A method for embedding a device on a circuit board based on laser slotting

Abstract

The application discloses a method for embedding devices based on laser slotting on a circuit board, comprising the following steps: S1. cutting: cutting prepreg into a base body according to a preset size; S2. laser slotting: processing a through slot on the base body on a laser cutting platform to obtain a sample, wherein, during the processing, first cutting is performed on the upper surface of the base body to form a first slot with a V-shaped longitudinal section and an opening width of D1; second cutting is performed in the first slot to pass through the lower surface of the base body to obtain a second slot with a vertical side wall and a width of D2, wherein D2 is less than D1, and the first slot and the second slot are communicated to form the through slot; S3. cleaning the slot hole; S4. pressing and bonding glue on the lower surface of the sample; S5. mounting devices in the through slot; S6. pressing and bonding base material above the sample after mounting the devices; S7. removing the bonding glue and pressing and bonding base material on the side surface, and then, appearance detection is performed to obtain a sample with completed device embedding. When the devices are embedded, the devices are not prone to interference with the slot side wall to cause the devices to be warped, and the product qualified rate is high.

Description

Technical Field

[0001] This invention belongs to the field of embedded device technology on circuit boards, and specifically relates to a method for embedding devices on circuit boards based on laser grooving. Background Technology

[0002] Currently, capacitors are commonly used in electronic devices to store charge and provide power stability. Traditionally, capacitors are mounted by connecting them to the circuit board with leads, but this method takes up considerable space and is susceptible to external interference. Embedded capacitor technology, by embedding the capacitor inside the circuit board, can significantly reduce the board's size and improve capacitor stability. However, implementing embedded capacitor technology requires several special process steps. First, a hole matching the capacitor's size needs to be created on the surface of the circuit board. Then, the capacitor's leads are inserted into the hole and secured using appropriate soldering techniques. Finally, a cover layer is used to encapsulate the capacitor to the circuit board surface to ensure its safety and stability.

[0003] The slots used to embed capacitor components can generally be machined using a mechanical milling machine or a laser cutting machine. Mechanical milling machines are limited by the minimum cutter size and cannot machine slots less than 1mm wide. When conventional laser cutting equipment processes through slots in materials thicker than 1mm, as the cutting depth increases, the laser energy decreases due to two main issues: firstly, the machined plane is not in the focal position, causing laser energy attenuation; secondly, the already machined area blocks some of the laser beam, leading to further energy attenuation at deeper levels of the slot. This results in a large taper on the sidewalls after cutting the slot, which can easily cause misalignment during subsequent component embedding, affecting the overall product yield.

[0004] Therefore, a new technology is needed to solve the problem that interference easily occurs when embedded devices come into contact with the sidewall of the groove in the existing technology, which affects the product qualification rate. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a method for embedding devices on a circuit board based on laser grooving. When the size of the embedded device is close to the actual grooving size, interference is less likely to occur when the device contacts the sidewall of the grooving during embedding, thus preventing the device from lifting and resulting in a high product qualification rate.

[0006] The present invention adopts the following technical solution:

[0007] A method for embedding components on a circuit board based on laser grooving includes the following steps:

[0008] S1. Cutting: Cutting the prepreg into prepreg substrates of preset dimensions;

[0009] S2. Laser grooving: The substrate formed after cutting is fixed on a laser cutting platform, and a through groove is processed through the upper and lower surfaces of the substrate. After the through groove is processed, a sample is obtained.

[0010] S21. According to the maximum groove width D1 required by the established document, a first cut is made in a designated area on the upper surface of the substrate, and a first groove with tapered sidewalls is obtained after the cut. The longitudinal section of the first groove is V-shaped.

[0011] S22. According to the groove width D2 required by the predetermined document, a second cut is made downward in the first cutting groove area and penetrates the lower surface of the substrate. After cutting, a second cutting groove is vertically set on the side wall. The remaining part of the first cutting groove is connected with the second cutting groove to form the through groove, wherein D2 is less than D1.

