A production process for multi-layer PCB boards with refined circuits

Abstract

The present invention belongs to the production of circuit boards, and specifically discloses a production process of a refined circuit multilayer PCB board, including: step S1: processing a first via hole on a first single-sided copper-clad board; step S2: coating a conductive film on the first single-sided copper-clad board; step S3: processing a second via hole on the first single-sided copper-clad board; step S4: conductive treatment; step S5: copper plating treatment; S6: micro-etching treatment; step S7: stripping the conductive film; step S8: coating a conductive film on the second single-sided copper-clad board; step S9: processing a third via hole on the second single-sided copper-clad board; step S10: superimposing the second single-sided copper-clad board on the first single-sided copper-clad board, which keeps the third via hole aligned with the first via hole to form a connecting hole group; step S11: conductive treatment; step S12: copper plating treatment; step S13: micro-etching treatment; step S14: stripping the conductive film. The present invention can realize one-time electroplating forming of through holes, and the plating structure is good and the conductive performance is better.

Description

Technical Field

[0001] The present invention relates to the technical field of PCB board manufacturing, and in particular to a production process of a refined circuit multilayer PCB board. Background Art

[0002] With the rapid development of 5G technology, multi-layer circuit boards are developing towards refined circuits, with increasingly higher requirements for line width, spacing and other performance. In the process of making through-holes for refined circuits, since the through-holes of the previous layer of the board have been subjected to conductive and copper plating treatments, the through-holes that do not require electroplating will also form a partial electroplating layer, which will easily lead to delamination during the electroplating of the combined holes, causing the conductivity of the through-hole to decrease. Summary of the invention

[0003] The object of the present invention is to provide a production process for a multi-layer PCB board with refined circuits, which can realize one-time electroplating forming of through holes, has a good plating structure and better conductive performance.

[0004] The present invention is achieved through the following technical solutions:

[0005] A production process for a multi-layer PCB board with refined circuits comprises the following steps:

[0006] Step S1: machining a first via hole on a first single-sided copper clad laminate;

[0007] Step S2: coating a conductive film on the first single-sided copper-clad laminate;

[0008] Step S3: machining a second via hole on the first single-sided copper clad laminate;

[0009] Step S4: Conductive treatment, attaching a conductive material on the hole wall of the second conductive hole;

[0010] Step S5: copper plating treatment, so that the inner wall of the second via hole is electroplated into a copper hole;

[0011] Step S6: micro-etching to remove copper deposited on the conductive film;

[0012] Step S7: peeling off the conductive film;

[0013] Step S8: coating a conductive film on the second single-sided copper-clad laminate;

[0014] Step S9: machining a third via hole on the second single-sided copper clad laminate;

[0015] Step S10: stacking the second single-sided copper clad laminate onto the first single-sided copper clad laminate, keeping the third conductive hole aligned with the first conductive hole to form a connecting hole group;

[0016] Step S11: Conductive treatment, attaching a conductive material to the hole walls of the interconnected hole groups;

[0017] Step S12: copper plating treatment, so that the inner wall of the connecting hole group is electroplated into copper holes;

[0018] Step S13: micro-etching to remove copper deposited on the conductive film;

[0019] Step S14: peeling off the conductive film.

[0020] Optionally, before step S1, the process further includes drying the film, exposing, developing, etching and stripping each single-sided copper clad laminate.

[0021] Optionally, the Cu wire width of each single-sided copper clad laminate is: ≥75um;

[0022] Cu conductor spacing: ≥75um;

[0023] Cu wire thickness: ≤18um;

[0024] Thickness: 0.2mm.

[0025] Optionally, in step S10, before superimposing the second single-sided copper clad laminate onto the first single-sided copper clad laminate, a resin layer is first coated around the opening of the first conductive hole of the first single-sided copper clad laminate, and then the second single-sided copper clad laminate is superimposed onto the first single-sided copper clad laminate, and then placed in a freezing device for freezing treatment to solidify the resin, and then the resin layer is pierced through a drilling device, and then an exhaust device is arranged above the connecting hole group to suck out resin waste residue generated during drilling.

[0026] Optionally, the resin layer has a thickness of 0.1-0.2 mm.

