JP2017534172A - Method for manufacturing a surface mount device - Google Patents

Abstract

A method for manufacturing a surface mount device (100, 900) includes providing at least one core device (120, 920) and at least one lead frame (310). The core device is attached to the lead frame. The core device and lead frame are encapsulated within encapsulant (125, 925). The encapsulant comprises a liquid epoxy having an oxygen permeability of less than about 0.4 cm 3 · mm / m 2 · atm · day when cured. Another method for manufacturing a surface mount device includes forming plaque (1105) from plaque material, forming a plurality of conductive protrusions (915) on the top and bottom surfaces of the plaque, and on the top surface of the plaque. Applying a liquid sealant to cover at least a portion and at least a portion of the bottom surface of the plaque. When cured, the encapsulant has an oxygen transmission rate of less than about 0.4 cm 3 · mm / m 2 · atm · day. The assembly is cut to provide a plurality of components (1120a-c). After cutting, the top surface of each component includes at least one conductive protrusion, the bottom surface of each component includes at least one conductive protrusion, and the top and bottom surfaces of each component include a cured sealant, The core of the component includes a plaque material.

Description

  The present invention relates generally to electrical circuits. More specifically, the present invention relates to a method for manufacturing a surface mount device (SMD).

  Surface mount devices (SMD) are small in size and are used in electrical circuits. In general, SMDs comprise a core device embedded in a housing material such as plastic or epoxy. For example, a core device with resistive characteristics can be embedded in a housing material to create a surface mount resistor resistor (or resistor).

U.S. Patent No. 8525635 US Publication No. 2011/0011533

  One drawback of existing SMDs is that the material used to seal the core device tends to allow oxygen to permeate (or penetrate or penetrate or permeate) into the core device itself. This can be inconvenient for certain core devices. For example, when oxygen enters the core device, the resistance of the positive temperature coefficient core device tends to gradually increase. In some cases, the base resistance may increase by a multiple of 5, resulting in out-of-spec core devices.

  To solve these problems, U.S. Pat. No. 8525635 (by Navarro et al.) Issued September 3, 2013, and U.S. Publication No. published by Jan. 20, 2011 (by Golden et al.). No. 2011/0011533 discloses that the core device can be sealed with a low oxygen permeable oxygen barrier material or the like.

  Current methods for manufacturing the above SMDs produce SMDs that have a relatively large encapsulant volume compared to the total volume of the SMD. For example, the volume of the encapsulant may correspond to 35-40% of the total SMD volume.

In a first aspect, a method for manufacturing a surface mount device includes providing at least one core device and at least one lead frame. The core device is attached to the lead frame. The core device and the lead frame are encapsulated in an encapsulant (or encapsulant or encapsulant). The encapsulant comprises a liquid epoxy having an oxygen transmission rate (or permeability) of less than about 0.4 cm ³ · mm / m ² · atm · day when cured.

In a second aspect, a surface mount device includes a core device and a portion of a lead frame attached to the core device. The encapsulant surrounds at least a part of the core device and a part of the lead frame. The encapsulant corresponds to a cured version (or cured version) of liquid epoxy that is injected around the core device and lead frame. The encapsulant has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day when cured.

In a third aspect, a method for manufacturing a surface mount device includes forming a plaque (or plate or plate or plaque) from a material, a plurality of conductive protrusions (or conductive layers) on the top and bottom surfaces of the plaque. Forming a protrusion or a conductive protrusion and applying a liquid seal to cover (or over) at least a portion of the top surface of the plaque and at least a portion of the bottom surface of the plaque. Including. The liquid encapsulant is cured, and the encapsulant has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day upon curing. The assembly is cut to provide a plurality of components. After cutting, the top surface of each component includes at least one conductive protrusion, the bottom surface of each component includes at least one conductive protrusion, and the top and bottom surfaces of each component include a cured sealant, The core of the component contains the material.

In a fourth aspect, a surface mount device (SMD) includes a core formed from a material, at least one conductive protrusion formed on a top surface of the core, and at least one conductive protrusion formed on a bottom surface of the core; The sealing material which covers at least one part of the upper surface and bottom face of a core is included. The encapsulant has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day.

