A high-precision substrate laser processing method

Abstract

This invention discloses a high-precision substrate laser processing method, belonging to the field of packaging substrate manufacturing technology. The high-precision substrate laser processing method includes: setting multiple circularly arranged positioning targets on a substrate with conductive patterns on its surface; sequentially laminating an additive dielectric film and a protective film onto the substrate surface; capturing the actual coordinates of the multiple positioning targets using a measuring device, and calculating the substrate expansion / contraction value based on the actual and theoretical coordinates of the positioning targets; correcting the theoretical coordinates of blind vias on the substrate surface based on the substrate expansion / contraction value, and performing laser processing based on the corrected coordinates of the blind vias on the substrate surface; capturing images of each positioning target using a measuring device to obtain the processing error; determining whether the processing precision error is less than a set precision value; if yes, removing the protective film on the substrate surface and performing copper plating and via filling electroplating on the additive dielectric film surface; if no, triggering an alarm. This method can prevent substrates with excessive layer misalignment from flowing into subsequent processing, thus avoiding the problem of batch scrap.

Description

Technical Field

[0001] This invention relates to the field of packaging substrate manufacturing technology, and more specifically, to a high-precision substrate laser processing method. Background Technology

[0002] With the rapid development of 5G communication, advanced packaging (FC-BGA, FOWLP), and chiplet technology, substrate linewidth / spacing (L / S) has been rapidly reduced to <8μm / 8μm, via diameter to <20 μm, and via position accuracy required to be ≤5 μm. To meet these requirements, the industry generally uses ultraviolet (UV, 355 nm) or deep ultraviolet (DUV, 266 nm) solid-state lasers, combined with high-speed galvanometer scanning and telecentric F-θ lenses, for laser drilling, grooving, and cutting.

[0003] A search revealed that Chinese patent CN118973140A discloses a low-cost method for fabricating micro PCB laser blind vias. This method involves pressing a subsequently peelable organic film (e.g., dry film) onto the surface of the dielectric film layer on the circuit board. Then, conventional CO2 laser drilling is performed on the surface of the organic film. The laser beam first penetrates the organic film and then penetrates the dielectric film layer until the underlying copper is exposed. After peeling off the upper organic film layer, blind vias with diameters exceeding those of conventional CO2 laser drilling machines can be obtained on the dielectric film layer. Subsequent processes such as adhesive removal, copper plating, and electroplating are then performed to complete the filling of the micro PCB blind vias.

[0004] In the aforementioned processing techniques, it is impossible to measure the layer misalignment accuracy during laser processing. This results in substrates with large layer misalignments being included in subsequent processing steps, leading to batch scrap. Therefore, we propose a high-precision laser processing method for substrates. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] The purpose of this invention is to provide a high-precision substrate laser processing method to solve the problems mentioned in the background art.

[0007] 2. Technical Solution

[0008] This invention is achieved through the following technical solution:

[0009] A high-precision substrate laser processing method includes the following steps:

[0010] S1. Multiple circular positioning targets are disposed on a substrate with conductive patterns on the surface, wherein the positioning targets are made of metal.

[0011] S2. Sequentially laminate the additive dielectric film and the protective film onto the substrate surface;

[0012] S3. The actual coordinates of multiple positioning targets are captured by measuring equipment, and the substrate expansion and contraction value is calculated based on the actual coordinates and theoretical coordinates of the positioning targets; the theoretical coordinates of the blind holes on the substrate surface are obtained, and the theoretical coordinates of the blind holes on the substrate surface are corrected based on the substrate expansion and contraction value to obtain the corrected coordinates of the blind holes on the substrate surface; laser processing is performed based on the corrected coordinates of the blind holes on the substrate surface; the blind holes on the substrate surface include a first blind hole and a second blind hole, both of which penetrate the additive dielectric film and the protective film. The theoretical coordinates of the first blind hole are the same as the actual coordinates of the positioning targets. At least three second blind holes surround the outside of each first blind hole, and the distance between the theoretical coordinates of the first blind hole and the second blind hole is the radius of the positioning target;

[0013] S4. Capture images of each positioning target using measuring equipment, mark the center of the positioning target through the edge of the positioning target exposed by the second blind hole, mark the distance between the center of the positioning target and the center of the first blind hole in the measured image, and obtain the processing error.

