FCCSP structure and chip packaging method

Abstract

The invention discloses an FCCSP structure and a chip packaging method. The FCCSP structure comprises: a packaging substrate; the bottom of the chip is fixed on the surface of the packaging substrate; the heat dissipation cover is in thermal contact with the top of the chip; the heat dissipation cover is at least partially embedded in the plastic package structure; the plastic package structure is used for fixing the heat dissipation cover; the plastic package structure at least exposes the outer surface of a thermal contact part of the heat dissipation cover and the top of the chip.

Description

Technical Field

[0001] The present application relates to the technical field of chip packaging, and more specifically, to a FCCSP (Flip-Chip Chip Scale Package) structure and a chip packaging structure. Background Art

[0002] With the continuous development of science and technology, more and more electronic devices are widely used in people's daily life and work, bringing great convenience to people's daily life and work and becoming an indispensable important tool for people today.

[0003] A chip is the core component for an electronic device to achieve various functions. The chip needs to be packaged and protected to facilitate the connection between the chip and an external circuit and prevent damage to the chip caused by external forces.

[0004] Currently, for the chip packaging technology, epoxy molding compound is mostly used to directly encapsulate and protect the chip fixed on a circuit board, seriously affecting the heat dissipation performance of the chip. Summary of the Invention

[0005] In view of this, the present application provides a FCCSP structure and a chip packaging structure, and the solutions are as follows:

[0006] A FCCSP structure includes:

[0007] A packaging substrate;

[0008] A chip, the bottom of the chip is fixed on the surface of the packaging substrate;

[0009] A heat dissipation cover, the heat dissipation cover is in thermal contact with the top of the chip;

[0010] A plastic encapsulation structure, at least part of the heat dissipation cover is embedded in the plastic encapsulation structure; the plastic encapsulation structure is used to fix the heat dissipation cover; the plastic encapsulation structure at least exposes the outer surface of the part where the heat dissipation cover is in thermal contact with the top of the chip.

[0011] Preferably, in the above FCCSP structure, a thermal conductive adhesive is filled between the heat dissipation cover and the chip, and the thermal conductivity of the thermal conductive adhesive is greater than 6.7 W / (m·K).

[0012] Preferably, in the above FCCSP structure, the heat dissipation cover is a flat plate structure, and the flat plate structure is flush with the edge of the chip.

[0013] Preferably, in the above FCCSP structure, the heat dissipation cover includes a heat conductive top and a heat conductive side wall surrounding the heat conductive top, the heat conductive top and the heat conductive side wall form a receiving cavity; at least part of the chip is located in the receiving cavity; the part of the chip located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity.

[0014] Preferably, in the above FCCSP structure, the heat dissipation cover comprises: a heat-conductive top and a heat-conductive bottom surrounding the heat-conductive top, a heat-conductive side wall is provided between the heat-conductive bottom and the heat-conductive top, the heat-conductive top and the heat-conductive side wall form a receiving cavity, at least part of the chip is located in the receiving cavity; the part of the chip located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity;

[0015] The heat-conducting bottom is embedded in the plastic packaging structure, the heat-conducting bottom extends in a direction away from the side wall of the chip, and the heat-conducting bottom is fixed to the packaging substrate through the plastic packaging structure.

[0016] Preferably, in the above FCCSP structure, the plastic encapsulation structure is a single plastic encapsulation adhesive layer;

[0017] Or, the plastic packaging structure at least includes:

[0018] A first plastic sealing adhesive layer, the first plastic sealing adhesive layer and the chip are located on the same side surface of the packaging substrate, filling the gap between the heat conductive bottom and the packaging substrate, and filling the gap between the bottom of the chip and the packaging substrate;

[0019] A second plastic sealing layer, the second plastic sealing layer covers the heat-conducting bottom and surrounds the heat-conducting side wall;

[0020] The thermal expansion coefficients of the first plastic sealing layer and the second plastic sealing layer are different.

[0021] Preferably, in the above FCCSP structure, the thermal expansion coefficient of the chip is a 1 , the thermal expansion coefficient of the package substrate is a 2 , the thermal expansion coefficient of the first plastic sealing layer is a 3 , the thermal expansion coefficient of the second plastic sealing layer is a 4 ;

[0022] Among them, a 1 <a 3 <a 2 , and a 3 -a 1 <a 2 -a 3 and / or, a 1 <a 4 <a 2 , and a 4 -a 1 >a 2 -a 4 .

[0023] Preferably, in the above FCCSP structure, on the side of the FCCSP structure away from the packaging substrate, the height of the heat dissipation cover relative to the packaging substrate is flush with the height of the plastic packaging structure relative to the packaging substrate, or the height of the heat dissipation cover relative to the packaging substrate is greater than the height of the plastic packaging structure relative to the packaging substrate.

[0024] The present application also provides a chip packaging method, including:

[0025] Providing a packaging substrate;

[0026] Fixing a chip on the surface of the packaging substrate;

[0027] Setting a heat dissipation cover in thermal contact with the top of the chip to form a plastic packaging structure;

[0028] Wherein, the heat dissipation cover is at least partially embedded in the plastic packaging structure; the plastic packaging structure is used to fix the heat dissipation cover; the plastic packaging structure at least exposes the outer surface of the part where the heat dissipation cover is in thermal contact with the top of the chip.