[0012] S3. Clean the slots on the sample;

[0013] S4. Adhesive pressing: The lower surface of the sample is first overlapped with the adhesive and pre-pressed, and then fast pressing is performed according to the predetermined conditions;

[0014] S5. Component mounting: According to the design drawings, mount the corresponding components in the designated through slots respectively;

[0015] S6. Substrate lamination: The upper surface of the sample with the device mounted in step S5 is first overlapped and pre-pressed with the single-sided substrate, and then laminated according to the predetermined conditions. After lamination, the insulating medium in the single-sided substrate can fill the gaps around the device.

[0016] S7. Adhesive removal: Remove the adhesive from the lower surface of the sample after the substrates are pressed together in step S6;

[0017] S8. Substrate lamination: The surface after the adhesive has been removed in step S7 is first overlapped and pre-pressed with the single-sided substrate, and then laminated according to the predetermined conditions;

[0018] S9. Appearance inspection: Perform appearance inspection. Once the appearance inspection is qualified, a sample with one layer of device embedding can be obtained.

[0019] As a further improvement to the technical solution of the present invention, the prepreg is made of an insulating material.

[0020] As a further improvement to the technical solution of the present invention, in step S2, the semi-cured sheet is fixed on the laser cutting platform by adsorption.

[0021] As a further improvement to the technical solution of the present invention, in step S21, the laser cutting power of the first cut is 5w-6w, the laser scanning speed is 200mm / s-300mm / s, the laser cutting frequency is 45KHZ-55KHZ, the number of laser cuts is 1-4, and the Z-axis height is set to 0mm.

[0022] As a further improvement to the technical solution of the present invention, in step S22, the laser cutting power of the second cut is 3w-3.6w, the laser scanning speed is 250mm / s-350mm / s, the laser cutting frequency is 45KHZ-55KHZ, the number of laser cuts is 3-6, and the Z-axis height is set to -0.001mm.

[0023] As a further improvement to the technical solution of the present invention, the difference between D1 and D2 is not less than 10μm.

[0024] As a further improvement to the technical solution of the present invention, in step S2, the four sidewalls of the first groove are connected end to end in a conical shape; the connection node between two adjacent sidewalls of the second groove is an arc transition surface.

[0025] As a further improvement to the technical solution of the present invention, in step S2, the laser processing path of the first cut and the laser processing path of the second cut both include a first path and a second path. The first path is rectangular, and the second path is line segment-shaped. The two ends of the second path are respectively connected to the opposite sides of the rectangle of the first path.

[0026] As a further improvement to the technical solution of the present invention, in step S2, the lengths of the first groove and the second groove are equal.

[0027] As a further improvement to the technical solution of the present invention, in step S3, a plasma device is used to clean the groove.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] When the size of the embedded component is close to the actual groove size, the laser-grooved embedded component method used in this solution places the component within the through groove, with its lower part located within the second groove. This prevents the component from contacting the inclined sidewall of the first groove and lifting it, thus improving the product yield. Furthermore, the inclined sidewall of the first groove facilitates a smoother embedding process, reduces the taper of the sidewall after laser cutting, and replaces post-embedding soldering with adhesive bonding, resolving the issue of misalignment that easily occurs when embedding small components such as capacitors using deep laser-cut grooves. Attached Figure Description

[0030] The technology of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] Figure 1 This is a process flow diagram of laser-grooved embedded devices on a circuit board according to the present invention;

[0032] Figure 2 It shows a cross-sectional view of the grooving area and the laser processing paths for the first and second cuts.

[0033] Figure label:

[0034] 1-Base; 11-Through groove; 12-Grooving area;

[0035] 2-Adhesive;

[0036] 3-Single-sided substrate;

[0037] 4- Devices;

[0038] 5- Laser processing path for the first cut; 51- First path; 52- Second path;

[0039] 6- The laser processing path for the second cut;

[0040] 7-Copper layer. Detailed Implementation

[0041] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The same reference numerals used throughout the accompanying drawings indicate the same or similar parts.

