Plated-through hole manufacturing method and circuit board

Abstract

The invention provides a plated-through hole manufacturing method and a circuit board. The plated-through hole manufacturing method comprises the following steps: providing a daughter board; a groove is formed in the daughter board; filling the groove with a first filler; alternately stacking the daughter boards, and pressing to form a mother board; a first hole is formed in the mother board, the first filler is exposed out of the side wall of the first hole, and the first filler divides other areas of the side wall in the circumferential direction; forming a metal layer on the side wall of the first hole; removing the first filler to enable the metal layer formed on the surface of the first filler to lose support; and applying pressure to the metal layer to destroy the metal layer which loses the support. According to the manufacturing method of the plated-through hole, the metal layer which originally covers the whole side wall is broken in the circumferential direction and divided into the multiple areas by damaging the metal layer which loses the support, the metal layers located in the different areas can be used for achieving different interlayer communication, and therefore the manufacturing method of the plated-through hole is beneficial to meeting various conduction requirements of circuit patterns.

Description

Technical Field

[0001] The present application relates to the field of circuit boards, and in particular to a method for making a metallized hole and a circuit board. Background Art

[0002] The circuit board uses metallized holes to connect the circuit patterns of different layers. In some scenarios, the circuit patterns of certain layers need to be disconnected, so it is necessary to selectively remove the metal layers between certain layers through copper reduction operations such as etching to create disconnected metallized holes.

[0003] For complex circuit boards, there may be multiple conduction requirements between circuit patterns. For this reason, the relevant technology generally produces multiple metallized holes, each of which adopts a different disconnection design. However, multiple metallized holes will occupy the available space of the circuit patterns, which is not conducive to the miniaturization of the circuit board. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method for making a metallized hole and a circuit board, which helps to make a metallized hole that is disconnected in the circumferential direction and meets various conduction requirements of the circuit pattern.

[0005] The method for making a metallized hole provided in the present application includes: providing a sub-board; making a groove on the sub-board; filling the groove with a first filler; alternately stacking the sub-boards and pressing them together to form a motherboard; opening a first hole on the motherboard, the side wall of the first hole exposing the first filler, and the first filler circumferentially separating the remaining area of ​​the side wall; forming a metal layer on the side wall of the first hole; removing the first filler so that the metal layer formed on the surface of the first filler loses support; and applying pressure to the metal layer to destroy the metal layer that has lost support.

[0006] The method for making metallized holes provided in the present application has at least the following technical effects: by pre-placing a first filler before lamination and removing the first filler after metallization, the corresponding metal layer can be made to lose support, so that the metal layer that has lost support can be destroyed by applying pressure, and the metal layer that originally covers the entire side wall is disconnected in the circumferential direction and separated into multiple areas. The metal layers located in different areas can be used to achieve different inter-layer connections. Therefore, the method for making metallized holes helps to meet various conduction requirements of circuit graphics.

[0007] According to some embodiments of the present application, the first filler includes a first block and a second block, the first block extends in the stacking direction and passes through the plurality of sub-plates, the first block separates the remaining areas of the side wall in the circumferential direction, and the second block is arranged between two adjacent first blocks, the second block separates the remaining areas of the side wall in the stacking direction.

[0008] According to some embodiments of the present application, after the metal layer that has lost its support is destroyed, a non-conductive second filler is used to fill the first hole.

[0009] According to some embodiments of the present application, after the metal layer is formed, a second hole is opened on the motherboard, the second hole exposes the first filler, and the first filler is removed through the second hole.

[0010] According to some embodiments of the present application, the first filler is removed by melting the first filler at high temperature or powdering the first filler at low temperature.

[0011] According to some embodiments of the present application, the melting point of the first filler is greater than or equal to 180°C, and the first filler has any of the following characteristics: the melting point of the first filler is between 210°C and 270°C; the first filler can be powdered at a temperature below 13.2°C.

[0012] According to some embodiments of the present application, the first filler includes tin, and the first filler is removed by any of the following methods: applying a low temperature to the area where the first filler is located to cause the first filler to undergo tin transformation into powder; or applying a high temperature to the area where the first filler is located to melt the first filler.

[0013] According to the circuit board provided in the present application, the circuit board is manufactured by the metallized hole manufacturing method provided in the present application.