FIG. 1 is a cross-sectional view of a typical surface mount device (SMD). FIG. 2 illustrates a typical sequence of steps that can be used to manufacture the SMD of FIG. FIG. 3 shows a plurality of SMD element parts. FIG. 4A shows a molding system for sealing the element part shown in FIG. FIG. 4B shows a molding system for sealing the element part shown in FIG. FIG. 5 illustrates an exemplary SMD embodiment that can be manufactured through the manufacturing process illustrated in FIG. FIG. 6 illustrates an exemplary SMD embodiment that may be manufactured through the manufacturing process illustrated in FIG. FIG. 7 illustrates an exemplary SMD embodiment that may be manufactured through the manufacturing process illustrated in FIG. FIG. 8 illustrates an exemplary SMD embodiment that may be manufactured through the manufacturing process illustrated in FIG. FIG. 9 is a cross-sectional view of another typical SMD. FIG. 10 illustrates a typical sequence of steps that can be used to manufacture the SMD of FIG. FIG. 11A shows a plaque having a group of conductive protrusions. FIG. 11B shows a cross-sectional view of the plaque of FIG. 11A. FIG. 11C shows the plaque covered with the top and bottom layers of the encapsulant. FIG. 11D shows a cross-sectional view of the plaque and encapsulant layer of FIG. 11C. FIG. 11E shows a cross-sectional view of the component cut from the plaque and encapsulant layer. FIG. 11F shows a cross-sectional view of the space between components filled with encapsulant. FIG. 11G shows a cross-sectional view of the component with the encapsulant filled in the space between the components being cut. FIG. 11H shows a front view of a component having a conductive layer applied to the ends.

  In order to solve the above problems, a novel method for producing SMD is provided. In one aspect, the process begins by providing an encapsulant having low oxygen permeability within a liquid epoxy or other form. One or more core devices that are the final SMD part (or part or part), a lead frame that defines electrical contacts for the core devices, and other component parts within the cavity of the transfer molding system insert. The encapsulant is inserted into the molding system and injected around the various components. After curing, the assembly is removed from the molding system and the assembly is cut to provide individual SMDs. Various finishing steps (plating, finishing, polishing, etc.) may be performed before or after separating the SMD. This method makes it possible to produce SMDs having a smaller form factor than conventional SMDs. Furthermore, the production cost is lower than the cost associated with the manufacturing of the entire conventional SMD.

  In another embodiment, the material forming the core device is provided in the plaque. A group of conductive protrusions are applied to the top and bottom surfaces of the plaque. A screen printing method is used to screen print the liquid epoxy over the top and bottom surfaces of the plaque. The assembly is cured and separated into components (or singulate). Each component includes a core corresponding to a portion of the original plaque, at least one conductive protrusion extending from the top surface of the core, and at least one conductive protrusion extending from the bottom surface of the core. The exposed surface of the core is covered with additional sealing material to seal the entire core. The end portion of the sealing core is covered with the first conductive layer and the second conductive layer. Each of the conductive layers is formed so as to be in electrical contact with one of the conductive protrusions extending from either the top surface or the bottom surface of the core.

  The encapsulant material described above enables the production of surface mount devices or other small devices that exhibit low oxygen permeability. For example, the encapsulant facilitates the manufacture of a low oxygen permeable surface mount device having a wall thickness of 0.4 mil to 14 mil depending on the form factor.

  FIG. 1 is a cross-sectional view of one embodiment of a surface mount device (SMD) 100. The SMD 100 defines a substantially rectangular body having a top surface 105a, a bottom surface 105b, a first end 110a, a second end 110b, a first contact pad 115a, and a second contact pad 115b. The SMD 100 further includes a core device 120 and an insulating material 125 in which the core device 120 is embedded. In one aspect, the distance between the first end 110a and the second end 110b is about 3.0 mm (0.118 inch) and the width of the SMD 100 is about 2.35 mm (0.092 inch). And the distance between the top surface 105a and the bottom surface 105b may be about 0.5 mm (0.019 inch).

