Laser drilling method for FOPLP packaging

Abstract

The embodiment of the application discloses a kind of for FOPLP package in laser drilling processing method. By the embodiment of the application, when processing elliptical blind hole, it is divided into outer contour processing and internal filling, avoid the heat accumulation and deformation of once processing. Adopt layered processing, correct center boss and edge recess layer by layer, ensure hole bottom flatness. Before processing, the outer contour is divided into a plurality of processing sections connected head to tail, the number of sections is set according to the contour accuracy, to ensure that the edge is smooth, reduce the heat influence, and provide boundary for internal filling. The scanning pitch of internal filling is determined by the spot diameter and the lap rate, to realize uniform energy superposition, remove consistent depth. The application can effectively eliminate the boss recess, improve the flatness, reduce the carbonization residue, and protect the subsequent electroplating quality by the outer contour segmentation and the filling of controllable lap rate, combined with layered coordination, so that each layer contour and internal removal depth are consistent.

Description

Technical Field

[0001] This application relates to the field of FOPLP packaging technology, and more particularly to a laser drilling method for FOPLP packaging. Background Technology

[0002] In FOPLP packaging, it is often necessary to directly laser-drill elliptical blind holes into the molding compound (epoxy resin base molding compound). However, current laser drilling processes have the following problems: 1. Uneven laser energy distribution, with excessively high energy at the center, causes molten material to be recast and accumulate at the bottom of the hole due to overburning, forming a protrusion with a height of about 10–20 μm; at the same time, the energy at the edge is too weak, resulting in insufficient ablation, and the bottom of the hole eventually presents a convex shape of "high in the middle and low around the edges".

[0003] Second, the large difference in scanning energy accumulation between the major and minor axes of the ellipse causes the bottom of the hole to undulate along the major and minor axes, resulting in a wavy and uneven surface.

[0004] Third, epoxy resin molding compound has a significant thermal effect, which can easily produce molten protrusions and carbonized residues during processing, resulting in large roughness at the bottom of the hole.

[0005] Fourth, the fixed laser spot diameter and solidified process parameters make it impossible to achieve precise depth control in layers, and also impossible to dynamically match the energy distribution requirements of the bottom of the elliptical hole, further exacerbating problems such as insufficient edge ablation, large heat-affected zone, and severe carbonization.

[0006] The above-mentioned problems together make it difficult to control the flatness of the hole bottom, resulting in an irregular overall shape of the blind hole, which in turn affects the quality of subsequent chemical copper plating and causes defects such as electroplating voids. Summary of the Invention

[0007] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a laser drilling method for FOPLP packaging, addressing the current problems of unstable control over the flatness of the hole bottom and irregular overall shape of blind holes.

[0008] This application provides a laser drilling method for FOPLP packaging, comprising: dividing the outer contour of a target elliptical blind hole into multiple interconnected contour processing segments, and generating a filling path inside the outer contour; dividing the target elliptical blind hole into multiple processing layers according to the total processing depth; within each processing layer, controlling a laser beam to scan all paths of the same type sequentially with a first processing parameter until the path of that type is scanned completely; switching to a second processing parameter to scan all paths of another type sequentially until the path of that type is scanned completely; wherein, the type refers to the outer contour processing segment or the filling path, and the first processing parameter and the second processing parameter are different; the spacing between adjacent scanning trajectories of the filling path is determined based on the laser beam spot diameter and a preset overlap rate; and, after each processing layer is processed, the material removal depth of the outer contour region and the inner region is consistent.

[0009] Based on the aforementioned laser drilling method for FOPLP packaging, the processing of elliptical blind holes is divided into outer contour processing and internal filling processing. This avoids the severe heat accumulation and contour deformation caused by continuous processing of the entire area in traditional processes. Simultaneously, based on the total processing depth, the target elliptical blind hole is divided into multiple processing layers. A layered processing approach allows for gradual correction of the height difference between the central boss and the edge recess at the bottom of the hole within each layer, ultimately ensuring the flatness of the hole bottom meets requirements. Before formal processing, the outer contour of the target elliptical blind hole is divided into multiple interconnected contour processing segments. The specific number of segments is determined based on a preset contour accuracy to ensure the smoothness of the contour edges and reduce thermal impact. Simultaneously, the delineation of the outer contour provides a precise boundary for the generation of the internal filling path. Subsequently, a filling path is generated within the outer contour, and the spacing between adjacent scanning trajectories in the filling path is determined based on the laser beam spot diameter and a preset overlap rate. This allows the energy of adjacent scanning trajectories to gradually superimpose, forming a uniform energy distribution envelope within the elliptical hole, thereby achieving a uniform material removal depth.

