CN112038028A - Method for manufacturing high-reliability low-resistance thermistor - Google Patents
Method for manufacturing high-reliability low-resistance thermistor Download PDFInfo
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- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
- H01C7/027—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
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Abstract
The invention belongs to the technical field of resistors, and particularly relates to a manufacturing method of a high-reliability low-resistance thermistor, which at least comprises the following steps: firstly, mixing a polymer and a conductive substance together in a double-screw granulator by adopting a double-screw granulation processing mode and granulating to form a mixture; secondly, melting and extruding the mixture obtained in the first step by adopting a single-screw extrusion processing technology in a single-screw extrusion molding machine to form a PPTC sheet material, and forming the sheet material between an upper electrode copper foil and a lower electrode copper foil to form a PPTC chip; thirdly, performing electron beam irradiation treatment on the PPTC chip formed in the second step; and fourthly, stamping the PPTC chip, and then forming the self-recovery fuse by assembling or through a PCB processing technology. In the prior art, the low-resistance thermistor with good resistance distribution uniformity and lower resistance characteristic can be obtained by optimizing the manufacturing process of the low-resistance thermistor.
Description
Technical Field
The invention belongs to the technical field of resistors, and particularly relates to a manufacturing method of a high-reliability low-resistance thermistor.
Background
The self-recovery fuse is made of a Positive Temperature Coefficient (Polymer Positive Temperature Coefficient) Polymer composite material (PPTC) with a Positive Temperature Coefficient effect, the Positive Temperature Coefficient effect means that the resistivity of the material per se is increased along with the increase of the Temperature within a certain Temperature range, and when the Temperature is increased, the resistance value of the material is gradually changed from a low resistance state to a high resistance state to reach and be stabilized in the high resistance state, so that the current value of a loop is reduced; when the circuit or the temperature returns to normal, the resistance value returns to the low resistance state from the high resistance state and can be used normally, and the self-recovery characteristic is realized. The polymer positive temperature coefficient self-recovery fuse has the characteristic that the resistance is sensitive to the temperature change, can be used as a material for sensing current or temperature, is widely applied to over-current or over-temperature protection circuits, and relates to the fields of automobile application, industrial control application, household appliance application, computer portable equipment application, mobile phone Bluetooth and other consumer electronics.
The low-resistance PPTC thermistor is widely applied to the fields of mobile phone battery protection, quick charging data line Type C port protection, USB 3.0 port protection, automobile adapter port protection, Bluetooth headset safety protection and the like, and due to the miniaturization and light weight of the products, the actual application power requirement is higher and higher, namely the voltage and current levels are higher and higher, so that the low-resistance PPTC thermistor is required to be lower and lower in resistance value, high in resistance value stability, good in heat resistance and weather resistance and high in ageing resistance.
The general processing flow of the self-recovery fuse in the prior art is as follows: firstly, polymer and a conductive object are processed in an open mill mode or in a mixing mode to form a compound, then the compound is pressed to form a PPTC (polymer PTC) chip, and finally the PPTC chip is punched and cut or processed into the self-recovery fuse through a PCB. The procedure is relatively simple, but the consistency is poor. The Polymer PTC (PPTC) material is compounded and processed by one or more conductive particles, one or more crystalline or semi-crystalline polymer materials and various additives, and the existing compound processing mode mainly selects open mill type processing or mixing processing, and then is crushed into particles or granulated; this mill processing mode is open, needs the artifical incessant packing of manual work to mix, and it is inhomogeneous to have the packing, and the material inside and the pollution risk are wrapped up in to the moisture. Non-uniform packing can lead to poor resistivity uniformity and unstable performance. The mixing processing mode is mixing in a closed chamber, but has the defects of inaccurate internal temperature control and poor mixing uniformity, and finally causes uneven distribution of the resistance value of the material.
