Method for realizing step pattern printed circuit board

Abstract

The invention relates to a method for realizing a step pattern printed circuit board, which comprises the following steps of: drilling a hole on a laminated circuit board, then forming a step groove, and carrying out electroplating operation; performing electrostatic spraying of an electroplating resist on the bottom of the stepped groove to form a stepped groove area; performing pattern electroplating on a non-stepped groove area except the stepped groove area to realize pattern transfer of the non-stepped groove area; removing the electroplating resist at the bottom of the stepped groove, and performing circuit pattern etching on the stepped groove area and the non-stepped groove area; and obtaining the step pattern printed circuit board after a detection program. According to the method for realizing the stepped pattern printed circuit board, the groove bottom of the stepped groove of the multi-layer circuit board is coated with the electroplating resistance agent in an electrostatic coating mode, the stepped groove pattern is realized by using a coating process, and the electroplating resistance agent is used as a pattern transfer medium to replace a dry film to realize the pattern transfer requirement of the bottom of the stepped groove; and the step pattern design of the printed circuit board is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of production methods of printed circuit boards, and particularly to an electrostatic spraying method for realizing a stepped pattern printed circuit board. Background Art

[0002] With the development of AI servers and data networks towards higher speeds, the increase in the rate of serdes (deserializer), and the increasing requirements for data processing capabilities of high-speed products, PCBs need to carry higher-frequency and higher-speed signal transmissions. For example, the speed is increased from 800G to 1.6T, which leads to an increase in the number of PCB layers and board thickness. To reduce the connector plug-in space at the client side, meet the requirements of the cabinet slot pitch, and ensure that the number of cabinet trays is not affected, it is necessary to limit the thickness of the I / O connection area. To meet the increase in component space without affecting the number of cabinet trays, and at the same time, as the serdes rate increases, the thicker the board thickness, the longer the signal transmission path, and the increase in SI loss (SI loss refers to the signal energy loss caused by the insulation characteristics of materials in high-speed digital systems), etc. Under such harsh conditions, the traditional PCB structure is increasingly unable to meet the requirements. To shorten the transmission path, designing a stepped pattern on the PCB is beneficial to improving the SI level of high-speed I / O signals.

[0003] From the perspective of the stack-up design, the pattern at the bottom of the stepped groove cannot be fabricated in advance on the inner layer because there is a need for electroplated vias after the outer layer is grooved, and the pattern transfer at the bottom of the stepped groove must be achieved on the outer layer. Due to the existence of the stepped depth, it is impossible to achieve the pattern transfer function at the bottom of the stepped groove through normal film pressing, nor can the stepped pattern design of the printed circuit board be achieved through conventional production processes. Summary of the Invention

[0004] Based on this, it is necessary to provide a method for realizing a stepped pattern printed circuit board for at least one of the above-mentioned problems.

[0005] The method for realizing a stepped pattern printed circuit board provided by the present invention includes the following steps:

[0006] Drill holes in the pressed circuit board to form stepped grooves, and perform electroplating operations;

[0007] Electrostatically spray an electroplating resist on the bottom of the stepped groove to form a stepped groove area;

[0008] For the non-stepped groove area outside the stepped groove area, perform pattern electroplating to achieve pattern transfer in the non-stepped groove area;

[0009] Remove the electroplating resist at the bottom of the stepped groove, and etch the circuit patterns in the stepped groove area and the non-stepped groove area;

[0010] After the detection process, a stepped pattern printed circuit board is obtained.

[0011] In one embodiment, the step of drilling stepped grooves on the pressed circuit board includes:

[0012] Set polypropylene between the circuit boards, and after setting tapes in the areas corresponding to the stepped grooves, press the circuit boards.

[0013] In one embodiment, the step of drilling stepped grooves on the pressed circuit board includes:

[0014] When the process of electroplating on the filled conductive vias is not required, drill all the copper deposition holes on the pressed circuit board at one time.

