Stacked package structure and method for manufacturing stacked package structure

Abstract

The application provides a kind of stack package structure and the preparation method of stack package structure, it is related to chip packaging technical field, the stack package structure includes first substrate, package chip, second substrate, double-layer solder ball and plastic encapsulation layer.Double-layer solder ball is located in the back of second substrate, double-layer solder ball includes core ball and outer solder layer.Compared with prior art, the first support fence is embedded into outer solder layer in the application, which greatly improves the bonding strength of outer solder layer and first pad, thereby effectively improving the welding strength and reducing the risk of bridging or false welding due to substrate warping.Also, the tin content of outer solder layer is evenly distributed, and it will not overflow too much to cause bridging.Meanwhile, due to the support of the first support fence, the core ball can be supported, effectively reducing the solder ball collapse phenomenon, thereby ensuring that the gap between the first substrate and the second substrate meets the plastic encapsulation requirement, increasing the plastic encapsulation space and reducing the plastic encapsulation cavity phenomenon.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip packaging, in particular to a stacked packaging structure and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the semiconductor industry, the miniaturization of electronic products leads to higher and higher packaging density, and communication products need to meet high bandwidth performance. The POP (Package on Package) stacked structure is widely used in the semiconductor industry, which can package storage chips and processor chips together to meet high bandwidth performance and achieve miniaturization. It has the advantages of small product size, superior product performance, fast signal transmission frequency, etc. The product is mainly used in miniaturized and thinned communication terminal products.

[0003] The existing POP stacked structure usually uses copper core tin balls for welding in the substrate pad interconnection structure, which can greatly reduce the risk of tin ball welding collapse bridging between tin balls, thereby meeting the high-density interconnection structure. However, during the copper core ball welding process, due to the use of different materials in different layers of the package, the thermal expansion coefficients of the materials are different, which causes the substrate / adapter plate to warp during reflow welding, resulting in bridging or false welding between tin balls. In addition, during the welding process, the copper core ball in the inner layer is not supported and limited, and is prone to deviation. Moreover, due to the large opening width of the pads on the substrate, the tin balls are prone to melting and collapsing during welding, which makes the substrate spacing too small and the plastic encapsulation space small, and the plastic encapsulation is prone to void phenomenon. SUMMARY

[0004] The purpose of the present application is to provide a stacked packaging structure and a preparation method thereof, which can effectively improve the welding strength, reduce the risk of bridging or false welding, and effectively increase the plastic encapsulation space to alleviate the plastic encapsulation void phenomenon.

[0005] In a first aspect, the present application provides a stacked packaging structure, comprising:

[0006] A first substrate is provided with a first pad and a second pad on the front surface, the first pad is arranged around the second pad, and a first support fence is further arranged on the first pad;

[0007] A packaging chip is attached to the first substrate and electrically connected to the second pad;

[0008] A second substrate is located on the side of the packaging chip away from the first substrate, and a third pad is arranged on the back surface of the second substrate, and the third pad corresponds to the first pad respectively;

[0009] A double-layer solder ball is disposed on the back surface of the second substrate, the double-layer solder ball includes a core ball and an outer solder layer, the outer solder layer covers the core ball and is connected to the third pad and the first pad, and the outer solder layer covers the first support fence, the core ball corresponds to abut on the first support fence, so that the core ball is spaced apart from the first pad;

[0010] A plastic sealing layer is formed between the first substrate and the second substrate and covers the package chip and the double-layer solder ball.

[0011] In an optional embodiment, the front surface of the first substrate is further provided with a first solder resist layer, the first solder resist layer covers the first pad and forms a first solder opening partially exposing the first pad, the first support fence is disposed on the first pad in the first solder opening, and the outer solder layer fills the first solder opening and contacts the first pad in the first solder opening.

[0012] In an optional embodiment, the first support fence is distributed along a circumference, and an inner diameter of the first support fence is smaller than an outer diameter of the core ball, so that the core ball is supported by the first support fence.

[0013] In an optional embodiment, an outer diameter of the first support fence is smaller than a width of the first solder opening, so that the first support fence is spaced apart from an edge of the first solder opening.

[0014] In an optional embodiment, the first support fence is distributed along an edge of the first solder opening and partially covers a peripheral edge of the first solder opening.

[0015] In an optional embodiment, a first groove is disposed in a middle portion of an end surface of the first support fence, and the outer solder layer fills the first groove.

[0016] In an optional embodiment, an edge of the first support fence is provided with a first stepped groove, the first stepped groove extends to an outer sidewall of the first support fence, so that an outer edge of the first support fence forms a first stepped structure.

[0017] In an optional embodiment, the back surface of the second substrate is further provided with a second solder resist layer, the second solder resist layer covers the third pad and forms a second solder opening partially exposing the third pad, and the outer solder layer fills the second solder opening and contacts the third pad in the second solder opening.

