A fan-out package with a three-dimensional electromagnetic shielding structure and a method of manufacturing the same

Abstract

This invention discloses a fan-out package with a three-dimensional electromagnetic shielding structure and its fabrication method. The fan-out package includes a molding compound covering a central metal sheet; a first chip and a second chip are respectively disposed above and below the central metal sheet; at least two rows of inner copper pillars and at least two rows of outer copper pillars penetrate the molding compound; a first superwiring layer is disposed on the metal bumps of the first chip and the outer copper pillars, and a first insulating layer is coated on the first superwiring layer, forming a first continuous shielding layer on the surface of the first insulating layer; a second superwiring layer is disposed on the metal bumps of the second chip and the outer copper pillars, forming a back pad; the bottom of the inner copper pillars is led out to the surface through the second superwiring layer, forming an independent ground pad; solder balls are disposed on the back pad and the ground pad; this invention can simultaneously construct a three-dimensional, continuous electromagnetic shielding structure in the fan-out packaging process, achieving all-round shielding of stacked chips, while maintaining the miniaturization and high integration of the package.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip packaging technology, specifically to a fan-out package with a three-dimensional electromagnetic shielding structure and its preparation method. Background Technology

[0002] As electronic products evolve towards miniaturization, multifunctionality, and high-frequency, high-speed operation, system-in-package (SiP) and fan-out packaging technologies are widely used. These technologies often require integrating multiple chips (such as processors, memory, and RF chips) into a single package. However, these chips with different functions generate electromagnetic interference (EMI) during operation, severely impacting the stability and reliability of the system performance.

[0003] Existing electromagnetic shielding solutions typically have the following limitations:

[0004] Post-mount shielding: An additional metal shielding cover is mounted after packaging. This method only covers the top and part of the sides of the package and cannot effectively isolate electromagnetic interference inside the package, especially between chips. It also increases the number of process steps and the package thickness.

[0005] Conductive adhesive / spraying: Applying conductive paint or conductive adhesive to the surface of the encapsulated material. This method also only achieves external shielding, and its shielding effectiveness is limited, with issues regarding adhesion and reliability.

[0006] Integrated shielding walls: Through-hole shielding is fabricated within the packaging substrate. This method is mainly suitable for chips with a two-dimensional planar layout. For vertically stacked multi-chip structures, it is difficult to achieve independent and continuous shielding of the sides and back of each chip layer.

[0007] Therefore, there is an urgent need in the field for a solution that can provide all-round (top, bottom, and side) high-performance electromagnetic shielding for stacked chips, while maintaining high process integration and not affecting package miniaturization. Summary of the Invention

[0008] In view of the technical problems existing in the background art, the present invention provides a fan-out package with a three-dimensional electromagnetic shielding structure that can provide omnidirectional (top, bottom, and side) high-performance electromagnetic shielding for stacked chips, and has high process integration and does not affect the miniaturization of the package, as well as a method for fabricating the same. To achieve the above objectives, the present invention provides the following technical solution:

[0009] A fan-out type package with a three-dimensional electromagnetic shielding structure, characterized in that it comprises:

[0010] A central metal plate divides the internal space of the package into upper and lower chambers.

[0011] The first chip and the second chip are located on the upper and lower sides of the central metal sheet.

[0012] A plastic encapsulation that covers the chip and the central metal plate.

[0013] The inner and outer rows of copper pillars penetrate the plastic seal.

[0014] The first routing layer (first RDL) and the first continuous shielding layer are located on the front side of the molding compound.

[0015] The second routing layer (second RDL) and solder balls are located on the back of the molding compound.

[0016] Three-dimensional shielding structure: The central metal sheet, the inner row of copper pillars, the first continuous shielding layer on the front and the grounding pads led out from the second RDL on the back together form a Faraday cage-like closed shielding cavity, which isolates the first chip and the second chip respectively.

[0017] A method for fabricating a fan-out type package with a three-dimensional electromagnetic shielding structure includes the following steps:

[0018] Provide a pre-placed metal sheet and temporary bonding: Prepare a metal sheet (such as a copper sheet) with pre-drilled holes; attach the metal sheet to the temporary carrier board using temporary bonding adhesive.

[0019] First chip mounting and encapsulation: The first chip is mounted onto the metal sheet with its back side using mounting adhesive or mounting film, and the front side of the first chip has a first metal bump; then the first overall encapsulation is performed to form a first encapsulation body, which covers the front and sides of the first chip and the metal sheet.

