Enhanced Cooling Package for Improved Thermal Management of Electrical Components

Abstract

An electrical component package includes a folded heat sink for enhancing heat dissipation. The internal components of the package include an electrical component, a lead frame, a conductive clip, and terminal leads, which are electrically and mechanically interconnected. The packaging material is used to form a molded part for encapsulating the internal components, and the molded part includes a recessed portion. The heat sink is provided for heat dissipation and includes a first flat portion extending from the lead frame, a second flat portion in a spaced relationship with the recessed portion of the molded part, and a folded portion integral with the first flat portion and the second flat portion and extending between the first flat portion and the second flat portion.

Description

Technical Field

[0001] The present application generally relates to a heatsink for the encapsulation of electrical components, and more particularly to a heatsink that achieves enhanced heat dissipation capabilities by extending the heatsink over one or more additional surfaces of the encapsulation. Background Art

[0002] Electrical components generate heat during normal operation and must be continuously cooled to ensure proper operation. Excessive heat can negatively impact the performance of an electrical system, as the parameter values of components typically vary with temperature. At particularly high temperatures, components may no longer meet specification requirements and may malfunction. As the size of these systems and devices continues to shrink, the size of their electrical components must also be reduced accordingly. Although the physical size of electrical systems and their components has decreased, the power requirements of these systems and the resulting heat generation have not necessarily decreased. Therefore, the heat generated by components must be carefully managed to maintain a safe and reliable operating temperature for the system.

[0003] Traditional semiconductor chip packages include positive and negative terminal leads on the bottom side of the package after the semiconductor device is mounted on a printed circuit board. During operation, the heat generated inside the chip will be mainly distributed vertically to the outside air through the heatsink located at the bottom. The heat flow efficiency is affected by various factors, including the thermal conductivity of the components used on the semiconductor chip, the thickness of the solder used, the quality of the heatsink, and other factors.

[0004] Accordingly, there is a desire to provide enhanced heat dissipation capabilities for electrical components such as semiconductors. There is also a desire to provide enhanced heat dissipation capabilities for electrical components that are suitable for small form factors and can be incorporated into existing systems. Additionally, there is a desire to provide enhanced heat dissipation capabilities for electrical components that can be manufactured economically, used durably, and operated efficiently. Summary of the Invention

[0005] Based on the above circumstances, the present disclosure is directed to extending a heatsink to create new paths for distributing the heat generated by electrical components such as semiconductors to the outside, so as to enhance cooling capabilities such as heat flow from the top or bottom side of the electrical component package.

[0006] To achieve this object, an electrical component package is provided, which includes a folded heat sink for enhancing heat dissipation. The internal components of the package may include a semiconductor die or chip, a lead frame, a conductive clip, and terminal leads, which are electrically and mechanically interconnected. The package material encapsulates the internal components, and the package material includes a recessed portion that is recessed into the surface of the package material. A heat sink is provided for heat dissipation and includes a first flat portion extending from the lead frame, a second flat portion spaced from the recessed portion of the package material, and a folded portion integral with the first flat portion and the second flat portion and extending between the first flat portion and the second flat portion.

[0007] In another aspect, a method for dissipating heat from an electrical component package is provided. The method includes positioning an electrical component, such as a semiconductor chip, on a lead frame, connecting a first end of a conductive clip to the top side of the electrical component, and connecting a second end of the conductive clip to a first terminal lead. The method includes encapsulating the semiconductor chip and the conductive clip, and at least a portion of the first terminal lead and the second terminal lead using a package material. A recessed portion is formed in the package material. The method includes forming a heat sink that includes a first flat portion extending from the lead frame, a second flat portion spaced from the recessed portion of the package material to define a gap therebetween, and a folded portion extending between the first flat portion and the second flat portion.

[0008] Other features that can be used alone or in various combinations with each other are described in detail below and in the claims. Description of the Drawings

[0009] The foregoing Summary of the Invention and the following Detailed Description will be best understood when read in conjunction with the accompanying drawings. In the drawings:

[0010] Figure 1 is an enlarged top perspective view of a first embodiment of an electrical component package, in which a portion of the heat sink is cut away to show the interrelationship of the internal components;

[0011] Figure 1A is an enlarged top perspective view of a first embodiment of an alternative heat sink that does not include a cut-out portion;

[0012] Figure 2 is an enlarged side view of a first embodiment of an electrical component package;

[0013] Figure 2A is an enlarged side view of a first embodiment of an electrical component package that includes an alternative package housing that does not include a recessed portion;

[0014] Figure 3 is an enlarged rear view of a first embodiment of an electrical component package;

[0015] Figure 4 is an enlarged top plan view of a first embodiment of an electrical component package;

[0016] Figure 5 is an enlarged top perspective view of a first embodiment of an electrical component package;

[0017] Figure 6 is an enlarged bottom perspective view of a first embodiment of an electrical component package;

[0018] Figure 7 is an enlarged top perspective view of a second embodiment of an electrical component package, in which a part of the heat sink is cut away to show the interrelationship of internal components;

[0019] Figure 7A is an enlarged top perspective view of a second embodiment of an electrical component package including an optional heat sink without a cutout portion;

[0020] Figure 8 is an enlarged side view of a second embodiment of an electrical component package;

[0021] Figure 8A is an enlarged side view of a second embodiment of an electrical component package including an optional package housing without a recessed portion;

[0022] Figure 8B is an enlarged rear view of a second embodiment of an electrical component package;

