Patent ID: 12200900

DESCRIPTION OF THE EMBODIMENTS

FIG.1is a schematic cross-sectional view of an electronic device according to an embodiment of the disclosure. With reference toFIG.1, an electronic device100of this embodiment includes a circuit board110, a package on package structure (POP structure)120, a heat-conducting cover130, and a heat-conducting fluid140. The circuit board110has a first surface112and a second surface114opposite to each other. The package on package structure120is disposed on the first surface112. The package on package structure120has at least one heat generating element122. The heat-conducting cover130is disposed on the second surface114and is in thermal contact with the circuit board110. The heat-conducting cover130and the second surface114form an enclosed space S10. The heat-conducting fluid140is filled in the enclosed space S10.

In the electronic device100of this embodiment, the circuit board110, the heat-conducting cover130, and the heat-conducting fluid140form a heat dissipation means similar to a vapor chamber formed by two heat-conducting plates and a heat-conducting fluid therein. Compared with the additionally disposed the vapor chamber, the electronic device100of this embodiment has a less overall thickness. Besides, the combination of the heat-conducting cover130and the heat-conducting fluid140also exhibits a good heat dissipation effect.

In this embodiment, the heat generating element122is a central processing unit, but may also be an image processing chip or other high-power chips. Besides, the package on package structure120may further have a chip124disposed on the heat generating element122. In this embodiment, the chip124may be a memory chip or other types of chips. In this embodiment, the chips124may include one chip or a plurality of chips, and the plurality of chips124may be arranged side by side or stacked on the heat generating element122. The electronic device100of this embodiment may further include a plurality of electronic components150disposed on the second surface114and located in the enclosed space S10. In this embodiment, the electronic components150may be chips or passive elements, and the passive elements may be resistors, capacitors, or inductors. In other words, the conventional heat sink or vapor chamber may be affected by the electronic components150and thus cannot be used. However, the heat-conducting fluid140is filled between the electronic components150. Therefore, the size of the area available for the electronic components150to be disposed on the second surface114of the circuit board110is not greatly affected by the disposed heat-conducting cover130. The heat-conducting fluid140filled between the electronic components150may still quickly dissipate heat to prevent damage caused by a local high temperature. In this embodiment, the heat-conducting fluid140has a high thermal conductivity coefficient and an electrical insulation property. The heat-conducting fluid140is not limited to water, and may also be other fluids having a high thermal conductivity coefficient, as long as it is likely to be reliably filled in the enclosed space S10. For example, a thermal paste or a phase change material may also serve as the heat-conducting fluid140.

To be more specific, since the chip124is disposed on the heat generating element122, heat generated by the heat generating element122is not easily transferred to the external environment through the chip124. In this embodiment, since the heat-conducting cover130is disposed below the heat generating element122and filled with the heat-conducting fluid140, the heat generated by the heat generating element122is relatively easily transferred to the heat-conducting cover130and the heat-conducting fluid140through the internal circuits of the circuit board110. Besides, the electronic components150also facilitate heat dissipation and increase the contact area with the heat-conducting fluid140. When the heat generating element122instantly increases power or calculation speed, the heat generating element122instantly generates more heat energy, that is, thermal impact. The heat-conducting fluid140and the heat-conducting cover130of this embodiment quickly absorb heat energy to reduce the influence by thermal impact. In other words, when the heat generating element122instantly increases power or calculation speed, the local temperature does not rise overly high, and the influence on the service life of the package on package structure120is reduced.

In this embodiment, an inner surface132of the heat-conducting cover130located in the enclosed space S10and opposite to the second surface114is non-planar. When heights of the electronic components150are inconsistent, it may be configured that a distance is kept between the inner surface132and the electronic components150. Therefore, a thermal resistance between the heat-conducting cover130and the electronic components150can be reduced, helping to increase the heat dissipation efficiency. To be more specific, the distance between the heat-conducting cover130and the electronic components150may affect the thermal resistance. As the distance decreases, the thermal resistance decreases, and the heat dissipation efficiency increases. However, too close a distance may increase the probability of a short circuit generated by contact between the electronic components and the heat-conducting cover130. Therefore, the distance between the inner surface132and the electronic components150is preferred to be shortest possible without causing a short circuit.

