PPTC (Polymeric Positive Temperature Coefficient) surface-mounted device with series structure as well as preparation method and application thereof

Abstract

The invention discloses a PPTC surface-mounted device with a series structure and a preparation method and application thereof, and relates to the technical field of PP TC devices, the device comprises a metal series layer, a PPTC composite material layer and a metal electrode layer, the metal series layer is a top layer, the PPTC composite material layer is a middle layer, and the metal electrode layer is a bottom layer; the number of the metal electrode layers is two, the two metal electrode layers are horizontally distributed, and a gap is formed between the two metal electrode layers and is a blocking groove. And the PPTC composite material layer is prepared by printing PPTC ink. Compared with a traditional PPTC surface-mounted device, the PP TC surface-mounted device of the series structure can provide a longer conduction path under the same size, the voltage resistance is effectively improved, meanwhile, the preparation technology is remarkably simplified, and a feasible scheme is provided for efficiently preparing the ultra-small PPTC surface-mounted device with the high voltage resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of PPTC devices, and particularly to a PPTC surface-mount device with a series structure, a preparation method thereof, and an application thereof. Background Art

[0002] PPTC (polymer-based positive temperature coefficient) surface-mount devices have the advantages of high sensitivity and fast response, and their resistivity shows non-linear variation with the change of temperature. When a PPTC device is surface-mounted in a circuit, when the circuit generates a large current or the temperature is too high, the temperature of the PPTC device rises, its resistance value instantaneously increases, and the current in the circuit is cut off, thus playing a role in protecting the circuit; subsequently, as the temperature decreases, its resistance value can recover to the normal value, and the circuit operates normally, having a self-recovery characteristic.

[0003] In modern electronic devices and circuit designs, overcurrent protection is an important link to ensure the safety and reliability of the system. PPTC surface-mount devices, as overcurrent protection components, have been widely used in fields such as consumer electronics, automobiles, aerospace, etc. With the miniaturization and high integration of electronic products, higher performance requirements are put forward for PPTC surface-mount devices. Materials Science and Engineering (Vol. 198, pp. 78 - 81, 2014) reported a method for preparing PPTC circuit protection devices, which can effectively improve the current-carrying and voltage-withstanding capabilities and fast response capabilities of the devices, but the volume of this PPTC device is relatively large, and the improvement of the voltage-withstanding performance is limited, making it difficult to meet the requirements of current electronic devices. Therefore, how to achieve the miniaturization and mass production of PPTC surface-mount devices while improving the voltage-withstanding performance of PPTC surface-mount devices is a key problem that needs to be solved by those skilled in the art.

[0004] In view of this, the present application is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a PPTC surface-mount device with a series structure, a preparation method thereof, and an application thereof, so as to solve the problems mentioned in the above background art.

[0006] To solve the above technical problems, a PPTC surface-mount device with a series structure provided by the present invention includes a three-layer structure of a metal series layer, a PPTC composite material layer, and a metal electrode layer, wherein the metal series layer is the top layer, the PPTC composite material layer is the middle layer, and the metal electrode layer is the bottom layer; the metal electrode layer includes two pieces, the two metal electrode layers are horizontally distributed and there is a gap in the middle, and the gap is a blocking groove.

[0007] Further, the PPTC composite layer is prepared by printing with PPTC ink; the metal series connection layer and the metal electrode layer are one of copper foil, silver foil, aluminum foil, nickel foil, nickel-plated copper foil, and tin-plated copper foil.

[0008] Further, the PPTC ink is prepared by ball milling and mixing 1-5 parts of a polymer matrix, 2-20 parts of a conductive filler, and 5-20 parts of a solvent uniformly.

[0009] Further, the polymer matrix includes one or more mixtures of polyethylene and its copolymers, polypropylene and its copolymers, polyvinylidene fluoride and its copolymers, polycarbonate and its copolymers, polyethylene terephthalate and its copolymers, and polyamide and its copolymers; the conductive filler includes one or more mixtures of silver nanowires, carbon black, acetylene black, short carbon fibers, long carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphite, titanium carbide, tungsten carbide, tantalum carbide, titanium nitride, titanium diboride, aluminum nitride, magnesium nitride, and boron nitride; the solvent is one or more mixtures selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, diphenylamine, toluene, xylene, diethylene glycol ethyl ether, m-cresol, and phenol.