  The core device 120 includes a top surface 120a, a bottom surface 120b, a first end 122a, and a second end 122b. The core device 120 may have a substantially rectangular shape. The distance between the first end 122a and the second end 122b may be about 3.0 mm (0.118 inches). The distance between the top surface 120a and the wisdom surface 120b may be about 0.62 mm (0.024 inches). The distance between the front and back surfaces may be about 0.054 inches. The conductive layer 124ab may cover the top surface 120a and the bottom surface 120b of the core device 120. For example, the conductive layer 124ab may correspond to a 0.025 mm (0.001 inch) thick nickel (Ni) layer and / or a 0.025 mm (0.001 inch) thick copper (Cu) layer. The conductive material may cover the entire top surface 120a and bottom surface 120b of the core device 120 or a smaller portion of the top surface 120a and bottom surface 120b.

  In one aspect, the core device 120 corresponds to a device having the property of deteriorating in the presence of oxygen. For example, the core device 120 may correspond to a low resistance positive temperature coefficient (PTC) device that includes a conductive polymer composition. The electrical properties of the conductive polymer composition tend to deteriorate gradually. For example, in a metal-filled conductive polymer composition containing, for example, nickel, the surface of the metal particles tends to oxidize when the composition is in contact with the ambient atmosphere, and the resulting oxide layer is a metal particle The electrical conductivity of the metal particles is lowered at the time of mutual contact. Many oxidation contact points can result in a five-fold increase in electrical resistance of the PTC device. This can cause the PTC device to exceed the original specification limit. The electrical performance of a device comprising a conductive polymer composition can be improved by minimizing exposure of the composition to oxygen.

The encapsulant 125 is an oxygen barrier material, such as US Pat. No. 8525635 issued by Navarro et al. On September 3, 2013, and US published on Jan. 20, 2011 (by Golden et al.). This can correspond to an oxygen barrier material having characteristics similar to those of the oxygen barrier material disclosed in Japanese Patent Publication No. 2011/0011533. The disclosures of these documents are incorporated herein by reference. Such a material may inhibit oxygen from penetrating into the core device 120, thereby inhibiting degradation of the core device 120 characteristics. For example, the oxygen barrier material may have an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day (1 cm ³ · mil / 100 inches ² · atm · day). The oxygen permeability is measured as cm ³ of oxygen permeating through a sample having an area of 1 m ² and a thickness of 1 mm. Permeability is measured at 0% relative humidity and a temperature of 23 ° C. under a partial pressure difference of 1 atm over 24 hours. Oxygen permeability can be measured using ASTM F-1927 with equipment provided by Mocon, Minneapolis, Minnesota, USA.

  In some embodiments, the encapsulant 125 corresponds to a cured thermoset epoxy having a viscosity of about 1500 cps to 70000 cps and a filler content (or content) of 5 wt% to 95 wt% prior to curing.

  The thickness of the encapsulant 125 from the upper surface 120a of the core device 120 to the upper surface 105a of the SMD 100 is in the range of 0.01 to 0.125 mm (0.0004 to 0.005 inches), for example, about 0.056 mm (. 0022 inches). The thickness from the first end 110a of the SMD 100 to the first end 122a of the core device and the thickness from the second end 110b of the SMD 100 to the second end 122b of the core device are 0.025 to 0.63 mm. (0.001 to 0.025 inches), for example, about 0.056 mm (0.0022 inches).

  The first contact pad 115 a and the second contact pad 115 b are disposed on the bottom surface 105 b of the SMD 100. The first contact pad 115 a is electrically connected to the bottom surface 105 b of the core device 120. The second contact pad 115b is a conductive clip 112, wedge that wraps (or wraps) around one side of the core device 120 to connect the top surface 120 of the core device 120 to the second contact pad 115b. It is electrically connected to the upper surface 120a of the core device 120 through a mold joint (or bond), a wire joint, or the like.

  The first contact pad 115a and the second contact pad 115b are used to fasten the SMD 100 to a printed board or substrate (not shown). For example, the SMD 100 can be soldered to pads on the printed circuit board and / or substrate through the first contact pads 115a and the second contact pads 115b. Each contact pad 115a, 115b may be plated with a conductive material such as copper. The plating can provide an electrical pathway from the outside of the SMD 100 to the core device 120.

  FIG. 2 shows an exemplary sequence of steps that can be used to manufacture the SMD 100 shown in FIG. The steps shown in FIG. 1 will be described with reference to FIGS.