[0023] Figure 9 is an enlarged top plan sectional view of a second embodiment of an electrical component package;

[0024] Figure 10 is an enlarged top plan view of a second embodiment of an electrical component package;

[0025] Figure 11 is an enlarged bottom plan view of a second embodiment of an electrical component package;

[0026] Figure 12 is an enlarged bottom plan view of a second embodiment of an electrical component package in which the encapsulation is removed;

[0027] Figure 13 is an enlarged side view of an electrical component package showing the manner in which the heat sink is formed in a folded configuration;

[0028] Figure 14 is a flow chart showing an example of a method for manufacturing an electrical component package;

[0029] Figure 15 is an enlarged side view of an electrical component package mounted to a printed circuit board, showing a manner for dissipating heat from the electrical component package;

[0030] Figure 16 is an enlarged side view of a third embodiment of the electrical component package;

[0031] Figure 17 is an enlarged perspective view of an external heat sink mounted to the electrical component package; and

[0032] Figure 18 is an enlarged rear view of an external heat sink mounted to the electrical component package. DETAILED DESCRIPTION

[0033] In the following description, certain terms are used for convenience only and are not limiting. The terms "top side", "bottom side", "first lateral side", "second lateral side", "front end", and "rear end" designate the directions of reference in the drawings. The following description provides specific details in order to thoroughly understand the embodiments of the electrical component package and the processes for forming the electrical component package, which includes a heat sink having a folded configuration to enhance heat dissipation. Well-known structures and functions are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments described herein. The cut-away portions shown in the figures are for explanatory, illustrative, and demonstrative purposes only and are not intended to imply that the elements themselves will be cut-away in their final fabrication. Terms such as "substantially" or "approximately" are intended to include a tolerance of + / - 10% of the indicated value or the tolerance of the specified shape.

[0034] Now referring to Figures 1 to 6 , a first embodiment of an electrical component package 100 is shown. The electrical component package 100 can be generally rectangular in shape and can include a top side 110( Figure 2 ), a bottom side 114( Figure 2 ), a front end 118( Figure 2 ), a rear end 122( Figure 2 ), a first lateral side 126( Figure 1 ), and a second lateral side 130( Figure 1 ). The electrical component package 100 can be arranged for mounting to the surface of a printed circuit board, as best shown in Figure 15 . In this first embodiment 100, the electrical component package 100 includes a centrally located electrical or electronic component in the form of a die or chip 134 such as a semiconductor chip, which can have a generally square or rectangular configuration, having an upward-facing positive side 134a and a downward-facing negative side 134b( Figure 2)。In this embodiment, the negative side 134b can be attached and bonded to a lead frame 138 extending along the bottom side 114 of the electrical component package 100. For example, the die or chip 134 can be a two-terminal device such as a diode, or can be other types of electronic devices suitable for inclusion in an electrical component package. The bottom surface 134b of the die or chip 134 can be attached to the upper surface of the lead frame 138 using any suitable conductive material 142 (including but not limited to solder paste, wire solder, conductive adhesive, or sintered paste). In this way, an electrical contact is established between the lead frame 138 and the electrodes on the negative side 134b of the die or chip 134. As Figure 1 and Figure 4 best shown, the lead frame 138 can be in the form of a thin flat strip, which can be generally rectangular in shape and extends from a first lateral side 126 substantially across the entire width of the electrical component package 100 to a second lateral side 130. The lead frame 130 can also extend substantially all the way to the rear end 122 of the electrical component package 100. The lead frame 138 can be formed of any suitable conductive material, such as copper (Cu), aluminum (Al), nickel, titanium (Ti), or alloys based on these metals.

[0035] A heat sink 146 having a generally rectangular and folded configuration is provided. The heat sink 146 can initially be provided as a thin flat strip extending from the lead frame 138 towards the rear end 122 of the electrical component package 100. As used herein, "flat" means "substantially flat", i.e., within normal manufacturing tolerances. As the heat sink 146 extends from the lead frame 138 towards the rear end 122 of the electrical component package 100, it can be formed into a folded configuration and extends along the top side 110 of the electrical component package 100 to a free end 146c.

[0036] Specifically, the heat sink 146 may include a first flat portion 146a that extends from the lead frame 138 along the bottom side 114 of the electrical component package 100 toward the rear end 122 of the electrical component package 100. Once reaching the rear end 122, the heat sink 146 may be bent at a first corner 150 by an angle of approximately 90 degrees and extend upward a predetermined distance to a second corner 154 located on the top side 110 of the electrical component package 100. Once reaching the second corner 154, the heat sink 146 may be bent again by an angle of approximately 90 degrees and extend along a second flat portion 146b along the top side 110 a predetermined distance to a free end 146c, such that the heat sink 146 has a folded appearance. It should be understood that the folded appearance created by bending the heat sink 146 at the two corners 150 and 154 is illustrative of a preferred embodiment and is merely exemplary, and other shapes and configurations can be envisioned to obtain a folded appearance, including, for example, arcuate, semi-circular, or other shapes. The first flat portion 146a and the second flat portion 146b may be substantially parallel to each other.