In the process of pressing and processing the composite into the PPTC chip, electrode copper foils are covered on the upper surface and the lower surface of the PPTC composite material which is processed through compounding through a press; when in pressing, a special buffer material, namely Teflon demoulding cloth is needed, and the special buffer material and the steel plate form a multilayer structure. The process has the problems of poor thickness consistency and poor mixing uniformity of the composite material, so that the resistance distribution is not uniform enough. The reason for poor thickness consistency is that the multi-layer structure is formed by laminating and pressing a buffer material, Teflon demoulding cloth and a steel plate, and the defects of multiple positioning of lamination, large accumulated tolerance, uneven pressure and the like exist. The defects of the two processes cause the resistance value of the polymer self-recovery fuse (PPTC) to be uneven and the performance to be unstable.
Aiming at the defects of the prior art, the application aims to provide a manufacturing method of a high-reliability low-resistance thermistor so as to improve the resistance consistency and performance stability of a product.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the manufacturing method of the high-reliability low-resistance thermistor is provided to improve the resistance consistency and performance stability of the product.
In order to achieve the purpose, the invention adopts the following technical scheme:
a manufacturing method of a high-reliability low-resistance thermistor at least comprises the following steps:
firstly, mixing a polymer and a conductive substance together in a double-screw granulator by adopting a double-screw granulation processing mode and granulating to form a mixture;
secondly, melting and extruding the mixture obtained in the first step by adopting a single-screw extrusion processing technology in a single-screw extrusion molding machine to form a PPTC sheet material, and forming the sheet material between an upper electrode copper foil and a lower electrode copper foil to form a PPTC chip;
thirdly, performing electron beam irradiation treatment on the PPTC chip formed in the second step;
and fourthly, stamping the PPTC chip, and then forming the low-resistance thermistor through assembly or a PCB processing technology. After the PPTC chip is manufactured, the shape requirement of the self-recovery safety thermistor can be met.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, in the first step, the mass ratio of the polymer to the conductive substance is (2-10): (90-98). The proportion of the conductive substance is more than 3 times of the proportion of the polymer powder by volume.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, in the first step, the polymer is at least one of polyethylene, polyvinyl chloride, chlorinated polyethylene butadiene-acrylonitrile copolymer, polytetrafluoroethylene, polycarbonate, polyvinyl fluoride, maleic anhydride grafted polyethylene and polypropylene; the conductive substance is at least one of titanium carbide, vanadium carbide, zirconium carbide, tungsten carbide, niobium carbide, molybdenum carbide, titanium boride, vanadium boride, zirconium boride, niobium boride and titanium nitride.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, the particle size of the conductive substance is between 0.01 and 20 microns.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, the specific process of the twin-screw granulation processing in the first step is as follows: the polymer and the conductive substance are premixed and then added into the self-temperature-control heating material cylinder from the feeding port, the polymer and the conductive substance are uniformly mixed by the double screws and then extruded out of the discharging die head to form a mixture, and moisture is discharged through an exhaust hole and a vacuumizing hole which are formed in the self-temperature-control heating material cylinder in the mixing process.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, eight self-temperature-control heating material cylinders are arranged, wherein the temperature in a first self-temperature-control heating material cylinder farthest from a discharge die head is 110-130 ℃, the temperature from a second self-temperature-control heating material cylinder to an eighth self-temperature-control heating material cylinder is 220-270 ℃, and the temperature of the discharge die head is 220-270 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the rotating speed of the double screws is 8-15 rpm. Because the density fall of the material is large, if the material is processed by adopting an early open mixing type or mixing type, the material is not well mixed, so that the resistance consistency of the material is poor, and the material is easy to wrap moisture or impurities to pollute the risk; the invention mixes the polymer and the conductive material uniformly, the gas is discharged through the vacuum-pumping port during the extrusion process, the moisture in the material can be discharged through the vent hole and the vacuum-pumping port during the processing process, the polymer material is ensured to have no moisture, the degree of automation is high, the discharging is stable, the mixing is uniform, and the material performance is stable.