[0020] Carrier removal and second chip mounting: Remove the temporary carrier to expose the back of the metal sheet; mount the second chip to the back of the metal sheet with its back side using mounting adhesive or mounting film, and the front side of the second chip has a second metal bump; then perform a second overall molding to form a second molded body, covering the back of the second chip and the metal sheet.

[0021] Forming a shielded through-hole array: Drilling holes in the composite molding compound to form at least two rows of through-hole arrays:

[0022] Internal through holes: Their positions are aligned with the pre-drilled holes on the metal sheet, and they are used to construct an electromagnetic shielding structure.

[0023] External vias: Located outside the internal vias, they are used to construct electrical channels for interconnecting the chip with the outside world.

[0024] Electroplating to form copper pillars: Metal is electroplated in the inner and outer through holes to form inner and outer copper pillars, respectively.

[0025] Thinning and bump exposure: Thin the front and back of the encapsulated body until the first and second metal bumps are exposed, and make the top of the bumps flush with the top of the copper pillar.

[0026] Front wiring and shielding layer lead-out:

[0027] A first redistribution layer (RDL) is fabricated on the front molding body to electrically interconnect the outer copper pillars with the first metal bump.

[0028] A first insulating layer (such as photoresist) is coated on the surface of the first RDL. The surface of the first RDL includes the RDL itself and the top of the inner copper pillars. The photoresist covers the area of ​​the first RDL except for the top of the inner copper pillars, thus achieving insulation from the outside world.

[0029] Key step: A first continuous shielding layer is formed on the surface of the first insulating layer by sputtering or deposition. This first continuous shielding layer is electrically connected to the top of all inner row copper pillars, thereby forming a complete shielding plane on the front of the package.

[0030] Backside wiring and solder ball preparation:

[0031] A second redistribution layer (RDL) is fabricated on the back molded body to electrically interconnect the outer copper pillars with the second metal bumps and form a back pad.

[0032] At the same time, the bottom of the inner row of copper pillars is led out to the surface of the second RDL on the back through the second RDL and formed an independent grounding pad for grounding after ball planting.

[0033] Balls are placed on the back pads and ground pads to form solder balls for interconnection with external circuit boards.

[0034] The beneficial effects of this invention are:

[0035] 1. Three-dimensional all-round shielding of the present invention: The present invention creatively constructs a complete three-dimensional shielding cavity consisting of a central metal plate (shielding ground plane), inner row of copper pillars (shielding side walls), a continuous shielding layer on the front (top cover) and a shielding lead-out on the back (bottom cover). This structure can simultaneously provide electromagnetic isolation to the top, bottom and sides of the stacked chips, and the shielding effectiveness is far superior to traditional single-sided or partial shielding solutions.

[0036] 2. High process integration and compact structure: The construction of the electromagnetic shielding structure is fully integrated into the standard fan-out packaging process (such as molding, drilling, electroplating, RDL, etc.), without the need for additional mounting or spraying steps. The central metal sheet not only serves as a shielding layer, but also plays a supporting and heat dissipation role in the structure, making the packaging structure thinner and more stable.

[0037] 3. Achieve vertical isolation between chips: The stacked chips are physically isolated in two independent chambers using a central metal plate. This not only shields against external interference, but also effectively suppresses electromagnetic interference between the upper and lower chips, solving the most challenging problem of crosstalk between chips in multi-chip stacking.

[0038] 4. Separation of power / signal and shielding grounding paths: By designing two independent rows of copper pillars, the physical separation of electrical interconnection (signal / power) and electromagnetic shielding (grounding) paths is achieved. The outer row of copper pillars is responsible for normal electrical signal transmission, while the inner row of copper pillars is dedicated to building a low-impedance shielding grounding network, avoiding mutual interference and improving signal integrity and shielding effect.

