Full-encapsulation PTC surface-mounted device encapsulation method and full-encapsulation PTC surface-mounted device

Abstract

The invention discloses a packaging method for a fully-packaged PTC surface-mounted device and the fully-packaged PTC surface-mounted device, and the packaging method comprises the steps: etching a plurality of top copper bonding pads and bottom copper bonding pads on a double-sided copper-clad substrate, and enabling each bottom copper bonding pad and the corresponding top copper bonding pad to form a copper bonding pad group; drilling a via hole at each copper bonding pad group; a surface mounting PTC device is welded between every two adjacent top copper bonding pads which are longitudinally arranged; bonding a positioning frame at the periphery of the top surface of the double-sided copper-clad substrate; pouring an encapsulating material into the positioning frame, and fully encapsulating each surface-mounted PTC device after leveling and curing to obtain a whole-board packaged surface-mounted PTC device; and cutting up the whole-board packaging surface mounting PTC device to obtain a plurality of full-packaging PTC surface mounting devices. According to the invention, full encapsulation of a plurality of surface-mounted PTC devices can be realized at one time, thermal expansion of the surface-mounted PTC devices can be limited, and the service life of the full-encapsulated PTC surface-mounted devices can be prolonged.

Description

Technical Field

[0001] This invention belongs to the field of surface mount technology, specifically relating to a fully encapsulated PTC surface mount device packaging method and a fully encapsulated PTC surface mount device. Background Technology

[0002] Currently, the demand for electronic devices is increasing, and the operating environment of electronic devices is becoming more and more stringent. This necessitates further enhancing the structural stability of surface mount electronic devices in order to extend their service life.

[0003] To reduce the impact of the external environment on surface-mount PTC devices and slow down the oxidation and aging process of the internal materials of surface-mount PTC devices, some manufacturers have launched surface-mount PTC devices with four-sided adhesive coating. Although this design can isolate the intrusion of moisture and oxygen in the external environment to a certain extent, the thermal expansion problem of the surface-mount PTC device itself will inevitably lead to a gradual shortening of its service life. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the present invention provides a fully encapsulated PTC surface mount device packaging method and a fully encapsulated PTC surface mount device, which can realize the full encapsulation of multiple surface mount PTC devices at one time, and can limit the thermal expansion of the surface mount PTC devices themselves, thereby extending the service life of the obtained fully encapsulated PTC surface mount devices.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A fully encapsulated PTC surface mount device packaging method includes the following steps:

[0007] S1. A plurality of arrayed top copper pads are etched on the top copper foil layer of the double-sided copper-clad substrate, and a plurality of bottom copper pads of the same number and corresponding position as the top copper pads are etched on the bottom copper foil layer. Each bottom copper pad and the corresponding top copper pad form a copper pad group. Through holes are drilled through the top copper pads and bottom copper pads at each copper pad group. A surface mount PTC device is soldered between every two vertically arranged adjacent top copper pads, wherein two adjacent top copper pads are respectively soldered to the two bottom pads of the corresponding surface mount PTC device.

[0008] S2. A closed positioning frame is attached to the top surface of the double-sided copper-clad substrate around the perimeter, and the positioning frame surrounds the PTC devices mounted on each surface and the top copper pads.

[0009] S3. Pour the encapsulation material into the positioning frame, and after leveling and curing, fully encapsulate each of the surface mount PTC devices to obtain a full board packaged surface mount PTC devices.

[0010] S4. According to the position of each bottom copper pad on the bottom of the full-board packaged surface mount PTC device, the full-board packaged surface mount PTC device is cut to obtain multiple fully encapsulated PTC surface mount devices. Each fully encapsulated PTC surface mount device includes a surface mount PTC device and has two sub-bottom copper pads on the bottom as working pads.

[0011] Furthermore,

[0012] In step S1: the double-sided copper-clad substrate further includes a substrate body layer, the top copper foil layer is disposed on the top surface of the substrate body layer, and the bottom copper foil layer is disposed on the bottom surface of the substrate body layer;

[0013] In step S4: After the entire board of surface mount PTC devices is cut, the substrate body layer is divided into multiple sub-substrate body layers. Each sub-substrate body layer has two sub-bottom copper pads distributed on its bottom surface, which serve as the working pads for the corresponding fully encapsulated PTC surface mount devices. Each sub-substrate body layer has two sub-top copper pads distributed on its top surface, which are used to solder to the two bottom pads of the corresponding surface mount PTC devices. The two top pads of the surface mount PTC devices are then encapsulated by the cured encapsulation material.

[0014] Furthermore,

[0015] Step S1 specifically involves: etching multiple arrayed top copper pads on the top copper foil layer of the double-sided copper-clad substrate, and etching multiple bottom copper pads on the bottom copper foil layer, the number of which is equal to and the positions of the top copper pads are corresponding. Each bottom copper pad and its corresponding top copper pad form a copper pad group. Multiple through-holes are drilled through each copper pad group, penetrating the top copper pads and the corresponding bottom copper pads. A layer of copper is electroplated on the inner wall of each through-hole to obtain multiple electrical vias. Each electrical via is then subjected to resin buried via treatment. To seal each of the electrical vias; to electroplate a layer of nickel and tin onto each of the top copper pads to obtain multiple top metal pads, and to electroplate a layer of nickel and tin onto each of the bottom copper pads to obtain multiple bottom metal pads; to print solder paste onto each of the top metal pads using a screen printing process, to mount a surface mount PTC device between every two vertically arranged adjacent top metal pads, and to pass through a reflow oven so that the two adjacent top metal pads are respectively soldered to the two bottom pads of the corresponding surface mount PTC device;

[0016] In step S4: Each of the fully encapsulated PTC surface mount devices has two sub-bottom metal pads on its bottom, which serve as working pads.