[0018] In an optional embodiment, the third pad is further provided with a second support fence, which is distributed along the edge of the second welding opening and partially covers the periphery of the second welding opening.

[0019] In an optional embodiment, a second groove is arranged in the middle of the end surface of the second support fence, and the outer solder layer is filled in the second groove.

[0020] In an optional embodiment, a second stepped groove is arranged in the edge of the second support fence, which extends to the outer sidewall of the second support fence, so that the outer edge of the second support fence forms a second stepped structure.

[0021] In an optional embodiment, the third pad in the second welding opening is further provided with a support conductive column protruding towards the second substrate, which is connected to the inner core ball.

[0022] In an optional embodiment, the support conductive column corresponds to the center of the first support fence, so that the support conductive column is arranged in a staggered manner with the first support fence.

[0023] In an optional embodiment, the stacked package structure further comprises a packaging device, which is attached to the front surface of the second substrate.

[0024] In a second aspect, the present application provides a preparation method of a stacked package structure, which is used for preparing the stacked package structure as described in the foregoing embodiments, and the preparation method comprises the following steps:

[0025] providing a first substrate, wherein the front surface of the first substrate is provided with a first pad and a second pad, and the first pad is arranged around the second pad;

[0026] forming a first support fence on the first pad;

[0027] attaching a packaging chip on the first substrate, wherein the packaging chip is electrically connected to the second pad;

[0028] attaching a second substrate with a double-layer solder ball formed on the back surface on the first substrate, wherein the back surface of the second substrate is provided with a third pad corresponding to the first pad respectively, the double-layer solder ball comprises an inner core ball and an outer solder layer, the outer solder layer covers the inner core ball and is connected to the third pad and the first pad at the same time, and the outer solder layer covers the first support fence, and the inner core ball corresponds to and abuts against the first support fence, so that the inner core ball is spaced apart from the first pad;

[0029] Form a plastic sealing layer between the first substrate and the second substrate, wherein the plastic sealing layer covers the package chip and the double-layer solder ball.

[0030] The beneficial effects of the embodiments of the present application include:

[0031] The embodiments of the present application provide a stacked package structure and a preparation method of the stacked package structure. The first pad and the second pad are arranged on the front surface of the first substrate, and the first pad is arranged around the second pad. The first support fence is further arranged on the first pad. The package chip is attached to the first substrate. The third pad is arranged on the back surface of the second substrate, and the third pad corresponds to the first pad. The double-layer solder ball is arranged on the back surface of the second substrate. The outer solder layer of the double-layer solder ball covers the first support fence, and the inner core ball corresponds to and supports the first support fence, so that the inner core ball is spaced apart from the first pad.

[0032] Compared with the prior art, the double-layer solder ball is used in the embodiments of the present application, and the first support fence is additionally arranged on the first pad. The first support fence is embedded in the outer solder layer, which greatly improves the bonding strength of the outer solder layer and the first pad, thereby effectively improving the welding strength and reducing the risk of bridging or virtual welding caused by substrate warping. In addition, the tin amount of the outer solder layer is uniformly distributed and will not overflow too much to cause bridging. At the same time, due to the supporting effect of the first support fence, the inner core ball can be supported, which effectively slows down the solder ball collapse phenomenon, thereby ensuring that the gap between the first substrate and the second substrate meets the plastic sealing requirement, increasing the plastic sealing space and slowing down the plastic sealing cavity phenomenon. The first support fence can also limit the inner core ball to prevent the inner core ball from deviating during welding, thereby ensuring the welding reliability. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 The schematic diagram of the stacked package structure provided by the first embodiment of the present application;

[0035] Figure 2 The Figure 1 The local enlarged schematic diagram of II in the middle;

[0036] Figure 3 The schematic diagram of another stacked package structure provided by the first embodiment of the present application;

[0037] Figure 4This is a schematic diagram of the structure corresponding to step S1 in the method for preparing the stacked packaging structure provided in the first embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the structure corresponding to step S2 in the method for preparing the stacked packaging structure provided in the first embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the structure corresponding to step S3 in the method for preparing the stacked packaging structure provided in the first embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram of the structure corresponding to step S4 in the method for preparing the stacked packaging structure provided in the first embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the structure corresponding to step S5 in the method for preparing the stacked packaging structure provided in the first embodiment of the present invention.

