An integrated packaging method, a flexible laminated substrate and a flexible circuit structure

Abstract

The application discloses an integrated packaging method, comprising: preparing a plurality of flexible substrates, each of which comprises a buried chip, a pad and a circuit; laminating and combining the plurality of flexible substrates into one, wherein each layer of the flexible substrates has a position corresponding pad; and making a metalized hole to electrically connect the position corresponding pads of each layer of the flexible substrates, to obtain a flexible laminated substrate. The application also discloses a flexible laminated substrate and a flexible circuit structure. Compared with the existing flip welding or wire bonding process, the application effectively reduces the height of a single module after packaging and the processing difficulty by embedding a flexible chip in a flexible substrate, laminating and combining multiple substrates, and then making a hole for interconnection.

Description

Technical Field

[0001] This invention belongs to the field of packaging technology, specifically relating to an integrated packaging method, a flexible laminated substrate, and a flexible circuit structure. Background Technology

[0002] With the rapid upgrading of electronic products, flexible printed circuit boards (FPCs) have become a cornerstone in the electronics and information industry due to their unique advantages, catering to the trend of lighter, thinner, shorter, and smaller electronic products. Also known as flexible circuit boards or flexographic circuit boards, FPCs offer advantages such as high wiring density, light weight, thinness, good flexibility, and fewer wiring space limitations, perfectly aligning with the development trend of electronic products and providing an effective solution for miniaturization. FPCs can be freely bent, rolled, and folded, and can withstand millions of dynamic bends without damaging the conductors. They can be assembled arbitrarily according to spatial layout requirements and can move and stretch freely in three-dimensional space, achieving integrated component assembly and wire connection.

[0003] However, existing flexible packaging structures, including those for chips, are either complex and difficult to manufacture, or have a high packaging height; at least one of these issues remains unresolved. For example, Chinese invention patent CN103681458B uses flexible packaging followed by thinning, which can lead to uneven thickness and chip breakage due to stress, resulting in high processing risks and difficulties, and also requiring thermoforming bonding. Another example is Chinese invention patent CN111128977A, which uses a metal columnar interconnect method. This method places extremely high demands on several factors, including the size and height of the metal columns, the size of the substrate opening, and the amount of solder paste used. In practice, this can lead to numerous defects such as metal column breakage, insufficient substrate opening for assembly with the metal frame, excessive solder paste, or poor soldering, making mass production impractical. Furthermore, modules made using this invention have low integration and a high height for each packaged chip. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an integrated packaging method, a flexible laminated substrate, and a flexible circuit structure.

[0005] Firstly, an integrated packaging method includes:

[0006] Prepare multiple flexible substrates, each of which includes embedded chips, pads, and circuits;

[0007] The plurality of flexible substrates are stacked together as a whole, wherein each of the flexible substrates has a corresponding pad;

[0008] Metallized vias are fabricated to electrically connect pads corresponding to the locations of each layer of the flexible substrate, thereby obtaining a flexible laminated substrate.

[0009] In one embodiment, the step of stacking and bonding the plurality of flexible substrates into a single unit includes:

[0010] Fabricate an adhesive film on a flexible substrate that needs to be laminated;

[0011] The multiple flexible substrates are bonded together by pressing with an adhesive film.

[0012] In one embodiment, the process of fabricating metallized vias to electrically connect pads corresponding to the locations of each layer of the flexible substrate includes:

[0013] Connecting vias are fabricated to connect the pads of each layer of the flexible substrate;

[0014] The connecting holes are metallized to interconnect the multilayer flexible substrates.

[0015] In one embodiment, surface mount components are mounted on a flexible substrate on the surface layer, the surface mount components including passive components.

[0016] In one embodiment, the surface mount component further includes a surface mount chip;

[0017] After mounting surface-mount components on the flexible substrate, the process further includes:

[0018] The mounted chip is interconnected with the pads of the flexible substrate on the surface layer via bonding wires.

[0019] In one embodiment, a flexible protective layer is formed on the surface of the flexible laminated substrate.

[0020] In one embodiment, the flexible laminated substrate is cut into shape and bent and stacked into a three-dimensional stacked structure;

[0021] An encapsulation structure is fabricated around the three-dimensional stacked structure.

[0022] Secondly, the flexible laminated substrate is obtained by the aforementioned integrated packaging method.

[0023] In one embodiment, the thickness of the flexible substrate is no greater than 100 μm.