[0014] The circuit board provided according to the present application includes a sub-board and a metal layer, wherein the sub-boards are stacked, and the metal layer extends along the stacking direction of the sub-boards to conduct circuit patterns located in different layers. Around an axis parallel to the stacking direction, multiple groups of the metal layers are arranged at intervals along the circumferential direction.

[0015] According to some embodiments of the present application, a group of metal layers includes a plurality of the metal layers, and the plurality of metal layers in the same group are spaced apart along the stacking direction.

[0016] The circuit board provided in the present application can meet various conduction requirements of the circuit graphics by setting up multiple metal layers. The various metal layers are surrounded together and separated in the circumferential direction, so that the interlayer conduction of the circuit graphics can be concentrated together, reducing the number of metallized holes, helping to make the design of the circuit graphics more compact, and helping to achieve a miniaturized design of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide further understanding of the technical solution disclosed in the present application and constitute a part of the specification. Together with the embodiments disclosed in the present application, they are used to explain the technical solution disclosed in the present application and do not constitute a limitation on the technical solution disclosed in the present application.

[0018] Figure 1 It is a schematic diagram of the structure of the metallized hole in the related art;

[0019] Figure 2 is a schematic diagram of the structure of a circuit board according to an embodiment of the present application;

[0020] Figure 3 is a schematic structural diagram of a circuit board according to an embodiment of the present application, wherein the interlayer conduction function of the metal layer is more clearly demonstrated through partial sectioning;

[0021] Figure 4 It is a schematic diagram of the process of the method for making a metallized hole according to an embodiment of the present application;

[0022] Figure 5 It is a schematic diagram of the manufacturing process of the circuit board of the embodiment of the present application;

[0023] Figure 6 It is a schematic diagram of the manufacturing process of the circuit board of the embodiment of the present application.

[0024] Reference numerals:

[0025] The core board 100 , the substrate 110 , the circuit pattern 120 , the bonding sheet 200 , the metal layer 300 , the first filler 400 , the first block 410 , the second block 420 , the groove 500 , and the first hole 600 . DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0027] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0028] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0029] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0031] Metallized holes are used to achieve inter-layer conduction of circuit patterns. In some related technologies, circuit patterns of certain layers need to be disconnected, so disconnected metallized holes need to be made.

[0032] Figure 1 An embodiment of a disconnected metallized hole in the related art is shown, referring to Figure 1 The circuit board is formed by laminating three layers of core boards 100 and two layers of bonding sheets 200. The core board 100 is a double-sided copper-clad board. The core board 100 includes a substrate 110 and two layers of circuit graphics 120 located on both sides of the substrate. Therefore, the circuit board has a total of six layers of circuit graphics 120.

[0033] For ease of description, the circuit patterns 120 of each layer are numbered from top to bottom. By disconnecting the metal layer 300 of the metallized hole, the circuit patterns 120 of the first to fourth layers are connected to each other, the circuit patterns 120 of the fifth and sixth layers are connected to each other, but the circuit patterns 120 of the fourth and fifth layers are disconnected.

[0034] In the related art, a metallized hole can only realize one disconnection mode (such as Figure 1 In the embodiment, the circuit patterns 120 of the fourth and fifth layers are disconnected). For a circuit board with a more complex design, there may be multiple conduction requirements at the same time, which can only be achieved through different disconnection methods. For this reason, it is necessary to make multiple metallized holes on the circuit board, thereby occupying the available space of the circuit pattern, which is not conducive to the high-density design of the circuit board and is not suitable for miniaturization of the circuit board.

[0035] To this end, the present application provides a circuit board that can utilize one metallized hole to meet multiple conduction requirements, thereby helping to achieve miniaturization of the circuit board.

[0036] Reference Figure 2 and Figure 3 According to the embodiment of the present application, the circuit board includes a sub-board and a metal layer 300. The sub-boards are stacked, and the metal layer 300 extends along the stacking direction of the sub-boards to conduct the circuit patterns 120 located in different layers. Around an axis parallel to the stacking direction, multiple groups of metal layers 300 are arranged at intervals along the circumferential direction.

