Refined bonding pad processing method for high-density and small-spacing BGA (Ball Grid Array) packaging plate

Abstract

The invention discloses a refined pad processing method for a high-density and small-spacing BGA packaging board, and relates to the technical field of semiconductor processing, the method comprises the following steps: listing possible physical states of all BGA pads, then executing different compensation, cutting and solder resist windowing strategies according to different physical states, and through systematic comprehensive consideration, on one hand, on the other hand, on the other hand, on the other hand, on the other hand, on the other hand, on the other hand, on the other hand; on the one hand, it is ensured that the finally-formed bonding pad does not cause damage and interference to an original BGA circuit, on the other hand, it is ensured to the maximum extent that the final effective size of various bonding pads of the BGA after etching meets the error range, the reliability of later welding is reduced, corresponding compensation, cutting and solder mask windowing proportion operation data are given for different types in the whole scheme, and the accuracy of the BGA bonding pad is improved. Therefore, the whole scheme is enabled to have the feasibility.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing technology, and in particular to a refined pad processing method for high-density, small-pitch BGA package boards. Background Technology

[0002] In traditional PCB manufacturing, high-density, small-pitch BGA pads are generally treated with a uniform compensation method or a simple cutting method. For complex BGA pads, the uniform compensation method is used, which means that all BGA pads use the same compensation value. This "one-size-fits-all" strategy completely ignores the physical differences between different types of pads during the etching process. The simple cutting method is used when the spacing is insufficient and routing is not possible. The pads that block the routing are simply cut, but no consideration is given to how to compensate for the pad area lost due to cutting.

[0003] Meanwhile, existing technologies either focus only on line compensation or solder mask adjustment, lacking a systematic solution that considers both and the routing scheme together. They usually adopt a simple and crude method of enlarging the whole and then cutting, but do not consider the area loss caused by cutting, resulting in low yield and high quality risk. To address this, a refined pad processing method for high-density, small-pitch BGA package boards is provided to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a refined pad processing method for high-density, small-pitch BGA package boards to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for refined pad processing of a high-density, small-pitch BGA package board, comprising the following steps: S1. Obtain BGA pad images and determine the BGA pad type based on the BGA pad images; S2. Based on the concept of effective constant control of BGA pad area, differentiated BGA pad collaborative processing strategies are designed for different BGA pad types, including area compensation pre-increase, area cutting and solder mask opening enlargement. S3. Determine the processing dimensions based on the BGA pad dimensions and execute the processing strategy in sequence; S4. Measure and calculate the effective BGA pad area and confirm that it is qualified.

[0006] Preferably, in step S1, based on the final shape of the pads after etching and the solder mask coverage, the BGA pads are classified into three core types: isolated BGA pads after etching, BGA pads located on large copper surfaces after etching, and BGA pads connected to conductors or local copper surfaces after etching.

[0007] Preferably, in step S2, differentiated processing strategies are implemented for different types of circuit patterns and solder mask patterns during processing, so that the final effective BGA pad area is increased. ,in For the area after processing, To design the standard area.

[0008] Preferably, in step S2, the detailed execution strategy includes: S21. For isolated BGA pads after etching, an area compensation + cutting strategy is adopted. S22. For BGA pads located on the large copper surface after etching, a strategy of increasing the solder mask opening is adopted. S23. For BGA pads that are connected to conductors or local copper surfaces after etching, adopt the strategy of area compensation + cutting + increasing solder mask opening.

[0009] Preferably, in step S21, isolated BGA pads are classified according to their forming method, including: S211, Original Isolated BGA Pads: For pads that are initially isolated, the overall fabrication area of ​​the pad is increased by 12% during processing, so that the area of ​​the pad after etching is ≥ ; S212. After cutting, the BGA pads become isolated. For these pads with insufficient spacing, the overall fabrication area of ​​the pads is increased by 12%, and then cut on one or both sides. The total cutting amount is... Average finished pad area ≥ .

