A method for manufacturing a buried-copper-block rigid-flex combination board

Abstract

The application discloses a preparation method of a copper block embedded rigid-flex combination board, and comprises the following steps: opening an installation groove at a position corresponding to the installation of a copper block on a core board and a position corresponding to the installation of a copper block on an inter-board prepreg, wherein the inter-board prepreg is a non-flowing prepreg or a low-flowing prepreg; preparing a ring-shaped prepreg, wherein a combination groove matching the shape of the copper block is formed in the middle of the ring-shaped prepreg, and the ring-shaped prepreg is a flowing prepreg; placing the ring-shaped prepreg into the installation groove; stacking the core board and the inter-board prepreg; placing the copper block into the installation groove, and the copper block is located in the combination groove of the ring-shaped prepreg; and high-temperature pressing. The preparation method of the copper block embedded rigid-flex combination board has good combination effect of the copper block and the rigid-flex combination board, and does not cause problems such as cavity, delamination, copper block protrusion or depression.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing, and in particular to a method for preparing a rigid-flex board with embedded copper blocks. Background Technology

[0002] In existing technologies, combining embedded copper block technology with rigid-flex boards can form a composite structure of "embedded copper block + rigid-flex". This composite structure can retain the advantages of rigid-flex boards in irregular installation, dynamic bending and lightweighting, while the embedded copper block can achieve efficient heat dissipation in local high-heat areas, reduce the impact of high temperature on electrical performance, and thus meet the demanding requirements of high-performance servers, power supplies and other equipment with demanding heat dissipation and electrical performance requirements.

[0003] In the traditional manufacturing process of rigid-flex PCBs, windows are typically created in the flexible area of ​​the prepreg (PP), and non-flowing or low-flowing PP is used to prevent adhesive flow that could lead to bonding issues in the flexible area. However, when copper embedding technology is combined with rigid-flex PCBs, and the copper blocks are embedded into the PCB, the bonding strength between the copper blocks and the PCB is insufficient. This can easily lead to problems such as voids, delamination, and protrusions or depressions in the copper blocks and their surroundings, making it difficult to reliably manufacture copper-embedded rigid-flex PCB products. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing a rigid-flexible bonded plate with embedded copper blocks, which achieves good bonding between the copper blocks and the rigid-flexible bonded plate, and avoids problems such as voids, delamination, copper block protrusions or depressions.

[0005] A method for preparing a rigid-flex plate with embedded copper blocks according to an embodiment of the present invention includes the following steps: Mounting slots are made at the locations where the copper blocks are installed on the core board and at the locations where the prepregs are installed between the boards. The prepregs between the boards are either non-flowing or low-flowing. An annular prepreg is prepared, with a bonding groove in the middle of the annular prepreg adapted to the shape of the copper block. The annular prepreg is a flowable prepreg. Place the ring-shaped prepreg into the mounting slot; Stack the core board and the prepreg between the boards; Place the copper block into the mounting groove, where the copper block is located within the bonding groove of the annular prepreg. High temperature lamination.

[0006] According to an embodiment of the present invention, a method for preparing a rigid-flex PCB with embedded copper blocks has at least the following technical effects: After the above-mentioned steps, in the high-temperature pressing step, on the one hand, each core board is fixed by inter-board prepreg, and the inter-board prepreg is a non-flowing or low-flowing prepreg to prevent the prepreg from overflowing and contaminating the flexible area of ​​the rigid-flex PCB. This also meets the high heat resistance requirements of the rigid-flex PCB, ensuring its dimensional and alignment accuracy and preventing structural deformation. On the other hand, in the high-temperature pressing step, the rigid-flex PCB reaches a predetermined temperature. At this temperature, the flowing annular prepreg will flow due to heat. Firstly, this can fill the gaps between the copper block and other components, eliminating any voids that may occur around the copper block. Secondly, it can firmly bond the copper block and the rigid-flex PCB, preventing the copper block from shifting or even coming off, thus preventing the copper block from bulging or sinking later due to movement. Thirdly, it can also fill any gaps that may occur between the inter-board prepreg and the core board due to the mounting groove created by the copper block, preventing voids, delamination, and other problems in the rigid-flex PCB.

[0007] According to some embodiments of the present invention, placing the annular prepreg into the mounting groove includes: Place the ring-shaped prepreg into the mounting slot of the prepreg between the plates.