[0037] It can be understood that the sub-board includes a core board 100 and a bonding sheet 200, and the core board 100 includes a substrate 110 and a circuit pattern 120. During the manufacturing process, the complete metal layer 300 on the side wall of the metallized hole is separated circumferentially (that is, a circumferentially disconnected metallized hole is formed), thereby generating a plurality of groups of independent metal layers 300 spaced apart around an axis (that is, the original axis of the metallized hole), each of which can be used to achieve a disconnection method.

[0038] For example, in Figure 2 and Figure 3 In the illustrated embodiment, the circuit pattern 120 is divided into six layers, which are numbered from the first layer to the sixth layer in order from top to bottom. The circuit board is manufactured with four groups of metal layers 300 using one metallized hole.

[0039] Among them, one group of metal layers 300 is used to achieve conduction from the first layer to the sixth layer of the circuit graphics 120; one group of metal layers 300 is used to achieve conduction from the first layer to the second layer, and from the third layer to the sixth layer of the circuit graphics 120, while the second layer and the third layer are disconnected; one group of metal layers 300 is used to achieve conduction from the first layer to the third layer, and from the fourth layer to the sixth layer of the circuit graphics 120, while the third layer and the fourth layer are disconnected; one group of metal layers 300 is used to achieve conduction from the first layer to the fourth layer, and from the fifth layer to the sixth layer of the circuit graphics 120, while the fourth layer and the fifth layer are disconnected.

[0040] That is to say, the circuit board uses one metallized hole to achieve seven different conduction requirements (1 to 7 full conduction, 1 to 2 conduction, 1 to 3 conduction, 1 to 4 conduction, 3 to 6 conduction, 4 to 6 conduction, 5 to 6 conduction).

[0041] Therefore, the circuit board can use one metallized hole to meet multiple conduction requirements, which helps to achieve miniaturization of the circuit board.

[0042] It should be pointed out that Figure 2 and Figure 3 A preferred disconnection design method is shown, that is, a group of metal layers 300 includes multiple metal layers 300, and the multiple metal layers 300 in the same group are arranged at intervals along the stacking direction, so that a group of metal layers 300 can be used to meet multiple non-conflicting conduction requirements.

[0043] However, this design is not the only feasible one. For example, there may be only one metal layer 300 in a group of metal layers 300 to achieve a conduction requirement (which may be Figure 2 and Figure 3 The full conduction in the embodiment may also be partial conduction). In specific implementation, the two design methods may be flexibly combined according to the specific requirements of the circuit pattern (such as the requirements related to signal-to-noise and interference), and this application does not limit this.

[0044] In addition, although the metallized holes need to be made first and then separated to form multiple groups of metal layers 300 of the present application during the manufacturing process, the metallized holes can also be filled (that is, the metallized holes can be made to disappear) in the final circuit board product. Filling helps to protect the metal layer 300 and can also improve the structural strength of the circuit board.

[0045] In the related art, the disconnected metallized holes are usually made by pre-burying anti-plating ink. However, due to the isotropic electroplating characteristics, the metal layer will not be neatly disconnected at the edge of the ink during electroplating, but will extend slightly to one side of the ink. Since the hole diameter of the circuit board is generally small, if the anti-plating ink is used to make the circumferentially disconnected metallized holes, the metal layer will easily cross the anti-plating ink and connect together during electroplating. This problem hinders the implementation of the circuit board with circumferentially disconnected metallized holes.

[0046] To this end, the present application also provides a method for producing a metallized hole, which helps to produce a metallized hole that is disconnected in the circumferential direction while meeting various conduction requirements of the circuit pattern. Therefore, the circuit board of the present application can be produced by the metallized hole production method.

[0047] Reference Figure 4 , and combined with Figure 5 and Figure 6According to the metallized hole manufacturing method of the embodiment of the present application, the following steps are included:

[0048] Step S110: providing a daughter board.

[0049] It can be understood that the sub-board includes a core board 100 and a bonding sheet 200. Figure 5 and Figure 6 In the illustrated embodiment, the circuit board includes a three-layer core board 100 and a two-layer bonding sheet 200 .

[0050] Step S120: cutting a slot 500 on the daughter board.

[0051] Step S130 : filling the groove 500 with the first filler 400 .

[0052] Step S140: alternately stacking the daughter boards and pressing them together to form a mother board.

