KR20170070159A - Method for manufacturing a surface mount device - Google Patents

Abstract

A method of fabricating a surface mount device (100, 900) includes providing at least one core device (120, 920) and at least one leadframe (310). The core device is attached to the lead frame. The core device and the lead frame are encapsulated within the encapsulant 125, 925. The encapsulant comprises a liquid epoxy which when cured has an oxygen permeability of less than about 0.4 cm ³ · mm / m ² · atm · day. Another method of fabricating a surface mount device includes forming a plaque 1105 from a material, forming a plurality of conductive protrusions 915 on the upper and lower surfaces of the plaque, And applying a liquid encapsulant over at least a portion of the lower and the lower surface. When cured, the capsules have an oxygen permeability of less than about 0.4 cm ³ · mm / m ² · atm · day. The assembly is cut to provide a plurality of components 1120a, 1120b, and 1120c. After cutting, the top surface of each component includes at least one conductive protrusion, and the bottom surface of each component includes at least one conductive protrusion, and the top surface and bottom surface of each component are coated with a cured capsule , And the core of each component includes a material.

Description

[0001] METHOD FOR MANUFACTURING A SURFACE MOUNT DEVICE [0002]

The present invention relates generally to electronic circuitry. More particularly, the present invention relates to a method for manufacturing a surface mount device (SMD) of the present invention.

Surface mount devices (SMDs) are used in electronic circuits because of their small size. Generally, SMDs include a core device embedded within a housing material, such as plastic or epoxy. For example, a core device with resistive properties can be embedded in a housing material that makes a surface mount resistor.

One disadvantage of existing SMDs is that the material used to encapsulate the core device tends to allow oxygen to permeate into the core device itself. For example, if oxygen is allowed to enter the core device, the resistance of the positive-temperature-coefficient core device tends to rise over time. In some cases, the base resistance may increase to a factor of five (5) and may deviate from the core device spec.

To overcome these problems, the core device is disclosed in U.S. Patent No. 8,525,635 (Navarro et al.), Filed September 3, 2013, and in U.S. Patent Application Publication No. 2006/0011533, published January 20, And can be encapsulated with low oxygen permeability such as oxygen barrier material.

Current methods of manufacturing SMDs such as those mentioned above yield SMDs with a relatively large encapsulant volume compared to the total volume of SMDs. For example, the volume of the capsule may be 35-40% of the total volume.

In one aspect, a method of fabricating 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 within the capsule. The encapsulant contains a liquid epoxy which, when cured, has an oxygen permeability of less than about 0.4 cm ³ · mm / m ² · atm · day.

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 portion of the lead frame and the core device. The encapsulant corresponds to a cured version of a liquid epoxy injected around the core device and the leadframe. The capsule has an oxygen permeability less than about 0.4 cm ³ · mm / m ² · atm · day.

In a third aspect, a method of fabricating a surface mount apparatus includes forming a plaque from a material, forming a plurality of conductive protrusions on a lower surface and a top surface of the plaque, And applying a liquid encapsulant over at least a portion of the top surface. When the liquid encapsulant is cured and cured, the encapsulant has an oxygen permeability less than about 0.4 cm ³ · mm / m ² · atm · day. The assembly is cut to provide a plurality of components. After cutting the top surface of each component comprises at least one protrusion, the bottom surface and the top surface of each component comprise a hardened capsule, and the core of each component comprises a material.

In a fourth aspect, a surface mount device (SMD) comprises a core formed from a material, at least one conductive protrusion formed on an upper surface of the core, at least one conductive protrusion formed on a lower surface of the core, And a capsule which covers at least a part of the surface and the surface of the titanium carbide. The capsules have an oxygen permeability less than about 0.4 cm ³ · mm / m ² · atm · day.

