, and the thrust should be in accordance with the thrust specification.
(6). Terminal riveting force: Pull the terminal out of the WIRE at a speed of 5 mm ± 3 mm / min. The pulling force should meet the riveting specification value.
7, environmental performance
(1) Temperature rise of the terminal: After applying the maximum rated current of AC to the thermal equilibrium for any joint, the temperature rise value should be 30 °C or less.
(2). Vibration resistance: In the energized state of DC 0.1A, the test is carried out under the conditions of amplitude 1.5m / m and frequency 10Hz-55Hz / Min, and the X, Y and Z axes are 3 times each time and 2 hours after each axis. The following requirements:
Answer: The contact impedance should be within two of the initial value;
B: discontinuous conduction time is below 1 microsecond;
C: The appearance should be free from abnormalities.
(3). Impact resistance: Under the condition of DC 0.1A, the test is carried out under the acceleration condition of 50g and the X, Y and Z axes are 3 times. After the test, the following requirements should be met. a: I discontinuous conduction time is 1 microsecond. Below, b: the appearance should be no abnormality.
(4). Tin-like property: immersed in a tin bath of 230±50°C for 3±1 seconds from the terminal of the terminal, and immersed in a tin bath of 230±50°C for more than 95%.
(5) High temperature resistance: after being placed in a temperature and temperature bath of 85±2 °C for 96 hours, it should be abnormal and the contact resistance should be within twice of the initial value.
(6) Solder heat resistance: from the terminal body of 1.2 mm at the reference surface, 5 ± 1 second in the tin bath with immersion self-esteem 260 ± 50 °C, the insulator should be free from abnormal state such as crack deformation, and the terminal strength should be within the specification. .
(7) Moisture resistance: 96-inch in a constant temperature and humidity chamber with a temperature of 85±2°C and a humidity of 90%~95%. The test within 30 minutes after wiping the droplets should meet the following requirements:
A. The contact impedance should be within the initial two digits;
B. The insulation resistance should be above 10MΩ;
C. The appearance should be free of irregularities;
D. Should meet the requirements of withstand voltage.
(8) Salt spray test: Place the sample at 35±2°C, and the ratio of 5±1% of salt spray, 16 hours ON, 8 hours OFF for one cycle, 3 cycles after washing with water, should meet the following Requirements, one: the contact impedance should be less than twice the initial value, C: no cracks or obvious corrosion.
(9) Vulcanization gas test: After the sample is placed at 40±2° C. and the vulcanization gas with a concentration of 50±5 ppm is used for 24 hours, the contact resistance should be within twice the initial value.
8, copper conductor related detection items
(1) Wire diameter tolerance:
When 0.10 mm ≦d ≦ 0.40 mm, the tolerance is ±0.004 mm;
0.40 mm
(2). Maximum outer diameter and minimum outer diameter difference (F)
When 0.10 mm ≦d ≦ 0.40 mm, the allowable difference ̊F<0.004 mm;
0.40 mm
(3) Elongation (soft state): the total length of the taken line is 20mm
0.10 mm ≦d ≦ 0.25 mm, elongation ≧ 12%; 0.25 mm
- Elongation = (breaking time -20) / 20
9, copper conductor related performance
The most commonly used conductor in wire and cable is copper, which has comprehensive properties such as high electrical and thermal conductivity, high ductility, good strength, and can be alloyed with other metals or coated with other metals. .
Copper conductors used at temperatures up to 300 °F (or 400 °F for a short time) are coated with tin, tin-lead or pure lead and have a coating thickness of 40 to 70 micro-inch. In addition to being used to minimize oxidation, these coatings also increase solderability and corrosion protection.
Copper wires that are used continuously (or at a short time of 500 °F) at temperatures up to 400 °F are plated with a minimum of 40 micro-inch silver, which is well exposed to higher temperatures. The silver plating layer is more conductive than the tin plating layer when the frequency is sufficiently high and the skin effect becomes high.
Copper or copper-clad steel conductors are used to increase strength, but the use of these materials is always at the expense of conductivity. For example, cadmium copper, a copper alloy containing 0.5-1.0% cadmium, has a tensile strength of 150% of copper, but the electrical conductivity is only about 80% of copper. In addition, the tensile strength of the copper-clad steel wire is 150-200% of copper, but the electrical conductivity is usually only 30-40% of copper.
