PCB structure with high-reliability via hole and manufacturing method
By using the structure of alternately overlapping core plate and adhesive sheet in the PCB board, the through-hole staggered design is formed, which solves the problem of through-hole cracking due to excessive expansion stress in high temperature environments, achieves high-reliability heat resistance, and simplifies the manufacturing process.
Patent Information
- Application Number
- CN202411952916.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-03-28
AI Technical Summary
In high temperature differential environments, existing PCB boards are prone to cracking of copper layers due to excessive expansion stress of the through holes, causing circuit failure.
The core plate and the adhesive sheet are alternately overlapped, and the through holes are randomly distributed on the core plate, and the longitudinal projection of the through holes of the adhesive sheet is distributed in a dispersed dot-like manner, forming a through hole staggered design to disperse the expansion stress.
It effectively avoids the open circuit problem caused by expansion and cracking of through holes in high temperature environments, improves the heat resistance and reliability of PCB boards, simplifies the processing process and reduces costs.
Smart Images
Figure CN119730015A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of printed circuit boards, and in particular to a PCB structure with a high-reliability through hole and a manufacturing method thereof. Background Art
[0002] PCB board is a substrate used for installing and connecting electronic components. Since the expansion coefficient of the PCB board base material is large, while the expansion coefficient of the copper layer of the PCB via hole wall is small, thermal expansion and contraction have a greater impact on the PCB via hole. When encountering a high temperature difference environment, the base material deforms and pulls the copper layer of the hole wall. The copper layer is prone to cracking due to force exceeding the limit, causing the circuit resistance to surge instantly or an open circuit, and ultimately the product fails.
[0003] There have always been two solutions to the above technical problems. One is to use a substrate with a smaller expansion coefficient, which can fundamentally reduce the expansion stress of the copper layer on the hole wall, but the disadvantage is that the material is expensive.
[0004] Another direction is the layer-adding design, which completes the manufacture of multi-layer PCB boards by gradually adding layers outward from a core board in the middle. The advantage of this direction is that the stress of the via holes is dispersed among the layers, avoiding stress concentration in the via holes, and greatly reducing the expansion stress on each via hole. However, the disadvantage is that multiple pressings are required, the processing process is cumbersome, the manufacturing process is long and the processing cost is high. Summary of the invention
[0005] In order to overcome the problems existing in the related art, one of the objects of the present invention is to provide a PCB structure with a high-reliability via hole, which does not require the use of expensive low-expansion materials, can better disperse the expansion stress of the via hole, has a simpler processing flow than the add-on layer design, and achieves the high-reliability function of the via hole at a lower cost.
[0006] A PCB structure with high-reliability vias comprises a core board and an adhesive sheet, wherein the core board and the adhesive sheet are alternately overlapped in a vertical direction, the core board is provided with M core board via holes, and the adhesive sheet is provided with N adhesive sheet via holes, wherein M and N are both integers greater than 0; the core board is provided with P layers, where P is an integer greater than 1; the adhesive sheet is provided with P-1 layers, and the longitudinal projections of the adhesive sheet via holes are distributed in a dispersed point-like manner; the core board is provided with via holes before the adhesive sheet, and the longitudinal projections of the core board via holes are randomly distributed; the longitudinal projections of the adhesive sheet via holes do not overlap with the longitudinal projections of the adjacent core board via holes in the upper and lower layers.
[0007] The core board is used as the main insulating material layer, and the adhesive sheet bonds the multiple core boards to form a stable multi-layer structure. The core board and the adhesive sheet are alternately overlapped in the vertical direction to enhance the overall mechanical stability of the PCB board, and the regular stacking method also improves the space utilization and electrical performance; the longitudinal projection of the adhesive sheet via holes is distributed in a dispersed point-like manner. Since the core board via holes are randomly opened before the adhesive sheet, the adhesive sheet via holes can effectively avoid the longitudinal area where the core board via holes are opened when opening, so as to achieve the staggered design effect of the via holes, avoid the via holes from being concentrated in the same vertical direction, and disperse the expansion stress of the via holes. In a high-temperature welding environment, it can greatly avoid the open circuit problem caused by the expansion and cracking of the via holes, thereby improving the heat resistance reliability of the PCB board.