Lt; / RTI >

1 is a cross-sectional view of an exemplary surface mount device (SMD).
FIG. 2 illustrates an exemplary group of operations that may be utilized to fabricate the SMD of FIG.
3 shows component cross-sections of a plurality of SMDs.
4A and 4B illustrate a molding system for encapsulation of the component cross-sections shown in FIG.
5-8 illustrate the completion of an exemplary SMD that may be fabricated through the fabrication operation described in FIG.
Figure 9 shows a cross section of another exemplary SMD.
10 illustrates an exemplary group of operations that may be utilized to fabricate the SMD of FIG.
11A shows a plaque having a group of conductive protrusions.
11B is a cross-sectional view of the plaque of FIG.
Figure 11C shows a plaque covering the lower and upper layers of the capsule.
11D is a cross-sectional view of the plaque and capsule layers of FIG. 11C.
11E is a cross-sectional view of the components being cut from the encapsulating layers and plaque.
11F is a cross-sectional view of the space between the capsule-filled components.
Figure 11G is a cross-sectional view of the constituent urethra that cuts the capsule filled into the space between the components.
11H is a front view of components having conductive layers added to the ends.

In order to overcome the problems mentioned above, a new method for manufacturing SMDs is provided. In one embodiment, the process begins by providing a capsule with low oxygen permeability in liquid epoxy or other form. Other component sections, which are one or more core devices, a lead frame that defines electrical contacts for core devices, and a final SMD, are connected to a joint of a transfer molding system into the cavity. The encapsulant is introduced into the molding system and is dispensed around various components. After curing, the assembly is removed from the molding system and cut to provide independent SMDs. Various final operations (plating, finishing, polishing, etc.) may be performed before or after the SMDs are separated. Using this process, it is possible to manufacture SMDs with smaller form factors than conventional SMDs. In addition, the production cost is lower than the costs associated with the manufacture of the entire conventional SMDs.

In another embodiment, the material forming the above-mentioned core device is provided in a plaque. A group of conductive protrusions is applied to the upper and lower surfaces of the plaque. A screen-printing process is used to screen-print the liquid epoxy onto top and bottom surfaces. The assembly is cured and singulated into the components. Each component includes a core corresponding to a portion of the original plaque, at least one conductive protrusion extending from the top of the core, and at least one conductive protrusion extending from the bottom of the core. The exposed surface of the core is covered with an additional encapsulant to encapsulate the entire core. The ends of the encapsulated core are covered with first and second conductive layers. Each of the conductive layers is formed to be an electrical contact having one of the conductive protrusions extending from the bottom or bottom of the core.

The aforementioned encapsulating materials enable the production of surface mount devices or other small devices that exhibit low oxygen permeability. For example, the encapsulant is easy to fabricate low oxygen permeability surface mount devices having a wall thickness between 0.4 millimeters and 14 millimeters depending on the form factor.

Figure 1 shows a cross section of one embodiment of a surface mount device (SMD) 100. The SMD 100 has 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 It generally defines a rectangular body. The SMD 100 includes a core device 120 and an insulator material in which the core device 120 is embedded. In one embodiment, the spacing between the first and second ends 110a, 110b may be about 0.118 inches, and the width of the SMD 100 may be about 0.092 inches, The spacing between the top and bottom surfaces 105a, 105b may be about 0.019 inches.

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 generally rectangular shape. The spacing between the first and second ends 122a, 122b may be about 0.118 inches. The spacing between the top and bottom surfaces 120a, 120b may be about 0.62 mm (0.024). The spacing between the front and rear surfaces may be about 0.054 inches. The conductive layers 124a and 124b may overlay the top and bottom surfaces 120a and 120b of the core device 120. [ For example, the conductive layers 124a and 124b may correspond to a 0.001 inch thick layer of nickel (Ni) and / or a 0.025 mm (0.001 inch) thick layer of copper (Cu). The conductive material covers the entire upper and lower surfaces 120a, 120b of the core device 120 or a smaller portion of the upper and lower surfaces 120a, 120b.