[0027] The technical solution of the present invention has at least the following beneficial effects:

[0028] The present invention processes the individually formed through holes and the combined through holes separately before and after lamination, thereby ensuring that when the individually formed through holes are electroplated, no plating is formed on the combined through holes. In this way, after the combined holes are formed in the later stage, when one-time electroplating is realized, the integrity of the holes can be guaranteed, stratification can be avoided, and the conductive performance can be guaranteed to be intact. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the production process of a multi-layer PCB board with refined circuits of the present invention;

[0030] Icon: 100 - first single-sided copper clad laminate, 101 - first conductive hole, 110 - conductive film, 102 - second conductive hole, 200 - second single-sided copper clad laminate, 203 - third conductive hole, 210 - conductive film. DETAILED DESCRIPTION

[0031] Example 1

[0032] A production process for a multi-layer PCB board with refined circuits includes the following steps: pre-processing processes of pressing and drying the film, exposing, developing, etching and stripping each single-sided copper-clad board to realize the processing of the single-sided copper-clad board. The specific process parameters and process equipment can be realized by conventional technology in the field, and the embodiments will not be described in detail. After completing the pre-processing process, the following process steps are then implemented, referring to Figure 1 , including:

[0033] Step S1: machining a first via hole 101 on the first single-sided copper clad laminate 100. The via hole can be machined by mechanical drilling or laser machining.

[0034] Step S2: coating a layer of conductive film 110 on the first single-sided copper clad laminate 100 .

[0035] Step S3 : processing a second via hole 102 on the first single-sided copper clad laminate 100 . The processing method of the second via hole 102 is the same as that of the first via hole 101 .

[0036] Step S4: Conductive treatment, attaching a conductive material on the hole wall of the second conductive hole 102 .

[0037] Step S5: copper plating is performed to plate the inner wall of the second via hole 102 into a copper hole.

[0038] Step S6: micro-etching to remove copper deposited on the conductive film 110 .

[0039] Step S7: peeling off the conductive film 110 .

[0040] Step S8: coating a layer of conductive film 210 on the second single-sided copper clad laminate 200 .

[0041] Step S9: processing a third via hole 203 on the second single-sided copper clad laminate 200 .

[0042] Step S10: superimposing the second single-sided copper clad laminate 200 onto the first single-sided copper clad laminate 100, keeping the third via 203 aligned with the first via 101, to form a connecting hole group.

[0043] Step S11: Conductive treatment, attaching conductive material to the hole walls of the interconnected hole groups.

[0044] Step S12: copper plating treatment, so that the inner wall of the connecting hole group is electroplated into copper holes.

[0045] Step S13: micro-etching to remove copper deposited on the conductive film 210.

[0046] Step S14: peeling off the conductive film 210 .

[0047] The present invention makes a via hole on the first single-sided copper-clad board 100, that is, the board of the next layer, and selects different processing techniques according to different types of via holes. The first via hole 101 is pre-processed before being coated with a conductive film 110, so that it can be covered after coating, and the second via hole 102 is processed retroperitoneally. At this time, the second via hole 102 can be prevented from being covered by the conductive film 110 when the hole is plated, thereby affecting the electroplating effect. At the same time, the conductive film 110 covers the second via hole 102, and at the same time, it can be ensured that the first via hole 101 can remain unplated when the second via hole 102 is plated. If the first via hole 101 is partially electroplated, when the connecting hole group is subsequently made, it is easy to have a double-layer plating layer, and separation is easy to occur, resulting in a problem of decreased conductivity of the plated hole. Therefore, in the first processing, the first via hole 101 and the second via hole 102 are respectively realized by the pre-coating processing and retroperitoneal processing methods. After the first single-sided copper clad laminate 100 and the second single-sided copper clad laminate 200 are overlapped, the connecting hole group is electroplated to effectively ensure the integrity of the plating layer and the good conductivity.

[0048] Embodiment 2:

[0049] Due to the significant improvement in the accuracy of the exposure machine, the exposure effect will be degraded due to the diffraction spot phenomenon at the sharp part of the pattern, and some shadow areas that should not be exposed will also be irradiated by the light source, resulting in distortion at the chamfer of the pattern. In response to this type of distortion phenomenon, this embodiment, based on Example 1, considers the design and research of optical exposure compensation at the film design stage, and changes the diffraction area by correcting the exposure window design to improve the accuracy of pattern etching. The Cu wire line width of each single-sided copper clad laminate is: ≥75um; Cu wire spacing: ≥75um; Cu wire thickness: ≤18um; thickness: 0.2mm.

