A method for manufacturing a stepped groove bottom pattern

Abstract

The application discloses a kind of ladder groove bottom pattern manufacturing method and PCB, comprising the following steps: S10, provide first subboard as the subboard of ladder groove layer, the first subboard and the surface layer of corresponding ladder groove bottom unprocessed line pattern, the first subboard is plated with copper S20 as a whole, process the groove bottom circuit pattern corresponding to the preset ladder groove of the first subboard;S30, provide other layer subboard and prepreg, and press together with the first subboard, manufacture the mother plate with ladder groove;S40, to the ladder groove plating chemical copper;S50, to the ladder groove is micro-etched, remove the chemical copper in the ladder groove.The groove bottom circuit pattern of the application is plated with copper first, then plating chemical copper, and chemical plating is used as the to-be-removed layer of the groove bottom circuit pattern surface that can be accurately controlled removal amount, thereby high-precision groove bottom circuit pattern manufacturing can be realized, and copper layer on the side wall of ladder groove does not need secondary mechanical processing to remove, process is simple, high yield, no bottleneck of output.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of PCB manufacturing, in particular to a method for manufacturing a stepped groove bottom pattern. BACKGROUND

[0002] With the miniaturization and lightness of electronic products, the product circuit design is more delicate, and some products need to carry more accessories to meet the demand for high-speed transmission, such as switches. Since the conventional connectors are standard, it is difficult to install the required accessories on the same board to meet the speed of 400G / s. Therefore, the design of the PCB board is improved, such as designing a stepped groove to meet the connection of the required accessories. However, the manufacturing process of the PCB stepped groove is very complex, as it needs to be connected to other accessories, the groove bottom usually has a crimp hole and a pattern design, and the conventional PCB equipment cannot achieve high-precision pattern manufacturing of a certain depth of the groove bottom.

[0003] The current industry solutions to the above problems for such products are as follows:

[0004] 1. One-time pressing + laser soldering method, this method mainly relies on laser ablation to make patterns, but the pattern accuracy cannot meet the requirements, only 5.0 ± 0.5 mil can be achieved, and it is not suitable for manufacturing high-precision circuit patterns, and it involves high-performance laser equipment, which exists output bottleneck.

[0005] 2. One-time pressing + inkjet tin blocking method, this method has more processes, the accuracy of the inkjet pattern is limited, and it also needs to be ablated by laser. This method cannot confirm whether the excess ink is ablated clean by laser, and it is easy to produce ink residue, which will cause tin plating defects when the pattern is electroplated, finally leading to groove bottom pattern etching bite or open circuit defects. It is also not suitable for manufacturing high-precision patterns, and the accuracy can only be achieved to 5.0 ± 0.5 mil, and it involves high-performance laser equipment, which exists output bottleneck.

[0006] 3. Two-time pressing + tape sticking method, this method first makes patterns on the sub-board, then protects the patterns with a pad or tape for secondary pressing, and also uses the tape sticking method to protect the groove bottom pattern before electroplating the mother board. After completing the pattern of the mother board, the tape is removed to expose the groove bottom pattern. However, the tape cannot withstand strong alkali and high temperature during the chemical glue removal process of the mother board, and it is easy to fall off, which will damage the groove bottom pattern and reduce the yield.

[0007] 4. The method uses twice pressing + low flow adhesive protection method, which first makes the pattern of the sub-plate, then protects the pattern by using the cushion or adhesive tape method for twice pressing, during the second pressing, the low flow adhesive is used for surface pressing protection of the stepped groove, and after the completion of the mother plate pattern, the PP surface layer is removed to expose the groove bottom pattern. However, this method uses low flow adhesive, which has weak bonding force with the copper layer. Similarly, when the mother plate is subjected to chemical degreasing process, the PP is prone to crack with the copper surface, which leads to the entry of chemical into the stepped groove, the pattern is damaged, the yield is low, and the low flow adhesive at the end of the method needs to be removed by mechanical milling, which occupies a large space of the customer's product.