In one embodiment, the core device 120 corresponds to a device having properties that deteriorate under the presence of oxygen. For example, the core device 120 may correspond to a low-resistance positive-temperature-coefficient (PTC) device comprising a conductive polymer composition. The electrical properties of the conductive polymer composition tend to deteriorate over time. For example, in such metal-filled conductive polymer compositions that house nickel, the surfaces of the metal particles tend to oxidize when the structure contacts ambient air, and the resulting The oxidation layer reduces the conductivity of the particles when in contact with each other. Multiple oxidized contact points can increase the electrical resistance of the PTC device to five times or more. This causes the PTC device to exceed the limit of the original specification. The electrical performance of devices that accommodate conductive polymer structures can be improved by minimizing the exposure of the structure to oxygen.

Capsule 125 is similar to that disclosed in U.S. Patent No. 8,525,635, filed September 3, 2013 (Nabaros et al.), And U.S. Application No. 2011/0011533, filed January 20, 2011 Barrier materials, such as oxygen-barrier materials, including those disclosed herein, and the disclosures of which are incorporated herein by reference. This material can prevent oxygen from spreading into the core device 120, and thus deterioration of the characteristics of the core device 120 is prevented. For example, the oxygen-barrier material may have a surface area of about 0.4 cm < ³ > .mm / m < ² >.atm, measured as cubic centimeters of oxygen diffusing through a sample having a thickness of one millimeter, Oxygen permeability of less than 1 day (1 cm ³ · yl / 100 in ² · atm · day). The permeation rate is measured at a relative humidity of 0% and at a temperature of 23 [deg.] C under one partial pressure differential (differential pressure) for 24 hours. Oxygen permeability can be measured using ASTM F-1927 as equipment supplied by Mocon, Inc. of Minneapolis, Minnesota.

In one embodiment, the encapsulant 125 corresponds to a cured thermoset epoxy having a viscosity between about 1500 cps and 70,000 cps, and a filler content between 5 and 95% by weight prior to curing.

The thickness of the encapsulant 125 from the top surface 120a of the core device 120 to the top surface 105a of the SMD 100 may range from 0.01 to 0.125 mm (0.0004 to 0.005 in) mm (0.0022 in). The thickness of the capsule 125 from the first and second ends 110a and 110b of the core device 125 to the respective first and second ends 122a and 122b of the SMD 100 is And may be in the range of 0.025 to 0.63 mm (0.001 to 0.025 in), for example, approximately 0.0022 inches.

The first and second contact pads 115a and 115b are arranged on the lower surface 105b of the SMD 100. [ The first contact pad 115a is electrically coupled to the bottom surface 105b of the core device 120. [ The second contact pad 115b is electrically connected to the upper end of the core device 120 through a conductive clip 112, a wedge bond, a wire bond, And is electrically coupled to surface 120a thereby coupling top surface 120 of core device 120 to second contact pad 115b.

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

FIG. 2 illustrates an exemplary group of operations that may be utilized to fabricate the SMD 100 disclosed in FIG. The operations shown in Fig. 1 are described with reference to Figs. 3 and 4. Fig.

At block 200, one or more core devices may be provided. Referring to FIG. 3, several core devices 305 may be provided. The core devices 305 may correspond to the above-mentioned PTC device or other device. To obtain PTC devices, the PTC material can be extruded first onto the plaque and then cured. Copper or nickel plating may be applied through conventional processes to specific sections of the cured materials to define contact pads and / or interconnects. The PTC material is then cut (i.e., sawed, laser, etc.) using conventional processes that separate the PTC devices from the material. In some embodiments, conductive epoxy or other types of other finishes may be applied to specific sections of each PTC device after separation.

At block 205, the core devices 305 may be secured to the lead frame 310. For example, the core devices 305 may be located on the leadframe 310. [ The core devices 305 may be fixed by hand, via a pick-and-place machine, and / or through other processes.

