A PCB board with stepped multi-chip stacking connection

Abstract

The present invention discloses a PCB board with stepped multi-chip stacking connection, comprising a PCB board and a chip, a recessed first step being provided on the PCB board, the area exposed by the chip opening on the first step being subjected to primary processing protection and secondary processing protection in sequence, a second step being provided on the PCB board, the second step being arranged adjacent to the first step in a stepped manner, the first step and the second step after the secondary processing protection being provided by a gong PP window setting, the areas exposed by the chip opening on the first step and the second step being pressed together by corresponding undercut convex molds, so that the upper surfaces of the undercut convex molds on the first step and the second step are flush, and after pressing together, the outer layer of the PCB board is subjected to solder mask treatment and cleaning. The chip sinks into the PCB board, and the multi-layer chips are arranged in a sunken and stepped manner, which not only reduces the overall thickness and can be developed in an ultra-thin direction, but also shortens the signal transmission distance to the connection distance between the chip and the inner layer circuit of the PCB, thereby accelerating the transportation and processing capabilities.

Description

Technical Field

[0001] The present invention belongs to the technical field of PCB board manufacturing, and in particular relates to a PCB board with stepped multi-chip stacking connections. Background Art

[0002] PCB board is the abbreviation of circuit board, which is the control core of all products and equipment that need to be controlled.

[0003] The problem with existing circuit boards is that chips are generally mounted on PCBs. As a result, the overall thickness is the sum of the chip thickness and the PCB thickness. For multi-chip stacks, the overall thickness is the combined thickness of the PCB and all the chips. This results in a relatively large overall PCB thickness, preventing the product from developing in the direction of ultra-thinness. This is especially true for today's miniaturization requirements, which cannot be met by traditional manufacturing methods. Furthermore, such PCBs have long transmission distances, resulting in slow processing capabilities.

[0004] Secondly, for the existing patent with application number 201410033506.2, a method for manufacturing a WB-type packaging substrate is specifically disclosed, including: manufacturing a step unit with a wire bonding pad; attaching a composite dry film layer on the surface of the step unit with the wire bonding pad, and then performing pattern transfer on the composite dry film layer to form a patterned composite dry film layer on the surface of the step unit with the wire bonding pad; milling and grooving the semi-cured sheet to form a window in the semi-cured sheet, and positioning and laminating the semi-cured sheet after milling and grooving, the step unit with the dry film formed, and the top plate together; executing the outer layer PCB manufacturing process; performing through-groove milling and controlled-depth milling from the top plate to expose the composite dry film layer of the step unit; removing the composite dry film layer to expose the wire bonding pad; and performing finished product milling after the wire bonding pad is exposed. Among them, the method of through-groove milling and controlled-depth milling followed by pressing is not feasible, because it will cause the membrane surface to sink toward the middle during pressing, leading to a serious problem of glue overflowing toward the middle. Summary of the Invention

[0005] The object of the present invention is to provide a PCB board with stepped multi-chip stacking connections to solve the problems raised in the above background technology.

[0006] In view of this, the present invention provides a PCB board with stepped multi-chip stacking connection, comprising a PCB board and a chip, a recessed first-level step being provided on the PCB board, the first-level step and the chip being bonded with a PAD, so that the chip is mounted on the first-level step and connected to the PAD through a bonding line, and the area exposed by the chip window on the first-level step is subjected to primary processing protection and secondary processing protection in sequence, a second-level step being provided on the PCB board, the second-level step and the first-level step being arranged adjacent to the first-level step in a stepped manner, the second-level step being bonded to the PAD, the chip being mounted on the second-level step and the chip being connected to the PAD on the second-level step through a bonding line, and the area exposed by the chip window on the second-level step being subjected to primary processing protection and secondary processing protection in sequence, the first-level step and the second-level step after the secondary processing protection being provided with a window through a gong PP, and the areas exposed by the chip window on the first-level step and the second-level step being pressed together by corresponding inverted convex molds, so that the upper surfaces of the inverted convex molds on the first-level step and the second-level step are flush, and after pressing together, the outer layer of the PCB board is subjected to solder mask treatment and cleaned.

