Preparation and packaging method of surface-mounted fuse and surface-mounted fuse

Abstract

The invention discloses a preparation and packaging method of a surface-mounted fuse and the surface-mounted fuse. The preparation and packaging method comprises the following steps: etching a plurality of top copper bonding pads and a plurality of bottom copper bonding pads on a macromolecular double-sided copper-clad substrate; drilling an electrical through hole penetrating through the top copper bonding pad and the corresponding bottom copper bonding pad at each copper bonding pad group; welding an alloy sheet between every two adjacent top copper bonding pads in each top copper bonding pad row; punching a plurality of hollow areas on a polymer substrate to obtain a hollow frame; placing a hollow frame on the top surface of the copper-clad substrate welded with the alloy sheet, and bonding the hollow frame and the copper-clad substrate; covering the hollow frame with a high-molecular top cover film, and carrying out thermocompression bonding to obtain a packaged semi-finished substrate; and cutting the semi-finished substrate along the cutting line to obtain a plurality of surface-mounted fuses. According to the invention, the preparation and packaging of a plurality of surface-mounted fuses can be realized at one time, so that the process can be simplified, the production efficiency can be improved, and electric arcs are not easy to generate under the scene of larger current.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surface mounting, and particularly relates to a preparation and packaging method of a surface-mounted fuse and the surface-mounted fuse. BACKGROUND

[0002] In recent years, the electronic industry has developed rapidly, and the progress of computer technology and communication technology is particularly remarkable. With the launch of more and more ultra-thin and ultra-small notebook computers and tablet computers, and the continuous improvement of battery capacity, the performance requirements for electronic components are increasingly demanding. Therefore, there is an urgent need for a large-current fuse component that must meet the miniaturization trend of the electronic industry and can meet the working requirements of large current.

[0003] At present, lithium ion batteries widely adopt two or more levels of charge and discharge protection circuits. The first level protection usually adopts the mode of IC (integrated circuit) combined with MOSFET (metal oxide semiconductor field effect transistor), which can basically realize overcurrent, overvoltage, anti-reverse charging and other protection functions. However, once the first level protection fails, the second level protection needs to play a necessary complementary role. At present, the second level protection methods include PTC (positive temperature coefficient thermistor), Breaker (breaker), SMD Fuse (surface mount fuse), temperature fuse, IC (integrated circuit) combined with MOSFET (metal oxide semiconductor field effect transistor) and self-control protector and other ways.

[0004] Chinese patent CN114446718A discloses a small-current high-molecular surface-mounted fuse and a preparation method thereof, which comprises the following steps: preparing a substrate, etching a fuse, printing a flux layer, printing a flame-retardant protective layer, cutting the substrate, printing an identification, and metallizing an end. The surface-mounted fuse has the following structure: a unit cell, a fuse, a flux layer, a flame-retardant protective layer, a side electrode, and an end electrode. The surface-mounted fuse prepared by the patent has no shell protection, and its application range is limited to circuits with small working current. However, in the case of large current, such fuses are prone to arc, thereby significantly increasing the risk of fire. SUMMARY

[0005] In view of the defects of the prior art, the application provides a preparation and packaging method of a surface-mounted fuse and the surface-mounted fuse, which can realize the preparation and packaging of multiple surface-mounted fuses at one time, thereby simplifying the process and improving the production efficiency, and is not prone to arc in the case of large current, and the prepared surface-mounted fuse is shock-resistant and not easy to break.

[0006] The technical solution adopted by the application to solve the technical problems is:

[0007] A preparation and packaging method of a surface-mounted fuse, comprising the following steps:

[0008] S1, etching a plurality of array-arranged top copper pads on a top copper foil layer of a high polymer double-sided copper-clad substrate and a plurality of bottom copper pads corresponding in number and position to the top copper pads on a bottom copper foil layer, each of the bottom copper pads and the corresponding top copper pad forming a copper pad group, and a plurality of the top copper pad groups arranged longitudinally in each column forming a top copper pad column; drilling a through hole through the top copper pad and the corresponding bottom copper pad at each of the copper pad groups; and welding an alloy sheet between every two adjacent top copper pads in each of the top copper pad columns;

[0009] S2, punching a plurality of hollowed-out regions corresponding in number and position to the alloy sheets on a high polymer substrate of a size matching that of the high polymer double-sided copper-clad substrate to obtain a hollow frame; and bonding the hollow frame to the top surface of the copper-clad substrate with the welded alloy sheets, wherein the frame of each of the hollowed-out regions surrounds the corresponding alloy sheet;

[0010] S3, covering a high polymer top cover film of a size matching that of the high polymer double-sided copper-clad substrate on the hollow frame, and obtaining a packaged semi-finished substrate through hot pressing; wherein the high polymer top cover film covers each of the hollowed-out regions of the hollow frame;

[0011] S4, the frame lines of the hollow frame, except for the frame lines at the edge positions, are referred to as inner frame lines, each of the inner frame lines extends through opposite edges of the hollow frame, and a plurality of the inner frame lines are arranged in a crisscross manner, the semi-finished substrate is cut along a cutting line corresponding in position to each of the inner frame lines to obtain a plurality of surface-mounting fuses, and two sub-bottom copper pads at the bottom of each of the surface-mounting fuses serve as working pads; wherein the frame line is a center line on the frame, and the frame line is the same as the extension direction of the corresponding frame.