[0039] 5. Flexible shielding layer lead-out: By using an insulating layer and a sputtered shielding layer on the front and an RDL grounding pad on the back, a stable and reliable grounding path is provided for the entire three-dimensional shielding structure. Users can connect the shielding layer to the system grounding plate through the shielding solder balls on the back, which is easy to operate. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the fan-out package with a three-dimensional electromagnetic shielding structure according to the present invention;

[0041] Figure 2 This is a flowchart of the preparation method of the present invention;

[0042] Figure 3 This is a schematic diagram of the structure of the central metal sheet after step S1 of the present invention;

[0043] Figure 4 This is a schematic diagram of the fan-out package structure after step S2 of the present invention;

[0044] Figure 5 This is a schematic diagram of the fan-out package structure after step S3 of the present invention;

[0045] Figure 6 This is a schematic diagram of the fan-out package structure after step S4 of the present invention;

[0046] Figure 7 This is a schematic diagram of the fan-out package structure after step S5 of the present invention;

[0047] Figure 8 This is a schematic diagram of the fan-out package structure after step S6 of the present invention;

[0048] Figure 9 This is a schematic diagram of the fan-out package structure after step S7 of the present invention;

[0049] Figure 10 This is a schematic diagram of the fan-out package structure after step S8 of the present invention;

[0050] Figure 11 This is a schematic diagram of the fan-out package structure after step S9 of the present invention;

[0051] Figure 12 This is a schematic diagram of the structure of the fan-out type package after step S10 of the present invention;

[0052] Figure 13 This is a schematic diagram of the structure of the fan-out type package after step S11 of the present invention;

[0053] Figure 14 This is a schematic diagram of the front structure of the encapsulated body in this invention;

[0054] In the figure, 1-first continuous shielding layer, 2-first chip, 201-first metal bump, 3-second chip, 301-second metal bump, 4-second redistribution layer, 5-solder ball, 6-inner row of copper pillars, 7-central metal sheet, 701-pre-drilled hole, 8-outer row of copper pillars, 9-first redistribution layer, 10-molded body, 1001-inner row of through holes, 1002-outer row of through holes, 11-temporary carrier board. Detailed Implementation

[0055] Existing electromagnetic shielding solutions typically have the following limitations:

[0056] Post-mount shielding: An additional metal shielding cover is mounted after packaging. This method only covers the top and part of the sides of the package and cannot effectively isolate electromagnetic interference inside the package, especially between chips. It also increases the number of process steps and the package thickness.

[0057] Conductive adhesive / spraying: Applying conductive paint or conductive adhesive to the surface of the encapsulated material. This method also only achieves external shielding, and its shielding effectiveness is limited, with issues regarding adhesion and reliability.

[0058] Integrated shielding walls: Through-hole shielding is fabricated within the packaging substrate. This method is mainly suitable for chips with a two-dimensional planar layout. For vertically stacked multi-chip structures, it is difficult to achieve independent and continuous shielding of the sides and back of each chip layer.

[0059] To address the aforementioned technical problems, this invention proposes a fan-out type package with a three-dimensional electromagnetic shielding structure and its preparation method.

[0060] Combination Figures 1-14 A fan-out type package with a three-dimensional electromagnetic shielding structure includes a plastic encapsulation 10 covering a central metal sheet 7;

[0061] The central metal sheet 7 divides the internal space of the encapsulated body 10 into an upper chamber and a lower chamber. The edge of the central metal sheet 7 is evenly provided with a number of pre-drilled holes 701 that can be arranged into a rectangle.

[0062] The upper chamber contains a first chip 2, and the lower chamber contains a second chip 3;

[0063] The molding body 10 has at least two rows of inner through holes 1001 corresponding to the pre-drilled holes 701 of the central metal sheet 7, and the corresponding pre-drilled holes 701 and inner through holes 1001 are provided with inner copper pillars 6 penetrating the molding body 10.

[0064] The molding compound 10 has at least two rows of external through holes 1002 extending through its upper and lower ends and outside the inner through holes 1001. Each external through hole 1002 contains an external copper post 8 penetrating the molding compound 10. The external copper posts 8 are responsible for normal electrical signal transmission, while the inner copper posts 6 are dedicated to constructing a low-impedance shielded grounding network, avoiding mutual interference and improving signal integrity and shielding effectiveness. Preferably, as follows... Figure 14 As shown, the inner through holes 1001 and the outer through holes 1002 are arranged in a rectangular shape.

[0065] The first metal bump 201 of the first chip 2 and the outer copper pillar 8 are provided with a first rewiring layer 9. The first rewiring layer 9 is coated with a first insulating layer. A first continuous shielding layer 1 is formed on the surface of the first insulating layer. The first continuous shielding layer 1 is electrically connected to the top of all the inner copper pillars 6. The front of the encapsulation body 10 forms a complete shielding plane.