[0010] Preferably, in step S22, for the BGA pads located on the large copper surface after etching, the solder mask openings on the large copper surface are increased by 7.5% overall based on the original design, so that the area of ​​the etched pads is ≥ .

[0011] Preferably, in step S23, the BGA pads that are connected to the conductors or local copper surfaces after etching are classified according to cutting characteristics, including: S231. For inline pads without cutters, the overall BGA circuit layer is increased by 8% to 10%, and the corresponding BGA pad solder mask opening is increased by 5% on one side based on the original design, so that the average finished pad area after etching is ≥ ; S232. For pads on the line with single-sided clipping, where the BGA spacing is insufficient, the overall BGA pads on the circuit layer are increased by 10%, and then 42% to 9.2% of the pads are clipped on one side. Finally, the solder mask opening is increased by 5% to 15% on one side based on the original design, so that the average pad area after etching is ≥ ; S233. For the pads on the line where the BGA spacing is insufficient, increase the overall size of the BGA pads on the circuit layer by 10%, then reduce the pad size by 42% to 9.2% on one side. Finally, increase the solder mask opening by 10%-20% on one side based on the original design, so that the average pad area after etching is ≥ .

[0012] Preferably, for pads on both sides of the line with a cut-out shape, a teardrop is added at the connection between the pad and the trace to enhance connection reliability when the trace width is ≤4mil.

[0013] Preferably, in step S3, during the execution of the processing strategy, the order of first compensating, then cutting, and finally increasing the solder mask opening is always followed. When the pad size is increased, pre-compensation is performed with the original preset pad position as the center. During the cutting process, cutting control is performed based on the distance between the cutting position and the line to ensure that sufficient distance is maintained between the cutting position and the line after cutting. At the same time, the area after cutting is within the error range of the standard area. The distance between the cutting position and the center of the circle is calculated based on the area difference to ensure cutting accuracy. When the solder mask opening is increased, if the increased opening area does not overlap with the BGA line, the opening is expanded outward from the original preset opening position as the center; if there is overlap, the opening center position is adjusted to the side away from the overlap.

[0014] Preferably, in step S4, a 4K digital microscope system is used to acquire pad images, which are then imported into image analysis software for actual area analysis and calculation to determine the pass rate.

[0015] The technical effects and advantages of this invention are as follows: This refined pad processing method for high-density, small-pitch BGA packages involves listing all possible physical states of BGA pads and then implementing different compensation, cutting, and solder mask opening strategies based on these different physical states. Through systematic and comprehensive consideration, this method ensures that the final formed pads will not damage or interfere with the original BGA circuitry. Furthermore, it maximizes the assurance that the final effective dimensions of various BGA pads after etching meet the tolerance range, reducing the reliability of subsequent soldering. The entire solution provides corresponding compensation, cutting, and solder mask opening ratio operation data for different types to ensure its feasibility. Attached Figure Description

[0016] Figure 1 This is a flowchart of the refined pad processing method of the present invention; Figure 2 This is a schematic diagram illustrating the fine classification of pad types corresponding to the pad collaborative processing strategy of this invention; Figure 3This is a schematic diagram of the pad type style of the present invention; Figure 4 This is a line graph showing the ratio of the area of ​​the original isolated BGA pad after etching to the preset area under different compensation amounts. Figure 5 This is a schematic diagram showing the state types of isolated BGA pads after cutting according to the present invention; Figure 6 This is a line graph showing the ratio of the area of ​​isolated BGA pads after etching to the preset area under different compensation and cutting amounts according to the present invention. Figure 7 This is a line graph showing the ratio of the area after etching to the preset area for different window increments of isolated windowed pads on the copper surface of the present invention. Figure 8 The line graph shows the ratio of the area after etching to the preset area for different overall compensation and different solder resist openings of the online pad without cutting disc in this invention. Figure 9 The line graph represents the ratio of the area after etching to the preset area for different overall compensation and different solder resist openings of the online pads in the single-sided chipping process of this invention. Figure 10 The line graph represents the ratio of the area after etching to the preset area for different overall compensation and different solder resist openings of the online pads in the double-sided chipping device of this invention; Figure 11 This diagram illustrates three states of BGA pads connected to conductors or local copper surfaces after etching, as per the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figures 1-11 The method for refined pad processing of a high-density, small-pitch BGA package board, as shown, includes the following steps: S1. Obtain BGA pad images and confirm BGA pad types based on the BGA pad images. This process classifies BGA pads into three core types based on the final shape of the pads after etching and the solder mask coverage: isolated BGA pads after etching, BGA pads located on large copper surfaces after etching, and BGA pads connected to conductors or local copper surfaces after etching.