[0015] In one embodiment, the step of performing graphic electroplating to achieve graphic transfer in the non-stepped groove area includes:

[0016] Achieve graphic transfer in the non-stepped groove area through laminating, exposure, development, secondary electroplating, and tin-lead plating.

[0017] In one embodiment, in the step after the detection process, the detection process includes: automatic optical inspection, formed electrical test, and appearance inspection.

[0018] In one embodiment, in the step after the detection process, it further includes: after the automatic optical inspection, apply ink to the bottom of the stepped groove.

[0019] In one embodiment, the steps of removing the electroplating resist on the bottom of the stepped groove and etching the circuit pattern in the stepped groove area and the non-stepped groove area successively include: removing the dry film, using laser ablation to remove the electroplating resist in the stepped groove area, using plasma to remove the remaining electroplating resist, sandblasting to remove oxidation, and etching the circuit pattern.

[0020] The technical solutions provided in the embodiments of the present invention bring the following beneficial technical effects:

[0021] The method for realizing a stepped pattern printed circuit board provided by the present invention coats an electroplating resist on the bottom of the stepped groove of a multi-layer circuit board by means of electrostatic coating, uses the coating process to realize the stepped groove pattern, uses the electroplating resist as the medium for graphic transfer, replaces the dry film to meet the graphic transfer requirements at the bottom of the stepped groove, and realizes the stepped pattern design of the printed circuit board.

[0022] The additional aspects and advantages of this application will be given in the subsequent parts, and will be understood in detail from the subsequent description, or learned through the specific implementation of the present invention. Description of the Drawings

[0023] Figure 1 This is a flowchart of a method for implementing a stepped pattern printed circuit board in an embodiment of the present invention;

[0024] Figure 2 This is a schematic structural diagram of a stepped pattern printed circuit board in an embodiment of the present invention;

[0025] Figure 3 This is a schematic structural diagram of each process for implementing a stepped pattern printed circuit board in an embodiment of the present invention. Detailed implementation manners

[0026] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The possible embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein with reference to the drawings. The embodiments described by referring to the drawings are exemplary and are used to make the understanding of the disclosure of the present invention more thorough and comprehensive, and should not be construed as a limitation of the present invention. In addition, if the detailed description of the known technology is not necessary for showing the features of the present invention, these technical details may be omitted.

[0027] Those skilled in the relevant art can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the technical field to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as here.

[0028] Those skilled in the technical field of the present invention can understand that unless specifically stated, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application means the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their groups. It should be understood that the phrase "and / or" used herein includes all or any unit and all combinations of one or more of the associated listed items.

[0029] From the perspective of the stack-up design, the pattern at the bottom of the stepped groove cannot be made in advance on the inner layer because there is a need for electroplated PTH after the outer layer is grooved, and the pattern transfer at the bottom of the stepped groove must be achieved on the outer layer. Due to the existence of the stepped depth, the transfer function of the pattern at the bottom of the stepped groove cannot be achieved by normal film pressing, that is, the stepped pattern design cannot be achieved by traditional production processes.

[0030] The following uses specific embodiments to elaborate in detail on the technical solution of the present invention and how this technical solution solves the above-mentioned technical problems.

[0031] The method for implementing a stepped pattern printed circuit board provided by the present invention, as Figure 1 shown, includes the following steps:

[0032] S100: After drilling holes in the pressed circuit board, a stepped groove is opened, and electroplating operation is carried out.

[0033] S200: Electrostatic spraying of electroplating resist is carried out on the bottom of the stepped groove to form a stepped groove area.

[0034] S300: For the non-stepped groove area outside the stepped groove area, pattern electroplating is carried out to realize the pattern transfer of the non-stepped groove area.

[0035] S400: The electroplating resist at the bottom of the stepped groove is removed, and circuit pattern etching is carried out on the stepped groove area and the non-stepped groove area.

[0036] S500: After passing the detection program, a stepped pattern printed circuit board is obtained.