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, in the second step, the specific process of melt extrusion is as follows: adding the mixture obtained in the first step into a self-temperature-control heating high-wear-resistance material cylinder from a feeding area, heating the mixture by a high-wear-resistance single screw rod, and extruding the mixture from a forming die head to form a PPTC sheet material, wherein moisture is discharged through an exhaust hole and a vacuum exhaust port which are arranged on the self-temperature-control heating high-wear-resistance material cylinder in the mixing process;
the specific process for forming the sheet material between the upper electrode copper foil and the lower electrode copper foil comprises the following steps: and automatically laminating an upper electrode copper foil and a lower electrode copper foil on the upper surface and the lower surface of the PPTC sheet material respectively through an upper roller and a lower roller so as to form the PPTC chip.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, eight material cylinders with self-temperature-control heating and high wear resistance are provided, wherein the temperature in the first material cylinder with self-temperature-control heating and high wear resistance farthest from the forming die head is 110-130 ℃, the temperature from the second material cylinder with self-temperature-control heating and high wear resistance to the eighth material cylinder with self-temperature-control heating and high wear resistance is 235-275 ℃, and the temperature of the forming die head is 235-275 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 180-220 ℃; the rotating speed of the roller is set to be between 2 and 5 scales. And gas is included or released in the extrusion process and is discharged through the vacuumizing port, so that the polymer composite material is ensured to have no water vapor. The process has high automation degree, a vacuumizing function, moisture removal, high roller precision and capability of ensuring the thickness consistency of the rolled PPTC chip.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, the thickness of the PPTC chip is 0.18-2.5 mm, the width of the PPTC chip is 200-300 mm, and the length of the PPTC chip is 300-500 mm.
As an improvement of the manufacturing method of the high-reliability low-resistance thermistor, the invention integrates the requirements of material density, material thickness, electron beam energy and irradiation dose, and the specific parameters in the electron beam irradiation treatment of the third step are defined as follows: the lamination is controlled to be 1-3 layers, the energy of an electron beam is 2-10 Mev, the electron beam current is selected to be 5-20 mA, the speed of a trolley is controlled to be 4-20 m/min, and the irradiation dose is 30-150 kGy (which can be realized by multiple times of irradiation). In the invention, according to the volume ratio, the conductive substance accounts for more than 3 times of the polymer powder; the density drop between the conductive substance and the polymer is large, and the conductive substance is easy to settle or overflow in the polymer due to gravity factor in the molten or expanded state of the high polymer material, so that the PTC positive temperature effect is weakened; the cross-linking property of the internal high molecular structure of the PPTC chip which is not subjected to electronic irradiation is unstable, so that the heat resistance and the aging resistance of the PPTC composite material are poor, the resistance change is unstable after a long time, the resistance change rate is high, the PPTC effect is poor, and the service life of the PPTC is greatly shortened; therefore, the PPTC chip can enhance the cross-linking of the macromolecular structure by carrying out electron irradiation, enhance the positive temperature effect of the PPTC, enhance the heat resistance and the ageing resistance, and ensure the service life and the safety of the PPTC. By reasonably controlling the lamination quantity, the electron beam energy control, the electron beam flow control and the irradiation trolley speed, the uniformity of the irradiation absorbed dose of the PPTC chip is finally achieved, and the heat resistance and the ageing resistance of the PPTC chip are improved.
In the prior art, the low-resistance thermistor with good resistance distribution uniformity and lower resistance characteristic can be obtained by optimizing the manufacturing process of the low-resistance thermistor.
Drawings
FIG. 1 is a process flow diagram of the present invention.
FIG. 2 is a schematic view of the structure of a twin-screw pelletizer used in the first step of the present invention.
FIG. 3 is a schematic view showing the structure of the apparatus used in the second step of the present invention.
