A laser blind groove plate processing method

Abstract

The present invention discloses a method for processing a laser blind groove plate, comprising the following specific steps: step 1, transferring a pattern to a copper clad plate, and then etching the copper foil of the non-patterned part; step 2, applying a dry film to a core plate on which a circuit is formed, developing the core plate, and then opening a window at a position corresponding to the bottom area of ​​the blind groove in the inner layer; gold-plating the bottom area of ​​the blind groove with the window; step 3, completing lamination to form a multi-layer core plate; step 4, making an outer layer circuit, and at the same time, etching the metal layer corresponding to the blind groove area into a substrate; step 5, performing surface treatment on the outer layer pattern; step 6, laser ablating a substrate medium at the blind groove position to produce a blind groove, achieving the goal of retaining the gold-plated layer on the pattern circuit in the blind groove after laser ablation of the substrate medium, forming the blind groove while retaining the surface treatment of the pattern in the blind groove; compared with the existing blind groove production process, the surface treatment of the pattern in the blind groove and the outer layer pattern is achieved separately, and the surface treatment of the inner surface of the blind groove and the surface treatment of the outer layer can be inconsistent.

Description

Technical field

[0001] The invention relates to a blind groove processing technology on a circuit board, and in particular to a laser blind groove processing method for a circuit board. [Background Technology]

[0002] Blind vias in PCBs are holes that connect different layers of circuitry within a multilayer circuit board, but do not penetrate the entire board. Buried blind vias are holes that are soldered inside the holes to achieve internal circuit connections within the multilayer board. Blind vias play a vital role in increasing circuit density, reducing board size, and improving circuit performance.

[0003] When processing blind and buried vias on multi-layer PCBs, the following points should be considered: 1. Aperture accuracy. The aperture accuracy of blind vias directly affects the quality of the circuit connections on the multi-layer PCB. Therefore, the accuracy and consistency of the aperture must be ensured during the processing. 2. Surface treatment. The surface treatment of blind and buried vias is crucial to their conductivity and solderability. It is necessary to select an appropriate chemical treatment process and ensure the treatment quality. 3. Internal connections. The internal connection process of blind vias requires high technical requirements to ensure connection quality and stability. Therefore, the processing technology of blind and buried vias on multi-layer PCBs requires highly specialized equipment and process support, and also places very high demands on the accuracy and quality of the processing process.

[0004] like Figure 1 As shown, in the existing blind groove processing on the circuit board, the inner layer circuit is first produced, and then the two substrates are pressed together through the semi-cured sheet, and then the copper foil in the blind groove area is etched, and finally the substrate medium is ablated by laser to form the required blind groove. In the existing processing and production method, before pressing, it is sufficient to follow the conventional multi-layer circuit board processing and production, and after pressing, the blind groove is formed by laser ablation. This results in that after the blind groove is produced, the pattern inside the blind groove needs to be surface treated together with the outer layer pattern, because the surface inside the blind groove needs to be consistent with the outer layer surface. For example, gold plating, immersion gold, tin spraying and other processing processes are performed. Otherwise, subsequent processing cannot be carried out; resulting in the existing processing process being cumbersome and the processing efficiency being low. [Summary of the invention]

[0005] The present invention provides a laser blind groove plate processing method, which can realize that the inner pattern of the blind groove and the outer pattern are separately produced and surface treated, and the surface treatment of the inner surface of the blind groove and the surface treatment of the outer layer are not necessarily consistent; at the same time, when the inner pattern of the blind groove and the outer pattern are not conductive, the surface treatment of the inner pattern of the blind groove can also be performed.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for processing a laser blind groove board, according to the process of a multi-layer board core board, includes substrate production, film lamination, exposure after film lamination, development, etching and demoulding, and completing the inner layer circuit production, including the following specific steps:

[0008] Step 1: Transfer the pattern to the copper clad laminate by photochemical imaging, and then etch the copper foil of the non-patterned part;

