Cooling assemblies for electronic devices

According to some aspects of the present disclosure, cooling assemblies for electronic devices are disclosed. Example cooling assemblies include a circuit board having a first surface and a second surface opposite the first surface, a first set of electronic devices, a second set of electronic devices, and a third set of electronic devices. Each set includes at least two electronic devices electrically coupled in parallel and disposed on the first surface of the circuit board. At least one of the electronic devices of the first set is adjacent one of the electronic devices of the second set and is adjacent one of the electronic devices of the third set. The cooling assembly further includes a heat sink disposed on the second surface of the circuit board. The heat sink is in thermal contact with the first set, the second set, and the third set of electronic devices.

FIELD

The present disclosure relates to cooling assemblies for electronic devices.

BACKGROUND

Electronic devices are commonly used on circuit boards in electric power supplies. Heat sinks are typically used to dissipate unwanted heat generated by the electronic devices.

SUMMARY

According to one aspect of the present disclosure, a cooling assembly for electronic devices includes a circuit board having a first surface and a second surface opposite the first surface, a first set of electronic devices, a second set of electronic devices, and a third set of electronic devices. Each set includes at least two electronic devices electrically coupled in parallel and disposed on the first surface of the circuit board. At least one of the electronic devices of the first set is adjacent one of the electronic devices of the second set and is adjacent one of the electronic devices of the third set. The cooling assembly further includes a heat sink disposed on the second surface of the circuit board. The heat sink is in thermal contact with the first set of electronic devices, the second set of electronic devices, and the third set of electronic devices.

According to another aspect of the present disclosure, a cooling assembly for electronic devices includes a circuit board having a first surface and a second surface opposite the first surface, a first set of electronic devices, a second set of electronic devices, and a third set of electronic devices. Each set includes at least two electronic devices electrically coupled in parallel and disposed on the first surface of the circuit board. The cooling assembly further includes a heat sink disposed on the second surface of the circuit board. The heat sink includes a first heat sink portion in thermal contact with the first set of electronic devices, a second heat sink portion in thermal contact with the second set of electronic devices, a third heat sink portion in thermal contact with the third set of electronic devices, a fin structure in thermal contact with the three heat sink portions, and an electrical insulation layer disposed between the fin structure and the three heat sink portions to electrically isolate the three heat sink portions from one another.

Further aspects and areas of applicability will become apparent from the description provided herein. It should be understood that various aspects and features of this disclosure may be implemented individually or in combination with one or more other aspects or features. It should also be understood that the description and specific examples herein are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Corresponding reference numerals indicate corresponding features throughout the several views of the drawings.

DETAILED DESCRIPTION

A cooling assembly for electronic devices according to one example embodiment of the present disclosure is illustrated inFIG. 1and indicated generally by reference number100. As shown inFIG. 1, the cooling assembly100includes a circuit board102(e.g., printed circuit board, etc.) having a first surface103and a second surface (not shown inFIG. 1) opposite the first surface103.

The cooling assembly100includes a first set106of electronic devices104, a second set108of electronic devices104, and a third set110of electronic devices104. As shown inFIG. 1, each set includes two electronic devices104, although other embodiments could include more than two electronic devices104per set (e.g., three per set, etc.). Within each set, the electronic devices104are coupled in parallel with one another (e.g., via a circuit board trace, wire, etc.; not shown).

Some of the electronic devices104are arranged so that electronic devices104from other sets are adjacent each side of the electronic device104. For example, each electronic device104of set108is adjacent an electronic device104of set106on a left side, and adjacent an electronic device104of set110on a right side (referring toFIG. 1).

The cooling assembly100also includes a heat sink (not shown) disposed on the second surface of the circuit board102. The heat sink is in thermal contact with the first set106of electronic devices104, the second set108of electronic devices104, and the third set110of electronic devices104to facilitate dissipation of heat from the electronic devices104.

