Packaging structure based on diamond heat dissipation

Abstract

The utility model discloses a packaging structure based on diamond heat dissipation, which comprises a heat dissipation layer, and the heat dissipation layer wraps a chip and a bonding wire and is made of diamond powder. The heat dissipation material is made of diamond powder and wraps the chip to form the heat dissipation layer, and the heat conductivity of diamond is far higher than that of metal such as copper, so that the heat dissipation performance of the chip can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, and in particular to a packaging structure based on diamond heat dissipation. Background Art

[0002] As the power and circuit density of active and passive semiconductor integrated circuit (IC) devices increase, the heat generated by IC devices during operation is also increasing. If the thermal management is not adequate, it is very likely to affect the performance of the IC device, and even cause permanent structural damage. At present, the common heat dissipation methods of chips mainly include radiation heat dissipation, conduction heat dissipation, convection heat dissipation, evaporation heat dissipation, etc. Among them, conduction heat dissipation is the most important heat dissipation method for chips. Packaging is the main carrier of chip conduction heat dissipation, and the packaging heat dissipation path method also directly affects the heat dissipation effect of the chip.

[0003] Figure 1 Figure 2 shows a common chip packaging method. Figure 1 As shown in FIG. 1 , the back of the chip 001 is fixed on a large piece of metal material at the bottom of the package 002, and the pad (PAD) on the chip is connected to the package pin 004 through the bonding wire 003. The package shell 005 bonds the entire package pin 004 and the package bottom 002 together. The packaged chip is connected to the printed circuit board 006 (PCB) by solder, and the heat loss of the chip is transferred to the upper surface of the PCB, and then conducted to the bottom of the PCB through the metal via 007 on the PCB for heat dissipation. A large piece of metal is usually set at the bottom of the PCB to improve the heat dissipation effect. The above heat dissipation method depends on the number of metal vias on the PCB and the size of the metal area at the bottom of the PCB. If the number of metal vias is small or the metal heat dissipation area is insufficient, the heat generated by the chip cannot be dissipated, and an additional air cooling or water cooling system is often required for auxiliary heat dissipation, which increases the cost and makes the device structure more complicated. Utility Model Content

[0004] In view of some or all of the problems in the prior art, the utility model provides a packaging structure based on diamond heat dissipation, including:

[0005] The heat dissipation layer covers the chip and the bonding wires, and the heat dissipation layer is made of diamond powder.

[0006] Furthermore, the particle diameter of the diamond powder is between 5 microns and 50 microns.

[0007] Furthermore, the heat dissipation layer also includes an adhesive.

[0008] Furthermore, the adhesive includes epoxy resin glue.

[0009] Furthermore, the content of diamond powder in the heat dissipation layer is not less than 60%.

[0010] Furthermore, the content of diamond powder in the heat dissipation layer is 80%.

[0011] Furthermore, the packaging structure further includes:

[0012] The substrate is provided with a metal layer, the metal layer includes an external pad, the chip is mounted on the surface of the metal layer and connected to the external pad through a bonding wire.

[0013] Furthermore, the packaging structure further includes:

[0014] The substrate is a metal frame structure and includes an external pad. The chip is mounted on the surface of the substrate and connected to the external pad through a bonding wire.

[0015] Furthermore, the packaging structure further includes:

[0016] The plastic packaging material covers the substrate and the heat dissipation layer.

[0017] Furthermore, the heat dissipation layer also includes a resin material, and the heat dissipation layer also covers the substrate.

[0018] The utility model provides a packaging structure based on diamond heat dissipation, which adopts diamond powder to make heat dissipation material and covers the chip to form a heat dissipation layer. Since the thermal conductivity of diamond is much higher than that of metals such as copper, the heat dissipation performance of the chip can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding components will be represented by identical or similar reference numerals.

[0020] Figure 1 A schematic diagram showing the structure of a chip package in the prior art is shown;

[0021] Figure 2 A schematic structural diagram showing a packaging structure based on diamond heat dissipation according to an embodiment of the utility model; and

[0022] Figure 3 A schematic flow chart of a method for manufacturing a packaging structure based on diamond heat dissipation according to an embodiment of the utility model is shown. DETAILED DESCRIPTION

[0023] In the following description, the utility model is described with reference to various embodiments. However, those skilled in the art will recognize that the various embodiments can be implemented without one or more specific details or with other replacement and / or additional methods, materials or components. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid blurring the utility model points of the utility model. Similarly, for the purpose of explanation, specific quantities, materials and configurations are set forth to provide a comprehensive understanding of the embodiments of the utility model. However, the utility model is not limited to these specific details. In addition, it should be understood that the various embodiments shown in the drawings are illustrative representations and are not necessarily drawn in correct proportions.