[0019] S2. Based on the concept of constant effective BGA pad area control, differentiated BGA pad collaborative processing strategies are designed for different BGA pad types. These include area compensation pre-increase, area trimming, and increased solder mask opening. For different types, differentiated processing strategies are executed during the processing of circuit patterns and solder mask patterns to ensure the final effective BGA pad area... ,in For the area after processing, To design a standard area, the detailed implementation strategy includes; S21. An area compensation + cutting strategy is adopted for isolated BGA pads after etching. The isolated BGA pads are classified according to their forming method. S211, Original Isolated BGA Pads: For pads that are initially isolated, the overall fabrication area of ​​the pad is increased by 12% during processing, so that the area of ​​the pad after etching is ≥ ; S212. After cutting, the BGA pads become isolated. For these pads with insufficient spacing, the overall fabrication area of ​​the pads is increased by 12%, and then cut on one or both sides. The total cutting amount is... Average finished pad area ≥ .

[0020] S22. For BGA pads located on the large copper surface after etching, a strategy to increase the solder mask opening is adopted. Specifically, for BGA pads located on the large copper surface after etching, the solder mask opening on the large copper surface is increased by 7.5% based on the original design, so that the area of ​​the etched pad is ≥ .

[0021] S23. For BGA pads that are connected to conductors or local copper surfaces after etching, an area compensation + cutting + solder mask window enlargement strategy is adopted. Among them, for BGA pads that are connected to conductors or local copper surfaces after etching, the cutting characteristics are classified as follows: S231. For inline pads without cutters, the overall BGA circuit layer is increased by 8% to 10%, and the corresponding BGA pad solder mask opening is increased by 5% on one side based on the original design, so that the average finished pad area after etching is ≥ ; S232. For pads on the line with single-sided clipping, where the BGA spacing is insufficient, the overall BGA pads on the circuit layer are increased by 10%, and then 42% to 9.2% of the pads are clipped on one side. Finally, the solder mask opening is increased by 5% to 15% on one side based on the original design, so that the average pad area after etching is ≥ ; S233. For the pads on the line where the BGA spacing is insufficient, increase the overall size of the BGA pads on the circuit layer by 10, then reduce the pad size by 42% to 9.2% on one side. Finally, increase the solder mask opening by 10%-20% on one side based on the original design, so that the average pad area after etching is ≥ Meanwhile, during this process, for the pads on both sides of the cut-out line, teardrops are added at the connection between the pad and the trace to enhance connection reliability when the trace width is ≤4mil.

[0022] S3. Determine the processing size based on the BGA pad size and execute the processing strategy in sequence. During the execution of the processing strategy, always follow the order of compensation first, then cutting, and finally increasing the solder mask opening. When the pad size is increased due to compensation, pre-compensation is performed with the original preset pad position as the center. During the cutting process, cutting control is performed based on the distance between the cutting position and the line to ensure that sufficient distance is maintained between the cutting position and the line after cutting. At the same time, the area after cutting is within the error range of the standard area. The distance between the cutting position and the center of the circle is calculated based on the area difference to ensure cutting accuracy. When increasing the solder mask opening, if the increased opening area does not overlap with the BGA circuitry, the opening is expanded outward from the original preset position. If there is overlap, the opening center position is adjusted to the side furthest from the overlap. S4. Measure and calculate the effective BGA pad area. Use a 4K digital microscope system to acquire pad images, and then import them into image analysis software for actual area analysis and calculation to determine the pass rate.