[0008] The above methods all have certain disadvantages and cannot simultaneously meet high pattern accuracy and high yield. SUMMARY

[0009] The present application aims to provide a stepped groove bottom pattern manufacturing method to solve one or more technical problems in the prior art and at least provide a beneficial option or create conditions.

[0010] To solve the above technical problems, the technical solution adopted is:

[0011] The present application provides a stepped groove bottom pattern manufacturing method, comprising the following steps:

[0012] S10. Providing a first sub-plate as a sub-plate of the stepped groove layer, the first sub-plate corresponding to the surface layer unprocessed line pattern of the stepped groove bottom, and the first sub-plate is plated with flash copper as a whole;

[0013] S20. Processing the groove bottom circuit pattern of the first sub-plate corresponding to the preset stepped groove;

[0014] S30. Providing other layer sub-plates and prepreg, and pressing with the first sub-plate to manufacture a mother plate with a stepped groove;

[0015] S40. Plating chemical copper on the stepped groove;

[0016] S50. Micro-etching the stepped groove to remove the chemical copper in the stepped groove.

[0017] The beneficial effects of the present application are: compared with the prior art, the technical solution of the present application first plates the sub-plate with dense and thick flash copper, then etches the groove bottom circuit pattern, and then plates the chemical copper with loose texture and thin thickness, the chemical plating is used as the to-be-removed layer with accurate control of the removal amount of the surface of the groove bottom circuit pattern, thereby realizing high-precision groove bottom circuit pattern manufacturing, without the need for secondary mechanical processing to remove the copper layer of the stepped groove sidewall, the process is simple, the yield is high, and there is no output bottleneck.

[0018] As a further improvement of the above technical solution, in step S10, a through hole is drilled before the flash plating of the sub-plate. Some stepped slots need to be provided with through holes. When there are through holes, drilling is needed before the flash plating of the sub-plate, so that the through holes are also plated with a layer of flash-plated copper. In this way, when the through holes are subjected to micro-etching together with the slot bottom circuit pattern of the stepped slot in the subsequent process, the copper layer on the inner wall of the through hole will not be completely etched by the micro-etching solution.

[0019] As a further improvement of the above technical solution, in step S20, the first sub-plate is used to form the slot bottom circuit pattern through film pasting, exposure, development, etching, and film stripping. The areas corresponding to the slot bottom circuit pattern and the through hole are retained during the development of the sub-plate. In this way, the flash-plated copper in the through hole is protected from being damaged during the production of the slot bottom circuit pattern.

[0020] As a further improvement of the above technical solution, in step S30, the formation of the stepped slot includes: providing an upper sub-plate and a lower sub-plate located above and below the first sub-plate respectively, windowing the upper sub-plate corresponding to the positions of the preset stepped slots, windowing the prepreg corresponding to the windowed sub-plate, and then stacking the upper sub-plate, the first sub-plate, the lower sub-plate, and the prepreg. A pad is placed at the windowed position, and after pressing, the pad is removed to form the stepped slot.

[0021] As a further improvement of the above technical solution, in step S40, before the chemical copper plating of the stepped slot, a via hole is drilled on the mother plate. The via hole is provided on the mother plate, and the via hole is plated with copper simultaneously with the stepped slot before the chemical copper plating of the stepped slot.

[0022] As a further improvement of the above technical solution, the entire mother plate is plated with chemical copper, so that the stepped slot and the via hole are both plated with chemical copper.

[0023] As a further improvement of the above technical solution, the micro-etching production step includes: covering the outer surface of the mother plate drilled with the via hole with a protective film, uncovering the protective film to expose the stepped slot, and then performing overall micro-etching on the mother plate by using a micro-etching solution. After protecting the via hole with a protective film, only the inner part of the stepped slot is subjected to micro-etching. By controlling the concentration of the micro-etching solution, the thickness of the chemical copper of the slot bottom circuit pattern can be accurately removed.

[0024] As a further improvement of the above technical solution, the thickness of the flash-plated copper ranges from 5 to 10 μm, and the thickness of the chemical copper ranges from 0.35 to 0.75 μm.