[0037] The method for implementing a stepped pattern printed circuit board provided by the present invention coats electroplating resist on the bottom of the stepped groove of a multi-layer circuit board by means of electrostatic coating, uses the coating process to realize the stepped groove pattern, takes the electroplating resist as the medium for pattern transfer, replaces the dry film to meet the pattern transfer requirements at the bottom of the stepped groove, and realizes the stepped pattern design of the printed circuit board.

[0038] Specifically, in one embodiment of the present invention, the step of opening a stepped groove after drilling holes in the pressed circuit board in S100 specifically includes: setting polypropylene between the circuit boards, and after setting tape in the area corresponding to the stepped groove, pressing the circuit boards.

[0039] Combined with the foregoing embodiments, in one embodiment of the present invention, the step of opening a stepped groove after drilling holes in the pressed circuit board in S100 further includes: when the process of electroplating on filled conductive vias is not required, all the copper deposition holes (referred to as PTH, Plating Through Hole in the industry) on the pressed circuit board are drilled at one time. And when the process of electroplating on filled conductive vias (referred to as POFV, Plating Over Filled Via in the industry) is required, then POFV is carried out first, and when drilling PTH through holes after POFV, all PTH holes are drilled.

[0040] Combined with the foregoing embodiments, in a specific implementation manner of the present invention, the steps of performing graphic electroplating to achieve graphic transfer in the non-step groove area include: achieving graphic transfer in the non-step groove area through film pressing, exposure, development, secondary electroplating, and tin-lead plating.

[0041] Combined with the foregoing embodiments, in another specific implementation manner of the present invention, in the steps after the detection program, the detection program includes: automatic optical inspection, forming electrical measurement, and appearance inspection.

[0042] Combined with the foregoing embodiments, in yet another specific implementation manner of the present invention, in the steps after the detection program, it further includes: after automatic optical inspection, applying ink to the bottom of the step groove.

[0043] In another embodiment of the present invention, the steps of removing the electroplating resist on the bottom of the step groove and performing circuit pattern etching on the step groove area and the non-step groove area successively include: removing the dry film, using laser ablation to remove the electroplating resist in the step groove area, using plasma to remove the residual electroplating resist, sandblasting to remove oxidation, and circuit pattern etching.

[0044] The following combines Figures 2 to 3 , and specific embodiments are given:

[0045] 1) Inner layer pattern making: According to the design requirements, operate the normal pattern.

[0046] 2) Lamination: Perform normal lamination, but the step groove process needs to be adopted on the step surface, and the step groove area is fished out on the outer layer by sticking tape. The tape uses the commonly used high-temperature tape in the industry.

[0047] 3) Drilling: If the circuit board product to be manufactured has no POFV, all PTHs are drilled at one time. If there is POFV, there are two drilling processes, that is, PTH is performed after POFV, and all PTH holes are drilled.

[0048] 4) Blind fishing: As Figure 2 shown, start controlling the depth blind fishing from layer L1 (in the industry, the milling process similar to machining is called fishing), and it is necessary to fish through layer L X layer, and do not fish to layer L X+1 layer. Through the step groove process, the blind fishing is formed to take out the high-temperature tape located between L X ~L X+1 to achieve the grooving process of the step groove.

[0049] 5) Resin removal: Laser the resin remaining in the step groove clean, and perform a de-smear process on the bottom of the step groove after laser to perform a primary degumming and cleaning process to ensure that the residual resin at the bottom is processed cleanly.

[0050] 6) Electroplating: Using the conventional PCB processing and production process, electroplating copper is carried out on all holes at one time, including the holes in the stepped groove area (belonging to the first copper electroplating).

[0051] 7) Coating process: Using electrostatic spraying, a layer of electroplating resist is sprayed on the bottom of the stepped groove as the medium for pattern transfer at the bottom of the stepped groove. Through the relevant process of spraying the electroplating resist, the pattern at the bottom of the stepped groove is formed (referred to as the negative film mode in the industry). The present invention uses an electroplating resist (characterized by acid and alkali resistance and laser removability) to replace the dry film processing technology, and through coating, such as electrostatic spraying, air spraying, etc. (not limited to the above processes), the requirement for pattern transfer at the bottom of the stepped groove is realized.