[0012] Further,

[0013] In step S1, the high polymer double-sided copper-clad substrate has a thickness of less than 0.3 mm, and further comprises a high polymer film layer, the top copper foil layer is arranged at the top surface of the high polymer film layer, and the bottom copper foil layer is arranged at the bottom surface of the high polymer film layer.

[0014] In step S4, each of the surface-mounting fuses comprises a sub-high polymer film layer, the bottom surface of the sub-high polymer film layer is distributed with two sub-bottom copper pads, and the top surface is distributed with two sub-top copper pads, each of the sub-top copper pads corresponds in position to the corresponding sub-bottom copper pad and is electrically connected through an electrical through hole, the two sub-top copper pads are electrically connected through an alloy sheet, the alloy sheet is surrounded by the frame of the corresponding hollowed-out region, the hollowed-out region is covered by a sub-high polymer top cover film, and the alloy sheet is packaged.

[0015] Further,

[0016] In step S1, the material of the polymer film layer is one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer.

[0017] In step S2, the material of the polymer substrate is one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer, and the alloy sheet is made of two or more metals selected from tin, silver, lead, indium, copper and bismuth.

[0018] In step S3, the material of the polymer top cover film is one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer.

[0019] Further, in step S1, when etching the top copper foil layer, first, top protection films are attached to each top copper pad area of the top copper foil layer to form top copper foil protection areas, and the remaining areas of the top copper foil layer form top copper foil non-protection areas, then the top copper foil non-protection areas are etched away, and the polymer film layer is exposed, forming a plurality of top copper pads arranged in a longitudinal and horizontal array; when etching the bottom copper foil layer, first, bottom protection films are attached to each bottom copper pad area of the bottom copper foil layer to form bottom copper foil protection areas, and the remaining areas of the bottom copper foil layer form bottom copper foil non-protection areas, then the bottom copper foil non-protection areas are etched away, and the polymer film layer is exposed, forming a plurality of bottom copper pads.

[0020] Further, in step S1, each bottom copper pad is arranged symmetrically with the corresponding top copper pad; the top copper pads at the top edge of the polymer film layer are called edge top copper pads, and the remaining top copper pads are called inside top copper pads, a plurality of edge top copper pads are in the shape of a cuboid and have the same size, a plurality of inside top copper pads are in the shape of a cuboid and have the same size, the length of the edge top copper pad is half the length of the inside top copper pad, and the width and height of the edge top copper pad and the inside top copper pad are the same, wherein the length direction of the edge top copper pad and the inside top copper pad is the longitudinal direction, and the width direction of the edge top copper pad and the inside top copper pad is the transverse direction; the shape and size of each alloy sheet are adapted to the shape and size of the inside top copper pad.

[0021] Further, in step S2, the shape of each hollowed-out area is adapted to the shape of the alloy sheet, the length of the frame of the hollowed-out area is greater than the length of the alloy sheet, the width of the frame of the hollowed-out area is greater than the width of the alloy sheet, and the height of the frame of the hollowed-out area is greater than the height of the alloy sheet, and the geometric center of each hollowed-out area coincides with the geometric center of the corresponding alloy sheet.

[0022] Further,

[0023] The step S1 is specifically: etching a plurality of array-arranged top copper pads on the top copper foil layer of the polymer double-sided copper-clad substrate and a plurality of bottom copper pads on the bottom copper foil layer, the number of the bottom copper pads being equal to that of the top copper pads and the positions of the bottom copper pads corresponding to those of the top copper pads, each of the bottom copper pads and the corresponding top copper pad forming a copper pad group; drilling a plurality of through holes penetrating the top copper pad and the corresponding bottom copper pad at each of the copper pad groups, and electroplating a layer of copper on the inner wall of each of the through holes to obtain a plurality of electrical vias, wherein each of the edge copper pad groups is formed by each of the edge top copper pad and the corresponding bottom copper pad, and each of the inner side copper pad groups is formed by each of the inner side top copper pad and the corresponding bottom copper pad, for each of the edge copper pad groups, resin-burying the electrical vias on the edge copper pad group except for the electrical vias at the middle positions of the edge lines of the edge copper pad group, and for each of the inner side copper pad groups, resin-burying the electrical vias on the inner side copper pad group except for the electrical vias at the middle positions of the inner side copper pad group; electroplating a layer of nickel and tin on each of the top copper pads to obtain a plurality of top metal pads, and electroplating a layer of nickel and tin on each of the bottom copper pads to obtain a plurality of bottom metal pads, wherein each of the plurality of top metal pads in each column is combined to form a top metal pad column; and welding an alloy sheet between each two adjacent top metal pads in each of the top metal pad columns by using a reflow soldering process or a laser welding process, wherein each of the alloy sheets is coated with an organic solvent layer.