[0017] Further, step S3 specifically involves: pouring the encapsulation material into the positioning frame, and after leveling, fully encapsulating each of the surface mount PTC devices; placing the double-sided copper-clad substrate bonded to the positioning frame into an oven; and heating the encapsulation material to cure it. The cured encapsulation material forms an encapsulation shell, which, together with the double-sided copper-clad substrate, fully encapsulates each surface mount PTC device, resulting in a complete board package of surface mount PTC devices.

[0018] Furthermore,

[0019] In step S1: the substrate body layer is made of one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide;

[0020] In step S2: the positioning frame is made of one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide;

[0021] In step S3: the encapsulating material is a thermosetting resin.

[0022] Further, in step S3: the encapsulating material is selected from one or more of epoxy resin, phenolic resin, and unsaturated polyester.

[0023] Further, in step S1: each of the bottom copper pads and the corresponding top copper pads are arranged symmetrically vertically; the spacing between two adjacent surface mount PTC devices arranged horizontally is equal to the spacing between two adjacent surface mount PTC devices arranged vertically.

[0024] Further, in step S1: the surface mount PTC device includes a PTC conductive polymer layer; or, the surface mount PTC device includes multiple PTC conductive polymer layers in parallel.

[0025] A fully encapsulated PTC surface mount device is packaged using the aforementioned fully encapsulated PTC surface mount device packaging method. It includes a sub-substrate body layer. 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-substrate body layer. Each sub-top copper pad corresponds to a corresponding sub-bottom copper pad and is electrically connected via an electrical via. A surface mount PTC device is soldered between the two sub-top copper pads. The two sub-top copper pads are respectively soldered to the two bottom pads of the surface mount PTC device. The top surface and sides of the surface mount PTC device are encapsulated by an encapsulation shell. The bottom surface of the surface mount PTC device is encapsulated by the sub-substrate body layer. The two sub-bottom copper pads serve as the working pads of the fully encapsulated PTC surface mount device.

[0026] Furthermore, the two top pads of the surface mount PTC device are arranged symmetrically from left to right, and each top pad of the surface mount PTC device is arranged symmetrically from top to bottom with the corresponding bottom pad. The encapsulation shell is formed by the cured encapsulation material.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The fully encapsulated PTC surface mount device packaging method of the present invention includes the following steps: S1, etching multiple arrayed top copper pads on the top copper foil layer of a double-sided copper-clad substrate and etching multiple bottom copper pads on the bottom copper foil layer, the number of which is equal to and the positions of the top copper pads, each bottom copper pad forming a copper pad group with the corresponding top copper pad; drilling through-holes through the top copper pads and bottom copper pads at each copper pad group; soldering a surface mount PTC device between every two vertically arranged adjacent top copper pads, wherein two adjacent top copper pads are respectively soldered to the two bottom pads of the corresponding surface mount PTC device; S2, encapsulating... A closed positioning frame is bonded to the top circumference of the double-sided copper-clad substrate, surrounding each surface-mount PTC device and each top copper pad; S3, the encapsulation material is poured into the positioning frame, and after leveling and curing, each surface-mount PTC device is fully encapsulated to obtain a full-board packaged surface-mount PTC device; S4, according to the position of each bottom copper pad at the bottom of the full-board packaged surface-mount PTC device, the full-board packaged surface-mount PTC device is cut to obtain multiple fully encapsulated PTC surface-mount devices. Each fully encapsulated PTC surface-mount device includes one surface-mount PTC device and has two sub-bottom copper pads at the bottom as working pads. This method enables the complete encapsulation of multiple surface-mount PTC devices in a single operation. Using a double-sided copper-clad substrate as the base effectively prevents the encapsulation material from adhering to the bottom pads of the PTC devices, thus avoiding mis-encapsulation and soldering defects. The positioning frame further prevents the encapsulation material from overflowing and flowing onto the bottom copper pads of the double-sided copper-clad substrate, preventing mis-encapsulation and ensuring that the soldering performance of the sub-bottom copper pads of the fully encapsulated PTC surface-mount devices remains unaffected. Furthermore, the double-sided copper-clad substrate and the flow... The combination of the encapsulating material after leveling and curing allows the surface-mount PTC device inside the fully encapsulated PTC surface mount device to be completely isolated from the external environment, thus avoiding the influence of the external environment. In addition, the double-sided copper-clad substrate and the dense and hard encapsulating material after leveling and curing can limit the thermal expansion of the fully encapsulated PTC surface mount device, thereby improving the holding time of the fully encapsulated PTC surface mount device under high current conditions. This allows the fully encapsulated PTC surface mount device to be used in more severe environments, thus extending the service life of the fully encapsulated PTC surface mount device. Attached Figure Description

[0029] Figure 1 This is a three-dimensional structural diagram of the double-sided copper-clad substrate in this invention;

[0030] Figure 2 In order to be in Figure 1 A top view of a double-sided copper-clad substrate with top copper pads etched on the top copper foil layer and bottom copper pads etched on the bottom copper foil layer.