[0010] A preparation method of a PPTC surface mount device with a series connection structure includes the following steps:

[0011] S1: Printing the PPTC ink on the metal series connection layer by screen printing or knife coating and drying to obtain a metal series connection layer coated with a PPTC composite layer; S2: Printing the PPTC ink on the metal electrode layer by screen printing or knife coating and drying to obtain a metal electrode layer coated with a PPTC composite layer; S3: Thermally pressing two metal series connection layers and metal electrode layers coated with a PPTC composite layer to obtain a core material with a PPTC composite layer in the middle and a metal series connection layer and a metal electrode layer on the upper and lower layers respectively; S4: Bonding the metal series connection layer of the core material in S3 to the surface of silicone rubber; S5: Performing scribing on the surface of the metal electrode layer to scribe the core material into single-piece PPTC surface mount devices, and at the same time scribing out blocking grooves: S51: Scribing along the first scribing path to obtain a single strip of core material; S52: Scribing out the blocking grooves along the second scribing path; S53: Scribing along the third scribing path to obtain the PPTC surface mount device.

[0012] Further, the width of the PPTC surface mount device with a series connection structure is d, the length is D, and the width of the blocking groove is 0.1-0.3 times that of D.

[0013] Further, the drying temperature of the PPTC ink is 70-95 °C; the temperature of the thermal pressing is 150-200 °C.

[0014] Further, the interval of the first scoring track is D, the second scoring track is centered between two adjacent first scoring tracks, and the interval of the third scoring track is d and is perpendicular to the first scoring track.

[0015] Further, the first cutting track and the third scoring track should cut through the three-layer structures of the top layer, the middle layer and the bottom layer, and the second scoring track should cut through the bottom electrode layer without damaging the PPTC composite material layer.

[0016] An application of a PPTC surface mount device with a series structure in the field of overcurrent and overheat protection, connecting the PPTC surface mount device with the series structure to a circuit to play a circuit protection function.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The present invention discloses a PPTC surface mount device with a series structure. Compared with the traditional PPTC surface mount device, it can provide a longer conduction path under the same size, effectively improving the withstand voltage performance. At the same time, the manufacturing process is significantly simplified, providing a feasible solution for the efficient manufacture of ultra-small PPTC surface mount devices with high withstand voltage performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a PPTC surface mount device with a series structure;

[0020] Figure 2 It is a flowchart of a manufacturing method of a PPTC surface mount device with a series structure;

[0021] Figure 3 It is a schematic diagram of scoring tracks in a PPTC surface mount device with a series structure, its manufacturing method and application.

[0022] In the figure: A, metal series layer; B, PPTC composite material layer; C, metal electrode layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0024] Please refer to Figures 1-3 , the present invention provides a technical solution: a PPTC surface mount device with a series structure, its manufacturing method and application, optimizing the structural design and manufacturing process of the PPTC surface mount device, and at the same time improving the withstand voltage performance of the PPTC surface mount device.

[0025] Example 1

[0026] (1) Polyethylene, silver nanowires and N,N-dimethylformamide were fully dissolved and mixed evenly according to a mass ratio of 1:2:5 to obtain PPTC ink. Then it was scrape-coated on a 60-μm-thick nickel-plated copper foil and placed in a vacuum drying oven at 75 °C to completely volatilize the solvent, obtaining a metal electrode layer and a metal series layer covered with a PPTC composite material layer about 180 μm thick.

[0027] (2) The metal electrode layer and the metal series layer covered with the PPTC composite material layer were bonded to each other and put into a hot press for hot pressing. The hot pressing temperature was 200 °C and the hot pressing pressure was 3 MPa, obtaining a core material with a PPTC composite material layer in the middle and a metal series layer and a metal electrode layer on the upper and lower layers respectively.