[0024] In the step S4, each of the cutting lines arranged in the transverse direction is located at the position of the electrical via at the middle of each of the corresponding top metal pads, and each of the two sub-bottom metal pads at the bottom of each of the surface-mounting fuses serves as a working pad, and each of the working pads is electrically connected to the corresponding sub-top metal pad at the top through the partial electrical via.

[0025] Further, in the step S1, the aperture size of each of the through holes is set according to the overcurrent specification of the surface-mounting fuse obtained in the step S4.

[0026] Further, the step S3 is specifically: covering a polymer top cover film coated with an adhesive and having a size suitable for that of the polymer double-sided copper-clad substrate on the hollow frame, and obtaining the packaged semi-finished substrate by vacuum hot pressing, wherein the polymer top cover film covers each of the hollowed-out areas of the hollow frame.

[0027] The surface mount fuse is prepared and packaged by the preparation and packaging method of the surface mount fuse, and comprises a sub-high molecular film layer, two sub-bottom copper pads are distributed at the bottom surface of the sub-high molecular film layer, and two sub-top copper pads are distributed at the top surface of the sub-high molecular film layer, each sub-top copper pad corresponds to a corresponding sub-bottom copper pad in position and is electrically connected through an electrical through hole, two sub-top copper pads are electrically connected through an alloy sheet, the alloy sheet is surrounded by a frame of a corresponding hollow area, the hollow area is covered by a sub-high molecular top cover film, and the frame of the hollow area, the sub-high molecular top cover film and the sub-high molecular film layer cooperatively form an encapsulation shell of the alloy sheet.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The preparation and packaging method of the surface mount fuse in the application comprises the following steps: S1, etching a plurality of array-arranged top copper pads on the top copper foil layer of the polymer double-sided copper-clad substrate and a plurality of bottom copper pads corresponding in position to the number of the top copper pads on the bottom copper foil layer, each bottom copper pad and the corresponding top copper pad forming a copper pad group, and a plurality of top copper pad groups arranged longitudinally in each column forming a top copper pad column; drilling a through hole through the top copper pad and the corresponding bottom copper pad at each copper pad group; welding an alloy sheet between every two adjacent top copper pads in each top copper pad column; S2, punching a plurality of hollow areas corresponding in position to the number of the alloy sheets on a polymer substrate with a size matching that of the polymer double-sided copper-clad substrate to obtain a hollow frame, and bonding the hollow frame to the top surface of the copper-clad substrate with the welded alloy sheets, wherein the frame of each hollow area surrounds the corresponding alloy sheet; S3, covering a polymer top cover film with a size matching that of the polymer double-sided copper-clad substrate on the hollow frame, and obtaining a packaged semi-finished substrate through hot pressing; S4, the frame lines in the hollow frame except for the edge position are referred to as inner frame lines, each inner frame line passes through the opposite edges of the hollow frame, and a plurality of inner frame lines are arranged in a crisscross manner, and the semi-finished substrate is cut along the cutting lines corresponding in position to the inner frame lines to obtain a plurality of surface mount fuses, and the two sub-bottom copper pads at the bottom of each surface mount fuse serve as working pads. In this way, the preparation of multiple surface mount fuses can be realized at one time, and through the cooperation of the frame of each hollow area in the hollow frame and the polymer top cover film, the alloy sheets of the surface mount fuses can be packaged simultaneously in the process of preparing the multiple surface mount fuses, thereby simplifying the process and improving the production efficiency, and since the alloy sheets of the surface mount fuses are in a packaged state, an electric arc is less likely to occur in a large-current scenario, thereby reducing the risk of fire; and since a flexible polymer double-sided copper-clad substrate is used instead of a traditional hard ceramic substrate, the problem of the ceramic substrate being fragile and not shock-resistant can be solved, so that the surface mount fuses prepared are shock-resistant and less likely to break, and the surface mount fuses will not bend and crack during use on a circuit board.

[0030] In the application, the shape of each hollow area is matched with the shape of the alloy sheet, the frame length of the hollow area is greater than the length of the alloy sheet, the frame width of the hollow area is greater than the width of the alloy sheet, the frame height of the hollow area is greater than the height of the alloy sheet, and the geometric center position of each hollow area coincides with the geometric center position of the corresponding alloy sheet. In this way, for each surface mount fuse, the frame of the hollow area will not touch the corresponding alloy sheet, and there is a certain gap between the frame of the hollow area and the corresponding alloy sheet, thereby facilitating energy dissipation when the alloy sheet is fused and preventing explosion, and ensuring that the alloy sheet is fused more completely. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A schematic diagram of the three-dimensional structure of the polymer double-sided copper-clad substrate in the present application;

[0032] Figure 2 A schematic diagram of the top copper foil layer of the polymer double-sided copper-clad substrate in the present application; Figure 1 A schematic diagram of the top copper pad etched on the top copper foil layer and the bottom copper pad etched on the bottom copper foil layer of the polymer double-sided copper-clad substrate in the present application;

