Over-current protection device with six plastic-packaged surfaces and preparation method of over-current protection device

Abstract

The invention provides an overcurrent protection device with six plastic-packaged surfaces and a preparation method thereof, and belongs to the technical field of semiconductors, and the overcurrent protection device comprises an overcurrent protection chip, the six surfaces of which are coated with plastic packaging layers; the conductive pad electrode is positioned on the first surface and / or the second surface of the plastic packaging layer; a conductive pad formed on the conductive pad electrode; and the via holes are formed at the two ends of the plastic packaging layer and are electrically connected with the overcurrent protection chip, the conductive bonding pad electrode and the conductive bonding pad respectively to form a conductive loop. The beneficial effects of the invention are that the plastic package layer completely isolates the direct contact between the internal chip of the component and any external substance, and because of the coating of the plastic package layer, the expansion and aging of the core material can be greatly limited, the through-current capability of the component is improved, the lift resistance of multiple protection of the component is reduced, and the recoverable capability of the component is improved. And the composite material has higher environment-resistant reliability and long-term charge-discharge service life, and can be widely applied to harsh specific environments and electronic equipment with great reliability requirements on components.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a six-sided plastic-sealed overcurrent protection device and a preparation method thereof. Background Art

[0002] With the diversified development of smart devices, the application environment and conditions are becoming more and more complex and demanding, and electronic components are also facing greater challenges and opportunities.

[0003] At present, the conductive particles in the positive temperature coefficient (PTC) chipset of overcurrent protection devices on the market are prone to oxidation and aging, and the conductive composite core material is prone to expansion and aging. The device has low current capacity, low stability and short service life. It has poor application ability in harsh specific environments such as high temperature and high humidity and in electronic products with strict reliability requirements. How to improve the environmental resistance and reliability of products and expand the application areas of products has become the development direction of various electronic component manufacturers. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a six-sided plastic-sealed overcurrent protection device and a preparation method thereof.

[0005] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0006] A six-sided plastic-sealed overcurrent protection device, comprising:

[0007] An overcurrent protection chip, wherein six surfaces of the overcurrent protection chip are all covered with a plastic sealing layer, and the plastic sealing layer includes a first surface and a second surface opposite to each other;

[0008] A conductive pad electrode, located on the first surface and / or the second surface of the plastic packaging layer, and divided into two left and right pad electrodes that are not electrically connected;

[0009] A conductive pad formed on each of the conductive pad electrodes;

[0010] The via holes are formed in the plastic packaging layer at both ends, and the via holes are electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad respectively to form a conductive loop.

[0011] Preferably, the overcurrent protection chip comprises a positive temperature coefficient chipset, and the positive temperature coefficient chipset comprises at least one;

[0012] Each of the positive temperature coefficient chipsets comprises:

[0013] a composite core layer, the composite core layer comprising opposing first and second surfaces;

[0014] A first electrode layer formed on a first surface of the composite core material layer;

[0015] The second electrode layer is formed on the second surface of the composite core material layer.

[0016] Preferably, one of the first electrode layer and the second electrode layer is electrically connected to the via at one end, and the other electrode layer is electrically connected to the via at the other end; or

[0017] One of the first electrode layer and the second electrode layer is electrically isolated from the vias at both ends, and the other electrode layer is divided into two electrodes, one of the two electrodes is electrically connected to the via at one end, and the other electrode is electrically connected to the via at the other end.

[0018] Preferably, the positive temperature coefficient chipset comprises one; or

[0019] The positive temperature coefficient chip set includes more than two, and the more than two positive temperature coefficient chip sets are stacked in parallel to form the overcurrent protection chip.

[0020] Preferably, the volume resistivity of the composite core material layer is less than 0.001 Ω.m.

[0021] Preferably, the plastic sealing layer is formed by plastic sealing the plastic sealing material once or multiple times.

[0022] Preferably, the plastic encapsulation material is selected from one or more combinations of epoxy resin, phenolic resin, polyimide board, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester.

[0023] Preferably, the through hole passes through the conductive pad, the conductive pad electrode, the plastic packaging layer and the overcurrent protection chip.

[0024] Preferably, the conductive through hole is exposed on the surface of the plastic packaging layer to achieve tin creep connection in a subsequent welding process.