[0029] Preferably, in the above chip packaging method, the heat dissipation cover includes: a heat-conducting top and a heat-conducting bottom surrounding the heat-conducting top. There is a heat-conducting side wall between the heat-conducting bottom and the heat-conducting top. The heat-conducting top and the heat-conducting side wall form a receiving cavity; at least part of the chip is located in the receiving cavity; the part of the chip located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity;

[0030] The method of forming the plastic packaging structure includes:

[0031] After fixing the chip on the surface of the packaging substrate and before setting the heat dissipation cover, forming a first plastic encapsulation layer. The first plastic encapsulation layer is on the same side surface of the chip and the packaging substrate, fills the gap between the heat-conducting bottom and the packaging substrate, and fills the gap between the bottom of the chip and the packaging substrate;

[0032] After setting the heat dissipation cover covering the chip, forming a second plastic encapsulation layer. The second plastic encapsulation layer covers the heat-conducting bottom and surrounds the heat-conducting side wall;

[0033] Wherein, the thermal expansion coefficients of the first plastic encapsulation layer and the second plastic encapsulation layer are different.

[0034] From the above description, it can be seen that in the FCCSP structure and the chip packaging method provided by the technical solution of the present application, the FCCSP structure includes: a packaging substrate; a chip, the bottom of the chip is fixed on the surface of the packaging substrate; a heat dissipation cover, the heat dissipation cover is in thermal contact with the top of the chip; a plastic packaging structure, the heat dissipation cover is at least partially embedded in the plastic packaging structure; the plastic packaging structure is used to fix the heat dissipation cover; the plastic packaging structure at least exposes the outer surface of the part where the heat dissipation cover is in thermal contact with the top of the chip. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative efforts.

[0036] The structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the implementation conditions of this application. Therefore, they do not have any substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in this application.

[0037] Figure 1 It is a schematic diagram of an FCCSP structure;

[0038] Figure 2 It is a schematic diagram of another FCCSP structure;

[0039] Figure 3 It is a schematic diagram of yet another FCCSP structure;

[0040] Figure 4 It is a schematic diagram of an FCCSP structure provided by an embodiment of this application;

[0041] Figure 5 It is a schematic diagram of another FCCSP structure provided by an embodiment of this application;

[0042] Figure 6 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0043] Figure 7 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0044] Figure 8 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0045] Figure 9 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0046] Figure 10 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0047] Figure 11 It is a schematic diagram of yet another FCCSP structure provided by an embodiment of this application;

[0048] Figure 12 It is a process flow chart of a chip packaging method provided by an embodiment of this application;

[0049] Figures 13 - 17 It is a schematic diagram of the product structure in different process steps of a chip packaging method provided by an embodiment of this application;

[0050] Figures 18 - 19 This is a schematic diagram of the product structure in different process steps of another chip packaging method provided by the embodiments of the present application. Description of the drawings:

[0052] 11 - Packaging substrate; 12 - Chip; 13 - Plastic encapsulation structure; 14 - Heat sink cover; 15 - Thermal conductive adhesive; 121 - Chip pins; 111 - Solder balls; 141 - Thermal conductive top; 142 - Thermal conductive side wall; 143 - Thermal conductive bottom; 131 - First plastic encapsulation layer; 132 - Second plastic encapsulation layer. Detailed implementation manners

[0053] Next, the embodiments in the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0054] Referring to Figure 1 as shown, Figure 1 is a schematic diagram of an FCCSP structure, including:

[0055] Packaging substrate 11;

[0056] A chip 12 fixed on one side surface of the packaging substrate 11;

[0057] A plastic encapsulation structure 13 covering the chip 12.

[0058] Figure 1 In the FCCSP structure shown, directly using the plastic encapsulation structure 13 to cover the chip 12 seriously affects the heat dissipation performance of the chip 12, which limits the use of the FCCSP structure on chips with high thermal design power (TDP) and high power consumption.

[0059] Referring to Figure 2 as shown, Figure 2 is a schematic diagram of another FCCSP structure. Based on the manner shown in Figure 1 , in the FCCSP structure shown in Figure 2 , the plastic encapsulation structure 13 is set to surround the side wall of the chip 12, exposing the top of the chip 12 to improve the heat dissipation performance of the chip 12.

[0060] Compared with the manner shown in Figure 1 , although the manner shown in Figure 2 can improve the heat dissipation performance to a certain extent, the improvement of the heat dissipation performance is limited. In addition, since the top of the chip 12 needs to be exposed, it is easy to cause damage to the chip 12 due to external force acting on the top.

[0061] Reference Figure 3 as shown Figure 3 is a schematic diagram of another FCCSP structure. Based on the Figure 2 way shown Figure 3 in the FCCSP structure shown, a heat dissipation cover 14 is provided on the top of the chip 12, and the heat dissipation cover 14 is adhesively fixed to the top of the chip 12 and the top of the plastic package structure 13 through a thermal conductive adhesive 15.

[0062] Relative to Figure 2 the way shown Figure 3 Although the way shown can further improve the heat dissipation performance and prevent the top of the chip 12 from being damaged by external forces, since the thermal conductive adhesive 15 is required to achieve the thermal contact between the chip 12 and the heat dissipation cover 14, it is impossible to take into account both the heat dissipation performance of the chip 12 and the stability of the adhesive fixation of the heat dissipation cover 14. This is because the adhesive force of the thermal conductive adhesive 15 is negatively correlated with the thermal conductivity. If a thermal conductive adhesive 15 with high thermal conductivity is used to adhesively fix the heat dissipation cover plate 14, due to the insufficient adhesive force of the thermal conductive adhesive 14, it is easy to cause the problem of the detachment of the thermal conductive cover plate 15; on the contrary, if a thermal conductive adhesive 14 with strong adhesive force is used, although the problem of the detachment of the thermal conductive cover plate 15 can be prevented, it will lead to a weakening of the heat dissipation performance of the chip 12.