[0031] Figure 3 In order to be in Figure 2 A top view of the structure after drilling through holes at each copper pad group;

[0032] Figure 4 In order to be in Figure 3 A top view of the structure after each through hole is electroplated with a layer of copper and resin buried through hole treatment.

[0033] Figure 5 In order to be in Figure 4 A schematic diagram of the three-dimensional structure after electroplating a layer of nickel and a layer of tin onto the top and bottom copper pads, respectively;

[0034] Figure 6 In order to be in Figure 5 A three-dimensional structural diagram showing the structure after a surface-mount PTC device is soldered between every two vertically arranged adjacent top copper pads.

[0035] Figure 7 This is a schematic diagram of the three-dimensional structure of the positioning frame;

[0036] Figure 8 To be Figure 7 The positioning frame in the middle is glued to Figure 6 A three-dimensional structural diagram of the top surface of a double-sided copper-clad substrate.

[0037] Figure 9 To pour the encapsulation material into Figure 8 A schematic diagram of the three-dimensional structure within the positioning frame and after the encapsulating material has been leveled;

[0038] Figure 10 for Figure 9 A schematic diagram of the cutting lines on the surface mount PTC device of the whole board after the encapsulation material has been cured;

[0039] Figure 11 A three-dimensional structural diagram of one of the fully encapsulated PTC surface mount devices obtained after dicing a full board of packaged PTC devices;

[0040] Figure 12 for Figure 11 A schematic diagram of the reverse structure;

[0041] Figure 13 for Figure 12A cross-sectional view along direction A of a fully encapsulated PTC surface mount device, where the surface mount PTC device includes a PTC conductive polymer layer.

[0042] Figure 14 for Figure 13 A schematic diagram of the reverse structure;

[0043] Figure 15 for Figure 12 A cross-sectional view along direction A of a fully encapsulated PTC surface mount device, which includes two layers of PTC conductive polymer.

[0044] Figure 16 for Figure 15 A schematic diagram of the reverse structure;

[0045] Figure 17 for Figure 12 A cross-sectional view along direction A of a fully encapsulated PTC surface mount device, which includes three layers of PTC conductive polymer.

[0046] Figure 18 for Figure 17 A schematic diagram of the reverse structure.

[0047] Figure reference numerals: 1. 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. Substrate body layer; 1041. Via; 1042. Electrical via; 2. Positioning frame; 301. Encapsulation material; 302. Encapsulation shell; 4. Scribing line; 5. Fully encapsulated PTC surface mount device; 501. Surface mount PTC. Device, 50101, bottom pad, 50102, top pad, 50103, PTC conductive polymer layer, 50104, top copper electrode layer, 50105, bottom copper electrode layer, 50106, top insulating layer, 50107, bottom insulating layer, 50108, left conductive via, 50109, right conductive via, 50110, middle insulating layer, 502, sub-bottom copper pad, 503, sub-substrate body layer, 504, sub-top copper pad. Detailed Implementation

[0048] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0052] A fully encapsulated PTC surface mount device packaging method includes the following steps:

[0053] S1, such as Figure 1 and Figure 2 As shown, multiple arrayed top copper pads 1011 are etched on the top copper foil layer 101 of the double-sided copper-clad substrate 1, and multiple bottom copper pads of the same number and corresponding positions as the top copper pads 1011 are etched on the bottom copper foil layer 102. Each bottom copper pad and its corresponding top copper pad 1011 form a copper pad group; through-holes 1041 are drilled at each copper pad group, penetrating the top copper pads 1011 and the bottom copper pads. Figure 3 ;like Figure 6 As shown, a surface mount PTC device 501 is soldered between every two vertically arranged adjacent top copper pads 1011, wherein two adjacent top copper pads 1011 are respectively soldered to the two bottom pads 50101 of the corresponding surface mount PTC device 501, and there is a certain distance between two adjacent surface mount PTC devices 501 to facilitate subsequent dicing.

[0054] S2, such as Figure 7 and Figure 8 As shown, the closed positioning frame 2 is bonded to the top surface of the double-sided copper-clad substrate 1 around the perimeter. The positioning frame 2 surrounds the PTC devices 501 mounted on each surface and the top copper pads 1011.

[0055] S3, such as Figure 9 and Figure 10 As shown, the encapsulation material 301 is poured into the positioning frame 2. After leveling and curing, the surface mount PTC devices 501 are fully encapsulated to obtain a full board package of surface mount PTC devices.

[0056] S4, such as Figure 10 As shown, based on the positions of the bottom copper pads of the surface-mount PTC devices in the full-board package, the surface-mount PTC devices are diced to obtain multiple fully encapsulated PTC surface-mount devices 5. Each fully encapsulated PTC surface-mount device 5 includes a surface-mount PTC device 501 and has two sub-bottom copper pads 502 at the bottom, which serve as working pads. Figures 11-18 The cutting lines used when dicing surface-mount PTC devices on a full-board package are shown in [reference needed]. Figure 10 Figure 4 in the figure, where Figure 11 The fully encapsulated PTC surface mount device 5 is located inside the surface mount PTC device in the whole board package.