[0025] The present invention also provides a method for preparing a six-sided plastic-sealed overcurrent protection device, which is used to prepare the six-sided plastic-sealed overcurrent protection device as described above, comprising:

[0026] Step S1, weaving a plurality of overcurrent protection chips into a reel, arranging them in a matrix form and sticking them on a piece of tape, wherein the plurality of overcurrent protection chips have preset gaps in the horizontal and vertical directions;

[0027] Step S2, placing the tape with the overcurrent protection chip attached thereto in a plastic sealing machine for integrated plastic sealing, coating the surface of the overcurrent protection chip except the surface with the tape attached thereto with the plastic sealing material, and filling the gaps between the chips with the plastic sealing material;

[0028] Step S3, peeling off the tape, placing it in the plastic sealing machine again for integrated plastic sealing, so that six surfaces of the overcurrent protection chip form a plastic sealing layer;

[0029] Step S4, laminating copper foil on the first surface and / or the second surface of the plastic encapsulation layer, and pressing the copper foil to form a conductive pad electrode, wherein the conductive pad electrode is divided into two left and right pad electrodes that are not electrically connected, and a conductive pad is formed on each of the conductive pad electrodes;

[0030] Step S5, forming through holes at both ends of the plastic encapsulation layer by drilling, the through holes passing through the conductive pad, the conductive pad electrode, the plastic encapsulation layer and the overcurrent protection chip, and plating a conductive material in the through holes to form a via hole, the via hole is electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad, respectively, to form a conductive loop;

[0031] Step S6, cutting along the cutting paths between the conductive pads to form an overcurrent protection device with six-sided plastic sealing.

[0032] The advantages or beneficial effects of the technical solution of the present invention are:

[0033] The present invention protects all six sides of the overcurrent protection chip through a plastic sealing layer, thereby completely isolating the internal chip of the component from direct contact with any external substance, and can prevent the internal chip from being chemically and physically damaged by related gases or liquids. In addition, due to the coating of the plastic sealing layer, the expansion and aging of the core material of the conductive composite material can be greatly limited, the current carrying capacity of the device can be improved, the resistance of the device for multiple protections can be reduced, the recoverability of the device can be improved, and it has higher environmental reliability and long-term charge and discharge life, and can be widely used in harsh specific environments and electronic equipment with extremely high reliability requirements for components. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a three-dimensional schematic diagram of an overcurrent protection device in a preferred embodiment 1 of the present invention;

[0035] Figure 2 It is a cross-sectional schematic diagram of an overcurrent protection device in a preferred embodiment 1 of the present invention;

[0036] Figure 3 It is a three-dimensional schematic diagram of an overcurrent protection device in a preferred embodiment 2 of the present invention;

[0037] Figure 4It is a cross-sectional schematic diagram of an overcurrent protection device in a preferred embodiment 2 of the present invention;

[0038] Figure 5 It is a three-dimensional schematic diagram of an overcurrent protection device in a preferred embodiment 3 of the present invention;

[0039] Figure 6 It is a cross-sectional schematic diagram of an overcurrent protection device in a preferred embodiment 3 of the present invention;

[0040] Figure 7 It is a three-dimensional schematic diagram of an overcurrent protection device in a preferred embodiment 4 of the present invention;

[0041] Figure 8 It is a cross-sectional schematic diagram of the overcurrent protection device in the preferred embodiment 4 of the present invention.

[0042] Description of reference numerals:

[0043] In Example 1:

[0044] 10: Resistive positive temperature effect conductive composite core material of overcurrent protection chip;

[0045] 20a: upper electrode of the overcurrent protection chip;

[0046] 20b: lower electrode of the overcurrent protection chip;

[0047] 60a, 60c: first conductive pad electrodes at the upper and lower left ends;

[0048] 60b, 60d: second conductive pad electrodes at the upper and lower right ends;

[0049] 70a, 70c: first conductive pad electrodes at the upper and lower left ends;

[0050] 70b, 70d: second conductive pad electrodes at the upper and lower right ends;

[0051] 40: plastic sealing layer;

[0052] 30a: etching insulation seam of upper electrode of overcurrent protection chip;

[0053] 30b: etching insulation seam of lower electrode of overcurrent protection chip;

[0054] 50a: first conductive hole;

[0055] 50b: second conductive hole;

[0056] In Example 2:

[0057] 11: Resistive positive temperature effect conductive composite core material of overcurrent protection chip; 21a: Upper electrode of overcurrent protection chip;

[0058] 21b: a first lower electrode of the overcurrent protection chip;

[0059] 21c: a second lower electrode of the overcurrent protection chip;

[0060] 61a, 61c: first conductive pad electrodes at the upper and lower left ends;

[0061] 61b, 61d: second conductive pad electrodes at the upper and lower right ends;

[0062] 71a, 71c: first conductive pad electrodes at the upper and lower left ends;

[0063] 71b, 71d: second conductive pad electrodes at the upper and lower right ends;

[0064] 41: plastic sealing layer;

[0065] 31a: Etching insulation seam at the left end of the upper electrode of the overcurrent protection chip;

[0066] 31b: Etching an insulating seam at the right end of the upper electrode of the overcurrent protection chip;

[0067] 31c: etching insulation seam of lower electrode of overcurrent protection chip;

[0068] 51a: first conductive hole;