[0024] Thirdly, the flexible circuit structure is a three-dimensional stacked structure formed by cutting and bending the aforementioned flexible laminated substrate.

[0025] In one embodiment, an encapsulation structure is further provided around the three-dimensional stacked structure.

[0026] In one embodiment, the flexible circuit structure includes multiple circuit modules connected by PCB traces, the multiple circuit modules being stacked sequentially according to their area size.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] By embedding flexible chips within a flexible substrate and stacking multiple substrate layers together, and then establishing interlayer electrical connections through metallized vias, the height of the flexible circuit structure after packaging is effectively reduced, achieving ultra-small integrated packaging, and the processing difficulty is also reduced. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of step 1 of the integrated packaging method of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure after adhesive application in step 2 of the integrated packaging method of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure after lamination in step 2 of the integrated packaging method of the present invention;

[0033] Figure 4 This is a structural schematic diagram of step 3 of the integrated packaging method of the present invention;

[0034] Figure 5 This is a structural schematic diagram of step 4 of the integrated packaging method of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure after mounting in step 5 of the integrated packaging method of the present invention;

[0036] Figure 7 This is a schematic diagram of the structure after wire bonding in step 5 of the integrated packaging method of the present invention;

[0037] Figure 8 This is a schematic diagram of step 6 of the integrated packaging method of the present invention and a schematic diagram of the flexible laminated substrate.

[0038] Figure 9 This is a schematic diagram of the structure after cutting and forming in step 7 of the integrated packaging method of the present invention;

[0039] Figure 10 This is a schematic diagram of the structure after bending and stacking in step 7 of the integrated packaging method of the present invention;

[0040] Figure 11 This is a flowchart illustrating an integrated packaging method according to the present invention.

[0041] Among them, 1. Flexible substrate; 11. Pad; 12. Embedded chip; 13. Interconnect line; 14. First flexible dielectric layer; 15. Second flexible dielectric layer; 16. Through hole; 161. Electroplated metal layer; 17. Passive device; 18. Surface mount chip; 19. Flexible protective layer; 10. Bonding wire; 2. Adhesive layer; 3. Flexible circuit structure; 31. PCB trace; 32. Circuit module. Detailed Implementation

[0042] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] Firstly, an integrated packaging method, such as Figure 11 As shown, it includes:

[0045] Step 1: Prepare multiple flexible substrates 1, each of which includes circuitry, pads 11, embedded chips 12 pre-embedded in the flexible substrate 1, and interconnect lines 13, such as... Figure 1 As shown.

[0046] The flexible substrate can be pre-embedded with a chip in the first flexible dielectric layer 14 using CIP (chip-in-polymer) technology, and corresponding pads can be fabricated. Interconnect lines 13 for connecting the pads and the chip are fabricated on the second dielectric layer 15. Multiple flexible substrates 1 have corresponding pads 11 for subsequent alignment and lamination. Corresponding circuits are already fabricated on the flexible substrate 1. The embedded chip 12 is a flexible, ultra-thin chip, generally with a thickness of no more than 50 μm.

[0047] Step 2: The multiple flexible substrates 1 are stacked and bonded together with adhesive, wherein each layer of the flexible substrate 1 has a corresponding pad 11.

[0048] Among these, an adhesive film for interlayer bonding can be fabricated on the flexible substrate 1 that needs to be laminated, such as... Figure 2As shown; and multiple flexible substrates 1 are bonded together by adhesive film through pressing, as shown. Figure 3 As shown. Each flexible substrate 1 has corresponding pads 11 for subsequent connection. The lamination can be performed using a vacuum press. The adhesive film becomes the bonding layer 2.

[0049] Step 3: Fabricate connecting holes 16 to connect the pads 11 of each layer of the flexible substrate 1, such as... Figure 4 As shown.

[0050] The connecting hole 16 can be made by mechanical drilling or laser drilling, and the area where the hole is made is the pad 11 of each layer of flexible substrate 1.

[0051] Step 4: Metallize the connecting holes 16 to interconnect the multilayer flexible substrates 1, thus obtaining a flexible laminated substrate, such as... Figure 5 As shown.

[0052] The connecting hole 16 can be metallized by electroplating to obtain an electroplated metal layer 161, and an electrical connection is formed between the pads 11 of each flexible substrate 1.

[0053] Step 5: Surface mount components can be mounted on the flexible substrate 1, including passive components 17, such as... Figure 6 As shown.