[0008] In a preferred technical solution of the present invention, a soldering pad is further provided on the PCB structure, and the longitudinal projection of the conductive hole of the adhesive sheet and the longitudinal projection of the soldering pad do not overlap with each other.
[0009] In a preferred technical solution of the present invention, a single adhesive sheet conductive hole is connected to a plurality of core board conductive holes during current transmission, and a single adhesive sheet conductive hole conducts a plurality of current transmission paths.
[0010] The setting of a single adhesive sheet via hole connecting multiple core board via holes reduces the inner layer via penetration design, leaving more space for inner layer wiring, improving circuit connectivity and optimizing circuit layout; a single adhesive sheet via hole connects multiple current transmission paths, realizing a more efficient wiring design in a limited space.
[0011] In a preferred technical solution of the present invention, when M is greater than N, the M current transmission paths start to flow from the M core board via holes of the first layer of the core board into the N adhesive sheet via holes of the first layer of the adhesive sheet in the vertical direction, and at the same time, after passing through the N adhesive sheet via holes of the first layer of the adhesive sheet, they flow to the M core board via holes of the second layer of the core board, until the M current transmission paths flow out from the M core board via holes of the Pth layer of the core board.
[0012] The unique flow direction of the current transmission path reflects the high utilization rate of the adhesive sheet vias in the structure. Since M is greater than N, there must be a possibility that a certain adhesive sheet via will conduct multiple current transmission paths at the same time. When a single-layer adhesive sheet is only provided with a single adhesive sheet via, multiple current transmission paths can also pass through the adhesive sheet via at the same time, and then flow from the adhesive sheet via to multiple core board vias, thereby improving the space utilization rate of the PCB board.
[0013] A second object of the present invention is to provide a method for manufacturing a PCB structure having a high-reliability via hole, comprising:
[0014] S1: cutting the core board substrate to open the core board conductive holes, performing hole metallization treatment on the core board conductive holes, and then manufacturing inner layer circuits;
[0015] S2: laminating the multi-layer core board and the adhesive sheet at one time, opening a longitudinal long through hole, and performing hole metallization treatment;
[0016] S3: processing the longitudinal long through hole into a buried hole by double-sided controlled depth drilling;
[0017] S4: Filling the longitudinal long through hole with resin and then manufacturing the outer layer circuit.
[0018] By simplifying the pressing process, only one pressing is required to achieve the simultaneous production of inner layer circuits and the interconnection and conduction of each layer of circuits. Compared with the cumbersome process of multiple pressings in the traditional multi-layer PCB structure manufacturing, it greatly shortens the production cycle and reduces processing costs. Different from the common steps, the double-sided controlled depth drilling technology is used to process the local conductive holes of the adhesive sheet, which effectively shortens the length of the conductive holes, reduces the expansion stress, and enhances the hole wall structure strength and electrical insulation performance through resin filling, while leaving more wiring space and device installation space for the outer layer of the PCB.
[0019] In a preferred technical solution of the present invention, in S1, the core board via holes are randomly opened at any position, and after the via holes are opened in each layer of the core board, the inner layer circuits can be manufactured at the same time, and then browning treatment is performed.
[0020] In the existing layer-building design, due to the limitation of material properties, it is necessary to open holes layer by layer to make inner layer circuits, and circuits cannot be made on multiple layers of boards at the same time, so the pressing step needs to be repeated many times. However, since the present method opens conductive holes on each layer of the core board in advance, each layer of the core board can make inner layer circuits at the same time, so only one pressing step is required, shortening the process flow.
[0021] In a preferred technical solution of the present invention, in S2, the number of the longitudinal long through holes is equal to the total number of the conductive holes of the adhesive sheet.
[0022] In a preferred technical solution of the present invention, in S2, it is necessary to ensure that no pads or functional circuits are provided on the longitudinal area where the longitudinal long through hole is provided.
[0023] By rationally planning the positions of the longitudinal long through holes, the crosstalk between different signal lines can be reduced.
[0024] In a preferred technical solution of the present invention, in S3, the local conductive holes of the adhesive sheet are processed by double-sided controlled depth drilling, and each of the longitudinal long through holes is processed to form an effective conductive hole of the adhesive sheet.
[0025] The double-sided controlled depth drilling method is used to process the local via holes in the bonding sheet, shortening the length of the via holes between each layer and effectively reducing the expansion stress.