[0042] Figure 9 This is a schematic diagram of the stacked packaging structure provided in the second embodiment of the present invention;

[0043] Figure 10 for Figure 9 A magnified view of a portion of point X in the middle;

[0044] Figure 11 This is a partial structural diagram of the first stacked packaging structure provided in the third embodiment of the present invention;

[0045] Figure 12 This is a partial structural diagram of the second stacked packaging structure provided in the third embodiment of the present invention;

[0046] Figure 13 This is a partial structural diagram of the third stacked packaging structure provided in the third embodiment of the present invention;

[0047] Figure 14 This is a partial structural diagram of the first stacked packaging structure provided in the fourth embodiment of the present invention;

[0048] Figure 15 This is a partial structural diagram of the second stacked packaging structure provided in the fourth embodiment of the present invention;

[0049] Figure 16 This is a partial structural diagram of the third stacked packaging structure provided in the fourth embodiment of the present invention;

[0050] Figure 17 This is a partial structural diagram of the stacked packaging structure provided in the fifth embodiment of the present invention.

[0051] Icons: 100 - Stacked package structure; 110 - First substrate; 111 - First pad; 112 - Second pad; 113 - First solder mask; 114 - First solder opening; 120 - Packaged chip; 130 - Second substrate; 131 - Third pad; 132 - Second solder mask; 133 - Second solder opening; 140 - Double-layer solder ball; 141 - Core ball; 142 - Outer solder layer; 150 - Molding layer; 160 - First support enclosure; 161 - First groove; 162 - First stepped groove; 170 - Packaged device; 180 - Support conductive post; 190 - Second support enclosure; 191 - Second groove; 192 - Second stepped groove. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0053] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0054] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0055] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0056] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0057] As disclosed in the background section, existing POP stack structures typically use copper core solder balls for interconnecting the substrate pads. However, current copper core solder ball solutions have the following problems:

[0058] 1. Due to the different materials used in different layers of the package, the thermal expansion coefficients between the materials are different, which makes the substrate / interface board prone to warping during reflow soldering, resulting in bridging or cold solder joints between solder balls.

[0059] 2. In traditional POP packages, an adapter board structure is usually used for soldering. Solder balls need to be formed on the adapter board and then soldered to pads on the substrate surface. Since the substrate is prone to warping, bridging can easily occur between the solder balls.

[0060] 3. In traditional structures, the opening width of the solder pads on the substrate is relatively large, which is usually larger than the diameter of the copper core ball. This causes the solder ball to melt and collapse during the soldering process, resulting in a reduced support height. This leads to an excessively small substrate spacing, a small molding space, and difficulty in filling the molding compound during molding, which can easily result in voids.

[0061] 4. In traditional structures, the solder joints generate high temperatures and electromigration during the operation of the entire product, which can easily cause the solder balls to remelt, thus posing the same risks of bridging and desoldering.

[0062] 5. In traditional structures, the copper core ball has no support or restraint during the welding process. After the outer layer of tin melts, the inner copper core ball is prone to displacement, affecting welding accuracy and conductivity.

[0063] To address the aforementioned problems, embodiments of the present invention provide a novel stacked packaging structure and a method for preparing the stacked packaging structure. It should be noted that, unless otherwise specified, the features in the embodiments of the present invention can be combined with each other.

[0064] First Embodiment

[0065] See Figure 1 and Figure 2 The present invention provides a stacked packaging structure 100, which can effectively improve welding strength, reduce the risk of bridging or poor soldering, and effectively increase the plastic packaging space to alleviate the phenomenon of plastic packaging voids.

[0066] The stacked packaging structure 100 provided in this embodiment of the invention includes a first substrate 110, a packaged chip 120, a second substrate 130, double-layer solder balls 140, and a molding compound 150. The first substrate 110 has a first pad 111 and a second pad 112 on its front side, with the first pad 111 surrounding the second pad 112. A first support fence 160 is also provided on the first pad 111. The packaged chip 120 is mounted on the first substrate 110 and electrically connected to the second pad 112. The second substrate 130 is located on the side of the packaged chip 120 away from the first substrate, and a third pad 131 is provided on the back side of the second substrate 130, corresponding to the first pad 111. The double-layer solder balls 140 are located on the back side of the second substrate 130. The double-layer solder balls 140 include a core ball 141 and an outer solder layer 142. The outer solder layer 142 covers the core ball 141 and is simultaneously connected to the third pad 131 and the first pad 111. The outer solder layer 142 also covers the first support fence 160, and the core ball 141 is correspondingly held against the first support fence 160, so that the core ball 141 is spaced apart from the first pad 111. A molding compound 150 is formed between the first substrate 110 and the second substrate 130 and covers the packaged chip 120 and the double-layer solder balls 140.

[0067] It should be noted that both the first substrate 110 and the second substrate 130 can be coreless or cored substrates. Preferably, both the first substrate 110 and the second substrate 130 are coreless substrates, which can reduce the stacking thickness. The first substrate 110 and the second substrate 130 can be composed of epoxy fiberglass boards, Ajinomoto multilayer films, etc., and their basic structure and internal wiring methods can refer to existing substrates or adapter boards. Furthermore, in this embodiment of the invention, the "front side" refers to the upper surface in the illustrated direction, while the "back side" refers to the lower surface in the illustrated direction.