[0052] 8) Pattern electroplating process: For the non-stepped area, the pattern electroplating process (specifically through laminating, exposure, development, second copper electroplating, and tin-lead plating) is used to realize pattern transfer in the non-stepped area.

[0053] 9) Pattern etching process: After laser cleaning the electroplating resist in the stepped area, all patterns are etched out for both the stepped area and the non-stepped area together.

[0054] 10) AOI inspection: Optical inspection is carried out separately for the stepped area and the non-stepped area.

[0055] 11) Ink / Text: If the bottom of the step needs to be covered with ink, it is realized by the coating process. If there is text designed at the bottom of the step, it is realized by the inkjet text method after the ink application.

[0056] 12) Surface treatment: Normal operation.

[0057] 13) Forming electrical test: Normal operation.

[0058] 14) Appearance inspection: Normal operation.

[0059] Finally, a PCB product with a stepped pattern design is obtained.

[0060] Those skilled in the art of this technology can understand that the steps, measures, and solutions in various operations, methods, and processes discussed in this application can be alternated, changed, combined, or deleted. Further, the other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, changed, rearranged, decomposed, combined, or deleted. Further, those in the prior art that have steps, measures, and solutions in the various operations, methods, and processes disclosed in this application can also be alternated, changed, rearranged, decomposed, combined, or deleted.

[0061] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0062] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

[0063] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they may be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0064] The above are only some embodiments of this application. It should be noted that for those of ordinary skill in the art, without departing from the principle of this application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of this application.

Claims

1. A method for implementing a stepped printed circuit board, characterized in that, It includes the following steps: After drilling holes in the pressed circuit board, a stepped groove is opened, and electroplating operation is carried out; Electroplating resist is electrostatically sprayed on the bottom of the stepped groove to form a stepped groove area; For the non-stepped groove area outside the stepped groove area, pattern electroplating is carried out to achieve pattern transfer of the non-stepped groove area; The electroplating resist at the bottom of the stepped groove is removed, and circuit pattern etching is carried out on the stepped groove area and the non-stepped groove area; After passing the detection program, a stepped pattern printed circuit board is obtained.

2. The method for implementing a ladder-shaped printed circuit board according to claim 1, characterized in that, The step of opening a stepped groove after drilling holes in the pressed circuit board includes: Polypropylene is arranged between the circuit boards, and after a tape is arranged in the area corresponding to the stepped groove, the circuit boards are pressed together.

3. The method for implementing a ladder-shaped printed circuit board according to claim 1, wherein The step of opening a stepped groove after drilling holes in the pressed circuit board includes: When the process of electroplating on the filled conductive vias is not required, all the copper deposition holes on the pressed circuit board are drilled at one time.

4. The method for implementing a ladder-shaped printed circuit board according to claim 1, characterized in that The step of carrying out pattern electroplating to achieve pattern transfer of the non-stepped groove area includes: Through film pressing, exposure, development, secondary electroplating and tin-lead plating, pattern transfer of the non-stepped groove area is achieved.

5. The method for implementing a ladder-shaped printed circuit board according to claim 1, characterized in that, In the step after passing the detection program, the detection program includes: automatic optical detection, forming electrical measurement and appearance detection.

6. The method for implementing a ladder-shaped printed circuit board according to claim 5, wherein In the step after passing the detection program, it also includes: after the automatic optical detection, ink is coated on the bottom of the stepped groove.

7. The method for implementing a ladder-shaped printed circuit board according to claim 1, characterized in that, The steps of removing the electroplating resist at the bottom of the stepped groove and carrying out circuit pattern etching on the stepped groove area and the non-stepped groove area successively include: removing the dry film, using laser ablation to remove the electroplating resist in the stepped groove area, plasma removing the remaining electroplating resist, sandblasting to remove oxidation and circuit pattern etching.

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