[0026] In a preferred technical solution of the present invention, in said S4, the step after the resin filling further includes grinding the surface of the PCB and forming a copper layer by electroplating, and then manufacturing the outer layer circuit.
[0027] After the outer layer circuit is completed, the post-process flow is required, including the production of solder mask layer, silk screen marking, finished product testing and other steps.
[0028] The beneficial effects of the present invention are:
[0029] The present invention provides a PCB structure with high-reliability vias, which adopts a staggered distribution design of vias to avoid the vias from being concentrated in the same vertical direction, so as to disperse the expansion stress of the vias, and to greatly avoid the open circuit problem caused by the expansion and cracking of the vias in a high-temperature welding environment, and thus has very high heat-resistant reliability; on the other hand, adjacent layers are independently interconnected, and the vias of the same network can be shared, which can reduce the penetration design of the inner layer vias and leave more inner layer wiring space.
[0030] The present application also provides a manufacturing method for the above-mentioned PCB structure, which does not require the use of expensive low-expansion materials. In conventional layer-building designs, multi-layer PCB structures need to be pressed multiple times, and the process is cumbersome. In the manufacturing method of the present invention, since via holes are pre-opened on each layer of core boards, each layer of core boards can simultaneously produce inner layer circuits, so only one pressing step is required, and the interconnection and conduction of each layer of circuits can be achieved without cumbersome repeated pressing and circuit production, which greatly shortens the production cycle and reduces processing costs; at the same time, double-sided controlled deep drilling is used to process local via holes of the adhesive sheet, shortening the length of the via holes between each layer, effectively reducing expansion stress, and then filling the holes with resin to leave more wiring space and device installation space for the outer layer of the PCB. Therefore, compared with conventional layer-building designs, the manufacturing method of the present invention has a simpler processing flow and can achieve high reliability functions of via holes at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 It is a schematic diagram of via cracking in the prior art;
[0032] Figure 2 It is a schematic diagram of the structure of the layer-increasing design in the prior art;
[0033] Figure 3 is a cross-sectional view of a PCB structure with a high-reliability via provided in Embodiment 1 of the present invention;
[0034] Figure 4It is a conduction relationship diagram of a core board through hole and an adhesive sheet through hole of a PCB structure with a high-reliability through hole provided in Example 1 of the present invention;
[0035] Figure 5 is a cross-sectional view of a PCB structure with a high-reliability via provided in Embodiment 2 of the present invention;
[0036] Figure 6 is a schematic process flow diagram of a method for manufacturing a PCB structure with a high-reliability via provided in Embodiment 3 of the present invention;
[0037] Figure 7 This is one of the key process schematic diagrams of a method for manufacturing a PCB structure with a high-reliability via provided in Example 3 of the present invention;
[0038] Figure 8 This is the second schematic diagram of the key process of the method for manufacturing a PCB structure with high-reliability conductive holes provided in Example 3 of the present invention.
[0039] Reference numerals:
[0040] 1. Core board; 2. Adhesive sheet; 3. Core board via hole; 4. Adhesive sheet via hole. DETAILED DESCRIPTION
[0041] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.
[0042] PCB board is a substrate for installing and connecting electronic components. Since the expansion coefficient of the PCB substrate is large, while the expansion coefficient of the copper layer of the PCB through-hole wall is small, thermal expansion and contraction have a greater impact on the PCB through-hole. When encountering a high temperature difference environment, the deformation of the substrate will pull the copper layer of the hole wall, and the copper layer is prone to cracking due to excessive force (such as Figure 1 As shown in the figure, the circuit resistance may increase instantly or an open circuit may occur, which may lead to product failure.
[0043] There have always been two solutions to the above technical problems. One is to use a substrate with a smaller expansion coefficient, which can fundamentally reduce the expansion stress of the copper layer on the hole wall, but the disadvantage is that the material is expensive.
[0044] Another direction is to add layers, such as Figure 2As shown, the multi-layer PCB board is manufactured by gradually adding layers outward from a core board in the middle. The advantage of this direction is that the stress of the via hole is dispersed between the layers, avoiding the stress concentration of the via hole, and greatly reducing the expansion stress of each via hole. However, the disadvantage is that multiple pressings are required, the processing process is cumbersome, the manufacturing process is long and the processing cost is high.
