Wafer level injection molding method of plastic through hole package substrate and plastic through hole package substrate
By combining wafer-level injection molding with dicing and injection molding processes, a coreless plastic through-hole packaging substrate was fabricated, solving the problems of high cost and weak interlayer bonding in existing technologies, and realizing high-density electrical interconnection and multilayer wiring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUXI ZHONGWEI GAOKE ELECTRONICS
- Filing Date
- 2022-07-26
- Publication Date
- 2026-06-02
AI Technical Summary
Existing plastic through-hole packaging technology is costly and cannot be applied to wafer-level injection molding. Furthermore, the interlayer bonding of coreless plastic encapsulation substrates is weak, resulting in a small number of wiring layers and making it impossible to achieve extremely multilayer wiring.
Using a wafer-level injection molding method, copper traces and copper pillar structures are prepared by coating a polyimide layer on a carrier board. Combined with dicing and injection molding processes, a coreless plastic through-hole packaging substrate is formed, realizing the connection and encapsulation of the first and second traces.
It enhances interlayer bonding strength, enables higher density electrical interconnection, is suitable for multi-layer cabling, and reduces costs.
Smart Images
Figure CN115332086B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit packaging technology, and in particular to a wafer-level injection molding method for plastic through-hole packaging substrates. Background Technology
[0002] Conventional packaging substrates serve as the medium for primary interconnection between chips and printed circuit boards (PCBs). As integrated circuit packaging technology increasingly moves towards three-dimensionality, the structure of packaging substrates is required to possess characteristics such as multiple layers, high density, vertical transmission, and fan-out. Currently, substrates with through-holes can be classified by material into through-silicon via (TSV) substrates, plastic through-hole (TMV) substrates, and glass through-hole (TGV) substrates, among others.
[0003] Unlike the TSV and TGV substrates which use electroplating after etching for through-holes, TMV substrates employ a multi-layer electroplating method for through-holes. To facilitate operation and simplify the process, resin films are commonly used as insulating materials between metal lines. However, the low operating pressure of resin films leads to cracking and delamination between substrate layers, preventing the creation of extremely multilayered plastic substrates due to severe warping. To address this issue, cored plastic substrates are typically used—multilayered resin substrates containing rigid layers such as glass, silicon, and metal as the core. These substrates offer high structural strength, are less prone to warping, and enable extremely multilayer wiring. In related technologies, injection molding, also known as molding, is a common method for plastic encapsulation. Higher operating pressure effectively enhances interlayer bonding, facilitating extremely multilayer wiring on plastic substrates. To improve production efficiency, plastic substrates are mostly packaged at the wafer level.
[0004] However, existing through-hole (TBV) encapsulation technologies require the core material to be coupled with TSV, TGV, and other processes to connect the upper and lower resin layers for wiring, resulting in excessive costs. Furthermore, because the size of the wafer-level injection mold is exactly the same as the wafer size, it is often used in wafer reconstruction processes and cannot be used for existing wafers. For example, a 12-inch wafer cannot be placed into a 12-inch injection mold. Therefore, there is an urgent need to develop a wafer-level injection molding method suitable for TMV substrates. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a wafer-level injection molding method for plastic through-hole encapsulation substrates, making the coreless plastic encapsulation substrate solution compatible with the injection molding process, and solving the problems of weak interlayer bonding and few wiring layers in coreless plastic encapsulation.
[0006] According to the technical solution provided by the present invention, in one aspect, a wafer-level injection molding method for a plastic through-hole encapsulation substrate is provided, the method comprising:
[0007] Step 1: Coat the upper surface of the carrier plate with a polyimide (PI) layer;
[0008] Step 2: Prepare the first trace and the dicing copper trace on the upper surface of the PI layer. The first trace is a copper circuit, and the dicing copper trace is used to define the size of the plastic packaging substrate.
[0009] Step 3: Fabricate at least one copper pillar structure on the first trace;
[0010] Step 4: Cut the carrier board based on the dicing copper wires to obtain the cut structure;
[0011] Step 5: Perform injection molding on the cut structure to obtain an injection molding layer. The top surface of the injection molding layer is flush with the top surface of the copper column structure.
[0012] Step 6: Prepare a second trace on the upper surface of the copper pillar structure. The second trace is a copper circuit.
[0013] Step 7: Thin the carrier board and PI layer in the cutting structure to expose the first trace, so as to obtain the injection-molded plastic through-hole encapsulation substrate.
[0014] On the other hand, a plastic through-hole packaging substrate is provided, which is basically prepared by the above-mentioned plastic through-hole packaging substrate by wafer-level injection molding method. The plastic through-hole packaging substrate includes a first trace, a second trace, and a copper pillar structure.