[0025] As a further improvement of the above technical solution, the micro-etching amount of the micro-etching step is controlled to be in the range of 1.0-1.5 μm by controlling the concentration of the micro-etching solution. After micro-etching in this range, the residual copper thickness of the groove bottom circuit pattern is 3.85-9.75 μm, which is much greater than the conventional chemical copper thickness and is sufficient for the electroplating thickening of the copper conductor of the mother board.

[0026] As a further improvement of the above technical solution, the copper of the mother board is electroplated and thickened after step S50. The electroplated and thickened copper can form a dense electroplated layer on the whole board, thereby ensuring the reliable quality and reliability of the final product. For the groove bottom pattern, the electroplated and thickened copper of the whole mother board does not cause a large copper thickness difference due to the pattern difference, so that the pattern is not uniform. When the outer pattern of the mother board is made, no copper is plated and only tin is plated. Since the groove bottom pattern has been made, the side of the pattern circuit is plated with tin and is protected. Therefore, the groove bottom pattern does not have the side etching problem in the conventional process, and the pattern accuracy of the groove bottom is completely ensured. BRIEF DESCRIPTION OF DRAWINGS

[0027] The present application will be further described below in conjunction with the drawings and examples;

[0028] Figure 1 is a structural schematic view of the first sub-board corresponding to the stepped groove position of Example 1 of the present application;

[0029] Figure 2 is Figure 1 a structural schematic view of the first sub-board after electroplating and flash plating copper;

[0030] Figure 3 is Figure 2 a structural schematic view of the first sub-board after electroplating and making groove bottom circuit pattern;

[0031] Figure 4 is a structural schematic view of the mother board after forming the stepped groove of Example 1 of the present application;

[0032] Figure 5 is Figure 4 a structural schematic view of the mother board after electroplating chemical copper;

[0033] Figure 6 is Figure 5 a structural schematic view of the mother board after micro-etching. DETAILED DESCRIPTION

[0034] This part will describe the specific embodiments of the present application in detail. The preferred embodiments of the present application are shown in the drawings, which serve to supplement the description in the text part of the specification and enable people to intuitively and visually understand each technical feature and the overall technical solution of the present application, but cannot be understood as a limitation on the protection scope of the present application.

[0035] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by the upper, lower, front, rear, left, right and the like, is based on the orientation or position 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 device or element referred to 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.

[0036] In the description of the present application, greater than, less than, more than, etc. are understood as not including the number, and above, below, etc. are understood as including the number. If the first, second is described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the sequence of technical features indicated.

[0037] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting and the like should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0038] Embodiment 1:

[0039] Referring to Figures 1-3 The method for manufacturing the bottom pattern of the stepped slot is described, which comprises:

[0040] Step S10, providing a first sub-plate 100 as a sub-plate of the stepped slot layer, the first sub-plate corresponding to the surface layer of the bottom of the stepped slot, then drilling a through hole 110 at the position corresponding to the preset stepped slot of the first sub-plate 100, and then flash plating the first sub-plate 100 as a whole. The number of through holes 110 is set according to the actual situation.

[0041] Referring to Figure 2 After flash plating, the upper surface, the lower surface and the inner wall of the through hole 110 of the first sub-plate 100 are covered with a layer of flash plated copper 120. The thickness of the flash plated copper is in the range of 5-10 μm.

[0042] The through hole 110 is drilled first and then flash plated in order to make the inside of the through hole 110 first electroplated with a layer of copper. In this way, when the through hole 110 is microetched together with the slot bottom circuit pattern in the subsequent process, the copper layer on the inner wall of the through hole 110 will not be completely etched by the microetching liquid, avoiding the phenomenon of no copper in the hole.

[0043] Among them, the first sub-plate 100 can be a core plate, or a plurality of core plates pressed together. The following will take the first sub-plate 100 shown in Figure 1 to illustrate the manufacturing steps when the first sub-plate 100 is pressed together from a plurality of core plates.