[0069] 51b: second conductive hole;

[0070] In Example 3:

[0071] 12: The resistive positive temperature effect conductive composite material core material of the overcurrent protection chip;

[0072] 13: the resistive positive temperature effect conductive composite material core material of the lower overcurrent protection chip; 22a: the first upper electrode of the upper overcurrent protection chip;

[0073] 22b: a second upper electrode of the upper overcurrent protection chip;

[0074] 22c: lower electrode of the upper overcurrent protection chip;

[0075] 23a: a first lower electrode of the lower overcurrent protection chip;

[0076] 23b: a second lower electrode of the lower overcurrent protection chip;

[0077] 23c: upper electrode of the lower overcurrent protection chip;

[0078] 62a, 62c: first conductive pad electrodes at the upper and lower left ends;

[0079] 62b, 60d: second conductive pad electrodes at the upper and lower right ends;

[0080] 72a, 72c: first conductive pad electrodes at the upper and lower left ends;

[0081] 72b, 72d: second conductive pad electrodes at the upper and lower right ends;

[0082] 42: plastic sealing layer;

[0083] 32a: etching insulation seam of upper electrode of upper overcurrent protection chip;

[0084] 32b: etching an insulating seam at the left end of the lower electrode of the upper overcurrent protection chip;

[0085] 32c: etching an insulating seam at the right end of the lower electrode of the upper overcurrent protection chip;

[0086] 33a: etching insulation seam of lower electrode of lower overcurrent protection chip;

[0087] 33b: etching an insulating seam at the left end of the upper electrode of the lower overcurrent protection chip;

[0088] 33c: etching an insulating seam at the right end of the upper electrode of the lower overcurrent protection chip;

[0089] 80: insulating material between the lower electrode of the upper core material and the upper electrode of the lower core material;

[0090] 52a: first conductive hole;

[0091] 52b: second conductive hole;

[0092] In Example 4

[0093] 14: The resistive positive temperature effect conductive composite material core material of the overcurrent protection chip;

[0094] 15: The core material of the conductive composite material with positive temperature effect of the resistance of the lower overcurrent protection chip;

[0095] 24a: lower electrode of the upper overcurrent protection chip;

[0096] 24b: upper electrode of the upper overcurrent protection chip;

[0097] 25a: upper electrode of the lower overcurrent protection chip;

[0098] 25b: lower electrode of the lower overcurrent protection chip;

[0099] 63a, 63c: first conductive pad electrodes at the upper and lower left ends;

[0100] 63b, 63d: second conductive pad electrodes at the upper and lower right ends;

[0101] 73a, 73c: first conductive pad electrodes at the upper and lower left ends;

[0102] 73b, 73d: second conductive pad electrodes at the upper and lower right ends;

[0103] 43: plastic sealing layer;

[0104] 34a: etching insulation seam of upper electrode of upper overcurrent protection chip;

[0105] 34b: etching insulation seam of lower electrode of upper overcurrent protection chip;

[0106] 35a: etching insulation seam of lower electrode of lower overcurrent protection chip;

[0107] 35b: etching insulation seam of upper electrode of lower overcurrent protection chip;

[0108] 81: insulating material between the lower electrode of the upper core material and the upper electrode of the lower core material;

[0109] 53a: first conductive hole;

[0110] 53b: second conductive hole. DETAILED DESCRIPTION

[0111] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0112] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0113] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0114] It should be noted that, for the sake of clarity, components at different positions in the same embodiment and the same components in different embodiments are separately indicated by different reference numerals in the following text.

[0115] The present invention aims to develop a new type of surface mount PTC, which is suitable for high current product applications and has extremely high environmental resistance reliability. It can replace the original dual IC and dual MOS solutions, greatly reduce the cost of terminal selection, and further broaden the application field of PTC and increase market share.

[0116] See also Figure 1In a preferred embodiment of the present invention, based on the above problems existing in the prior art, a six-sided plastic-sealed overcurrent protection device is provided, comprising an overcurrent protection chip, a plastic sealing layer covering six sides of the overcurrent protection element, conductive pads on the upper and lower surfaces, and left and right conductive through holes; wherein, it includes:

[0117] An overcurrent protection chip, wherein six surfaces of the overcurrent protection chip are all covered with a plastic sealing layer, and the plastic sealing layer includes a first surface and a second surface opposite to each other;

[0118] A conductive pad electrode, located on the first surface and / or the second surface of the plastic packaging layer, is divided into two left and right pad electrodes that are not electrically connected;

[0119] a conductive pad formed on each conductive pad electrode;

[0120] The via holes are formed in the plastic sealing layers at both ends, and the via holes are electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad respectively to form a conductive loop.