[0033] Figure 3 A schematic diagram of the top copper pad etched on the top copper foil layer and the bottom copper pad etched on the bottom copper foil layer of the polymer double-sided copper-clad substrate in the present application; Figure 2 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0034] Figure 4 A schematic diagram of the through hole drilled through each copper pad group in the present application; Figure 3 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0035] Figure 5 A schematic diagram of the through hole drilled through each copper pad group in the present application; Figure 4 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0036] Figure 6 A schematic diagram of the through hole drilled through each copper pad group in the present application; Figure 5 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0037] Figure 7 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0038] Figure 8 A schematic diagram of the through hole drilled through each copper pad group in the present application; Figure 7 A schematic diagram of the through hole drilled through each copper pad group in the present application; Figure 6 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0039] Figure 9 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0040] Figure 10 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0041] Figure 11 A schematic diagram of the through hole drilled through each copper pad group in the present application;

[0042] The figure mark explanation: 1, polymer double-sided copper clad substrate, 101, top copper foil layer, 1011, top copper pad, 1012, top metal pad, 102, bottom copper foil layer, 1021, bottom metal pad, 103, polymer film layer, 1041, through hole, 1042, electrical through hole, 2, alloy sheet, 3, hollow frame, 301, hollow area, 302, frame, 4, polymer top cover film, 5, cutting line, 6, surface mount fuse, 601, sub-bottom metal pad, 602, sub-polymer film layer, 603, sub-polymer top cover film. DETAILED DESCRIPTION

[0043] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate the present application, and are not limiting to the present application.

[0044] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting to the present application. In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In addition, in the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0047] As Figures 1-11 shown, a preparation packaging method of a surface mount fuse includes the following steps:

[0048] S1, etching a plurality of arrayed top copper pads 1011 on the top copper foil layer 101 of the polymer double-sided copper clad substrate 1 and a plurality of bottom copper pads equal in number to the top copper pads 1011 and corresponding in position on the bottom copper foil layer 102, see Figure 1 and Figure 2each bottom copper pad and a corresponding top copper pad 1011 forms a copper pad group, and each column of the plurality of top copper pads 1011 arranged longitudinally forms a top copper pad column; a through hole 1041 is drilled through the top copper pad 1011 and the corresponding bottom copper pad at each copper pad group, as shown in Figure 3 and Figure 4 ; an alloy sheet 2 is welded between every two adjacent top copper pads 1011 in each top copper pad column, as shown in Figure 6 ;

[0049] S2, a plurality of hollow areas 301 corresponding to the number and position of the alloy sheets 2 are punched out on a polymer substrate with a size matching that of the polymer double-sided copper-clad substrate 1, to obtain a hollow frame 3, as shown in Figure 7 ; the hollow frame 3 is bonded to the top surface of the copper-clad substrate on which the alloy sheets 2 have been welded, wherein the frame 302 of each hollow area 301 surrounds the corresponding alloy sheet 2, as shown in Figure 8 ;

[0050] S3, a polymer top cover film 4 with a size matching that of the polymer double-sided copper-clad substrate 1 is covered on the hollow frame 3, and a packaged semi-finished substrate is obtained through hot pressing, as shown in Figure 9 , wherein the polymer top cover film 4 covers each hollow area 301 of the hollow frame 3;

[0051] S4, the frame lines of the hollow frame 3 except those at the edge positions are referred to as inner frame lines, each of which extends through opposite edges of the hollow frame 3, and a plurality of inner frame lines are arranged in a crisscross manner, as shown in Figure 10 ; the semi-finished substrate is cut along the cutting lines 5 corresponding to the positions of the inner frame lines, to obtain a plurality of surface-mounting fuses 6, wherein the two sub-bottom copper pads at the bottom of each surface-mounting fuse 6 serve as working pads, as shown in Figure 11 , wherein the frame line is the center line on the frame 302, and the frame line has the same extension direction as the corresponding frame.

[0052] This can realize the preparation of a plurality of surface-mounting fuses 6 at one time, and through the cooperation of the frame 302 of each hollow area 301 in the hollow frame 3 and the polymer top cover film 4, the alloy sheets 2 of each surface-mounting fuse 6 can be packaged simultaneously in the process of preparing a plurality of surface-mounting fuses 6, thereby simplifying the process and improving the production efficiency, and because the alloy sheets of the surface-mounting fuses are in a packaged state, an electric arc is less likely to occur in a large current scenario, thereby reducing the risk of fire. Moreover, because the flexible polymer double-sided copper-clad substrate 1 is used instead of the traditional hard ceramic substrate, the problem of the ceramic substrate being fragile and not shock-resistant can be solved, so that the surface-mounting fuses 6 prepared are shock-resistant and not fragile, and the surface-mounting fuses 6 will not bend and crack during use on a circuit board.

[0053] In one embodiment,

[0054] In step S1: the thickness of the polymer double-sided copper clad substrate 1 is less than 0.3 mm. The polymer double-sided copper clad substrate 1 also includes a polymer thin film layer 103. A top copper foil layer 101 is disposed on the top surface of the polymer thin film layer 103, and a bottom copper foil layer 102 is disposed on the bottom surface of the polymer thin film layer 103. The top copper foil layer 101, the polymer thin film layer 103 and the bottom copper foil layer 102 are formed by hot pressing together to form the polymer double-sided copper clad substrate 1.