[0008] According to some embodiments of the present invention, there is a gap between the inner wall of the mounting groove opened on the interplate semi-cured sheet and the outer wall of the annular semi-cured sheet; during high-temperature pressing, the annular semi-cured sheet is heated and flows to fill the gap.

[0009] According to some embodiments of the present invention, no annular prepreg is provided in the mounting groove opened on the core board; after the copper block is placed into the mounting groove, there is a gap between the inner sidewall of the mounting groove opened on the core board and the outer sidewall of the copper block; during high-temperature pressing, the annular prepreg in the mounting groove of the prepreg between the boards is heated and flows to fill the gap.

[0010] According to some embodiments of the present invention, placing the annular prepreg into the mounting groove includes: Place the ring-shaped prepreg into the mounting slot of the core board.

[0011] According to some embodiments of the present invention, there is a gap between the inner wall of the mounting groove opened on the core board and the outer wall of the annular semi-cured sheet; during high-temperature pressing, the annular semi-cured sheet is heated and flows to fill the gap.

[0012] According to some embodiments of the present invention, no annular prepreg is provided in the mounting groove opened on the inter-plate prepreg; after the copper block is placed into the mounting groove, there is a gap between the inner sidewall of the mounting groove opened on the inter-plate prepreg and the outer sidewall of the copper block; during high-temperature pressing, the annular prepreg in the mounting groove of the core board is heated and flows to fill the gap.

[0013] According to some embodiments of the present invention, placing the annular prepreg into the mounting groove includes: Place the annular prepreg into the mounting slots of the core board and the prepreg between the boards.

[0014] According to some embodiments of the present invention, after the copper block is placed into the mounting groove, there is a gap between the inner wall of the mounting groove opened on the core board and the inter-board prepreg and the outer wall of the copper block; during high-temperature pressing, the annular prepreg is heated and flows to fill the gap.

[0015] According to some embodiments of the present invention, after the copper block is placed into the mounting groove, there is a gap between the outer wall of the copper block and the inner wall of the annular prepreg; during high-temperature pressing, the annular prepreg is heated and flows to fill the gap.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the planar structure of the components of a rigid-flexible plate with embedded copper blocks according to an embodiment of the present invention. Figure 2 For the reason Figure 1 The diagram shows the process flow for fabricating the embedded copper block rigid-flex plate. Figure 3 This is a schematic diagram of the cross-sectional structure of a rigid-flexible plate with an embedded copper block, according to another embodiment of the present invention.

[0018] Figure label: Core board 100, inter-board prepreg 200, mounting groove 300, annular prepreg 400, copper block 500. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the orientation descriptions, such as "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "point," "inner," "outer," "axial," "radial," "circumferential," and "around," are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] In the description of this invention, "a plurality of" means two or more; "greater than," "less than," "exceeding," etc., are understood to exclude the number itself; and "above," "below," "within," etc., are understood to include the number itself. Where "first," "second," etc., are used, unless otherwise specified, they are only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0022] In the description of this invention, it should be understood that "A is set on B" or "A is set on B" describes the connection or positional relationship between A and B, and does not mean that A is necessarily above B.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, movable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two components. In some embodiments, "bolted connection" and "screw connection" can be used interchangeably; in some embodiments, sidewall refers to the left sidewall and / or right sidewall. Those skilled in the art can understand the specific meaning of the above terms in this invention in conjunction with the specific circumstances. It should be understood that multiple similar features in this invention are only distinguished by different prefixes. Therefore, in this invention, the feature name without distinguishing prefix (or the feature name with a partial prefix) is used to represent the combination of similar features of this type. For example, "prepreg" is used to represent inter-plate prepreg 200 and annular prepreg 400.

[0024] Reference Figure 1 , Figure 2 and Figure 3 The method for preparing a rigid-flex plate with embedded copper blocks according to an embodiment of the present invention includes the following steps: Mounting grooves 300 are made at the positions where the core board 100 corresponds to the copper block 500 and the positions where the inter-board prepreg 200 corresponds to the copper block 500. The inter-board prepreg 200 is a non-flowing prepreg or a low-flowing prepreg. An annular semi-cured sheet 400 is prepared. The annular semi-cured sheet 400 has a bonding groove in the middle that is adapted to the shape of the copper block 500. The annular semi-cured sheet 400 is a flowable semi-cured sheet. After performing the following steps in any order (or in a predetermined order, in a designed order, etc.), high-temperature pressing is then performed (finally): Place the annular prepreg 400 into the mounting groove 300 (or, stack the annular prepreg 400 on other core boards 100, inter-board prepregs 200, or other components that do not have mounting grooves 300; the same applies to 'placing the copper block 500 into the mounting groove 300' below). Stack the core board 100 and the inter-board prepreg 200; Place the copper block 500 into the mounting groove 300, and the copper block 500 is located in the bonding groove of the annular semi-cured sheet 400.