[0037] At the rear end 122 of the electrical component package 100, the heat sink 146 may include a cutout portion 158 to define opposing arms 160a and 160b that extend from the bottom side 114 to the top side 110. In a first embodiment, although the cutout portion 158 is shown as having a generally rectangular shape, other shapes can be envisioned. One purpose of the cutout portion 158 may be to reduce the stress accumulated during the formation of the corners 150, 154 to prevent breakage of the heat sink 146. By providing the cutout portion 158, the amount of material in the corners 150, 154 region is greatly reduced, which facilitates bending of the heat sink material to form the corners 150, 154, thereby reducing the likelihood of abnormal bending or breakage of the heat sink 146 at the corners 150, 154 during formation. Another purpose of the cutout portion 158 is to allow enhanced air flow to dissipate heat from both sides of the second flat portion 146b. It should be understood that the cutout portion 158 is an optional feature of the heat sink 146, and the cutout portion 158 may or may not be included in the heat sink 146. As Figure 1A best shown, the cutout portion (shown as 158 in Figure 1 is not included as a feature of the heat sink 146'. Thus, Figure 1A the heat sink 146' can be formed to have a continuous, unbroken wall that extends along a portion of the rear end 122 of the device. In other respects, Figure 1A the embodiments of Figure 1 may have the same configuration as the embodiments of

[0038] The heat sink 146 may include one or more enclosed through - holes 162, one or more open through - holes 163, and a V - shaped notch 164 extending from the first lateral side 126 to the second lateral side 130. These features are included in the heat sink 146 to receive epoxy resin or other suitable encapsulating materials therein during a molding process (described below) to hold a portion of the heat sink 146 in the encapsulating material, thereby enhancing the bonding ability of the encapsulating material to the heat sink 146 and reducing the risk of peeling.

[0039] Now referring Figure 5 , although the free end 146c of the heat sink 146 is shown as having pointed corners 170, it should be understood that these corners 170 may be rounded or curved to some extent or slightly. Acceptable metals for forming the heat sink 146 may be copper, aluminum, platinum, or other metals known in the art as heat sinks. The thickness of the heat sink 146 is determined based on design considerations such as the electrical performance, thermal capacity, cost, and size requirements of the product. The approximate range of the preferred thickness of the heat sink 146 is from 0.2 millimeters to 2.0 millimeters. The generally rectangular shape of the heat sink 146 is illustrative of the preferred embodiment, and other configurations can be envisioned to maximize the use of the available space on the electrical component package 100, thereby maximizing heat dissipation. Also, it should be understood that although the heat sink 146 is shown in the figures as a single, integral body, the heat sink 146 may be provided as separate or discrete parts, formed of the same or different materials, and joined together to form the final heat sink 146.

[0040] Referring Figure 1 , Figure 2 and Figure 4 , a clip - on member 174 is provided to connect the positive side 134a of the die or chip 134 to the terminal leads 178 and 182. The electrical component package 100 includes a package housing 186 (shown in dashed lines) for protecting the components of the semiconductor package from moisture intrusion and mechanical damage. The terminal leads 178 and 182 are shown as being spaced apart from each other by a predetermined distance, and each terminal lead 178 includes a portion within the package housing 186 and another portion outside the package housing 186 to provide electrical connection between the electrical component package 100 and a printed circuit board 190 ( Figure 15 ).

[0041] Specifically, the clip member 174 may include a free end 174a which is arranged to be bonded to the top surface or the positive side 134a of the die or chip 134 using any suitable conductive material 142 (including but not limited to solder paste, solder wire, conductive adhesive, or sintering paste). As the clip member 174 extends from the free end 174a towards the front end 118 of the package 100, the clip member 174 may include a raised section 174b which serves as a bridge between the die or chip 134 and the terminal leads 178 and 182. As Figure 1 best shown, the clip member 174 includes branch portions 174c and 174d which extend in opposite directions and are bent towards the terminal leads so as to be connected to the terminal leads. Any suitable conductive material 184 such as solder paste, solder wire, conductive adhesive, or sintering paste can be used to physically connect the branches 174c and 174d to the terminal leads 178 and 182 so as to provide an electrical connection between the die or chip 134 and the terminal leads 178 and 182. In this first embodiment, since both the terminal leads 178 and 182 are connected to the positive side 134a of the die or chip 134, these terminal leads are positive terminal leads.

[0042] As Figure 1 and Figure 2 best shown, each of the terminal leads 178 and 182 includes an upper generally horizontal portion 178a, 182a, a lower generally horizontal free end 178b, 182b, and a bent portion 178c, 182c provided therebetween. As Figure 15 best shown, the lower generally horizontal free ends 178b, 182b of the terminal leads 178, 182 are arranged to contact the top side of the printed circuit board 190 when the electrical component package 100 is mounted to the printed circuit board 190.

[0043] The clip member 174 may be formed of any suitable material such as aluminum, copper, silver, gold, or a metal alloy. As an alternative to the clip member 174, a wire or strip may be utilized which is formed of a suitable material such as aluminum, copper, silver, gold, or a metal alloy. The electrical component package 100 may include a central pin 185 which is centrally disposed between the terminal leads 178 and 182. As Figure 2 best shown, the central pin 185 extends from its free end which is bent downwardly to be coupled to the lead frame 138. The central pin 185 may be in the same plane as the upper generally horizontal portions 178a, 182a of the terminal leads 178 and 182.

