A three-dimensional stacking packaging method based on flexible substrate

Abstract

The present invention relates to the technical field of three-dimensional stacked packaging, and proposes a three-dimensional stacked packaging method based on a flexible substrate, comprising the following steps: constructing a plurality of flexible substrates; arranging a first flip chip on a first surface of the flexible substrate; arranging a heat dissipation member, wherein the flexible substrate is folded so as to connect the heat dissipation member to the first flip chip; arranging a second flip chip on a second surface of the flexible substrate; and folding the heat dissipation member so as to connect the second flip chip to the heat dissipation member.

Description

Technical Field

[0001] The present invention generally relates to the field of three-dimensional stacking packaging technology. Specifically, the present invention relates to a three-dimensional stacking packaging method based on a flexible substrate. Background Art

[0002] Traditionally, three-dimensional stacking of flip chips (FC) usually includes the following technical solutions: connecting multiple chips through through silicon vias (TSV); stacking assembly through multi-layer substrates (POP, Package on Package); and repeatedly folding the flexible substrate and placing the chips in the gaps created by the folding.

[0003] However, the above-mentioned technical solution still has the following technical problems: the process of connecting multiple chips through silicon vias is complex and costly; during the stacking and assembly of multi-layer substrates, the large differences in thermal expansion coefficients between different packaging materials will cause warping, and the degree of warping will increase with the number of stacked layers, which will aggravate ball soldering defects; in addition, the process of repeatedly folding the flexible substrate and placing the chips in the gaps created by the folds usually makes the substrate too long and the production yield is low. Summary of the Invention

[0004] To at least partially solve the above-mentioned problems in the prior art, the present invention proposes a three-dimensional stacking packaging method based on a flexible substrate, the method comprising the following steps:

[0005] constructing a plurality of flexible substrates;

[0006] Arranging a first flip chip on the first surface of the flexible substrate;

[0007] Arranging a heat dissipation member, wherein the heat dissipation member is connected to the first flip chip by folding the flexible substrate;

[0008] Arranging a second flip chip on the second surface of the flexible substrate; and

[0009] The heat dissipation member is folded to connect the second flip chip to the heat dissipation member.

[0010] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate includes constructing a first flexible substrate and a second flexible substrate, wherein pad openings are provided on the first and second surfaces of the first flexible substrate and the second flexible substrate, and the pad openings are configured to arrange first and second flip chips.

[0011] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate includes mounting the first flip chip on the first flexible substrate and the second flexible substrate and performing reflow soldering, wherein the first flip chip includes first to fourth chips;

[0012] A first chip and a second chip are arranged on the first surface of the first flexible substrate, wherein the first chip and the second chip are connected to the first flexible substrate via chip bumps;

[0013] Arranging a third chip and a fourth chip on the first surface of the second flexible substrate, wherein the third chip and the fourth chip are connected to the second flexible substrate via chip bumps; and

[0014] The gaps at the chip bumps are filled with filling glue.

[0015] In one embodiment of the present invention, arranging the heat dissipation component includes:

[0016] connecting the heat dissipation component to the fourth chip and the second chip via a first die-bonding adhesive film, and heating and curing the first die-bonding adhesive film;

[0017] Arranging a second die-bonding adhesive film on surfaces of the third chip and the first chip; and

[0018] The first flexible substrate and the second flexible substrate are folded so that the second die-bonding adhesive film is connected to the heat dissipation member, and the second die-bonding adhesive film is heated and cured.

[0019] In one embodiment of the present invention, it is provided that the second flip chip includes a fifth and a sixth chip;

[0020] The fifth chip is mounted on the second surface of the second flexible substrate and reflow soldering is performed; and

[0021] A sixth chip is mounted on the second surface of the first flexible substrate and reflow soldering is performed.

[0022] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate includes:

[0023] folding the heat dissipation member so as to closely contact the surface of the fifth chip, disposing a third die-bonding adhesive film, and heating and curing the third die-bonding adhesive film to connect the heat dissipation member and the fifth chip;

[0024] turning the first flexible substrate over to be above the second flexible substrate;

[0025] Arranging a fourth die-bonding film on the surface of the sixth chip; and

[0026] The sixth chip is connected to the heat dissipation component and the fourth die-bonding adhesive film is heated and cured.

[0027] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate further includes mounting a ball grid array on the second surface of the second flexible substrate and performing reflow soldering.

[0028] In one embodiment of the present invention, the flexible substrate-based three-dimensional stacking packaging method includes connecting the ball grid array to the first flexible substrate.

[0029] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate further includes arranging solder balls on the second surface of the second flexible substrate.

[0030] In one embodiment of the present invention, the three-dimensional stacking packaging method based on a flexible substrate further comprises plastic-sealing the flexible substrate, the first and second flip chips, and the heat dissipation component.

[0031] This invention combines multiple flexible substrates with a POP stacking process to stack chips. Due to the low rigidity of the flexible substrates, warping during stacking, often caused by large differences in thermal expansion coefficients between different materials, is avoided. Furthermore, the use of multiple flexible substrates allows each flexible substrate to be folded only a few times during stacking. This significantly improves product yield compared to existing solutions using a single substrate.