[0025] The preparation method of the copper-embedded rigid-flex board is referred to as the method. Prepreg, also known as PP sheet, is a key basic material in circuit board manufacturing; non-flowing or low-flowing prepreg is non-flowing PP or low-flowing PP; flowing prepreg is flowing PP. The inter-board prepreg 200 is the prepreg placed between the core boards 100.

[0026] The specific location where the copper block 500 is embedded in the rigid-flex plate can be either embedded inside the rigid-flex plate without being exposed, or exposed (only one end or both ends are exposed). When the copper block 500 is exposed, heat dissipation is more efficient and convenient. It should be understood that "exposed copper block 500" does not mean that the copper block 500 protrudes outward, but rather that one end of the copper block 500 is not blocked by the core board 100 or the prepreg and can directly contact the outside air. In this case, the copper block 500 is still located inside the rigid-flex plate and generally does not protrude outward. The end face of the copper block 500 is flush with or slightly lower than the plate surface. In this embodiment, the copper block 500 penetrates at least one layer of prepreg 200 between the boards. On the one hand, this facilitates the fixing of the copper block 500, allowing it to combine with the prepreg, making the fixing of the copper block 500 more secure and stable. On the other hand, the copper block 500 can contact and connect at least two core boards 100. In particular, in some embodiments, the exposed copper block 500 connects to the inner core board 100, thereby conducting the heat of the inner core board 100 to the outside (or to the outer core board 100 or its heat dissipation structure), facilitating heat dissipation. The end of the copper block 500 can be on the prepreg, allowing the end of the copper block 500 and the prepreg to be combined to a certain extent, properly fixing the copper block 500, and appropriately buffering and absorbing the pressing force transmitted by the copper block 500 during pressing, preventing the core board 100 from being squeezed; or it can be on the core board 100 (in which case a certain pressing gap can be reserved between the core board 100 and the end of the copper block 500, and certain anti-conductive treatment can be done, such as placing a layer of thermally conductive prepreg between the core board 100 and the end of the copper block 500), with a large contact area with the core board 100, facilitating heat conduction and dissipation, and also allowing the core board 100 to support the copper block 500 to a certain extent after the circuit board is formed, preventing the copper block 500 from sinking; the specific design needs to be determined according to the actual situation. It should be understood that, further, in some embodiments, a layer of flowable semi-cured sheet may also be provided at the end of the copper block 500. This layer of flowable semi-cured sheet covers the bottom of the mounting groove 300 (core board 100 or inter-board semi-cured sheet 200), so that the copper block 500 and the rigid-flex plate can be bonded more firmly.