[0068] It is worth noting that in this embodiment, the double-layer solder ball 140 has a core ball 141 that is a metal ball with a melting point higher than that of the outer solder layer. For example, the material of the core ball 141 can be at least one of copper, gold, and silver, and its diameter can be between 100μm and 200μm, such as 180μm. Meanwhile, the outer solder layer 142 is also a metal layer with a melting point lower than that of the core ball. For example, it can be a tin layer, tin-silver layer, tin-silver-copper layer, tin-silver-bismuth layer, or tin-silver-nickel layer, etc., and its outer diameter can be between 200-300μm, such as 220μm. It should be noted that the dimensions of the core ball 141 and the outer solder layer 142 described here are merely illustrative and do not constitute any limitation; they can be adjusted according to the actual package size.

[0069] In this embodiment, a first solder resist layer 113 is further provided on the front side of the first substrate 110. The first solder resist layer 113 covers the first pad 111 and forms a first soldering opening 114 that partially exposes the first pad 111. A first support fence 160 is disposed on the first pad 111 in the first soldering opening 114. An outer solder layer 142 fills the first soldering opening 114 and contacts the first pad 111 in the first soldering opening 114. Specifically, the first solder resist layer 113 can be a green paint layer, which can play a solder resisting role. The first solder resist layer 113 can cover the edge area of ​​the first pad 111, so that the first soldering opening 114 exposes the middle area of ​​the first pad 111. The outer solder layer 142 can completely fill the first soldering opening 114 and cover both the inner and outer sides of the first support fence 160. Meanwhile, the first solder mask layer 113 can also expose the second pad 112, thereby facilitating the flip-chip 120 to be soldered onto the second pad 112 and realizing the electrical connection between it and the first substrate 110.

[0070] It should be noted that the first support fence 160 here can be a metal fence, such as at least one of copper, tungsten, and titanium. When the first support fence 160 is made of copper or tungsten, the heat dissipation effect of the welded structure can be greatly improved, thereby avoiding bridging caused by excessive melting at high temperatures during operation. The first support fence 160 can be composed of multiple copper columns of the same height, and the gaps between the multiple copper columns can allow solder to flow, thereby ensuring the filling effect of the outer weld layer 142.

[0071] In this embodiment, the first support fence 160 is distributed along a circumference, and the inner diameter of the first support fence 160 is smaller than the outer diameter of the core ball 141, so that the core ball 141 is supported by the first support fence 160. Specifically, the inner diameter of the first support fence 160 refers to the inner diameter of the circumference of the distribution of the first support fence 160. The outer diameter of the core ball 141 is larger than the opening width of the first support fence 160, thereby ensuring that the core ball 141 can be supported on the top of the first support fence 160 after welding. The first support fence 160 plays a supporting role for the core ball 141, thereby effectively raising the height of the core ball 141 and ensuring that there is a gap between the core ball 141 and the first solder pad 111, which is filled by the outer solder layer 142. Because the first support fence 160 lifts the core ball 141, it prevents the core ball 141 from collapsing and further lifts the second substrate 130, increasing the distance between the second substrate 130 and the first substrate 110. This provides sufficient space for the molding compound during molding, reducing the risk of voids in the molding compound. The first support fence 160 also limits the position of the core ball 141, preventing it from shifting during welding and ensuring the horizontal consistency and uniformity of the multiple core balls 141, thereby guaranteeing welding reliability.

[0072] Of course, in other preferred embodiments of the present invention, the first support fence 160 may also be distributed in a rectangular pattern, and its opening width is smaller than the outer diameter of the core ball 141, which can also play a supporting role for the core ball 141.

[0073] In this embodiment, the outer diameter of the first support fence 160 is smaller than the width of the first welding opening 114, so that the edges of the first support fence 160 and the first welding opening 114 are spaced apart. Specifically, there is a certain gap W between the sidewall of the first support fence 160 and the first welding opening 114. This gap W can be between 20μm and 200μm and can be filled with molding compound, thereby further improving the bonding force between the outer weld layer 142 and the first support fence 160.

[0074] In this embodiment, the packaged chip 120 can be flip-chip soldered onto the second pad 112, and an underfill adhesive layer can be formed on the bottom of the packaged chip 120 to protect the soldered structure. Furthermore, there can be a certain gap between the packaged chip 120 and the back surface of the second substrate 130, which is filled with molding compound to prevent contact between the second substrate 130 and the packaged chip 120, thus preventing interference from the packaged chip 120 in the mounting of the second substrate 130.

[0075] In this embodiment, solder balls are also provided on the side of the first substrate 110 away from the second substrate 130, and solder balls can be formed on the back side of the first substrate 110 by a ball-planting process.