Aluminum alloy is lighter than copper conductors of the same specification, but its electrical conductivity is only about 60% of copper. In addition, when exposed to air, aluminum forms a surface oxide that can form an undesirable high resistance connection. Therefore, the conductors in wire and cable are often made of copper. According to the current industry, there are roughly the following types of conductors: solid conductors, stranded conductors, and braided conductors.
A. Solid conductor - . The use of solid (single strand) conductors with little wire and cable deflection is advantageous in that it is less expensive than equivalent stranded wires and is usually used for wires and cables with solid conductors. Small instrument, backplane wiring or any similar mounting line for fixed equipment.
B. Stranded conductors - Stranded conductors are used in most wire and cable to provide better flexibility and longer flex life. From a practical point of view, stranded conductors have a longer life than solid conductors. . If there is a small V-shaped crack or similar damage, it will break as soon as it is bent a few times. However, in the same operation, only a few conductors of the stranded conductor are scored or damaged, and the remaining damaged strands still provide an appropriate service life.
C. Braided Conductors - - Flat or round (tubular) braided conductors are also sometimes used in certain applications where they are more suitable than round solid or stranded cables. The braided conductor is rarely insulated because the insulating layer prevents high deflection and the ability to slightly stretch the length due to the axial pushing and pulling of the cable.
10, wire and cable insulation
The insulation of wire and cable can be divided into two basic categories - thermoset and thermoplastic, but there are so many kinds of compounds, mixtures and mixtures in each category, so that the available insulation materials are almost unlimited. Most insulating materials consist of a compound made of a synthetic rubber polymer (thermosetting) and a compound made of a synthetic material to provide special physical and electrical properties.
(1) Thermosetting insulating materials:
Thermoset materials are characterized by mechanical stresses that can be stretched, compressed, or otherwise deformed (within reasonable limits), and when this mechanical stress is removed, can "bounce back" to the original state and shape. Since thermoset insulating materials are not susceptible to thermal softening, they do not melt, flow or deform during the added thermal and electrical overloads, which cause internal heating.
(2). Thermoplastic insulation
Thermoplastic insulation is known for its excellent electrical properties and low cost. Thermoplastics are widely used as insulating materials due to their good electrical properties due to their very thin insulation thickness, especially in high voltage cables. In addition, a cable having a thin insulating layer is generally smaller in size than a cable made of a thermosetting insulating material having the same electrical properties.
Several modified thermoplastic insulating materials can be formulated with a variety of basic thermoplastic materials. Sometimes the main change is color, but most thermoplastics have different grades to meet specific temperature, strength and environmental resistance requirements. Naturally, these materials are thermoformed, thermally softened and flowed under mechanical pressure, and then retained in their deformed shape and state after cooling and/or removal of mechanical strain.
As shown in Figure 1, the connector insulator is commonly used
Usually: PBT, nylon, ABS, PC, LCP and other materials are shown in Table 1, but in principle, materials with better flame resistance are used.
A.PBT material:
Generally used PBT material plus 20-30% glass fiber, with anti-cracking, anti-shock, anti-electricity, good wear resistance, low friction coefficient, good self-lubricating effect, good oil and chemical resistance. It has good dielectric strength under high temperature and high humidity. The shrinkage rate is between 0.6% and 3.0%, and the temperature resistance is about 230 °C. Good formability and flame resistance. It is a commonly used compound for connector products.
B.NYLON66, NYLON6T, PC, LCP material:
The shrinkage rate is 1.0%-0.3%, the temperature resistance is higher than PBT, the temperature is 260°C-280°C for NYLON66, the temperature is 280°C-300°C for NYLON6T, and the temperature is 290°C-320°C for LCP. However, it has a large water absorption, and is generally used for products with high temperature resistance and less PITCH (such as SMD, housing, PLCC, etc.)
C. ABS material:
It has good impact toughness, oil resistance, wear resistance, easy molding, good hardness, good rigidity and temperature resistance of about 100 °C. It is generally used in auxiliary products in connectors.