[0053] Step S150 : a first hole 600 is opened on the motherboard, the sidewall of the first hole 600 exposes the first filler 400 , and the first filler 400 separates the remaining area of ​​the sidewall in the circumferential direction.

[0054] It is understandable that the first hole 600 is used to make a metallized hole. Figure 5 and Figure 6 In the illustrated embodiment, the first filler 400 divides the remaining area of ​​the side wall into four parts in the circumferential direction.

[0055] Step S160 : forming a metal layer 300 on the sidewall of the first hole 600 .

[0056] It can be understood that the metal layer 300 is formed by electroplating, and the metal layer 300 is completely formed on all surfaces of the sidewall of the first hole 600 .

[0057] Step S170 : removing the first filler 400 , so that the metal layer 300 formed on the surface of the first filler 400 loses support.

[0058] Step S180: applying pressure to the metal layer 300 to damage the metal layer 300 that has lost its support.

[0059] According to the method for making a metallized hole in an embodiment of the present application, a first filler 400 is pre-placed before lamination and the first filler 400 is removed after metallization to form a cavity in the circuit board. This can cause the corresponding metal layer 300 to lose support, thereby destroying the metal layer 300 that has lost support by applying pressure, and the metal layer 300 that originally covers the entire side wall is disconnected in the circumferential direction and separated into multiple areas. The metal layers 300 located in different areas can be used to achieve different interlayer connections. Therefore, the method for making a metallized hole helps to meet various conduction requirements of circuit graphics.

[0060] Furthermore, since a complete metal layer 300 is formed first and then the metal layer 300 is disconnected in the circumferential direction by destroying part of the metal layer 300, the metallized hole manufacturing method can avoid the problem of the metal layer 300 crossing the anti-plating ink when the metal layer 300 is selectively electroplated in the related technology, and is therefore suitable for manufacturing metallized holes that are disconnected in the circumferential direction.

[0061] It can be understood that the pressure can be the pressure directed from the first hole 600 to the cavity, and the metal layer 300 is deformed and broken in the direction of the cavity under the pressure. The pressure can also be the pressure directed from the cavity to the first hole 600, and the metal layer 300 is deformed and broken in the direction of the first hole 600 under the pressure.

[0062] Since the metal layer 300 without support will pull the metal layer 300 attached to the side wall and supported when deforming in the direction of the first hole 600, and the pulling force is in the direction away from the side wall, there is a risk that the metal layer 300 with support will also be damaged. Therefore, preferably, the metal layer 300 is damaged by the pressure directed from the first hole 600 to the cavity.

[0063] Exemplarily, the metal layer 300 can be destroyed by water pressure, air pressure or extrusion. After the destruction, the side wall can be further cleaned with a tool (for example, by scraping the edge of the side wall) to ensure that the metal layer 300 lacking support is completely removed, so that the metal layer 300 is neatly disconnected at the edge of the side wall.

[0064] Optionally, in some embodiments, after the metal layer 300 that has lost its support is destroyed, a non-conductive second filler is used to fill the first hole 600. Filling can improve the overall strength of the circuit board, and to a certain extent, can also support the suspended part after removing the first filler 400, making the structure of the circuit board more stable. The second filler is non-conductive (for example, a resin used in conventional plugging), so it will not affect the conduction design of the circuit pattern.

[0065] It can be understood that the first filler 400 can be functionally divided into two parts, wherein the first part is used to disconnect the metal layer 300 in the circumferential direction, and this part extends axially from one end of the metallized hole to the other end, and is arranged at intervals around the axis in the circumferential direction; the second part is used to disconnect the metal layer 300 in the axial direction, and this part is located between the two first parts.

[0066] In order to enable the metal layer 300 to be neatly disconnected in the circumferential direction, in some embodiments, Figure 5The first filler 400 includes a first block 410 and a second block 420, the first block 410 extends in the stacking direction and passes through multiple sub-plates, the first block 410 separates the remaining areas of the side wall in the circumferential direction, and the second block 420 is arranged between two adjacent first blocks 410, and the second block 420 separates the remaining areas of the side wall in the stacking direction.

[0067] By physically dividing the first filler 400 into a first block 410 and a second block 420, the first block 410 extends continuously in the stacking direction, so that the broken edges are more neat and there is no mutual misalignment. In addition, the first block 410 passing through multiple sub-boards can also play a positioning role, which helps to align each sub-board during pressing.