  In block 200, one or more core devices may be provided. With reference to FIG. 3, several core devices 305 may be provided. The core device 305 may correspond to the PTC device described above or a different device. First, to obtain a PTC device, PTC material can be extruded into plaque and then cured. Copper or nickel plating can be applied through standard methods to specific portions of the hardened material to define contact pads and / or interconnects (or interconnects). The PTC material can be cut by standard methods (ie saw, laser, etc.) to separate the PTC device from the PTC material. In certain aspects, conductive epoxies or different types of finishing may be applied to specific portions of each PTC device after separation.

  At block 205, the core device 305 can be attached to the lead frame 310. For example, the core device 305 may be provided so as to cover the lead frame 310. The core device 305 may be attached through hands, pick and place (or pick and place) mechanisms, and / or different techniques.

  The lead frame 310 may define a plurality of contact pads 315a, 315b. The contact pads 315a and 315b may correspond to the first contact pads 115a and 115b shown in FIG. The core device 305 may be attached to contact pads 315a, 315b defined in the lead frame 310. For example, the bottom surface of the core device 305 can be soldered to the top surface of the contact pads 315a, 315b.

  At block 210, the clip interconnect 300 can be attached to the core device 305 and the lead frame 310. The horizontal portion of the clip interconnect 300 can be attached to the top surface of the core device 305 and the opposite end of the clip interconnect 300 can be attached to one of the contact pads 315a. For example, the clip interconnect 300 can be soldered to the top surface of the core device 305 and the contact pad 315a.

  At block 215, the top surfaces of the core device 305, the interconnect 300, and the lead frame 310 may be encapsulated in an encapsulant as shown in FIGS. 4A and 4B.

  Referring to FIG. 4A, a sealing material 407 can be applied through a transfer molding process. In this regard, a molding system 400 may be provided that includes a top 410a and a bottom 410b. A cavity 418 is formed between the upper die 410a and the lower die 410b to form a seal 407 around one or more core devices, interconnects, and lead frames. A vent can be provided in the lower mold so that air can escape. The vent should not be higher than 20 μm and can be positioned either in the cavity, for example in the corner of the cavity. The upper mold 410a includes a transfer pot 408 to which a sealing material 407 is added. The sealing material 407 has a viscosity of about 1500 cps to 70000 cps and may be in the form of a liquid that molds a thermoset epoxy (or thermoset epoxy). In some embodiments, the epoxy may include a filler content of 5% to 95% by weight.

  As shown in FIG. 4B, the plunger 405 of the molding system 400 is pushed into the upper side 410a to apply a force to the sealant 407 through the sprue 407 and into the cavity 418. The transfer pot 408 can be heated to a temperature of about 20 ° C. to 30 ° C. to reduce the viscosity of the encapsulant 407 prior to insertion of the plunger. A transfer pressure of about 150 psi to 300 psi can be applied to the plunger 405.

  Returning to FIG. 2, at block 220, the encapsulant 407 may be partially or fully cured. For example, the encapsulant 407 can be placed in the molding system 400 to cure the encapsulant 407 for about 1-5 minutes. In some embodiments, the transfer pot (mold) 408 can be heated to about 120-180 degrees to accelerate curing.

  At block 225, the upper mold 410a and the lower mold 410b of the molding system 400 are opened. An ejector pin 415 of the molding system 400 can be pushed down the cavity to push the assembly out of the molding system 400. After removal, a nickel alloy and / or copper finish may be applied to a predetermined portion of the assembly to release the SMD from the assembly. For example, the SMD can be cut from the cured structure with a saw, laser, or other tool. Additional finishing and / or polishing steps may be performed to produce the final SMD. For example, after separation, a solderable nickel alloy finish may be applied (see FIG. 8).

  Figures 5-8 illustrate various alternative SMD embodiments that may be manufactured through the method described above or variations thereof. Referring to FIG. 5, the SMD 500 may include a core device 120 encapsulated within an encapsulant 125 that may correspond to the encapsulant described above. In this aspect, no interconnect is used. Rather, a first copper plate 505 a and a second copper plate 505 b can be applied to the opposite ends of the core device 120. The copper plates 505a, 505b can be finished with a solderable nickel alloy finish such as NiSN or NiAu. The copper plate can be applied to the core device 120 prior to sealing.