2, the common defects of injection molding and its causes
Common molding defects are as follows: plastic parts have black spots or black liquid, the surface is not smooth, flashing, plastic forming is incomplete, bubble or charred, 瘪 shape, stitching line or plastic parts are tightened in the mold and so on. . The main reason is divided into three parts: the factors of the injection molding machine, the factors of the mold, and the factors of the rubber compound.
3, Connector contact composition and performance
Bonding material: metal joint material for plugs, generally in principle brass, but the number of insertions and removals is extremely high, and the long life of phosphor bronze, beryllium copper, etc. can be used for the following industry copper Introduction of types and sexuality
1. Brass - Alloy of copper and zinc, the total color varies with the content of zinc.
A. Brass - 25~35% zinc, suitable for normal temperature processing.
B. Brass - 35% ~ 45% tin, the most suitable for normal temperature processing, the copper plate sold in the market, copper rods belong to it.
2. Bronze - An alloy of copper and tin whose color varies with the tin content.
Generally speaking, a copper alloy other than brass is called bronze.
Phosphor Bronze - Phosphorus is added to bronze, which has anti-friction properties. However, if phosphorus is too much, casting is difficult. The composition is 8 to 12% of tin and 0.5 to 1.5% of phosphorus.
Brass - Although brass is a material with good electrical conductivity, it is easily deformed and fatigued after repeated bending. It is usually used as a fixed contact in an inexpensive connector or as a metal part in a connector. Connectors with brass contacts should not be used where excellent flexibility is required. Of course, due to the low cost, brass can still be used as a contact in many places.
Phosphor Bronze - Phosphor bronze has a higher hardness than brass and maintains long-term elasticity. It is often used as a material for contacts that operate at temperatures below 300 °C. For most connectors with low insertion frequency or normal bending of the contacts, the use of phosphor bronze guarantees good reliability.
Bronze bronze - Bronze bronze has much better mechanical properties than brass or phosphor bronze. The beryllium bronze part can be shaped and hardened after annealing, and can actually maintain its shape forever. It is also the most resistant to mechanical fatigue. In applications where insertion and removal are frequent and where high reliability is required, beryllium bronze is recommended.
4, copper plate partial plating
Surface processing (electroplating) of the bonded body: In order to prevent corrosion and oxidation, the surface of the bonded body is smoothed and the mechanical properties of the raw material are generally subjected to electroplating processing and various plating characteristics.
(1). The gold plating thickness is 30 μ", and the Ni plating thickness in the gold plating area is 50 to 80 μ".
(2). The gold plating thickness is 3μ", and the gold plating area is 30~50μ thick.
(3) Other:
Size: Acceptance according to the size of the order item.
Exterior:
A. Unplated surface: no oil, flat strip, non-deformable, bent or stretched.
B. Electroplating surface: smooth gloss, fine particles, no pollution and deformation.
C. Baking: Freezing -55±3°C* 30' Room temperature 10'~15'→105±2°C* 30'→room temperature 10'~15.
D. Heat resistance: 85 ± 2 ° C * 2 hours.
(4). Copper plated tin
A. Salt spray testing is subject to agreement between the parties.
B. The baking test is as follows (a 0.3 item) and the tin is up to 90%.
C. Direct tin is more than 90%.
D. Heat resistance: 85 ± 2 ° C * 2 hours.
E. Copper plated copper plated with a thickness of 30~50μ".
F. tin to lead ratio of Sn / PB90: 10 or 95: 5
G. Tin plating thickness is subject to order requirements.
5, electrical performance
A. Voltage and current rating: Voltage rating involves spacing, while current rating involves contact area and tip area, which should be used according to specifications.
B. Contact resistance: When the connector is properly engaged, a current of 0.1A DC is applied between each terminal and the PIN. The contact impedance resistance is as shown in the attached table, but if the current circuit is used, it is tested with a current of 1KHZ and 1mA. The test involves the pressing portion between the wire and the joint.
C. Insulation resistance: The voltage between the terminals and the terminal and the grounding point between the terminals and the grounding point shall be as shown in the attached table.