[0063] In view of this, the embodiments of the present application provide an FCCSP structure and a chip packaging method. In the technical solution of the present application, a heat dissipation cover in thermal contact with the top of the chip is provided, which can improve the heat dissipation performance of the chip. In addition, at least part of the heat dissipation cover is embedded in the plastic package structure, and the plastic package structure is used to fix the heat dissipation cover, so as to prevent the heat dissipation cover from falling off. Since the heat dissipation cover is fixed by the plastic package structure, a thermal conductive adhesive with a high thermal conductivity coefficient can be used between the heat dissipation cover and the chip to improve the heat dissipation performance of the chip.

[0064] In order to make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0065] Reference Figure 4 as shown Figure 4 is a schematic diagram of an FCCSP structure provided by an embodiment of the present application. The FCCSP structure shown includes:

[0066] A packaging substrate 11;

[0067] A chip 12, the bottom of the chip 12 is fixed on the surface of the packaging substrate 11;

[0068] A heat dissipation cover 14, the heat dissipation cover 14 is in thermal contact with the top of the chip 12;

[0069] The plastic package structure 13, and the heat dissipation cover 14 is at least partially embedded in the plastic package structure 14; the plastic package structure 13 is used to fix the heat dissipation cover 14; the plastic package structure 13 at least exposes the outer surface of the part of the heat dissipation cover 14 that is in thermal contact with the top of the chip.

[0070] In the FCCSP structure provided by the embodiment of the present application, a heat dissipation cover 14 is provided. The heat dissipation cover 14 is in thermal contact with the top of the chip 12, which can improve the heat dissipation performance of the chip 12. In addition, at least part of the heat dissipation cover 14 is embedded in the plastic package structure 13, and the plastic package structure 13 exposes the outer surface of the part of the heat dissipation cover 14 that is in thermal contact with the top of the chip, which is convenient for the heat dissipation cover 14 to dissipate heat to the outside, and can fix the heat dissipation cover 14 through the plastic package structure 13 to prevent the heat dissipation cover 14 from falling off.

[0071] In the embodiment of the present application, a thermal conductive adhesive 15 is filled between the heat dissipation cover 14 and the chip 12 to achieve good contact between the chip 12 and the heat dissipation cover 14.

[0072] Optionally, one side surface of the packaging substrate 11 for fixing the chip 12 has an interconnection circuit, and the other side surface has solder balls 111. The solder balls 111 are used for connecting the FCCSP structure to an external circuit. The top of the chip 12 has chip pins 121, and the chip pins 121 are fixedly connected to the interconnection circuit on the surface of the packaging substrate 11. The interconnection circuit is connected to the requirements 111 on the other side surface through the conductive vias in the packaging substrate 11.

[0073] In the conventional FCCSP structure, it is impossible to balance the heat dissipation performance of the chip 12 and the bonding and fixing stability of the heat dissipation cover 14. In the technical solution of the embodiment of the present application, the plastic package structure 13 is used to fix the heat dissipation cover 14, so the heat dissipation cover 14 and the chip 12 can be in thermal contact with the thermal conductive adhesive 15 with high thermal conductivity, without considering the bonding force of the thermal conductive adhesive 15.

[0074] In an implementation manner of the embodiment of the present application, the thermal conductivity of the thermal conductive adhesive 15 is greater than 6.7 W / (m·K). Correspondingly Figure 3 For the shown FCCSP structure, the thermal conductivity of the thermal conductive adhesive 15 used is generally about 1.9 W / (m·K), and the thermal conductivity is small, which affects the heat dissipation performance of the chip 12. If a thermal conductive adhesive 15 with a larger thermal conductivity is used, it will cause insufficient bonding force of the thermal conductive adhesive 14, resulting in the problem that the heat dissipation cover 14 is likely to fall off. As described above, in the embodiment of the present application, since the plastic package structure 13 can be reused to fix the heat dissipation cover 14, it is not necessary to consider the bonding force of the thermal conductive adhesive 15, and the thermal conductive adhesive 15 with the largest thermal conductivity on the market can be used to achieve thermal contact between the chip 12 and the heat dissipation cover 14, and the problem of the heat dissipation cover 14 falling off will not occur.

[0075] In Figure 4In the shown manner, the heat dissipation cover 14 has a flat plate structure, and the edge of the flat plate structure is flush with the edge of the chip 12. Among them, the edge of the flat plate structure being flush with the edge of the chip 12 includes: in the direction perpendicular to the plane where the packaging substrate 11 is located, the edge of the flat plate structure coincides with or approximately coincides with the edge of the chip 12.

[0076] For the heat dissipation cover 14 corresponding to the flat plate structure, on the side facing away from the chip 12, a plastic encapsulation structure 13 can be provided to be flush with or approximately flush with the surface of the heat dissipation cover 14.

[0077] In the FCCSP structure provided by the embodiments of the present application, the shape of the heat dissipation cover 14 can be set based on requirements, not limited to Figure 4 the shown flat plate structure.

[0078] Refer to Figure 5 as shown, Figure 5 which is a schematic diagram of another FCCSP structure provided by the embodiments of the present application. Different from Figure 4 the shown manner, Figure 5 in the shown FCCSP structure, the heat dissipation cover 14 includes: a heat-conducting top 141 and a heat-conducting side wall 142 surrounding the heat-conducting top 141. The heat-conducting top 141 and the heat-conducting side wall 142 form a receiving cavity; at least a part of the chip 12 is located in the receiving cavity; the part of the chip 12 located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity. In this manner, in order to ensure the thermal contact effect between the heat dissipation cover 14 and the chip 12, it can be set that the entire surface of the receiving cavity is in thermal contact with the chip 12 through a thermal conductive adhesive 15.