The lead frame 310 may define a plurality of contact pads 315a and 315b. The contact pads 315a and 315b may correspond to the first and second contact pads 315a and 315b shown in FIG. For example, the bottom surfaces of the core devices 305 may be soldered to the top surfaces of the contact pads 315a, 315b. At block 210, clip interconnects 300 may be secured to core devices 305 and lead frame 310. The horizontal sections of the clip interconnections 300 may be secured to the top surface of the core devices 305 and the opposite end of the clip interconnections 300 may be secured to one of the contact pads 315a have. For example, the clip interconnects 300 may be soldered to the top surfaces of the core devices 305 and contact pads 315a.

At block 215, the tops of the core devices 305, interconnects 300, and leadframe 310 may be encapsulated in a capsule as shown in FIGS. 4A and 4B.

Referring to FIG. 4A, the encapsulation material 407 may be applied through a transfer molding process. In this regard, a mold system 400 is provided that includes a cop 410a and a drag 410b. Cavity 418 is formed between cop 410a and drag 410b to form encapsulant 407 around one or more core devices, interconnects, and leadframe. A vent is provided in the drag to permit air escaping. The hole should not be larger than 20 μm and may be located in the cavity, for example at any corner of the cavity. The COP 410a includes a transfer pot 408 to which the capsule 407 is added. The encapsulant 407 may be in the form of a liquid molding thermoset epoxy having a viscosity of between about 1500 cps and 70,000 cps. In some embodiments, the epoxy may comprise from 5 to 95 weight percent of the filler content.

4B, a plunger 405 of the mold system 400 is pressed into the cavity and into the cavity 418 and through the sprue 407 to force the encapsulant 407 . The transfer pod 408 may be heated prior to insertion of the plunger to a temperature of about 20 ° C to 30 ° C with a low viscosity of the encapsulant 407. Transfer pressures between about 150 psi and 300 psi can be applied to the plunger 405.

Referring to Fig. 2, at block 220, the encapsulant 407 is partially or fully cured. For example, the encapsulant 407 may be left in the mold system 400 for about 1-5 minutes allowing the encapsulating material 407 to cure. In some implementations, the transfer pot (mold) 408 may be heated to about 120-180 ° C to accelerate the cure.

At block 225, the cop 410a and drag 410b of the mold system 400 are opened. The ejector pin 415 of the mold system 400 may be pushed into the lower side of the cavity to seal the assembly out of the mold system 400. After removal, a nickel alloy and / or a copper finish may be applied to the sections of the assembly. The SMDs may be separated from the assembly. For example, SMDs can be cut from a cured configuration with a saw, laser, or other tool. Additional end losses and / or grinding steps may be performed to produce the final version of the SMDs. For example, a solderable nickel alloy finish can be applied after separation (as shown in FIG. 8).

5-8 illustrate various alternative SMD implementations that may be fabricated through the above-described process or variations thereof. 5, the SMD 500 may include a core device 120 encapsulated within a capsule 125, which may correspond to a capsule as described above. In this embodiment, and interconnections are not used. Rather, the first and second copper plates 505a, 505b may be applied to opposite ends of the core device 120. The copper plates 505a, 505b may be finished with a pourable nickel alloy finish, such as NiSN or NiAu. The copper plates may be applied to the core devices 120 prior to encapsulation.

Referring to FIG. 6, the SMD 700 may include a core device 120 that is encapsulated within a capsule. This may correspond to the capsules mentioned above. The first and second conductive epoxy coatings 605a and 605b may be applied to the respective ends of the core device 120 prior to encapsulation. The vias 607a and 607b may be formed on the underside of the SMD 600 under each end of the core devices 120 and electrically contact the core device 120 from the outside of the SMD 100. [ Gt; and / or < / RTI > Solderable nickel alloy finished pads 609a and 609b may be formed around the via openings in the bottom side of the SMD 600. The solderable nickel alloy finished pads 609a and 609b may be formed around the via openings.

