A method for manufacturing a communication circuit board using RCC material

Abstract

The invention discloses a method for manufacturing a communication circuit board using an RCC material, comprising the following steps: laminating an RCC substrate and a prepared circuit board, subjecting the laminated plate to laminate structure control, positioning calibration and then drilling, adopting electric field sensing technology to control drilling depth during the drilling process, adjusting and optimizing drilling parameters to control hole wall roughness, sequentially cleaning, degumming, chemical copper deposition, and secondary copper plating of board and pattern after drilling, wherein the control accuracy of the drilling depth is ‑5 μm to 5 μm, and the hole wall roughness is ≤ 25 μm. The invention adopts mechanical drilling to drill microholes on each layer of the plate laminated with the RCC substrate on the circuit board, and meets the production needs of microholes on the circuit board by laminate structure control, electric field sensing to accurately control the drilling depth control method, and multi-point slicing detection to adjust and optimize the drilling parameters to control the hole wall roughness. Compared with laser drilling, the cost is lower, and the drilling quality is not affected by the thickness of the RCC substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of a method for manufacturing a communication circuit board, and in particular to a method for manufacturing a communication circuit board using an RCC material. Background Art

[0002] High-speed communication circuit boards are often equipped with high-density circuits. When manufacturing these circuit boards, high-density small holes are often opened in each layer. RCC materials, as dielectric materials, can be applied in thinner designs, which helps to replace the medicinal liquid in the electroplating of small holes, especially blind holes, and are therefore widely used.

[0003] At present, laser hole etching is widely used in circuit board drilling. In the process of opening blind holes, usually after RCC lamination and before laser hole etching, it is necessary to add a conformal window process for micro blind holes, that is, it is necessary to use traditional image transfer technology, by sticking photosensitive resist dry film or coating liquid photosensitive resist ink, through exposure, development, etching to form the alignment window of the surface micro blind hole, and then use CO2 laser for drilling. The process is complicated, and the laser is sensitive to the thickness of the RCC resin layer, resulting in a decrease in the qualified rate of micro holes below 100um, and there is a problem of alignment accuracy of micro blind holes. Moreover, although laser hole etching is fast, the drilling is done by drilling single layers of each layer and then overlapping instead of stacking and drilling, so the drilling cost is much higher than mechanical drilling.

[0004] However, the traditional mechanical drilling process is difficult to meet the requirements of micro-hole production. Drilling blind holes requires the tool to have very high precision in the 2-axis direction to ensure that the epoxy layer is just drilled through without damaging the next layer of copper foil. However, due to factors such as the flatness of the drilling machine table and the warping of the printed circuit board, it is impossible to strictly guarantee that the mechanical drilling of blind holes is accurate to the millimeter. The drilling depth can only be controlled at ±50μm, which is far from meeting the needs of blind hole production. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for manufacturing a communication circuit board using RCC material, which can well control the drilling depth and drilling flatness and has low cost.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A method for manufacturing a communication circuit board using RCC material comprises the following steps:

[0008] S1 laminates the RCC substrate and the prepared circuit board;

[0009] After S2 lamination, the laminated plate is controlled on the drilling machine, and then the drilling position is positioned and calibrated, and the drill bit is selected according to the hole diameter requirements. The drilling process uses electric field sensing technology to control the drilling depth, and 9-point sampling and slicing detection are used to adjust and optimize the drilling parameters to control the hole wall roughness;

[0010] S3 The plate after drilling is cleaned, de-glued and electrolessly coppered in turn;

[0011] S4 The plate after chemical copper deposition is subjected to electroplating, and then sliced ​​again to check the roughness of the hole wall;

[0012] S5: The board after electroplating is subjected to secondary copper plating to form conductive patterns and circuits on the board;

[0013] S6 For each additional layer, S1 to S5 need to be repeated until the required number of layers is reached, and then the layers are stacked in a predetermined order;

[0014] The control accuracy of the above drilling depth is -5μm to 5μm, and the hole wall roughness is ≤25um.