Detailed Description
Example 1
As shown in fig. 1, the method for manufacturing a high-reliability low-resistance thermistor provided in this embodiment at least includes the following steps:
firstly, mixing a polymer and a conductive substance together in a double-screw granulator by adopting a double-screw granulation processing mode and granulating to form a mixture;
secondly, melting and extruding the mixture obtained in the first step by adopting a single-screw extrusion processing technology in a single-screw extrusion molding machine to form a PPTC sheet material, and forming the sheet material between an upper electrode copper foil and a lower electrode copper foil to form a PPTC chip;
thirdly, performing electron beam irradiation treatment on the PPTC chip formed in the second step;
and fourthly, stamping the PPTC chip, and then forming the low-resistance thermistor through assembly or a PCB processing technology.
In the first step, the mass ratio of the polymer to the conductive substance is 7: 93, the polymer is polyethylene, the conductive substance is titanium carbide, and the particle size of the conductive substance is between 0.01 and 20 μm.
The structure of the twin-screw granulator used in the first step is shown in fig. 2, and comprises a main motor 1, 8 self-temperature-control heating material cylinders 2 which are combined into a gun barrel, wherein equidirectional twin screws are arranged in the gun barrel and connected with the main motor 1, the first material cylinder 2 is connected with the main motor 1, the second material cylinder 2 is provided with a feeding opening 3, the fourth material cylinder 2 is provided with an exhaust hole 4, the seventh material cylinder 2 is provided with a vacuum pumping opening 5, and the eighth material cylinder 2 is connected with a discharge die head 6.
The specific process of the twin-screw granulation processing in the first step comprises the following steps: after the polymer and the conductive substance are premixed, the polymer and the conductive substance are added into a second self-temperature-control heating material cylinder 2 from a feeding port 3, after the temperature of each temperature zone reaches, a main motor is started, the polymer and the conductive substance are uniformly mixed by double screws and then are extruded from a discharging die head 6 and granulated (a cutter is arranged on the discharging die head 6 and is cut into particles), a mixture is formed, and in the mixing process, moisture is discharged through an exhaust hole 4 and a vacuumizing port 5 which are arranged on the self-temperature-control heating material cylinder 2.
The temperature in the first self-temperature-control heating material cylinder 2 farthest from the discharging die head 6 is 120 ℃, the temperature from the second self-temperature-control heating material cylinder 2 to the eighth self-temperature-control heating material cylinder 2 is 250 ℃, and the temperature of the discharging die head 6 is 250 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the twin screw was rotated at 10 rpm.
The equipment used in the second step is shown in fig. 3, and comprises a main motor 7 and 8 self-temperature-control heating high-wear-resistance material cylinders 8, wherein the first cylinder 8 is connected with the main motor 7, the second cylinder 8 is provided with a feeding area 14, the fourth cylinder 8 is provided with an exhaust hole 10, the seventh cylinder 8 is provided with a vacuum exhaust port 11, a high-wear-resistance single screw rod is arranged in the cylinder 8 and connected with the main motor 7, the eighth cylinder 8 is connected with a forming die head 9, and one side of the forming die head 9 is provided with an upper roller 12 and a lower roller 13;
in the second step, the melt extrusion process comprises the following specific steps: adding the mixture obtained in the first step into a self-temperature-control heating high-wear-resistance material cylinder 8 from a feeding area, starting a main motor 7 when the temperature of each temperature area is raised to a set temperature range, starting feeding and extruding, heating the mixture by a high-wear-resistance single screw rod, and extruding the mixture from a forming die head 9 to form a PPTC sheet material, wherein in the mixing process, moisture is discharged through an exhaust hole 10 and a vacuum exhaust hole 11 which are arranged on the self-temperature-control heating high-wear-resistance material cylinder 8;
the specific process for forming the sheet material 17 between the upper electrode copper foil 15 and the lower electrode copper foil 16 is as follows: an upper electrode copper foil 15 and a lower electrode copper foil 16 are respectively and automatically coated on the upper surface and the lower surface of a PPTC sheet material 17 through an upper roller 12 and a lower roller 13, so that a PPTC chip is formed.