[0055] In step S4: such as Figure 11 As shown, each surface mount fuse 6 includes a sub-polymer film layer 602. Two sub-bottom copper pads are distributed on the bottom surface and two sub-top copper pads are distributed on the top surface of the sub-polymer film layer 602. Each sub-top copper pad corresponds to the position of the corresponding sub-bottom copper pad and is electrically connected through an electrical via 1042. The two sub-top copper pads are electrically connected through an alloy sheet 2. The alloy sheet 2 is surrounded by the frame 302 of the corresponding cutout area 301. The cutout area 301 is covered by a sub-polymer top cover film 603, which encapsulates the alloy sheet 2.

[0056] Since the thickness of the polymer double-sided copper-clad substrate 1 is less than 0.3 mm, the thickness of the surface mount fuse 6 is significantly reduced.

[0057] In one preferred embodiment,

[0058] In step S1: the polymer film layer 103 is made of one of polyimide, polydimethyl terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer, preferably, the polymer film layer 103 is made of polyimide;

[0059] In step S2: the polymer substrate is made of one of polyimide, polydimethyl terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer, and the alloy sheet 2 is made of two or more metals selected from tin, silver, lead, indium, copper and bismuth.

[0060] In step S3: the polymer top cover film 4 is made of one of the following materials: polyimide, polydimethyl terephthalate, polytetrafluoroethylene, or ethylene-tetrafluoroethylene copolymer.

[0061] In one preferred embodiment, in step S1, when etching the top copper foil layer 101, first, top protective films are pasted on the areas of the top copper pads 1011 of the top copper foil layer 101 to form top copper foil protection areas, and the remaining areas of the top copper foil layer 101 form top copper foil non-protection areas, then the top copper foil non-protection areas are etched away to expose the polymer film layer 103, and a plurality of top copper pads 1011 arranged in a vertical and horizontal array are formed; when etching the bottom copper foil layer 102, first, bottom protective films are pasted on the areas of the bottom copper pads of the bottom copper foil layer 102 to form bottom copper foil protection areas, and the remaining areas of the bottom copper foil layer 102 form bottom copper foil non-protection areas, then the bottom copper foil non-protection areas are etched away to expose the polymer film layer 103, and a plurality of bottom copper pads are formed. Preferably, the process conditions for etching are: 3-5wt% H2SO4 acid pickling to remove oil, 80°C drying, 100-120°C pasting of photosensitive film, 6-8 / 21 class exposure, 50-60% development, and etching is completed.

[0062] In one preferred embodiment,

[0063] In step S1, each bottom copper pad is arranged symmetrically with the corresponding top copper pad 1011; the top copper pads 1011 at the edge of the top surface of the polymer film layer 103 are called edge top copper pads, and the remaining top copper pads 1011 are called inside top copper pads; the plurality of edge top copper pads are all in the shape of a cuboid and have the same size, the plurality of inside top copper pads are all in the shape of a cuboid and have the same size, the length of the edge top copper pad is half the length of the inside top copper pad, and the width and height of the edge top copper pad are the same as those of the inside top copper pad, wherein the length direction of the edge top copper pad and the inside top copper pad is the longitudinal direction, and the width direction of the edge top copper pad and the inside top copper pad is the transverse direction, see Figures 2-6 ; the shape and size of each alloy sheet 2 are adapted to the shape and size of the inside top copper pad, see Figure 6 .

[0064] In step S2, the shape of each hollow area 301 is adapted to the shape of the alloy sheet 2, the length of the frame 302 of the hollow area 301 is greater than the length of the alloy sheet 2, the width of the frame 302 of the hollow area 301 is greater than the width of the alloy sheet 2, the height of the frame 302 of the hollow area 301 is greater than the height of the alloy sheet 2, and the geometric center of each hollow area 301 coincides with the geometric center of the corresponding alloy sheet 2, see Figure 8 .

[0065] In this way, for each surface-mounted fuse 6, the frame 302 of the hollow area 301 does not touch the corresponding alloy sheet 2, and there is a gap between the frame 302 of the hollow area 301 and the corresponding alloy sheet 2, which is conducive to energy dissipation when the alloy sheet 2 is fused, and the alloy sheet 2 will not burst, and the alloy sheet 2 can be fused more completely.