[0024] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present utility model. The phrase "in one embodiment" appearing in various places in this specification does not necessarily refer to the same embodiment.

[0025] It should be noted that the embodiments of the present invention describe the process steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to the adjustment of the process.

[0026] This case is based on the following insight of the utility model inventor: in the existing packaging structure, especially in the chip front mounting process, the heat of the chip is mainly conducted to the metal substrate through the bonding wire, thereby achieving heat dissipation. The bonding wire is usually made of metals such as copper, and the thermal conductivity of copper is about 370W / (m·K), so the thermal conductivity efficiency is not high. For some high-power chips, it is necessary to use additional heat dissipation modules to achieve heat dissipation. The provision of additional heat dissipation modules may make the manufacturing process more complicated, and at the same time increase the overall volume of the package, which is not conducive to the development of miniaturization of the packaging structure. Diamond is a material with extremely high thermal conductivity, and its thermal conductivity is as high as 4000W / (m·K). Therefore, it can be considered to use diamond as a heat dissipation material, such as adding a layer of diamond between the metal substrate and the chip, and opening a hole in the diamond to expose the external pads on the metal substrate, etc., so as to facilitate electrical connection with the chip. However, the price of single-crystal diamond is relatively high. For cost considerations, it is not suitable for use in packaging structures. Although polycrystalline synthetic diamond is relatively low in cost, it usually needs to be formed by methods such as chemical vapor deposition, which increases the steps and difficulty of the packaging process. In addition, due to the large difference in expansion coefficient between diamond itself and other materials in the packaging structure, this method increases the thickness of the packaging structure on the one hand, and increases the risk of warping on the other hand. Based on this, the utility model inventor further discovered that, compared with the formed diamond structure, although the thermal conductivity of diamond powder is reduced, it is still much higher than materials such as copper metal. Diamond powder is low-cost and easy to obtain. By doping it with a certain amount of adhesive, it can be made into a colloid state, and then it can be directly applied to the surface of the chip to form a heat dissipation structure. The heat dissipation structure obtained in this way is simple in process, high in heat dissipation efficiency, and has little effect on the size of the packaging structure.

[0027] The scheme of the utility model is further described below in conjunction with the accompanying drawings of the embodiments.

[0028] Figure 2 The schematic diagram of a packaging structure based on diamond heat dissipation in one embodiment of the utility model is shown. Figure 2As shown, a packaging structure based on diamond heat dissipation includes a substrate 201, a chip 202 and a heat dissipation layer 203. The substrate 201 may be a PCB substrate or a metal frame structure or other common structures and forms in the art, and an external pad is provided on the substrate 201. The chip 202 is provided on the surface of the substrate 201 by front mounting, and is electrically connected to the external pad provided on the substrate through a bonding wire 204. In one embodiment of the utility model, the bonding wire may be a gold wire, an aluminum wire, a copper wire, etc. The heat dissipation layer 203 covers the chip 202 and the bonding wire 204, and the heat dissipation layer 203 is made of diamond powder. In one embodiment of the utility model, the particle diameter of the diamond powder is between 5 microns and 50 microns, for example, 5 microns or 10 microns or a mixture of 5-50 microns can be selected. It should be understood that in some embodiments of the present invention, the chip 202 may also be directly mounted on the substrate 201 by back mounting, and at this time, the heat dissipation layer 203 covers the chip 202 to achieve heat dissipation.

[0029] In one embodiment of the present invention, the heat dissipation layer 203 only covers the chip 202 and the bonding wire 204, and its thickness is higher than the bonding wire 204. The main component of the heat dissipation layer 203 is diamond powder. In one embodiment of the present invention, the content of diamond powder in the heat dissipation layer is not less than 60%. Preferably, the content of diamond powder in the heat dissipation layer is 80%. In order to make the diamond powder bond together to form a glue or solid state, in one embodiment of the present invention, the heat dissipation layer also includes an adhesive, and the adhesive can be, for example, epoxy resin glue. In the actual operation process, a certain amount of diluent can also be added therein to facilitate the coating of the heat dissipation layer on the surface of the chip. The diluent is volatile, so it can evaporate in the subsequent process steps to solidify the heat dissipation layer. In one embodiment of the present invention, the packaging structure further includes a plastic sealing layer 205, which seals the overall structure of the substrate 201, the chip 202 and the heat dissipation layer 203 to protect the chip, provide good mechanical strength and electrical performance for the chip, and prevent oxidation and contamination of the chip surface. In one embodiment of the present invention, the plastic sealing layer can be made of materials such as epoxy resin, curing glue, EMC, etc.