The temperature in the first self-temperature-control heating high-wear-resistance material cylinder 8 farthest from the molding die head 9 is 120 ℃, the temperature from the second self-temperature-control heating high-wear-resistance material cylinder 8 to the eighth self-temperature-control heating high-wear-resistance material cylinder 8 is 270 ℃, and the temperature of the molding die head is 270 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 200 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.265 mm.
The specific parameters in the electron beam irradiation treatment in the third step are as follows: the lamination is controlled to be 1-3 layers, the energy of an electron beam is 2-10 Mev, the electron beam current is selected to be 5-20 mA, the speed of a trolley is controlled to be 4-20 m/min, and the irradiation dose is 30-150 kGy.
Processing the PPTC chip obtained in the third step into a chip low-resistance thermistor (self-recovery fuse) with the chip size of 3.05mm, the width of 1.62mm and the thickness of 0.265mm by a PCB (printed circuit board); the resistance and thickness of the low-resistance thermistor of the patch were measured, and the resistivity uniformity was calculated, the results are shown in table 1.
Example 2
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 4: 96. the polymer is polyvinyl chloride, the conductive substance is vanadium carbide, and in the first-step double-screw granulation process, the temperature in a first self-temperature-control heating material cylinder farthest from a discharge die head is 115 ℃, the temperature from a second self-temperature-control heating material cylinder to an eighth self-temperature-control heating material cylinder is 240 ℃, and the temperature of the discharge die head is 240 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the twin screw was rotated at 12 rpm. In the second step, in the specific process of melt extrusion, the temperature in the first self-temperature-control heating high-wear-resistance material barrel farthest from the forming die head is 115 ℃, the temperature from the second self-temperature-control heating high-wear-resistance material barrel to the eighth self-temperature-control heating high-wear-resistance material barrel is 260 ℃, and the temperature of the forming die head is 260 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 190 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.271 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.271mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 5: 95. in the specific process of the first-step double-screw granulation processing, the temperature in a first self-temperature-control heating material cylinder farthest from a discharge die head is 125 ℃, the temperature from a second self-temperature-control heating material cylinder to an eighth self-temperature-control heating material cylinder is 260 ℃, and the temperature of the discharge die head is 260 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the twin screw was rotated at 11 rpm. In the second step, in the specific process of melt extrusion, the temperature in the first self-temperature-control heating high-wear-resistance material cylinder farthest from the forming die head is 125 ℃, the temperature from the second self-temperature-control heating high-wear-resistance material cylinder to the eighth self-temperature-control heating high-wear-resistance material cylinder is 270 ℃, and the temperature of the forming die head is 270 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 195 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.264 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.264mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 3: 97. in the specific process of the first-step double-screw granulation processing, the temperature in a first self-temperature-control heating material cylinder farthest from a discharge die head is 125 ℃, the temperature from a second self-temperature-control heating material cylinder to an eighth self-temperature-control heating material cylinder is 255 ℃, and the temperature of the discharge die head is 255 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the twin screw was rotated at 9 rpm. In the second step, in the specific process of melt extrusion, the temperature in the first self-temperature-control heating high-wear-resistance material barrel farthest from the forming die head is 125 ℃, the temperature from the second self-temperature-control heating high-wear-resistance material barrel to the eighth self-temperature-control heating high-wear-resistance material barrel is 265 ℃, and the temperature of the forming die head is 265 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 205 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.264 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.268mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 6: 94. the polymer is polycarbonate, the conductive substance is niobium carbide, and the temperature of the upper roller and the lower roller is 200 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.273 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.273mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 8: 92. the polymer is polyvinyl fluoride, the conductive substance is molybdenum carbide, and the temperature of the upper roller and the lower roller is 200 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.261 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.261mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 7
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 9: 91. the polymer is maleic anhydride grafted polyethylene, the conductive substance is titanium boride, and the temperature of the upper roller and the lower roller is 200 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.269 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.269mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Example 8
Unlike example 1, in the first step, the mass ratio of the polymer to the conductive substance was 10: 90. the polymer is polypropylene, the conductive substance is titanium nitride, and the temperature of the upper roller and the lower roller is 200 ℃; the rotating speed of the roller is set to be 2-5 scales so as to form a PPTC chip with the thickness of 0.270 mm.