[0044] Figure 1The first sub-board 100 is pressed from two core boards, and the processing steps of the first sub-board 100 include core board cutting, inner layer dry film pretreatment, inner layer DI exposure, inner layer development, inner layer etching, inner layer film stripping, inner layer AOI, core board matching, brown, and pressing into a sub-board. The inner layer DI exposure refers to making inner layer circuit patterns on the inner layer core board at positions other than the non-step groove layer, for example. Figure 1 As shown, no circuit pattern is made on the L1 layer, circuit patterns are made on the L2 layer and the L3 layer, and circuit patterns are made or not made on the L4 layer as needed. The circuit pattern of the L1 layer is made after the first sub-board 100 is flash plated.

[0045] In step S20, the outer layer circuit pattern of the first sub-board 100 is processed to form a groove bottom circuit pattern 101 corresponding to the preset step groove, that is, the circuit pattern of the L1 layer is made.

[0046] The processing steps of the groove bottom circuit pattern 101 include sub-board film pasting, sub-board exposure, sub-board development, sub-board etching, and sub-board film stripping. In the sub-board development, the groove bottom circuit pattern 101 and the through hole 110 area are reserved, so that the inner wall of the through hole 110 and the outer layer of the groove bottom circuit pattern 101 are both flash plated copper after the film stripping.

[0047] In step S30, other layer sub-boards and prepregs are provided, and are pressed with the first sub-board 100 to make a master board 200 with a step groove 210.

[0048] The processing steps of the step groove include providing an upper layer sub-board and a lower layer sub-board respectively above and below the first sub-board 100, and a prepreg, cutting a window in all or part of the upper layer sub-board corresponding to the preset step groove, cutting a window in the prepreg corresponding to the cut sub-board, and then stacking the upper layer sub-board, the first sub-board 100, the lower layer sub-board, and the prepreg, and making the step groove by filling a pad layer in the cut position or embedding a pad layer, to form a master board with a step groove as shown. Figure 4

[0049] The method for making the step groove by embedding the pad layer is that the upper layer sub-board in the inner layer of the master board is cut, that is, the upper layer sub-board in the outermost layer of the master board is not cut, and the pad layer is embedded in the groove formed by each cut when the sub-boards are stacked, and the upper layer sub-board in the outermost layer of the master board is opened after lamination, and the pad layer is taken out, so as to form the step groove.

[0050] The method for making the step groove by filling the pad layer is that all the upper layer sub-boards are cut, and the pad layer is filled in the groove formed by each cut after the sub-boards are stacked, and the buffer plate is placed on the upper surface of the master board before lamination, the buffer plate is removed after lamination, and the pad layer is taken out, so as to form the step groove.

[0051] ​Further, the cushion layer comprises a PTFE gasket and a tape arranged in a stack from top to bottom, the PTFE gasket is used to prevent the semi-cured sheet from melting into the groove bottom during pressing, and the tape is used to protect the groove bottom circuit pattern from sticking to the PP powder.

[0052] In step S40, the mother board 200 is drilled through the holes 220, and then the whole mother board 200 is plated with chemical copper. The number of the holes 220 is set according to actual conditions.

[0053] With reference to Figure 5 After the chemical copper plating, the upper surface and the lower surface of the mother board 200, the side wall and the bottom wall of the stepped groove 210, and the inner wall of the through hole 110 and the inner wall of the via hole 220 are plated with chemical copper, and the thickness of the chemical copper ranges from 0.35 to 0.75 μm.

[0054] After the chemical copper plating, the inner wall of the through hole 110 and the groove bottom circuit pattern 101 are additionally plated with a layer of chemical copper on the outer layer of the flash copper, and the inner wall of the via hole 220 is only plated with a layer of chemical copper.

[0055] In step S50, the stepped groove 210 is micro-etched to remove the chemical copper 230 in the stepped groove 210.