[0010] In one or more embodiments of the laser drilling method for FOPLP packaging described above, within each processing layer, a first processing parameter is used to scan along the filling path, and then a second processing parameter is used to scan along each of the contour processing segments.

[0011] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the laser power of the first processing parameter is greater than the laser power of the second processing parameter.

[0012] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the plurality of processing layers include a first processing layer and a second processing layer; the step of scanning along the filling path with a first processing parameter includes: controlling the laser beam to scan the first processing layer along the filling path with a first laser power and a first moving speed; and controlling the laser beam to scan the second processing layer along the filling path with a second laser power and a second moving speed.

[0013] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the first laser power is 0.8-1.2W and the first moving speed is 80-120mm / s; the second laser power is 0.2-0.4W and the second moving speed is 240-300mm / s.

[0014] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the first processing layer and the second processing layer are each scanned at least twice.

[0015] In one or more embodiments of the laser drilling process for FOPLP packaging described above, the removal depth of the first processing layer accounts for 80-90% of the total processing depth.

[0016] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the filling path consists of multiple parallel and equally spaced straight processing segments, with adjacent straight processing segments connected end-to-end by connecting segments to form a continuous filling path.

[0017] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the preset overlap rate is 10%-20%, and the spacing S between adjacent scanning trajectories satisfies: S=Dx(1-R), where D is the spot diameter and R is the preset overlap rate.

[0018] In one or more embodiments of the laser drilling method for FOPLP packaging described above, the ratio of the major axis to the minor axis of the target elliptical blind hole is 1.2-2.5, and the ratio of the total machining depth to the minor axis is 0.8-1.5.

[0019] The above-described one or more embodiments of this application have at least one or more of the following beneficial effects: By decomposing the processing of elliptical blind holes into segmented processing of the outer contour and uniform filling processing with controllable internal overlap, and combining it with a layered collaborative scanning strategy, the material removal depth of the inner contour area and the inner area of ​​each processing layer is kept consistent. This achieves the technical effects of effectively eliminating the central boss and edge depression at the bottom of the hole, significantly improving the flatness of the bottom of the hole, reducing carbonization and molten residue, and ensuring the quality of subsequent chemical copper plating and electroplating.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein: Figure 1 This is a flowchart illustrating a laser drilling process for FOPLP packaging, provided in an embodiment of this application. Figure 2 This is a schematic diagram provided in an embodiment of the present application for illustrating the filling path and contour processing segment; Figure 3 It is an elliptical blind hole pattern processed using existing technology; Figure 4 This is an elliptical blind hole diagram provided in an embodiment of this application.

[0022] Explanation of reference numerals in the attached figures: 1. Contour processing segment; 2. Fill path; 21. Straight line processing segment. Detailed Implementation

[0023] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0024] Current laser drilling technology makes it difficult to control the flatness of the hole bottom, resulting in irregular overall shape of blind holes, which in turn affects the quality of subsequent chemical copper plating and causes defects such as electroplating voids.

[0025] Therefore, this application presents a novel laser drilling method for FOPLP packaging. When processing elliptical blind holes, this application divides the process into outer contour processing and internal filling processing, avoiding the severe heat accumulation and contour deformation caused by continuous processing of the entire area in traditional processes. Simultaneously, based on the total processing depth, the target elliptical blind hole is divided into multiple processing layers. This layered processing method allows for gradual correction of the height difference between the central boss and the edge recess at the bottom of the hole within each layer, ultimately achieving the required flatness of the hole bottom. Before formal processing, the outer contour of the target elliptical blind hole is divided into multiple interconnected contour processing segments. The specific number of segments is determined based on a preset contour accuracy to ensure the smoothness of the contour edges and reduce thermal impact. Simultaneously, the delineation of the outer contour provides a precise boundary for the generation of the internal filling path. Subsequently, a filling path is generated within the outer contour, and based on the laser beam spot diameter and a preset overlap rate, the spacing between adjacent scanning trajectories in the filling path is determined. This allows the energy of adjacent scanning trajectories to be smoothly superimposed, forming a uniform energy distribution envelope within the elliptical hole, thereby achieving a uniform material removal depth. Compared to existing technologies, this application decomposes the processing of elliptical blind holes into segmented processing of the outer contour and uniform filling processing with controllable internal overlap rate. Combined with a layered collaborative scanning strategy, it ensures that the material removal depth of the inner contour area and the inner area of ​​each processing layer remains consistent. This achieves the technical effects of effectively eliminating the central boss and edge depression at the bottom of the hole, significantly improving the flatness of the bottom of the hole, reducing carbonization and molten residue, and ensuring the quality of subsequent chemical copper plating and electroplating.