[0068] The method for making metallized holes requires removing the first filler 400 after forming the metal layer 300. On the one hand, the first filler 400 is buried in the motherboard at this time. On the other hand, the first filler 400 contacts the metal layer 300 and there is a certain bonding force between the first filler 400 and the metal layer 300. Therefore, it is not suitable to physically remove the first filler 400 by conventional window opening, otherwise the surrounding metal layer 300 will inevitably be damaged. Removing the first filler 400 by chemical corrosion is a feasible option, but this requires the use of a chemical solution that can corrode the first filler 400 but does not corrode the metal layer 300, which is difficult to implement. This is because due to the existence of the side corrosion phenomenon, if the chemical solution can corrode the metal layer 300, even if it is protected in advance, the metal layer 300 that needs to be retained will also be corroded.

[0069] In view of the above problems, in some embodiments, the first filler 400 may be removed by melting the first filler 400 at a high temperature or powdering the first filler 400 at a low temperature.

[0070] On the one hand, since melting and powdering are physical changes, no acidic or alkaline solution is needed, thus avoiding corrosion of the circuit pattern 120 or the metal layer 300. Since melting or powdering is triggered by the temperature change of the first filler 400, it is more suitable for removing the first filler 400 in a complex cavity, and will not be affected by the difficulty of solution exchange, and the efficiency and reliability of removing the first filler 400 are higher.

[0071] On the other hand, since the first filler 400 undergoes a phase change through melting and powderization, the first filler 400 can be naturally separated from the metal layer 300, and the first filler 400 does not directly contact the metal layer 300 that needs to be retained. Therefore, the impact of the separation process on the metal layer 300 that needs to be retained is further weakened, and physical damage to the metal layer 300 that needs to be retained can be avoided during removal.

[0072] In summary, compared with removing the first filler 400 by window opening or chemical etching, removing the first filler 400 by high-temperature melting or low-temperature powderization can improve efficiency and yield.

[0073] Specifically, considering that high temperature will be generated during the pressing process, in order to prevent the first filler 400 from melting during pressing and causing the glue to flow into the space originally occupied by the first filler 400 and affect the disconnection effect, the melting point of the first filler 400 should be greater than or equal to 180°C.

[0074] In the embodiment of removing the first filler 400 by high temperature melting, in order to reduce the damage to the circuit board during the melting process, the melting point of the first filler 400 should be lower than the maximum temperature that the circuit board can withstand. Exemplarily, the melting point of the first filler 400 can be selected between 210°C and 270°C.

[0075] In the embodiment of removing the first filler 400 by low temperature pulverization, in order to avoid pulverization at room temperature, the pulverization temperature of the first filler 400 should be lower than room temperature. Exemplarily, the first filler 400 can be pulverized at a temperature lower than 13.2°C.

[0076] In some embodiments, the first filler 400 includes tin (tin element or tin alloy), thereby satisfying the above requirements for the first filler 400 .

[0077] It is understandable that metallic tin has three allotropes: gray tin, white tin and brittle tin. Its Mohs hardness is only 3.75, making it one of the softest metals with good ductility but poor ductility. Within the temperature range of 13.2℃-161℃, the properties of tin are relatively stable, with a tetragonal lattice, called "white tin".

[0078] When the ambient temperature is lower than 13.2℃, the atoms in the tin crystal will rearrange and gradually change from a tetragonal lattice to a cubic lattice. This change changes the tin into a gray powder, which is "gray tin". At a temperature of -30℃, the crystal transformation speed reaches its maximum, and the tin block quickly turns into powder. The transformation from white tin to gray tin is called tin plague.

[0079] When the temperature is above 161℃, white tin turns into orthorhombic tin with orthorhombic crystal structure. Orthorhombic tin is very brittle and will break when knocked. Its brittleness increases and its ductility is poor, so it is called "brittle tin".

[0080] When the temperature is above 232°C, tin melts.

[0081] First, using tin as the first filler 400 can meet the requirements of pressing.

[0082] At the beginning of pressing, the pressure will be increased first. When it reaches the highest pressure, the temperature is about 110℃. At this time, the tin is in a stable white tin state, providing reliable support.