D. Withstand voltage terminals between each other and between the terminals and grounding points, as shown in the attached table, the voltage time test should be free of abnormalities.
6, mechanical properties
(1) Insertion force: The insertion force obtained by inserting the combined speed of 25 mm to ±3 mm/min shall conform to the specifications of the insertion force.
(2). Pull out force: pull out at a speed of 25 mm ± 3 mm / min. The pull-out force of the pull-out should be in accordance with the specifications of the pull-out force.
(3) Durability: The following requirements shall be met after the insertion of the 30 owing at the speed of (10 ow/minute) and then the test.
Answer: The contact impedance is within two digits of the initial value.
B: The pull-out force should meet the specification value.
(4). Terminal holding force: Pull the terminal out of the HSG at a speed of 5 mm ± 3 mm / min. The pulling force should meet the tensile force specification.
(5). PIN retention: The PIN is pushed out of BASE at a speed of 5 mm ± 3 mm / min, and the thrust should be in accordance with the thrust specification.
(6). Terminal riveting force: Pull the terminal out of the WIRE at a speed of 5 mm ± 3 mm / min. The pulling force should meet the riveting specification value.
7, environmental performance
(1) Temperature rise of the terminal: After applying the maximum rated current of AC to the thermal equilibrium for any joint, the temperature rise value should be 30 °C or less.
(2). Vibration resistance: In the energized state of DC 0.1A, the test is carried out under the conditions of amplitude 1.5m / m and frequency 10Hz-55Hz / Min, and the X, Y and Z axes are 3 times each time and 2 hours after each axis. The following requirements:
Answer: The contact impedance should be within two of the initial value;
B: discontinuous conduction time is below 1 microsecond;
C: The appearance should be free from abnormalities.
(3). Impact resistance: Under the condition of DC 0.1A, the test is carried out under the acceleration condition of 50g and the X, Y and Z axes are 3 times. After the test, the following requirements should be met. a: I discontinuous conduction time is 1 microsecond. Below, b: the appearance should be no abnormality.
(4). Tin-like property: immersed in a tin bath of 230±50°C for 3±1 seconds from the terminal of the terminal, and immersed in a tin bath of 230±50°C for more than 95%.
(5) High temperature resistance: after being placed in a temperature and temperature bath of 85±2 °C for 96 hours, it should be abnormal and the contact resistance should be within twice of the initial value.
(6) Solder heat resistance: from the terminal body of 1.2 mm at the reference surface, 5 ± 1 second in the tin bath with immersion self-esteem 260 ± 50 °C, the insulator should be free from abnormal state such as crack deformation, and the terminal strength should be within the specification. .
(7) Moisture resistance: 96-inch in a constant temperature and humidity chamber with a temperature of 85±2°C and a humidity of 90%~95%. The test within 30 minutes after wiping the droplets should meet the following requirements:
A. The contact impedance should be within the initial two digits;
B. The insulation resistance should be above 10MΩ;
C. The appearance should be free of irregularities;
D. Should meet the requirements of withstand voltage.
(8) Salt spray test: Place the sample at 35±2°C, and the ratio of 5±1% of salt spray, 16 hours ON, 8 hours OFF for one cycle, 3 cycles after washing with water, should meet the following Requirements, one: the contact impedance should be less than twice the initial value, C: no cracks or obvious corrosion.
(9) Vulcanization gas test: After the sample is placed at 40±2° C. and the vulcanization gas with a concentration of 50±5 ppm is used for 24 hours, the contact resistance should be within twice the initial value.
8, copper conductor related detection items
(1) Wire diameter tolerance:
When 0.10 mm ≦d ≦ 0.40 mm, the tolerance is ±0.004 mm;
0.40 mm
(2). Maximum outer diameter and minimum outer diameter difference (F)
When 0.10 mm ≦d ≦ 0.40 mm, the allowable difference ̊F<0.004 mm;
0.40 mm
(3) Elongation (soft state): the total length of the taken line is 20mm
0.10 mm ≦d ≦ 0.25 mm, elongation ≧ 12%; 0.25 mm
- Elongation = (breaking time -20) / 20
9, copper conductor related performance
The most commonly used conductor in wire and cable is copper, which has comprehensive properties such as high electrical and thermal conductivity, high ductility, good strength, and can be alloyed with other metals or coated with other metals. .