[0009] Step 2: After applying dry film and developing on the core board with the circuit formed, a window is opened in the inner layer corresponding to the bottom area of ​​the blind groove;

[0010] The bottom area of ​​the blind slot with the window is plated with gold by electroplating to complete the surface treatment of the bottom of the blind slot;

[0011] Step 3: Complete the lamination to form a multi-layer core board;

[0012] Step 4: Make the outer layer circuit. While making the outer layer circuit, the metal layer corresponding to the blind groove area needs to be etched into the base material;

[0013] Step 5: Surface treatment of outer layer graphics;

[0014] Step 6: Laser ablate the substrate medium at the blind groove position to produce the blind groove. The laser needs to use infrared laser. By taking advantage of the low absorption rate of metal gold to infrared light, the gold-plated layer on the pattern circuit in the blind groove is retained after laser ablation of the substrate medium. The blind groove is formed while retaining the surface treatment of the pattern in the blind groove.

[0015] Furthermore, in the step 2, the size of the window area is at least 10 mil larger than the single side of the blind groove to avoid displacement after pressing and the edge of the blind groove not being surface treated.

[0016] The beneficial effects of the present invention are:

[0017] The present invention is based on the existing laser blind groove process. After the inner layer circuit is etched, the blind groove area is gold-plated before lamination. The size of the gold-plated area is at least 10 mil larger than the single side of the blind groove, so as to avoid deviation after lamination and the situation where the edge of the blind groove is not surface-treated. In addition, while laminating and etching the outer layer circuit, the copper foil in the blind groove area is etched. Then, the outer layer graphic circuit is surface-treated, so that the surface treatment can be inconsistent with that in the blind groove.

[0018] Furthermore, after lamination of the outer layer, an infrared laser, such as a CO2 laser, is used to laser ablate the substrate dielectric. This utilizes the low infrared light absorption rate of gold metal to achieve ablation of the substrate dielectric. This allows the gold-plated layer on the patterned circuit within the blind slot to be retained after laser ablation. This allows the blind slot to be formed while retaining the surface treatment of the pattern within the blind slot. By pre-gilding the inner layer and laser ablating the outer layer using a specific light source, different surface treatments can be achieved for the inner and outer layers of the blind slot. Furthermore, when there is no continuity between the pattern within the blind slot and the outer layer, the surface treatment of the pattern within the blind slot can also be performed.

Brief Description of the Drawings

[0019] Figure 1 This is a schematic diagram of the laser blind groove processing technology in the prior art;

[0020] Figure 2 This is a schematic diagram of the process of completing the inner layer circuit production of the multi-layer core board in the present invention;

[0021] Figure 3 This is a schematic diagram of the process of making the inner layer circuit in step 1 of the present invention;

[0022] Figure 4 This is a schematic diagram of the window opening process at the bottom area of ​​the blind groove in step 2 of the present invention;

[0023] Figure 5 This is an enlarged schematic diagram of the bottom area of ​​the blind groove after the window is opened in step 2 of the present invention;

[0024] Figure 6 This is a schematic diagram of the process of performing gold plating surface treatment on the bottom area of ​​the blind groove in step 2 of the present invention;

[0025] Figure 7 This is a schematic diagram of the lamination process in step three of the present invention;

[0026] Figure 8 This is a schematic diagram of the process of making the outer layer circuit and etching the metal layer in the blind groove area simultaneously in step 4 of the present invention;

[0027] Figure 9 This is a schematic diagram of the process of surface treatment of outer layer pattern production in step five of the present invention;

[0028] Figure 10 It is a schematic diagram of the process of laser ablation of the substrate medium at the blind groove position in step six of the present invention. [Specific implementation method]

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] A laser blind groove plate processing method, such as Figure 2 As shown, according to the multi-layer core board process, the substrate is made, the film is applied, and then the film is exposed, developed, etched and demoulded to complete the inner layer circuit production, which specifically includes the following steps:

[0031] Step 1: Figure 3 As shown, on the copper clad laminate, the pattern is transferred to the copper clad laminate by a photochemical imaging method, and then the copper foil of the non-patterned part is etched;

[0032] Step 2: Figure 4 As shown, on the core board where the circuit is formed, after applying dry film and developing, a window is opened in the inner layer corresponding to the bottom area of ​​the blind groove;

[0033] like Figure 5 As shown, the size of the window area is 10mil larger than the single side of the blind groove to avoid deviation after pressing and the edge of the blind groove not being surface treated; Figure 5 In the middle, the black part is the dry film covered area, and the dotted box is the blind groove area;

[0034] like Figure 6 As shown, the bottom area of ​​the blind groove with the window is plated with gold by electroplating, and then subjected to a stripping treatment to complete the surface treatment of the bottom of the blind groove;

[0035] Step 3: Figure 7 As shown, the lamination is completed to form a multi-layer core board;

[0036] Step 4: Figure 8 As shown, the outer layer circuit is made. At the same time as the outer layer circuit is made, the metal layer corresponding to the blind groove area needs to be etched into the substrate. The metal layer in the blind groove area is Figure 8 The position corresponding to the middle ellipse;

[0037] Step 5: Figure 9 As shown, the outer layer pattern is processed by surface treatment, such as gold plating, immersion gold, tin spraying, etc.

[0038] Step 6: Figure 10 As shown in the figure, the blind groove is produced by laser ablation of the substrate medium at the blind groove position. The laser needs to use an infrared laser, such as a CO2 laser machine. By taking advantage of the low absorption rate of metal gold to infrared light, the gold-plated layer on the pattern circuit in the blind groove is retained after laser ablation of the substrate medium. The blind groove is formed while retaining the surface treatment of the pattern in the blind groove.

[0039] In this embodiment, the inner layer is gold-plated on the patterned area within the blind trench. After the outer layer is laminated, laser ablation of the substrate dielectric is performed. A specific infrared laser, such as a CO2 laser, is used. This utilizes gold's low absorption rate for infrared light to achieve laser ablation of the substrate dielectric, preserving the gold-plated layer on the patterned circuitry within the blind trench. By pre-gold-plating the inner layer and laser ablation of the outer layer using a specific light source, different surface treatments can be achieved on the inner and outer layers of the blind trench. Furthermore, even when there is no continuity between the pattern within the blind trench and the pattern on the outer layer, surface treatment can still be performed on the pattern within the blind trench.

[0040] In the description of the present invention, it should be noted that the terms "inside" and "outside" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when in use. These 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. Therefore, they should not be understood as limitations on the present invention.

[0041] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Any equivalent changes made based on the shape, structure and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for processing a laser blind groove board, which follows the process of a multi-layer board core board, including substrate production, film lamination, exposure after film lamination, development, etching and demoulding, to complete the inner layer circuit production, characterized in that: The specific steps include: Step 1: Transfer the pattern to the copper clad laminate by photochemical imaging, and then etch the copper foil of the non-patterned part; Step 2: After applying dry film and developing on the core board with the circuit formed, a window is opened in the inner layer corresponding to the bottom area of ​​the blind groove; The bottom area of ​​the blind slot with the window is plated with gold by electroplating to complete the surface treatment of the bottom of the blind slot; Step 3: Complete the lamination to form a multi-layer core board; Step 4: Make the outer layer circuit. While making the outer layer circuit, the metal layer corresponding to the blind groove area needs to be etched into the base material; Step 5: Surface treatment of outer layer graphics; Step 6: Laser ablation of the substrate medium at the blind groove position to produce the blind groove. The laser should be infrared laser. Taking advantage of the low absorption rate of metal gold to infrared light, the gold-plated layer on the pattern circuit in the blind groove is retained after laser ablation of the substrate medium. The blind groove is formed while retaining the surface treatment of the pattern in the blind groove. In the step 2, the size of the window area is at least 10 mil larger than the single side of the blind groove to avoid deviation after pressing and the edge of the blind groove not being surface treated.

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