[0066] wherein,

[0067] Step S1 is specifically: etching a plurality of top copper pads 1011 arranged in an array on the top copper foil layer 101 of the high polymer double-sided copper clad substrate 1 and etching a plurality of bottom copper pads corresponding in number and position to the top copper pads 1011 on the bottom copper foil layer 102, see Figure 1 and Figure 2 Each bottom copper pad and the corresponding top copper pad 1011 form a copper pad group; a plurality of through holes 1041 passing through the top copper pad 1011 and the corresponding bottom copper pad are drilled at each copper pad group, see Figure 3 and a layer of copper is electroplated on the inner wall of each through hole 1041 to obtain a plurality of electrical vias 1042, wherein each edge copper pad group formed by each edge top copper pad and the corresponding bottom copper pad is an edge copper pad group, each inner side copper pad group formed by each inner side top copper pad and the corresponding bottom copper pad is an inner side copper pad group, for each edge copper pad group, resin is buried in the remaining electrical vias 1042 on the edge copper pad group except for the electrical vias 1042 at the middle position of the edge line of each edge copper pad group, for each inner side copper pad group, resin is buried in the remaining electrical vias 1042 on the inner side copper pad group except for the electrical vias 1042 at the middle position of each inner side copper pad group, see Figure 4 ; a layer of nickel and tin is electroplated on each top copper pad 1011 to obtain a plurality of top metal pads 1012, and a layer of nickel and tin is electroplated on each bottom copper pad to obtain a plurality of bottom metal pads 1021 to enhance the welding capacity and electrical conductivity, see Figure 5 wherein a plurality of top metal pads 1012 arranged in each column are combined into a top metal pad column; a soldering sheet 2 is soldered between each two adjacent top metal pads 1012 in each top metal pad column using a reflow soldering process or a laser soldering process, see Figure 6 wherein each soldering sheet 2 is coated with an organic solvent layer;

[0068] In step S4, in combination with Figure 8 and Figure 10 each cutting line 5 arranged in the transverse direction is at the position of the electrical via 1042 in the middle of a plurality of corresponding top metal pads 1012, the two sub-bottom metal pads 601 at the bottom of each surface-mounted fuse 6 serve as working pads, and each working pad is electrically connected to the corresponding sub-top metal pad at the top through some electrical vias 1042, see Figure 11 .

[0069] For each edge copper pad group, the electrical through hole 1042 at the middle position of the edge line of each edge copper pad group is not resin-buried, for each inner side copper pad group, the electrical through hole 1042 at the middle position of each inner side copper pad group is not resin-buried, and each cutting line 5 arranged in the transverse direction is at the position of the electrical through hole 1042 in the middle of each corresponding top metal pad 1012, so that for each surface mount fuse 6, an electrical through hole 1042 in a cut state and not resin-buried is arranged between the edge of each working pad and the edge of the corresponding top metal pad, and thus when the working pad of the surface mount fuse 6 is welded to the copper foil on the circuit board, the solder paste used for welding can flow into the electrical through hole 1042 in the cut state, so as to improve the flatness of the welding.

[0070] Since each group of copper pad groups is provided with a plurality of electrical through holes 1042, the current passing capacity can be increased, and since each alloy sheet 2 is coated with an organic solvent layer, the alloy sheet 2 can be prevented from being not completely fused and adhered after being fused.

[0071] Preferably, in step S1, the size of the aperture of each through hole 1041 is set according to the overcurrent specification of the surface mount fuse 6 prepared in step S4. Preferably, the aperture of the through hole 1041 is greater than 0.2mm.

[0072] In one embodiment,

[0073] Step S3 is specifically: covering a high polymer top cover film 4 coated with an adhesive and matching the size of the high polymer double-sided copper clad substrate 1 on the hollow frame 3, and obtaining the packaged semi-finished product substrate by vacuum hot pressing, wherein the high polymer top cover film 4 covers each hollow area 301 of the hollow frame 3.

[0074] The vacuum hot pressing is specifically hot pressing in a vacuum hot pressing machine, specifically: first setting the vacuum condition to 0.5-0.8Mpa, then keeping for 10min under the hot pressing pressure of 220Psi and the hot pressing temperature of 160℃, then keeping for 120min under the hot pressing pressure of 280Psi and the hot pressing temperature of 170℃, and finally keeping for 30min under the cold pressing pressure of 100Psi and the cold pressing temperature of 30℃, and the pressing is completed.

[0075] As Figure 11As shown, a surface mount fuse is prepared and packaged by using the above-mentioned surface mount fuse packaging method, comprising a sub-high polymer film layer 602, two sub-bottom copper pads are distributed at the bottom surface of the sub-high polymer film layer 602, and two sub-top copper pads are distributed at the top surface, each sub-top copper pad corresponds to the position of the corresponding sub-bottom copper pad and is electrically connected through an electrical via hole 1042, the two sub-top copper pads are electrically connected through an alloy sheet 2, the alloy sheet 2 is surrounded by the frame 302 of the corresponding hollow area 301, the hollow area 301 is covered by a sub-high polymer top cover film 603, and the frame 302 of the hollow area 301, the sub-high polymer top cover film 603 and the sub-high polymer film layer 602 cooperate to form an encapsulating shell of the alloy sheet 2.