[0057] This allows for the complete encapsulation of multiple surface-mount PTC devices 501 in a single operation. Using the double-sided copper-clad substrate 1 as the base, it effectively prevents the encapsulation material 301 from adhering to the bottom pads 50101 of the surface-mount PTC devices 501, thus avoiding mis-encapsulation of the bottom pads 50101 and resulting in poor soldering. Furthermore, the positioning frame 2 positions the encapsulation material 301, preventing it from overflowing and flowing onto the bottom copper pads of the double-sided copper-clad substrate 1. This further prevents mis-encapsulation of the bottom copper pads of the double-sided copper-clad substrate 1, ensuring that the soldering performance of the sub-bottom copper pads 502 of the fully encapsulated PTC surface-mount devices 5 is not affected. By combining the double-sided copper-clad substrate 1 and the leveled and cured encapsulation material 301, the surface-mount PTC device 501 inside the fully encapsulated PTC surface mount device 5 can be completely isolated from the external environment, thus avoiding the influence of the external environment. In addition, the double-sided copper-clad substrate 1 and the leveled and cured encapsulation material 301 are dense and hard, which can limit the thermal expansion of the fully encapsulated PTC surface mount device 5, thereby improving the holding time of the fully encapsulated PTC surface mount device 5 under high current conditions. This allows the fully encapsulated PTC surface mount device 5 to be used in more severe environments, and extends the service life of the fully encapsulated PTC surface mount device 5.

[0058] in,

[0059] In step S1: such as Figure 1As shown, the double-sided copper-clad substrate 1 also includes a substrate body layer 103, a top copper foil layer 101 disposed on the top surface of the substrate body layer 103, and a bottom copper foil layer 102 disposed on the bottom surface of the substrate body layer 103. The top copper foil layer 101, the substrate body layer 103 and the bottom copper foil layer 102 are formed by hot pressing to form the double-sided copper-clad substrate 1.

[0060] In step S4: After dicing the entire board for surface mount PTC devices, the substrate body layer 103 is divided into multiple sub-substrate body layers 503. Each sub-substrate body layer 503 has two sub-bottom copper pads 502 distributed on its bottom surface, serving as the working pads for the corresponding fully encapsulated PTC surface mount device 5. Each sub-substrate body layer 503 has two sub-top copper pads 504 distributed on its top surface, used for soldering to the two bottom pads 50101 of the corresponding surface mount PTC device 501. The two top pads 50102 of the surface mount PTC device 501 are then encapsulated by the cured encapsulation material 301. (See...) Figures 11-18 .

[0061] In one implementation,

[0062] Step S1 specifically involves etching a plurality of arrayed top copper pads 1011 on the top copper foil layer 101 of the double-sided copper-clad substrate 1, and etching a plurality of bottom copper pads on the bottom copper foil layer 102 in an equal number and corresponding positions to the top copper pads 1011. Each bottom copper pad and its corresponding top copper pad 1011 form a copper pad group, as shown in [reference needed]. Figure 2 Drill multiple through holes 1041 at each copper pad group, connecting the top copper pad 1011 and the corresponding bottom copper pad, as shown in the figure. Figure 3 A layer of copper is electroplated on the inner wall of each via 1041 to obtain multiple electrical vias 1042. Each electrical via 1042 is then sealed with resin vias. (See attached image.) Figure 4 A layer of nickel and tin is electroplated onto each top copper pad 1011 to obtain multiple top metal pads 1012, and a layer of nickel and tin is electroplated onto each bottom copper pad to obtain multiple bottom metal pads 1021, see [link to documentation]. Figure 5 To improve the soldering capability and conductivity of the top metal pads 1012 and bottom metal pads 1021; solder paste is printed on each top metal pad 1012 using a screen printing process, preferably with a solder paste thickness controlled between 0.02-0.08 mm; a surface mount PTC device 501 is mounted between every two longitudinally arranged adjacent top metal pads 1012, and the device passes through a reflow oven so that adjacent top metal pads 1012 are respectively soldered to the two bottom pads 50101 of the corresponding surface mount PTC device 501. See Figure 6 ;

[0063] In step S4: Each fully encapsulated PTC surface mount device 5 has two sub-bottom metal pads 502 on its bottom, which serve as working pads, see... Figures 11-18 .

[0064] In one implementation, step S3 specifically involves: [e.g., ...] Figure 9 As shown, the encapsulation material 301 is poured into the positioning frame 2. After leveling, the surface-mount PTC devices 501 are completely wrapped. The double-sided copper-clad substrate 1, which is bonded to the positioning frame 2, is placed on the platform inside the oven. The encapsulation material 301 is accelerated to cure by heating. The cured encapsulation material 301 forms the encapsulation shell 302. Figure 10 The encapsulation shell 302, together with the double-sided copper-clad substrate 1, fully encapsulates each surface-mount PTC device 501, resulting in a full-board package of surface-mount PTC devices.

[0065] The platform inside the oven is equipped with a level to ensure that the double-sided copper-clad substrate 1 is in a horizontal state and to ensure that the encapsulation material 301 is in a horizontal state, thereby ensuring the uniformity of the thickness of the fully encapsulated PTC surface mount device 5.

[0066] In one implementation,

[0067] In step S1: the substrate body layer 103 is made of one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide.

[0068] In step S2: the material of the positioning frame 2 is one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide;

[0069] In step S3: the encapsulating material 301 is made of thermosetting resin; preferably, the encapsulating material 301 is selected from one or more of epoxy resin, phenolic resin, and unsaturated polyester.