[0007] In the present invention, further, the first-level step and the second-level step are arranged in a stepped manner, and the first-level step is located below the horizontal plane of the second-level step, and is arranged on a stepped network according to the number of steps.

[0008] In the present invention, further, the first-level step and the second-level step are milled out by a CNC machine tool.

[0009] In the present invention, further, the one-time protection treatment is sequentially performed by printing anti-plating ink, exposing, developing and UV treatment according to the areas of the chip exposed by the window openings on the first step and the second step, wherein the liquid photosensitive anti-plating ink is evenly covered on the surface of the first step and the second step by one of screen printing, spraying or curtain coating, and then pre-baked at 70°C-100°C to form a dry film layer, and then the ink is selectively exposed through a mask using ultraviolet light, and the ultraviolet light uses a g-line (436nm) wavelength light source, and then the unexposed part of the ink is dissolved by an alkaline developer to expose the substrate area to be plated, and finally the UV treatment uses a cold light source UV LED device (power 80W / cm).

[0010] In the present invention, further, the secondary processing protection is to affix a high-temperature PI protective film on the first step and the second step of the chip, and then laser cut the pattern to expose the chip window area.

[0011] In the present invention, further, the laser PP windowing includes laser windowing in the areas where windowing is required on the first-step and second-step chips. The windowing area on the PP film is larger than the exposed size of the chip, and the single side of the window on the PP film is 10 mil away from the single side size of the chip.

[0012] In the present invention, further, the inverted convex mold includes an integrally formed base plate and a punch, the size of the punch is smaller than the size of the base plate, the shape of the punch is consistent with the area where the chip window is exposed on the first step and the second step, and the punch is embedded in the area where the chip window is exposed, so that the upper surface of the base plate of the inverted convex mold on the first step and the second step is located on the same horizontal plane.

[0013] In the present invention, further, after lamination, the first step and the second step are wrapped with a protective film and subjected to an outer layer solder resist treatment of the PCB board.

[0014] In the present invention, further, after the solder resist treatment, the protective film and the inverted convex mold are removed, and a high-temperature PI protective film is affixed.

[0015] In the present invention, laser and plasma are further used to clean the PCB board.

[0016] The beneficial effects of the present invention are:

[0017] This stepped multi-chip stacked PCB board uses a stepped mounting connection method to make a PCB board. According to the number of chips to be stacked, a corresponding number of steps are opened. The steps are arranged in a stepped manner. The PAD and the mounted chips are bonded on the corresponding steps to connect the bonding lines. The first and second steps are sequentially processed for protection and the second step for protection. Windowing is performed according to the area where the chip needs to be exposed. The above production steps are repeated according to the number of chip layers. After completion, PP processing is performed on the first and second steps, and windowing is performed on the area where the chip needs to be exposed. , and then design the inverted convex mold corresponding to each step to fit on each chip, so that the upper surface of the inverted convex mold on each step is in the same horizontal plane state before pressing, avoiding the overflow of glue caused by the PP film sinking to the middle during pressing, maintaining the uniformity of pressing, and finally performing solder mask and foreign matter cleaning to complete the production. Through this method, the chip is sunk into the PCB board, and the multi-layer chips are arranged and connected in a sunken and stepped manner, which not only reduces the overall thickness and can develop in the direction of ultra-thinness, but also shortens the signal transmission distance to the connection distance between the chip and the inner layer circuit of the PCB, thereby speeding up the transportation and processing capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a PCB board of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0020] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items below.