As shown inFIG. 1, the electronic devices104are disposed on the surface103of the circuit board102in a substantially linear arrangement. The two electronic devices104at opposite ends of the linear arrangement are adjacent only a single other electronic device104.

The four electronic devices104in the middle portion of the linear arrangement are each disposed adjacent other electronic devices104belonging to different sets. For example, each of the four electronic devices104in the middle portion have electronic devices104belonging to different sets disposed adjacent opposite sides of the electronic device104.

Therefore, none of the electronic devices104inFIG. 1are adjacent another electronic device104belonging to the same set (although in some embodiments at least two electronic devices belonging to the same set may be adjacent one another, etc.).

The arrangement of the electronic devices104inFIG. 1may be considered as an interleaved arrangement, etc. This arrangement can reduce concentrations of current flows, because electronic devices104belonging to the same set which are coupled in parallel are located at spaced positions on the circuit board102. Therefore, the electromagnetic fields generated by current flow through electronic devices104belonging to the same set can be reduced.

As mentioned above, the specific arrangement of electronic devices104illustrated inFIG. 1is only one example embodiment of the cooling assembly100. In other embodiments, the cooling assembly100may include more or less than three sets of electronic devices104, may include more than two electronic devices104per set (e.g., three per set, etc.), etc. The electronic devices104may be arranged in other than a linear arrangement, the electronic devices104may be arranged so that one or more of the electronic devices104are adjacent other electronic device(s)104belonging to a same group, etc.

FIG. 2illustrates a cooling assembly200for electronic devices, according to another example embodiment of the present disclosure. The cooling assembly200includes a circuit board202having a first surface203, and a second surface (not shown) opposite the first surface203.

The cooling assembly200includes a first set206of electronic devices204, a second set208of electronic devices204, and a third set210of electronic devices204. As shown inFIG. 2, each set includes three electronic devices204. Within each set, the electronic devices204are coupled in parallel with one another, via circuit traces212.

As one example, in each set the electronic devices204may include multiple field-effect transistors (FETs) that are used for current sharing. In this case, a desired number of FETs may be selected based on a current flowing through the FETs (e.g., an output current of a power supply including the FETs, etc.). Higher output currents may increase the number of FETs per set, while lower output currents may decrease the number of FETs per set.

One example circuit arrangement for coupling the electronic devices204(e.g., FETs) in each set206,208and210is illustrated inFIG. 3, and referenced generally by301. The circuit arrangement301is disposed on a secondary side of a power converter (not shown).

As shown inFIG. 3, the first set206includes three forward FETs (FET1, FET2and FET3) coupled in parallel. The first set206is coupled to a secondary winding S1of a first forward transformer T1. Therefore, the three forward FETs of the first set206can transfer energy received at the secondary winding S1of the first forward transformer T1(e.g., by current sharing among the FETs) when the power converter is operating in a forward mode.

Similarly, the third set210includes three forward FETs (FET4, FET5and FETE) coupled in parallel. The third set210is coupled to a secondary winding S1a second forward transformer T2. Therefore, the three forward FETs of the third set210can transfer energy received at the secondary winding S1of the second forward transformer T2when the power converter is operating in the forward mode.

The second set208includes three flywheel metal-oxide-semiconductor FETs (MOSFET1, MOSFET2and MOSFET3) coupled in parallel. The second set208is coupled to a forward output choke L1. Therefore, the three flywheel MOSFETs of the second set208can provide a discharge loop for an output choke current when the forward FETs of the first set206and/or the forward FETs of the third set210are OFF. In this case, the flywheel MOSFETs of the second set208are ON. During the forward mode, the flywheel MOSFETs of the second set208are OFF and the forward FETs of the first set206and/or the forward FETs of the third set210are ON.

The circuit arrangement301illustrated inFIG. 3is only one example embodiment, and the electronic devices204of the first set206, the second set208and the third set210may be coupled in other circuit arrangements in other embodiments.

