Manufacturing method of PCB blind slot air hole and PCB combination board thereof

Abstract

The invention provides a manufacturing method of a PCB blind slot air hole and a PCB combination board thereof. The manufacturing method comprises the following steps: S1, preparing an upper core board material: drilling an air hole; s2, preparing a lower core plate material; s3, prepreg materials are prepared, specifically, cutting and blind groove position hole milling are sequentially conducted on prepregs; s4, lamination: aligning the grooves or / and holes in the upper core plate, the prepregs and the lower core plate which are sequentially overlapped, filling the blind grooves of the holes milled in the prepregs with a glue blocking material through the air holes in the upper core plate, and then laminating to form a laminated piece; s5, outer layer plated-through holes are drilled in the press-fit piece, the air holes in the upper core plate are plugged, and outer layer hole metallization and outer layer pattern manufacturing are completed; s6, taking out the glue blocking material after controlled depth milling; when the blind groove is not designed at the edge of the board, the air hole can still be manufactured, only the air hole needs to be sealed on a single face in the subsequent wet manufacturing process, and the machining efficiency and the machining quality are effectively improved through process improvement.

Description

TECHNICAL FIELD

[0001] The application relates to a PCB processing technology, in particular to a manufacturing method of a PCB blind slot air hole and a PCB combined board. BACKGROUND

[0002] With the rapid development of electronic technology, electronic products are rapidly developing in the direction of miniaturization, high density, high flatness, high integration and multi-function, and the products are becoming lighter, thinner, shorter and smaller, and the requirements for printed circuit boards are becoming higher and higher. In order to arrange more components in a certain unit area and realize stronger functions, some resistors, capacitors and other components need to be embedded in the circuit board. The blind slot printed board can install various components in the blind slot area, effectively utilize the installation space, and avoid parasitic capacitance, improve the matching of impedance, and thus well realize the requirements of electronic products, so it is widely used.

[0003] In the processing technology of the blind slot printed board, when the blind slot size is large, such as more than 3.0mm*3.0mm, the blind slot is realized by using the method of pressing first and milling the blind slot opening later, due to the large size of the blind slot, the thermal stress accumulation effect generated in the lamination process (170-190℃ / 2h) and the subsequent high-temperature process (such as copper plating, solder mask curing, etc.) will cause the following failure modes: 1) thermal expansion mismatch effect, due to the formation of a local cavity structure (Cavity Structure) in the blind slot area, the thermal expansion coefficient (CTE, 50-70ppm / ℃) in the Z-axis direction is different by an order of magnitude from the adjacent dielectric layer material (CTE, 12-16ppm / ℃). According to the thermal elastic mechanics formula: σ = EαΔT / (1-ν), in the formula: σ is the thermal stress, E is the elastic modulus, α is the CTE, ΔT is the temperature difference, and v is the Poisson's ratio; when ΔT reaches 150℃, the interfacial shear stress will exceed the interlayer bonding strength (0.8-1.2kN / m) of the substrate, leading to the initiation and propagation of microcracks; 2) expansion of volatile substances, the curing reaction of the resin system during the lamination process will produce low-molecular volatile substances (mainly water vapor and amine substances), and the steam pressure (P = ρRT / M) in the closed cavity increases exponentially with the increase of temperature; experimental data shows that under the condition of 180℃, the pressure in the closed cavity can reach 1.8-2.3MPa, which exceeds the tensile strength (1.2-1.5MPa) of the glass cloth reinforced epoxy resin composite material; in view of the above failure mechanism, the current process adopts venting hole compensation design (Venting Hole Compensation) for risk control, that is, after completing the outer lamination, a venting hole is drilled in the blind slot projection area using a drill bit with a diameter of 0.3-0.5mm. For example, the patent with the publication number "CN 115087236 A" and the invention name "A manufacturing method of a high-precision blind slot board" adopts the above-mentioned conventional blind slot processing method.