[0076] In this embodiment, a second solder resist layer 132 is also provided on the back side of the second substrate 130. The second solder resist layer 132 covers the third pad 131 and forms a second solder opening 133 that partially exposes the third pad 131. The outer solder layer 142 fills the second solder opening 133 and contacts the third pad 131 in the second solder opening 133.

[0077] See Figure 3 Furthermore, the stacked packaging structure 100 may also include a packaging device 170, which is mounted on the front side of the second substrate 130, that is, the packaging device 170 is mounted on the side of the second substrate 130 away from the first substrate 110 and is electrically connected to the second substrate 130. The packaging device 170 may be a module chip or a memory chip, etc.

[0078] This invention also provides a method for fabricating a stacked packaging structure 100, which includes the following steps:

[0079] S1: Provide a first substrate 110.

[0080] See alsoFigure 4 The first substrate 110 has a first pad 111 and a second pad 112 on its front side, with the first pad 111 surrounding the second pad 112. Specifically, the first substrate 110 can be a coreless substrate or a cored substrate; preferably, it is a coreless substrate to reduce the stacking height. The first substrate 110 can be composed of epoxy fiberglass board, Ajinomoto multilayer film, etc. The front side of the first substrate 110 also has a first solder resist layer 113, which is a green paint layer, and forms a first solder opening 114 exposing the first pad 111. Naturally, the first solder resist layer 113 also exposes the second pad 112.

[0081] S2: Form a first support fence 160 on the first pad 111.

[0082] See Figure 5 Specifically, a metal layer is first formed on the front side of the first substrate 110 using an electroplating or metal sputtering process. This metal layer can be a copper layer, a tungsten layer, or a titanium layer. When a copper or tungsten layer is used, the heat dissipation effect of the solder structure can be significantly improved, avoiding bridging problems caused by excessive melting of solder during operation. After forming the metal layer, an etching process can be used again to cover the areas that need to be retained with a protective film. Then, plasma or chemical etching is used to remove the excess metal layer, thereby forming a copper pillar structure, which forms the first support fence 160.

[0083] S3: Mount the packaged chip 120 onto the first substrate 110.

[0084] See Figure 6 The packaged chip 120 is electrically connected to the second pad 112. Specifically, the packaged chip 120 can be flip-chip soldered onto the second pad 112, and then an underfill adhesive layer is formed using a dispensing process to protect the bottom of the packaged chip 120 before baking and curing.

[0085] S4: The second substrate 130, on which double-layer solder balls 140 are formed on the back, is mounted on the first substrate 110.

[0086] See Figure 7 The back side of the second substrate 130 is provided with a third pad 131, which corresponds to the first pad 111. The double-layer solder ball 140 includes a core ball 141 and an outer solder layer 142. The outer solder layer 142 covers the core ball 141 and is connected to both the third pad 131 and the first pad 111. The outer solder layer 142 covers the first support fence 160, and the core ball 141 is correspondingly held against the first support fence 160 so that the core ball 141 is spaced apart from the first pad 111.

[0087] Specifically, the second substrate 130 can be prepared in advance, that is, a double layer of solder balls 140 is formed on the back side of the second substrate 130 by ball-planting, and then the double layer of solder balls 140 is correspondingly soldered onto the first pad 111 to realize the mounting of the second substrate 130. Specifically, the solder balls can be soldered by a thermoforming process, so that the outer solder layer 142 is fused and soldered onto the first pad 111, and the outer solder layer 142 can cover the first support fence 160, thereby improving the soldering strength.

[0088] S5: A molding layer 150 is formed between the first substrate 110 and the second substrate 130.

[0089] See Figure 8 The molding compound 150 covers the packaged chip 120 and the double-layer solder balls 140. Specifically, a molding compound can be filled between the first substrate 110 and the second substrate 130 using a molding process, and the molding compound 150 is formed after curing. Since the core ball 141 of the double-layer solder balls 140 is supported by the first support fence 160, the space between the first substrate 110 and the second substrate 130 is increased, effectively reducing the phenomenon of molding voids.

[0090] After forming the molding compound 150, solder balls can be formed on the back side of the first substrate 110 using a ball-mounting process. Here, the solder balls are single-layer solder balls. Finally, a dicing process is used to form individual products.

[0091] It is worth noting that after the ball is placed, a packaging device 170 can also be mounted on the front side of the second substrate 130. The packaging device 170 can be a module chip or a memory chip.