[0070] The height of the positioning frame 2 determines the amount of potting compound, i.e. the amount of encapsulating material 301, and the curing thickness, and ultimately determines the thickness of the fully encapsulated PTC surface mount device 5. Preferably, the height of the positioning frame 2 is controlled between 0.8 and 1.2 mm.

[0071] In one implementation,

[0072] In step S1: Each bottom copper pad and its corresponding top copper pad 1011 are arranged symmetrically vertically; the spacing between two adjacent surface mount PTC devices 501 arranged horizontally is equal to the spacing between two adjacent surface mount PTC devices 501 arranged vertically, see... Figure 6 and Figure 8 Preferably, the spacing between two adjacent surface-mount PTC devices 501 arranged laterally is controlled to be 0.3-0.6 mm.

[0073] In step S4: the thickness of the slicing blade used for slicing is controlled at 0.1-0.2mm.

[0074] In one implementation, in step S1:

[0075] like Figure 13 and Figure 14 As shown, the surface mount PTC device 501 includes a PTC conductive polymer layer 50103. A top copper electrode layer 50104 is located on the right side of the top surface of the PTC conductive polymer layer 50103, and a bottom copper electrode layer 50105 is located on the left side of the bottom surface. A top insulating layer 50106 is located on the top surface of the top copper electrode layer 50104, and the top insulating layer 50106 is in direct contact with the left side of the top surface of the PTC conductive polymer layer 50103. A bottom insulating layer 50107 is located on the bottom surface of the bottom copper electrode layer 50105, and the bottom insulating layer 50107 is in direct contact with the right side of the bottom surface of the PTC conductive polymer layer 50103. Top pads 5010 are located on the left and right sides of the top surface of the top insulating layer 50106, respectively. 2. Bottom pads 50101 are provided on the left and right sides of the bottom surface of the bottom insulating layer 50107. The top pad 50102 on the left side is electrically connected to the bottom pad 50101 through a left conductive via 50108 located on the left side of the PTC conductive polymer layer 50103. The top pad 50102 on the right side is electrically connected to the bottom pad 50101 through a right conductive via 50109 located on the right side of the PTC conductive polymer layer 50103. The left conductive via 50108 is spaced a certain distance from the top copper electrode layer 50104 and is in direct contact with the bottom copper electrode layer 50105. The right conductive via 50109 is in direct contact with the top copper electrode layer 50104 and is spaced a certain distance from the bottom copper electrode layer 50105.

[0076] Or, such as Figure 15 and Figure 16As shown, the surface mount PTC device 501 includes two PTC conductive polymer layers 50103 in parallel. The upper PTC conductive polymer layer 50103 has a top copper electrode layer 50104 on the left side of its top surface and a bottom copper electrode layer 50105 on the right side of its bottom surface. The lower PTC conductive polymer layer 50103 also has a top copper electrode layer 50104 on the right side of its top surface and a bottom copper electrode layer 50105 on the left side of its bottom surface. An intermediate insulating layer 50110 is provided between the bottom copper electrode layer 50105 on the bottom surface of the upper PTC conductive polymer layer 50103 and the top copper electrode layer 50104 on the top surface of the lower PTC conductive polymer layer 50103. Layer 50110 is in direct contact with the bottom left portion of the upper PTC conductive polymer layer 50103 and the top left portion of the lower PTC conductive polymer layer 50103. A top insulating layer 50106 is provided on the top surface of the upper top copper electrode layer 50104, and the top insulating layer 50106 is in direct contact with the top right portion of the upper PTC conductive polymer layer 50103. A bottom insulating layer 50107 is provided on the bottom surface of the lower bottom copper electrode layer 50105, and the bottom insulating layer 50107 is in direct contact with the bottom right portion of the lower PTC conductive polymer layer 50103. Top pads 50102 are provided on the left and right portions of the top surface of the top insulating layer 50106, respectively. The bottom surface of the bottom insulating layer 50107... Bottom pads 50101 are provided on the left and right sides respectively. The top pad 50102 on the left side is electrically connected to the bottom pad 50101 through a left conductive via 50108 located on the left side of each PTC conductive polymer layer 50103. The top pad 50102 on the right side is electrically connected to the bottom pad 50101 through a right conductive via 50109 located on the right side of each PTC conductive polymer layer 50103. The left conductive via 50108 is in direct contact with the top copper electrode layer 50104 on the top surface of the upper PTC conductive polymer layer 50103 and the bottom copper electrode layer 50105 on the bottom surface of the lower PTC conductive polymer layer 50103. The left conductive via 50108 is in direct contact with the upper layer... The bottom copper electrode layer 50105 at the bottom of the PTC conductive polymer layer 50103 and the top copper electrode layer 50104 at the top of the lower PTC conductive polymer layer 50103 are all spaced apart by a certain distance. The right conductive via 50109 is in direct contact with the bottom copper electrode layer 50105 at the bottom of the upper PTC conductive polymer layer 50103 and the top copper electrode layer 50104 at the top of the lower PTC conductive polymer layer 50103. The right conductive via 50109 is also spaced apart by a certain distance from the top copper electrode layer 50104 at the top of the upper PTC conductive polymer layer 50103 and the bottom copper electrode layer 50105 at the bottom of the lower PTC conductive polymer layer 50103.