[0027] The shapes of the mounting groove 300, the annular prepreg 400, and the mating groove are all related to (or compatible with, similar to) the shape of the copper block 500. However, since the copper block 500 needs to penetrate the core board 100, the inter-board prepreg 200, and even multiple core boards 100 and inter-board prepregs 200, the shapes of the copper blocks 500 corresponding to each core board 100 and inter-board prepreg 200, and even between each individual core board 100 and inter-board prepreg 200, may differ. In other words, during the design phase, the copper block... The structure is divided into multiple layers, with each copper block 500 corresponding to a core board 100 or an inter-board prepreg 200. The core board 100 or inter-board prepreg 200 has mounting grooves 300 corresponding to the shape of the copper block 500 (or annular prepreg 400). Similarly, when multiple annular prepregs 400 are provided (or in multiple layers), each copper block 500 corresponds to an annular prepreg 400, and the annular prepreg 400 has a mating groove corresponding to its shape. The specific shape of the annular prepreg 400 is not limited but must be designed according to the shape of the corresponding copper block 500 (i.e., "fitting the shape of the copper block 500"). Therefore, the specific shape of the annular prepreg 400 is not limited to common circular or square rings. Likewise, the specific ring width of the annular prepreg 400 can be set according to actual conditions, and the ring width of each area of ​​the annular prepreg 400 does not necessarily need to be the same everywhere; it can be adjusted according to actual conditions. It is important to understand that the number of annular prepreg sheets 400 can be one or more; multiple annular prepreg sheets 400 can be placed in the same mounting groove 300 of the core board 100 or the inter-board prepreg sheet 200, or they can be placed in different mounting grooves 300 of the core board 100 or the inter-board prepreg sheet 200; or the arrangement of multiple annular prepreg sheets 400 can be a combination of the above two. It is also important to understand that the thickness of the annular prepreg sheet 400 can be adjusted according to the actual situation. Specifically, when the depth of a mounting groove 300 is shallow, the thickness of the annular prepreg sheet 400 may need to be appropriately reduced to fit the mounting groove 300; while when the depth of a mounting groove 300 is deep, multiple annular prepreg sheets 400 may need to be stacked in the mounting groove 300, and the thickness of at least one annular prepreg sheet 400 may need to be appropriately adjusted. It should be understood that the prepreg of the present invention, particularly the annular prepreg 400, can be a prepreg with good thermal conductivity, facilitating heat conduction, especially heat conduction to the copper block 500 for heat dissipation. It should also be understood that the mounting groove 300 is generally a through groove, but in some special embodiments, the innermost mounting groove 300 may not be a through groove and may have a groove bottom structure. The core board 100 and the inter-board prepreg 200 are stacked sequentially vertically, with the surfaces of the core board 100 and the inter-board prepreg 200 approximately parallel to the horizontal plane.It should be understood that the high temperature in the "high-temperature pressing" step is the temperature at which the flowable annular prepreg 400 is softened (or melted) and made to flow due to heat. This temperature is well known to those skilled in the art (or can be directly obtained from the instruction manual of the annular prepreg 400). At this temperature, the non-flowable, low-flow inter-plate prepreg 200 does not flow (or does not flow significantly), but only bonds other components. Therefore, those skilled in the art determine the specific value of this temperature based on the actual situation.

[0028] It should be understood that the order in which the steps are written in the method of this invention does not absolutely determine the order of the actions. A step written later in the order of the steps may be performed earlier or simultaneously with other steps in some embodiments. For example, in the above method, the execution order of 'processing the annular prepreg 400' and 'processing the mounting groove 300 on the core board 100 and the inter-board prepreg 200' is not absolutely sequential. Similarly, 'placing the annular prepreg 400 into the mounting groove 300' and 'stacking the core board 100 and the inter-board prepreg 200' are also related. The execution order of these two steps can be selected according to the actual situation, and the two steps can also be repeated. In particular, for solutions where it is not easy to place the copper block 500 into the rigid-flex plate, such as when there are large differences between the layers of the copper block 500 (the copper block 500 is an irregular shape), the copper block 500 can be kept stationary, and the annular prepreg 400, core board 100, inter-board prepreg 200, etc. can be placed on the copper block 500. This can also achieve the results of 'placing the copper block 500 into the mounting groove 300' and 'placing the annular prepreg 400 into the mounting groove 300'.

[0029] After the above steps, in the high-temperature pressing step, on the one hand, each core board 100 is bonded and fixed by the inter-board semi-cured sheet 200, and the inter-board semi-cured sheet 200 is a non-flowing semi-cured sheet or a low-flowing semi-cured sheet to prevent the semi-cured sheet from flowing out and contaminating the flexible area of ​​the rigid-flex bonded board, and can meet the high heat resistance requirements of the rigid-flex bonded board, ensure its dimensional accuracy and alignment accuracy, and avoid structural deformation. On the other hand, during the high-temperature pressing step, the rigid-flex PCB reaches a predetermined temperature (or a predetermined temperature is applied to the rigid-flex PCB). At this temperature, the flowable annular prepreg 400 will flow (or melt and flow) due to heat. Firstly, it can fill the gaps between the copper block 500 and other components (annular prepreg 400, inter-plate prepreg 200, and core plate 100), eliminating any voids that may occur around the copper block 500. Secondly, it can firmly bond the copper block 500 to the rigid-flex PCB, preventing the copper block 500 from shifting or even coming off, so that the copper block 500 will not bulge or dent due to movement later. Thirdly, it can also fill any gaps that may occur between the inter-plate prepreg 200 and the core plate 100 caused by the mounting groove 300 created by the copper block 500, preventing voids, delamination, and other problems in the rigid-flex PCB.