[0092] In summary, this invention provides a stacked package structure 100 and a method for fabricating the stacked package structure 100. A first pad 111 and a second pad 112 are disposed on the front side of a first substrate 110, with the first pad 111 surrounding the second pad 112. A first support fence 160 is also disposed on the first pad 111. A packaged chip 120 is mounted on the first substrate 110. A third pad 131 is disposed on the back side of a second substrate 130, corresponding to the first pad 111. A double-layer solder ball 140 is located on the back side of the second substrate 130, with the outer solder layer 142 of the double-layer solder ball 140 covering the first support fence 160, and the core ball 141 correspondingly abutting against the first support fence 160, such that the core ball 141 is spaced apart from the first pad 111. Compared to existing technologies, this embodiment of the invention employs a double-layer solder ball 140 and adds a first support fence 160 to the first pad 111. The first support fence 160 is embedded in the outer solder layer 142, significantly improving the bonding strength between the outer solder layer 142 and the first pad 111. This effectively enhances the soldering strength and reduces the risk of bridging or cold solder joints caused by substrate warping. Furthermore, the solder distribution in the outer solder layer 142 is uniform, preventing excessive overflow that could lead to bridging. Simultaneously, the support provided by the first support fence 160 supports the core ball 141, effectively mitigating solder ball collapse. This ensures that the gap between the first substrate 110 and the second substrate 130 meets the molding requirements, increasing the molding space and reducing the likelihood of voids in the molding process.

[0093] Second Embodiment

[0094] See Figure 9 and Figure 10 This embodiment of the invention provides a stacked packaging structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment.

[0095] In this embodiment, the third pad 131 in the second soldering opening 133 is further provided with a supporting conductive post 180 protruding towards the second substrate 130, and the supporting conductive post 180 is connected to the core ball 141. Specifically, the supporting conductive post 180 can be a copper post, located at the center of the third pad 131 and connected to the top of the core ball 141. By providing the supporting conductive post 180, the top of the core ball 141 can be supported during hot-press soldering, effectively preventing the core ball 141 from directly contacting the third pad 131, further preventing the collapse of the double-layer solder ball 140, thereby further increasing the gap width between the first substrate 110 and the second substrate 130, and controlling the amount of solder overflow. Furthermore, the supporting conductive post 180 contacts the core ball 141, while the core ball 141 contacts the first supporting fence 160. Both the supporting conductive post 180 and the first supporting fence 160 adopt a copper post structure, which can improve the conductivity of the overall soldering structure.

[0096] In this embodiment, the center of the supporting conductive post 180 corresponds to that of the first supporting fence 160, so that the supporting conductive post 180 and the first supporting fence 160 are staggered. Specifically, the staggered arrangement of the supporting conductive post 180 and the first supporting fence 160 means that the projection of the supporting conductive post 180 on the first pad 111 is spaced apart from that of the first supporting fence 160, thereby making the force on the core ball 141 more uniform.

[0097] The stacked packaging structure 100 provided in this embodiment of the invention realizes the upper and lower double copper pillar structure of the core ball 141 by setting the supporting conductive pillar 180. During hot pressing welding, after the outer solder layer 142 melts, it can use the supporting conductive pillar 180 to squeeze the core ball 141, so that the core ball 141 can fully contact the first supporting fence 160, thereby greatly improving the conductivity.

[0098] Third Embodiment

[0099] See Figure 11 to Figure 13 This embodiment of the invention provides a stacked packaging structure 100, whose basic structure, principle, and resulting technical effects are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment. Compared with the first embodiment, the setting position and structure of the first support fence 160 are different in this embodiment.

[0100] See Figure 11In this embodiment, the first support fence 160 is distributed along the edge of the first welding opening 114 and partially covers the periphery of the first welding opening 114. Specifically, the first support fence 160 fills the edge area of ​​the first welding opening 114 and can cover the periphery of the first welding opening 114, thereby covering the sidewall of the first welding opening 114 and reducing the manufacturing difficulty of the first support fence 160. Furthermore, since the first support fence 160 partially covers the edge area of ​​the first welding opening 114, the first solder resist layer 113 can play a structural support role, thereby preventing the core ball 141 from bending the first support fence 160 during hot-press welding. In addition, a step can be formed between the sidewall of the first support fence 160 and the top surface of the first solder resist layer 113, thereby further increasing the contact area between the outer solder layer 142 and the first support fence 160, thereby improving the wettability of the outer solder layer 142 and the bonding force, effectively avoiding the problem of thermal stress microcracks in traditional tin layers and green paint layers.

[0101] See Figure 12 Furthermore, a first groove 161 is provided in the middle of the end face of the first support fence 160, and the outer weld layer 142 fills the first groove 161. Specifically, the first groove 161 does not penetrate to the surface of the first solder resist layer 113, but is located in the middle of the top side surface of the first support fence 160. By providing the first groove 161, the bonding force between the outer weld layer 142 and the first support fence 160 can be further improved, thereby further improving the welding strength and preventing incomplete welding or detachment. In addition, the first groove 161 can improve the sidewall bonding force and act as a buffer structure to absorb stress and avoid stress concentration.