[0045] Based on this, the present application provides a PCB structure with high-reliability vias and a manufacturing method.
[0046] Example 1
[0047] See also Figure 1-Figure 4 The present embodiment provides a PCB structure with a high-reliability via, including a core board 1 and an adhesive sheet 2. The core board 1 is the main insulating material layer in the PCB multi-layer structure, and can be composed of glass fiber and epoxy resin. The adhesive sheet 2 is also an insulating material, commonly polyimide, FR-4, etc., which is used to bond the core board 1 together to form a multi-layer PCB structure. The core board 1 and the adhesive sheet 2 are alternately overlapped in the vertical direction according to a rule to form a multi-layer PCB structure.
[0048] The core board 1 is provided with M core board via holes 3, and the adhesive sheet 2 is provided with N adhesive sheet via holes 4, wherein M and N are both integers greater than 0; the core board 1 is provided with P layers, and P is an integer greater than 1; the adhesive sheet 2 is provided with P-1 layers, and the longitudinal projection of the adhesive sheet via holes 4 is distributed in dispersed point-like manner; the core board 1 is provided with via holes before the adhesive sheet 2, and the longitudinal projection of the core board via holes 3 is randomly distributed.
[0049] The core board 1 is used as the main insulating material layer, and the adhesive sheet 2 bonds the multiple layers of the core board 1 to form a stable multi-layer structure. The core board 1 and the adhesive sheet 2 are alternately stacked from top to bottom, which enhances the overall mechanical stability of the PCB board. The regular stacking method also improves space utilization and electrical performance.
[0050] In this embodiment, the longitudinal projection of the adhesive sheet via hole 4 does not overlap with the longitudinal projection of the adjacent core board via hole 3 in the upper and lower layers.
[0051] The longitudinal projection of the adhesive sheet via hole 4 is distributed in a dispersed point shape. Since the core board via hole 3 is randomly opened before the adhesive sheet 2, the adhesive sheet via hole 4 can effectively avoid the longitudinal area where the core board via hole 3 is opened when it is opened, so as to achieve the effect of staggered design of the via holes, avoid the via holes from being concentrated in the same vertical direction, disperse the expansion stress of the via holes, and improve its heat resistance reliability.
[0052] Specifically, if Figure 3As shown, A is a via hole of the bottom core board 1, and the longitudinal length of the via hole is the vertical thickness from the upper surface to the lower surface of the bottom core board 1. Two circuit boards with via holes of different longitudinal lengths were subjected to heat cycle life test in the same temperature range, and the results are as follows:
[0053] (1) When the longitudinal length of the circuit board via hole is 0.2 mm, the via hole has a heat resistance cycle life of 504 times in the temperature range of -55°C to 125°C; when the longitudinal length of the circuit board via hole is 1.6 mm, the heat resistance cycle life of the via hole is 159 times in the above temperature range; this proves that the smaller the longitudinal length of the via hole, the higher the heat resistance reliability;
[0054] (2) When the longitudinal length of the circuit board via hole is 0.2 mm, the barrel stress of the via hole is 174.6 MPa; when the longitudinal length of the circuit board via hole is 1.6 mm, the barrel stress of the via hole is 177.3 MPa. Since the greater the barrel stress of the via hole, the easier it is to crack, the present invention staggers the via holes to avoid the via holes being concentrated in the same vertical direction, thereby reducing the cracking of the via holes due to thermal expansion.
[0055] The PCB structure is also provided with a soldering pad, and the longitudinal projection of the adhesive sheet via 4 does not overlap with the longitudinal projection of the soldering pad, so as to avoid crosstalk between different signal lines.
[0056] A single adhesive sheet via 4 is connected to a plurality of core board vias 3 during current transmission, that is, the adhesive sheet vias 4 of the same network can be shared, which can reduce the inner layer via penetration design and leave more inner layer wiring space.
[0057] In practical applications, the diameters of the core plate via holes 3 and the adhesive sheet via holes 4 are both smaller than 0.2 mm; and the single-layer thicknesses of the core plate 1 and the adhesive sheet 2 are both smaller than 0.2 mm.