[0030] It's important to understand that other processing techniques for the embedded copper block rigid-flex board can be carried out using conventional methods in existing technologies. For example, a window can be made on the prepreg 200 corresponding to the flexible area of ​​the core board 100, removing most (but not all) of the PP in that area (the rigid scrap area can be retained and removed later). Alternatively, the inner flexible core board 100 can be manufactured using conventional methods, including material preparation, circuit fabrication, laser milling, browning, etc. The outermost rigid core board 100 can be similarly processed. It's also important to understand that after the copper blocks 500 are installed but before lamination, the core board 100 and the prepreg 200 can still be stacked, and even other copper blocks 500 can be embedded. In other words, the above methods are merely a basic framework for manufacturing embedded copper block rigid-flex boards, and further expansion can be made based on specific needs. It should be understood that, furthermore, the copper block 500 can be browned before being placed into the mounting slot 300, thereby increasing the bonding force between the copper block 500 and the prepreg, making the copper block 500 more securely and stably fixed.

[0031] In some embodiments, the annular prepreg 400 is only disposed in the mounting groove 300 of the inter-plate prepreg 200, and not disposed in the mounting groove 300 of the core plate 100. In this case, the gap between the inner sidewall of the mounting groove 300 of the core plate 100 and the outer sidewall of the copper block 500 is small (separated by a second predetermined distance). After high-temperature pressing, the annular prepreg 400 in other positions is heated and flows to fill the gap between the inner sidewall of the mounting groove 300 of the core plate 100 and the outer sidewall of the copper block 500.

[0032] In some embodiments, the annular semi-cured sheet 400 is not only disposed in the mounting groove 300 of the inter-plate semi-cured sheet 200, but also disposed in the mounting groove 300 of the core board 100.

[0033] In some embodiments, the annular prepreg 400 is only disposed in the mounting groove 300 of the core board 100, and not disposed in the mounting groove 300 of the inter-board prepreg 200. In this case, the gap between the inner sidewall of the mounting groove 300 of the inter-board prepreg 200 and the outer sidewall of the copper block 500 is small (a fifth predetermined distance apart). After high-temperature pressing, the annular prepreg 400 in other positions is heated and flows to fill the gap between the inner sidewall of the mounting groove 300 of the inter-board prepreg 200 and the outer sidewall of the copper block 500.

[0034] In some embodiments, at least one core board 100 has an annular semi-cured sheet 400 in its mounting groove 300, while at least another core board 100 does not have an annular semi-cured sheet 400 in its mounting groove 300. The gap between the inner wall of the mounting groove 300 of the core board 100 without the annular semi-cured sheet 400 and the outer wall of the copper block 500 is smaller (separated by a second predetermined distance). After high-temperature pressing, the gap between the inner wall of the mounting groove 300 of the core board 100 and the outer wall of the copper block 500 is filled by the annular semi-cured sheets 400 in other locations after being heated and flowing.

[0035] In some embodiments, at least one inter-plate prepreg 200 has an annular prepreg 400 in its mounting groove 300, while at least another inter-plate prepreg 200 does not have an annular prepreg 400 in its mounting groove 300. The gap between the inner wall of the mounting groove 300 of the inter-plate prepreg 200 without an annular prepreg 400 and the outer wall of the copper block 500 is smaller (a fifth predetermined distance apart). After high-temperature pressing, the gap between the inner wall of the mounting groove 300 of the inter-plate prepreg 200 and the outer wall of the copper block 500 is filled by the heated flow of the annular prepreg 400 in other locations.

[0036] Reference Figure 1 , Figure 2 and Figure 3In some embodiments of the present invention, placing the annular prepreg 400 into the mounting groove 300 includes: Place the annular prepreg 400 into the mounting groove 300 of the interplate prepreg 200.

[0037] Alternatively, after the annular prepreg 400 is placed into the mounting groove 300, the annular prepreg 400 is located within the mounting groove 300 of the inter-plate prepreg 200.

[0038] The annular prepreg 400 is located within the mounting groove 300 of the inter-plate prepreg 200. During high-temperature pressing, the annular prepreg 400, after being heated and flowing, primarily fills the gap between the inner wall of the mounting groove 300 of the inter-plate prepreg 200 and the outer wall of the copper block 500, and can also bond the copper block 500 and the inter-plate prepreg 200 together. Since both the annular prepreg 400 and the inter-plate prepreg 200 are prepregs, their bonding is more robust, allowing the copper block 500 to be fixed more quickly and firmly, and preventing it from easily detaching during use.

[0039] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, there is a gap (or, a predetermined gap, an installation gap; the same applies below) between the inner wall of the mounting groove 300 opened on the interplate semi-cured sheet 200 and the outer wall of the annular semi-cured sheet 400; during high-temperature pressing, the annular semi-cured sheet 400 is heated and flows to fill the gap.