Referring back toFIG. 2, some of the electronic devices204are arranged so that electronic devices204from other sets are adjacent each side of the electronic device204. For example, each electronic device204of set208is adjacent an electronic device204of set206on a left side, and adjacent an electronic device204of set210on a right side.

The cooling assembly200also includes a heat sink214disposed on the second surface of the circuit board202. The heat sink214is in thermal contact with the first set206of electronic devices204, the second set208of electronic devices204, and the third set210of electronic devices204to facilitate dissipation of heat from the electronic devices204.

FIG. 4is a sectional view of the cooling assembly200, illustrating a thermal heat path from one of the electronic devices204to the heat sink214. As shown inFIG. 4, the printed circuit board202includes multiple vias216(e.g., plated via holes, etc.) between the first surface203and the second surface205of the circuit board202.

The vias216facilitate thermal contact (e.g., heat transfer, dissipation, etc.) between the electronic device204on the first surface203of the circuit board202, and the heat sink214on the second surface205of the circuit board. For example, the electronic device204may include a surface mount device, such that the vias216are in thermal contact with a surface of the electronic device204.

AlthoughFIG. 4illustrates four vias216, other embodiments may include more or less vias216, vias216spaced in different arrangements between the first surface203and the second surface205of the circuit board202, vias216spaced in different arrangements relative to the electronic device204and the heat sink214, etc.

As shown inFIG. 4, the heat sink214includes a fin structure218. The fin structure218includes multiple fins adapted to facilitate heat dissipation from the heat sink214and the electronic devices204. Further details of the heat sink214and fin structure218will be described below.

As described above, the electronic devices herein may include any suitable electronic components (e.g., power devices, etc.) that generate undesired heat during operation. For example, in some embodiments the electronic components may include switching devices. Specifically, the electronic components may include metal-oxide-semiconductor field-effect transistors (MOSFETs).

FIG. 5illustrates an example MOSFET electronic device204. The MOSFET includes a drain220and four source terminals222(although other embodiments may include more or less drain and source terminals, etc.). As shown inFIG. 5, the drain220and source terminals222are surface mount terminals of the MOSFET.

Referring back toFIG. 4, in cooling assembly200the drain220of electronic device204(e.g., a MOSFET, etc.) is in thermal contact with the vias216, to facilitate heat transfer from the drain220of the electronic device204to the heat sink214.

FIG. 6illustrates the heat sink214disposed on the second surface205of the circuit board202. As shown inFIG. 6, the heat sink214includes a first heat sink portion226, a second heat sink portion228, and a third heat sink portion230.

Each heat sink portion is in thermal contact with a corresponding one of the sets of electronic devices204. The first heat sink portion226is in thermal contact with the electronic devices204of the first set206, the second heat sink portion228is in thermal contact with the electronic devices204of the second set208, and the third heat sink portion230is in thermal contact with the electronic devices204of the third set210.

The three heat sink portions inFIG. 6are electrically isolated from one another (e.g., there is no physical contact between the three heat sink portions, etc.). Therefore, the three heat sink portions may keep the three sets of electronic devices204electrically isolated from one another in the cooling assembly200.

For example, if the electronic devices204of each set are electrically isolated from electronic devices204of other sets on the first surface203of the circuit board, the three heat sink portions may maintain electrical isolation between the different sets of electronic devices204(i.e., the heat sink portions will not short an electrical connection between electronic devices204belonging to different sets, etc.). In some embodiments, one or more of the electronic devices204may be non-insulated devices. Therefore, the three separate portions of the heat sink214can inhibit electrical coupling through the heat sink214of electronic devices204belonging to different sets.

As shown inFIG. 6, each heat sink portion includes three board contact surfaces224. Each board contact surface224corresponds to one of the electronic devices204on the first surface203of the circuit board202, to provide thermal contact with the electronic device204when the board contact surface224is disposed on the second surface205of the circuit board202opposite the electronic device204.