[0028] (3) The metal series layer of the core material obtained by hot pressing was bonded to the surface of the viscous silicone rubber, and then put into a slitting lathe for slitting. Slitting was carried out on the surface of the metal electrode layer. First, it was slit along the first slitting track to obtain a single core material. The spacing of the first slitting tracks was 1.20 mm and the slitting depth was 0.30 mm. Then, a blocking groove was slit along the second slitting track. The second slitting track was parallel and centered between two adjacent first slitting tracks. The slitting depth was 0.06 mm and the width of the blocking groove was 0.30 mm. Finally, it was slit along the third slitting track with a spacing of 0.60 mm and perpendicular to the first slitting track to obtain a PPTC surface mount device with a series structure, as Figure 3 shown.

[0029] Comparative Example 1

[0030] The preparation of a traditional PPTC surface mount device, and the preparation steps are as follows:

[0031] (1) The PPTC thin film was prepared by the melting method. 5 g of polyethylene and 10 g of silver nanowires were put into an extruder, and after being melted and mixed at high temperature, they were extruded and formed into a PPTC composite material thin film.

[0032] (2) According to the order of the nickel-plated copper foil layer, the PPTC composite material layer and the nickel-plated copper foil layer, a conductive composite material core layer with a positive temperature coefficient effect was obtained by hot pressing process.

[0033] (3) Drilling was carried out on the surface of the conductive composite material core layer for positioning purposes.

[0034] (4) The conductive composite material core layer was placed in a circuit grinding machine to mark the inner layer circuit with a chemical solution, and then put into a film laminating machine to paste a photosensitive film and carry out exposure.

[0035] (5) The inner layer circuit was etched with a corrosive chemical solution in an etching machine.

[0036] (6) Use a screen printing machine to print solder mask ink on the upper and lower surfaces of the conductive composite material core layer with the inner layer circuit etched, and cure it at 150 °C for 1 h.

[0037] (7) Die cut into PPTC mounting devices with dimensions of 1.20 mm * 0.60 mm.

[0038] Example 2

[0039] (1) Dissolve polyamide, titanium carbide, and anhydrous formic acid in a mass ratio of 1:14:5 and mix them evenly to obtain PPTC ink. Then scrape it onto a 60-μm-thick aluminum foil and place it in a vacuum drying oven at 70 °C to completely volatilize the solvent, obtaining a metal electrode layer and a metal series layer covered with a PPTC composite material layer about 200 μm thick.

[0040] (2) Bond the metal electrode layer and the metal series layer covered with the PPTC composite material layer together and put them into a hot press for hot pressing. The hot pressing temperature is 200 °C and the hot pressing pressure is 6 MPa, obtaining a core material with a PPTC composite material layer in the middle, and a metal series layer and a metal electrode layer on the upper and lower layers respectively.

[0041] (3) Bond the metal series layer of the core material obtained by hot pressing to the surface of the viscous silicone rubber, then put it into a die cutting lathe for die cutting, and perform die cutting on the surface of the metal electrode layer. First, cut along the first cutting path to obtain a single core material. The spacing of the first cutting path is 1.00 mm, and the cutting depth is 0.32 mm. Then cut out a blocking groove along the second cutting path. The second cutting path is parallel and centered between two adjacent first cutting paths, the cutting depth is 0.06 mm, and the width of the blocking groove is 0.30 mm. Finally, cut along the third cutting path with a spacing of 0.50 mm and perpendicular to the first cutting path to obtain a PPTC mounting device with a series structure.

[0042] Comparative Example 2

[0043] The preparation of a traditional PPTC mounting device, and the preparation steps are as follows:

[0044] (1) Prepare a PPTC thin film by the melting method. Put 10 g of polyamide and 140 g of titanium carbide into an extruder, and extrude and mold them into a PPTC composite material thin film after high-temperature melting and mixing.

[0045] (2) Press and bond in the order of an aluminum foil layer, a PPTC composite material layer, and an aluminum foil layer through a hot pressing process to obtain a conductive composite material core layer with a positive temperature coefficient effect.