[0044] As Figure 2 and Figure 3As best shown, after the clamping member 174 is bonded in place, an encapsulation housing 186 can be formed around the components of the semiconductor package to prevent moisture intrusion and mechanical damage. Specifically, the entire die 134, lead frame 138, a portion of the heat sink 146, the entire clamping member 174, conductive materials 142, 184, and a portion of the lead terminals 178 and 182 can be wrapped or encapsulated in an epoxy resin or other compound suitable for encapsulating electrical components. As Figure 2 As best shown, the encapsulation housing 186 can be formed to include a recessed portion 188. The second flat portion 146b of the heat sink 146 can extend within the recessed portion 188 and be positioned therein to maintain a distance or gap 210 between the second flat portion 146b of the heat sink 146 and the recessed portion 188 of the encapsulation housing 186, so as to increase heat dissipation during the operation of the electrical component encapsulation. The gap 210 can also be used to provide space and prevent contact between the encapsulation housing 186 and the second flat portion 146b positioned adjacent to the encapsulation housing 186, thereby avoiding damage to the encapsulation housing 186. The second flat portion 146b can preferably extend together with the recessed portion 188 and cover the recessed portion 188. In addition, preferably there can be a small gap between the free end 146c of the heat sink 146 and the vertical edge of the recessed portion 188 adjacent to the free end 146c. Once the compound has cured, it can be trimmed to remove the burrs generated during the molding process. In addition, as part of the trimming process, the useless bars on the lead frame 138 can be removed.

[0045] The depth of the recessed portion 188 is preferably between 80% and 150% of the thickness of the second flat portion 146b of the heat sink 146. More preferably, the depth is between 100% and 120% of the thickness. In addition, the distance or gap 210 is preferably in the range of 30% to 80% of the thickness of the second flat portion 146b of the heat sink 146. More preferably, the distance or gap 210 is between 40% and 60% of the thickness. The size of the gap 210 affects the overall thickness of the electrical component encapsulation 100. Therefore, a smaller gap 210 is preferred, for example, greater than 0 mm.

[0046] It should be understood that the recessed portion 188 is an optional feature of the encapsulation housing 186, and the recessed portion 188 may or may not be included in the encapsulation housing 186. As Figure 2A As best shown, the encapsulation housing 186 is shown as not including such a recessed portion. In this configuration, for the reasons described above, the second flat portion 146b of the heat sink 146 can be positioned to maintain a distance or gap 210 between the second flat portion 146b of the heat sink 146 and the encapsulation housing 186.

[0047] Once the encapsulation housing 186 is trimmed, suitable forming tools can be used to form the terminal leads 178, 182 from a substantially straight configuration into a bent configuration including upper generally horizontal portions 178a, 182a, lower generally horizontal free ends 178b, 182b, and bent portions 178c, 182c disposed therebetween.

[0048] As Figure 1 , Figure 2 and Figure 13 best shown, the formation of the heat sink 146 from a straight strip extending from the lead frame 138 to the free end 146c of the heat sink 146 to its folded configuration is illustrated in a series of progressive steps. As used herein, "flat" or "flattened" means "substantially flat" or "substantially flattened", i.e., within normal manufacturing tolerances. As Figure 13 best shown, the heat sink 146 can be folded in several steps as represented by step 1305, step 1310, step 1315, step 1320, step 1325, and step 1330 using suitable forming tools to form corners 150, 154. Step 1305 shows the initial generally flat configuration after encapsulation. Step 1310 shows the initial upward folding of the second flat portion 146b and the arms 160a and 160b. Step 1315 shows the partial formation of the two corners 150, 154 as the bending continues. Steps 1320 and 1325 show the further bending of the second flat portion 146b toward a position parallel to but offset from the first flat portion 146a as the corners 150, 154 move to their final positions, and step 1330 shows the final position where the second flat portion 146b is partially located in the recessed portion 188 of the encapsulation housing 186. Once the formation is complete, as described in detail above, the heat sink 146 extends from the lead frame 138 toward the rear end 122 on the bottom side and is flipped onto the top side 110 of the electrical component package 100.

[0049] Figure 14FIG. 0 is a flowchart showing an example of a method for forming an electrical component package having a folded heat sink. At block 1405, in the "die bond" step, the bottom surface of die or chip 134 is attached and bonded to lead frame 138 using any suitable conductive material 142 as described above. The bottom surface of die or chip 134 can be the negative side of the die or chip, or alternatively can be the positive side of the die or chip, if this is appropriate for the device. At block 1410, in the "clip bond" step, clip 174 having a free end 174a is bonded to the top surface of die or chip 134 using a suitable conductive material as described above. As clip 174 extends from its free end 174a, it branches as described above and can be bonded to two terminal leads 178 and 182 using a suitable conductive material. In other embodiments, clip 174 can be bonded to only one of terminal leads 178, 182, with the other terminal lead contacting the lead frame. At block 1415, in the "wire / ribbon bond" step, as an alternative to clip 174, wire or ribbon can be employed. At block 1420, in the "molding" step, encapsulation housing 186 can be molded around all or a portion of the components of electrical component package 100 to prevent moisture ingress and mechanical damage. At block 1425, in the "trim" step, the encapsulation housing can be trimmed. At block 1430, in the "plating" step, electrical component package 100 can be plated. At block 1435, in the "form and singulation" (folding the heat sink) step, as heat sink 146 extends from lead frame 138, heat sink 146 can be folded from the bottom of the electrical component package to the top of the electrical component package using, for example, a suitable forming tool. Additionally, terminal leads 178 and 182 can be formed as described above to include substantially horizontal free ends 178b and 182b to contact the surface of printed circuit board 190 ( Figure 15 ) when the electrical component package is mounted to printed circuit board 190. At block 1440, in the "test" step, the finished electrical component package 100 including the folded heat sink can be tested.