[0014] S5. Determine whether the processing accuracy error is less than the set accuracy value; if yes, remove the protective film on the substrate surface and perform copper plating and hole filling on the surface of the additive dielectric film; if no, issue an alarm.

[0015] As an optional solution to the technical solution of this application, in S1, the surface of the substrate is divided into multiple sub-regions, and multiple positioning targets are provided in each sub-region. The positioning targets are distributed at the edge of the pattern of the sub-region.

[0016] As an optional solution to the technical solution of this application, the sub-region is rectangular, and each sub-region is provided with 4 positioning targets, and the side length of the sub-region does not exceed 300mm.

[0017] As an optional solution to the technical solution of this application, step S3 includes the following sub-steps:

[0018] S301. Select a sub-region to be laser drilled as the drilling region, grab all the positioning targets in the drilling region, and calculate the substrate expansion and contraction value based on the actual coordinates and theoretical coordinates of the positioning targets.

[0019] S302. Obtain the theoretical coordinates of all blind holes on the substrate surface within the drilling area, and correct the theoretical coordinates of all blind holes on the substrate surface within the drilling area according to the substrate expansion and contraction value to obtain the corrected coordinates of the blind holes on the substrate surface; perform laser processing according to the corrected coordinates of the blind holes on the substrate surface.

[0020] S303, repeat S301 to S303 until all sub-regions have completed laser drilling.

[0021] As an optional solution to the technical solution in this application, the diameter of the positioning target is between 500μm and 600μm.

[0022] As an optional solution to the technical solution in this application, the diameter of the first blind hole is 50-80μm.

[0023] As an optional solution to the technical solution of this application, each of the first blind holes is surrounded by four second blind holes, the diameter of which is 110-150μm.

[0024] As an optional solution to the technical solution in this application, the thickness of the added dielectric film / protective film between the first blind hole and the second blind hole is not less than 15 μm.

[0025] As an optional solution to the technical solution in this application, the positioning target is made using a process of film application, exposure, development, and etching.

[0026] 3. Beneficial effects

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1) By opening a first blind hole and a second blind hole on the substrate, this application can measure the layer deviation accuracy of laser processing by measuring the distance between the center of the positioning target circle and the center of the first blind hole circle. This avoids the substrate with excessive layer deviation from flowing into the subsequent processing process, which would lead to problems such as batch scrapping of products, wasted costs, and low equipment uptime.

[0029] 2) This application can effectively increase the precision of laser processing by dividing the substrate into multiple sub-regions and calculating the substrate expansion and contraction value by capturing all positioning targets on each sub-region. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the positioning target distribution in a high-precision substrate laser processing method;

[0031] Figure 2 This is a schematic diagram of the first and second blind holes in a high-precision substrate laser processing method;

[0032] Figure 3 This is a schematic diagram of the image captured at the positioning target in a high-precision substrate laser processing method.

[0033] Figure 4 This is a precision testing diagram of existing substrate laser processing methods;

[0034] Figure 5 This is a precision inspection diagram of a high-precision substrate laser processing method;

[0035] In the diagram: 1. Positioning target; 2. First blind hole; 3. Second blind hole. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0037] Please see Figures 1 to 3 This invention provides a high-precision substrate laser processing method, comprising the following steps:

[0038] S1. Multiple circular positioning targets 1 are disposed on a substrate with conductive patterns on the surface, wherein the positioning targets 1 are made of metal.

[0039] S2. A dielectric film and a protective film are sequentially laminated on the outer side of the substrate.

[0040] S3. The actual coordinates of multiple positioning targets 1 are captured by measuring equipment, and the substrate expansion and contraction value is calculated based on the actual coordinates and theoretical coordinates of the positioning targets 1; the theoretical coordinates of the blind holes on the substrate surface are obtained, and the theoretical coordinates of the blind holes on the substrate surface are corrected based on the substrate expansion and contraction value to obtain the corrected coordinates of the blind holes on the substrate surface; laser processing is performed based on the corrected coordinates of the blind holes on the substrate surface; the blind holes on the substrate surface include a first blind hole 2 and a second blind hole 3, both of which penetrate the additive dielectric film and the protective film. The theoretical coordinates of the first blind hole 2 are the same as the actual coordinates of the positioning targets 1. At least three second blind holes 3 surround the outside of each first blind hole 2, and the distance between the theoretical coordinates of the first blind hole 2 and the second blind hole 3 is the radius of the positioning target 1;

[0041] S4. Capture an image of each positioning target 1 using a measuring device, mark the center of the positioning target 1 through the edge of the positioning target 1 exposed by the second blind hole 3, mark the distance between the center of the positioning target 1 and the center of the first blind hole 2 in the measured image, and obtain the processing error.

