Processing method for etching high-density holes in PCB (Printed Circuit Board) panel

Abstract

The invention discloses a processing method for etching high-density holes in a PCB panel, and belongs to the technical field of PCB panel etching holes.The processing method for etching the high-density holes in the PCB panel comprises the steps that a film is manufactured according to the hole opening position of a PCB, and a dry film is attached to the surface of a substrate; transferring the hole position pattern on the film to a copper surface through an exposure and development process; removing the part, which is not completely removed due to development, of the pattern so as to ensure the integrity of the pattern; chemical etching is carried out, so that the copper surface at the position of the hole is etched, the substrate is exposed, and then the mask attached to the surface of the PCB is removed; and putting the substrate into plasma equipment, and simultaneously etching the exposed substrate at the trepanning position by using plasma. As the density of the blind holes is higher and higher and the size of the blind holes is smaller and smaller, the plasma hole carving shows the advantages because the total cost is not increased along with the increase of the density of the through holes, and the higher the density of the holes is, the lower the cost allocated to each hole in the plasma drilling process is.

Description

Technical Field

[0001] The invention relates to the technical field of PCB panel etching holes, and in particular to a processing method for etching high-density holes in a PCB panel. Background Art

[0002] As electronic devices develop towards smaller, thinner, more functional and lower cost, a key challenge is how to make high-density blind holes on panels to meet market demand. With the development of high-density PCBs, laser drilling technology has been widely used due to its non-contact processing, high precision and flexibility. Lasers can quickly and accurately form tiny blind or buried holes on PCBs, which is particularly suitable for the production of HDI boards. Laser drilling is divided into many types, such as carbon dioxide lasers and ultraviolet lasers. Among them, ultraviolet lasers are more suitable for fine processing due to their short wavelength and concentrated energy.

[0003] ABF is the most commonly used isolation layer between metal layers in PCB panel manufacturing. Generally speaking, laser drilling is currently a popular method for making blind holes on ABF layers. However, since laser drilling requires processing one by one, the cost of the laser drilling process will become very high as the blind hole density becomes higher and the blind hole size becomes smaller. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a processing method for etching high-density holes in a PCB panel, which can complete the drilling of all holes on the panel at the same time by plasma drilling, thereby reducing the drilling cost of high-density holes.

[0005] A method for etching high-density holes in a PCB panel according to an embodiment of the present invention includes:

[0006] Step 1: Make a film according to the opening position of the PCB and stick a dry film on the surface of the substrate;

[0007] Step 2: Transfer the hole pattern on the film to the copper surface through exposure and development process;

[0008] Step 3: Remove the part of the pattern that is not removed by development to ensure the integrity of the pattern;

[0009] Step 4: Perform chemical etching to etch the copper surface at the opening position to expose the substrate, and then remove the mask attached to the PCB surface;

[0010] Step 5: Place the substrate into the plasma equipment and use plasma to simultaneously etch the exposed substrate at the opening position.

[0011] The processing method for etching high-density holes in a PCB panel according to an embodiment of the present invention has at least the following beneficial effects: the plasma hole engraving process is based on the plasma etching process on the panel. Unlike the laser drilling process, the laser drilling process drills holes one by one on the substrate, while the plasma completes the engraving of all holes on the substrate at the same time. Therefore, as the density of blind holes increases and the size of blind holes decreases, the laser drilling process becomes very expensive, while plasma hole engraving shows its advantages because its total cost does not increase with the increase of through-hole density. The higher the hole density, the lower the cost allocated to each hole in the plasma drilling process. In addition, a further plasma decontamination process is required after the laser drilling process, but not after the plasma drilling process.

[0012] According to some embodiments of the present invention, in step 5, the plasma equipment has a high DC bias and a high plasma density, and a hole is opened on the substrate by vertical etching at a high etching rate.

[0013] According to some embodiments of the present invention, a plasma device includes a vacuum chamber, in which a ground electrode and a power electrode are disposed, a substrate is placed on the power electrode, and a plasma glow zone is formed between the power electrode and the ground electrode.

[0014] According to some embodiments of the present invention, in step 5, sufficient DC bias is added to the substrate via the powered electrode to perform vertical plasma etching.

[0015] According to some embodiments of the present invention, in step 5, microwave plasma is used as the plasma source.

[0016] According to some embodiments of the present invention, in step 5, radio frequency inductively coupled plasma is used as a plasma source.

[0017] According to some embodiments of the present invention, after step 5, the substrate is cleaned and copper plated.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0020] Figure 1 It is a flow chart of a method for processing high-density holes in a PCB panel according to an embodiment of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the plasma equipment in step 5 of the processing method for etching high-density holes in a PCB panel according to an embodiment of the present invention.

[0022] Reference numerals:

[0023] Plasma equipment 100 ; vacuum chamber 110 ; ground electrode 120 ; power electrode 130 ; plasma glow region 140 . DETAILED DESCRIPTION

[0024] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0025] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0026] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0028] refer to Figure 1 to Figure 2 A processing method for etching high-density holes in a PCB panel according to an embodiment of the present invention is described.