[0076] The present application can realize the preparation and packaging of multiple surface mount fuses 6 at one time, thereby simplifying the process and improving the production efficiency. By using a one-time punching forming process, the polymer substrate is hollowed out and placed on the top surface of the copper-clad substrate with the welded alloy sheet 2 to form a sealed packaging structure, replacing the injection molding process of the traditional ceramic substrate fuse process, greatly improving the production efficiency. For each surface mount fuse 6, the alloy sheet 2 is fully encapsulated by the sub-high polymer film layer 602, the frame 302 of the hollow area 301 and the sub-high polymer top cover film 603, so that the alloy sheet 2 is completely isolated from the external environment, thereby avoiding the influence of the external environment, having the effects of prolonging the service life, explosion-proof and arc-proof. The high polymer film layer 103, the polymer substrate and the polymer top cover film 4 used in the present application are flexible, so that the surface mount fuse 6 prepared will not crack during use, and the problem of fragile ceramic substrate fuse can be solved.

[0077] In summary, the surface mount fuse 6 prepared by the present application has flexibility, thin thickness, shock resistance, and is suitable for high-current working scenarios.

[0078] The above is only the preferred embodiment of the present application, and it should be noted that for ordinary skilled persons in the technical field, several improvements and replacements can be made without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing and packaging a surface-mount fuse, characterized in that, Includes the following steps: S1. A plurality of top copper pads (1011) are etched on the top copper foil layer (101) of the polymer double-sided copper clad substrate (1), and a plurality of bottom copper pads are etched on the bottom copper foil layer (102) in the same number and corresponding positions as the top copper pads (1011). Each bottom copper pad and the corresponding top copper pad (1011) form a copper pad group. A plurality of top copper pads (1011) arranged in each column form a top copper pad column. Through holes (1041) are drilled through the top copper pads (1011) and the bottom copper pads at each copper pad group. An alloy sheet (2) is welded between every two adjacent top copper pads (1011) in each top copper pad column. S2. A plurality of hollow areas (301) are punched out on a polymer substrate, which are equal in number and corresponding in position to the alloy sheet (2) to obtain a hollow frame (3); the hollow frame (3) is bonded to the top surface of the copper-clad substrate of the welded alloy sheet (2), wherein the border (302) of each hollow area (301) surrounds the corresponding alloy sheet (2). S3. A polymer top cover film (4) is placed on the hollow frame (3) and the encapsulated semi-finished substrate is obtained by hot pressing, wherein the polymer top cover film (4) covers each hollow area (301) of the hollow frame (3); S4. The frame lines of the hollow frame (3) except for the edge positions are called inner frame lines. Each inner frame line runs through the two opposite edges of the hollow frame (3) and multiple inner frame lines are arranged in a crisscross pattern. The semi-finished substrate is cut along the cutting line (5) corresponding to the position of each inner frame line to obtain multiple surface mount fuses (6). The two bottom copper pads of each surface mount fuse (6) are used as working pads. The frame line is the center line on the frame (302) and the extension direction of the frame line is the same as that of the corresponding frame.

2. The method for preparing and packaging a surface-mount fuse according to claim 1, characterized in that, In step S1: the polymer double-sided copper-clad substrate (1) further includes a polymer thin film layer (103), the top copper foil layer (101) is disposed on the top surface of the polymer thin film layer (103), and the bottom copper foil layer (102) is disposed on the bottom surface of the polymer thin film layer (103); In step S4: Each surface mount fuse (6) includes a sub-polymer film layer (602). The sub-polymer film layer (602) has two sub-bottom copper pads distributed on its bottom surface and two sub-top copper pads distributed on its top surface. Each sub-top copper pad corresponds to the position of the corresponding sub-bottom copper pad and is electrically connected through an electrical via (1042). The two sub-top copper pads are electrically connected through an alloy sheet (2). The alloy sheet (2) is surrounded by the frame (302) of the corresponding cutout area (301). The cutout area (301) is covered by a sub-polymer top cover film (603) to encapsulate the alloy sheet (2).

3. The method for preparing and packaging a surface-mount fuse according to claim 2, characterized in that, In step S1: the polymer film layer (103) is made of one of polyimide, polydimethyl terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer; In step S2: the polymer substrate is made of one of polyimide, polydimethyl terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer, and the alloy sheet (2) is made of two or more metals selected from tin, silver, lead, indium, copper and bismuth. In step S3: the polymer top cover film (4) is made of one of polyimide, polydimethyl terephthalate, polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer.

4. The method for preparing and packaging a surface-mount fuse according to claim 2, characterized in that, In step S1: When etching the top copper foil layer (101), a top protective film is first applied to each top copper pad (1011) area of ​​the top copper foil layer (101) to form a top copper foil protected area, and the remaining areas of the top copper foil layer (101) form a top copper foil unprotected area. Then, the top copper foil unprotected area is etched away, and the polymer film layer (103) is exposed, forming a plurality of top copper pads (1011) arranged in a longitudinal and transverse array. When etching the bottom copper foil layer (102), a bottom protective film is first applied to each bottom copper pad area of ​​the bottom copper foil layer (102) to form a bottom copper foil protected area, and the remaining areas of the bottom copper foil layer (102) form a bottom copper foil unprotected area. Then, the bottom copper foil unprotected area is etched away, and the polymer film layer (103) is exposed, forming a plurality of bottom copper pads.