[0102] It should be noted that the first groove 161 here can also serve to accommodate the outer solder layer 142. The outer solder layer 142 fills the first groove 161, so that the outer solder layer 142 has enough space to accommodate it, which can effectively prevent the solder of the outer solder layer 142 from overflowing excessively and causing bridging.

[0103] See Figure 13 In other preferred embodiments of the present invention, a first stepped groove 162 is provided on the edge of the first support fence 160, and the first stepped groove 162 extends to the outer side wall of the first support fence 160, so that the outer edge of the first support fence 160 forms a first stepped structure. Specifically, the first stepped groove 162 is a notch design, which forms a first stepped structure, which can further improve the wettability of the tin layer and improve the bonding force, avoiding the problem of thermal stress microcracks in the traditional tin layer and green paint layer.

[0104] Fourth embodiment

[0105] See Figure 14 to Figure 16This embodiment of the invention provides a stacked packaging structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment.

[0106] See Figure 14 In this embodiment, the first support fence 160 is distributed along the edge of the first welding opening 114 and partially covers the periphery of the first welding opening 114. Further, a first groove 161 is provided in the middle of the end face of the first support fence 160, and the outer solder layer 142 fills the first groove 161. A second solder resist layer 132 is also provided on the back side of the second substrate 130. The second solder resist layer 132 covers the third pad 131 and forms a second welding opening 133 that partially exposes the third pad 131. The outer solder layer 142 fills the second welding opening 133 and contacts the third pad 131 in the second welding opening 133. Further, a second support fence 190 is also provided on the third pad 131. The second support fence 190 is distributed along the edge of the second welding opening 133 and partially covers the periphery of the second welding opening 133. A second groove 191 is provided in the middle of the end face of the second support fence 190, and the outer solder layer 142 fills the second groove 191. The second support fence 190, by providing a second groove 191, can further enhance the bonding force between the outer solder layer 142 and the second support fence 190. Furthermore, both the second groove 191 and the first groove 161 can accommodate the solder of the outer solder layer 142, thus effectively preventing excessive solder overflow and bridging. The arrangement and technical effect of the second groove 191 can be referenced from that of the first groove 161.

[0107] Furthermore, the groove width and groove depth of the first groove 161 can be the same as the groove width and groove depth of the second groove 191, so that the first groove 161 and the second groove 191 have the same capacity to accommodate solder, so that the solder overflowing during the soldering process can be evenly filled into the first groove 161 and the second groove 191, avoiding excessive solder overflow that could lead to bridging risk.

[0108] See Figure 15 In other preferred embodiments of the present invention, a second stepped groove 192 is provided on the edge of the second support fence 190, and the second stepped groove 192 extends to the outer side wall of the second support fence 190, so that the outer edge of the second support fence 190 forms a second stepped structure. At this time, a first groove 161 can be provided on the first support fence 160. Through the combination of the first groove 161 and the second stepped groove 192, the bonding force of the outer weld layer 142 can be further improved.

[0109] See Figure 16In other preferred embodiments of the present invention, a second stepped groove 192 is provided on the edge of the second support fence 190, and the second stepped groove 192 extends to the outer wall of the second support fence 190, so that the outer edge of the second support fence 190 forms a second stepped structure. At this time, a first stepped groove 162 can also be provided on the first support fence 160. Through the combination of the second stepped groove 192 and the first stepped groove 162, the solder in the outer solder layer 142 can be further accommodated, effectively mitigating the bridging phenomenon caused by solder overflow.

[0110] It should be noted that the groove structures on the first support fence 160 and the second support fence 190 can be combined and transformed with each other, and will not be listed here. In this embodiment, by adopting a double-sided groove structure, the welding strength of the outer weld layer 142 can be greatly improved, the reliability of the drop test can be improved, and the contact area of ​​the solder can be increased, thereby improving conductivity.

[0111] Fifth Embodiment

[0112] See Figure 17 This embodiment of the invention provides a stacked packaging structure 100, whose basic structure, principle and technical effects are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment.

[0113] In this embodiment, the first support fence 160 is distributed along the edge of the first welding opening 114 and partially covers the periphery of the first welding opening 114. A second solder resist layer 132 is also provided on the back side of the second substrate 130. The second solder resist layer 132 covers the third pad 131 and forms a second welding opening 133 that partially exposes the third pad 131. An outer solder layer 142 fills the second welding opening 133 and contacts the third pad 131 within the second welding opening 133. Furthermore, the third pad 131 is also provided with a second support fence 190, which is distributed along the edge of the second welding opening 133 and partially covers the periphery of the second welding opening 133.

[0114] In this embodiment, the end face of the first support fence 160 is also provided with a first groove 161. At the same time, in this embodiment of the invention, the outer diameter of the first support fence 160 is larger than the outer diameter of the outer welding layer 142, that is, the width of the end face of the first support fence 160 is larger. In actual welding, the outer side wall of the first support fence 160 can be exposed to the outer welding layer 142 and covered by the plastic sealing layer 150.