[0083] Thereafter, the temperature is continuously raised on the basis of constant pressure, and the fluidity of the bonding sheet 200 is further enhanced. When the temperature reaches about 140°C, the viscosity of the bonding sheet 200 is the lowest and the fluidity is the strongest. During this process, the tin can continue to remain in the state of white tin, and the hardness of the tin can withstand the squeezing force of the flowing glue, thereby effectively blocking the flowing glue and preventing the area where the first filler 400 is located from being occupied by the flowing glue.

[0084] After that, the temperature continues to rise, the viscosity of the bonding sheet 200 gradually increases, the fluidity deteriorates and solidifies, and when it reaches 160°C, the tin begins to become unstable and turns into brittle tin, but at this time the glue flow has basically entered a solidified state, and will not cause a large squeeze or other impact on the area where the tin is located (that is, the area serving as the cavity), ensuring that the area is not occupied. At the same time, since the circuit board is in a stable placement state during the hot pressing process, the first filler 400 is not impacted, so the brittle tin will not be broken and cause the glue flow to be squeezed in turn.

[0085] Continue to raise the temperature to about 200℃, the metal tin begins to soften gradually. At this time, the flow glue has solidified and will not affect the area where the tin is located.

[0086] In summary, based on the physical properties of tin, the entire pressing process will not affect the space occupied by tin, and tin as the first filler 400 can meet the requirement of endurance of the pressing process.

[0087] Secondly, tin can be removed by high temperature melting. For example, tin can be turned into liquid by heating it to slightly above 232°C. At this time, the first filler 400 only needs to be exposed to conveniently discharge the liquid tin.

[0088] Since 232° C. is only slightly higher than the temperature during lamination (eg, 200° C.), it is not easy to cause damage to the structure on the circuit board. Since liquid tin has fluidity, the complexity of the shape of the first filler 400 will not affect the discharge of the first filler 400 .

[0089] Since conventional metallized holes need to penetrate the entire circuit board, the first portion of the first filler 400 is substantially exposed on the surface of the circuit board (eg, Figure 6 The first filler 400 is shown exposed to the outside, while the second part is connected to the first part, so it can also be discharged unimpeded by fluidity.

[0090] Even if the first filler 400 is completely wrapped, the first filler 400 can be exposed by opening a hole. That is, optionally, in some embodiments, after the metal layer 300 is formed, a second hole is opened on the motherboard, the second hole exposes the first filler 400, and the first filler 400 is removed through the second hole.

[0091] The position of the second hole is not affected by the shape of the first filler 400 , and the size of the second hole is not affected by the size of the first filler 400 . Therefore, the second hole can be designed more flexibly to avoid damaging the metal layer 300 .

[0092] Finally, tin can also be removed by low-temperature powderization. Taking tin as an example, cooling to below 13.2°C can cause tin to undergo tin quenching and turn into a powder state. Cooling to below -30°C can accelerate this process. At this time, only the first filler 400 needs to be exposed to conveniently discharge the powdered tin.

[0093] It is understandable that for some temperature-sensitive circuit boards, such as those with embedded precision components, the melting temperature may exceed the tolerance of the circuit board. However, 13.2°C will hardly have a negative impact on the circuit board. The low-temperature powder removal method can better avoid the problem of damaging the circuit board and more reliably remove the first filler 400.

[0094] It should be pointed out that in the embodiments of the present application, tin is the main component of the first filler 400, but the first filler 400 is not required to be a single tin substance. It is allowed to add some other components to the first filler 400 (that is, a tin alloy that meets the requirements as the first filler 400) to adjust the physical properties of the first filler 400, as long as it does not hinder the removal of the first filler 400 by heating or cooling.

[0095] Optionally, the melting point of the first filler 400 or the temperature at which tin poisoning occurs may be adjusted by adding other components according to the needs of the process flow.

[0096] For example, if there are other low-temperature links in the process, in order to prevent the first filler 400 from being powdered prematurely, the occurrence temperature of tin pest may be reduced by adding aluminum or zinc.

[0097] Alternatively, ferromagnetic metal powder may be added to the first filler 400 so that the filler 400 can be selectively heated locally and directionally by high-frequency electromagnetic heating, thereby reducing the heat received by other areas of the circuit board during the melting process and reducing the impact on other areas.