  Referring to FIG. 6, the SMD 700 may include a core device 120 that is encapsulated within an encapsulant 125 that may correspond to the encapsulant described above. A first conductive epoxy coating 605a and a second conductive epoxy coating 605b may be applied to each end of the core device 120 prior to sealing. Vias 607a and vias 607b are formed below the SMD 600 below each end of the core device 120 and may be plated with a conductive material to facilitate electrical contact with the core device 120 from the outside of the SMD 100. Finished portions of solderable nickel alloy finished pads 609a, 609b may be formed around the via opening on the bottom side of the SMD 600.

  Referring to FIG. 7, the SMD 700 may include a core device 120 that is encapsulated within an encapsulant 125. A sealing material 125 that can correspond to the above-described sealing material is provided at each end of the SMD 700. A gap 705 is formed in the conductive layer 124 a and the conductive layer 124 b that cover the top and bottom surfaces of the core device 120.

  Referring to FIG. 8, the SMD 800 may include a core device 120 encapsulated within an encapsulant 125 that may correspond to the encapsulant described above. A first conductive epoxy coating 805a and a second conductive epoxy coating 805b may be applied to each end of the core device 120 prior to sealing. Solderable nickel alloy finishes 810a, 810b may be provided to cover the first conductive epoxy coating 805a and the second conductive epoxy coating 805b.

  As shown in the figure, the novel manufacturing method can manufacture various forms of SMD. Furthermore, this method can produce SMDs having a smaller form factor than SMDs produced using standard methods. Although SMDs and methods of manufacturing SMD have been described with reference to particular embodiments, those skilled in the art will appreciate that various modifications can be made and equivalents can be substituted without departing from the scope of the claims of this application. Many other modifications may be made to adapt a particular situation or material to the teachings without departing from the scope of the claims. As a result, SMDs and SMD manufacturing methods are not limited to the specific embodiments disclosed, but are intended to include any embodiment within the scope of the claims.

  FIG. 9 is a cross-sectional view of an exemplary surface mount device (SMD) that can be formed through the process shown in FIG. The SMD 900 defines a generally rectangular body and includes a core device 920 and upper and lower conductive protrusions 915a and 915b that are electrically connected to the top and bottom surfaces of the core device 920, respectively. The sealing material 925 is formed around the core device 920. The conductive protrusions 915 a and 915 b extend through the sealing material 925. The first conductive end portion 910a and the second conductive end portion 910b are formed to cover the sealed end portion of the core device 920. Each of the first conductive end 910a and the second conductive end 910b includes a first conductive end 910a and a second conductive end 910a that are in electrical contact with the upper conductive protrusion 915a and the bottom conductive protrusion 915b. One of the upper and bottom conductive protrusions 915 is at least partially covered to provide two conductive ends 910b. In one aspect, the SMD 900 boundary portion is about 3.0 mm (0.118 inches) long, about 0.5 mm (0.019 inches) high, and about 2.35 mm (0.092 inches) high. Define a rectangular volume with depth.

  Core device 920 includes many of the same features as core device 120 described above. For example, a conductive layer (not shown for clarity) may cover the top and bottom surfaces of the core device 920. In this case, the upper and bottom conductive protrusions 915a and 915b are connected (or coupled) to the conductive layer. Core device 920 may have the material properties of core device 120 described above.

  The encapsulant 924 can have the material properties of the encapsulant 925 described above. However, in this example, the encapsulant 125 may correspond to a cured thermoset epoxy having a viscosity of about 1500 cps to 70000 cps and a filler content of 5 wt% to 95 wt% before curing.

  The thickness or wall thickness of the encapsulant 125 can be about 0.4 mil to 14 mil. The wall thickness may be uniform on all sides or different.

  FIG. 10 shows an exemplary process that may be used to manufacture the SMD 900 shown in FIG. The process shown in FIG. 10 is well understood with reference to FIGS.

  At block 1000, a PTC plaque is provided. For example, as indicated by the PTC plaque 1105 shown in FIGS. 11A and 11B, the PTC material can be extruded through a die to form a sheet-like PTC material having a desired cross-section.

  In block 1005, a conductive surface is formed to cover the top and bottom surfaces of the plaque. The conductive surface can be copper or a different conductive material.