[0121] Specifically, the device provided in the embodiment of the present invention is a surface mounted component, and its upper and lower surfaces and four sides are protected by a plastic sealing layer, which can achieve 100% sealing protection, thereby improving the flow capacity and environmental resistance reliability of the overcurrent protection component;

[0122] The conductive pads are located on the plastic sealing surface of the upper and lower overcurrent protection chips after plastic sealing, and are used for surface mounting on the circuit board. Double-sided welding is adopted, and there is no need to distinguish between the front and back sides, which improves the efficiency of the production process and facilitates the installation and use of the client.

[0123] The conductive through-hole is located on the sides of both ends of the device, passes through the overcurrent protection chip inside the device, and is connected to the electrodes and conductive pads of the overcurrent protection chip to form an electrical conduction loop; in addition, the conductive through-hole also passes through the plastic sealing layer at both ends of the device and is not completely buried in the plastic sealing layer, but exposed to the plastic sealing layer, so that when the device is subsequently soldered to the circuit board, tin can creep into the conductive through-hole, reducing the skewness of the device welding and increasing the thrust resistance of the component after welding, with strong solderability and push and pull resistance after welding.

[0124] As a preferred embodiment, the overcurrent protection chip includes a positive temperature coefficient chip set, and the positive temperature coefficient chip set includes at least one;

[0125] Each PTC chipset includes:

[0126] a composite core material layer, the composite core material layer comprising a first surface and a second surface opposite to each other;

[0127] A first electrode layer, formed on a first surface of the composite core material layer, is an upper electrode;

[0128] The second electrode layer is formed on the second surface of the composite core material layer and is the lower electrode.

[0129] Specifically, the overcurrent protection chip is composed of at least one resistive positive temperature effect conductive composite material core, and the four sides and the upper and lower surfaces are all covered in a plastic sealing layer, thereby completely isolating the internal chip of the component from direct contact with any external substance, avoiding chemical and physical damage. The plastic sealing layer can also limit the expansion and aging of the conductive composite material core, improve the current carrying capacity of the device, reduce the resistance rise of the device for multiple protections, improve the recoverability of the device, and have higher environmental reliability and long-term charge and discharge life.

[0130] Furthermore, the composite core material layer adopts a resistive positive temperature effect conductive composite core material, wherein the volume fraction of the polymer in the conductive composite material base layer is between 20% and 75%, and is selected from one of polyethylene, chlorinated polyethylene, oxidized polyethylene, polyvinyl chloride, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polystyrene, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, polyformaldehyde, phenolic resin, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polytrifluoroethylene, polyvinyl fluoride, maleic anhydride grafted polyethylene, polypropylene, polyvinylidene fluoride, epoxy resin, ethylene-vinyl acetate copolymer, polymethyl methacrylate, ethylene-acrylic acid copolymer and a mixture thereof.

[0131] Preferably, in the resistive positive temperature effect conductive composite core material, the conductive filler is selected from one of carbon black, graphite, carbon fiber, carbon nanotube, metal powder, conductive ceramic powder and a mixture thereof.

[0132] Preferably, the metal powder is selected from: copper, nickel, tungsten, tin, silver, gold or alloys thereof and mixtures thereof.

[0133] Preferably, the conductive ceramic powder is selected from: metal nitride, metal carbide, metal boride, metal silicide or a mixture of the two or more thereof.

[0134] As a preferred embodiment, one of the first electrode layer and the second electrode layer is electrically connected to the via hole at one end, and the other electrode layer is electrically connected to the via hole at the other end; or

[0135] One of the first electrode layer and the second electrode layer is electrically isolated from the via holes at both ends, and the other electrode layer is divided into two electrodes, one of the two electrodes is electrically connected to the via hole at one end, and the other electrode is electrically connected to the via hole at the other end.

[0136] As a preferred embodiment, the positive temperature coefficient chipset includes one; or

[0137] The positive temperature coefficient chip set includes more than two positive temperature coefficient chip sets, which are stacked in parallel to form an overcurrent protection chip.

[0138] Specifically, the overcurrent protection chip may be a single-layer positive temperature coefficient chip set, or may be a chip set formed by stacking two or more layers of positive temperature coefficient chip sets in parallel.

[0139] Furthermore, in the parallel stacked chipset, each layer of the positive temperature coefficient chipset is sandwiched between a layer of insulating material and pressed together using a pressure transfer technology.

[0140] Preferably, the insulating material is selected from one or a combination of epoxy resin, phenolic resin, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin.

[0141] As a preferred embodiment, the volume resistivity of the composite core material layer is less than 0.001 Ω.m.

[0142] As a preferred embodiment, the plastic sealing layer is formed by plastic sealing the plastic sealing material once or multiple times.

[0143] Specifically, the plastic sealing layer can be plastic sealed once or multiple times and is attached to the surface of the overcurrent protection chip. The plastic sealing layer plastic seals the surfaces of the six sides of the overcurrent protection chip by integral injection molding.