[0077] Or, such as Figure 17 and Figure 18As shown, the surface mount PTC device 501 includes three or more PTC conductive polymer layers 50103 connected in parallel. Each PTC conductive polymer layer 50103 has a top copper electrode layer 50104 on the right side of its top surface and a bottom copper electrode layer 50105 on the left side of its bottom surface. The bottom copper electrode layer 50105 on the bottom surface of the upper PTC conductive polymer layer 50103 and the top copper electrode layer 50104 on the top surface of the adjacent lower PTC conductive polymer layer 50103 are connected together. An intermediate insulating layer 50110 is provided between the layers. The intermediate insulating layer 50110 is in direct contact with the right side of the bottom surface of the upper adjacent PTC conductive polymer layer 50103 and the left side of the top surface of the lower adjacent PTC conductive polymer layer 50103. A top insulating layer 50106 is provided on the top surface of the uppermost top copper electrode layer 50104. The top insulating layer 50106 is in direct contact with the left side of the top surface of the uppermost PTC conductive polymer layer 50103. The lowermost bottom copper electrode layer 5010... A bottom insulating layer 50107 is provided on the bottom surface of layer 5. The bottom insulating layer 50107 is in direct contact with the right side of the bottom surface of the lowest PTC conductive polymer layer 50103. Top pads 50102 are provided on the left and right sides of the top surface of the top insulating layer 50106, and bottom pads 50101 are provided on the left and right sides of the bottom surface of the bottom insulating layer 50107, respectively. The top pad 50102 on the left side and the bottom pad 50101 on the left side are connected by a left guide located on the left side of each PTC conductive polymer layer 50103. The via 50108 is electrically connected. The top pad 50102 and the bottom pad 50101 on the right side are electrically connected through the right conductive via 50109 located on the right side of each PTC conductive polymer layer 50103. The left conductive via 50108 is spaced a certain distance from each top copper electrode layer 50104 and is in direct contact with each bottom copper electrode layer 50105. The right conductive via 50109 is in direct contact with each top copper electrode layer 50104 and is spaced a certain distance from each bottom copper electrode layer 50105.

[0078] In this invention, the surface mount PTC device 501 does not distinguish between a front and a back side. The front side (top surface) of the surface mount PTC device 501 has top pads 50102 at its left and right ends, and the back side (bottom surface) of the surface mount PTC device 501 has bottom pads 50101 at its left and right ends, respectively. (See...) Figure 14 , Figure 16 and Figure 18 This eliminates the need to distinguish between the front and back sides when packaging the surface-mount PTC device 501, thus improving the packaging speed of the surface-mount PTC device 501.

[0079] The PTC conductive polymer layer 50103 is a PPTC core material or CPTC core material with PTC effect, i.e., positive temperature coefficient effect. The PPTC core material is the core material of a polymer positive temperature coefficient thermistor, and the CPTC core material is the core material of a ceramic positive temperature coefficient thermistor.

[0080] like Figures 11-18 As shown, a fully encapsulated PTC surface mount device is packaged using the aforementioned fully encapsulated PTC surface mount device packaging method. It includes a sub-substrate body layer 503. Two sub-bottom copper pads 502 are distributed on the bottom surface of the sub-substrate body layer 503, and two sub-top copper pads 504 are distributed on the top surface. Each sub-top copper pad 504 corresponds to a corresponding sub-bottom copper pad 502 and is electrically connected through an electrical via 1042. A surface mount PTC device 501 is soldered between the two sub-top copper pads 504. The two sub-top copper pads 504 are respectively soldered to the two bottom pads 50101 of the surface mount PTC device 501. The top surface and sides of the surface mount PTC device 501 are encapsulated by an encapsulation shell 302, and the bottom surface of the surface mount PTC device 501 is encapsulated by the sub-substrate body layer 503. The two sub-bottom copper pads 502 serve as the working pads of the fully encapsulated PTC surface mount device 501.

[0081] Among them, the two top pads 50102 of the surface mount PTC device 501 are arranged symmetrically from left to right, and each top pad 50102 of the surface mount PTC device 501 is arranged symmetrically from top to bottom with the corresponding bottom pad 50101. The encapsulation shell 302 is formed by the cured encapsulation material 301.

[0082] The surface mount PTC device 501 in this invention can achieve overcurrent protection function, and is encapsulated by the substrate body layer 503 and the encapsulation shell 302.

[0083] The encapsulation method for the fully encapsulated PTC surface mount device 5 in this invention has a simple process and its production efficiency is superior to the adhesive coating process in the prior art.

[0084] Example 1

[0085] Multiple arrayed top copper pads 1011 are etched on the top copper foil layer 101 of the double-sided copper-clad substrate 1, and multiple bottom copper pads, equal in number and symmetrically arranged, are etched on the bottom copper foil layer 102. The substrate body layer 103 of the double-sided copper-clad substrate 1 has a length and width of 150 mm, and is made of epoxy resin. Each bottom copper pad and its corresponding top copper pad 1011 form a copper pad group. Multiple... Through-holes 1041 are made that pass through the top copper pads 1011 and the corresponding 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 electrical via 1042 is then sealed with resin buried via treatment. A layer of nickel and tin is electroplated on each top copper pad 1011 to obtain multiple top metal pads 1012, and a layer of nickel and tin is electroplated on each bottom copper pad to obtain multiple bottom metal pads 1021.