[0079] In Figure 5 the shown manner, the heat dissipation cover 14 includes: a heat-conducting top 141 and a heat-conducting side wall 142 surrounding the heat-conducting top 141. It can increase the thermal contact area between the heat dissipation cover 14 and the chip 12, and further improve the heat dissipation performance of the chip 12. Moreover, based on the heat-conducting side wall 142, the heat dissipation cover 14 can be more deeply embedded in the plastic encapsulation structure 13, improving the fixing effect of the plastic encapsulation structure 13 on the heat dissipation cover 14.

[0080] When using Figure 5 the heat dissipation cover 14 in the shown manner, it can be set that the plastic encapsulation structure 13 completely covers the heat-conducting side wall 142. At this time, as Figure 5 shown, on the side facing away from the chip 12, the plastic encapsulation structure 13 is flush with or approximately flush with the surface of the heat-conducting top 141.

[0081] Refer to Figure 6 as shown, Figure 6 which is a schematic diagram of yet another FCCSP structure provided by the embodiments of the present application. Figure 6 The shown FCCSP structure and Figure 5The FCCSP structure shown uses the same heat dissipation cover 14, and the heat dissipation cover 14 includes: a heat-conducting top 141 and a heat-conducting side wall 142 surrounding the heat-conducting top 141. Different from Figure 5 the way shown is that Figure 6 in the FCCSP structure shown, a part of the heat-conducting side wall 142 of the plastic package structure 13 is exposed.

[0082] In Figure 6 the way shown, a part of the heat-conducting side wall 142 close to the packaging substrate 11 is embedded in the plastic package structure 13, and another part of the heat-conducting side wall 142 close to the heat-conducting top 141 is exposed from the plastic package structure 13. The part of the heat-conducting side wall 142 exposed from the plastic package structure 13 is more conducive to dissipating heat to the outside of the FCCSP structure, improving the heat dissipation performance.

[0083] Referring to Figure 7 shown, Figure 7 is a schematic diagram of another FCCSP structure provided by an embodiment of the present application. Different from Figure 4 the way shown is that Figure 7 in the FCCSP structure shown, the heat dissipation cover 14 includes: a heat-conducting top 141 and a heat-conducting bottom 143 surrounding the heat-conducting top 141. There is a heat-conducting side wall 142 between the heat-conducting bottom 143 and the heat-conducting top 141. The heat-conducting top 141 and the heat-conducting side wall 142 form a receiving cavity, and at least part of the chip 12 is located in the receiving cavity; the part of the chip 12 located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity; the heat-conducting bottom 143 is embedded in the plastic package structure 13, and the heat-conducting bottom 143 extends in a direction away from the side wall of the chip, and the heat-conducting bottom 143 is fixed to the packaging substrate 11 through the plastic package structure 13. In this way, in order to ensure the thermal contact effect between the heat dissipation cover 14 and the chip 12, it can be set that the entire surface of the receiving cavity is in thermal contact with the chip 12 through the thermal conductive adhesive 15.

[0084] In Figure 7 the way shown, not only can the heat-conducting side wall 142 be used to increase the thermal contact area between the heat dissipation cover 14 and the chip 12, improving the heat dissipation performance of the chip 12, but also the heat-conducting bottom 143 can be used to increase the contact area between the heat dissipation cover 14 and the plastic package structure 13, thereby improving the fixing effect of the plastic package structure 13 on the heat dissipation cover 14.

[0085] When using the heat dissipation cover 14 in Figure 7 the way shown, it can be set that the plastic package structure 13 completely covers the heat-conducting bottom 143 and the heat-conducting side wall 142. At this time, as Figure 7 shown, on the side facing away from the chip 12, the surface of the plastic package structure 13 is flush or approximately flush with the surface of the heat-conducting top 141.

[0086] Referring to Figure 8 shown, Figure 8Another schematic diagram of the FCCSP structure provided by the embodiment of the present application Figure 8 The shown FCCSP structure and Figure 7 The shown FCCSP structure adopt the same heat dissipation cover 14, and the heat dissipation cover 14 includes: a heat conduction top 141, a heat conduction side wall 142 and a heat conduction bottom 143. Different from Figure 7 The shown manner is that Figure 8 In the shown FCCSP structure, a part of the heat conduction side wall 142 of the plastic package structure 13 is exposed

[0087] In Figure 8 In the shown FCCSP structure, a part of the heat conduction side wall 142 close to the packaging substrate 11 is embedded into the plastic package structure 13, and another part of the heat conduction side wall 142 close to the heat conduction top 141 is exposed from the plastic package structure 13. A part of the heat conduction side wall 142 exposed from the plastic package structure 13 is more convenient for heat to dissipate to the outside of the FCCSP structure, improving the heat dissipation performance

[0088] Optionally, in Figure 8 In the shown manner, the plastic package structure 143 is set to completely cover the heat conduction bottom 143 to ensure the fixing effect of the plastic package structure 13 on the heat dissipation cover 14. At least the heat conduction bottom 143 is embedded into the plastic package structure 13, which can prevent the heat dissipation cover 14 from warping

[0089] In the embodiment of the present application, the heat dissipation cover 14 is an integrally formed structure. The heat dissipation cover can be any one of a metal heat dissipation cover, a silicon carbide heat dissipation cover and a ceramic heat dissipation cover. The heat dissipation cover 14 can be made of any high thermal conductivity material, and the material of the heat dissipation cover 14 can be set based on requirements. The embodiment of the present application does not limit this