[0098] For example, some iron powder can be sprinkled on the surface of the tin block to form the desired first filler 400; or some iron powder can be sandwiched between two tin blocks to form the desired first filler 400; or, tin can be melted in a mold, iron powder can be added and stirred evenly, and the desired first filler 400 can be formed after solidification.

[0099] Optionally, in step S170 , auxiliary means may be used to facilitate the discharge of the powdered and melted first filler 400 .

[0100] Optionally, positive pressure or negative pressure is applied to the circuit board to promote the discharge of the first filler 400. The pressure can be applied continuously or intermittently, can be always positive pressure / negative pressure, or can be applied alternately. The specific pressurization method can be determined based on the experimental results on the specific circuit board, and this application is not limited to this.

[0101] Optionally, for the cooling and removal method, since the fluidity of powder is lower than that of liquid, a solution can be injected into the area where the first filler 400 is located, and the powdered first filler 400 can be taken out with the solution to avoid residue. It should be noted that since the first filler 400 has been powdered, even if it is insoluble in the solution, it can be taken out in the form of turbid liquid, so it is not required that the first filler 400 must be soluble in the solution, but it is necessary to ensure that the solution will not react with other structures of the circuit board.

[0102] Optionally, no matter the removal is performed by increasing the temperature or decreasing the temperature, in order to avoid the first filler 400 from remaining, it is preferred that a cleaning liquid (such as deionized water) is used to clean the cavity formed after the first filler 400 is removed.

[0103] For example, a cleaning liquid may be used to apply pressure to the first hole 600 , and the cleaning liquid enters the cavity while destroying the metal layer 300 , thereby washing away the first filler 400 that may remain in the cavity.

[0104] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the application is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part described as a larger operation is performed independently.

[0105] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for making a metallized hole, characterized in that: include: Provide daughterboard; cutting a groove on the daughter board; filling the groove with a first filler; Alternately stacking the daughter boards and pressing them together to form a mother board; A first hole is opened on the motherboard, wherein the sidewall of the first hole exposes the first filler, and the first filler separates the remaining area of ​​the sidewall in the circumferential direction; forming a metal layer on a sidewall of the first hole; removing the first filler so that the metal layer formed on the surface of the first filler loses support; Pressure is applied to the metal layer to damage the metal layer without support.

2. The method for making a metallized hole according to claim 1, characterized in that: The first filler includes a first block and a second block, the first block extends in the stacking direction and passes through the plurality of sub-plates, the first block separates the remaining areas of the side walls in the circumferential direction, and the second block is arranged between two adjacent first blocks, the second block separates the remaining areas of the side walls in the stacking direction.

3. The method for making a metallized hole according to claim 1, characterized in that: After the metal layer without support is destroyed, the first hole is filled with a second non-conductive filler.

4. The method for making a metallized hole according to claim 1, characterized in that: After forming the metal layer, a second hole is opened on the motherboard, wherein the second hole exposes the first filler, and the first filler is removed through the second hole.

5. The method for making a metallized hole according to claim 1, characterized in that: The first filler is removed by melting the first filler at a high temperature or powdering the first filler at a low temperature.

6. The method for making a metallized hole according to claim 5, characterized in that: The melting point of the first filler is greater than or equal to 180°C, and the first filler has any one of the following characteristics: the melting point of the first filler is between 210°C and 270°C; the first filler can be powderized at a temperature lower than 13.2°C.

7. The method for making a metallized hole according to claim 6, characterized in that: The first filler includes tin, and the first filler is removed by any of the following methods: applying a low temperature to the area where the first filler is located to cause the first filler to be converted into powder by tinization; or applying a high temperature to the area where the first filler is located to melt the first filler.

8. A circuit board, characterized in that: The circuit board is manufactured by the metallized hole manufacturing method according to any one of claims 1 to 7.

9. A circuit board, characterized in that: include: Sub-boards, the sub-boards are arranged in a stacked manner; The metal layer extends along the stacking direction of the sub-boards to conduct the circuit patterns located in different layers. Around an axis parallel to the stacking direction, a plurality of groups of the metal layers are arranged at intervals along the circumferential direction.

10. The circuit board according to claim 9, characterized in that: A group of metal layers includes a plurality of the metal layers, and the plurality of metal layers in the same group are arranged at intervals along the stacking direction.

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