5. The method for preparing and packaging a surface-mount fuse according to claim 2, characterized in that, In step S1: each bottom copper pad and the corresponding top copper pad (1011) are arranged symmetrically up and down; the top copper pad (1011) located at the edge of the top surface of the polymer film layer (103) is called the edge top copper pad, and the remaining top copper pads (1011) are called the inner top copper pads. The multiple edge top copper pads are all cuboid in shape and have the same size. The multiple inner top copper pads are all cuboid in shape and have the same size. The length of the edge top copper pad is half the length of the inner top copper pad. The width and height of the edge top copper pad and the inner top copper pad are the same. The length direction of the edge top copper pad and the inner top copper pad is the longitudinal direction, and the width direction of the edge top copper pad and the inner top copper pad is the transverse direction. The shape and size of each alloy sheet (2) are adapted to the shape and size of the inner top copper pad.

6. The method for preparing and packaging a surface-mount fuse according to claim 5, characterized in that, In step S2: the shape of each of the hollow areas (301) is adapted to the shape of the alloy sheet (2), the length of the border (302) of the hollow area (301) is greater than the length of the alloy sheet (2), the width of the border (302) of the hollow area (301) is greater than the width of the alloy sheet (2), the height of the border (302) of the hollow area (301) is greater than the height of the alloy sheet (2), and the geometric center position of each hollow area (301) coincides with the geometric center position of the corresponding alloy sheet (2).

7. The method for preparing and packaging a surface-mount fuse according to claim 5, characterized in that, Step S1 specifically involves etching multiple arrayed top copper pads (1011) on the top copper foil layer (101) of the polymer double-sided copper-clad substrate (1) and etching multiple bottom copper pads on the bottom copper foil layer (102) in the same number and corresponding positions as the top copper pads (1011). Each bottom copper pad and its corresponding top copper pad (1011) form a copper pad group. Multiple through-holes are drilled at each copper pad group, connecting the top copper pad (1011) and its corresponding bottom copper pad (1011). Through holes (1041) are formed in the bottom copper pads, and a layer of copper is electroplated on the inner wall of each through hole (1041) to obtain multiple electrical vias (1042). Each edge top copper pad and its corresponding bottom copper pad form an edge copper pad group, and each inner top copper pad and its corresponding bottom copper pad form an inner copper pad group. For each edge copper pad group, except for those located at the middle of the edge line of each edge copper pad group... In addition to the electrical vias (1042), the remaining electrical vias (1042) on each of the edge copper pad groups are treated with resin buried vias. For each of the inner copper pad groups, except for the electrical vias (1042) located in the middle of each of the inner copper pad groups, the remaining electrical vias (1042) on each of the inner copper pad groups are treated with resin buried vias. A layer of nickel and tin is electroplated on each of the top copper pads (1011) to obtain a plurality of top metal pads (1012), and a layer of nickel and tin is electroplated on each of the bottom copper pads to obtain a plurality of bottom metal pads (1021). The plurality of top metal pads (1012) arranged in each column longitudinally are combined to form a top metal pad column. An alloy sheet (2) is welded between each two adjacent top metal pads (1012) in each of the top metal pad columns using a reflow soldering process or a laser soldering process. Each alloy sheet (2) is coated with an organic flux layer. In step S4: each of the transversely arranged cutting lines (5) is located at the position of the electrical via (1042) in the middle of a plurality of corresponding top metal pads (1012), and the two bottom sub-bottom metal pads (601) in each of the surface mount fuses (6) serve as working pads, and each working pad is electrically connected to the corresponding top sub-top metal pad through a partial electrical via (1042).

8. The method for preparing and packaging a surface-mount fuse according to claim 7, characterized in that, In step S1: The diameter of each through hole (1041) is set according to the overcurrent specification of the surface mount fuse (6) obtained in step S4.

9. The method for preparing and packaging a surface-mount fuse according to claim 1, characterized in that, Step S3 specifically involves covering the hollow frame (3) with a polymer top cover film (4) coated with adhesive and adapted to the size of the polymer double-sided copper clad substrate (1), and obtaining the encapsulated semi-finished substrate by vacuum hot pressing, wherein the polymer top cover film (4) covers each hollow area (301) of the hollow frame (3).

10. A surface mount fuse, manufactured and packaged using the method for manufacturing and packaging a surface mount fuse as described in any one of claims 2-8, characterized in that: The system includes a sub-polymer film layer (602), on which two sub-bottom copper pads are distributed at the bottom surface and two sub-top copper pads are distributed at the top surface. Each sub-top copper pad corresponds to the corresponding sub-bottom copper pad and is electrically connected through an electrical via (1042). The two sub-top copper pads are electrically connected through an alloy sheet (2). The alloy sheet (2) is surrounded by the frame (302) of the corresponding hollow area (301). The hollow area (301) is covered by a sub-polymer top cover film (603). The frame (302) of the hollow area (301), the sub-polymer top cover film (603) and the sub-polymer film layer (602) cooperate to form the encapsulation shell of the alloy sheet (2).

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