[0042] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "up," "down," "left," and "right" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0043] Reference Figure 1 A method for embedding devices on a circuit board based on laser grooving includes the following steps:

[0044] S1. Cutting: Cutting the prepreg into prepreg substrate 1 of a preset size. The prepreg is made of insulating material, preferably ABF or PP or other insulating media.

[0045] S2. Laser grooving: The substrate 1, formed after cutting, is fixed on a laser cutting platform, and a through groove 11 is machined through the upper and lower surfaces of the substrate 1. After the through groove 11 is machined, a sample is obtained. The semi-cured sheet is fixed to the laser cutting platform by adsorption. The number of through grooves on the substrate can be set according to the number of devices to be embedded, and the size of each through groove can be determined according to the size of the device to be embedded.

[0046] S21. According to the maximum groove width D1 required by the predetermined document, a first cut is made in the designated grooving area 12 on the upper surface of the substrate 1. After cutting, a first groove with tapered sidewalls is obtained. The longitudinal section of the first groove is V-shaped, and the four sidewalls of the first groove are connected end to end in a tapered shape. The length of the first groove is L. The laser processing path 5 of the first cut includes a first path 51 and a second path 52. The first path 51 is rectangular, and the second path 52 is line segment-shaped. The two ends of the second path 52 are respectively connected to the opposite sides of the rectangle of the first path 51. The corresponding laser grooving parameters can be determined according to the actual thickness of the substrate 1 in the grooving area. The laser cutting power of the first cut is 5W-6W, the laser scanning speed is 200mm / s-300mm / s, the laser cutting frequency is 45KHZ-55KHZ, the number of laser cuts is 1-4, and the Z-axis height is set to 0mm.

[0047] S22. According to the groove width D2 required by the predetermined document, a second cut is made downward within the area of ​​the first cut groove, penetrating the lower surface of the substrate 1. After cutting, a second cut groove with vertically arranged sidewalls is obtained. The connection node between two adjacent sidewalls of the second cut groove is an arc transition surface. The remaining part of the first cut groove communicates with the second cut groove to form the through groove 11, wherein D2 is less than D1, the difference between D1 and D2 is not less than 10μm, and the difference between D1 and D2 can be selected as 10μm. The laser cutting power of the second cut is 3w-3.6w, the laser scanning speed is 250mm / s-350mm / s, the laser cutting frequency is 45KHZ-55KHZ, the number of laser cuts is 3-6, and the Z-axis height is set to -0.001mm. In the first grooving process, the Z-axis height is set to 0mm. At this time, the laser is in a positive focus state on the processing surface. In the second grooving process, the Z-axis height is set to -0.001mm. This setting allows time for the laser cutting equipment to adjust the Z-axis focus after the first processing. During the two processing cycles, it avoids the continuous accumulation of heat at the same processing position, effectively reducing the thermal impact. The actual laser grooving parameters can be adjusted according to the thickness of the grooving medium. The lengths of the first and second grooves are equal. The laser processing path 6 for the second cut is similar to the laser processing path 5 for the first cut in the horizontal direction. Both the laser processing path 6 for the second cut and the laser processing path 5 for the first cut are composed of a rectangle plus line segments. The purpose of adding line segments is to break up the cutting waste during processing, facilitating waste removal after cutting.

[0048] As product packaging requirements become increasingly smaller, the precision and requirements for product processing also become more stringent. Therefore, the external dimensions of the embedded device 4 are becoming increasingly similar to the dimensions of the groove. When embedding device 4, the four corners of a conventionally cut groove are either right angles or sharp angles. Therefore, after using a conventional groove, the groove appears as an inverted trapezoid. During actual embedding of device 4, if there is a slight misalignment of device 4 within the groove, one corner of device 4 will contact and interfere with another corner of the groove, causing it to lift up and preventing further embedding. In this solution, the two right angles within the second groove are rounded. After the groove is cut, the four corners form a semi-cylinder extending outwards, creating a rounded transition surface. This solves the problem that when the external dimensions of the embedded device 4 are close to the actual groove dimensions, if device 4 is slightly misaligned during embedding, one corner of device 4 will extend into the semi-cylinder position at one corner of the groove, preventing interference with the sidewall of the through groove 11.