[0004] However, in the existing blind slot processing mode of the printed circuit board, as shown in Figure 1 , the upper core plate 1' and the lower core plate 2' are cut respectively, then the circuit pattern is made, and then subsequent pressing is performed, then the prepreg 3' is cut, the blind slot position is milled, and then subsequent pressing is performed, then the blind slot of the prepreg is milled, the glue blocking material 4' is placed in the blind slot, and then the upper core plate 1', the lower core plate 2' and the prepreg are pressed; the board after pressing is subjected to the following processes in turn: pressing, drilling of outer metalized holes and air holes, air hole sealing, copper plating, circuit pattern making, tape tearing (the tape on the air hole is torn off), blind slot cover depth milling, and removal of the glue blocking material in the blind slot, that is, the glue blocking material is removed after the outer through-hole metalization and pattern making are completed.

[0005] In the existing blind slot processing mode of the printed circuit board, as shown in Figure 2 and Figure 3 , the blind slot is designed on the edge of the circuit board, as shown by the shaded area in the figure; when the blind slot is not designed on the edge of the circuit board, as shown in Figure 2 , the blind slot is designed in the board, and the blind slot is as shown by the shaded area in Figure 3 , the drilling of the air hole will damage the pattern at the bottom of the blind slot, at this time, the air hole cannot be made, and can only be applied to the case where the blind slot is designed on the edge, the blind slot is expanded outward by processing the spliced board, the air hole is processed in the expanded waste area, and after the air hole is processed, the air hole needs to be sealed on both sides in the subsequent wet process to avoid the air hole position entering the chemical solution. Figure 3

[0006] In summary, in the existing blind slot processing mode of the printed circuit board, when the blind slot is not designed on the edge of the circuit board, the existing processing technology is complex and difficult to control, and it is difficult to meet the needs of modern electronic products, and it is urgent to further research and improve the existing processing technology to improve the processing efficiency, reduce the processing cost, and improve the processing quality. SUMMARY

[0007] The embodiment of the present application provides a method for manufacturing a PCB blind slot air hole and a PCB combination board, the air hole is manufactured on the inner layer blind slot cover, so that the air hole does not need to penetrate the bottom of the blind slot, when the blind slot position is not designed on the edge of the board, the manufacturing of the air hole can still be realized, and since the air hole is only manufactured on the blind slot cover, it is in the form of a blind hole, only one side of the air hole is exposed, so only one side of the air hole needs to be sealed in the subsequent wet manufacturing process, thereby effectively improving the processing efficiency and the processing quality through process improvement, and reducing the processing cost.

[0008] The technical scheme adopted by the present application to solve the technical problems is as follows: The technical scheme adopted by at least one embodiment of the present application is as follows: ​In a first aspect, the application provides a manufacturing method of a PCB blind slot vent hole, comprising the following steps: S1, material preparation of the upper core plate: The upper core plate is sequentially subjected to cutting, circuit pattern manufacturing and drilling of the vent hole, and then transferred to subsequent compression; S2, material preparation of the lower core plate: The lower core plate is sequentially subjected to cutting and circuit pattern manufacturing, and then transferred to subsequent compression; S3, material preparation of the prepreg: The prepreg is sequentially subjected to cutting and milling of the blind slot position, and then transferred to subsequent compression; S4, compression: The slots and / or holes on the upper core plate, the prepreg and the lower core plate are aligned, the blind slot position of the prepreg is filled with a blocking glue material through the vent hole on the upper core plate, and then compression is performed to form a compression piece; S5, after compression, outer metalized holes are drilled on the compression piece, then the corresponding vent holes on the upper core plate are blocked, and copper is deposited to complete the outer hole metalization and outer pattern manufacturing; S6, after pattern manufacturing, the depth of the milling is controlled and the blocking glue material is removed.

[0009] Further, step S5 specifically further comprises: blocking the vent hole by attaching a PI tape.

[0010] Further, step S5 specifically further comprises: when the number of blind slots is multiple, a PI tape can be attached to the whole board, then the board surface pattern or hole is used for positioning, the board surface PI tape is cut by laser cutting, and then the excess PI tape on the board surface is removed, and the PI tape at the position of the vent hole is retained.