[0090] In any of the above embodiments, the plastic package structure 13 can be the same layer of plastic encapsulation layer

[0091] When the heat dissipation cover 14 at least includes: a heat conduction top 141 and a heat conduction side wall 142, the plastic package structure 13 can also include two layers of plastic encapsulation layers. At this time, the FCCSP structure is as Figures 9 - 11 shown

[0092] Referring to Figure 9 shown Figure 9Another schematic diagram of the FCCSP structure provided by the embodiment of the present application. In this method, the encapsulation structure 13 at least includes: a first encapsulation glue layer 131, which is on the same side surface of the encapsulation substrate 11 as the chip 12, fills the gap between the heat-conducting bottom 143 and the encapsulation substrate 11, and fills the gap between the bottom of the chip 12 and the encapsulation substrate 11; a second encapsulation glue layer 12, which covers the heat-conducting bottom 143 and surrounds the heat-conducting side wall 142; wherein, the coefficient of thermal expansion (CTE) of the first encapsulation glue layer 131 is different from that of the second encapsulation glue layer 132. In this method, the second encapsulation glue layer 142 completely covers the heat-conducting side wall 142.

[0093] Refer to Figure 10 as shown in Figure 10 Another schematic diagram of the FCCSP structure provided by the embodiment of the present application. Different from the Figure 9 method shown, the second encapsulation glue layer 142 exposes a part of the heat-conducting side wall 142 to improve the heat dissipation performance.

[0094] In Figure 9 and Figure 10 the method shown, when the heat dissipation cover 14 includes: a heat-conducting top 141, a heat-conducting side wall 142 and a heat-conducting bottom 143, a schematic diagram of the FCCSP structure with a double-layer encapsulation glue layer is illustrated.

[0095] Refer to Figure 11 as shown in Figure 11 Another schematic diagram of the FCCSP structure provided by the embodiment of the present application. In this method, the heat dissipation cover 14 includes: a heat-conducting top 141 and a heat-conducting side wall 142, and the encapsulation structure 13 at least includes: a first encapsulation glue layer 131, which fills the gap between the heat-conducting bottom 143 and the encapsulation substrate 11, and fills the gap between the bottom of the chip 12 and the encapsulation substrate 11; a second encapsulation glue layer 12, which surrounds the heat-conducting side wall 142. Similarly, the second encapsulation glue layer 12 can be set to completely cover the heat-conducting side wall 142 to be flush with the heat-conducting top 141, or the second encapsulation glue layer 12 can be set to expose a part of the heat-conducting side wall 142.

[0096] In Figures 9 - 11 the method shown, the heat dissipation cover 14 at least includes: a heat-conducting top 141 and a heat-conducting side wall 142. The encapsulation structure 13 is set to include a first encapsulation glue layer 131 and a second encapsulation glue layer 132, which can not only reduce the stress in the product by selecting an encapsulation glue layer with an appropriate coefficient of thermal expansion to prevent warping problems. Moreover, in the manufacturing process of the FCCSP structure, after the chip 12 is fixed on the encapsulation substrate 11, the first encapsulation glue layer 131 can be formed first, and then based on the first encapsulation glue layer 131, the heat dissipation cover 14 can be set above the chip 12, using the first encapsulation glue layer 131 as the bearing support body of the heat dissipation cover 14 to play a role in stabilizing the heat dissipation cover 14.

[0097] In the process of plastic encapsulating the chip 12, a high-temperature process is required. Since the thermal expansion coefficient of the packaging substrate 11 is greater than that of the chip 12, the temperature change during the plastic encapsulation process will cause different degrees of deformation stress between the chip 12 and the packaging substrate 11, which is likely to cause the chip 11 to warp. In addition, the heat dissipation cover 14 is made of a material with a relatively large stiffness and good heat dissipation performance. The heat dissipation cover 14 with a relatively large stiffness is not easily deformed. When the packaging substrate 11 is deformed to a large extent, the heat dissipation cover 14 will generate a stress that inhibits the deformation of the packaging substrate 11 when the packaging substrate 11 deforms, and this stress is likely to cause the heat dissipation cover 14 to warp. In the embodiment of the present application, the plastic encapsulation structure 13 is provided to include a first plastic encapsulation layer 131 and a second plastic encapsulation layer 132 with different thermal expansion coefficients, which can release the stress in the FCCSP structure manufacturing process based on the two plastic encapsulation layers 131 with different thermal expansion coefficients, and prevent the chip 12 and / or the heat dissipation cover 14 from warping.

[0098] It should be noted that in the FCCSP structure, when any of the above heat dissipation covers 14 is used, whether it is a plastic encapsulation structure 13 with a single plastic encapsulation layer or a plastic encapsulation structure 13 with a double plastic encapsulation layer, it can offset a part of the warping stress caused by the packaging substrate 11 based on the gravity of the heat dissipation cover 14, and prevent the chip 12 and / or the heat dissipation cover 14 from warping.

[0099] When the heat dissipation cover 14 includes a heat-conducting bottom 143, in the FCCSP structure, when any of the above heat dissipation covers 14 is used, whether it is a plastic encapsulation structure 13 with a single plastic encapsulation layer or a plastic encapsulation structure 13 with a double plastic encapsulation layer, it can further offset a part of the warping stress caused by the packaging substrate 11 based on the weight of the heat-conducting bottom 143. On this basis, when the plastic encapsulation structure 13 with a double plastic encapsulation layer is used, the warping problem can be better prevented.