[0040] Alternatively, the inner wall of the mounting groove 300 on the prepreg 200 and the outer wall of the annular prepreg 400 are separated by a first predetermined distance.

[0041] A certain gap is left between the prepreg 200 and the annular prepreg 400 to facilitate the placement (or installation, stacking) of the annular prepreg 400. The gap is very small, allowing the annular prepreg 400 to flow and fill the gap during high-temperature pressing, minimizing the formation of voids. In this embodiment, the first predetermined distance is 0.05mm-0.1mm; all predetermined distances (or intervals) described in this invention refer to horizontal distances (intervals).

[0042] In some embodiments, there may be no gap between the inner wall of the mounting groove 300 on the inter-plate semi-cured sheet 200 and the outer wall of the annular semi-cured sheet 400, or in other words, the inter-plate semi-cured sheet 200 and the annular semi-cured sheet 400 are interference-fitted together.

[0043] Reference Figure 1 , Figure 2 and Figure 3In some embodiments of the present invention, the mounting groove 300 on the core board 100 is not provided with an annular semi-cured sheet 400; after the copper block 500 is placed into the mounting groove 300, there is a gap between the inner sidewall of the mounting groove 300 on the core board 100 and the outer sidewall of the copper block 500; during high-temperature pressing, the annular semi-cured sheet 400 in the mounting groove 300 of the inter-board semi-cured sheet 200 is heated and flows to fill the gap.

[0044] Alternatively, the mounting groove 300 on the core board 100 is not provided with an annular semi-cured sheet 400; after the copper block 500 is placed into the mounting groove 300, the inner sidewall of the mounting groove 300 on the core board 100 and the outer sidewall of the copper block 500 are separated by a second predetermined distance.

[0045] The mounting groove 300 on the core board 100 does not contain an annular prepreg 400. The gap between the inner wall of the mounting groove 300 and the outer wall of the copper block 500 is filled by annular prepregs 400 in other locations (such as those in the mounting grooves 300 of adjacent prepregs 200 on the core board 100) after high-temperature pressing, which then flow and fill the gap. This arrangement minimizes the distance between the core board 100 and the copper block 500, facilitating easier heat transfer from the core board 100 to the copper block 500, resulting in more efficient heat dissipation. It should be understood that the annular prepreg 400 can be a prepreg with good thermal conductivity, ensuring basic high-temperature flow and filling functions while also facilitating heat transfer to the copper block 500 after connecting it to other components. In this embodiment, the second predetermined distance is 0.05mm-0.1mm.

[0046] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, placing the annular prepreg 400 into the mounting groove 300 includes: Place the annular semi-cured sheet 400 into the mounting groove 300 of the core board 100.

[0047] Alternatively, after the annular prepreg 400 is placed into the mounting groove 300, the annular prepreg 400 is located in the mounting groove 300 of the core board 100.

[0048] The annular prepreg 400 is located within the mounting groove 300 of the core board 100. During high-temperature pressing, the annular prepreg 400, after being heated and flowing, primarily fills the gap between the inner wall of the mounting groove 300 of the core board 100 and the outer wall of the copper block 500, and can also bond the copper block 500 and the core board 100 together. This design ensures that the prepreg can fill the gap between the inner wall of the mounting groove 300 of the core board 100 and the outer wall of the copper block 500 as much as possible after high-temperature pressing, avoiding the formation of voids. Voids are prone to retaining corrosive substances, and air has low heat transfer efficiency; therefore, the presence of voids will have a certain impact on heat conduction.

[0049] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, there is a gap between the inner wall of the mounting groove 300 on the core board 100 and the outer wall of the annular semi-cured sheet 400; during high-temperature pressing, the annular semi-cured sheet 400 is heated and flows to fill the gap.

[0050] Alternatively, there is a third predetermined distance between the inner wall of the mounting groove 300 on the core board 100 and the outer wall of the annular semi-cured sheet 400.

[0051] A certain gap is left between the core board 100 and the annular prepreg 400 to facilitate the placement (or installation, stacking) of the annular prepreg 400. The gap is very small, allowing the annular prepreg 400 to flow and fill the gap during high-temperature pressing, minimizing the formation of voids. In this embodiment, the third predetermined distance is 0.05mm-0.1mm.

[0052] In some embodiments, there may be no gap between the inner wall of the mounting groove 300 on the core plate 100 and the outer wall of the annular semi-cured sheet 400, or the core plate 100 and the annular semi-cured sheet 400 may be connected by an interference fit.