Copper conductors used at temperatures up to 300 °F (or 400 °F for a short time) are coated with tin, tin-lead or pure lead and have a coating thickness of 40 to 70 micro-inch. In addition to being used to minimize oxidation, these coatings also increase solderability and corrosion protection.
Copper wires that are used continuously (or at a short time of 500 °F) at temperatures up to 400 °F are plated with a minimum of 40 micro-inch silver, which is well exposed to higher temperatures. The silver plating layer is more conductive than the tin plating layer when the frequency is sufficiently high and the skin effect becomes high.
Copper or copper-clad steel conductors are used to increase strength, but the use of these materials is always at the expense of conductivity. For example, cadmium copper, a copper alloy containing 0.5-1.0% cadmium, has a tensile strength of 150% of copper, but the electrical conductivity is only about 80% of copper. In addition, the tensile strength of the copper-clad steel wire is 150-200% of copper, but the electrical conductivity is usually only 30-40% of copper.
Aluminum alloy is lighter than copper conductors of the same specification, but its electrical conductivity is only about 60% of copper. In addition, when exposed to air, aluminum forms a surface oxide that can form an undesirable high resistance connection. Therefore, the conductors in wire and cable are often made of copper. According to the current industry, there are roughly the following types of conductors: solid conductors, stranded conductors, and braided conductors.
A. Solid conductor - . The use of solid (single strand) conductors with little wire and cable deflection is advantageous in that it is less expensive than equivalent stranded wires and is usually used for wires and cables with solid conductors. Small instrument, backplane wiring or any similar mounting line for fixed equipment.
B. Stranded conductors - Stranded conductors are used in most wire and cable to provide better flexibility and longer flex life. From a practical point of view, stranded conductors have a longer life than solid conductors. . If there is a small V-shaped crack or similar damage, it will break as soon as it is bent a few times. However, in the same operation, only a few conductors of the stranded conductor are scored or damaged, and the remaining damaged strands still provide an appropriate service life.
C. Braided Conductors - - Flat or round (tubular) braided conductors are also sometimes used in certain applications where they are more suitable than round solid or stranded cables. The braided conductor is rarely insulated because the insulating layer prevents high deflection and the ability to slightly stretch the length due to the axial pushing and pulling of the cable.
10, wire and cable insulation
The insulation of wire and cable can be divided into two basic categories - thermoset and thermoplastic, but there are so many kinds of compounds, mixtures and mixtures in each category, so that the available insulation materials are almost unlimited. Most insulating materials consist of a compound made of a synthetic rubber polymer (thermosetting) and a compound made of a synthetic material to provide special physical and electrical properties.
(1) Thermosetting insulating materials:
Thermoset materials are characterized by mechanical stresses that can be stretched, compressed, or otherwise deformed (within reasonable limits), and when this mechanical stress is removed, can "bounce back" to the original state and shape. Since thermoset insulating materials are not susceptible to thermal softening, they do not melt, flow or deform during the added thermal and electrical overloads, which cause internal heating.
(2). Thermoplastic insulation
Thermoplastic insulation is known for its excellent electrical properties and low cost. Thermoplastics are widely used as insulating materials due to their good electrical properties due to their very thin insulation thickness, especially in high voltage cables. In addition, a cable having a thin insulating layer is generally smaller in size than a cable made of a thermosetting insulating material having the same electrical properties.
Several modified thermoplastic insulating materials can be formulated with a variety of basic thermoplastic materials. Sometimes the main change is color, but most thermoplastics have different grades to meet specific temperature, strength and environmental resistance requirements. Naturally, these materials are thermoformed, thermally softened and flowed under mechanical pressure, and then retained in their deformed shape and state after cooling and/or removal of mechanical strain.
Polyvinyl chloride insulation is widely used in wire and cable because of its high dielectric strength and mechanical strength, high flexibility and flame retardancy, water resistance, oil resistance and wear resistance. They also have low cost and convenience.
评论
发表评论