[0144] Preferably, the injection molding method can be one or a combination of compression molding, compression molding, injection molding, transfer molding, and thermosetting molding.

[0145] As a preferred embodiment, the plastic encapsulation material is selected from one or more combinations of epoxy resin, phenolic resin, polyimide board, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester.

[0146] In this embodiment, the conductive pad can be formed by chemical deposition, spraying, sputtering, electroplating or a combination of these processes.

[0147] In this embodiment, the conductive pad may be made of zinc, copper, nickel, cobalt, iron, tungsten, tin, lead, silver, gold, platinum or alloys thereof, or a mixture thereof.

[0148] As a preferred embodiment, the via hole penetrates the conductive pad, the conductive pad electrode, the plastic packaging layer and the overcurrent protection chip.

[0149] As a preferred embodiment, the conductive through hole is exposed on the surface of the plastic packaging layer to achieve tin creep connection in the subsequent welding process.

[0150] Specifically, the via hole is a through hole drilled from top to bottom, and tin can creep into the hole after welding to enhance resistance to welding thrust.

[0151] The via hole can be drilled by mechanical drilling or burned by laser, and a conductive metal layer is attached to the surface of the hole. The shape of the via hole can be any regular or irregular shape.

[0152] The present invention also provides a method for preparing a six-sided plastic-sealed overcurrent protection device, which is used to prepare the six-sided plastic-sealed overcurrent protection device as described above, comprising:

[0153] Step S1, tape a plurality of overcurrent protection chips into a reel, arrange them in a matrix form and stick them on a piece of tape, with the plurality of overcurrent protection chips having preset gaps in the horizontal and vertical directions;

[0154] Further, the overcurrent protection chip includes a positive temperature coefficient chipset, and the positive temperature coefficient chipset includes at least one;

[0155] The preparation steps of each positive temperature coefficient chip set include:

[0156] A composite core material layer with a positive temperature effect of resistance is manufactured, and metal foils are respectively attached to the first and second surfaces opposite to each other of the composite core material layer as a first electrode layer and a second electrode layer, and a positive temperature coefficient chip set is manufactured by lamination;

[0157] The positive temperature coefficient chip set is cross-linked by gamma ray (Co60) or electron beam irradiation, with a dose of 10 to 150 Mrad;

[0158] The surface of the positive temperature coefficient chipset is etched according to a preset pattern by chemical etching, and unnecessary parts of the electrode foil are removed to form a positive temperature coefficient chipset with a preset pattern arranged in a preset matrix as an overcurrent protection chip.

[0159] If a multi-layer parallel stacked chip group is produced, an additional pressing step is performed to sandwich a layer of semi-cured insulating sheet between the positive temperature coefficient chip groups with etched patterns on each layer. After being pressed together through a pressing process, it is used as an overcurrent protection chip.

[0160] The prepared overcurrent protection chip sheet is cut into individual overcurrent protection chips, taped into reels, and then arranged in a certain matrix manner on a piece of tape by an automatic placement machine, leaving a gap of 0.1 to 0.5 mm between the chips in the horizontal and vertical directions.

[0161] Step S2, placing the tape with the overcurrent protection chip attached thereto in a plastic sealing machine for integrated plastic sealing, coating the surface of the overcurrent protection chip except the surface with the tape attached thereto with plastic sealing material, and filling the gaps between the chips with the plastic sealing material;

[0162] The whole tape with the chip attached is placed in an automatic plastic sealing machine, and the chips are plastic sealed as a whole to fill the gaps between the chips and plastic seal the upper surface of the chips.

[0163] Step S3, peeling off the tape and placing it in a plastic sealing machine again for integrated plastic sealing, so that six surfaces of the overcurrent protection chip form a plastic sealing layer;

[0164] The adhesive tape is peeled off, and the previously plastic-sealed product is placed upside down in a plastic sealing machine, and then plastic-sealed again as a whole, and the lower surface of the chip is also plastic-sealed and covered.

[0165] Step S4, pasting copper foil on the first surface and / or the second surface of the plastic packaging layer, and pressing the copper foil to form a conductive pad electrode, the conductive pad electrode is divided into two left and right pad electrodes that are not electrically connected, and a conductive pad is formed on each conductive pad electrode;

[0166] Among them, after the completely plastic-sealed product is taken out, a 1OZ copper foil is pasted on the top and bottom, and then pressed tightly into one by a pressing device.