[0021] It should be noted that the terms "first," "second," etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way are interchangeable where appropriate, so that the embodiments of this application can be implemented in an order other than those illustrated or described herein, and that the objects distinguished by "first," "second," etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0022] It should be noted that, in the description of this application, the directions indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of this application; the directional terms "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0023] It should be noted that, in the present application, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0024] This embodiment provides a PCB board with a stepped multi-chip stack connection, including a PCB board 1 and a chip 2. The chip 2 can be multiple pieces, and is designed to be mounted in a form of sinking inside the PCB board 1 so that the overall thickness does not exceed the thickness of the PCB board 1.

[0025] In this embodiment, specifically, first, a recessed first-level step 10 is provided on the PCB board 1. The first-level step 10 can be milled by CNC milling or laser milling, and this embodiment does not impose any specific restrictions. The first-level step 10 and the chip 2 are both bonded with PADs, so that the chip 2 is mounted on the first-level step 10 and connected to the PADs through bonding wires. The PADs (solder pads) are key structures for achieving electrical connection and mechanical fixation between electronic components and circuit boards.

[0026] Secondly, the area exposed by the window of the chip 2 on the first step 10 is subjected to primary protection and secondary protection in sequence;

[0027] Specifically, the primary protection process sequentially performs resist plating ink printing, exposure, development, and UV treatment based on the area of ​​the chip 2 exposed by the window on the first step 10. The area of ​​the chip 2 exposed by the window means the area of ​​the chip 2 exposed on the first step 10. This area cannot be blocked in subsequent processes, that is, the chip 2 must be exposed.

[0028] Subsequently, a liquid photosensitive anti-plating ink is uniformly coated on the surface of the first step 10 by screen printing, spraying or curtain coating, and then pre-baked at 70° C.-100° C. to form a dry film layer to avoid over-curing that affects development. The anti-plating ink can be composed of acrylic epoxy resin, thermosetting epoxy resin, reactive diluent and photoinitiator.

[0029] The ink is then selectively exposed to ultraviolet light through a mask using a g-line (436nm) wavelength light source. An alkaline developer then dissolves the unexposed ink, revealing the substrate area to be plated. Finally, a cold light source UV LED device (80W / cm2) is used for UV treatment. After UV treatment, the ink is completely cross-linked at high temperatures (approximately 150°C) to enhance its resistance to plating solutions and mechanical strength.

[0030] Then, a secondary step 11 is opened on the PCB board 1, and the secondary step 11 and the primary step 10 are arranged adjacent to each other in a stepped manner. The secondary step 11 is bonded to the PAD, and the chip 2 is mounted on the secondary step 11 and the chip 2 is connected to the PAD on the secondary step 11 through a bonding line. The area of ​​the chip 2 exposed by the window on the secondary step 11 is subjected to primary processing protection and secondary processing protection in sequence. After the secondary processing protection, the primary step 10 and the secondary step 11 are set with a gong PP window, and the corresponding inverted convex mold 3 is used to press the area of ​​the chip 2 exposed by the window on the primary step 10 and the secondary step 11, so that the upper surface of the inverted convex mold 3 on the primary step 10 and the secondary step 11 is flush. After pressing, the outer layer of the PCB board 1 is solder-resistant and cleaned.

[0031] After the first protection treatment, a second protection treatment is performed. The second protection treatment is to stick a high-temperature PI protective film on the first step 10 of the chip 2. After laser cutting, the pattern is exposed in the window area of ​​the chip 2. The PI film (polyimide film) is a high-performance polymer material. It is made by polycondensing pyromellitic dianhydride (PMDA) and diaminodiphenyl ether (ODA / DDE) in a strong polar solvent, casting into a film, and then imidizing. It is an existing film.

[0032] Then, the secondary step 11 is fabricated according to the above steps, and the above method is repeated for chip 2 placement, primary processing and protection, and secondary processing and protection on the secondary step 11. It should be noted that the primary step 10 and the secondary step 11 are arranged in a stepped manner, with the primary step 10 located below the horizontal plane of the secondary step 11. The number of steps is determined by the number of paper chips 2 required.