[0049] When the external dimensions of the embedded device 4 are close to the actual dimensions of the second groove, during the embedding of device 4, the lower part of device 4 is located within the second groove, and device 4 will not come into contact with the inclined sidewall of the first groove and thus not lift up, improving the product yield. Furthermore, the inclined design of the sidewall of the first groove makes the embedding process of device 4 smoother. Also, only the upper sidewall of the through groove 11 is inclined, and the sidewall of the first groove does not need to connect with the bottom surface of the substrate 1, reducing the taper of the sidewall of the first groove after laser cutting.

[0050] S3. Clean each slot on the sample using a plasma device.

[0051] S4. Adhesive 2 Pressing: The lower surface of the sample is first overlapped and pre-pressed with adhesive 2, and then fast-pressed according to predetermined conditions. The process of fixing device 4 with adhesive 2 replaces the welding fixing process after device 4 is embedded, and solves the problem of easy misalignment of small-sized device 4 based on laser-cut deep groove embedding.

[0052] S5. Mounting Components 4: According to the design drawings, mount the corresponding components 4 in the designated through slots 11, such as mounting capacitors in the through slots 11.

[0053] S6. Substrate lamination: The sample or substrate 1 with the device 4 already mounted in step S5 is first overlapped and pre-pressed with the single-sided substrate 3, and then laminated according to predetermined conditions. After lamination, the insulating medium in the single-sided substrate 3 can fill the gaps around the device 4, thus fixing the device 4. A copper layer 7 can be provided on the upper surface of this single-sided substrate 3. The specific material used to make the single-sided substrate 3 can be a material with filling properties during lamination.

[0054] S7. Adhesive 2 removal: Remove the adhesive 2 from the lower surface of the sample after the substrate is pressed together in step S6.

[0055] S8. Substrate lamination: The surface after removing the adhesive 2 in step S7 is first laminated and pre-pressed with the single-sided substrate 3, and then laminated according to predetermined conditions to obtain a sample with a completed device 4 embedded. A copper layer 7 can be provided on the lower surface of this single-sided substrate 3.

[0056] S9. Appearance inspection: Perform appearance inspection. If the appearance inspection is qualified, a qualified sample with one layer of device 4 embedded can be obtained.

[0057] In one embodiment, the method of embedding devices on a circuit board using laser grooving, based on the actual thickness of the substrate 1 in the grooving area, determines the specific values ​​of the corresponding laser grooving parameters. The determined laser grooving parameters are input into the laser cutting machine, and the cutting process file is created. The cutting process file includes a first grooving processing drawing and a second grooving processing drawing. The laser processing path 5 for the first cut is recorded on the first grooving processing drawing, and the laser processing path 6 for the second cut is recorded on the second grooving processing drawing. After the laser cutting equipment automatically grasps the positioning points on the substrate to accurately locate the processing area, it performs the first cut according to the first grooving processing drawing as required by the predetermined document. After the first cut, the laser cutting equipment performs the second cut according to the second grooving processing drawing as required by the predetermined document. In this embodiment, the kerf length of the first laser processing path 5 is B, and the kerf width is A1. The kerf length of the second laser processing path 6 is B, and the kerf width is A2 = A1 - 60μm. The groove width recorded on the second grooving processing drawing is formed by reducing the overall groove width recorded on the first grooving processing drawing by 60μm. Refer to the attached drawing. Figure 2 As shown. In the first grooving process, the Z-axis height is set to 0mm, at which point the laser is in a focused state on the processing surface. In the second grooving process, the Z-axis height is set to -0.001mm. This setting allows time for the laser cutting equipment to adjust the Z-axis focus after the first processing, preventing continuous heat accumulation at the same processing position during the two processing cycles and effectively reducing the thermal impact. The planar shapes of both the first and second laser processing paths (path 5 and path 6) consist of a rectangle and line segments. The line segments within the rectangle are used to break up cutting waste during processing, facilitating waste removal after cutting. In this embodiment, the laser grooving parameters can be referenced in Table 1 below.