[0026] The present application will be described in detail below through specific embodiments.

[0027] Reference Figures 1 to 4 As shown in the figure, this application provides a laser drilling method for FOPLP packaging, the method comprising: S100: Divide the outer contour of the target elliptical blind hole into multiple contour processing segments connected end to end, and generate a filling path inside the outer contour.

[0028] It is understood that the contour processing segment 1 can be a straight line segment or an arc segment. In this embodiment, to reduce processing difficulty and improve processing efficiency, the contour processing segment 1 is preferably a straight line segment. The more contour processing segments 1 there are, the smoother the outer contour of the target elliptical blind hole will be.

[0029] In some examples, the length of each contour processing segment 1 can be kept consistent to simplify path planning. In other examples, the length of each processing segment can be adaptively adjusted according to the curvature variation of the elliptical contour: longer processing segments are used in areas with lower curvature, such as the endpoints of the major axis, to improve efficiency; shorter processing segments are used in areas with higher curvature, such as the endpoints of the minor axis, to ensure contour accuracy. This adaptive segmentation method can balance overall processing efficiency while ensuring the smoothness of the outer contour.

[0030] S200. Based on the total machining depth, the target elliptical blind hole is divided into multiple machining layers.

[0031] In some examples, the thickness of each processing layer can be different to balance processing efficiency and processing accuracy. For example, the initial processing layer can be set to a larger thickness to quickly remove most of the material and improve processing efficiency; subsequent processing layers can be set to a smaller thickness to finely finish the flatness of the hole bottom and improve processing accuracy.

[0032] S300. Within each processing layer, the laser beam is controlled to scan all paths of the same type sequentially using the first processing parameters until the path of that type has been scanned.

[0033] S400, switch to the second processing parameter, and scan all paths belonging to another type in sequence until the other type of paths have been scanned.

[0034] Among them, the type refers to the outer contour processing segment 1 or the filling path 2, and the first processing parameter and the second processing parameter are different; The spacing between adjacent scanning trajectories of filling path 2 is determined based on the laser beam spot diameter and the preset overlap ratio; Furthermore, after each processing layer is completed, the material removal depth of the outer contour area and the inner area is consistent.

[0035] In some examples, the processing sequence of the outer contour and interior of the target elliptical blind hole can be flexibly adjusted according to actual requirements. In this implementation, within each processing layer, a scan is first performed along the fill path 2 using the first processing parameter, and then a scan is performed along each contour processing segment 1 using the second processing parameter. By processing the interior area of ​​the target elliptical blind hole first, most of the material is removed; then the outer contour is processed to refine the elliptical boundary and improve the smoothness and clarity of the outer contour edge. It should be noted that the laser must be turned off when switching from processing the interior to processing the outer contour.

[0036] Those skilled in the art will understand that the spacing between adjacent scanning trajectories of filling path 2 is not arbitrarily set, but is precisely calculated based on the laser spot diameter and preset overlap rate. The purpose is to allow the energy of adjacent scanning trajectories to be smoothly superimposed, forming a uniform energy distribution envelope inside the elliptical hole, thereby achieving a uniform material removal depth.

[0037] In some examples, the preset overlap rate is 10%-20%, and the spacing S between adjacent scanning trajectories satisfies: S=Dx(1-R), where D is the spot diameter and R is the preset overlap rate.

[0038] Furthermore, in some examples, the laser power of the first processing parameter is greater than the laser power of the second processing parameter. By setting the laser power when processing the outer contour to be lower than that when processing the interior, it is possible to trim the elliptical contour boundary while avoiding damage to the flatness of the already processed internal area due to excessive power, thereby better ensuring the overall flatness of the hole bottom.