[0042] S5. Determine if the processing error is less than the set accuracy value; if yes, remove the protective film on the substrate surface and perform copper plating and hole filling on the surface of the additive dielectric film; if no, issue an alarm.

[0043] In this technical solution, the positioning target 1 is preferably made of copper, and the set accuracy value is 8μm. By setting the second blind hole 3, the edge of the positioning target 1 can be exposed. When the image at the positioning target 1 is captured, the center position of the positioning target 1 can be accurately obtained. This avoids the obstruction of the dielectric film and protective film on the surface of the positioning target 1, which would make it difficult to determine the center position of the positioning target 1 and affect the measurement accuracy of the processing error.

[0044] Preferably, in S1, the substrate surface is divided into multiple sub-regions, each sub-region having multiple positioning targets 1 distributed along the edge of the sub-region's shape; the sub-regions are rectangular, each sub-region having four positioning targets 1, and the side length of each sub-region not exceeding 300mm. Figure 1 As shown.

[0045] Preferably, step S3 includes the following sub-steps:

[0046] S301. Select a sub-region to be laser drilled as the drilling region, grab all the positioning targets 1 in the drilling region, and calculate the substrate expansion and contraction value based on the actual coordinates and theoretical coordinates of the positioning targets 1.

[0047] S302. Obtain the theoretical coordinates of all blind holes on the substrate surface within the drilling area, and correct the theoretical coordinates of all blind holes on the substrate surface within the drilling area according to the substrate expansion and contraction value to obtain the corrected coordinates of the blind holes on the substrate surface; perform laser processing according to the corrected coordinates of the blind holes on the substrate surface.

[0048] S303, repeat S301 to S303 until all sub-regions have completed laser drilling.

[0049] In S302, the substrate expansion / contraction value is calculated using the following formula:

[0050] ; ;

[0051] ; ;

[0052] ; ;

[0053] ; ;

[0054]

[0055]

[0056] like ,but ;

[0057] otherwise ;

[0058] like ,but ;

[0059] otherwise ;

[0060] ;

[0061] ;

[0062] In the formula, , The scaling values ​​for the x and y coordinates of the substrate laser processing; , Let be the theoretical coordinates of the i-th positioning target 1 within the drilling area; , For the theoretical center of gravity coordinates; , The measured coordinates of the i-th positioning target 1 within the drilling area; , The coordinates of the measured center of gravity are given; N is set to 4, which represents the total number of positioning targets 1 within the borehole area.

[0063] In this technical solution, by partitioning the substrate, the accuracy of laser drilling can be effectively increased, thereby increasing the product yield.

[0064] In a preferred embodiment of this application, the diameter of the positioning target 1 is between 500 μm and 600 μm.

[0065] In a preferred embodiment of this application, the diameter of the first blind hole 2 is 50-80 μm, preferably 60 μm.

[0066] As a preferred embodiment of this application, each of the first blind holes 2 is surrounded by four second blind holes 3, the diameter of the second blind holes 3 being 110-150μm, preferably 120μm.

[0067] Preferably, the thickness of the dielectric film / protective film layer between the first blind hole 2 and the second blind hole 3 is not less than 15 μm, so as to avoid the second blind hole 3 affecting the shape of the first blind hole 2 when it is opened.

[0068] Preferably, the positioning target 1 is made using a process of film application, exposure, development, and etching.

[0069] According to DOE experimental verification data, the average accuracy measured using existing processing methods is 5.6 μm, indicating poor accuracy uniformity. Figure 4 As shown, the average processing accuracy of the new technology is 3.4μm, with relatively stable accuracy uniformity, achieving effective improvement. Furthermore, it allows for precise monitoring of the product processing accuracy offset between layers and the accuracy stability of the laser processing equipment. Figure 5 As shown.