[0029] like Figure 1 to Figure 2 As shown, the processing method for etching high-density holes in a PCB panel according to an embodiment of the present invention includes:

[0030] Step 1: Make a film according to the opening position of the PCB and stick a dry film on the surface of the substrate;

[0031] Step 2: Transfer the hole pattern on the film to the copper surface through exposure and development process;

[0032] Step 3: Remove the part of the pattern that is not removed by development to ensure the integrity of the pattern;

[0033] Step 4: Perform chemical etching to etch the copper surface at the opening position to expose the substrate, and then remove the mask attached to the PCB surface;

[0034] Step 5: Place the substrate into the plasma equipment 100, and use plasma to etch the exposed substrate at the opening positions at the same time.

[0035] In step 5, the plasma device 100 has a high DC bias and a high plasma density, and a hole is opened on the substrate by vertical etching at a high etching rate. Microwave plasma or radio frequency inductively coupled plasma can be selected as the plasma source. After step 5, the substrate is cleaned and copper plated.

[0036] like Figure 2 As shown, the plasma device 100 includes a vacuum chamber 110, a ground electrode 120 and a power electrode 130 are arranged in the vacuum chamber 110, a substrate is placed on the power electrode 130, and a plasma glow zone 140 is formed between the power electrode 130 and the ground electrode 120. In step 5, sufficient DC bias is added to the substrate through the power electrode 130 to perform vertical plasma etching. The plasma device 100 used in step 5 has the ability to etch vertical blind holes, and the power electrode 130 provides a suitable DC bias for the substrate, which helps vertical etching. The high plasma density in the vacuum chamber 110 ensures a sufficient etching rate.

[0037] In the manufacture of PCB panels, plasma is used instead of laser drilling process to form blind holes on the isolation layer for interlayer connection. The isolation material can be ABF, BT, etc. Taking ABF as the isolation material as an example, oxygen-based plasma will be used to etch the organic material in ABF, and fluorine-based plasma will be used to remove the filler in ABF. The plasma device 100 has a high DC bias and a high plasma density to form a blind hole on the ABF layer.

[0038] There are two basic requirements for the plasma hole etching process: one is to form a high and uniform plasma in the plasma chamber to increase the etching rate, and the other is to add sufficient DC bias on the substrate for vertical plasma etching. Therefore, microwave plasma and RF inductively coupled plasma may be selected as the plasma source, and a second power supply may be used to add DC bias on the substrate, and both the plasma density and DC bias are independently controllable and adjustable.

[0039] The plasma drilling process is based on the plasma etching process on the panel. Unlike the laser drilling process, which drills holes one by one on the substrate, plasma completes the drilling of all holes on the substrate at the same time. Therefore, as the blind hole density becomes higher and the blind hole size becomes smaller, the laser drilling process becomes very expensive, and plasma drilling shows its advantages because its total cost does not increase with the increase of through-hole density. The higher the hole density, the lower the cost per hole in the plasma drilling process. As the number and density of holes increase, the speed of plasma drilling will also be faster than laser drilling. In addition, after the laser drilling process, a plasma process is required to remove the drilling stains in the holes, while no subsequent hole cleaning process is required after the plasma drilling process.

[0040] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A method for etching high-density holes in a PCB panel, characterized in that: include: Step 1: Make a film according to the opening position of the PCB and stick a dry film on the surface of the substrate; Step 2: Transfer the hole pattern on the film to the copper surface through exposure and development process; Step 3: Remove the part of the pattern that is not removed by development to ensure the integrity of the pattern; Step 4: Perform chemical etching to etch the copper surface at the opening position to expose the substrate, and then remove the mask attached to the PCB surface; Step 5: Place the substrate into the plasma equipment and use plasma to simultaneously etch the exposed substrate at the opening position.

2. The method for etching high-density holes in a PCB panel according to claim 1, characterized in that: In step 5, the plasma equipment has a high DC bias and a high plasma density, and a hole is opened in the substrate by vertical etching at a high etching rate.

3. The method for etching high-density holes in a PCB panel according to claim 2, characterized in that: The plasma equipment comprises a vacuum chamber, in which a grounding electrode and a power-connecting electrode are arranged, a substrate is placed on the power-connecting electrode, and a plasma glow zone is formed between the power-connecting electrode and the grounding electrode.

4. The method for etching high-density holes in a PCB panel according to claim 3, characterized in that: In step 5, sufficient DC bias is applied to the substrate via the powered electrode to perform vertical plasma etching.

5. The method for etching high-density holes in a PCB panel according to claim 4, characterized in that: In step 5, microwave plasma is used as a plasma source.

6. The method for etching high-density holes in a PCB panel according to claim 4, characterized in that: In step 5, radio frequency inductively coupled plasma is used as a plasma source.

7. The method for etching high-density holes in a PCB panel according to claim 1, characterized in that: After step 5, the substrate is cleaned and copper plated.

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