[0167] Step S5, forming through holes at both ends of the plastic sealing layer by drilling, the through holes penetrate the conductive pad, the conductive pad electrode, the plastic sealing layer and the overcurrent protection chip, and plating a conductive material in the through holes to form a via hole, the via hole is electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad respectively to form a conductive loop;

[0168] Among them, through holes are drilled at both ends of each chip, passing through the upper and lower copper foils, plastic packaging materials and internal chips, and copper is plated in the holes to make them conductive through holes. Then, part of the copper on the upper and lower surfaces of the copper foil is etched away by chemical etching, leaving only the electrodes at the conductive pads. Then, a layer of metal is plated on the surfaces of the electrodes at the conductive pads and the conductive through holes by chemical deposition or electroplating to make a large finished core board.

[0169] Step S6, cutting along the cutting paths between the conductive pads to form an overcurrent protection device with six-sided plastic sealing.

[0170] Among them, a 0.1mm cutting blade is used to cut along the cutting path between the conductive pads to cut the entire finished chip into individual products, that is, the final overcurrent protection device with six-sided plastic sealing.

[0171] The embodiment of the present invention can take into account the plastic encapsulation of the six surfaces of the device through the above solution, and retain the exposed via holes and the double-sided pads.

[0172] Four embodiments are provided below to further illustrate and describe the technical solution:

[0173] Example 1

[0174] The three-dimensional schematic diagram of the product structure of the overcurrent protection device of this embodiment is as follows: Figure 1 As shown, the cross section is shown as Figure 2 As shown, the overcurrent protection chip of this embodiment includes a layer of conductive composite material core material 10 with positive temperature effect of resistance, which covers the upper electrode 20a and the lower electrode 20b from top to bottom. The lower electrode 20b is electrically isolated from the second via 50b by an etched insulating seam 30b and is electrically connected to the first via 50a; the upper electrode 20a is electrically isolated from the first via 50a by an etched insulating seam 30a and is electrically connected to the second via 50b. The upper and lower first conductive pad electrodes 60a, 60c and the upper and lower first conductive pads 70a, 70c are all electrically connected to the first via 50a, and the upper and lower second conductive pad electrodes 60b, 60d and the upper and lower second conductive pads 70b, 70d are electrically connected to the second via 50b. The plastic encapsulation layer 40 covers the six sides of the overcurrent protection chip, and the conductive pad electrodes and conductive pads used for mounting on the circuit board are exposed. The vias pass through the plastic encapsulation layer and are staggeredly connected to the electrodes of the composite core material in the chip.

[0175] Figure 1 In order to show the internal chip morphology, the plastic sealing layer on the long side is made transparent to a certain extent, so only the plastic sealing layer on the top, bottom, left and right sides is shown. In fact, the front and back sides are also covered by the plastic sealing layer.

[0176] Example 2

[0177] The three-dimensional schematic diagram of the product structure of the overcurrent protection device of this embodiment is as follows: Figure 3 As shown, the cross section is shown as Figure 4 As shown, the overcurrent protection chip of this embodiment comprises a layer of conductive composite material core material 11 with positive temperature effect of resistance, which covers the upper electrode 21a and the lower electrodes 21b and 21c from top to bottom. The lower electrode is divided into a first lower electrode 21b and a second lower electrode 21c by an etched insulating seam 31c. The first lower electrode 21b is electrically connected to the first conductive hole 51a, and the second lower electrode 21c is electrically connected to the second conductive hole 51b. Insulating seams 31a and 31b are etched on both ends of the upper electrode 21a, which are electrically isolated from the first conductive hole 51a and the second conductive hole 51b. The upper and lower first conductive pad electrodes 61a and 61c and the upper and lower first conductive pads 71a and 71c are all electrically connected to the first conductive hole 51a, and the upper and lower second conductive pad electrodes 61b and 61d and the upper and lower second conductive pads 71b and 71d are electrically connected to the second conductive hole 51b. The plastic encapsulation layer 41 covers the six surfaces of the overcurrent protection chip, and is used for mounting the conductive pad electrodes on the circuit board and the conductive pads are exposed. The vias pass through the plastic encapsulation layer and are staggeredly connected to the electrodes of the composite core material in the chip.

[0178] Figure 3In order to show the internal chip morphology, the plastic sealing layer on the long side is made transparent to a certain extent, so only the plastic sealing layer on the top, bottom, left and right sides is shown. In fact, the front and back sides are also covered by the plastic sealing layer.