[0050] Now refer to Figure 15, once the completed electrical component package 100 is mounted onto the surface of the printed circuit board 190, the generally horizontal free ends of the terminal leads 178b, 182b are arranged to contact the top surface of the printed circuit board 190 and are used for heat dissipation from the electrical component package 100 as indicated by arrow 194. Similarly, a portion of the heat sink 146 and the lead frame 138 are arranged to contact the top surface of the printed circuit board 190 to provide heat dissipation from the electrical component package 100 as indicated by arrow 198. Additionally, when the heat sink 146 turns around the corners 150 and 154 and extends across the top side 110 of the package 100, the heat sink 146 dissipates heat away from the package 100 in the directions indicated by arrows 202 and 206. The gap 210 also allows air flow for heat dissipation from the heat sink 146.

[0051] Now referring to Figures 7 to 12 , a second embodiment of an electrical component package 300 is shown. Similar to the first embodiment 100, the electrical component package 300 includes a top side 304, a bottom side 308, a front end 312, a rear end 316, a first lateral side 320, and a second lateral side 324. In this second embodiment, a die or chip 332 is mounted to a lead frame 334 with the positive side 332a of the die or chip 332 facing upward and the negative side 332b of the die or chip 332 facing downward, where the die or chip 332 is attached to the lead frame 334 by bonding as discussed in the first embodiment. Similar to the first embodiment, the die or chip 332 can be a two-terminal device such as a diode, and the bottom surface or negative side of the die or chip 332 can be attached to the top surface of the lead frame 334 using any suitable conductive material 336 as discussed above to establish electrical contact and thus form a first terminal.

[0052] In the second embodiment, the clip 340 has a generally reverse S-shaped configuration that includes a first free end 340a arranged for bonding to the top surface 332a or positive side of the die or chip 332. The clip 340 may also include a raised section 340b that serves as a bridge between the die or chip 332 and the terminal lead 344. As Figure 7 and Figure 8 best shown, at the second free end 340c of the clip 340, the clip 340 is arranged to be connected to the terminal lead 344 by bonding as discussed in the first embodiment to provide an electrical connection between the die or chip 332 and the terminal 344. Thus, the terminal lead 344 is a positive terminal lead formed by its connection to the positive side of the die or chip 332. As Figure 7 and 8As best shown, each terminal lead 344, 346 includes an upper generally horizontal portion 344a, 346a, a lower generally horizontal free end 344b, 346b, and a bent portion 344c, 346c disposed therebetween.

[0053] Similar to the first embodiment, a heat sink 352 having a generally rectangular and folded configuration is provided. As Figures 7 to 9 best shown, the heat sink 352 can extend rearward from the lead frame 334 toward the rear end 316 of the semiconductor package 300. When the heat sink 352 extends toward the rear end 316 of the semiconductor package 300, it can be formed in a folded configuration and extend along the top side 304 of the semiconductor package 300 to the free end 352c. Specifically, as Figure 8 and Figure 8B best shown, the heat sink 352 can include a first flat portion 352a that extends from the lead frame 334 along the bottom side 308 of the electrical component package 300 toward the rear end 316 of the electrical component package 300. Once reaching the rear end 316, the heat sink 352 can be bent at the first corner 356 at an angle of approximately 90 degrees and extend upward from the first corner 356 a predetermined distance to a second corner 360 located on the top side 304 of the electrical component package 300. Once reaching the second corner 360, the heat sink 352 can be bent or turned again at an angle of approximately 90 degrees and extend along the second flat portion 352b from the second corner 360 a predetermined distance to the free end 352c of the heat sink 352 along the top side 304 as it approaches the front end 312 of the semiconductor package 300, giving the heat sink 352 a folded appearance. It should be understood that the folded appearance created by the bends of the heat sink 352 at the two corners 356 and 360 is illustrative of the preferred embodiment and is merely exemplary, and other shapes and configurations can be envisioned to obtain a folded appearance, including, for example, arcuate, semi-circular, or other shapes.

[0054] As Figure 7 、 Figure 8B and Figures 9 to 12 shown, the second embodiment of the electrical component package 300 can include a large cutout portion 364 provided for the purposes discussed in connection with the first embodiment, namely, to reduce stress and increase heat dissipation. The cutout portion 364 defines opposing arms 366a and 366b that extend from the bottom side 308 to the top side 304. It should be understood that the cutout portion 364 is an optional feature of the heat sink 352, and the heat sink may or may not include this cutout portion 364. For example, as Figure 7A best shown, the cutout portion (labeled 364 in Figure 7 ) is not included as a feature of the heat sink 352' of the electrical component package 300 of the second embodiment. Thus, Figure 7AThe heat sink 352' can be formed to have a continuous, unbroken wall extending along a portion of the rear end 316 of the device. In other respects, Figure 7A the embodiment of Figure 7 can have the same configuration as the

[0055] Similar to the first embodiment, the heat sink 352 can include one or more closed through-holes 368 and one or more open through-holes 370, which are arranged to receive epoxy resin or other suitable encapsulating material therein during the molding process to hold the heat sink 352 within the encapsulating material. Additionally, similar to the first embodiment, V-shaped notches 372 can be provided to reduce stress accumulation and prevent breakage during the formation of the folded portion. The V-shaped notches 372 are shown extending from the first lateral side 320 to the second lateral side 324.