[0058] The micro-aperture design helps to achieve high-density circuit layout while reducing signal transmission loss; controlling the single-layer thickness of the core board 1 and the adhesive sheet 2 helps to reduce the overall weight of the PCB board, making it more suitable for portable devices.
[0059] like Figure 3 As shown, a single bonding sheet conducting hole 4 conducts multiple current transmission paths;
[0060] The multiple current transmission paths start from the multiple core plate conducting holes 3 of a single core plate 1, pass through the single adhesive sheet conducting hole 4, and then end at the multiple core plate conducting holes 3 of another core plate 1;
[0061] A single adhesive sheet via 4 connecting multiple current transmission paths can achieve a more efficient wiring design in a limited space.
[0062] In actual applications, when M is equal to 2 and N is equal to 1, the two current transmission paths start to flow from the two core board via holes 3 of the first layer of the core board 1 into the single adhesive board via hole 4 of the first layer of the adhesive sheet 2 in the vertical direction from top to bottom, and then flow to the two core board via holes 3 of the second layer of the core board 1 after passing through the single adhesive board via hole 4 of the first layer of the adhesive sheet 2, until the two current transmission paths flow out from the two core board via holes 3 of the core board 1 of the Pth layer.
[0063] The unique flow direction of the current transmission path reflects the high utilization rate of the adhesive sheet via 4 in the structure. When the single-layer adhesive sheet 2 is only provided with a single adhesive sheet via 4, multiple current transmission paths can also pass through the adhesive sheet via 4 at the same time, and then flow from the adhesive sheet via 4 to multiple core board vias 3, thereby improving the space utilization rate of the PCB board.
[0064] The present invention provides a PCB structure with high-reliability vias, which adopts a staggered distribution design of vias to avoid the vias from being concentrated in the same vertical direction, so as to disperse the expansion stress of the vias, and to greatly avoid the open circuit problem caused by the expansion and cracking of the vias in a high-temperature welding environment, and thus has very high heat-resistant reliability; on the other hand, adjacent layers are independently interconnected, and the vias of the same network can be shared, which can reduce the penetration design of the inner layer vias and leave more inner layer wiring space.
[0065] Example 2
[0066] See also Figure 5 The present embodiment provides a PCB structure with a high-reliability via, including a core board 1 and an adhesive sheet 2. The core board 1 is the main insulating material layer in the PCB multi-layer structure, and can be composed of glass fiber and epoxy resin. The adhesive sheet 2 is also an insulating material, commonly polyimide, FR-4, etc., which is used to bond the core board 1 together to form a multi-layer PCB structure. The core board 1 and the adhesive sheet 2 are alternately overlapped in the vertical direction according to a rule to form a multi-layer PCB structure.
[0067] The core board 1 is provided with M core board conducting holes 3 , and the adhesive sheet 2 is provided with N adhesive sheet conducting holes 4 , wherein both M and N are integers greater than 0.
[0068] Specifically, the core board 1 is provided with P layers, where P is an integer greater than 1; the adhesive sheet 2 is provided with P-1 layers, and the longitudinal projection of the conductive holes 4 of the adhesive sheet is distributed in a dispersed point shape; the conductive holes of the core board 1 are opened before the adhesive sheet 2, and the longitudinal projection of the conductive holes 3 of the core board is randomly distributed, such as Figure 5 It can be seen that the longitudinal projection of the adhesive sheet via hole 4 has three points.
[0069] In this embodiment, the core plate via holes 3 on each layer of the core plate 1 are provided at the overlapping positions of the longitudinal projections, such as Figure 5 It can be seen that the longitudinal projection of the core board via hole 3 has only one point, and the longitudinal projection of the core board via hole 3 does not overlap with the longitudinal projections of all the adhesive sheet via holes 4. The staggered design of the core board via hole 3 and the adhesive sheet via hole 4 can better disperse the expansion stress of the via hole and improve its heat-resistant reliability.
[0070] A single adhesive sheet via 4 is connected to a plurality of core board vias 3 during current transmission, that is, the adhesive sheet vias 4 of the same network can be shared, which can reduce the inner layer via penetration design and leave more inner layer wiring space.
[0071] In practical applications, the diameters of the core plate via holes 3 and the adhesive sheet via holes 4 are both smaller than 0.2 mm; and the single-layer thicknesses of the core plate 1 and the adhesive sheet 2 are both smaller than 0.2 mm.