[0033] In this embodiment, a further step is to perform laser PP windowing on the first-level step 10 and the second-level step 11. The laser PP windowing includes laser windowing in the areas where windowing is required on the first-level step 10 and the second-level step 11 chip 2. The windowing area on the PP film is larger than the exposed size of the chip 2. The single side of the windowing on the PP film is 10 mil away from the single side size of the chip 2. The reason for this setting is that under high temperature of lamination, it will flow to fill the gap in the core board. A slightly larger windowing area can reserve space for the resin flow during lamination to avoid resin overflow to the chip 2 area, resulting in local uneven thickness or impedance deviation. The expansion of the windowing area can provide a buffer zone to reduce stress concentration during temperature changes or mechanical bending, and avoid delamination or fracture. The expansion of the PP windowing can ensure that the solder mask layer is aligned with the PP window to avoid the solder mask ink covering the chip 2 pad. If the windowing is too small, the edge PP will remain, which may cause local impedance discontinuity and affect the integrity of the high-speed signal.

[0034] Moreover, in this embodiment, after milling, the thickness of the PP film is 0.1 mm. The PP layer serves as an insulating layer, and retaining a certain thickness can prevent short circuits while maintaining interlayer adhesion. Retaining a PP film thickness of 0.1 mm can ensure structural stability after lamination, and prevent the inner core board or copper foil from being exposed due to excessive milling, causing short circuits or delamination risks. Retaining a precise PP film thickness helps control the impedance matching of high-frequency signals, reduce signal reflection and attenuation, and maintain the good effect of multi-layer lamination from the electrical level and structural stability.

[0035] In this embodiment, in particular, the inverted convex mold 3 includes an integrally formed base plate 30 and a punch 31, the size of the punch 31 being smaller than the size of the base plate 30, and the shape of the punch 31 being consistent with the area where the chip 2 is exposed through the window on the first step 10 and the second step 11, and the punch 31 is fitted into the area where the chip 2 is exposed through the window, so that the upper surfaces of the base plate 30 of the inverted convex mold 3 on the first step 10 and the second step 11 are located on the same horizontal plane and then pressed together, thereby avoiding the glue overflow phenomenon caused by the PP film sinking to the middle during pressing and maintaining the uniformity of pressing.

[0036] In this embodiment, further, after lamination, the first step 10 and the second step are wrapped with a protective film and the outer layer of the PCB board 1 is subjected to solder mask treatment. The solder mask is made on the outer layer, and the film is applied to protect the entire board surface. This not only can accurately control the coverage area of ​​the solder mask layer to ensure that the pad is exposed, but also can prevent ink from contaminating non-target areas, and form a precise pattern during the exposure process to avoid misexposure.

[0037] In this embodiment, further, after the solder resist treatment, the protective film and the inverted convex mold 3 are removed, and a high-temperature PI protective film is applied.

[0038] In this embodiment, further, laser and plasma are used to clean the PCB board 1, and to clean the debris such as glue flow and foreign matter. In the above manner, the multi-chip 2 adopts a stepped mounting connection method to manufacture the PCB board 1. According to the number of chips 2 to be stacked, a corresponding number of steps are opened, and the steps are arranged in a stepped manner. The PAD and the mounted chip 2 are bonded on the corresponding steps to connect the bonding line, and the first processing protection and the second processing protection are carried out on the first step 10 and the second step 11 in turn. The window is opened according to the area where the chip 2 needs to be exposed. The above manufacturing steps are repeated according to the number of layers of the chip 2. After completion, the PP processing is carried out on the first step 10 and the second step 11, and the window processing is carried out on the area where the chip 2 needs to be exposed. The inverted convex mold 3 corresponding to each step is designed again and embedded on each chip 2, so that the upper surface of the inverted convex mold 3 on each step is in the same horizontal plane state and then pressed to avoid the overflow of glue caused by the PP film sinking to the middle during pressing, maintain the uniformity of pressing, and finally perform solder mask and foreign matter cleaning to complete the production. Through this method, the chip 2 is sunken into the PCB board 1, and the multi-layer chips 2 are arranged and connected in a sunken and stepped manner, which not only reduces the overall thickness and can develop in the direction of ultra-thinness, but also shortens the signal transmission distance to the connection distance between the chip 2 and the inner layer circuit of the PCB, thereby speeding up the transportation and processing capabilities.