[0015] In order to further control the drilling quality, the above scheme can be further improved as follows:

[0016] In step S2, the method for controlling the laminated structure is to place the laminated sheet on a base plate, and to reinforce the laminated sheet with wrinkle glue on four sides of the base plate.

[0017] The bottom plate is a cardboard with an aspect ratio of 7:1.

[0018] In the step S2, the drilling position is covered with an aluminum sheet and a phenolic backing plate in sequence, and the thickness of the aluminum sheet is 0.3 mm.

[0019] In the step S2, an electric field sensor is integrated on the drill bit.

[0020] The drill bit is a fine steel drill bit of a 90° diameter, the drill tip of the drill bit is double-opened at a 90° angle, and the drill bit is ground or replaced after drilling 150-200 hits.

[0021] In step S3, the degumming rate is 0.2-0.25 g / cm 2 .

[0022] In the step S3, the backlight level after chemical copper deposition is greater than level 9.5.

[0023] In the step S4, the current density of the plate electrification is 16asf, the plate electrification time is 17min, and the copper thickness of the hole wall after the plate electrification is 3-6um.

[0024] In the step S5, the current density of the secondary copper plating is 18asf, the copper plating time is 75min, and the copper thickness of the hole wall after the secondary copper plating is 21-25um.

[0025] In the manufacturing method of a communication circuit board using RCC materials of the present invention, mechanical drilling is used in the drilling process to drill microholes on each layer of the circuit board laminated with the RCC substrate. The stacked structure is controlled, the drilling depth is accurately controlled by electric field sensing, and the hole wall roughness is controlled by adjusting and optimizing the drilling parameters through multi-point slicing detection. This meets the production needs of microholes on the circuit board, avoids drilling deviations that lead to poor conduction or even short circuits in high-density wiring on high-speed communication circuit boards, and affects the speed and integrity of signal transmission. Compared with laser drilling, the cost is lower and the drilling quality is not affected by the thickness of the RCC substrate. DETAILED DESCRIPTION

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] In order to solve the problem that laser drilling is sensitive to RCC thickness during circuit board manufacturing, it is difficult to ensure the qualified rate of micropores with RCC thickness below 100 μm, and the cost is high, the present invention provides a method for manufacturing a communication circuit board using RCC material, comprising the following steps:

[0030] S1 laminates the RCC substrate after copper thinning with the prepared circuit board;

[0031] After S2 lamination, the laminated plate is controlled on the drilling machine, and then the drilling position is positioned and calibrated, and the drill bit is selected according to the hole diameter requirements. The drilling process uses electric field sensing technology to control the drilling depth, and 9-point sampling and slicing detection are used to adjust and confirm the drilling parameters to control the hole wall roughness;

[0032] S3 The plate after drilling is cleaned, de-glued and electrolessly coppered in turn;

[0033] S4 The plate after chemical copper deposition is subjected to electroplating, and then sliced ​​again to check the roughness of the hole wall;

[0034] S5: The board after electroplating is subjected to secondary copper plating to form conductive patterns and circuits on the board;

[0035] S6 For each additional layer, S1 to S5 need to be repeated until the required number of layers is reached, and then the layers are stacked in a predetermined order;

[0036] The control accuracy of the above drilling depth is -5μm to 5μm, and the hole wall roughness is ≤25um.

[0037] In the manufacturing method of the present invention, mechanical drilling is used in the drilling process to drill microholes on each layer of the circuit board laminated with the RCC substrate, and the stacked structure is controlled, the drilling depth is accurately controlled by electric field sensing, and the drilling parameters are adjusted and optimized by multi-point slicing detection to control the hole wall roughness. The production needs of the microholes on the circuit board are met, and drilling deviations are avoided to prevent poor conduction or even short circuit of high-density wiring on high-speed communication circuit boards, thereby affecting the speed and integrity of signal transmission.

[0038] In an embodiment of manufacturing a high thermal conductivity and high precision communication circuit board with a board thickness of 1.5 mm and an RCC thickness of 0.2 mm, an RCC substrate is laminated with the prepared circuit board. The RCC substrate is composed of copper foil with a roughened, heat-resistant and anti-oxidation treated surface and a B-stage resin.