[0072] The present invention provides a PCB structure with high-reliability vias, which adopts a staggered distribution design of vias to avoid the vias from being concentrated in the same vertical direction, so as to disperse the expansion stress of the vias, and to greatly avoid the open circuit problem caused by the expansion and cracking of the vias in a high-temperature welding environment, and thus has very high heat-resistant reliability; on the other hand, adjacent layers are independently interconnected, and the vias of the same network can be shared, which can reduce the penetration design of the inner layer vias and leave more inner layer wiring space.
[0073] Example 3
[0074] See also Figure 5-Figure 8 This embodiment provides a method for manufacturing the PCB structure of embodiment 2, comprising the following steps:
[0075] S1: cutting the core board 1 substrate to open the core board conductive hole 3, performing hole metallization treatment on the core board conductive hole 3 to make an inner layer circuit;
[0076] S2: laminating the multi-layer core board 1 and the adhesive sheet 2 at one time, opening a longitudinal long through hole, and performing hole metallization treatment;
[0077] S3: processing the longitudinal long through hole into a buried hole by double-sided controlled depth drilling;
[0078] S4: filling the position of the longitudinal long through hole with resin and then manufacturing the outer layer circuit;
[0079] S5: Carry out post-process processes such as solder mask production, silk screen marking, and finished product testing.
[0080] By simplifying the pressing process, only one pressing is required to achieve the simultaneous production of inner layer circuits and the interconnection and conduction of each layer of circuits. Compared with the cumbersome process of multiple pressings in the traditional multi-layer PCB structure manufacturing, it greatly shortens the production cycle and reduces processing costs. Different from the common steps, the double-sided controlled depth drilling technology is used to process the local conductive holes of the adhesive sheet, which effectively shortens the length of the conductive holes, reduces the expansion stress, and enhances the hole wall structure strength and electrical insulation performance through resin filling, while leaving more wiring space and device installation space for the outer layer of the PCB.
[0081] Specifically, in S1, the core board via holes 2 are randomly opened at any position, and after the via holes are opened in each layer of the core board 1, inner layer circuits can be manufactured at the same time, and then browning treatment is performed.
[0082] In the existing layer-building design, due to the limitation of material properties, it is necessary to open holes layer by layer to make inner layer circuits, and circuits cannot be made on multiple layers of boards at the same time, so the pressing step needs to be repeated many times. However, since the present method opens conductive holes on each layer of the core board in advance, each layer of the core board can make inner layer circuits at the same time, so only one pressing step is required, shortening the process flow.
[0083] Furthermore, in S2, the number of the longitudinally long through holes is equal to the total number of the conductive holes in the adhesive sheet.
[0084] Furthermore, in S2, it is necessary to ensure that there are no pads and functional circuits in the longitudinal area where the longitudinal long through hole is opened, and the position of the longitudinal long through hole is reasonably planned to reduce crosstalk between different signal circuits.
[0085] In S3, the local conductive holes of the adhesive sheet are processed by double-sided controlled depth drilling, and each of the longitudinal long through holes is processed to form an effective adhesive sheet conductive hole 4. The local conductive holes of the adhesive sheet are processed by double-sided controlled depth drilling, which shortens the length of the conductive holes between each level and effectively reduces the expansion stress.
[0086] In the above S4, the steps after the resin filling also include grinding the surface of the PCB and forming a copper layer by electroplating, and then manufacturing the outer layer circuit.
[0087] In S5, the solder resist layer covers the circuit board to protect the copper conductor from oxidation and prevent short circuits during welding. The silk screen logo is a mark of the component number, circuit board name, etc., so as to facilitate identification during subsequent assembly and maintenance. The finished product inspection includes appearance inspection, electrical performance testing, etc. to ensure that the product quality meets the design requirements.