[0179] Example 3

[0180] The three-dimensional schematic diagram of the product structure of the overcurrent protection device of this embodiment is as follows: Figure 5 As shown, the cross section is shown as Figure 6 As shown, the overcurrent protection chip of this embodiment is a chip group of a double-layer chip stacked in parallel, including two layers of conductive composite material core materials 12 and 13 with a positive temperature effect of resistance. The upper composite core material 12 is pressed on the upper electrodes 22a, 22b and the lower electrode 22c from top to bottom, and the upper electrode is divided into a first upper electrode 22a and a second upper electrode 22b by an etched insulating seam 32a. The first upper electrode 22a is electrically connected to the first conductive hole 52a, and the second upper electrode 22b is electrically connected to the second conductive hole 52b. Insulating seams 32b and 32c are etched on both ends of the lower electrode 22c, which are electrically isolated from the first conductive hole 52a and the second conductive hole 52b. The lower composite core material 13 is pressed on the upper electrode 23c and the lower electrodes 23a and 23b from top to bottom. The lower electrode is divided into a first lower electrode 23a and a second lower electrode 23b by an etched insulating seam 33a. The first lower electrode 23a is electrically connected to the first conductive hole 52a, and the second lower electrode 23b is electrically connected to the second conductive hole 52b. Insulating seams 33b and 33c are etched on both ends of the upper electrode 23c, which are electrically isolated from the first conductive hole 52a and the second conductive hole 52b. A layer of insulating material 80 is sandwiched between the lower electrode of the upper core material and the upper electrode of the lower core material. The upper and lower chips are pressed together by heat transfer technology, and the etched insulating seams 32b, 32c, 33b, and 33c are filled. The upper and lower first conductive pad electrodes 62a, 62c and the upper and lower first conductive pads 72a, 72c are all electrically connected to the first via 52a, and the upper and lower second conductive pad electrodes 62b, 62d and the upper and lower second conductive pads 72b, 72d are electrically connected to the second via 52b. The plastic encapsulation layer 42 covers the six surfaces of the overcurrent protection chip, and the conductive pad electrodes and conductive pads for mounting on the circuit board are exposed to the outside, and the vias pass through the plastic encapsulation layer and are staggeredly connected to the electrodes of the composite core material in the chip.

[0181] Figure 5 In order to show the internal chip morphology, the plastic sealing layer on the long side is made transparent to a certain extent, so only the plastic sealing layer on the top, bottom, left and right sides is shown. In fact, the front and back sides are also covered by the plastic sealing layer.

[0182] Example 4

[0183] The three-dimensional schematic diagram of the product structure of the overcurrent protection device of this embodiment is as follows: Figure 7 As shown, the cross section is shown as Figure 8 As shown, the overcurrent protection chip of this embodiment is a chip set of a double-layer chip stacked in parallel, comprising two layers of conductive composite material core materials 14 and 15 with a positive temperature effect of resistance. The upper core material 14 is respectively pressed on the upper electrode 24b and the lower electrode 24a, and the upper electrode 24b is electrically isolated from the first conductive hole 53a by an etched insulating slit 34a, and is electrically connected to the second conductive hole 53b; the lower electrode 24a is electrically isolated from the second conductive hole 53b by an etched insulating slit 34b, and is electrically connected to the first conductive hole 53a. The lower core material 15 is respectively pressed on the upper electrode 25a and the lower electrode 25b, and the upper electrode 25a is electrically isolated from the second conductive hole 53b by an etched insulating slit 35b, and is electrically connected to the first conductive hole 53a; the lower electrode 25b is electrically isolated from the first conductive hole 53a by an etched insulating slit 35a, and is electrically connected to the second conductive hole 53b. A layer of insulating material 81 is sandwiched between the lower electrode of the upper core material and the upper electrode of the lower core material. The upper and lower chips are pressed together by heat transfer technology, and the etched insulating seams 34b and 35b are filled. The upper and lower first conductive pad electrodes 63a, 63c and the upper and lower first conductive pads 73a, 73c are electrically connected to the first via 53a, and the upper and lower second conductive pad electrodes 63b, 63d and the upper and lower second conductive pads 73b, 73d are electrically connected to the second via 53b. The plastic encapsulation layer 43 covers the six sides of the overcurrent protection chip, and the conductive pad electrodes and conductive pads used for mounting on the circuit board are exposed to the outside. The vias will pass through the plastic encapsulation layer and be staggeredly connected to the electrodes of the composite core material in the chip.

[0184] Figure 7 In order to show the internal chip morphology, the plastic sealing layer on the long side is made transparent to a certain extent, so only the plastic sealing layer on the top, bottom, left and right sides is shown. In fact, the front and back sides are also covered by the plastic sealing layer.

[0185] The above embodiments only show the structure of single-layer and double-layer overcurrent protection chip components. This method and structure can also be used to realize components of three-layer or more chips.

[0186] The advantages or beneficial effects of adopting the above technical solution are: the present invention protects all six sides of the overcurrent protection chip through the plastic sealing layer, thereby completely isolating the internal chip of the component from direct contact with any external substance, and can prevent the internal chip from being chemically and physically damaged by related gases or liquids. In addition, due to the coating of the plastic sealing layer, the expansion and aging of the conductive composite core material can be greatly limited, the current carrying capacity of the device can be improved, the resistance of the device for multiple protections can be reduced, the recoverability of the device can be improved, and it has higher environmental reliability and long-term charge and discharge life, and can be widely used in harsh specific environments and electronic equipment with extremely high reliability requirements for components.