[0056] The manufacturing steps of the micro-etching include: covering the outer surface of the mother board 200 with the via holes 220 with a protective film, uncovering the areas of the stepped groove 210 of the protective film to expose the stepped groove 210, and then micro-etching the whole mother board 200 through a micro-etching solution. The micro-etching amount can be accurately controlled by controlling the concentration of the micro-etching solution. In this embodiment, according to the thickness of the chemical copper, the micro-etching amount is controlled in the range of 1.0 to 1.5 μm. Further, the protective film can be a dry film or a blue glue. Since the blue glue has a lower cost, the blue glue is preferably used as the protective film.

[0057] Since the outer surface of the mother board 200 is covered with the protective film, the chemical copper of the via hole 220 is kept intact, and only the side wall and the bottom wall of the stepped groove 210 and the through hole 110 are micro-etched by the micro-etching solution. The main purpose of the micro-etching of the mother board is to remove the chemical copper of the exposed groove bottom of the stepped groove, and the high-precision groove bottom circuit pattern 101 is manufactured through the accurate control of the micro-etching amount.

[0058] It should be noted that the chemical copper is formed by displacement reaction, and the chemical reaction is completed in a relatively short time, so the chemical copper is loose and thin; the flash-plated copper is formed by electrolysis, and the electrolysis reaction time is relatively long, and the electrolysis characteristics determine that the flash-plated copper is dense, and the copper layer formed by the flash-plated copper is relatively thick. Therefore, the chemical copper is easily removed under the action of the micro-etching solution, and the flash-plated copper is not easily removed. By using this characteristic, the embodiment adopts the chemical plating as the to-be-removed layer of the slot bottom circuit pattern 101 surface which can be accurately controlled to be removed. After the step S50 is completed, the thickness of the slot bottom circuit pattern 101 is realized to be high-precision, and at the same time, the chemical copper in the inner wall of the via hole 220 is well reserved, and at the same time, the copper layer on the sidewall of the stepped slot is removed. Compared with the prior art, this manufacturing method is simple in process, can manufacture a high-precision slot bottom circuit pattern, for example, can satisfy the requirement of 2.5±0.5 mil pattern precision, does not need secondary mechanical processing to remove the copper layer on the sidewall of the stepped slot, has no output bottleneck, and has a high yield.

[0059] In the embodiment, the thickness of the flash-plated copper ranges from 5 to 10 μm, the thickness of the chemical copper ranges from 0.35 to 0.75 μm, the micro-etching amount ranges from 1.0 to 1.5 μm, and after the mother board is micro-etched, the thickness of the flash-plated copper remaining in the via hole 110 and the slot bottom circuit pattern 101 can range from 3.85 to 9.75 μm, and the flash-plated copper in this thickness range is sufficient to serve as a mother board for electroplating and thickening copper.

[0060] Step S60, electroplating and thickening copper on the mother board 200.

[0061] After micro-etching by the micro-etching solution, the slot bottom circuit pattern 101 and other positions can be normally electroplated and thickened when the mother board is electroplated and thickened, and the electroplated and thickened copper can form a dense electroplated layer on the whole board, thereby ensuring the reliable conduction quality and reliability of the final product. After the protective film covering the outer surface of the mother board 200 is removed, electroplating and thickening copper can be performed. For the slot bottom pattern, at this time, the electroplating and thickening of the whole mother board does not exist, and the copper thickness difference caused by the pattern difference is large, so that the pattern is not uniform. In subsequent production of the outer layer pattern of the mother board, only tin is plated without copper, and the sidewall of the pattern line is also plated with tin and protected, so that the slot bottom pattern does not have the side etching problem in the traditional process, and the pattern precision of the slot bottom is completely ensured.

[0062] Embodiment 2:

[0063] The difference between Embodiment 2 and Embodiment 1 is that no via hole 110 is arranged below the stepped slot in Embodiment 2, and correspondingly, the step S10 does not need to drill a via hole on the first sub-board 100. The step S10 of Embodiment 2 is to provide the first sub-board 100 as the sub-board of the stepped slot layer, and to flash-plate the first sub-board 100 as a whole.