[0023] Working principle: This high-density, small-pitch BGA package board's refined pad processing method classifies the possible situations of pads on existing BGA package boards into three main types, including isolated BGA pads after etching, BGA pads located on large copper surfaces after etching, and BGA pads connected to conductors or local copper surfaces after etching. Different pre-etching pad processing schemes are adopted according to the three different types of BGA pads. For isolated BGA pads after etching, an area compensation + cutting strategy is adopted. During strategy execution, the isolated BGA pads are classified according to their original forming method. For those originally isolated BGA pads, the overall pad fabrication area is increased by 12% during the design phase. For those isolated BGA pads after cutting, indicating insufficient spacing between the original pad and the circuit, the overall pad fabrication area needs to be increased by 12%, followed by single-sided or double-sided cutting. The total cutting amount is... This ensures that the effective area of ​​the final isolated BGA pads is within the allowable error of ±20%, thus guaranteeing the effectiveness of the overall pads in subsequent soldering. For the BGA pads located on the large copper surface after etching, the solder mask openings on the large copper surface are increased by 7.5% on the basis of the original design, so that the area of ​​the etched pads is within the allowable error of ±20%, thereby achieving the expected effective area. For BGA pads that are connected to conductors or local copper surfaces after etching, they are classified according to cutting characteristics into three types: no cutting, single-sided cutting, and double-sided cutting. No cutting indicates that the entire BGA is connected to the circuit but there is no soldering interference. In this case, the overall size of the BGA on the circuit layer is increased by 8% to 10%, and the corresponding solder mask opening of the BGA pad is increased by 5% on one side based on the original design. For pads with single-sided cutting, where the BGA spacing is insufficient, the overall size of the BGA pad on the circuit layer is increased by 10%, and then 42% to 9.2% of the pad is cut on one side. Finally, the solder mask opening is increased by 5% to 15% on one side based on the original design. For pads with double-sided cutting, where the BGA spacing is insufficient, the overall size of the BGA pad on the circuit layer is increased by 10%, and then 42% to 9.2% of the pad is cut on one side. Finally, the solder mask opening is increased by -20% on one side based on the original design. This ensures that the final effective area of ​​the pad is within the allowable error of ±20%, so as to guarantee the effectiveness of the subsequent soldering of the overall pad. The entire solution involves listing all possible physical states of BGA pads and then implementing different compensation, cutting, and solder mask windowing strategies based on different physical states. Through systematic and comprehensive consideration, on the one hand, it ensures that the final formed pads will not damage or interfere with the original BGA circuitry; on the other hand, it maximizes the assurance that the final effective dimensions of various BGA pads after etching meet the error range, thereby reducing the reliability of subsequent soldering.

[0024] Furthermore, the entire solution provides corresponding compensation, cutting, and solder resist opening ratio operation data for different types. This data has been verified through extensive experiments. The following will describe it in detail with actual experimental data and examples. Example 1, such as Figure 4 As shown in the figure, this figure presents the experimental data analysis results of an original isolated BGA pad processing. In this experiment, a double-sided board with 18μm base copper was selected as the research object, and a BGA pad with a pitch of 0.5mm was designed. The pad size was 10mil, and the line width and line spacing of the BGA clamp were designed to be 3.0mil and the line spacing was designed to be 3.4mil. These were the basic experimental conditions. In this scheme, 2000 pads are selected as the statistical standard, and the compensation range of the pads is 0-2mil. 100 pads are configured in every 0.1mil span, and all 2000 pads are located on the same BGA circuit board. They are processed under the same etching conditions and then cleaned through a standardized process. The images of the pads are obtained by scanning under a 4K digital microscope. The images are then imported into ImageJ software, and the pad area is analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results are compared with the preset pad area to obtain the final area line chart of the 0-2mil compensation amount. The compensation amount shown in the figure is in the range of 0.8-1.2mil. Since the final effective area of ​​the 700 pads with compensation amounts below 0.8mil is less than 20% of the standard pad area, and the final effective area of ​​the 800 pads with compensation amounts above 1.2mil is higher than the minimum threshold of the standard pad area, the pad size is too large, which causes some points to interfere with the lines and poses a risk of short circuit in the future. Therefore, the statistical data of pads outside the range of 0.8-1.2mil are excluded. After statistical analysis, three effective points were selected: 0.8mil, 1.0mil, and 1.2mil. According to the statistical analysis, when the compensation amount reached 1.2mil, the effective area was closest to the standard area, and none of the points interfered with the lines. Then, through statistical calculation, the final compensation ratio was found to be 12%. Therefore, this experiment showed that for the original isolated BGA pads, a compensation amount of 12% ensures the maximum effective area and eliminates the risk of short circuits later.