[0054] The surface-mount components on the flexible substrate 1 include at least passive components 17, and may also include surface-mount chips 18 not embedded in the flexible substrate. The mounting can be performed using SMT (Surface Mount Technology). The passive components can be mounted on interconnect lines 13 connected to the pads 11. This step is optional and can be skipped if no surface-mount components need to be mounted.

[0055] Step 6: Fabricate a flexible protective layer 19 on the surface of the flexible laminated substrate, such as... Figure 8 As shown.

[0056] The flexible protective layer 19 can be fabricated by coating the surface of the flexible laminated substrate with a flexible material, such as silicone. This step is optional, and the flexible protective layer 19 can protect surface-mount components on the flexible laminated substrate.

[0057] Step 7: Cut the flexible laminated substrate into shape and bend and stack it into a three-dimensional stacked structure, such as... Figure 9-10 As shown.

[0058] The flexible laminated substrate can be cut into a flexible circuit structure 3 composed of several circuit modules 32 connected by PCB traces 31, such as... Figure 9 As shown; a portion of the PCB trace 31 can be bent, and the various circuit modules 32 in the flexible circuit structure 3 are stacked three-dimensionally through bending, as shown. Figure 10 As shown. The circuit modules 32 can be linearly connected or cross-connected, and can be stacked sequentially according to the area occupied by the circuit modules 32 to form a three-dimensional stacked structure.

[0059] Step 8: Create an encapsulation structure around the three-dimensional stacked structure.

[0060] The encapsulation structure can be fabricated by coating a flexible or rigid material, such as silicone rubber or epoxy resin, onto the periphery of the three-dimensional stacked structure.

[0061] In one embodiment, in step 5, the surface mount component may further include a surface mount chip 18, such as... Figure 6 , 7 As shown. It also includes step 5.1: interconnecting the mounted chip 18 with the pads 11 of the flexible substrate 1 of the surface layer through bonding wires 10.

[0062] The mounted chip 18 refers to a chip that is not embedded in the flexible substrate 1 but is mounted on the flexible substrate 1 using a mounting method. For example, the mounted chip 18 is attached to the first flexible dielectric layer 14, such as... Figure 6 As shown; then connect the mounted chip 18 to the pad 11 by wire bonding, as follows. Figure 7 As shown.

[0063] One aspect of the integrated packaging method combines flexible circuit board manufacturing process and chip integrated circuit manufacturing process, embeds the chip in a flexible substrate to form an ultra-thin chip packaging substrate, then presses two or more flexible substrates together, interconnects the layers of flexible substrates by making metallized holes, and then folds the flexible substrates to form a three-dimensional stacked system-level flexible packaging product of ultra-thin chip.

[0064] This method combines CIP (Chip in Polymer) technology with ultra-thin chips, which can reduce the thickness of a single flexible substrate to less than 100μm. This not only greatly reduces the height of the packaged flexible circuit structure, but also reduces the processing difficulty.

[0065] Secondly, flexible laminated substrates, such as Figure 8 As shown, the flexible substrate 1 includes multiple layers of interconnected flexible substrates, the flexible substrate 1 including embedded chips 12, pads 11 and circuits; it also includes metallized vias, the metallized vias connecting the pads 11 of each layer of the flexible substrate 1.

[0066] The metallized via refers to a through-hole 16 structure with an electroplated metal layer 161. The flexible laminated substrate, through techniques such as embedding the chip in the flexible substrate, stacking multiple flexible substrates, and establishing interlayer electrical connections via metallized vias, can achieve ultra-small integrated packaging, significantly reducing the height of the packaged flexible circuit structure. It is also easier to process without the need for special processes.

[0067] In one embodiment, the multilayer flexible substrates 1 are connected to each other by an adhesive layer 2.

[0068] The flexible laminated substrate includes a flexible substrate 1 and an adhesive layer 2. The adhesive layer 2 can be an adhesive film. Specifically, an adhesive film for interlayer bonding can be fabricated on the flexible substrate 1 that needs to be laminated, and multiple flexible substrates 1 can be bonded together by the adhesive film to form a multi-layer flexible laminated substrate.

[0069] In one embodiment, a surface mount component is attached to the flexible substrate 1 on the surface, the surface mount component including a passive component 17.

[0070] The components mounted on the surface of the flexible substrate 1 include at least passive components 17, and may also include chips not embedded in the flexible substrate. The mounting can be performed using SMT (Surface Mount Technology).

[0071] In one embodiment, the surface mount component further includes a mounting chip 18, which is interconnected with the pads 11 of the flexible substrate 1 on the surface layer via bonding wires 10.