[0086] Solder paste with a thickness of 0.08 mm is printed on each top metal pad 1012 using screen printing. A surface mount PTC device 501 is placed between every two vertically arranged adjacent top metal pads 1012 and passed through a reflow oven so that the two adjacent top metal pads 1012 are respectively soldered to the two bottom pads 50101 of the corresponding surface mount PTC device 501. The spacing between two horizontally arranged adjacent surface mount PTC devices 501 and the spacing between two vertically arranged adjacent surface mount PTC devices 501 are both 0.5 mm.

[0087] A 1mm thick positioning frame 2 in a closed state is attached to the top surface of the double-sided copper-clad substrate 1 around the perimeter. The positioning frame 2 surrounds the PTC devices 501 mounted on each surface and the top copper pads 1011.

[0088] 6.5g of epoxy resin encapsulation material 301 (potting compound) is poured into the positioning frame 2, and the double-sided copper-clad substrate 1 bonded to the positioning frame 2 is placed in an oven. The temperature inside the oven is set to 35℃. During this time, the substrate is shaken continuously to accelerate the flow of the potting compound. After self-leveling, the surface mount PTC devices 501 are completely wrapped. The double-sided copper-clad substrate 1 is adjusted to be in a horizontal state, and the temperature inside the oven is controlled to slowly rise to 115℃ at a rate of 5℃ / min and cured for 20 minutes to ensure the uniform heating of the encapsulation material 301. The cured encapsulation material 301 forms an encapsulation shell 302. The encapsulation shell 302 and the double-sided copper-clad substrate 1 work together to completely encapsulate the surface mount PTC devices 501, resulting in a full-board package of surface mount PTC devices.

[0089] Based on the positions of the bottom metal pads 1021 of the surface mount PTC device in the whole board package, the surface mount PTC device in the whole board package is cut with a 0.2mm thick scriber to obtain multiple fully encapsulated PTC surface mount devices 5. Each fully encapsulated PTC surface mount device 5 includes a surface mount PTC device 501 and two sub-bottom metal pads 502 at the bottom as working pads. The surface mount PTC device 501 includes a PTC conductive polymer layer 50103. The top surface and four sides of the fully encapsulated PTC surface mount device 5 are encapsulated by the encapsulation shell 302, and the bottom surface of the fully encapsulated PTC surface mount device 5 is encapsulated by the sub-substrate body layer 503, so as to achieve full encapsulation of the surface mount PTC device 501 on all six sides.

[0090] Example 2

[0091] The difference between Example 2 and Example 1 is that the surface mount PTC device 501 inside the fully encapsulated PTC surface mount device 5 includes two PTC conductive polymer layers 50103 in parallel.

[0092] Example 3

[0093] The difference between Example 3 and Example 1 is that the surface mount PTC device 501 inside the fully encapsulated PTC surface mount device 5 includes three PTC conductive polymer layers 50103 in parallel.

[0094] This invention utilizes encapsulation material 301 to cure adhesive and encapsulate the top surface and four sides of a surface-mount PTC device 501. Simultaneously, it uses the sub-substrate body layer 503 as the bottom surface of the encapsulation to provide bottom support for the surface-mount PTC device 501. This achieves comprehensive encapsulation of all six sides of the surface-mount PTC device 501. This method can completely isolate the surface-mount PTC device 501 from the external environment, avoiding the influence of the external environment while limiting the thermal expansion of the surface-mount PTC device 501 itself, which can effectively improve the durability of the surface-mount PTC device 501.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for packaging a fully encapsulated PTC surface mount device, characterized in that, Includes the following steps: S1. A plurality of arrayed top copper pads (1011) are etched on the top copper foil layer (101) of the double-sided copper-clad substrate (1), and a plurality of bottom copper pads with the same number and corresponding positions as the top copper pads (1011) are etched on the bottom copper foil layer (102). Each bottom copper pad and the corresponding top copper pad (1011) form a copper pad group. Through holes (1041) are drilled through the top copper pads (1011) and the bottom copper pads at each copper pad group. A surface mount PTC device (501) is soldered between every two vertically arranged adjacent top copper pads (1011), wherein two adjacent top copper pads (1011) are respectively soldered to the two bottom pads (50101) of the corresponding surface mount PTC device (501). S2. The closed positioning frame (2) is attached to the top surface of the double-sided copper-clad substrate (1) around the perimeter. The positioning frame (2) surrounds each surface-mounted PTC device (501) and each top copper pad (1011). S3. Pour the encapsulation material (301) into the positioning frame (2), and after leveling and curing, fully encapsulate each of the surface mount PTC devices (501) to obtain a full board packaged surface mount PTC device. S4. According to the position of each bottom copper pad on the bottom of the whole board packaged surface mount PTC device, the whole board packaged surface mount PTC device is cut to obtain multiple fully encapsulated PTC surface mount devices (5). Each fully encapsulated PTC surface mount device (5) includes a surface mount PTC device (501) and has two sub-bottom copper pads (502) on the bottom as working pads.