[0025] Example 2, as follows Figure 6 As shown in the figure, this figure presents the experimental data analysis results of a BGA pad isolated after cutting. In this experiment, a double-sided board with 18μm base copper was also selected as the research object. A BGA pad with a pitch of 0.5mm was designed, with a pad size of 10mil. The line width and line spacing of the BGA clamping line were designed to be 3.0mil and the line spacing was designed to be 3.4mil, which served as the basic experimental conditions. In this scheme, 6000 pads were selected as the statistical standard, and three groups of 2000 pads were formed. The compensation amounts for the three groups were 0.8mil, 1.0mil, and 1.2mil, respectively. After compensation, the same cutting scheme was used for the three groups, with a cutting range of 0-1mil. 20 pads were allocated for every 0.01mil span as a step control. All 6000 pads were located on the same BGA circuit board and were processed under the same etching conditions. After processing, the images were obtained by scanning them under a 4K digital microscope after a standardized cleaning process. The images were then imported into ImageJ software, and the pad area was analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results were compared with the preset pad area to obtain the final area line chart of the 0-1mil cutting amount. The diagram shows the range of 0.42-0.92 mil. The 820 pads with a cutting depth below 0.42 mil had excessively large pad sizes, causing interference between some points and the circuitry, posing a risk of short circuits later. Additionally, the 160 pads with a cutting depth above 0.92 mil had a final effective area less than 20% of the standard pad area. Therefore, the statistical data for pads outside the 0.42-0.92 mil range were excluded. After statistical analysis, three effective points were selected: 0.42mil, 0.67mil, and 0.92mil. According to the statistical analysis, with a compensation amount of 1.2mil, the effective area is closest to the standard area when the cutting amount reaches 0.42mil. At the same time, none of the points interfere with the circuit. Then, the final cutting ratio was obtained through statistical calculation as 9.2%. Therefore, this experiment shows that for isolated BGA pads after cutting, a compensation amount of 12% and a cutting ratio of 4.2% can ensure the maximum effective area and eliminate the risk of short circuits later.

[0026] Example 3, as follows Figure 7 As shown in the figure, this figure presents the experimental data analysis results of BGA pad processing on a large copper surface. In this experiment, a double-sided board with 18μm base copper was also selected as the research object. A BGA pad with a pitch of 0.5mm was designed, with a pad size of 10mil. The line width and line spacing of the BGA clamp were designed to be 3.0mil and the line spacing was designed to be 3.4mil, which served as the basic experimental conditions. In this scheme, 3000 pads are selected as the statistical standard, and the solder mask opening increment of the pads is 0-3mil. 100 flip points are allocated for every 0.1mil span, and the 3000 pads are located on the same BGA circuit board. They are processed under the same etching conditions. After processing, they are cleaned through a standardized process and then the images of the pads are obtained by scanning under a 4K digital microscope. The images are then imported into ImageJ software, and the pad area is analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results are compared with the preset pad area to obtain the final area line chart of the 0-3mil solder mask opening range. The diagram illustrates an increment range of 0.5-2.0 mil. For the 400 pads with window sizes less than 0.5 mil increments, the small window size results in all exposed pad areas being smaller than the minimum allowable error range for the standard area. For the 1000 pads with window sizes greater than 2.0 mil increments, some pads within each pad's span interfere with the circuitry, and the number of interfering pads increases with the area, posing a risk of short circuits later. Therefore, the statistical data for pads outside the 0.5-2.0 mil window increment range were excluded. After statistical analysis, five effective points were selected with increments of 0.5mil, 0.75mil, 1.0mil, 1.5mil, and 2.0mil. Statistical analysis showed that when the solder mask opening size increment was 0.75mil, the effective area was closest to the standard area, with an average area reaching 101.78% of the standard area. At the same time, none of the points interfered with the circuit. Then, through statistical calculation, the final solder mask opening ratio was found to be 7.5%. Therefore, this experiment showed that for BGA pads located on large copper surfaces, an increment ratio of 7.5% for the solder mask opening ensures the maximum effective area and eliminates the risk of short circuits later.