[0056] The folded heat sink 352 can be a negative heat sink formed by its connection to the negative side 332b of the die or chip 332 through the lead frame 334. Now referring to Figure 7 and Figure 8 , the lead frame 334 is shown contacting the negative side 332b of the die or chip 332 and connected to the terminal lead 346, which is a negative terminal lead formed by its connection to the negative side 332b of the die or chip 332.

[0057] As an alternative in this embodiment, the die or chip 332 can be mounted to the lead frame 334 with the positive side 332a of the die or chip facing down and bonded to the lead frame 334, and the negative side 332b of the die or chip facing up. In this mounting orientation, the terminal lead 344 will be a negative terminal lead formed by its connection to the negative side 332b of the die or chip 332, and the heat sink 352 will be a positive heat sink formed by its connection to the positive side 332a of the die or chip 332. As mentioned in the first embodiment, as an alternative to the clip 340, a wire or strip formed of a suitable material as defined above can be utilized.

[0058] As best shown in Figure 7 and Figure 8 , similar to the first embodiment, after the clip 340 is bonded in place, a package housing 376 (shown in dashed lines) can be formed around the components of the semiconductor device to prevent moisture intrusion and mechanical damage. Specifically, the die 332, the lead frame 334, a portion of the heat sink 352, the clip 340, the conductive material 336, and portions of the terminal leads 344 and 346 can be wrapped or encapsulated in epoxy resin or other suitable compounds suitable for encapsulating electrical components 300. As Figure 8As best shown, the encapsulation housing 376 may include a recessed portion 378 having a configuration as described in the first embodiment. The second flat portion 352b of the heat sink 352 may extend within the recessed portion 378 of the encapsulation housing 376 to maintain a predetermined distance between the recessed portion 378 of the encapsulation housing 376 and the second flat portion 352b of the heat sink, thereby allowing for increased heat dissipation during operation of the electrical component package.

[0059] It should be understood that the recessed portion 378 is an optional feature of the encapsulation housing 376 and may or may not be included in the encapsulation housing 376. As Figure 8A best shown, the electrical component package of the second embodiment is shown to include an encapsulation housing 376 that does not include such a recessed portion. In such a configuration, the second flat portion 352b of the heat sink 352 may be positioned to maintain a certain distance or gap between the second flat portion 352b of the heat sink 352 and the encapsulation housing 376 for the reasons described above.

[0060] Similar to the first embodiment, the heat sink 352 can be formed from a flat strip into the corner portions 356 and 360 to the folded configuration in several steps as Figure 13 shown using a suitable forming tool. Once this forming is completed, the heat sink 352 extends from the bottom side and flips onto the top side of the electrical component package 300 as described in detail above. Additionally, as described in the first embodiment, using a suitable forming tool, the terminal leads 344 and 346 can be formed from a substantially straight configuration into a bent configuration including an upper substantially horizontal portion 344a, 346a, a lower substantially horizontal free end 344b, 346b, and a bent portion 344c, 346c disposed therebetween. In this way, the terminal leads 344, 346 can contact the surface of the printed circuit board when the completed electrical component package 300 is mounted to the printed circuit board 190 ( Figure 15 ).) for heat dissipation. As described in the first embodiment, the folded heat sink 352 can provide heat dissipation from the electrical component package 300 in the directions of arrows 198, 202, and 206.

[0061] Now referring to Figure 16, a side view of a third embodiment of the electrical component package 400 of the present invention is shown. In the first and second embodiments, the encapsulated electrical component is located near the bottom side of the package, and the heat sink extends from the bottom side and folds over to the top side. Different from the first and second embodiments, in this embodiment 400, the electrical component is located near the top side 404 of the semiconductor package, and the heat sink 452 extends from the top side and folds under the bottom side of the package housing 476 and at least partially into the recess 477 at the bottom side of the package housing 476. Similar to the first and second embodiments, the recess 477 is optional. The third embodiment 400 also includes a bottom side 408, a front end 412, and a rear end 416. The lead frame 434 extends across the top side 404 of the package 400, and the die or chip 432 is mounted to the bottom surface of the lead frame 434, where it is attached to the lead frame 434 by bonding using a suitable conductive material 436 as described above. The die or chip 432 can be a two-terminal device such as a diode. The clip 440 is similar to the clip 174 or 340 described above, and includes a first free end 440a that is arranged to be bonded to the bottom side of the die or chip 432 using a suitable conductive material 436. The clip 440 can include a trough section 440b that extends between the first free end 440a and the second free end 440c to connect the die or chip 432 to the terminal lead 444 as described in the previous two embodiments before bonding. The terminal lead 444 can include an upper generally horizontal portion 444a, a lower generally horizontal free end 444b, and a bent portion 444c disposed therebetween.

[0062] A heat sink 452 having a generally folded configuration is provided. The heat sink 452 is shown extending from the lead frame 434 at the top side 404 towards the rear end 416 of the package 400, where the heat sink 452 can be bent at a first corner 456 and extend downward a predetermined distance to a second corner 460, and can turn again and extend along the bottom side 408 of the package 400 a predetermined distance to the free end 452a of the heat sink 452, giving the heat sink 452 a folded appearance. Similar to the first and second embodiments, the third embodiment of the electrical component package 400 can include a cutout portion to define opposing arms extending from the top side 404 to the bottom side 408. Additionally, similar to the first and second embodiments, other features such as a V-shaped notch 472 can be included to reduce stress accumulation and prevent breakage during the formation of the fold. Also, the heat sink 452 can include one or more closed through-holes and one or more open through-holes 468 that are arranged to receive epoxy resin or other suitable encapsulation material therein during the molding process to hold the heat sink 452 within the encapsulation material.