[0039] The laminated sheet is placed on the drilling machine platform to fix the laminated structure. Specifically, the laminated sheet is placed on the bottom plate, and the four sides of the bottom plate are reinforced with corrugated glue. The bottom plate serves as the bottom support of the sheet to improve the flatness of the sheet, and together with the corrugated glue, it reinforces the laminated structure of the sheet to prevent displacement or deformation during the drilling process. The bottom plate uses cardboard with an aspect ratio of 7:1. Choosing a suitable aspect ratio helps ensure the uniformity and quality of the drilling, and reduces drilling difficulties or quality problems caused by an excessively large ratio of sheet thickness to hole diameter.

[0040] The plate material reinforced with the laminated structure is covered with aluminum sheet and phenolic pad in sequence at the drilling position. The thickness of the aluminum sheet is 0.3mm. The aluminum sheet has good thermal conductivity and hardness, and can absorb the heat generated during the drilling process to prevent the drill bit from overheating, deformation or damage. Compared with the existing process of using 0.2mm aluminum sheet plus cardboard pad, the aluminum sheet is thickened to 0.3mm to further provide sufficient support force and reduce vibration and shaking during the drilling process. The cardboard is replaced with a phenolic pad. The phenolic pad has high hardness, high temperature resistance, and deformation resistance, which protects the material below the drilling position from damage and improves the accuracy and efficiency of drilling.

[0041] In order to avoid the problem that the traditional mechanical drilling process is difficult to ensure that the epoxy layer is drilled through without damaging the next layer of copper foil, and the drilling depth can only be controlled within ±50μm, it is necessary to control the drilling depth more accurately. In step S2, an electric field sensor is integrated on the drill bit, and the drill bit can stop drilling when it contacts the specified signal on the metal surface. In this way, the control depth can reach ±5μm, which can meet the requirements for manufacturing blind holes.

[0042] The drill bit is made of fine steel with a diameter of 1.5 mm. The drill tip is staggered at 90°. This design helps to better disperse the cutting force during the drilling process, improve cutting efficiency and precision. At the same time, the staggered double-opening structure also helps to reduce the wear and stagnation of the drill bit and extend the service life of the drill bit. In order to avoid the problem of inaccurate drilling caused by the wear of the drill bit during use, the drill bit needs to be ground or replaced after drilling 150-200 hits.

[0043] In order to further reduce the vibration and friction during the drilling process, thereby reducing the roughness of the hole wall, 9-point sampling and slicing detection is used to adjust and optimize the drilling parameters such as the drill speed and feed speed to control the roughness of the hole wall. In this embodiment, the drilling parameters of the 0.25mm drill bit are first used as the basis for the drilling parameters of the 0.2mm drill bit, the drilling speed is increased by 1 / 3, the lowering speed is reduced by 1 / 3, and the starting speed is reduced by 1 / 3. After drilling, sampling and slicing are performed in a 9-point manner, and the drilling-related parameters are fine-tuned according to the roughness of the 9-point slicing hole to ensure that the roughness of the hole wall is controlled to ≤25um.

[0044] The hole roughness is controlled within the range of ≤25um, and section inspection is arranged after drilling and board electroplating.

[0045] After drilling, epoxy drill dirt will remain in the hole, which is not conducive to the deposition of chemical copper and may cause the coating in the hole to peel off and fall off. Therefore, cleaning and degumming are performed before chemical copper deposition. In this embodiment, the cleaning and degumming in step S3 include the following steps: using an air gun to blow the hole, ultrasonic and high-pressure water washing 100% fully open, and then brushing the plate to remove the glue. After brushing, check the hole drilled by the 0.2mm drill bit with light to check whether there is copper powder plugging the hole. In order to ensure better and more uniform deposition of copper on the hole wall in the future, the degumming rate is controlled at 0.2-0.25g / cm 2 .

[0046] After the glue is removed, the board is electrolessly plated with copper to deposit a thin layer of copper on the entire printed board (especially the hole wall) so that the hole can be electroplated later to metalize the hole and achieve interlayer conduction. After electroless copper deposition, the quality of the copper deposition is evaluated through backlight detection to ensure that the backlight level after copper deposition is greater than 9.5, which meets the quality design requirements of the copper deposition layer and avoids affecting the electrical function and reliability of the PCB.