[0011] Further, step S5 specifically further comprises: the PI tape for blocking the vent hole is 0.5 mm larger than the single side of the vent hole, and the PI tape for blocking the vent hole is smaller than the blind slot.

[0012] In a second aspect, the application provides a PCB combination plate made by the above-mentioned manufacturing method of a PCB blind slot vent hole.

[0013] The application has the following advantages: Compared with the conventional method of drilling a vent hole after outer layer compression, the vent hole is drilled on the blind slot cover of the inner layer core plate in the application, the vent hole is in the form of a blind hole, and only one side of the vent hole needs to be blocked during the wet process, without the need for blocking on both sides, thereby saving the amount of blocking tape and improving the work efficiency.

[0014] Since the air vent hole is in the form of a blind hole, only one side of the air vent hole needs to be sealed, thus saving the amount of sealing tape and improving the work efficiency; meanwhile, the air vent hole is made before lamination, and the air vent hole can balance the pressure inside and outside the blind groove during the pressing process, thus avoiding the problem of board explosion during the pressing process.

[0015] In addition, the PI tape is first attached to the whole board, then the board surface tape is cut by laser, and then the excess tape is torn off, only leaving the tape at the air vent hole position. When the number of blind grooves is large, the efficiency of attaching the tape can be improved, and the size, formation and position accuracy of the air vent hole sealing tape are higher. Moreover, the air vent hole sealing tape is smaller than the blind groove and is located on the blind groove cover. During the subsequent depth control milling and blind groove opening process, after the blind groove cover is opened, the air vent hole and the sealing position tape will be removed together with the blind groove cover, and the air vent hole and the tape will be removed together. There is no need to separately tear off the tape at the air vent hole position. In addition, the air vent hole position is located on the blind groove cover, which belongs to the waste area and does not penetrate the bottom of the blind groove. When the blind groove is not designed on the edge of the shape, it can still be made. When the blind groove is located on the edge of the board, there is no need to expand a large space to provide a drilling air vent hole, which can reduce the area of the waste area and improve the utilization rate of the material panel.

[0016] The application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a process flow diagram of the air vent hole processing of the blind groove on the PCB in the prior art; Figure 2 is a structure diagram of the blind groove designed on the edge of the circuit board in the prior art; Figure 3 is a structure diagram of the blind groove designed in the circuit board in the prior art; Figure 4 is a process flow diagram of the air vent hole processing of the blind groove on the PCB in the prior art. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0019] In the description of the present application, the meaning of one or more is one or more, the meaning of multiple is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If the terms "center", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", etc. appear, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0020] In addition, in the description of the present application, unless otherwise explicitly limited, the words such as setting, mounting, connecting, etc. should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above words in the present application can be reasonably determined in combination with the specific content of the technical solution.

[0021] A PCB blind slot vent hole manufacturing method, as shown in Figure 4 The PCB blind slot vent hole manufacturing method comprises the following steps: S1, upper core plate material preparation: The upper core plate 1 is sequentially subjected to cutting, circuit pattern making and drilling of vent holes, and then transferred to subsequent pressing; S2, lower core plate material preparation: The lower core plate 2 is sequentially subjected to cutting and circuit pattern making, and then transferred to subsequent pressing; S3, prepreg material preparation: The prepreg 3 is sequentially subjected to cutting and blind slot position hole milling, and then transferred to subsequent pressing; S4, pressing: The slots and / or holes on the upper core plate, the prepreg and the lower core plate are aligned, the blind slot position of the prepreg is filled with a blocking glue material through the vent hole on the upper core plate, and then the pressing is performed to form a pressing piece; S5, after pressing, first drill outer metalized holes on the pressing piece, then block the corresponding vent holes on the upper core plate, and then sink copper to complete the outer hole metalization and outer pattern making; In step S5, the air vent is sealed by sticking PI tape or the like. When the number of blind grooves is large, the PI tape can be stuck on the whole board, and then the board surface pattern or hole is used for positioning, the PI tape on the board surface is cut by laser cutting, and then the excess PI tape on the board surface is removed, and the PI tape at the air vent position is retained. Meanwhile, the PI tape sealing the air vent is about 0.5 mm larger than the single side of the air vent, and the PI tape sealing the air vent is smaller than the blind groove. S6, after the pattern is made, the depth control milling is performed, and then the blocking material is removed.