[0053] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, no annular prepreg 400 is provided in the mounting groove 300 opened on the inter-plate prepreg 200; after the copper block 500 is placed into the mounting groove 300, there is a gap between the inner sidewall of the mounting groove 300 opened on the inter-plate prepreg 200 and the outer sidewall of the copper block 500; during high-temperature pressing, the annular prepreg 400 in the mounting groove 300 of the core board 100 is heated and flows to fill the gap.

[0054] Alternatively, the annular prepreg 400 may be placed only in the mounting groove 300 of the core board 100, but not in the mounting groove 300 of the inter-board prepreg 200.

[0055] No annular prepreg 400 is provided in the mounting groove 300 opened on the inter-plate prepreg 200. The gap between the inner side wall of the mounting groove 300 opened on the inter-plate prepreg 200 and the outer side wall of the copper block 500 is filled by the annular prepreg 400 in other positions (such as the annular prepreg 400 in the mounting groove 300 of the core board 100 adjacent to the inter-plate prepreg 200) after being heated and flowing.

[0056] With this configuration, after the copper block 500 is placed into the mounting groove 300, there is generally no gap between the inner wall of the mounting groove 300 on the prepreg 200 and the outer wall of the copper block 500. During high-temperature pressing, the prepreg 200 and the copper block 500 are mainly bonded together, especially when the prepreg 200 is a low-flow type prepreg. Furthermore, the prepreg 200 has good deformability, facilitating an interference fit connection with the copper block 500. In other embodiments, after the copper block 500 is placed into the mounting groove 300, the inner wall of the mounting groove 300 on the prepreg 200 and the outer wall of the copper block 500 are separated by a fifth predetermined distance; this fifth predetermined distance can be 0.05mm-0.1mm.

[0057] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, placing the annular prepreg 400 into the mounting groove 300 includes: The annular prepreg 400 is placed into the mounting groove 300 of the core board 100 and the inter-board prepreg 200.

[0058] Alternatively, the annular prepreg 400 can be set (placed) in the mounting groove 300 of the core board 100 or in the mounting groove 300 of the prepreg 200.

[0059] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, after the copper block 500 is placed into the mounting groove 300, there is a gap between the inner sidewall of the mounting groove 300 on the core plate 100 and the outer sidewall of the copper block 500; during high-temperature pressing, the annular semi-cured sheet 400 is heated and flows to fill the gap.

[0060] Alternatively, after the copper block 500 is placed into the mounting groove 300, the inner wall of the mounting groove 300 on the core board 100 and the outer wall of the copper block 500 are separated by a second predetermined distance, and the inner wall of the mounting groove 300 on the prepreg 200 is separated by a fifth predetermined distance; both the second and fifth predetermined distances can be 0.05mm-0.1mm.

[0061] Referring to the above embodiments, the specific placement of the annular prepreg 400 needs to be selected according to the actual situation.

[0062] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, after the copper block 500 is placed into the mounting groove 300, there is a gap between the outer side wall of the copper block 500 and the inner side wall of the annular semi-cured sheet 400; during high-temperature pressing, the annular semi-cured sheet 400 is heated and flows to fill the gap.

[0063] Alternatively, after the copper block 500 is placed into the mounting groove 300, there is a fourth predetermined distance between the outer wall of the copper block 500 and the inner wall (side wall of the mounting groove) of the annular semi-cured sheet 400.

[0064] A certain gap is left between the copper block 500 and the annular prepreg 400 to facilitate the placement (or installation, stacking) of the copper block 500. The gap is very small, allowing the annular prepreg 400 to flow and fill the gap during high-temperature pressing, minimizing the formation of voids. In this embodiment, the fourth predetermined distance is 0.05mm-0.1mm.

[0065] In some embodiments, after the copper block 500 is placed into the mounting groove 300, there may be no gap between the outer side wall of the copper block 500 and the inner side wall (side wall of the connecting groove) of the annular semi-cured sheet 400, or in other words, the copper block 500 and the annular semi-cured sheet 400 are interference-fitted together.

[0066] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, multiple core boards 100 are provided, and when the core boards 100 and the inter-board prepreg 200 are stacked, the inter-board prepreg 200 is placed between any two adjacent core boards 100.

[0067] Multiple core plates 100 are provided, including rigid core plates 100 and flexible core plates 100, which facilitates the formation of a rigid-flexible bonded plate after pressing; and further, multiple rigid core plates 100 and / or flexible core plates 100 can also be provided.