[0066] The second metal bump 301 and the outer copper pillar 8 of the second chip 3 are provided with a second red wiring layer 4 to form a back pad;

[0067] The bottom of the inner row of copper pillars 6 is led out to the surface of the second wiring layer 4 through the second wiring layer 4 to form a grounding pad;

[0068] Solder balls 5 for interconnection with external circuit boards are provided on the back pad and the ground pad;

[0069] The central metal plate 7 (shielding ground plane), the inner row of copper pillars 6 (shielding sidewalls), the first continuous shielding layer 1 on the front (top cover), and the grounding pad (bottom cover) led out from the second wiring layer 4 on the back together constitute a Faraday cage-like closed shielding cavity that can isolate the first chip 2 and the second chip 3. This structure can simultaneously provide electromagnetic isolation to the top, bottom, and sides of the stacked chips.

[0070] Preferably, the central metal sheet 7 is made of copper.

[0071] Preferably, the first continuous shielding layer 1 is made of photoresist.

[0072] A method for manufacturing a fan-out type package with a three-dimensional electromagnetic shielding structure, comprising the following steps:

[0073] S1, as Figure 3 As shown, several pre-drilled holes 701 that can be arranged into a rectangle are evenly provided near the edge of the central metal sheet 7;

[0074] S2, as Figure 4 As shown, the central metal sheet 7 is attached to the temporary carrier plate 11 using temporary bonding adhesive;

[0075] S3, as Figure 5 As shown, the first chip 2 is mounted on the central metal sheet 7 with its back side attached using a mounting adhesive or a mounting film;

[0076] S4, as Figure 6 As shown, the first chip 2 and the front and sides of the central metal sheet 7 are first integrally molded to form the first molded body;

[0077] S5, such as Figure 7 As shown, the temporary carrier board 11 is removed to expose the back of the central metal sheet 7. The second chip 3 is then attached to the back of the central metal sheet 7 with its back side using adhesive or film. A second overall molding process is performed to form a second molded body, covering the back of the second chip 3 and the central metal sheet 7.

[0078] S6, such as Figure 8 As shown, at least two rows of inner through holes 1001 are drilled on the molding compound 10. The inner through holes 1001 need to be aligned with the pre-drilled holes on the central metal sheet 7 to achieve electromagnetic shielding. At least two rows of outer through holes 1002 are drilled on the molding compound 10, with the outer through holes located outside the inner through holes. Figure 14 As shown, both the inner through holes 1001 and the outer through holes 1002 are in four rows, which can be arranged into a rectangle;

[0079] S7, such as Figure 9 As shown, metal is electroplated in the inner through hole 1001 to form an inner copper column 6, and metal is electroplated in the outer through hole 1002 to form an outer copper column 8.

[0080] S8, such as Figure 10 As shown, the front and back sides of the molding compound 10 are thinned until the first metal bump 201 and the second metal bump 301 are exposed, and the top of the first metal bump 201 is flush with the top of the inner row of copper pillars 6.

[0081] S9, such as Figure 11 As shown, a first rewiring layer 9 is made on the front side of the encapsulation body 10, so that the outer copper pillars 8 are interconnected with the first metal bump 201 on the front side. The surface of the first rewiring layer 9 is coated with a first insulating layer to insulate it from the outside world, while the inner copper pillars 6 are led out to the surface of the first insulating layer.

[0082] S10, such as Figure 12As shown, metal is sputtered onto the surface of the first insulating layer to form a first continuous shielding layer 1, which makes the first continuous shielding layer 1 conductive with the inner row of copper pillars 6, thereby achieving the shielding function;

[0083] S11, such as Figure 13 As shown, a second wiring layer 4 is fabricated on the back of the molding compound 10 to interconnect the outer copper pillars 8 with the second metal bump 301. A back pad for subsequent ball mounting is fabricated on the surface of the second wiring layer 4. Meanwhile, the inner copper pillars 6 are led out to the surface of the second wiring layer 4, and a grounding pad is fabricated on the surface of the second wiring layer 4.

[0084] S12, as Figure 1 As shown, solder balls 5 (solder balls) are formed on the back pad and the ground pad for interconnection with external circuit boards. The shielding layer can be connected to the system ground board through the shielding solder balls on the back.