And processing the PPTC chip obtained in the third step into a patch low-resistance thermistor with the chip size of 3.05mm in length, 1.62mm in width and 0.269mm in thickness through a PCB.
The rest is the same as embodiment 1, and the description is omitted here.
Examples 9 to 18
Different from embodiment 1, the thicknesses of the low-resistance thermistor of the patch are 0.271mm, 0.264mm, 0.268mm, 0.273mm, 0.261mm, 0.269mm, 0.258mm, 0.262mm and 0.265mm in sequence, and the rest is the same as embodiment 1 and is not repeated herein.
Comparative example 1
The preparation method adopts the prior preparation process: firstly, polyethylene and titanium carbide are mixed according to the weight ratio of 7: 93, the particle size of the titanium carbide is between 0.01 and 20 microns, then the compound is pressed to form a PPTC (polymer PTC) chip, and finally the PPTC chip is punched and processed into a patch low-resistance thermistor with the chip size of 3.05mm, the width of 1.62mm and the thickness of 0.265mm through a PCB (printed Circuit Board). The resistance (self-recovery fuse) of the low-resistance thermistor of the chip was measured for thickness, and the resistivity uniformity was calculated, and the results are shown in table 1.
Comparative examples 2 to 10
Unlike comparative example 1, the low-resistance thermistor of the patch has thicknesses of 0.260, 0.245, 0.251, 0.263, 0.285, 0.235, 0.266, 0.243, and 0.259 in this order, and the rest is the same as example 1 and will not be described again. The resistance and thickness of the low-resistance thermistor of the patch were measured, and the resistivity uniformity was calculated, the results are shown in table 1.
Table 1: test results of examples 1, 9 to 18 and comparative examples 1 to 10.
As can be seen from table 1, the low-resistance thermistor of the chip manufactured by the manufacturing method of the present invention has good resistance distribution uniformity and can achieve lower resistance characteristics.
Appropriate changes and modifications to the embodiments described above will become apparent to those skilled in the art from the disclosure and teachings of the foregoing description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (10)
1. A manufacturing method of a high-reliability low-resistance thermistor is characterized by at least comprising the following steps:
firstly, mixing a polymer and a conductive substance together in a double-screw granulator by adopting a double-screw granulation processing mode and granulating to form a mixture;
secondly, melting and extruding the mixture obtained in the first step by adopting a single-screw extrusion processing technology in a single-screw extrusion molding machine to form a PPTC sheet material, and forming the sheet material between an upper electrode copper foil and a lower electrode copper foil to form a PPTC chip;
thirdly, performing electron beam irradiation treatment on the PPTC chip formed in the second step;
and fourthly, stamping the PPTC chip, and then forming the low-resistance thermistor through assembly or a PCB processing technology.
2. The method for manufacturing a high-reliability low-resistance thermistor according to claim 1, wherein: in the first step, the mass ratio of the polymer to the conductive substance is (2-10): (90-98).
3. The method for manufacturing a high-reliability low-resistance thermistor according to claim 1, wherein: in the first step, the polymer is at least one of polyethylene, polyvinyl chloride, chlorinated polyethylene butadiene-acrylonitrile copolymer, polytetrafluoroethylene, polycarbonate, polyvinyl fluoride, maleic anhydride grafted polyethylene and polypropylene; the conductive substance is at least one of titanium carbide, vanadium carbide, zirconium carbide, tungsten carbide, niobium carbide, molybdenum carbide, titanium boride, vanadium boride, zirconium boride, niobium boride and titanium nitride.