[0068] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, at least one of the plurality of core boards 100 is provided with a mounting groove 300, and the core board 100 provided with the mounting groove 300 is located on the outermost layer, inner layer, or both inside and outside of the stacked core boards 100 and the inter-board prepreg 200.

[0069] The copper block 500 can conduct heat to only one core board 100, or it can conduct heat to multiple core boards 100; alternatively, multiple copper blocks 500 can be provided, each conducting heat to one or more core boards 100. "Both inside and outside" means that the core board 100 with the mounting groove 300 is located on the outermost layer of the stacked core boards 100 and the inter-board prepreg 200, and also on the inner layer of the stacked core boards 100 and the inter-board prepreg 200; or, in other words, both the outermost and inner layers of the stacked core boards 100 and the inter-board prepreg 200 have the mounting groove 300; or, in other words, both the outermost and innermost core boards 100 in the stacked core boards 100 and the inter-board prepreg 200 have the mounting groove 300.

[0070] Reference Figure 1 , Figure 2 and Figure 3 In some embodiments of the present invention, the core board 100 includes a rigid core board 100 and a flexible core board 100. The rigid core board 100 is located on the outermost layer of the stacked core board 100 and the inter-board prepreg 200, and the flexible core board 100 is located on the inner layer of the stacked core board 100 and the inter-board prepreg 200.

[0071] The rigid core board 100 is the outermost layer, with high load-bearing capacity and good mechanical strength, facilitating contact and connection with external objects. The flexible core board 100 is the inner layer, which can be bent and folded, facilitating irregular installation and dynamic bending.

[0072] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for manufacturing a build-up copper bump BGA board, characterized in that, Includes the following steps: Mounting slots are made at the locations where the copper blocks are installed on the core board and at the locations where the prepregs are installed between the boards. The prepregs between the boards are either non-flowing or low-flowing. An annular prepreg is prepared, with a bonding groove in the middle of the annular prepreg adapted to the shape of the copper block. The annular prepreg is a flowable prepreg. Place the ring-shaped prepreg into the mounting slot; Stack the core board and the prepreg between the boards; Place the copper block into the mounting groove, where the copper block is located within the bonding groove of the annular prepreg. High temperature lamination.

2. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 1, characterized in that, The step of placing the annular semi-cured sheet into the mounting groove includes: Place the ring-shaped prepreg into the mounting slot of the prepreg between the plates.

3. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 2, characterized in that, There is a gap between the inner wall of the mounting groove on the prepreg and the outer wall of the annular prepreg; during high-temperature pressing, the annular prepreg is heated and flows to fill the gap.

4. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 2, characterized in that, No annular prepreg is provided in the mounting groove on the core board; after the copper block is placed into the mounting groove, there is a gap between the inner sidewall of the mounting groove on the core board and the outer sidewall of the copper block; during high-temperature pressing, the annular prepreg in the mounting groove of the prepreg between the boards flows due to heat and fills the gap.

5. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 1, characterized in that, The step of placing the annular semi-cured sheet into the mounting groove includes: Place the ring-shaped prepreg into the mounting slot of the core board.

6. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 5, characterized in that, There is a gap between the inner wall of the mounting groove on the core board and the outer wall of the annular semi-cured sheet; during high-temperature pressing, the annular semi-cured sheet is heated and flows to fill the gap.

7. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 5, characterized in that, No annular prepreg is provided in the mounting groove on the prepreg between the boards; after the copper block is placed into the mounting groove, there is a gap between the inner sidewall of the mounting groove on the prepreg between the boards and the outer sidewall of the copper block; during high-temperature pressing, the annular prepreg in the mounting groove of the core board is heated and flows to fill the gap.

8. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 1, characterized in that, The step of placing the annular semi-cured sheet into the mounting groove includes: Place the annular prepreg into the mounting slots of the core board and the prepreg between the boards.

9. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 8, characterized in that, After the copper block is placed into the mounting groove, there is a gap between the inner wall of the mounting groove on the core board and the outer wall of the copper block; during high-temperature pressing, the annular prepreg is heated and flows to fill the gap.

10. The method for preparing a rigid-flexible plate with embedded copper blocks according to claim 1, characterized in that, After the copper block is placed into the mounting groove, there is a gap between the outer wall of the copper block and the inner wall of the annular prepreg; during high-temperature pressing, the annular prepreg is heated and flows to fill the gap.

Images