[0022] Compared with the existing conventional outer layer pressing and then drilling air vents, the air vent is drilled on the blind groove cover of the inner layer core plate in this embodiment, the air vent is in the form of a blind hole, and only one side of the air vent needs to be sealed in the wet process, without the need for sealing on both sides, thereby saving the amount of sealing tape and improving the work efficiency. Since the air vent is in the form of a blind hole, only one side of the air vent needs to be sealed, thereby saving the amount of sealing tape and improving the work efficiency. Meanwhile, the air vent is made before lamination, and the air vent can balance the pressure inside and outside the blind groove during the pressing process, thereby avoiding the problem of board explosion during the pressing process.

[0023] Moreover, the air vent position is located on the blind groove cover, which belongs to the waste area and does not penetrate the bottom of the blind groove. When the blind groove is not designed on the outer shape edge, the air vent can still be made. After the blind groove cover is opened, the tape at the air vent and sealing position is removed together with the blind groove cover, without the need for separately removing the tape at the air vent position.

[0024] Meanwhile, before the wet process, the outer layer is sealed by sticking PI tape or the like. When the number of blind grooves is large, the tape can be stuck on the whole board, and then the board surface pattern or hole is used for positioning, the tape on the board surface is cut by laser cutting, and then the excess tape on the board surface is removed, and the tape at the air vent position is retained, thereby improving the efficiency of sticking the tape, and the size, formation and position accuracy of the tape sealing the air vent are high. The above-described embodiments are only the preferred embodiments of the present application, and do not limit the implementation range of the present application. Except for the cases listed in the specific embodiments, equivalent changes made according to the method and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for manufacturing a PCB blind slot vent, characterized in that, The manufacturing method comprises the following steps: S1, core plate material preparation: The upper core plate is sequentially subjected to cutting, circuit pattern manufacturing and drilling of air holes, and then is transferred to subsequent pressing; S2, lower core plate material preparation: The lower core plate is sequentially subjected to cutting and circuit pattern manufacturing, and then is transferred to subsequent pressing; S3, prepreg material preparation: The prepreg is sequentially subjected to cutting and blind slot position hole milling, and then is transferred to subsequent pressing; S4, pressing: The slots and / or holes on the upper core plate, the prepreg and the lower core plate which are sequentially stacked are aligned, the blind slot position hole-milled prepreg is filled with blocking glue material through the air holes on the upper core plate, and then the prepreg is pressed to form a pressed part; S5, after pressing, the pressed part is drilled with outer layer metallization holes, then the corresponding air holes on the upper core plate are blocked, and copper is deposited to complete outer layer hole metallization and outer layer pattern manufacturing; S6, after pattern manufacturing, the depth of the prepreg is controlled and the prepreg is removed.

2. The method of claim 1, wherein, In step S5, the air holes are further blocked by PI tape.

3. The method of claim 2, wherein the method further comprises: In step S5, when the number of blind slots is multiple, the PI tape can be attached to the whole board, then the board surface pattern or hole is used for positioning, the board surface PI tape is cut by laser cutting, and then the excess PI tape on the board surface is removed, and the PI tape at the air hole position is reserved.

4. The method of claim 2, wherein the method further comprises: In step S5, the PI tape for blocking the air holes is 0.5 mm larger than the single side of the air holes, and the PI tape for blocking the air holes is smaller than the blind slots.

5. A PCB bonding plate characterized by, The PCB bonding plate is made by the manufacturing method of the PCB blind slot air hole according to any one of claims 1-4.

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