[0039] In some examples, multiple processing layers include a first processing layer and a second processing layer. Scanning along fill path 2 with the first processing parameters first includes: The laser beam is controlled to scan the first processing layer along the filling path 2 at a first laser power and a first moving speed; The laser beam is controlled to scan the second processing layer along the filling path 2 with a second laser power and a second moving speed.

[0040] By using different laser powers and moving speeds for different processing layers, the processing requirements of each layer can be adapted, thus balancing processing accuracy and processing efficiency.

[0041] In this embodiment, the first laser power is 0.8-1.2W, and the first moving speed is 80-120mm / s; the second laser power is 0.2-0.4W, and the second moving speed is 240-300mm / s. Furthermore, the laser beam frequency is 40-60kHz.

[0042] In some examples, the removal depth of the first processing layer accounts for 80% to 90% of the total processing depth. In this embodiment, the removal depth of the first processing layer accounts for 85% of the total processing depth, and the removal depth of the second processing layer accounts for 15% of the total processing depth.

[0043] The above parameter configuration enables the first processing layer to achieve slow deep drilling with high power and low scanning speed, ensuring that the light spots fully overlap and form a uniform and flat removal bottom surface, avoiding local deep pits or material residues caused by excessive scanning speed; the second processing layer uses low power and high scanning speed for rapid fine finishing, further reducing the roughness of the hole bottom, removing residual material accumulation, and finally obtaining a flat hole bottom that meets the flatness requirements.

[0044] In some examples, the first processing layer and the second processing layer are each scanned at least twice. In this embodiment, the first processing layer and the second processing layer are scanned twice.

[0045] By performing multiple scans along the same path, residual material can be removed successively, effectively reducing the roughness of the hole bottom and smoothing the surface, thereby further improving the flatness of the hole bottom. It should be understood that the filling path 2 includes equidistant zigzag paths, equidistant planar spiral paths, equidistant concentric circle paths, and equidistant straight lines. In this embodiment, the filling path 2 consists of multiple parallel and equally spaced straight processing segments 21. Adjacent straight processing segments 21 are connected end-to-end by connecting segments to form a continuous filling path 2, thereby avoiding idle travel during processing and improving processing efficiency.

[0046] The connecting section is used to smoothly transition between the straight machining sections 21. Its shape can be an arc or a slanted line to reduce energy accumulation at the path turnaround point and avoid local overheating caused by sudden stops and starts of the motion axis, thereby further reducing the thermal impact.

[0047] Furthermore, in this embodiment, each straight machining segment 21 is arranged linearly along the short axis direction.

[0048] In some examples, the ratio of the major axis to the minor axis of the target elliptical blind hole is 1.2-2.5, and the ratio of the total machining depth to the minor axis is 0.8-1.5. For elliptical blind holes with the above geometric characteristics, this method can more effectively control the energy uniformity at the bottom of the hole, achieve layered collaborative leveling, and thus produce elliptical blind holes with high bottom flatness accuracy.

[0049] Specifically, when machining elliptical blind holes, the process is divided into outer contour machining and internal filling machining, avoiding the severe heat accumulation and contour deformation caused by continuous machining of the entire area in traditional processes. Simultaneously, based on the total machining depth, the target elliptical blind hole is divided into multiple machining layers. This layered machining approach allows for gradual correction of the height difference between the central boss and the edge recess at the bottom of the hole within each layer, ultimately ensuring the flatness of the hole bottom meets the requirements. Before formal machining, the outer contour of the target elliptical blind hole is divided into multiple interconnected contour machining segments 1. The specific number of segments is determined based on the preset contour accuracy to ensure the smoothness of the contour edges and reduce the thermal impact. Simultaneously, the delineation of the outer contour provides a precise boundary for the generation of the internal filling path 2. Subsequently, the filling path 2 is generated within the outer contour, and the spacing between adjacent scanning trajectories in the filling path 2 is determined based on the laser beam spot diameter and the preset overlap rate. This allows the energy of adjacent scanning trajectories to be smoothly superimposed, forming a uniform energy distribution envelope within the elliptical hole, thereby achieving a uniform material removal depth. Compared to existing technologies, this application decomposes the processing of elliptical blind holes into segmented processing of the outer contour and uniform filling processing with controllable internal overlap rate. Combined with a layered collaborative scanning strategy, it ensures that the material removal depth of the inner contour area and the inner area of ​​each processing layer remains consistent. This achieves the technical effects of effectively eliminating the central boss and edge depression at the bottom of the hole, significantly improving the flatness of the bottom of the hole, reducing carbonization and molten residue, and ensuring the quality of subsequent chemical copper plating and electroplating.