Referring to FIG. 7, the SMD 700 may include a core device 120 encapsulated within a capsule 125. Capsule 125, corresponding to the capsules described above, is provided on each end of SMD 700. A gap 705 is formed in the conductive layers 124a and 124b, which covers the top and bottom surfaces of the core device 120. [

8, the SMD 800 may include a core device 120 encapsulated within a capsule 125, which may correspond to a capsule, as described above. The first and second conductive epoxy coatings 805a and 805b may be applied to each end of the core device 120 prior to encapsulation. Solderable nickel alloy finishes 810a, 801b may be provided over the first and second conductive epoxy coatings 805a, 805b.

As shown, the new fabrication method is capable of producing SMDs of various configurations. In addition, this method is capable of producing SMDs with smaller form factors than those produced using conventional processes. It will be understood by those skilled in the art that while the method for fabricating SMD and SMD is described in the specific embodiments, various modifications may be made and equivalents may be substituted without departing from the scope of the claims of the claims. Many other modifications will tailor certain situations or materials to teachings that do not depart from the scope of the claims. Accordingly, it is intended that specific embodiments disclosed in which a method for manufacturing SMDs and SMDs are disclosed, but are not intended to limit any practical examples that are within the scope of the claims.

FIG. 9 is a cross-sectional view of an exemplary surface mount device (SMD) 900 that may be formed through the operations described in FIG. The SMD 900 includes top and bottom conductive protrusions 915a and 915b that are generally defined as rectangular bodies and are in electrical contact with the top and bottom surfaces of the core device 920 and the core device 920, respectively. The conductive protrusions 915a and 915b extend through the capsule 925. [ First and second conductive ends 910a and 910b are formed above the encapsulated ends of the core device 920. [ Each of the first and second conductive ends 910a and 910b includes upper and lower conductive protrusions 910a and 910b leading to first and second conductive ends 910a and 910b in electrical contact with the upper and lower conductive protrusions 915, Lt; RTI ID = 0.0 > 915 < / RTI > In one implementation, the bounds of the SMD 900 are rectangular with a length of about 3.0 mm (.118 in), a height of about 0.5 mm (.019 in), and a depth of about 2.35 mm (0.092 in) Define the volume.

The core device 920 includes many of the same features as the core device 120 mentioned above. For example, a conductive layer (not explicitly shown) may cover the top and bottom surfaces of the core device 920, in which case the top and bottom conductive protrusions 915a, 915b are coupled to the conductive layer. The core device 920 may have the material properties of the core device 120 mentioned above.

Capsule 926 may have the material properties of capsule 925 mentioned above. In this case, however, the encapsulant 125 may correspond to a cured thermosetting epoxy having a viscosity between about 1500 cps and 70,000 cps prior to curing, and a fill content between 5 and 95% by weight.

The wall thickness or thickness of the capsule 125 may be between 0.4 and 14 millimeters. The wall thickness can be uniform or different on all sides.

FIG. 10 illustrates exemplary operations that may be used to fabricate the SMD 900 disclosed in FIG. The operations shown in Figure 10 are best understood with reference to Figures 11a-h.

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

At block 1005, a conductive surface may be formed on top and bottom surfaces of the plaque. The conductive surface may be copper or other conductive material.

In block 1010, conductive protrusions 1110 (FIGS. 11A and 11B) may be formed on the top and bottom surfaces of plaque 1105 in the receptions of plaque 1105 which will eventually be singulated into individual cores . Conductive protrusions 1110 may be formed after a conductive surface is formed on the top and bottom surfaces of the plaque. Alternatively, the initial thickness of the conductive surface formed in block 1105 may be chosen to be the same according to the preferred height of conductive protrusions 1110. [ The thickness of the conductive surface can then be reduced in the section through a subtractive process such as a chemical and / or mechanical process, and the other sections are unaffected. The unaffected area will correspond to the conductive protrusions 1110.