  In block 1010, conductive protrusions 1110 (FIGS. 11A and 11B) may be formed on the top and bottom surfaces of the plaque 1105 located at predetermined portions of the plaque 1105 that can be uniformly singulated into individual cores. Conductive protrusions 1110 may be formed after the conductive surfaces are formed on the top and bottom surfaces of the plaque. Also, the initial thickness of the conductive surface formed in the block 1105 can be selected to be the same as the desired height of the conductive protrusion 1110. The thickness of the conductive surface can then be reduced through a reduction process, such as a chemical and / or mechanical process, at a predetermined portion and can remain intact at other portions that are not affected by it. The unaffected region may correspond to the conductive protrusion 1110.

  At block 1015, the plaque is sealed and cured within the sealant 1115 as shown in FIGS. 11C and 11D. The encapsulant 1115 is applied over the plaque through a screen printing method so that the encapsulant is provided in liquid form and can be pressed through the screen against the top and bottom surfaces of the plaque 1105. The liquid form sealant may have a viscosity of about 1500 to 70000 cps. The screen has an opening portion through which the liquid sealing material flows and a closed portion that suppresses the liquid sealing material from reaching the plaque. These portions may be configured such that the encapsulant can cover the entire surface area of the plaque 1105 except for the conductive protrusion 1110. In another aspect, the conductive protrusion 1110 can be covered by a liquid sealant and subsequently exposed by grinding the sealant after the sealant is cured.

  In block 1020, a tape layer 1125 may be applied to cover the conductive protrusion 1110 that extends from the bottom surface of the plaque 1105. The plaque 1105 is then cut to unify the plaque 1105 into pieces 1120a-c as shown in FIG. 11E. The plaque 1105 can be cut using standard techniques (ie saw, laser, etc.) to unify the plaque into separate components 1120a-c. Each component 1120a-c includes a layer of encapsulant on the top and bottom surfaces of the core 1105a and at least a pair of conductive protrusions 1110 extending through the encapsulant (one conductive on the top surface of the core 1105a). And the other conductive protrusion on the bottom surface of the core 1105a. Tape layer 1125 is used to hold components 1120a-c together for subsequent processing operations.

  At block 1025, a cut formed between the components 1120a-c singulated so that the encapsulant filler 1130 covers the surface of the core 1105a in the components 1120a-c exposed by the cut as shown in FIG. 11F. Inserted into the part. After the sealing material filler 1130 is cured, the sealing material filler 1130 is cut and the tape layer 1125 is removed as shown in FIG. 11G. The encapsulant filler 1130 is cut to leave a portion of the encapsulant covering the already exposed sidewalls of the cores 1105a of the components 1120a-c.

  At block 1030, the ends of the singulated components 1120a-c may be plated to provide the first conductive end 910a and the second conductive end 910b described above. For example, conductive epoxy layers 1130a, 1130b can be applied to cover the ends of the singulated components 1120a-c. The conductive epoxy layers 1130a and 1130b may cover part or all of the conductive protrusions 1110. In some embodiments, a solderable nickel alloy finish may be provided to cover the conductive epoxy layers 1130a, 1130b.

  As illustrated, the novel manufacturing method can manufacture various forms of SMDs. Furthermore, the novel manufacturing method can manufacture SMDs with smaller form factors that can hold higher holding currents than SMDs manufactured using conventional methods. For example, the process shown in FIG. 10 may be somewhat adapted to produce an SMD such as the SMD shown in FIGS. Although SMD and methods for manufacturing SMD have been described with reference to particular embodiments, those skilled in the art will recognize that various modifications can be made and equivalents can be substituted without departing from the scope of the claims of this application. Will be understood. Many other modifications may be made to adapt a particular situation or material to the teachings without departing from the scope of the claims. As a result, SMDs and SMD manufacturing methods are not limited to the specific embodiments disclosed, but are intended to include any embodiment within the scope of the claims.