[0047] The copper layer of the plate after chemical copper plating may not be completely stable. By curing in a water tank, the copper layer can be further stabilized and solidified, and the board surface can be adjusted to improve its mechanical properties, corrosion resistance and flatness. In this embodiment, the board is electroplated within 6 hours of curing in a water tank after chemical copper plating.

[0048] The copper layer must be thickened by electroplating in a water tank for no more than 6 hours to improve the thickness and uniformity of the copper layer. In this embodiment, the current density of the electroplating is controlled at 16asf in step S4, the electroplating time is 17min, and the copper thickness of the hole wall is controlled at 3-6um after electroplating. The roughness of the hole wall is sliced ​​again after electroplating to ensure a good combination between the metallization layer and the hole wall, thereby improving the reliability and durability of the circuit board.

[0049] After the plate is cleaned and pretreated, it is subjected to secondary copper plating, which can increase the copper thickness of the outer layer of the plate to enhance the conductivity and meet the subsequent process requirements. In step S5 of this embodiment, the current density of the secondary copper plating is 18asf, the copper plating time is 75min, and the copper thickness after the secondary copper plating is controlled to be 21-25um. In order to protect the integrity of the circuit and the hole during etching, a layer of tin can be plated on the copper plating layer.

[0050] In a multi-layer design, the above steps are repeated for each additional layer until the desired number of layers is reached, and the layers are then stacked in a predetermined order.

[0051] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for manufacturing a communication circuit board using RCC material, characterized in that: The steps include: S1 laminates the RCC substrate and the prepared circuit board; After S2 lamination, the laminated plate is controlled on the drilling machine, and then the drilling position is positioned and calibrated, and the drill bit is selected according to the hole diameter requirements. The drilling process uses electric field sensing technology to control the drilling depth, and 9-point sampling and slicing detection are used to adjust and optimize the drilling parameters to control the hole wall roughness; S3 The plate after drilling is cleaned, de-glued and electrolessly coppered in turn; S4 The plate after chemical copper deposition is subjected to electroplating, and then sliced ​​again to check the roughness of the hole wall; S5: The board after electroplating is subjected to secondary copper plating to form conductive patterns and circuits on the board; S6 For each additional layer, S1 to S5 need to be repeated until the required number of layers is reached, and then the layers are stacked in a predetermined order; The control accuracy of the above drilling depth is -5μm to 5μm, and the hole wall roughness is ≤25um.

2. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In step S2, the method for controlling the laminated structure is to place the laminated sheet on a base plate, and to reinforce the laminated sheet with wrinkle glue on four sides of the base plate.

3. The method for manufacturing a communication circuit board using RCC material according to claim 2, characterized in that: The bottom plate is a cardboard with an aspect ratio of 7:

1.

4. The method for manufacturing a communication circuit board using RCC material according to claim 2, characterized in that: In the step S2, the drilling position is covered with an aluminum sheet and a phenolic backing plate in sequence, and the thickness of the aluminum sheet is 0.3 mm.

5. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In the step S2, an electric field sensor is integrated on the drill bit.

6. The method for manufacturing a communication circuit board using RCC material according to claim 5, characterized in that: The drill bit is a fine steel drill bit of a 90° diameter, the drill tip of the drill bit is double-opened at a 90° angle, and the drill bit is ground or replaced after drilling 150-200 hits.

7. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In step S3, the degumming rate is 0.2-0.25 g / cm 2 .

8. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In the step S3, the backlight level after chemical copper deposition is greater than level 9.

5.

9. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In the step S4, the current density of the plate electrification is 16asf, the plate electrification time is 17min, and the copper thickness of the hole wall after the plate electrification is 3-6um.

10. The method for manufacturing a communication circuit board using RCC material according to claim 1, characterized in that: In the step S5, the current density of the secondary copper plating is 18asf, the copper plating time is 75min, and the copper thickness of the hole wall after the secondary copper plating is 21-25um.