At block 1015, the plaque is encapsulated within the capsule 1115 as shown in Figures 11C and 11D, and allowed to cure. Capsule 1115 can be applied over the plaque through a screen-printing process whereby the capsule is provided in liquid form and pressed onto the top and bottom surfaces of plaque 1105 and through the screen. The liquid form of the capsule may have a viscosity between about 1500 and 70,000 cps. The screen has open sections through which the liquid capsule flows and has a closed section that closes the liquid capsule from reaching the plaque. The sections may be configured to allow encapsulant to cover the entire surface area of the plaque 1105 except for the conductive protrusions 1110. [ In other embodiments, the conductive protrusions 1110 may be covered with a liquid capsule and then exposed by polishing the capsule after the capsule is cured.

At block 1020, a tape layer 1125 may be applied over the conductive protrusions extending from the lower end of the plaque 1105. The plaque 1105 may then be cut to unify the plaque 1105 into the sections 1120a, 1120b, 1120c as shown in Figure 11e. The plaque 1105 can be cut (i.e., sawed, laser, etc.) using conventional processes to unify the plaque into the separate components 1120a, 1120b, 1120c. Each of the components 1120a, 1120b and 1120c includes at least one pair of conductive protrusions 1110, one on the top surface of the core 1105a and the other on the bottom surface of the core 1105a, A top surface of core 1105a, and a layer of encapsulant on the bottom surface. The tape layer 1125 is used to secure the components 1120a, 1120b, 1120c0 together for subsequent plucking operations.

At block 1025 the encapsulant filler 1130 covers such surfaces of the core 1105 within the components 1120a, 1120b and 1120c that were exposed by cutting, as shown in Figure 11f. Are inserted into cuts formed between the unified components 1120a, 1120b, and 1120c. After the capsule filler 1130 is cured, the capsule filler 1130 is cut and the tape layer 1125 is removed, as shown in Fig. 11G. The encapsulant 1130 is cut in a manner that leaves a portion of the encapsulant over the previously exposed sidewalls of the cores 1105a of the components 1120a, 1120b, 1120c.

At block 1030, the ends of the singulated components 1120a, 1120b, 1120c may be plated to provide the first and second conductive ends 910a, 910g, as noted above. For example, the conductive epoxy layers 1130a and 1130b may be applied over the ends of the unified components 1120a, 1120b, and 1120c. The conductive epoxy layers 1130a and 1130b may cover some or all of the conductive protrusions 1110. In some embodiments, a brazeable nickel alloy finish can be provided on the conductive epoxy sides 1130a and 1130b.

As shown, the new fabrication methods can produce SMDs of various configurations. In addition, these methods can produce SMDs with small form factors that can maintain more hold currents than those manufactured using conventional processes. For example, the operations described in FIG. 10 may be tailored to some extent to fabricate SMDs, such as those shown in FIGS. 7 and 8. It should be understood by those skilled in the art that while the methods for fabricating SMDs and SMDs are described with reference to specific embodiments, various changes may be made and equivalents may be substituted without departing from the scope of the claims herein Will be. Many other modifications will tailor certain situations or materials to teachings that do not depart from the scope of the claims. Thus, it is intended that specific embodiments disclosed in which the method for fabricating SMDs and SMDs are disclosed, but not limit any embodiment within the scope of the claims.

100: mounting device
105a: upper surface
105b: bottom surface
110a: first end
110b: second end
112: conductive clip
115a: first contact pad
115b: second contact pad
120: Core device
120a: upper surface
120b: bottom surface
122a: first end
122b: second end
124a, 124b: conductive layer
125: Capsule
300:
305: Core device
310: Lead frame
315a, 315b: contact pad
400: Mold system
405: Plunger
407: encapsulating material
408: Frasperpot
410a:
410b: Drag
415: Ejector pin
418:

Claims (17)