[0100] In an implementation manner of the embodiment of the present application, the thermal expansion coefficient of the chip 12 is set to a 1 , the thermal expansion coefficient of the packaging substrate 11 is a 2 , the thermal expansion coefficient of the first plastic encapsulation layer 131 is a 3 , and the thermal expansion coefficient of the second plastic encapsulation layer 132 is a 4 ; where a 1 < a 3 < a 2 , and a 3 - a 1 < a 2 - a 3 ; and / or, a 1 < a 4 < a 2 , and a 4-a 1 > a 2 -a 4 。

[0101] Based on the material properties, the coefficient of thermal expansion a of the encapsulation substrate 11 2 is generally much greater than the coefficient of thermal expansion a of the chip 12 1 , and the coefficient of thermal expansion of the plastic encapsulation layer is between a 1 and a 2 . Therefore, when the temperature changes between high and low, the FCCSP structure is prone to generate large stresses due to the mismatch in the coefficients of thermal expansion of the chip 12 and the encapsulation substrate 11, resulting in warping of the chip 12

[0102] In the embodiments of the present application, a is set such that 1 < a 3 < a 2 , and a 3 -a 1 < a 2 -a 3 , such that a 3 is between a 1 and a 2 , and a 3 is closer to a 1 . The first plastic encapsulation layer 131 can better buffer the stress exerted by the encapsulation substrate 11 on the chip 12, effectively preventing the chip 12 from warping. For example, when a 2 = 20 / °C and a 1 = 3 / °C, a 3 can be 9 / °C

[0103] In the embodiments of the present application, a is set such that 1 < a 4 < a 2 , and a 4 -a 1 > a 2 -a 4 , such that a 4 is between a 1 and a 2 , and a 4 is closer to a 2 . The second plastic encapsulation layer 132 can generate relatively consistent stress with the encapsulation substrate 11, so that the stress between the second plastic encapsulation layer 132 and the encapsulation substrate 11 cancels each other out up and down, thereby suppressing the warping of the chip 12 and the heat dissipation cover 14

[0104] Optionally, a is set such that 4 > a 3 , for example, a 3 can be set to 9 / °C, a 4= 18 / °C. It should be noted that the coefficient of thermal expansion of each structure can be set based on requirements. In the embodiments of the present application, for a 1 、a 2 、a 3 and a 4 no specific values are limited.

[0105] By adjusting the thickness of the second encapsulation layer 132, it is convenient to adjust the stress and improve the reliability of the FCCSP structure. Since the heat-conducting bottom 143 is sandwiched between two encapsulation layers, and the weight of the heat-conducting bottom 143 is evenly distributed around the chip 12, the heat-conducting bottom 143 increases the contact area between the upper second encapsulation layer 132 and the heat dissipation cover 14, and has a better fixing effect on the heat dissipation cover 14, so that the thickness adjustment range of the second encapsulation layer 132 is increased. On the premise of ensuring that the second encapsulation layer 132 covers the heat-conducting bottom 143, the thickness of the second encapsulation layer 132 can be adjusted more significantly, thereby increasing the corresponding stress adjustment range, and the design requirements for the packaging substrate 11 and the chip 12 in the product design process can be reduced.

[0106] In the FCCSP structure provided by the embodiments of the present application, on the side of the FCCSP structure facing away from the packaging substrate 11, the height of the heat dissipation cover 14 relative to the packaging substrate 11 is flush with the height of the encapsulation structure 13 relative to the packaging substrate 11. This method can make the surface of the FCCSP structure on the side facing away from the packaging substrate 11 relatively flat.

[0107] In other methods, on the side of the FCCSP structure facing away from the packaging substrate 11, the height of the heat dissipation cover 14 relative to the packaging substrate 11 is greater than the height of the encapsulation structure 13 relative to the packaging substrate 11. This method can increase the surface area of the heat dissipation cover 14 exposed outside the encapsulation structure 13 and improve the heat dissipation performance.

[0108] The surface of the heat dissipation cover 14 in thermal contact with the chip 12 is provided with a plurality of first micro-protrusions, and / or the surface of the chip 12 in thermal contact with the heat dissipation cover 14 is provided with a plurality of second micro-protrusions. The heat dissipation cover 14 and the chip 12 are in thermal contact through the thermal conductive adhesive 25. The first micro-protrusions and / or the second micro-protrusions can increase the thermal contact area between the heat dissipation cover 14 and the chip 12, thereby improving the heat dissipation performance.

[0109] The surface of the heat dissipation cover 14 on the side facing away from the chip 12 is provided with a plurality of surface micro-structures. Providing surface micro-structures on the part of the heat dissipation cover 14 in thermal contact with the top of the chip can increase the heat dissipation area of the exposed part of the heat dissipation cover 14, thereby improving the heat dissipation performance.

[0110] Further, it is also possible to provide that the portion of the heat dissipation cover 14 embedded in the plastic encapsulation structure 13 has a surface microstructure, which can increase the contact area with the plastic encapsulation structure 13 based on the surface microstructure, so that the plastic encapsulation structure 13 has a greater adhesion on the surface of this portion of the heat dissipation cover 14, and improve the fixing effect of the plastic encapsulation structure 13 on the heat dissipation cover 14.

[0111] Another embodiment of the present application further provides a chip packaging method for preparing the FCCSP structure provided by any one of the above embodiments. The chip packaging method is as Figure 12 shown.

[0112] Refer to Figure 12 shown, Figure 12 which is a process flow chart of a chip packaging method provided by an embodiment of the present application. Combining with the FCCSP structure provided by the above embodiment, the chip packaging method includes:

[0113] Step S11: Provide a packaging substrate 11.