[0027] Example 4, as follows Figure 8 As shown in the figure, this figure presents the experimental data analysis results of an isolated BGA pad connected to a conductor or local copper surface after etching. In this experiment, a double-sided board with 18μm base copper was also selected as the research object. A BGA pad with a pitch of 0.5mm was designed, with a pad size of 10mil. The line width and line spacing of the BGA clamping line were designed to be 3.0mil and the line spacing was designed to be 3.4mil, which served as the basic experimental conditions. In this scheme, 9000 pads were selected as the statistical standard, and three groups of 3000 pads were formed. The compensation amounts for the three groups were 0.8mil, 1.0mil, and 1.2mil, respectively. After compensation, the same solder mask window increment scheme was adopted for the three groups, and the solder mask window increment range of the pads was 0-3mil. 100 flip points were allocated for every 0.1mil span, and the 9000 pads were located on the same BGA circuit board. They were processed under the same etching conditions. After processing, they went through a standardized cleaning process and then the images of the pads were obtained by scanning under a 4K digital microscope. The images were then imported into ImageJ software, and the pad area was analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results were compared with the preset pad area to obtain the final area line graphs of the three groups of pads with compensation amounts of 0.8mil, 1.0mil, and 1.2mil in the 0-3mil solder mask window range. The diagram illustrates an increment range of 0.5-2.0 mil. For the 1200 pads with window sizes less than 0.5 mil increments, the small window size results in all exposed pad areas being smaller than the minimum allowable error range for the standard area. For the 3000 pads with window sizes greater than 2.0 mil increments, some pads within each pad's span interfere with the circuitry, and the number of interfering pads increases with the area, posing a risk of short circuits later. Therefore, the statistical data for pads outside the 0.5-2.0 mil window increment range were excluded. After statistical analysis, five effective points were selected with increments of 0.5mil, 0.75mil, 1.0mil, 1.5mil, and 2.0mil. The analysis showed that when the solder mask window size increment was 0.8mil, the control group with a compensation of 1.2mil had an excessively large effective area. However, all points with compensation within the range of 0.8-1.0mil met the standard within the window increment range of 0.5-2.0mil. Furthermore, the effective area was closest to the standard area when the solder mask window increment was 0.5mil, with the 0.8mil compensation showing the best results. The average effective area is 104.65% of the standard area; while the average effective area of ​​1.0mil compensation is 104.0% of the standard area. At the same time, there is no interference with the line at any point. Then, through statistical calculation, the final reasonable compensation amount is 8%-10%, and the solder mask opening increment ratio is 5%. Therefore, through this experiment, it was found that for isolated BGA pads that are connected to conductors or local copper surfaces after etching, when the pad compensation amount is 8%-10% and the solder mask opening increment ratio is 5%, the maximum effective area is guaranteed and there is no risk of short circuit in the later stage.