[0015] The first trace is located on the first surface of the substrate, and the second trace is located on the second surface of the substrate.
[0016] The first and second cables are connected by a copper pillar structure;
[0017] The first wiring and copper pillar structure are wrapped in injection molding.
[0018] The second trace is enclosed by a PI layer.
[0019] The beneficial effects of the technical solution provided by this invention include at least the following:
[0020] By flexibly applying the dicing process, combining wafer-level redistribution technology, wafer-level TMV technology, and injection molding technology, wafer-level injection molding of coreless TMV substrates is achieved. Compared with the traditional resin film lamination method, the interlayer bonding strength of the injection molding method is greatly enhanced, which helps to achieve higher density electrical interconnection. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.
[0022] Figure 1 This is a schematic diagram of the structure of a plastic through-hole encapsulation substrate provided by the present invention.
[0023] Figure 2 This is a schematic flowchart of a wafer-level injection molding method for a plastic through-hole encapsulation substrate provided by the present invention.
[0024] Figure 3 This is a schematic cross-sectional view of a packaging substrate used in the fabrication of the first wiring process, as provided by the present invention.
[0025] Figure 4 This is a schematic cross-sectional view of the packaging substrate for a process of creating a planted copper structure, as provided by the present invention.
[0026] Figure 5 This is a schematic cross-sectional view of a packaging substrate during a dicing process provided by the present invention.
[0027] Figure 6 This is a schematic cross-sectional view of a packaging substrate after the injection molding process, provided by the present invention.
[0028] Figure 7 This is a schematic cross-sectional view of a packaging substrate used in the fabrication of a second wiring process, as provided by the present invention.
[0029] Figure 8 This is a top view schematic diagram of a packaging substrate with scriber copper wires provided by the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
[0031] This invention is used to manufacture a plastic through-hole encapsulation substrate. Figure 1 This diagram illustrates the structure of a plastic through-hole encapsulation substrate provided by the present invention. Please refer to it. Figure 1 The plastic through-hole encapsulation substrate includes a first trace 10, a second trace 20, and a copper pillar structure 101; the first trace 10 is located on the first surface of the substrate, and the second trace 20 is located on the second surface of the substrate. The first trace 10 and the second trace 20 are connected by the copper pillar structure 101. The first trace 10 and the copper pillar structure 101 are encapsulated by an injection molding layer 14, and the second trace 20 is encapsulated by a PI layer 21. Figure 1In the structure shown, the first trace 10 and the second trace 20 are located on opposite sides of the substrate and are electrically connected through the copper pillar structure 101 within the package substrate. Both are encapsulated by the injection molding layer 14 and the PI layer 21. After being connected to other electrical components, they can perform corresponding functions. Correspondingly, the structure also includes some diced copper lines 13.
[0032] Figure 2 This is a schematic flowchart of a wafer-level injection molding method for a plastic through-hole encapsulation substrate provided by the present invention. This method is used to prepare, for example, a wafer-level injection molding method for a plastic through-hole encapsulation substrate. Figure 1 The plastic through-hole encapsulation substrate shown in the figure, the method includes:
[0033] Step 1: Coat the upper surface of the carrier board with a PI layer.
[0034] In the embodiments of the present invention, please refer to Figure 3 The carrier plate 11 can be realized as a silicon wafer. After coating the carrier plate 11 with PI material 12, the PI resin can enhance the bonding force between the first trace 10 and the carrier plate 11 in subsequent fabrication.
[0035] Step 2: Prepare the first trace and diced copper lines on the upper surface of the PI layer.
[0036] In this embodiment of the invention, the first trace is a copper trace, and the diced copper trace is used to define the size of the plastic encapsulation substrate.
[0037] In this embodiment of the invention, the process of preparing the first trace and the scribe line copper wire can be implemented as a combination of various processes. In one example, the process includes sputtering, photolithography, electroplating, and wet plating. The sputtering process involves sputtering a titanium seed layer or a copper seed layer on top of the PI layer; the photolithography process involves spin-coating a layer of Photoresist negative photoresist and obtaining the opening regions of the first trace copper wire 10 and the peripheral scribe line 13 after development; the electroplating process involves forming the line corresponding to the first trace and the scribe line copper wire in the opening region obtained by the photolithography process; the wet plating process involves removing excess pre-material, leaving only the first trace and the scribe line copper wire protruding from the upper surface of the PI layer. After preparing the first trace and the scribe line copper wire, the implementation of the scheme is as follows: Figure 3 As shown. In this embodiment, the thickness of the PI layer is 5μm~15μm.
[0038] Step 3: Prepare at least one copper pillar structure on the first trace.