[0063] As discussed in the first and second embodiments, die or chip 432 can be mounted to lead frame 434 such that the positive side of die or chip 432 contacts lead frame 434, or such that the negative side of die or chip 432 contacts lead frame 434. The mounting orientation of die or chip 432 on lead frame 434 will determine whether the folded heat sink is negative or positive. As previously mentioned, as an alternative to clip 440, a thread or strip formed of any of the suitable materials described above can be utilized.

[0064] As described in the first and second embodiments, after clip 440 has been bonded in place, a package housing 476 (shown in dashed lines) can be formed around the components of the semiconductor device to prevent moisture intrusion and mechanical damage. Package housing 476 can be formed to include a recessed portion 477 having the configuration described in the first embodiment.

[0065] Similar to the previous embodiments, for example, heat sink 452 can be formed from a flat strip in several steps using a suitable forming tool to form corners 456 and 460 to a folded configuration. Once this formation is complete, heat sink 452 can extend from the top side, bend at corners 456 and 460, and extend to be adjacent to and at least partially located within recessed portion 477. A predetermined distance or gap can be maintained between heat sink 452 and recessed portion 477 to allow for increased heat dissipation during operation of the electrical component package.

[0066] Now referring Figure 17 and Figure 18 , an external heat sink 500 is shown that is arranged for use in combination with any of the embodiments of the electrical component package described above. As best shown in these figures, for example, an embodiment of electrical component package 100 is shown as being disposed in contact with printed circuit board 190. An external heat sink 500 can be provided to supplement or enhance the conductive cooling and heat dissipation provided by heat sink 146 during operation of electrical component package 100, such as for high-power electrical components. The use of external heat sink 500 is optional such that if heat dissipation is not a problem for a particular electrical component package, the use of external heat sink 500 can be dispensed with. Additionally, details related to the design of external heat sink 500, including the dimensions and configuration shown in the figures, are merely exemplary and are presented for illustrative purposes only and are not intended to be limiting in any way.

[0067] In the figures, external heat sink 500 is shown positioned above electrical component package 100 and in contact with the top side 110 of its folded heat sink 146. External heat sink 500 can be formed of any suitable thermally conductive material, including suitable metals such as forged aluminum or impact-extruded aluminum.

[0068] The external heat sink 500 includes a mounting surface 504 for receiving heat from the top side 110 of the heat sink 146 of the electrical component package 100. The external heat sink 500 includes a plurality of heat radiation surfaces 508 for radiating the received heat to a coolant. The coolant may be in the form of a gas, such as ambient air, or may be a liquid. The heat radiation surfaces 508 may be formed as a plurality of parallel heat dissipation fins 512. The fins 512 may extend upward a predetermined distance from a central region 514 located above the mounting surface 504. The fins 512 may extend away from the mounting surface 504 in a generally vertical direction, or in a direction perpendicular to the surface of the printed circuit board 190. The heat radiation surfaces 508 may also be formed as a plurality of heat dissipation fins 516, which may extend downward from the central region 514 to approach but not contact the top surface of the printed circuit board 190. The heat radiation surfaces 508 may also be formed as a plurality of heat dissipation grooves 518 formed in the central region 514. The combination of these features makes the surface area of the heat radiation surface 508 larger than the surface area of the mounting surface 504. The surface area of the heat radiation surface 508 may preferably be two or more times, preferably at least four times, the surface area of the mounting surface 504. In addition, a major portion of the fins 512 is located within the footprint of the mounting surface 504. In other words, the horizontal extent of the fins 512 is substantially within the horizontal extent of the mounting surface 504. The external heat sink 500 may include additional features such as a cutout portion 520.

[0069] It should be understood that the heat sink according to the present invention may include one or more cutouts, additional openings, or no cutouts or additional openings, or variations in the shape and size of any cutouts or openings.

[0070] It should be understood that the above is presented by way of example rather than by way of any limitation. It is contemplated that various alternatives and modifications may be made to the embodiments without departing from the spirit and scope of the present invention. Thus, the present invention has been described in detail, and it should be understood and will be apparent to those skilled in the art that many physical changes (only some of which are illustrated in the specific embodiments of the present invention) may be made without changing the concepts and principles embodied herein. It should also be understood that many embodiments including only a part of the preferred embodiments are feasible, and with respect to those parts, they do not change the concepts and principles embodied herein. This embodiment and the optional configurations are therefore to be regarded in all respects as illustrative and / or exemplary, and not restrictive, the scope of the present invention being indicated by the appended claims rather than by the foregoing description, and all alternative embodiments and changes falling within the meaning and scope of the equivalents of the said claims are therefore embraced therein.

Claims

1. An electrical component package arranged for mounting on a printed circuit board, the electrical component package comprising: An electrical component having a first side with at least one electrical contact and a second side opposite the first side and having at least one electrical contact; A lead frame arranged for receiving the second side of the electrical component and electrically connected to the second side of the electrical component; A conductive clip having a first end electrically connected to the first side of the electrical component, and the conductive clip extending from the first end for electrical connection to at least a first terminal lead; A second terminal lead extending from the electrical component package; A packaging material encapsulating the electrical component and the conductive clip and at least a portion of the first terminal lead and the second terminal lead; And A heat sink comprising a first flat portion extending from the lead frame, a second flat portion spaced from the packaging material, and a folded portion extending between the first flat portion and the second flat portion; Wherein the electrical component package includes a top side and a bottom side, the lead frame is arranged along the top side or the bottom side of the electrical component package, and the first flat portion of the heat sink extends from the lead frame along the top side or the bottom side of the electrical component package.