[0050] Embodiment 3:

[0051] On the basis of Example 1, in step S10, before the second single-sided copper clad laminate 200 is superimposed on the first single-sided copper clad laminate 100, a resin layer is first coated around the opening of the first conductive hole 101 of the first single-sided copper clad laminate 100, and then the second single-sided copper clad laminate 200 is superimposed on the first single-sided copper clad laminate 100, and then placed in a freezing device for freezing treatment to solidify the resin, and then the resin layer is pierced by a drilling device, and then an exhaust device is arranged above the connecting hole group to suck out the resin waste residue generated during drilling. In this embodiment, a resin layer is coated near the hole mouth, and the thickness of the resin layer is 0.1-0.2mm, and then another single-sided copper clad laminate is overlapped, so that a dense structure can be formed at the connecting part of the through hole of the two copper clad laminates. After the cold treatment, the resin can solidify quickly, and then the hole is repaired by drilling equipment in conjunction with exhaust equipment, and then electroplating treatment is performed to ensure the integrity of the hole. On the one hand, the resin can play an insulating role and has good insulation performance in the interlayer part, especially for PCB boards with fine circuits and narrow circuit spacing. If a copper hole defect occurs at the interlayer position after the hole is formed, it is easy to cause a short circuit at the position. On the other hand, after the resin is formed, it is ensured that the hole and the interlayer are relatively isolated, and the formed hole structure is more regular, which also helps to ensure the conductive performance of the copper hole.

Claims

1. A production process for a multi-layer PCB board with refined circuits, characterized in that: The following steps are involved: Step S1: machining a first via hole on a first single-sided copper clad laminate; Step S2: coating a layer of conductive film on the first single-sided copper-clad laminate, wherein the conductive film covers the first conductive hole; Step S3: machining a second via hole on the first single-sided copper clad laminate, wherein the second via hole penetrates the conductive film; Step S4: Conductive treatment, attaching a conductive material on the hole wall of the second conductive hole; Step S5: copper plating, so that the inner wall of the second conductive hole is electroplated into a copper hole, and the first conductive hole is not electroplated; Step S6: micro-etching to remove copper deposited on the conductive film; Step S7: peeling off the conductive film; Step S8: coating a conductive film on the second single-sided copper-clad laminate; Step S9: machining a third via hole on the second single-sided copper clad laminate; Step S10: stacking the second single-sided copper clad laminate onto the first single-sided copper clad laminate, keeping the third conductive hole aligned with the first conductive hole to form a connecting hole group; Step S11: Conductive treatment, attaching a conductive material to the hole walls of the interconnected hole groups; Step S12: copper plating treatment, so that the inner wall of the connecting hole group is electroplated into copper holes; Step S13: micro-etching to remove copper deposited on the conductive film; Step S14: peeling off the conductive film.

2. The production process of a multi-layer PCB board with refined circuits according to claim 1 is characterized in that: Before step S1, the process also includes drying the film, exposing, developing, etching and stripping each single-sided copper clad laminate.

3. The production process of a multi-layer PCB board with refined circuits according to claim 1 is characterized in that: The Cu wire width of each single-sided copper-clad laminate: ≥75um; Cu conductor spacing: ≥75um; Cu wire thickness: ≤18um; Thickness: 0.2mm.

4. The production process of a multi-layer PCB board with refined circuits according to claim 1 is characterized in that: In step S10, before the second single-sided copper clad laminate is stacked on the first single-sided copper clad laminate, a resin layer is first coated around the opening of the first conductive hole of the first single-sided copper clad laminate, and then the second single-sided copper clad laminate is stacked on the first single-sided copper clad laminate, and then placed in a freezing device for freezing treatment to solidify the resin, and then the resin layer is pierced by a drilling device, and then an exhaust device is set above the connecting hole group to suck out the resin waste residue generated during drilling.

5. The production process of a multi-layer PCB board with refined circuits according to claim 4 is characterized in that: The thickness of the resin layer is 0.1-0.2 mm.

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