Claims (17)

A surface mount device,
Core device;
A portion of a lead frame attached to the core device; and a sealant surrounding at least a portion of the core device and a portion of the lead frame;
A surface mount device, wherein the encapsulant corresponds to a curable form of liquid epoxy and has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day.   The surface mount device of claim 1, wherein the encapsulant corresponds to a thermoset epoxy, and preferably the epoxy has a viscosity of about 1500 cps to 3000 cps prior to curing.   The surface mount device of claim 2, wherein the epoxy comprises a filler content of about 10 wt% to 50 wt%.   The lead frame defines a first contact pad and a second contact pad, preferably the first contact pad is in electrical contact with the first end of the core device, and the surface mount device is one of the core devices. The surface mount device of claim 1, comprising a conductive clip that wraps around the side of the substrate and thereby electrically connects the second contact pad to the second end of the core device.   The surface mount device of claim 1, wherein the at least one core device is a positive temperature coefficient (PTC) device. A method for manufacturing a surface mount device according to claim 1, comprising:
Providing at least one core device and at least one lead frame;
Attaching the core device to the lead frame;
Encapsulating at least a portion of at least one core device and a portion of at least one lead frame in an encapsulant;
The method wherein the encapsulant comprises a liquid epoxy having an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day when cured.   Encapsulating at least a portion of at least one core device and a portion of at least one lead frame within the encapsulant includes performing transfer molding through a transfer molding system, wherein the encapsulant is at least The method of claim 6, wherein the method is around at least a portion of one core device and a portion of at least one lead frame.   And further comprising inserting a sealant into the pot of the transfer molding system and heating the pot to a temperature of about 20 ° C. to 30 ° C., preferably inserting a plunger of the transfer molding system into the pot. Generating a pressure of about 150 psi to 300 psi to apply a force to at least a portion of the at least one core device and a portion of the at least one lead frame through the sprue of the transfer molding system. The method of claim 7 comprising.   The method of claim 6, wherein the transfer molding system comprises an upper mold and a lower mold, and the lower mold includes at least one vent having a height of 20 μm or less. A surface mount device (SMD),
A core formed from a material;
At least one conductive protrusion formed on the top surface of the core and at least one conductive protrusion formed on the bottom surface of the core;
Comprising a sealing material covering at least a part of the top and bottom surfaces of the core;
A surface mount device wherein the encapsulant has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day.   The surface mount device of claim 10, wherein the core is formed from a positive temperature coefficient (PTC) device and the encapsulant corresponds to a thermoset epoxy.   The first conductive layer is in electrical communication with at least one conductive protrusion formed on the top surface of the component, and the second conductive layer is in electrical communication with at least one conductive protrusion formed on the bottom surface of the component. The surface-mount device according to claim 10, further comprising a first conductive layer and a second conductive layer formed to cover the sealed end portion of the core so as to be in communication with each other. A method for manufacturing a surface mount device according to claim 10, comprising:
Forming plaque from the material;
Forming a plurality of conductive protrusions on the top and bottom surfaces of the plaque;
Applying a liquid sealant to cover at least a portion of the top surface of the plaque and at least a portion of the bottom surface of the plaque;
Curing the liquid sealant; and cutting the cured sealant and plaque to provide a plurality of components;
The cured encapsulant has an oxygen transmission rate of less than about 0.4 cm ³ · mm / m ² · atm · day;
After cutting, the top surface of each component includes at least one conductive protrusion, the bottom surface of each component includes at least one conductive protrusion, the top and bottom surfaces of each component include a cured sealant, and The method wherein the core of each component comprises plaque material.   14. The method of claim 13, wherein the plaque material corresponds to a positive temperature coefficient (PTC) device.   The encapsulant corresponds to a thermosetting epoxy having a viscosity of about 1500 cps to 70000 cps when in the liquid state, preferably the epoxy comprises a filler content of about 5 wt% to 95 wt%. Item 14. The method according to Item 13.   After cutting, the method applies an additional liquid sealant to the sidewalls of each component exposed after the cut, and the liquid sealant is cured and exposed by the cured sealant And preferably the cured additional encapsulant fills the space between the sidewalls of adjacent components and connects to adjacent components, and the method includes curing 14. The method of claim 13, further comprising cutting an intermediate portion of the additional encapsulant to separate the connected components.   Applying the liquid sealant includes screen printing the liquid sealant on the plaque, and preferably the screen utilized for screen printing is such that the liquid sealant is in each of the plurality of conductive protrusions. The method of claim 13, wherein the method is configured to suppress covering at least a portion.

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