[0050] For example, using the layered processing method described above, the major axis of the target elliptical blind hole is 200 μm, the minor axis is 135 μm, and the total depth is 140 μm. The laser spot diameter is 25 μm, and the filling path 2 consists of 6 parallel and equally spaced straight processing segments 21. The overlap area between adjacent straight processing segments 21 is 3 μm, and the overlap rate is approximately 12%.

[0051] Within each processing layer, the first processing parameters include: laser power 1.2W, moving speed 200mm / s, and internal filling scan 3 times; the second processing parameters include: laser power 0.6W, moving speed 100mm / s, and outer contour scan 1 time.

[0052] Combined with appendix Figure 3 and attached Figure 4 As shown, attached Figure 3 For elliptical blind holes manufactured using existing processes, attached Figure 4 The image shows an elliptical blind hole processed using this method with the aforementioned data. It is clearly evident that after using this method, the central boss at the bottom of the hole is completely eliminated, and the bottom of the hole is smooth with no undulations or wavy unevenness. Furthermore, the defect rate of subsequent electroplating voids and poor soldering is reduced from 10% to 1%.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0055] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for laser drilling processing in a FOPLP package, characterized in that, include: The outer contour of the target elliptical blind hole is divided into multiple contour processing segments connected end to end, and a filling path is generated inside the outer contour. Based on the total machining depth, the target elliptical blind hole is divided into multiple machining layers; Within each processing layer, the laser beam is controlled to scan all paths of the same type sequentially with the first processing parameters until all paths of that type have been scanned. Switch to the second processing parameter and scan all paths belonging to the other type in sequence until the other type of paths have been scanned; Wherein, the type refers to the outer contour processing segment or the filling path, and the first processing parameters and the second processing parameters are different; The spacing between adjacent scanning trajectories of the filling path is determined based on the laser beam spot diameter and a preset overlap ratio; Furthermore, after each processing layer is completed, the material removal depth of the outer contour area and the inner area is consistent.

2. The method for laser drilling process in FOPLP package according to claim 1, wherein, Within each of the processing layers, a first processing parameter is used to scan along the filling path, and then a second processing parameter is used to scan along each of the contour processing segments.

3. The laser drilling method for FOPLP packaging according to claim 2, characterized in that, The laser power of the first processing parameter is greater than the laser power of the second processing parameter.

4. The laser drilling method for FOPLP packaging according to claim 2, characterized in that, The plurality of processing layers includes a first processing layer and a second processing layer; The step of first scanning along the filling path using the first processing parameters includes: The laser beam is controlled to scan the first processing layer along the filling path at a first laser power and a first moving speed; The laser beam is controlled to scan the second processing layer along the filling path at a second laser power and a second moving speed.

5. The laser drilling method for FOPLP packaging according to claim 4, characterized in that, The first laser power is 0.8-1.2W, and the first moving speed is 80-120mm / s; The second laser power is 0.2-0.4W, and the second moving speed is 240-300mm / s.

6. The laser drilling method for FOPLP packaging according to claim 4, characterized in that, The first processing layer and the second processing layer are each scanned at least twice.

7. The laser drilling method for FOPLP packaging according to claim 4, wherein the removal depth of the first processing layer accounts for 80-90% of the total processing depth.

8. The laser drilling method for FOPLP packaging according to claim 1, characterized in that, The filling path consists of multiple parallel and equally spaced straight processing segments, with adjacent straight processing segments connected end to end by connecting segments to form a continuous filling path.

9. The laser drilling method for FOPLP packaging according to claim 1, characterized in that, The preset overlap rate is 10%-20%, and the spacing S between adjacent scanning trajectories satisfies: S=Dx(1-R), where D is the spot diameter and R is the preset overlap rate.

10. The laser drilling method for FOPLP packaging according to claim 1, wherein the ratio of the major axis to the minor axis of the target elliptical blind hole is 1.2-2.5, and the ratio of the total machining depth to the minor axis is 0.8-1.5.

Images