[0064] Embodiment 3:

[0065] The difference between the embodiment 3 and the embodiment 1 is that when the step S40 is performed, the mother board 200 is not drilled through holes 220 before the whole chemical copper plating of the mother board 200, and the drilling and copper plating of the through holes 220 can also be performed separately in the subsequent process. This way has more processes than the embodiment 1.

[0066] Since there is no through hole 220, when the chemical copper plating is performed, the whole chemical copper plating of the mother board 200 can be performed, or the film is covered on the upper surface and the lower surface of the mother board, and only the stepped groove 210 is plated with chemical copper. The whole chemical copper plating of the mother board 200 in the embodiment 1 is because the mother board has the drilled through hole 220 before the chemical copper plating, in order to make the through hole 220 also be plated with chemical copper so as to be subsequently electroplated with thick copper, and therefore the upper surface and the lower surface of the mother board are not covered with the film and are plated with the whole copper.

[0067] The above describes the preferred embodiments of the present application, but the present application is not limited to the embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A method for manufacturing a stepped groove bottom pattern, characterized in that, The method comprises the following steps: S10, providing a first sub-board (100) as a sub-board of a stepped groove layer, a surface layer of the first sub-board (100) corresponding to a non-processed line pattern of a stepped groove bottom, and the first sub-board (100) being entirely plated with flash copper (120); S20, processing a groove bottom line pattern (101) of the first sub-board (100) corresponding to a preset stepped groove; S30, providing other layer sub-boards and prepregs, and pressing the first sub-board (100) to manufacture a master board (200) with a stepped groove (210); S40, entirely plating the stepped groove (210) with chemical copper (230), and the thickness of the chemical copper being less than that of the flash copper; S50, performing micro-etching on the stepped groove (210) to remove the chemical copper (230) in the stepped groove (210).

2. The method of claim 1, wherein the step of forming the stepped trench bottom pattern is performed by a method comprising: In step S10, the through hole (110) is drilled before the sub-board (100) is flash plated.

3. The method of claim 2, wherein the step of forming the stepped bottom pattern is performed by a process of etching the substrate. In step S20, the first sub-board (100) forms the groove bottom line pattern (101) through film pasting, exposure, development, etching and film stripping, and the areas corresponding to the groove bottom line pattern (101) and the through hole (110) are reserved during sub-board development.

4. The method of claim 1, wherein: In step S30, the forming step of the stepped groove (210) comprises the following steps: providing an upper layer sub-board and a lower layer sub-board located above and below the first sub-board (100) respectively, opening a window on the upper layer sub-board corresponding to the position of the preset stepped groove, opening a window on the prepreg corresponding to the windowed sub-board, and then stacking the upper layer sub-board, the first sub-board (100), the lower layer sub-board and the prepreg, placing a pad at the windowed position, and removing the pad after pressing to form the stepped groove.

5. The method of claim 1, wherein the step of forming the stepped trench bottom pattern is performed by a method comprising: In step S40, a through hole (220) is drilled on the master board (200) before the stepped groove (210) is plated with chemical copper.

6. The method of claim 5, wherein the step of forming the stepped trench bottom pattern is performed by a method comprising: The master board (200) is entirely plated with chemical copper, and the stepped groove (210) and the through hole (220) are both plated with chemical copper.

7. The method of claim 6, wherein: The micro-etching manufacturing step comprises the following steps: covering the outer surface of the master board (200) drilled with the through hole (220) with a protective film, uncovering the protective film to expose the stepped groove (210), and then performing overall micro-etching on the master board (200) through a micro-etching solution.

8. The method of claim 1, wherein: The thickness of the flash copper (120) ranges from 5 to 10 μm, and the thickness of the chemical copper (230) ranges from 0.35 to 0.75 μm.

9. The method of claim 8, wherein: The micro-etching amount of the micro-etching step ranges from 1.0 to 1.5 μm by controlling the concentration of the micro-etching solution.

10. The method of claim 1, wherein: After step S50, the master board (200) is electroplated with thickened copper.

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