4. The method for manufacturing a high-reliability low-resistance thermistor according to claim 1, wherein: the particle size of the conductive substance is between 0.01 and 20 μm.
5. The method for manufacturing a high-reliability low-resistance thermistor according to claim 1, wherein: the specific process of the twin-screw granulation processing in the first step comprises the following steps: the polymer and the conductive substance are premixed and then added into the self-temperature-control heating material cylinder from the feeding port, the polymer and the conductive substance are uniformly mixed by the double screws and then extruded out of the discharging die head to form a mixture, and moisture is discharged through an exhaust hole and a vacuumizing hole which are formed in the self-temperature-control heating material cylinder in the mixing process.
6. The method for manufacturing a high-reliability low-resistance thermistor according to claim 5, wherein: the number of the self-temperature-control heating material cylinders is eight, wherein the temperature in the first self-temperature-control heating material cylinder farthest from the discharge die head is 110-130 ℃, the temperature from the second self-temperature-control heating material cylinder to the eighth self-temperature-control heating material cylinder is 220-270 ℃, and the temperature of the discharge die head is 220-270 ℃; the vacuum degree of the vacuumizing port is less than 500 Psi; the rotating speed of the double screws is 8-15 rpm.
7. The method for manufacturing a high-reliability low-resistance thermistor according to claim 5 or 6, wherein: in the second step, the melt extrusion process comprises the following specific steps: adding the mixture obtained in the first step into a self-temperature-control heating high-wear-resistance material cylinder from a feeding area, heating the mixture by a high-wear-resistance single screw rod, and extruding the mixture from a forming die head to form a PPTC sheet material, wherein moisture is discharged through an exhaust hole and a vacuum exhaust port which are arranged on the self-temperature-control heating high-wear-resistance material cylinder in the mixing process;
the specific process for forming the sheet material between the upper electrode copper foil and the lower electrode copper foil comprises the following steps: and automatically laminating an upper electrode copper foil and a lower electrode copper foil on the upper surface and the lower surface of the PPTC sheet material respectively through an upper roller and a lower roller so as to form the PPTC chip.
8. The method for manufacturing a high-reliability low-resistance thermistor according to claim 7, wherein: the number of the material barrels for self-temperature-control heating high-wear-resistance materials is eight, wherein the temperature in the first material barrel for self-temperature-control heating high-wear-resistance materials farthest away from the forming die head is 110-130 ℃, the temperature from the second material barrel for self-temperature-control heating high-wear-resistance materials to the eighth material barrel for self-temperature-control heating high-wear-resistance materials is 235-275 ℃, and the temperature of the forming die head is 235-275 ℃; the vacuum degree of the vacuum exhaust port is less than 500 Psi; the temperature of the upper roller and the lower roller is 180-220 ℃; the rotating speed of the roller is set to be between 2 and 5 scales.
9. The method for manufacturing a high-reliability low-resistance thermistor according to claim 7, wherein: the thickness of the PPTC chip is 0.18-2.5 mm, the width is 200-300 mm, and the length is 300-500 mm.
10. The method for manufacturing a high-reliability low-resistance thermistor according to claim 1, wherein: the specific parameters in the electron beam irradiation treatment in the third step are as follows: the lamination is controlled to be 1-3 layers, the energy of an electron beam is 2-10 Mev, the electron beam current is selected to be 5-20 mA, the speed of a trolley is controlled to be 4-20 m/min, and the irradiation dose is 30-150 kGy.
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| CN114230894A (en) * | 2021-12-20 | 2022-03-25 | 东莞市贝特电子科技股份有限公司 | Manufacturing method for improving voltage resistance of PPTC product with ultralow resistance |
| CN115124277A (en) * | 2022-05-30 | 2022-09-30 | 北京科技大学 | Preparation method of organic-inorganic composite vanadium-oxygen compound electronic phase change material |
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