[0072] The mounted chip 18 refers to a chip that is not embedded in the flexible substrate but is mounted on the flexible substrate 1 using a mounting method. The mounted chip 18 is wire-connected to the pads 11.

[0073] In one embodiment, the flexible substrate 1 of the surface layer is further provided with a flexible protective layer 19 for covering the surface-mounted components.

[0074] The flexible protective layer 19 can be made by coating a flexible material, such as silicone, onto the surface of the flexible substrate 1. The flexible protective layer 19 provides protection for surface-mounted components.

[0075] Thirdly, the flexible circuit structure can be obtained by cutting and shaping any of the flexible laminated substrates described in the second aspect.

[0076] The flexible laminated substrate can be cut into a flexible circuit structure composed of several circuit modules 32 connected by PCB traces 31, such as... Figure 9 As shown. The flexible circuit structure can be bent and stacked, or not, depending on the specific circumstances.

[0077] In one embodiment, the flexible circuit structure is a three-dimensional stacked structure formed by bending and stacking.

[0078] The PCB traces 31 are partially bendable, and the circuit modules 32 in the flexible circuit structure are stacked three-dimensionally through bending. The circuit modules 32 can be connected in a straight line or cross-connected; the circuit modules 32 can be stacked sequentially according to their area to form a three-dimensional stacked structure; for example, such as... Figure 10 As shown, the area of ​​the multiple circuit modules 32 in the three-dimensional stacked structure gradually decreases from the bottom layer to the top layer.

[0079] In one embodiment, an encapsulation structure is further provided around the three-dimensional stacked structure.

[0080] The encapsulation structure can be fabricated by coating a flexible or rigid material, such as silicone rubber or epoxy resin, onto the periphery of the three-dimensional stacked structure.

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. An integrated packaging method, characterized in that, include: Prepare multiple flexible substrates, each of which includes embedded chips, pads, and circuits; The plurality of flexible substrates are stacked together as a whole, wherein each of the flexible substrates has a corresponding pad; Metallized vias are fabricated to electrically connect pads corresponding to the positions of each layer of the flexible substrate, thereby obtaining a flexible laminated substrate; The flexible laminated substrate is cut into a flexible circuit structure consisting of several circuit modules connected by PCB traces. Part of the PCB traces is used for bending, so that the circuit modules are bent and stacked into a three-dimensional stacked structure. The circuit modules are stacked sequentially according to the size of the area they occupy.

2. The integrated packaging method according to claim 1, characterized in that: The process of stacking and bonding the plurality of flexible substrates into one unit includes: Fabricate an adhesive film on a flexible substrate that needs to be laminated; The multiple flexible substrates are bonded together by pressing with an adhesive film.

3. The integrated packaging method according to claim 1, characterized in that: The process of fabricating metallized vias to electrically connect pads at the locations corresponding to each layer of the flexible substrate includes: Connecting vias are fabricated to connect the pads of each layer of the flexible substrate; The connecting holes are metallized to interconnect the multilayer flexible substrates.

4. The integrated packaging method according to claim 1, characterized in that: Surface mount components are mounted on a flexible substrate, including passive components.

5. The integrated packaging method according to claim 4, characterized in that: The surface mount components also include surface mount chips; After mounting surface-mount components on the flexible substrate, the process further includes: The mounted chip is interconnected with the pads of the flexible substrate on the surface layer via bonding wires.

6. The integrated packaging method according to claim 4, characterized in that, Also includes: A flexible protective layer is formed on the surface of the flexible laminated substrate.

7. An integrated packaging method according to any one of claims 1-6, characterized in that, Also includes: An encapsulation structure is fabricated around the three-dimensional stacked structure.

8. A flexible laminated substrate, characterized in that: It is obtained by an integrated packaging method according to any one of claims 1-6.

9. The flexible laminated substrate according to claim 8, characterized in that: The thickness of the flexible substrate is no greater than 100 μm.

10. A flexible circuit structure, characterized in that, It is a three-dimensional stacked structure formed by cutting and bending the flexible laminated substrate as described in any one of claims 8-9.

11. The flexible circuit structure according to claim 10, characterized in that: An encapsulation structure is also provided around the three-dimensional stacked structure.

12. The flexible circuit structure according to claim 10, characterized in that: The flexible circuit structure includes multiple circuit modules connected by PCB traces, which are stacked sequentially according to their area size.

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