[0030] In another embodiment of the utility model, a material made of diamond powder is directly used as a plastic sealing layer, specifically, a specified proportion of diamond powder is added to a resin material, wherein the content of the diamond powder is 50% to 90%. The plastic sealing layer can protect the chip, provide good mechanical strength and electrical performance for the chip, and prevent oxidation and contamination of the chip surface. On the other hand, since it is doped with diamond powder, it can also play a role in heat conduction and heat dissipation.

[0031] In some other embodiments of the present invention, vertical connection of the chip can be further achieved through silicon vias, metal pillars, etc., and / or fan-out packaging can be achieved through a rewiring structure.

[0032] Figure 3 The following is a flow chart showing a method for manufacturing a packaging structure based on diamond heat dissipation according to an embodiment of the present invention. Figure 3 As shown, the manufacturing method of the packaging structure as mentioned above includes:

[0033] First, in step 301, a heat dissipation material is prepared. A preset ratio of adhesive, diluent and diamond powder are mixed to form a heat dissipation material. The ratio of the diamond powder is not less than 60%, preferably 80%, and the obtained heat dissipation material is in a gel or fluid state;

[0034] Next, in step 302, the chip is mounted. The chip is mounted on the surface of the substrate by front mounting, so that the pads of the chip face upward, and then the pads of the chip are connected to the external pads of the metal layer on the substrate by bonding wires;

[0035] Next, in step 303, a heat dissipation layer is formed. The heat dissipation material prepared in step 301 is coated on the chip and the bonding wire to cover the chip, the bonding wire and the metal pins of the substrate to form a heat dissipation layer. Since the diluent is volatile, the heat dissipation material will gradually solidify after coating; and

[0036] Finally, in step 304, a plastic encapsulation layer is formed. The entire structure consisting of the substrate, the chip, the bonding wires and the heat dissipation layer is encapsulated with a plastic encapsulation material, and then cut into individual package structures.

[0037] As mentioned above, the material made of diamond powder can also be directly used as the plastic sealing layer. In this way, the manufacturing steps of the packaging structure are slightly different from the above steps, including:

[0038] First, make the plastic packaging material. Mix the preset proportion of adhesive, diluent, resin material and diamond powder to form a heat dissipation material. The proportion of the diamond powder is not less than 50%;

[0039] Next, mount the chip. Mount the chip on the surface of the substrate by front mounting so that the pads of the chip face upwards, and then connect the pads of the chip to the external pads of the metal layer on the substrate by bonding wires;

[0040] Next, a plastic encapsulation layer is formed. The plastic encapsulation material prepared in the above steps is used to encapsulate the entire structure consisting of the substrate, the chip, and the bonding wires, and then cut to form a single package structure.

[0041] In some other embodiments of the present invention, flip-chip bonding can also be used to directly connect the chip pad to the substrate. There are no bonding wires in the flip-chip structure, so the method of forming the heat dissipation layer and the plastic sealing layer of the flip-chip is basically the same as that of the upright chip, and only the bonding wires can be ignored.

[0042] It should be understood that in the embodiments of the present invention, vertical connection of the chip can be further achieved through silicon vias, metal pillars, etc., and / or fan-out packaging can be achieved through a rewiring structure, etc., which can be achieved using common processes in the field and will not be described in detail here.

[0043] The utility model provides a packaging structure based on diamond heat dissipation and a manufacturing method thereof. Diamond powder is used to make a heat dissipation material, and a chip is coated to form a heat dissipation layer. Since the thermal conductivity of diamond is much higher than that of metals such as copper, the heat dissipation performance of the chip can be effectively improved.

[0044] Although various embodiments of the utility model are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the utility model. Therefore, the breadth and scope of the utility model disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A packaging structure based on diamond heat dissipation, characterized in that: include: The heat dissipation layer covers the chip and the bonding wires, and the heat dissipation layer is made of diamond powder.

2. The packaging structure according to claim 1, characterized in that: The particle diameter of the diamond powder is between 5 microns and 50 microns.

3. The packaging structure according to claim 1, characterized in that: The heat dissipation layer also includes an adhesive.

4. The packaging structure according to claim 3, characterized in that: The adhesive includes epoxy resin glue.

5. The packaging structure according to claim 1, characterized in that: Also includes: The substrate is provided with a metal layer, the metal layer includes an external pad, the chip is mounted on the surface of the metal layer and connected to the external pad through a bonding wire.

6. The packaging structure according to claim 1, characterized in that: Also includes: The substrate is a metal frame structure and includes an external pad. The chip is mounted on the surface of the substrate and connected to the external pad through a bonding wire.

7. The packaging structure according to claim 5 or 6, characterized in that: Also includes: The plastic packaging material covers the substrate and the heat dissipation layer.

8. The packaging structure according to claim 5 or 6, characterized in that: The heat dissipation layer further comprises a resin material, and the heat dissipation layer further covers the substrate.

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