[0032] The present invention also produces the following unexpected benefits: Conventional solutions using a single substrate require modifications to the entire substrate when some chips need to be changed, resulting in inflexible configuration and long production cycles. However, the present invention utilizes multiple flexible substrates, so when individual chips need to be modified, only the design of the corresponding flexible substrate needs to be adjusted, significantly shortening the production cycle. Furthermore, the heat dissipation component of the present invention can be inserted between the chips in the composite packaging structure and can be connected to the outside, significantly improving heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To further illustrate the advantages and features of various embodiments of the present invention, a more detailed description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings depict only typical embodiments of the present invention and are not to be considered as limiting the scope of the present invention. In the drawings, for clarity, identical or corresponding components will be represented by the same or similar reference numerals.

[0034] Figure 1 A schematic flow chart of a three-dimensional stacking packaging method based on a flexible substrate in one embodiment of the present invention is shown.

[0035] Figure 2-5 A schematic diagram of the process structure of a three-dimensional stacked packaging structure in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0036] It should be noted that the components in the drawings may be shown exaggeratedly for the sake of illustration and are not necessarily correct to scale. In the drawings, identical or functionally identical components are provided with the same reference numerals.

[0037] In the present invention, unless otherwise specified, the phrases "disposed on," "disposed above," and "disposed above" do not exclude the presence of intermediate components. Furthermore, "disposed on or above" merely indicates the relative positional relationship between two components and, in certain circumstances, such as after reversing the product orientation, can be converted to "disposed below or below," and vice versa.

[0038] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0039] In the present invention, unless otherwise specified, the quantifiers "a" and "an" do not exclude the presence of multiple elements.

[0040] It should also be noted that in the embodiments of the present invention, for the sake of clarity and simplicity, only a portion of the parts or components may be shown, but those skilled in the art will understand that, under the teachings of the present invention, the required parts or components can be added according to the needs of the specific scenario. In addition, unless otherwise stated, the features of different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can be used to replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment also falls within the scope of disclosure or description of this application.

[0041] It should also be noted that, within the scope of the present invention, terms such as "same," "equal," and "equal to" do not imply absolute equality of values, but rather allow for a certain reasonable error. In other words, such terms also encompass "substantially the same," "substantially equal," and "substantially equal." Similarly, in the present invention, terms such as "perpendicular to" and "parallel to" indicating direction also encompass the meaning of "substantially perpendicular to" and "substantially parallel to."

[0042] In addition, the numbering of the steps of the methods of the present invention does not limit the order in which the steps are to be performed. Unless otherwise specified, the steps of the methods may be performed in different orders.

[0043] The present invention will be further described below with reference to the accompanying drawings in conjunction with specific embodiments.

[0044] Figure 1 FIG1 shows a flow chart of a three-dimensional stacking packaging method based on a flexible substrate in one embodiment of the present invention. Figure 1 As shown, the method may include the following steps:

[0045] Step 100: constructing a plurality of flexible substrates, which may include:

[0046] A first flexible substrate 101 and a second flexible substrate 102 are constructed, each having pad openings thereon. These pad openings can be used to arrange chips. The pad openings are located on the first and second surfaces of the first and second flexible substrates 101 and 102. While the above embodiment uses two flexible substrates as an example, those skilled in the art will appreciate that, based on the technical solutions of the present invention, it is also conceivable to construct three or even more flexible substrates.

[0047] Step 200: Arrange a first flip chip on the first surface of the flexible substrate. Figure 2 As shown, these may include:

[0048] A first flip chip is mounted on the first flexible substrate 101 and the second flexible substrate 102 and reflow soldered. The first flip chip may include a first chip 105, a second chip 109, a third chip 116, and a fourth chip 118. The first chip 105 and the second chip 109 may be arranged on the first surface of the first flexible substrate 101, and the third chip 116 and the fourth chip 118 may be arranged on the first surface of the second flexible substrate 102. The first chip 105 and the second chip 109 are connected to the first flexible substrate 101 via chip bumps 104, and the third chip 116 and the fourth chip 118 are connected to the second flexible substrate 102 via chip bumps 104. Furthermore, gaps at the chip bumps 104 may be filled with filler 103.

[0049] Step 300: Arrange a heat dissipation component, wherein the heat dissipation component is connected to the first flip chip by folding the flexible substrate. Figure 3 As shown, these may include:

[0050] The heat dissipation member 114 is connected to the surfaces of the fourth chip 118 and the second chip 109 via a first die attach film (DAF), and the first die attach film is heated and cured.

[0051] A second die-bonding film is arranged on the surfaces of the third chip 116 and the first chip 105 , the first flexible substrate 101 and the second flexible substrate 102 are folded so that the second die-bonding film is in contact with and connected to the heat dissipation member 114 , and the second die-bonding film is heated and cured.

[0052] Step 400: Arrange a second flip chip and a ball grid array (BGA) on the second surface of the flexible substrate, such as Figure 4 As shown, the second flip chip may include a fifth chip 115 and a sixth chip 110, and the step may include:

[0053] The fifth chip 115 and the ball grid array 112 are mounted on the second surface of the second flexible substrate 102 and reflow soldering is performed.