[0039] Please refer to Figure 4In this embodiment of the invention, the copper pillar structure 101 is still obtained by the sputtering process, photolithography process, electroplating process, and wet process shown in step two. Optionally, the thickness of the photoresist used in this process is different. In this embodiment of the invention, the function of the copper pillar 101 is to connect the first trace 10 and the second trace, so that the first trace 10 and the second trace form mutually perpendicular paths.
[0040] Step four: Cut the carrier board based on the dicing copper wires to obtain the cut structure.
[0041] In this embodiment of the invention, due to technical limitations, it is not possible to directly injection mold a sheet of the same size as the carrier plate. Therefore, please refer to... Figure 5 The carrier plate 11 needs to be cut based on the scribe line 13 to obtain the cut structure. In this embodiment of the invention, the copper pillar structure 101 and the first trace 10 prepared in the aforementioned process are not cut off. In this embodiment of the application, the injection molding material selected for the injection molding layer is epoxy resin, and the filler size can be 25μm, 55μm, or 75μm.
[0042] Step 5: Perform injection molding on the cut structure to obtain the injection-molded layer.
[0043] In this embodiment of the invention, the top surface of the injection-molded layer is flush with the top surface of the copper pillar structure.
[0044] In this embodiment of the invention, injection molding is a commonly used method for plastic encapsulation, used to effectively enhance interlayer bonding and also facilitates the implementation of multilayer wiring on the plastic substrate. After injection molding, as shown... Figure 6 As shown, an injection molding layer 14 is obtained, which covers the carrier plate 11, PI material 12, first wiring 10 and copper pillar structure 101, and the upper surface of the injection molding layer 14 is flush with the top surface of the copper pillar structure 101 for laying the second wiring.
[0045] Step 6: Prepare a second trace on the upper surface of the copper pillar structure. The second trace is a copper circuit.
[0046] In this embodiment of the invention, the fabrication method of the second trace 20 is the same as that of the first trace 10, and will not be described in detail here. For an example, please refer to... Figure 7 The first trace 10 and the second trace 20 have the same wiring structure. In another example, the first trace 10 and the second trace 20 have different wiring structures. The present invention does not limit the correspondence between the first trace 10 and the second trace 20.
[0047] Alternatively, please refer to Figure 7 After the second trace is fabricated, an additional PI layer 21 is coated on the surface of the second trace.
[0048] Step 7: Thin the carrier board and PI layer in the cutting structure to expose the first trace, so as to obtain the injection-molded plastic through-hole encapsulation substrate.
[0049] In the embodiments of the present invention, please refer to Figure 1 The carrier board and PI layer are removed, and the first trace 10 protrudes from the location of the injection molding layer 14. At this time, the first trace 10 is located on the first surface of the substrate, and the second trace 20 is located on the second surface of the substrate. The injection molding layer 14 is combined with the first trace 10 and the second trace 20 to form the substrate.
[0050] In summary, the method provided by the embodiments of the present invention, by flexibly utilizing the dicing process, combines wafer-level redistribution process, wafer-level TMV process and injection molding process, to realize wafer-level injection molding of coreless TMV substrate. Compared with the traditional resin film lamination method, the interlayer bonding strength of the injection molding method will be greatly enhanced, which will help to achieve higher density electrical interconnection.
[0051] In one optional embodiment, the first and second traces are implemented as a single-layer rerouting structure; or, the first and second traces are implemented as a multi-layer rerouting structure.
[0052] In this embodiment of the invention, the bottom of the first trace can be used for flip-chip interconnection with the printed circuit board after ball bonding; the top of the second trace can be exposed through a PI resin photolithography opening for flip-chip interconnection between the functional chip and this substrate. The first and second trace structures can be made into single-layer or multi-layer rewiring structures according to the interconnection functional requirements.
[0053] In an optional embodiment, please refer to Figure 8 The carrier plate 11 is a circular carrier plate, and the arrangement shape of the scribe copper lines 13 is octagonal;
[0054] In one example, step four is implemented as follows: the substrate is cut along the copper wire of the scribe line using a blade to obtain a cut structure. The cut structure is octagonal, and the diameter of the octagon is 5mm smaller than the diameter of the substrate.
[0055] In another example, step four is implemented as follows: the carrier plate is cut by laser reference scribe copper wire to obtain a cut structure. The cut structure is circular, and the diameter of the circle is 5mm smaller than the diameter of the carrier plate.
[0056] In an optional embodiment, step 1 is performed by spin-coating a PI layer onto the upper surface of the carrier and then curing it. In this embodiment, the curing process is performed by baking in an oven. In one example, the drying temperature during the curing process is 230°C, and the drying time is 2 hours.
[0057] In an optional embodiment, step 5 is performed as follows: the cut structure is injection molded to obtain an injection molded body; the injection molded body is ground to expose the upper surface of the copper pillar structure to obtain an injection molded layer.