2. The packaging method for a fully encapsulated PTC surface mount device according to claim 1, characterized in that, In step S1: the double-sided copper-clad substrate (1) further includes a substrate body layer (103), the top copper foil layer (101) is disposed on the top surface of the substrate body layer (103), and the bottom copper foil layer (102) is disposed on the bottom surface of the substrate body layer (103). In step S4: After the entire board of surface mount PTC devices is cut, the substrate body layer (103) is divided into multiple sub-substrate body layers (503). Each sub-substrate body layer (503) has two sub-bottom copper pads (502) distributed on its bottom surface, which serve as working pads for the corresponding fully encapsulated PTC surface mount device (5). Each sub-substrate body layer (503) has two sub-top copper pads (504) distributed on its top surface, which are used to solder to the two bottom pads (50101) of the corresponding surface mount PTC device (501). The two top pads (50102) of the surface mount PTC device (501) are encapsulated by the cured encapsulation material (301).

3. The packaging method for a fully encapsulated PTC surface mount device according to claim 2, characterized in that, Step S1 specifically involves etching multiple arrayed top copper pads (1011) on the top copper foil layer (101) of the double-sided copper-clad substrate (1) and etching multiple bottom copper pads on the bottom copper foil layer (102) in a number equal to and corresponding to the top copper pads (1011). Each bottom copper pad and its corresponding top copper pad (1011) form a copper pad group. Multiple through holes (1041) are drilled at each copper pad group, penetrating the top copper pad (1011) and the corresponding bottom copper pad. A layer of copper is electroplated on the inner wall of each through hole (1041) to obtain multiple electrical vias (1042). Resin-embedded vias are then applied to each electrical via (1042). The process involves sealing each of the electrical vias (1042); electroplating a layer of nickel and tin onto each of the top copper pads (1011) to obtain multiple top metal pads (1012), and electroplating a layer of nickel and tin onto each of the bottom copper pads to obtain multiple bottom metal pads (1021); printing solder paste onto each of the top metal pads (1012) using a screen printing process; attaching a surface mount PTC device (501) between every two vertically arranged adjacent top metal pads (1012); and passing the device through a reflow oven to solder two adjacent top metal pads (1012) to the two bottom pads (50101) of the corresponding surface mount PTC device (501); In step S4: Each of the fully encapsulated PTC surface mount devices (5) has two sub-bottom metal pads (502) at its bottom, which serve as working pads.

4. The packaging method for a fully encapsulated PTC surface mount device according to claim 2, characterized in that, Step S3 specifically involves: pouring the encapsulation material (301) into the positioning frame (2), and after leveling, fully encapsulating each of the surface mount PTC devices (501). Then, placing the double-sided copper-clad substrate (1) bonded to the positioning frame (2) into an oven and heating it to cure the encapsulation material (301). The cured encapsulation material (301) forms an encapsulation shell (302). The encapsulation shell (302) and the double-sided copper-clad substrate (1) work together to fully encapsulate each of the surface mount PTC devices (501), thus obtaining a full-board package of surface mount PTC devices.

5. The packaging method for a fully encapsulated PTC surface mount device according to claim 2, characterized in that: In step S1: the substrate body layer (103) is made of one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide. In step S2: the positioning frame (2) is made of one of epoxy resin, polyimide, polytetrafluoroethylene, silicon carbide or aluminum oxide; In step S3: the encapsulating material (301) is made of thermosetting resin.

6. The packaging method for a fully encapsulated PTC surface mount device according to claim 5, characterized in that: In step S3: the encapsulating material (301) is selected from one or more of epoxy resin, phenolic resin, and unsaturated polyester.

7. The packaging method for a fully encapsulated PTC surface mount device according to claim 2, characterized in that: In step S1: each bottom copper pad and the corresponding top copper pad (1011) are arranged symmetrically vertically; the spacing between two adjacent surface mount PTC devices (501) arranged horizontally is equal to the spacing between two adjacent surface mount PTC devices (501) arranged vertically.

8. The packaging method for a fully encapsulated PTC surface mount device according to claim 2, characterized in that: In step S1: the surface mount PTC device (501) includes a PTC conductive polymer layer (50103); or, the surface mount PTC device (501) includes multiple PTC conductive polymer layers (50103) in parallel.

9. A fully encapsulated PTC surface mount device, packaged using the fully encapsulated PTC surface mount device packaging method as described in any one of claims 2-8, characterized in that: The system includes a sub-substrate body layer (503), on which two sub-bottom copper pads (502) are distributed at the bottom surface and two sub-top copper pads (504) are distributed at the top surface. Each sub-top copper pad (504) corresponds to a corresponding sub-bottom copper pad (502) and is electrically connected through an electrical via (1042). A surface-mount PTC device (501) is soldered between the two sub-top copper pads (504). The sub-top copper pads (504) are soldered to the two bottom pads (50101) of the surface mount PTC device (501). The top surface and each side surface of the surface mount PTC device (501) are encapsulated by the encapsulation shell (302), and the bottom surface of the surface mount PTC device (501) is encapsulated by the sub-substrate body layer (503). The two sub-bottom copper pads (502) serve as working pads for the fully encapsulated PTC surface mount device (5).

10. A fully encapsulated PTC surface mount device according to claim 9, characterized in that: The two top pads (50102) of the surface mount PTC device (501) are arranged symmetrically from left to right, and each top pad (50102) of the surface mount PTC device (501) is arranged symmetrically from top to bottom with the corresponding bottom pad (50101). The encapsulation shell (302) is formed by the cured encapsulation material (301).

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