[0114] Step S12: Fix the chip 12 on the surface of the packaging substrate 11.

[0115] Step S13: Provide a heat dissipation cover 14 in thermal contact with the top of the chip 12 to form a plastic encapsulation structure 13.

[0116] Among them, the heat dissipation cover 14 is at least partially embedded in the plastic encapsulation structure 13; the plastic encapsulation structure 13 is used to fix the heat dissipation cover 14; the plastic encapsulation structure 13 at least exposes the outer surface of the portion of the heat dissipation cover 14 in thermal contact with the top of the chip.

[0117] Based on this chip packaging method, the FCCSP structure provided by the above embodiment can be prepared, the preparation process is simple, and the manufacturing cost is low. Moreover, the prepared FCCSP structure can improve the heat dissipation performance of the chip 12 and can effectively prevent the problem of the heat dissipation cover 14 falling off.

[0118] As described above, in one embodiment, the heat dissipation cover 14 includes a heat-conducting top 141 and a heat-conducting bottom 143 surrounding the heat-conducting top 141. There is a heat-conducting side wall 142 between the heat-conducting bottom 143 and the heat-conducting top 141. The heat-conducting top 141 and the heat-conducting side wall 142 form a receiving cavity. At least a part of the chip 12 is located in the receiving cavity. The part of the chip 12 located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity. At this time, the method for forming the plastic package structure 13 includes: after fixing the chip 12 on the surface of the packaging substrate 11, before setting the heat dissipation cover 14, forming a first plastic package layer 131. The first plastic package layer 131 is on the same side surface of the chip 12 and the packaging substrate 11, fills the gap between the heat-conducting bottom 143 and the packaging substrate 11, and fills the gap between the bottom of the chip 12 and the packaging substrate 11. After setting the heat dissipation cover 14 covering the chip 12, forming a second plastic package layer 132. The second plastic package layer 132 covers the heat-conducting bottom 143 and surrounds the heat dissipation cover 14. Among them, the coefficients of thermal expansion of the first plastic package layer 131 and the second plastic package layer 132 are different.

[0119] Next, in combination with the product structures in different process steps, the method for fabricating Figure 9 the chip package with the FCCSP structure shown is further described.

[0120] Refer to Figures 13 - 17 shown in Figures 13 - 17 FIG. which is a schematic diagram of the product structure of a chip package method provided by an embodiment of the present application in different process steps. The chip package method includes:

[0121] Step S21: As Figure 13 shown, provide the packaging substrate 11.

[0122] Step S22: As Figure 14 shown, fix the chip 12 on the surface of the packaging substrate 11.

[0123] Step S23: As Figure 15 shown, form the first plastic package layer 131. The first plastic package layer 131 covers the side surface of the packaging substrate 11 where the chip 12 is provided, and fills the gap between the chip 12 and the plastic packaging substrate 11.

[0124] Among them, relative to the plastic packaging substrate 11, the height of the chip 12 is greater than the height of the first plastic package layer 131, and the height difference between the two is greater than the thickness of the heat-conducting bottom 143, so that the heat dissipation cover 14 can surround at least part of the side wall of the chip 12.

[0125] Step S24: As Figure 16 shown, set the heat dissipation cover 14 in thermal contact with the chip 12. The heat-conducting bottom 143 is adhesively fixed on the surface of the plastic packaging substrate 11 based on the first plastic package layer 131.

[0126] Step S25: As shown in Figure 17 , a second encapsulation glue layer 132 is formed on the surfaces of the first encapsulation glue layer 131 and the heat-conducting bottom 143. The second encapsulation glue layer 132 surrounds the heat-conducting sidewall 142 and is flush with the surface of the heat-conducting top 141.

[0127] Finally, ball implantation is performed on the other side of the encapsulation substrate 11 away from the chip 12, and a plurality of solder balls 111 are formed on this surface to form an FCCSP structure as shown in Figure 9 .

[0128] Next, in combination with the product structures in different process steps, the chip encapsulation method for preparing the Figure 7 shown FCCSP structure will be further described.

[0129] Referring to Figures 18 - 19 shown, Figures 18 - 19 FIG. is a schematic diagram of the product structure in different process steps of another chip encapsulation method provided by an embodiment of the present application. The chip encapsulation method includes:

[0130] Step S31: As shown in Figure 13 , the encapsulation substrate 11 is provided.

[0131] Step S32: As shown in Figure 14 , the chip 12 is fixed on the surface of the encapsulation substrate 11.

[0132] Step S33: As shown in Figure 18 , a heat dissipation cover 14 in thermal contact with the chip 12 is arranged above the chip 12.

[0133] Step S34: As shown in Figure 19 , the chip 12 and the heat dissipation cover 14 are encapsulated and protected based on the same layer of encapsulation glue layer, and this layer of encapsulation glue layer serves as the encapsulation structure 13.

[0134] Finally, ball implantation is performed on the other side of the encapsulation substrate 11 away from the chip 12, and a plurality of solder balls 111 are formed on this surface to form an FCCSP structure as shown in Figure 7 .

[0135] In the Figures 13 - 19 shown manner, the manufacturing process flows of the Figure 7 and Figure 9 shown FCCSP structures are illustrated. For the FCCSP structures provided by other embodiments of the present application, they can all be prepared based on the same principle, and the embodiments of the present application will not elaborate on them one by one.

[0136] In this specification, the various embodiments are described in a progressive, or parallel, or a combination of progressive and parallel manners. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0137] It should be noted that in the description of this application, it should be understood that the descriptions of the drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structures. Additionally, for the sake of understanding and easy description, some layers, films, panels, regions, etc. may be exaggerated in thickness in the drawings. At the same time, it can be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element can be directly on the other element or there may be intermediate elements. Additionally, "on" means positioning an element on or below another element, but essentially does not mean positioning on the upper side of another element according to the direction of gravity.