2. The electrical component package according to claim 1, wherein The folded portion includes a cutout portion to define opposing arms extending from the first flat portion to the second flat portion.

3. The electrical component package according to claim 1, characterized in that, The folded portion is integral with the first flat portion and the second flat portion.

4. The electrical component package according to claim 1, characterized in that, The heat sink includes at least one through hole for receiving the packaging material.

5. The electrical component package according to claim 4, wherein The at least one through hole includes a closed through hole.

6. The electrical component package according to claim 1, wherein The first terminal lead is a positive terminal lead.

7. The electrical component package according to claim 1, wherein The conductive clip is electrically connected to the second terminal lead, and both the first terminal lead and the second terminal lead are positive terminal leads.

8. The electrical component package according to claim 1, wherein The first terminal lead is electrically connected to the conductive clip and is a positive terminal lead, the second terminal lead is electrically connected to the lead frame and is a negative terminal lead.

9. The electrical component package according to claim 1, characterized in that, The first terminal lead and the second terminal lead extend to a position adapted to contact the printed circuit board.

10. The electrical component package according to claim 1, wherein, The first side of the electrical component is positive, and the second side of the electrical component is negative, and the heat sink is part of the negative pole.

11. The electrical component package according to claim 1, characterized in that, The first side of the electrical component is negative, and the second side of the electrical component is positive, and the heat sink is part of the positive pole.

12. The electrical component package according to claim 1, characterized in that, The electrical component includes a diode.

13. The electrical component package according to claim 1, characterized in that, The second flat portion of the heat sink is generally rectangular in shape.

14. The electrical component package according to claim 1, characterized in that, The electrical component package further includes a central pin located between the first terminal lead and the second terminal lead.

15. The electrical component package according to claim 1, characterized in that, The first flat portion and the second flat portion of the heat sink are substantially parallel.

16. The electrical component package according to claim 1, characterized in that, The lead frame extends along the bottom side of the electrical component package, the first flat portion of the heat sink extends from the lead frame along the bottom side of the electrical component package, and the second flat portion of the heat sink extends from the folded portion along the top side of the electrical component package.

17. The electrical component package according to claim 1, wherein, The lead frame extends along the top side of the electrical component package, the first flat portion of the heat sink extends from the lead frame along the top side of the electrical component package, and the second flat portion of the heat sink extends from the folded portion along the bottom side of the electrical component package.

18. The electrical component package according to claim 1, wherein, The electrical component is a semiconductor chip.

19. The electrical component package according to claim 1, wherein, The electrical component package further includes an external heat sink, which is arranged to be positioned above the electrical component package and contact the second flat portion of the heat sink of the electrical component package.

20. The electrical component package according to claim 19, characterized in that, The external heat sink is formed of a thermally conductive material.

21. The electrical component package according to claim 1, characterized in that, The encapsulating material includes a recessed portion.

22. A method for dissipating heat from an electrical component package, the method comprising: a. providing an electrical component having a first side and a second side opposite the first side; b. positioning the second side of the electrical component on a lead frame; c. providing a conductive clip having a first end and a second end; d. connecting the first end of the conductive clip to the first side of the electrical component and connecting the second end of the conductive clip to at least a first terminal lead; e. providing a second terminal lead positioned in the electrical component package; f. encapsulating the electrical component and the conductive clip and at least a portion of the first terminal lead and the second terminal lead using an encapsulating material; g. forming a recessed portion that is recessed into the surface of the encapsulating material; and h. forming a heat sink, the heat sink including a first flat portion extending from the lead frame, a second flat portion positioned adjacent to the recessed portion of the encapsulating material, and a folded portion extending between the first flat portion and the second flat portion.

23. The method according to claim 22, wherein The method further includes the step of electrically connecting the conductive clip to the second terminal lead.

24. The method according to claim 22, wherein The method further includes the step of forming a cut in the folded portion of the heat sink to define opposing arms extending from the first flat portion to the second flat portion.

25. The method according to claim 22, wherein The step of forming the heat sink further includes the steps of bending the folded portion to a position substantially transverse to the first flat portion and bending the second flat portion to a position substantially transverse to the folded portion and at least partially extending into the recessed portion.

26. The method according to claim 22, wherein The second flat portion includes a thickness, and the depth of the recessed portion is between 100% and 120% of the thickness of the second flat portion.

27. The method according to claim 22, wherein The second flat portion includes a thickness and is positioned to maintain a gap with the recessed portion, the gap being between 30% and 80% of the thickness of the second flat portion.

28. The method according to claim 22, characterized in that, The electrical component package includes a top side and a bottom side, the lead frame is disposed along the top side or the bottom side of the electrical component package, and the first flat portion of the heat sink extends from the lead frame along the top side or the bottom side of the electrical component package.

29. The method according to claim 28, wherein The first flat portion of the heat sink extends from the lead frame along the bottom side of the electrical component package, and the second flat portion of the heat sink extends from the folded portion along the top side of the electrical component package.

30. The method according to claim 28, wherein The first flat portion of the heat sink extends from the lead frame along the top side of the electrical component package, and the second flat portion of the heat sink extends from the folded portion along the bottom side of the electrical component package.

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