[0046] (3) Drill characters on the surface of the conductive composite material core layer for positioning purposes.

[0047] (4) Place the conductive composite core layer in a circuit board grinding machine and mark the inner layer circuit with chemical solution, then put it into a laminating machine to paste the photosensitive film and perform exposure.

[0048] (5) Etch the inner layer circuit with corrosive chemical solution in an etching machine.

[0049] (6) Use a screen printing machine to print solder mask ink on the upper and lower surfaces of the conductive composite core layer with the inner layer circuit etched, and cure it at 150 °C for 1 h.

[0050] (7) Cut into PPTC mounting devices with dimensions of 1.00 mm * 0.50 mm.

[0051] Example 3

[0052] (1) Dissolve polyvinylidene fluoride, carbon black and N,N-dimethylformamide completely and mix them evenly according to the mass ratio of 1:2:6 to obtain PPTC ink, then scrape it on a 50-μm-thick copper foil and place it in a vacuum drying oven at 75 °C to completely volatilize the solvent, obtaining a metal electrode layer and a metal series layer covered with a PPTC composite layer about 200 μm thick.

[0053] (2) Bond the metal electrode layer and the metal series layer covered with the PPTC composite layer to each other, and put them into a hot press for hot pressing. The hot pressing temperature is 180 °C and the hot pressing pressure is 4 MPa, obtaining a core material with a PPTC composite layer in the middle, and a metal series layer and a metal electrode layer on the upper and lower layers respectively.

[0054] (3) Bond the metal series layer of the core material obtained by hot pressing to the surface of the viscous silicone rubber, then put it into a cutting lathe for cutting, and perform cutting on the surface of the metal electrode layer. First, cut along the first cutting track to obtain a single core material. The spacing of the first cutting tracks is 1.40 mm and the cutting depth is 0.30 mm. Then, cut out the blocking grooves along the second cutting track. The second cutting track is parallel and centered between two adjacent first cutting tracks, the cutting depth is 0.05 mm, and the width of the blocking groove is 0.30 mm. Finally, cut along the third cutting track with a spacing of 0.70 mm and perpendicular to the first cutting track to obtain a PPTC mounting device with a series structure.

[0055] Comparative Example 3

[0056] The preparation of a traditional PPTC mounting device, and the preparation steps are as follows:

[0057] (1) Prepare a PPTC film by the melting method. Put 10 g of polyvinylidene fluoride and 20 g of carbon black into an extruder, and extrude and form a PPTC composite film after high-temperature melting and mixing.

[0058] (2) The conductive composite core layer with positive temperature coefficient effect is obtained by hot pressing in the order of copper foil layer, PPTC composite material layer and copper foil layer.

[0059] (3) Drilling words on the surface of the conductive composite core layer for positioning purposes.

[0060] (4) Place the conductive composite core layer in a circuit board grinding machine and mark the inner layer circuit with chemical solution, then put it into a laminating machine to paste the photosensitive film and perform exposure.

[0061] (5) Etch the inner layer circuit with corrosive chemical solution in an etching machine.

[0062] (6) Use a screen printing machine to print solder mask ink on the upper and lower surfaces of the conductive composite core layer with the inner layer circuit etched and cure it at 150 °C for 1 h.

[0063] (7) Cut into PPTC mounting devices with dimensions of 1.40 mm * 0.70 mm.

[0064] Refer to the following table:

[0065]

[0066] Table 1 Performance comparison between the series-connected structure PPTC mounting device prepared by the present invention and the traditional PPTC device

[0067] In summary: Compared with the traditional PPTC mounting device, it can provide a longer conduction path under the same size, effectively improving the withstand voltage performance. At the same time, the manufacturing process has been significantly simplified, providing a feasible solution for the efficient preparation of ultra-small high withstand voltage performance PPTC mounting devices.