[0138] The orientation or positional relationships indicated by terms such as "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and thus should not be construed as a limitation to this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be intermediate components present simultaneously.

[0139] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including", or any other variant thereof is intended to cover non-exclusive inclusion, such that an article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the article or device including the above elements.

[0140] The above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An FCCSP structure, comprising: a packaging substrate; a chip, the bottom of the chip being fixed on the surface of the packaging substrate; a heat dissipation cover, the heat dissipation cover being in thermal contact with the top of the chip; a plastic encapsulation structure, at least part of the heat dissipation cover being embedded in the plastic encapsulation structure; the plastic encapsulation structure being used to fix the heat dissipation cover; the plastic encapsulation structure at least exposing the outer surface of the part where the heat dissipation cover is in thermal contact with the top of the chip.

2. The FCCSP structure according to claim 1, wherein a thermal conductive adhesive is filled between the heat dissipation cover and the chip, and the thermal conductivity of the thermal conductive adhesive is greater than 6.7 W / (m·K).

3. The FCCSP structure according to claim 1, wherein the heat dissipation cover is a flat plate structure, and the flat plate structure is flush with the edge of the chip.

4. The FCCSP structure according to claim 1, the heat dissipation cover comprising: a heat conductive top and a heat conductive side wall surrounding the heat conductive top, the heat conductive top and the heat conductive side wall forming a receiving cavity; at least part of the chip being located in the receiving cavity; the part of the chip located in the receiving cavity being in thermal contact with the inner surface of the receiving cavity.

5. The FCCSP structure according to claim 1, the heat dissipation cover comprising: a heat conductive top and a heat conductive bottom surrounding the heat conductive top, there being a heat conductive side wall between the heat conductive bottom and the heat conductive top, the heat conductive top and the heat conductive side wall forming a receiving cavity, at least part of the chip being located in the receiving cavity; the part of the chip located in the receiving cavity being in thermal contact with the inner surface of the receiving cavity; the heat conductive bottom being embedded in the plastic encapsulation structure, the heat conductive bottom extending in a direction away from the side wall of the chip, and the heat conductive bottom being fixed to the packaging substrate through the plastic encapsulation structure.

6. The FCCSP structure according to claim 5, wherein the plastic encapsulation structure is a single layer of plastic encapsulation glue layer; or, the plastic encapsulation structure at least comprises: a first plastic encapsulation glue layer, the first plastic encapsulation glue layer being on the same side surface of the chip and the packaging substrate, filling the gap between the heat conductive bottom and the packaging substrate, and filling the gap between the bottom of the chip and the packaging substrate; a second plastic encapsulation glue layer, the second plastic encapsulation glue layer covering the heat conductive bottom and surrounding the heat conductive side wall; wherein, the thermal expansion coefficients of the first plastic encapsulation glue layer and the second plastic encapsulation glue layer are different.

7. The FCCSP structure according to claim 6, wherein the coefficient of thermal expansion of the chip is a 1 , the coefficient of thermal expansion of the packaging substrate is a 2 , the coefficient of thermal expansion of the first encapsulant layer is a 3 , the coefficient of thermal expansion of the second encapsulant layer is a 4 ; Wherein, a 1 <a 3 <a 2 and a 3 -a 1 <a 2 -a 3 ; and / or, a 1 <a 4 <a 2 and a 4 -a 1 >a 2 -a 4 .

8. The FCCSP structure according to any one of claims 1-7, on the side of the FCCSP structure facing away from the packaging substrate, the height of the heat dissipation cover relative to the packaging substrate is flush with the height of the plastic encapsulation structure relative to the packaging substrate, or the height of the heat dissipation cover relative to the packaging substrate is greater than the height of the plastic encapsulation structure relative to the packaging substrate.

9. A chip packaging method, comprising: providing a packaging substrate; fixing a chip on the surface of the packaging substrate; providing a heat dissipation cover in thermal contact with the top of the chip to form a plastic encapsulation structure; Wherein, at least part of the heat dissipation cover is embedded in the plastic encapsulation structure; the plastic encapsulation structure is used to fix the heat dissipation cover; the plastic encapsulation structure at least exposes the outer surface of the part of the heat dissipation cover that is in thermal contact with the top of the chip.

10. The chip packaging method according to claim 9, the heat dissipation cover comprises: a heat-conducting top and a heat-conducting bottom surrounding the heat-conducting top, there is a heat-conducting side wall between the heat-conducting bottom and the heat-conducting top, and the heat-conducting top and the heat-conducting side wall form a receiving cavity; at least part of the chip is located in the receiving cavity; the part of the chip located in the receiving cavity is in thermal contact with the inner surface of the receiving cavity; The method for forming the plastic encapsulation structure includes: after fixing the chip on the surface of the packaging substrate and before setting the heat dissipation cover, forming a first plastic encapsulation glue layer, the first plastic encapsulation glue layer is on the same side surface of the chip as the packaging substrate, filling the gap between the heat-conducting bottom and the packaging substrate, and filling the gap between the bottom of the chip and the packaging substrate; after setting the heat dissipation cover covering the chip, forming a second plastic encapsulation glue layer, the second plastic encapsulation glue layer covers the heat-conducting bottom and surrounds the heat-conducting side wall; wherein, the thermal expansion coefficients of the first plastic encapsulation glue layer and the second plastic encapsulation glue layer are different.

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