[0058] Table 1. Reference Table for Laser Grooving Parameters

[0059]

[0060] Other aspects of the method for embedding devices on a circuit board based on laser grooving described in this invention can be found in the prior art and will not be repeated here.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for embedding a device on a circuit board based on laser trenching, characterized by: The method comprises the following steps: S1. Cutting: cutting prepreg into a prepreg base with a preset size; S2. Laser cutting: fixing the base formed after cutting on a laser cutting platform, and processing a through groove penetrating the upper and lower surfaces of the base, so that a sample is obtained after the through groove is processed; S21. According to the maximum groove width D1 required by the specified file, a first cutting is performed on the specified area of the upper surface of the base, so that a first cutting groove with a tapered sidewall is obtained, and the longitudinal section of the first cutting groove is in the shape of a V; S22. According to the groove width D2 required by the specified file, a second cutting is performed downward in the first cutting groove area and penetrates the lower surface of the base, so that a second cutting groove with a vertical sidewall is obtained, and the remaining part of the first cutting groove and the second cutting groove are communicated to form the through groove, wherein D2 is less than D1; the four sidewalls of the first cutting groove are sequentially connected in a tapered manner; and the connection nodes of the two adjacent sidewalls of the second cutting groove are circular arc transition surfaces; S3. Cleaning the groove hole on the sample; S4. Adhesive compression: the lower surface of the sample is first laminated and pre-pressed with adhesive, and then fast pressing is performed according to the specified conditions; S5. Device mounting: according to the design drawing requirements, corresponding devices are respectively mounted in the specified through grooves, and the lower parts of the devices are located in the second cutting groove; S6. Base material compression: the side where the upper surface of the sample with the mounted devices in step S5 is located is first laminated and pre-pressed with a single-sided base material, and then compression is performed according to the specified conditions, so that the insulating medium in the single-sided base material can fill the gap around the device; S7. Adhesive removal: the adhesive on the lower surface of the sample after the base material compression in step S6 is removed; S8. Base material compression: the surface after the adhesive removal in step S7 is first laminated and pre-pressed with a single-sided base material, and then compression is performed according to the specified conditions; S9. Appearance detection: appearance detection is performed, and a sample with a completed device embedded is obtained if the appearance detection is qualified.

2. The method of laser trenching embedded devices on board according to claim 1, wherein: The prepreg is an insulating material.

3. The method of laser trenching embedded devices on board according to claim 1, wherein: In step S2, the prepreg is fixed on the laser cutting platform in an adsorption manner.

4. The method of laser trenching embedded devices on board of claim 1, wherein: In step S21, the laser cutting power of the first cutting is 5w-6w, the laser scanning speed is 200mm / s-300mm / s, the laser cutting frequency is 45KHZ-55KHZ, the laser cutting frequency is 1-4 times, and the Z-axis height is set to 0mm.

5. The method of laser trenching embedded devices on board according to claim 4, wherein: In step S22, the laser cutting power of the second cutting is 3w-3.6w, the laser scanning speed is 250mm / s-350mm / s, the laser cutting frequency is 45KHZ-55KHZ, the laser cutting frequency is 3-6 times, and the Z-axis height is set to-0.001mm.

6. The method of laser trenching embedded devices on board of claim 1, wherein: The difference between D1 and D2 is not less than 10μm.

7. The method of laser trenching embedded devices on board of claim 1, wherein: In step S2, the laser processing path of the first cutting and the laser processing path of the second cutting both include a first path and a second path, the first path is in the shape of a rectangle, the second path is in the shape of a line segment, and the two ends of the second path are connected with the opposite two sides of the rectangle of the first path, respectively.

8. The method of laser trenching embedded devices on board according to claim 7, wherein: In step S2, the first kerf has a length equal to that of the second kerf.

9. The method of laser trenching embedded devices on board of claim 1, wherein: In step S3, the kerf hole is cleaned using a plasma device.

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