[0187] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of this specification and illustrations should be included in the protection scope of the present invention.

Claims

1. A six-sided plastic-encapsulated overcurrent protection device, characterized in that: include: An overcurrent protection chip, wherein six surfaces of the overcurrent protection chip are all covered with a plastic sealing layer, and the plastic sealing layer includes a first surface and a second surface opposite to each other; A conductive pad electrode, located on the first surface and / or the second surface of the plastic packaging layer, and divided into two left and right pad electrodes that are not electrically connected; A conductive pad formed on each of the conductive pad electrodes; The via holes are formed in the plastic packaging layer at both ends, and the via holes are electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad respectively to form a conductive loop.

2. The six-sided plastic-sealed overcurrent protection device according to claim 1, characterized in that: The overcurrent protection chip includes a positive temperature coefficient chipset, and the positive temperature coefficient chipset includes at least one; Each of the positive temperature coefficient chipsets comprises: a composite core layer, the composite core layer comprising opposing first and second surfaces; A first electrode layer formed on a first surface of the composite core material layer; The second electrode layer is formed on the second surface of the composite core material layer.

3. The six-sided plastic-sealed overcurrent protection device according to claim 2, characterized in that: One of the first electrode layer and the second electrode layer is electrically connected to the conductive via at one end, and the other electrode layer is electrically connected to the conductive via at the other end; or One of the first electrode layer and the second electrode layer is electrically isolated from the vias at both ends, and the other electrode layer is divided into two electrodes, one of the two electrodes is electrically connected to the via at one end, and the other electrode is electrically connected to the via at the other end.

4. The six-sided plastic-sealed overcurrent protection device according to claim 2, characterized in that: The positive temperature coefficient chipset includes one; or The positive temperature coefficient chip set includes more than two, and the more than two positive temperature coefficient chip sets are stacked in parallel to form the overcurrent protection chip.

5. The six-sided plastic-sealed overcurrent protection device according to claim 2, characterized in that: The volume resistivity of the composite core material layer is less than 0.001 Ω.m.

6. The six-sided plastic-sealed overcurrent protection device according to claim 1, characterized in that: The plastic sealing layer is formed by plastic sealing material once or multiple times.

7. The six-sided plastic-sealed overcurrent protection device according to claim 6, characterized in that: The plastic encapsulation material is selected from one or more combinations of epoxy resin, phenolic resin, polyimide board, unsaturated polyester, epoxy resin modified by glass fiber or inorganic filler, phenolic resin modified by glass fiber or inorganic filler, polyimide modified by glass fiber or inorganic filler, and unsaturated polyester modified by glass fiber or inorganic filler.

8. The six-sided plastic-sealed overcurrent protection device according to claim 1, characterized in that: The via hole passes through the conductive pad, the conductive pad electrode, the plastic packaging layer and the overcurrent protection chip.

9. The six-sided plastic-sealed overcurrent protection device according to claim 1, characterized in that: The conductive through hole is exposed on the surface of the plastic sealing layer to achieve tin creep connection in the subsequent welding process.

10. A method for preparing a six-sided plastic-sealed overcurrent protection device, characterized in that: For preparing the six-sided plastic-sealed overcurrent protection device as claimed in any one of claims 1 to 9, comprising: Step S1, weaving a plurality of overcurrent protection chips into a reel, arranging them in a matrix form and sticking them on a piece of tape, wherein the plurality of overcurrent protection chips have preset gaps in the horizontal and vertical directions; Step S2, placing the tape with the overcurrent protection chip attached thereto in a plastic sealing machine for integrated plastic sealing, coating the surface of the overcurrent protection chip except the surface with the tape attached thereto with the plastic sealing material, and filling the gaps between the chips with the plastic sealing material; Step S3, peeling off the tape, placing it in the plastic sealing machine again for integrated plastic sealing, so that six surfaces of the overcurrent protection chip form a plastic sealing layer; Step S4, laminating copper foil on the first surface and / or the second surface of the plastic encapsulation layer, and pressing the copper foil to form a conductive pad electrode, wherein the conductive pad electrode is divided into two left and right pad electrodes that are not electrically connected, and a conductive pad is formed on each of the conductive pad electrodes; Step S5, forming through holes at both ends of the plastic encapsulation layer by drilling, the through holes passing through the conductive pad, the conductive pad electrode, the plastic encapsulation layer and the overcurrent protection chip, and plating a conductive material in the through holes to form a via hole, the via hole is electrically connected to the overcurrent protection chip, the conductive pad electrode and the conductive pad, respectively, to form a conductive loop; Step S6, cutting along the cutting paths between the conductive pads to form an overcurrent protection device with six-sided plastic sealing.

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