[0039] The embodiments of the present application are described above. Unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A PCB board with stepped multi-chip stacking connection, characterized in that: The invention comprises a PCB board and a chip, wherein a recessed first-level step is provided on the PCB board, and a PAD is bonded to the first-level step and the chip, so that the chip is mounted on the first-level step and connected to the PAD through a bonding line, and the area exposed by the chip window on the first-level step is sequentially subjected to primary processing protection and secondary processing protection, a second-level step is provided on the PCB board, and the second-level step and the first-level step are arranged adjacent to each other in a stepped manner, the second-level step is bonded to the PAD, a chip is mounted on the second-level step and the chip is connected to the PAD on the second-level step through a bonding line, and the area exposed by the chip window on the second-level step is sequentially subjected to primary processing protection and secondary processing protection, the first-level step and the second-level step after the secondary processing protection are set through a gong PP window, and the areas exposed by the chip window on the first-level step and the second-level step are pressed together by corresponding inverted convex molds, so that the upper surfaces of the inverted convex molds on the first-level step and the second-level step are flush, and after pressing together, the outer layer of the PCB board is solder-resist treated and cleaned; The PP windowing includes laser windowing in the area where the windowing is required on the first-level step and second-level step chips. The windowing area on the PP film is larger than the exposed size of the chip, and the single side of the window on the PP film is 10 mil away from the single side of the chip. The undercut convex mold includes an integrally formed bottom plate and a punch. The punch is smaller than the bottom plate. The punch is consistent in shape with the areas exposed by the chip openings on the first and second steps. The punch fits into the areas exposed by the chip openings, so that the upper surfaces of the bottom plates of the undercut convex molds on the first and second steps are on the same horizontal plane. The one-time protection treatment sequentially prints anti-plating ink, performs exposure, development, and UV treatment according to the areas of the chip exposed by the window openings on the first and second steps, wherein the liquid photosensitive anti-plating ink is evenly covered on the surfaces of the first and second steps by screen printing, spraying, or curtain coating, and then pre-baked at 70°C-100°C to form a dry film layer, and then the ink is selectively exposed through a mask using ultraviolet light, and the ultraviolet light uses a g-line wavelength light source with a wavelength of 436nm. Subsequently, the unexposed part of the ink is dissolved by an alkaline developer to expose the substrate area to be plated, and finally the UV treatment uses a cold light source UV LED device with a power of 80W / cm.

2. The PCB board with stepped multi-chip stacking connection according to claim 1, characterized in that: The first-level step and the second-level step are arranged in a stepped manner, and the first-level step is located below the horizontal plane of the second-level step, and is arranged in a stepped network according to the number of steps.

3. The PCB board with stepped multi-chip stacking connection according to claim 1, characterized in that: The first-level step and the second-level step are milled out by a CNC machine tool.

4. The PCB board with stepped multi-chip stacking connection according to claim 1, characterized in that: The secondary processing protection is to stick a high-temperature PI protective film on the first and second steps of the chip, and then laser cut the pattern to expose the chip window area.

5. The PCB board with stepped multi-chip stacking connection according to claim 1, characterized in that: After lamination, the first step and the second step are wrapped with a protective film and subjected to an outer layer solder resist treatment of the PCB board.

6. The PCB board with stepped multi-chip stacking connection according to claim 5, characterized in that: After solder mask treatment, remove the protective film and inverted convex mold, and apply high-temperature PI protective film.

7. The PCB board with stepped multi-chip stacking connection according to claim 1, characterized in that: Laser and plasma are used to clean PCB boards.

Images