[0070] exist Figure 4 and Figure 5In this diagram, the `avg` parameter represents the average accuracy of laser blind hole measurements across multiple samples. The horizontal axis represents the sample number, and the vertical axis represents the laser blind hole measurement accuracy. For each sample, multiple laser blind holes are selected for accuracy measurements, meaning that each horizontal axis position has multiple vertical axes. On the vertical axis, `UCL` (up control limit) represents the factory-required accuracy, and `USL` (up specofoculation limit) represents the end-customer-required accuracy. Among the multiple vertical axes corresponding to the horizontal axis positions, the lower boundary of the rectangle represents the first quartile of the measurement data set, and the upper boundary represents the third quartile. The center point of the rhombus represents the mean of the measurement data within the rectangle, and the top and bottom vertices of the rhombus represent the 95% confidence interval of that mean.

Claims

1. A high-precision substrate laser processing method, characterized by: The method comprises the following steps: S1, arranging a plurality of positioning targets (1) in a circular arrangement on a substrate having a conductive pattern on the surface layer, the positioning targets (1) being made of metal; S2, sequentially pressing a build-up dielectric film and a protective film on the surface of the substrate; S3, capturing the actual coordinates of the plurality of positioning targets (1) by a measuring device, and calculating the substrate expansion value according to the actual coordinates and the theoretical coordinates of the positioning targets (1); obtaining the theoretical coordinates of the substrate surface layer blind holes, and correcting the theoretical coordinates of the substrate surface layer blind holes according to the substrate expansion value to obtain the corrected coordinates of the substrate surface layer blind holes; According to the corrected coordinates of the substrate surface layer blind holes, laser processing is performed; the substrate surface layer blind holes include first blind holes (2) and second blind holes (3), the first blind holes (2) and the second blind holes (3) both penetrate the build-up dielectric film and the protective film, the theoretical coordinates of the first blind holes (2) are the same as the actual coordinates of the positioning targets (1), and each first blind hole (2) is surrounded by at least three second blind holes (3), the distance between the theoretical coordinates of the first blind holes (2) and the second blind holes (3) is the radius of the positioning target (1); S4, capturing the image at each positioning target (1) by a measuring device, marking the center of the positioning target (1) through the edge of the positioning target (1) exposed by the second blind hole (3), measuring the distance between the center of the positioning target (1) and the center of the first blind hole (2) in the image to obtain the processing error; S5, determining whether the processing precision error is less than the set precision value; if yes, removing the protective film on the surface of the substrate and performing copper deposition and hole filling electroplating on the surface of the build-up dielectric film; if no, an alarm is given.

2. The high-precision substrate laser processing method of claim 1, wherein: In S1, the surface of the substrate is divided into a plurality of sub-regions, and a plurality of positioning targets (1) are arranged in each sub-region, and the positioning targets (1) are distributed at the edges of the patterns in the sub-regions.

3. The high-precision substrate laser processing method of claim 2, wherein: The sub-regions are arranged in a rectangular shape, and four positioning targets (1) are arranged in each sub-region, and the side length of the sub-region is not more than 300 mm.

4. The high-precision substrate laser processing method of claim 2, wherein: The S3 comprises the following sub-steps: S301, selecting a sub-region to be laser drilled as a drilling region, capturing all the positioning targets (1) in the drilling region, and calculating the substrate expansion value according to the actual coordinates and the theoretical coordinates of the positioning targets (1); S302, obtaining the theoretical coordinates of all the substrate surface layer blind holes in the drilling region, correcting the theoretical coordinates of all the substrate surface layer blind holes in the drilling region according to the substrate expansion value to obtain the corrected coordinates of the substrate surface layer blind holes, and performing laser processing according to the corrected coordinates of the substrate surface layer blind holes; S303, repeating S301 to S303 until laser drilling processing is completed in all the sub-regions.

5. The method of claim 1, wherein the substrate is a glass substrate. The diameter of the positioning target (1) is between 500 μm and 600 μm.

6. The method of claim 1, wherein: The diameter of the first blind hole (2) is 50-80 μm.

7. The method of claim 1, wherein the substrate is a glass substrate. Each first blind hole (2) is surrounded by four second blind holes (3), and the diameter of the second blind hole (3) is 110-150 μm.

8. The method of claim 1, wherein the substrate is a high-precision substrate. The thickness of the build-up dielectric film / protective film between the first blind hole (2) and the second blind hole (3) is not less than 15 μm.

9. The method of claim 1, wherein the substrate is a glass substrate. The positioning target (1) is made by a film pasting, exposure, development and etching process.

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