The three heat sink portions each include a substantially horizontal cross bar232from which the board contact surfaces224extend. The three horizontal cross bars232are arranged in substantially separate parallel planes to inhibit the cross bars232from contacting one another. Similarly, the board contact surfaces224extend in directions that avoid contacting one another, to maintain electrical isolation between the three heat sink portions. The board contact surfaces224are arranged in a substantially similar pattern (e.g., interleaved, etc.) as the sets of electronic devices204to which they correspond.

FIG. 7illustrates a heat sink414according to another example embodiment of the present disclosure. As shown inFIG. 7, the heat sink414includes a fin structure418, an electrical insulation layer434, a first heat sink portion426, a second heat sink portion428, and a third heat sink portion430.

The electrical insulation layer434is disposed between the fin structure418and the three heat sink portions426,428and430. The electrical insulation layer434provides thermal contact between the fin structure418and the three heat sink portions426,428and430, so the fin structure418can dissipate heat from the three heat sink portions426,428and430(and electronic components/circuit board(s) coupled to the three heat sink portions, etc.).

The electrical insulation layer434may comprise any suitable material capable of transferring heat from the three heat sink portions to the fin structure418, while maintaining electrical isolation between the fin structure418and the three heat sink portions. For example, the electrical insulation layer434may have a high thermal conductivity value, a high dielectric characteristic, etc.

Therefore, the electrical insulation layer434allows the heat sink portions to remain electrically isolated from one another while dissipating heat through the fin structure418. The electrical insulation layer434may include adhesive to bond the fin structure418to the three heat sink portions426,428and430.

FIGS. 8A and 8Billustrate side and front views, respectively, of the heat sink414illustrated inFIG. 7. As shown inFIG. 8A, the fin structure418includes multiple fins for dissipating heat from the heat sink414. The electrical insulation layer434is coupled between the fin structure and the heat sink portions428and430(heat sink portion426not visible).

As illustrated inFIG. 8B, the heat sink portions426,428and430each include board contact surfaces424which are spaced from one another (e.g., in an interleaved arrangement, etc.). This allows the heat sink portions426,428and430to remain electrically isolated from one another, thereby maintaining electrical isolation between sets of electronic devices to which the heat sink portions are coupled.

The heat sink414also includes two protrusions436(e.g., extrusions, etc.), located at opposite ends of the heat sink414. The protrusions436are adapted to be received in guides on a surface of a circuit board opposite electronic devices, to position the board contact surfaces424in thermal contact with corresponding devices. For example, the protrusions436may define semi-spheres, while the circuit board surface includes corresponding semi-sphere cavities to receive the protrusions436.

FIG. 9illustrates a cooling assembly500for electronic devices504according to another example embodiment of the present disclosure. As shown inFIG. 9, a first set506of electronic devices504, a second set508of electronic devices504, and a third set510of electronic devices504are disposed on a circuit board502.

A heat sink514is adapted to couple to a surface of the board502opposite the electronic devices504. For example, the heat sink514may be soldered, etc. to the circuit board502. The heat sink514includes three heat sink portions526,528and530, each corresponding to a different one of the sets506,508and510. The heat sink514includes an electrical insulation layer534coupled between a fin structure518and the three heat sink portions526,528and530.

The heat sink514also includes protrusions536, which are received in guides (e.g., cavities, etc.; not shown) of the circuit board502. The protrusions536align board contact surfaces524of the heat sink portions526,528and530with the corresponding electronic devices504of the sets506,508and510.

Any of the example embodiments and aspects disclosed herein may be used in any suitable combination with any other example embodiments and aspects disclosed herein without departing from the scope of the present disclosure. For example, electronic device arrangements described herein may be used with other heat sinks, the heat sinks may be used with other electronic device arrangements, etc. without departing from the scope of the present disclosure.

Example embodiments and aspects of the present disclosure may provide any one or more (or none) of the following advantages: simplified solder reflow process (e.g., no fixture is needed to secure several heat sink portions on the circuit board, etc.), increased efficiency of assembly if only one heat sink is required, enhanced cooling performance via an increased size of heat transfer surfaces, etc.