Claims

1. A PPTC mounting device with a series structure, characterized in that: include: The three-layer structure comprises a metal series connection layer, a PPTC composite material layer and a metal electrode layer, wherein the metal series connection layer is the top layer, the PPTC composite material layer is the middle layer, and the metal electrode layer is the bottom layer; the metal electrode layer comprises two sheets, the two metal electrode layers are horizontally distributed and a gap is provided in the middle, and the gap is a blocking groove.

2. A PPTC mounting device of series structure as claimed in claim 1, characterized in that: The PPTC composite material layer is prepared by printing with PPTC ink; the metal series layer and the metal electrode layer are one of copper foil, silver foil, aluminum foil, nickel foil, nickel-plated copper foil and tin-plated copper foil.

3. A PPTC mounting device of series structure as claimed in claim 2, characterized in that: The PPTC ink comprises 1 to 5 parts of a polymer matrix, 2 to 20 parts of a conductive filler, and 5 to 20 parts of a solvent, which are uniformly mixed by ball milling.

4. A PPTC mounting device of series structure as claimed in claim 3, characterized in that: The polymer matrix includes one or more mixtures of polyethylene and its copolymers, polypropylene and its copolymers, polyvinylidene fluoride and its copolymers, polycarbonate and its copolymers, polyethylene terephthalate and its copolymers, and polyamide and its copolymers; the conductive filler includes one or more mixtures of silver nanowires, carbon black, acetylene black, short-cut carbon fibers, long-cut carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphite, titanium carbide, tungsten carbide, tantalum carbide, titanium nitride, titanium diboride, aluminum nitride, magnesium nitride, and boron nitride; the solvent is a mixture of one or more mixtures selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, diphenylamine, toluene, xylene, diethylene glycol ethyl ether, m-cresol, and phenol.

5. A method for preparing a PPTC mounting device with a series structure, characterized in that: The following steps are involved: S1: Printing PPTC ink on the metal series connection layer by screen printing or doctor blade coating and drying to obtain a metal series connection layer covered with a PPTC composite material layer; S2: Printing the PPTC ink on the metal electrode layer by screen printing or doctor blade coating and drying to obtain a metal electrode layer covered with a PPTC composite material layer; S3: hot pressing two metal series connection layers and metal electrode layers covered with PPTC composite material layers to obtain a core material in which the middle layer is the PPTC composite material layer and the upper and lower layers are the metal series connection layer and the metal electrode layer respectively; S4: bonding the metal series layer of the core material in S3 to the surface of the silicone rubber; S5: Slice the surface of the metal electrode layer to cut the core material into a single piece of PPTC mounting device, and cut out the blocking groove at the same time: S51: cutting along the first cutting path to obtain a single core material; S52: cutting a blocking groove along the second cutting path; S53: Cut along the third cutting path to obtain a PPTC mounting device.

6. The method for preparing a PPTC SMD device of a series structure as claimed in claim 5, characterized in that: The PPTC mounting device of the series structure has a width of d and a length of D, and a blocking groove width of 0.1 to 0.3 times of D.

7. The method for preparing a PPTC SMD device with a series structure as claimed in claim 5, characterized in that: The PPTC ink drying temperature is 70-95°C; the hot pressing temperature is 150-200°C.

8. The method for preparing a PPTC SMD device with a series structure as claimed in claim 5, characterized in that: The first scribing lines are spaced apart by D, the second scribing lines are centered between two adjacent first scribing lines, and the third scribing lines are spaced apart by d and are perpendicular to the first scribing lines.

9. The method for preparing a PPTC SMD device with a series structure as claimed in claim 8, characterized in that: The first and third scribing lines should scribble through the top, middle and bottom layers, and the second scribing line should scribble through the bottom electrode layer without damaging the PPTC composite material layer.

10. According to claim 1- A PPTC mounting device with a series structure as described in any one of claims 4 or claims 5- 9. The application of a PPTC SMD device in a series structure obtained by the method for preparing a PPTC SMD device in a series structure as described in any one of the items in the field of overcurrent and overheat protection is characterized in that: The PPTC mounting device in the series structure is connected to a circuit to play a circuit protection function.

Images