[0054] And the sixth chip 110 is mounted on the second surface of the first flexible substrate 101 and reflow soldering is performed.

[0055] Step 500: Fold the heat dissipation component to connect the second flip chip to the heat dissipation component. Figure 5 As shown, these may include:

[0056] The heat dissipation member 114 is folded so that the protruding portion of the heat dissipation member 114 is in close contact with the surface of the fifth chip 115 , and a third die-bonding film is arranged and heated and cured to connect the heat dissipation member 114 and the fifth chip 115 .

[0057] The first flexible substrate 101 is flipped over to be above the second flexible substrate 102 , a fourth die-bonding film is arranged on the surface of the sixth chip 110 , the sixth chip 110 is brought into contact with the heat dissipation component 114 and the fourth die-bonding film is heated and cured.

[0058] Step 600: Connecting the ball grid array 112 to the first flexible substrate 101, which may include:

[0059] The ball grid array 112 is reflowed so as to be fully bonded to the pads on the second surface of the first flexible substrate 101 .

[0060] Through steps 100 to 600 , the construction of a package body can be completed. The package body includes a flexible substrate, first and second flip chips, and a heat dissipation member.

[0061] Step 700 : Plastic-encapsulate the package body, and arrange solder balls 113 on the second surface of the second flexible substrate 102 .

[0062] Although various embodiments of the present invention have been described above, it should be understood that they are presented by way of example only and not limitation. It will be apparent to those skilled in the relevant art that various combinations, modifications, and variations may be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely in accordance with the appended claims and their equivalents.

Claims

1. A three-dimensional stacking packaging method based on a flexible substrate, characterized in that: The following steps are involved: constructing a plurality of flexible substrates; Arranging a first flip chip on the first surface of the flexible substrate; Arranging a heat dissipation member, wherein the heat dissipation member is connected to the first flip chip by folding the flexible substrate; Arranging a second flip chip on the second surface of the flexible substrate; as well as The heat dissipation component is folded onto itself to form a bent structure, and the second flip chip is connected to the heat dissipation component.

2. The three-dimensional stacking packaging method based on a flexible substrate according to claim 1, characterized in that: The method includes constructing a first flexible substrate and a second flexible substrate, wherein pad openings are provided on first and second surfaces of the first flexible substrate and the second flexible substrate, and the pad openings are configured to arrange first and second flip chips.

3. The three-dimensional stacking packaging method based on a flexible substrate according to claim 2, characterized in that: The method includes mounting the first flip chip on the first flexible substrate and the second flexible substrate and performing reflow soldering, wherein the first flip chip includes first to fourth chips; A first chip and a second chip are arranged on the first surface of the first flexible substrate, wherein the first chip and the second chip are connected to the first flexible substrate via chip bumps; Arranging a third chip and a fourth chip on the first surface of the second flexible substrate, wherein the third chip and the fourth chip are connected to the second flexible substrate via chip bumps; as well as The gaps at the chip bumps are filled with filling glue.

4. The three-dimensional stacking packaging method based on a flexible substrate according to claim 3, characterized in that: Arranging the heat dissipation components includes: connecting the heat dissipation component to the fourth chip and the second chip via a first die-bonding adhesive film, and heating and curing the first die-bonding adhesive film; Arranging a second die-bonding adhesive film on surfaces of the third chip and the first chip; and The first flexible substrate and the second flexible substrate are folded so that the second die-bonding adhesive film is connected to the heat dissipation member, and the second die-bonding adhesive film is heated and cured.

5. The three-dimensional stacking packaging method based on a flexible substrate according to claim 4, characterized in that: The second flip chip includes a fifth and a sixth chip; The fifth chip is mounted on the second surface of the second flexible substrate and reflow soldering is performed; and A sixth chip is mounted on the second surface of the first flexible substrate and reflow soldering is performed.

6. The three-dimensional stacking packaging method based on a flexible substrate according to claim 5, characterized in that: include: folding the heat dissipation member so as to closely contact the surface of the fifth chip, disposing a third die-bonding adhesive film, and heating and curing the third die-bonding adhesive film to connect the heat dissipation member and the fifth chip; turning the first flexible substrate over to be above the second flexible substrate; Arranging a fourth die-bonding film on the surface of the sixth chip; as well as The sixth chip is connected to the heat dissipation component and the fourth die-bonding adhesive film is heated and cured.

7. The three-dimensional stacking packaging method based on a flexible substrate according to claim 6, characterized in that: The method also includes mounting a ball grid array on the second surface of the second flexible substrate and performing reflow soldering.

8. The three-dimensional stacking packaging method based on a flexible substrate according to claim 7, characterized in that: The method includes reflowing the ball grid array and connecting it to the first flexible substrate.

9. The three-dimensional stacking packaging method based on a flexible substrate according to claim 8, characterized in that: The method further includes arranging solder balls on the second surface of the second flexible substrate.

10. The three-dimensional stacking packaging method based on a flexible substrate according to claim 1, characterized in that: The method further includes plastic-sealing the flexible substrate, the first and second flip chips, and the heat dissipation component.

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