[0058] In an optional embodiment, the copper pillar structure is a multi-layered copper pillar structure. In this case, when the upper surface of the current layer of copper pillar structure is exposed, a new layer of copper pillar structure is stacked on top of the current layer. When the copper pillar structure stacking is complete, the cut structure is repeatedly diced and injection molded.
[0059] It should be noted that, in the above embodiments, the fabrication processes of the first trace, the second trace, and the copper pillar structure include sputtering, photolithography, electroplating, and wet processing. Specifically, the photoresist used in the photolithography process is Photoresist negative photoresist; in the fabrication processes of the first and second traces, the spin-coating height of the Photoresist negative photoresist is at least 5 μm higher than the first and second trace structures; in the fabrication process of the copper pillar structure, the spin-coating height of the Photoresist negative photoresist is at least 20 μm higher than the copper pillar structure.
[0060] The above are merely optional embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A wafer-level injection molding method for a plastic through-hole encapsulation substrate, characterized in that, The method is applied in the process of preparing a plastic through-hole encapsulation substrate, and the method includes: Step 1: Coat the upper surface of the carrier plate with a polyimide layer; Step 2: Prepare a first trace and a scribe line copper trace on the upper surface of the polyimide layer. The first trace is a copper trace, and the scribe line copper trace is used to define the size of the plastic encapsulation substrate. Step 3: Fabricate at least one copper pillar structure on the first trace; Step 4: Cut the carrier plate based on the dicing copper wire to obtain the cut structure; Step 5: Perform injection molding on the cut structure to obtain an injection-molded layer, the top surface of which is flush with the top surface of the copper pillar structure. Step 6: Prepare a second trace on the upper surface of the copper pillar structure. The second trace is a copper circuit. Step 7: Thin the carrier plate and the polyimide layer in the cutting structure to expose the first trace, so as to obtain the injection-molded plastic through-hole encapsulation substrate.
2. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 1, characterized in that, The first trace and the second trace are implemented as a single-layer rerouting structure; or, the first trace and the second trace are implemented as a multi-layer rerouting structure.
3. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 1, characterized in that, The carrier plate is a circular carrier plate, and the arrangement shape of the copper wires in the scribe line is octagonal; The step of cutting the carrier board based on the scribe line copper wire to obtain the cut structure includes: The carrier plate is cut along the scribe line copper wire by a blade to obtain the cut structure, which is octagonal and the diameter of the octagon is 5mm smaller than the diameter of the carrier plate.
4. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 3, characterized in that, The step of cutting the carrier board based on the scribe line copper wire to obtain the cut structure includes: The carrier plate is cut using a laser as a reference to the scribe line copper wire to obtain the cut structure, which is circular and the diameter of the circle is 5mm smaller than the diameter of the carrier plate.
5. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 1, characterized in that, The process of coating a polyimide layer on the upper surface of the carrier plate includes: A polyimide layer is coated onto the upper surface of the carrier plate by spin coating and then cured.
6. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 1, characterized in that, The injection molding process of the cut structure to obtain an injection-molded layer includes: The cut structure is subjected to injection molding to obtain an injection molded body; The injection-molded body is ground to expose the upper surface of the copper pillar structure, thereby obtaining the injection-molded layer.
7. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 6, characterized in that, The copper pillar structure is a multi-layered copper pillar structure; The method further includes: When the upper surface of the current layer of copper pillar structure is exposed, a new layer of copper pillar structure is stacked on top of the current layer of copper pillar structure; Once the copper pillar structure is stacked, the cut structure is repeatedly diced and injection molded.
8. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 1, characterized in that, The fabrication process of the first trace, the second trace, and the copper pillar structure includes sputtering, photolithography, electroplating, and wet processing.
9. The wafer-level injection molding method for a plastic through-hole encapsulation substrate according to claim 8, characterized in that, The photoresist used in the photolithography process is a negative photoresist; In the fabrication process of the first trace and the second trace, the spin-coating height of the negative photoresist is at least 5 μm higher than the first trace structure and the second trace structure; During the fabrication of the copper pillar structure, the spin-coating height of the negative photoresist is at least 20 μm higher than that of the copper pillar structure.
10. A plastic through-hole encapsulation substrate, characterized in that, The plastic through-hole packaging substrate is prepared by a wafer-level injection molding method as described in any one of claims 1 to 9, and the plastic through-hole packaging substrate includes a first trace, a second trace, and a copper pillar structure. The first trace is located on the first surface of the substrate, and the second trace is located on the second surface of the substrate; The first trace and the second trace are connected through the copper pillar structure; The first trace and the copper pillar structure are encased in an injection molding layer; The second trace is wrapped in a polyimide layer.