Core device;
A portion of the lead frame attached to the core device; And
A capsule encapsulating at least a part of the core device and a part of the lead frame;
Lt; / RTI >
Wherein said encapsulant corresponds to a cured version of a liquid epoxy and has an oxygen permeability of less than about 0.4 cm < ³ > .mm / m < ² >
The method according to claim 1,
Wherein the encapsulant corresponds to a thermosetting epoxy, and in particular the epoxy has a viscosity between about 1500 cps and 3000 cps prior to curing.
3. The method of claim 2,
Wherein the epoxy comprises between about 10 and 50 weight percent filler content.
The method according to claim 1,
The lead frame defines first and second contact pads, and preferably the first contact pads are in electrical contact with the first end of the core device, And a conductive clipping wrap to thereby electrically couple the second contact pad to a second end of the core device.
The method according to claim 1,
Wherein the at least one core device is a positive-temperature-coefficient (PTC) device.
A method of manufacturing a surface mount apparatus according to claim 1,
Providing at least one core device and at least one leadframe;
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 leadframe within the capsule,
Lt; / RTI >
Wherein the encapsulant comprises a liquid epoxy that when cured has an oxygen permeability of less than about 0.4 cm ³ · mm / m ² · atm · day.
The method according to claim 6,
Encapsulating at least a portion of the at least one core device within the capsule and a portion of the at least one leadframe includes inserting the capsule around at least a portion of the at least one core device and a portion of the at least one leadframe, Transfer molding through a transfer molding system.
8. The method of claim 7,
Further comprising inserting the capsule into a pot of the transfer molding system and heating the pot between about 20 ° C and 30 ° C, preferably wherein the portion of the at least one lead frame and the at least one Inserting a plunger of the transfer molding system into the pot creating a pressure between about 150 psi and about 300 psi to force the capsule through the at least a portion of the core device of the core device and through the sprue of the molding system / RTI >
The method according to claim 6,
Wherein the transfer molding system comprises a cop and a drag, the drag comprising at least one hole having a height no greater than 20 [mu] m.
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;
A capsule covering at least a portion of an upper surface and a lower surface of the core;
Lt; / RTI >
Wherein the encapsulant has an oxygen permeability of less than about 0.4 cm ³ · mm / m ² · atm · day.
11. The method of claim 10,
The core is formed from a positive-temperature-coefficient (PTC) device, and the encapsulant is a thermosetting epoxy.
11. The method of claim 10,
Further comprising first and second conductive layers formed over the encapsulated ends of the core such that the first conductive layer is in electrical communication with at least one of the conductive protrusions formed on the top surface of the component, Wherein the conductive layer is in electrical communication with the at least one conductive protrusion formed on the lower surface of the component.
A method of manufacturing a surface mount apparatus according to claim 10,
Forming a plaque from the material;
Forming a plurality of conductive protrusions on an upper surface and a lower surface of the plaque;
Applying a liquid encapsulant over at least a portion of the upper surface of the plaque and over at least a portion of the lower surface;
Curing the liquid encapsulant, the cured capsule having an oxygen permeability of less than about 0.4 cm < ³ > mm / m < ² > And
Cutting through the cured capsule and plaque to provide a plurality of components;
Lt; / RTI >
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 surface and bottom surface of each component are cured Wherein the core of each component comprises a material.
14. The method of claim 13,
Wherein the plaque material corresponds to a positive-temperature-coefficient (PTC) device.
The method according to claim 1,
Wherein the encapsulant, when in a liquid state, corresponds to a thermosetting epoxy having a viscosity of about 1500 cps and 70,000 cps, preferably the epoxy comprises between 5 and 95 weight percent of the heavy content.
14. The method of claim 13,
After cutting, the method further comprises applying an additional liquid encapsulant to the sidewalls of each component exposed after cutting, and curing the liquid encapsulant such that the exposed sidewalls are completely covered with the cured capsule And preferably the cured additional capsule fills the space between the sidewalls of adjacent components joining the adjacent components to one another, the method further comprising the step of forming the intermediate section of the cured additional capsule RTI ID = 0.0 > 1, < / RTI >
14. The method of claim 13,
Wherein applying the liquid encapsulant comprises screen-printing the liquid encapsulant on the plaque, and preferably the screen used in screen-printing covers at least a portion of each of the plurality of conductive protrusions To prevent said liquid encapsulant.

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