[0088] The present invention discloses a manufacturing method of a PCB structure with a high-reliability via hole, which does not require the use of expensive low-expansion materials. In a conventional layer-building design, a multi-layer PCB structure needs to be pressed multiple times, and the process is cumbersome. In the manufacturing method of the present invention, since the via holes are opened in advance on each layer of the core board 1, each layer of the core board 1 can simultaneously manufacture the inner layer circuit, and therefore only one pressing step is required, and the interconnection and conduction of each layer of circuits can be achieved without cumbersome repeated pressing and circuit manufacturing, which greatly shortens the manufacturing cycle and reduces the processing cost; at the same time, double-sided controlled deep drilling is used to process the local via holes of the adhesive sheet, the length of the via holes between each layer is reduced, the expansion stress is effectively reduced, and then the holes are filled with resin to leave more wiring space and device installation space for the outer layer of the PCB. Therefore, compared with the conventional layer-building design, the manufacturing method of the present invention has a simpler processing flow and can achieve the high reliability function of the via hole at a lower cost.
[0089] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.
[0090] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.
[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A PCB structure with a high reliability via hole, characterized in that: The invention comprises a core plate (1) and an adhesive sheet (2), wherein the core plate (1) and the adhesive sheet (2) are alternately overlapped in a vertical direction, the core plate (1) is provided with M core plate conducting holes (3), and the adhesive sheet (2) is provided with N adhesive sheet conducting holes (4), wherein M and N are both integers greater than 0; The core plate (1) is provided with P layers, where P is an integer greater than 1; The adhesive sheet (2) is provided with a P-1 layer, and the longitudinal projection of the adhesive sheet via holes (4) is distributed in a dispersed point shape.
2. A PCB structure with high reliability vias according to claim 1, characterized in that: The core plate (1) is provided with conducting holes before the adhesive sheet (2), and the conducting holes (3) of the core plate are randomly distributed in longitudinal projection.
3. A PCB structure with high reliability vias according to claim 2, characterized in that: The longitudinal projection of the conductive hole (4) of the adhesive sheet does not overlap with the longitudinal projection of the conductive hole (3) of the core plate adjacent to the upper and lower layers.
4. The PCB structure with high reliability vias according to claim 1, characterized in that: A soldering pad is also provided on the PCB structure, and the longitudinal projection of the adhesive sheet via hole (4) does not overlap with the longitudinal projection of the soldering pad.
5. The PCB structure with high reliability vias according to claim 1, characterized in that: A single adhesive sheet conducting hole (4) conducts a plurality of current transmission paths; When M is greater than N, the M current transmission paths flow from the M core board conductive holes (3) of the first layer of the core board (1) into the N adhesive sheet conductive holes (4) of the first layer of the adhesive sheet (2) in the vertical direction, and then flow to the M core board conductive holes (3) of the second layer of the core board (1) after passing through the N adhesive sheet conductive holes (4) of the first layer of the adhesive sheet (2), until the M current transmission paths flow out from the M core board conductive holes (3) of the Pth layer of the core board (1).
6. A method for manufacturing a PCB structure with a high reliability via hole according to claim 1, characterized in that: The following steps are involved: S1: cutting the core board (1) substrate to open the core board conductive hole (3), performing hole metallization treatment on the core board conductive hole (3) and then manufacturing the inner layer circuit; S2: laminating the multi-layer core board (1) and the adhesive sheet (2) at one time, opening a longitudinal long through hole, and performing hole metallization treatment; S3: processing the longitudinal long through hole into a buried hole by double-sided controlled depth drilling; S4: Filling the longitudinal long through hole with resin and then manufacturing the outer layer circuit.
7. The method for manufacturing a PCB structure with a high-reliability via according to claim 6, characterized in that: In S1, the core board via holes (3) are randomly opened at any position, and after the via holes are opened in each layer of the core board (1), the inner layer circuits can be manufactured at the same time, and then browning treatment is performed.
8. The method for manufacturing a PCB structure with a high-reliability via according to claim 6, characterized in that: In S2, the number of the longitudinal long through holes is equal to the total number of the conductive holes (4) in the adhesive sheet.
9. The method for manufacturing a PCB structure with a high-reliability via hole according to claim 6, characterized in that: In S2, it is necessary to ensure that no pads or functional circuits are provided in the longitudinal region where the longitudinal long through hole is provided.
10. The method for manufacturing a PCB structure with a high-reliability via according to claim 6, characterized in that: In S3, a double-sided controlled depth drilling method is used to process the local conductive holes of the adhesive sheet (2), and each of the longitudinal long through holes is processed to form an effective conductive hole (4) of the adhesive sheet.