[0115] Furthermore, the outer weld layer 142 can partially fill the first groove 161, thereby exposing the edge of the first support fence 160 to the outer weld layer 142. While ensuring the welding strength, the edge of the first support fence 160 can contact the molding compound 150, thereby improving the bonding strength between the molding compound 150 and the first solder pad 111 and further mitigating the warping phenomenon.

[0116] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A stacked package structure, characterized by, The application relates to a packaging structure of a chip, which comprises the following parts: a first substrate, the front surface of which is provided with a first pad and a second pad, the first pad is arranged around the second pad, and a first support fence is arranged on the first pad; a packaging chip, which is attached to the first substrate and is electrically connected with the second pad; a second substrate, which is arranged on the side of the packaging chip away from the first substrate, and the back surface of the second substrate is provided with a third pad, which corresponds to the first pad respectively; a double-layer solder ball, which is arranged on the back surface of the second substrate, the double-layer solder ball comprises a core ball and an outer solder layer, the outer solder layer covers the core ball and is connected with the third pad and the first pad at the same time, the outer solder layer covers the first support fence, the core ball corresponds to the first support fence and is spaced from the first pad; and a plastic sealing layer, which is formed between the first substrate and the second substrate and covers the packaging chip and the double-layer solder ball. The front surface of the first substrate is further provided with a first resist layer, the first resist layer covers the first pad and forms a first welding opening which partially exposes the first pad, the first support fence is arranged on the first pad in the first welding opening, and the outer solder layer is filled in the first welding opening and is in contact with the first pad in the first welding opening. The first support fence is distributed along a circumference, and the inner diameter of the first support fence is smaller than the outer diameter of the core ball, so that the core ball is supported by the first support fence. The outer diameter of the first support fence is smaller than the width of the first welding opening, so that the first support fence is arranged in a spaced manner with the edge of the first welding opening. The first support fence is distributed along the edge of the first welding opening and partially covers the circumference of the first welding opening. The middle part of the end surface of the first support fence is provided with a first groove, and the outer solder layer is filled in the first groove.

2. The stacked package structure of claim 1, wherein, The edge of the first support fence is provided with a first stepped groove which extends to the outer sidewall of the first support fence, so that the outer edge of the first support fence forms a first stepped structure.

3. The stacked package structure of claim 2, wherein, The back surface of the second substrate is further provided with a second resist layer, the second resist layer covers the third pad and forms a second welding opening which partially exposes the third pad, and the outer solder layer is filled in the second welding opening and is in contact with the third pad in the second welding opening.

4. The stacked package structure of claim 3, wherein, The third pad is further provided with a second support fence, the second support fence is distributed along the edge of the second welding opening and partially covers the circumference of the second welding opening.

5. The stacked package structure of claim 2, wherein, The middle part of the end surface of the second support fence is provided with a second groove, and the outer solder layer is filled in the second groove; or 6. The stacked package structure of claim 5, wherein, The edge of the second support fence is provided with a second stepped groove which extends to the outer sidewall of the second support fence, so that the outer edge of the second support fence forms a second stepped structure.

7. The stacked package structure of claim 5, wherein, The third pad in the second welding opening is further provided with a support conductive column which protrudes towards the second substrate, and the support conductive column is connected with the core ball.

8. The stacked package structure of any one of claims 2-7, wherein, ​ 9. The stacked package structure of claim 8, wherein, ​ 10. The stacked package structure of claim 9, wherein, ​ ​ 11. The stacked package structure of claim 8, wherein, ​ 12. The stacked package structure of claim 11, wherein, The support conductive column corresponds to the center of the first support fence, so that the support conductive column is arranged in a staggered manner with the first support fence.

13. The stacked package structure of claim 1, wherein, The stacked package structure further comprises a package device attached to the front surface of the second substrate.

14. A method for manufacturing a stacked package structure according to claim 1, wherein The preparation method comprises: providing a first substrate, wherein a first pad and a second pad are arranged on the front surface of the first substrate, and the first pad is arranged around the second pad; forming a first support fence on the first pad; attaching a package chip to the first substrate, wherein the package chip is electrically connected to the second pad; attaching a second substrate with a double-layer solder ball formed on the back surface to the first substrate, wherein a third pad is arranged on the back surface of the second substrate, and the third pad corresponds to the first pad respectively, the double-layer solder ball comprises a core ball and an outer solder layer, the outer solder layer is coated on the core ball and is connected to the third pad and the first pad at the same time, and the outer solder layer is coated on the first support fence, and the core ball corresponds to and abuts against the first support fence, so that the core ball is spaced apart from the first pad; forming a plastic encapsulation layer between the first substrate and the second substrate, wherein the plastic encapsulation layer is coated on the package chip and the double-layer solder ball.

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