In this embodiment, the heat-conducting cover130has an inlet134and an outlet136. The inlet134is used for the heat-conducting fluid140to be filled in the enclosed space S10, and the outlet136is used for air and excess of the heat-conducting fluid140to flow out. During assembly, for example, the heat-conducting cover130is first bonded to the second surface114of the circuit board110, and then, the heat-conducting fluid140is filled from the inlet134into the enclosed space S10. During this process, air in the enclosed space S10may be discharged from the outlet136. When the heat-conducting fluid140also flows out of the outlet136, it can be determined that the enclosed space S10should have been fully filled with the heat-conducting fluid140. At this time, the inlet134and the outlet136may be closed to enclose the heat-conducting fluid140in the enclosed space S10. In another embodiment, it is also possible that a large amount of heat-conducting fluid140with poor fluidity is first disposed on the second surface114, and then the heat-conducting fluid140is directly covered with the heat-conducting cover130, which in the meantime is bonded to the circuit board110, thus enclosing the heat-conducting fluid140in the enclosed space S10.

In this embodiment, the circuit board110has a grounding pattern116exposed from the second surface114. The heat-conducting cover130is in thermal contact with the grounding pattern116. The material of the grounding pattern116of this embodiment includes copper, for example. Since it is originally intended the package on package structure120is connected to the grounding circuit in the circuit board110, the heat generated by the package on package structure120may also be transferred to the heat-conducting cover130through grounding circuits and the grounding pattern116, thereby increasing the heat dissipation efficiency. Besides, multiple grounding layers may also be disposed in the circuit board110to increase the heat dissipation efficiency.

In this embodiment, the electronic device100further includes a heat-conducting soft pad160disposed between the heat-conducting cover130and the second surface114, such that the heat-conducting cover130is in thermal contact with the circuit board110. When the heat-conducting cover130cannot be closely fitted with the second surface114due to poor flatness, the heat-conducting soft pad160can prevents generation of a relatively great thermal resistance due to existence of gaps between the heat-conducting cover130and the second surface114. Similarly, the heat-conducting soft pad160may also be disposed between the grounding pattern116exposed by the circuit board110and the heat-conducting cover130to increase the heat dissipation efficiency.

In this embodiment, the orthogonal projection of the package on package structure120on the second surface114is completely covered by the orthogonal projection of the heat-conducting cover130on the second surface114. That is, when being viewed from a direction perpendicular to the second surface114, the package on package structure120is completely located within the range of the heat-conducting cover130. Since the shortest heat transfer path may be obtained from such an arrangement, the heat dissipation efficiency will also be better. However, in other embodiments where there are other design considerations, it is also possible that the orthogonal projection of the package on package structure120on the second surface114is only partially overlapped with the orthogonal projection of the heat-conducting cover130on the second surface114, but the application is not limited thereto.

Besides, the electronic device100of this embodiment may include a heat pipe170, a heat dissipation fin172, and a fan174, but the application is not limited thereto. The heat pipe170is in thermal contact with the heat-conducting cover130. The heat dissipation fin172is in thermal contact with the heat pipe170. The fan174dissipates heat from the heat dissipation fin172. In other words, in this embodiment, various combinations of the heat pipe170, the heat dissipation fin172, and the fan174may also be adopted and may be in thermal contact with the heat-conducting cover130to increase the heat dissipation efficiency.

FIG.2is a schematic cross-sectional view of an electronic device according to another embodiment of the disclosure. With reference toFIG.2, an electronic device200of this embodiment is generally the same as the electronic device100ofFIG.1. The difference lies in that the electronic device200further includes a heat dissipation pad176and a bracket180. The package on package structure120is in thermal contact with the bracket180through the heat dissipation pad176. Similarly, in this embodiment, various combinations of the heat pipe170, the heat dissipation fin172, and the fan174may also be adopted and may be in thermal contact with the heat-conducting cover130to increase the heat dissipation efficiency. The bracket180may be an element serving as the main support structure in the electronic device200, or it may as well be the housing or other elements with good thermal conductivity of the electronic device200.

FIG.3is a schematic cross-sectional view of an electronic device according to still another embodiment of the disclosure. With reference toFIG.3, an electronic device300of this embodiment is generally the same as the electronic device100ofFIG.1. The difference lies in that the electronic device300further includes a heat dissipation pad176, a heat dissipation device178, another heat pipe170, and another heat dissipation fin172. The heat dissipation device178is in thermal contact with the package on package structure120through the heat dissipation pad176. The another heat pipe170is in thermal contact with the heat dissipation device178. The another heat dissipation fin172is in thermal contact with the another heat pipe170. The fan174dissipates heat from the two heat dissipation fin172. Similarly, in this embodiment, various combinations of the heat pipe170, the heat dissipation fin172, the fan174, the heat dissipation pad176, and the heat dissipation device178may also be adopted and may be in thermal contact with the heat-conducting cover130to increase the heat dissipation efficiency.

In summary of the foregoing, in the electronic device of this application, a heat dissipation means formed by the heat-conducting cover and the heat-conducting fluid is disposed on the back of the circuit board, in which heat dissipation may be performed on the heat generating element122from the other side of the package on package structure, effectively improving the heat dissipation efficiency of the package on package structure.