Claims

1. A fan-out type package with a three-dimensional electromagnetic shielding structure, characterized in that: Including the encapsulated body covering the central metal sheet; The central metal sheet divides the internal space of the encapsulated body into an upper chamber and a lower chamber, and the edge of the central metal sheet is evenly provided with a number of pre-drilled holes that can be arranged in a rectangle. The upper chamber contains a first chip, and the lower chamber contains a second chip; The molding body has at least two rows of inner through holes corresponding to the pre-drilled holes in the central metal sheet, and the corresponding pre-drilled holes and inner through holes are provided with inner copper pillars that penetrate the molding body. The molding body has at least two rows of external through holes that penetrate the upper and lower end faces and are located outside the inner through holes. The external through holes are provided with external copper pillars that penetrate the molding body. The first metal bump and outer copper pillars of the first chip are provided with a first super-wiring layer. The first super-wiring layer is coated with a first insulating layer. A first continuous shielding layer is formed on the surface of the first insulating layer. The first continuous shielding layer is electrically connected to the top of all the inner copper pillars. A complete shielding plane is formed on the front of the molding compound. The second metal bump and the outer copper pillar of the second chip are provided with a second wiring layer to form the back pad; The bottom of the inner row of copper pillars is led out to the surface of the second wiring layer through the second wiring layer to form a grounding pad; Solder balls for interconnection with external circuit boards are provided on the back pads and ground pads; The central metal sheet, the inner row of copper pillars, the first continuous shielding layer on the front, and the grounding pads led out from the second wiring layer on the back together constitute a Faraday cage-like closed shielding cavity that can isolate the first chip and the second chip.

2. The fan-out package with a three-dimensional electromagnetic shielding structure according to claim 1, characterized in that: The central metal sheet is made of copper.

3. The fan-out package with a three-dimensional electromagnetic shielding structure according to claim 2, characterized in that: The first continuous shielding layer is made of photoresist.

4. The fan-out package with a three-dimensional electromagnetic shielding structure according to claim 1, characterized in that: The inner through holes are arranged in a rectangular shape.

5. The fan-out package with a three-dimensional electromagnetic shielding structure according to claim 4, characterized in that: The external through holes are arranged in a rectangular shape.

6. A method for preparing a fan-out type package with a three-dimensional electromagnetic shielding structure according to any one of claims 1-5, characterized in that: Includes the following steps: S1, a number of pre-drilled holes that can be arranged into a rectangle are evenly provided near the edge of the central metal sheet; S2, the central metal sheet is attached to the temporary carrier plate using temporary bonding adhesive; S3, the first chip is mounted onto the central metal plate with its back side using mounting adhesive or mounting film; S4, perform the first overall molding of the first chip and the front and sides of the central metal sheet; S5, remove the temporary carrier board to expose the back of the central metal sheet, and attach the second chip to the back of the central metal sheet with its back side using mounting adhesive or mounting film, and perform a second overall molding process to cover the back of the second chip and the central metal sheet. S6. Drill at least two rows of inner through holes on the molding compound. The inner through holes need to be aligned with the pre-drilled holes on the central metal sheet to achieve electromagnetic shielding. Drill at least two rows of outer through holes on the molding compound. The outer through holes are located outside the inner through holes. S7, inner copper pillars are formed by electroplating metal in the inner through holes, and outer copper pillars are formed by electroplating metal in the outer through holes. S8, thin the front and back of the plastic seal until the first metal bump and the second metal bump are exposed, and make the top of the first metal bump flush with the top of the inner row of copper pillars; S9, a first wiring layer is made on the front side of the encapsulation body, so that the outer row of copper pillars is interconnected with the first metal bump on the front side. The surface of the first wiring layer is coated with a first insulating layer to insulate it from the outside world, while the inner row of copper pillars is led out to the surface of the first insulating layer. S10, metal is sputtered onto the surface of the first insulating layer to form a first continuous shielding layer, making the first continuous shielding layer conductive with the inner row of copper pillars, thereby achieving the shielding function; S11, a second wiring layer is made on the back of the molding compound to interconnect the outer copper pillars with the second metal bump, and a back pad for subsequent ball mounting is made on the surface of the second wiring layer. At the same time, the inner copper pillars are led out to the surface of the second wiring layer, and a grounding pad is made on the surface of the second wiring layer. S12, solder balls are placed on the back pad and ground pad to form solder balls for interconnection with external circuit boards.

Images