[0028] Example 5, as Figure 9As shown in the figure, this figure presents the experimental data analysis results of a pad on a line that is connected to a conductor or a local copper surface after etching and is shaped on one side. In this experiment, a double-sided board with 18μm base copper was also selected as the research object. A BGA pad with a pitch of 0.5mm was designed, with a pad size of 10mil. The line width and line spacing of the BGA clamping line were designed to be 3.0mil and the line spacing was designed to be 3.4mil, which served as the basic experimental conditions. In this scheme, 8000 solder pads are selected as the statistical standard, and all pads are treated with a uniform compensation amount of 1.0 mil. The pads are then divided into four groups of 2000 each, with solder mask window increments of 0.5 mil, 1.0 mil, 1.5 mil, and 2.0 mil for the four groups, respectively. Before solder mask windowing, all four groups use the same cutting scheme, and the pad cutting span ranges from 0 to 1 mil. Each 0.1 mil span is allocated to 20 solder pads, and all 8000 solder pads are in the same... On a BGA circuit board, the same etching conditions are used for processing. After processing, the board undergoes a standardized cleaning process. The images of the pads are then scanned under a 4K digital microscope to obtain the images. The images are then imported into ImageJ software, and the pad area is analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results are compared with the preset pad area to obtain the final area line graphs of four groups of pads with solder mask opening increments of 0.5mil, 1.0mil, 1.5mil and 2.0mil in the 0-1mil cutting range. The diagram shows the cutting range of 0.42-0.92 mil. For the 860 pads with a cutting size below 0.42 mil, the excessively small cutting size caused interference between some pads and the traces within each pad's span. Conversely, for the 160 pads with a cutting size above 0.92 mil, some pad areas were smaller than the maximum allowable error range for the standard area. Therefore, the statistical data for pads outside the 0.42-0.92 mil cutting size range were excluded. After statistical analysis, three effective points were selected with cutting amounts of 0.42mil, 0.67mil, and 0.92mil. Based on the statistical analysis, with a compensation amount of 1.0mil, all points with solder mask opening sizes in the range of 0.5mil-1.5mil and cutting amounts in the range of 0.42mil-0.92mil met the requirements. Therefore, this experiment showed that for online pads that are connected to conductors or local copper surfaces after etching and are cut on one side, with a compensation amount of 10%, a cutting amount of 4.2%-9.2%, and a solder mask opening increment of 5%-15%, the maximum effective area can be guaranteed without the risk of short circuits later.

[0029] Example 6, as Figure 10As shown in the figure, this figure presents the experimental data analysis results of a wire pad that is connected to the conductor or local copper surface after etching and has a double-sided shaving. In this experiment, a double-sided board with 18μm base copper was also selected as the research object. A BGA pad with a pitch of 0.5mm was designed, with a pad size of 10mil. The line width and line spacing of the BGA clamping line were designed to be 3.0mil and the line spacing was designed to be 3.4mil. These were the basic experimental conditions. In this scheme, 8000 solder pads are selected as the statistical standard, and all pads are treated with a uniform compensation amount of 1.0 mil. The pads are then divided into four groups of 2000 each, with solder mask window increments of 0.5 mil, 1.0 mil, 1.5 mil, and 2.0 mil for the four groups, respectively. Before solder mask windowing, all four groups use the same cutting scheme, and the pad cutting span ranges from 0 to 1 mil. Each 0.1 mil span is allocated to 20 solder pads, and all 8000 solder pads are in the same... On a BGA circuit board, the same etching conditions are used for processing. After processing, the board undergoes a standardized cleaning process. The images of the pads are then scanned under a 4K digital microscope to obtain the images. The images are then imported into ImageJ software, and the pad area is analyzed and calculated in a professional-grade imaging analysis environment. The final calculation results are compared with the preset pad area to obtain the final area line graphs of four groups of pads with solder mask opening increments of 0.5mil, 1.0mil, 1.5mil and 2.0mil in the 0-1mil cutting range. The diagram shows the cutting range of 0.42-0.92 mil. For the 860 pads with a cutting size below 0.42 mil, the excessively small cutting size caused interference between some pads and the traces within each pad's span. Conversely, for the 160 pads with a cutting size above 0.92 mil, some pad areas were smaller than the maximum allowable error range for the standard area. Therefore, the statistical data for pads outside the 0.42-0.92 mil cutting size range were excluded. After statistical analysis, three effective cutting depths of 0.42mil, 0.67mil, and 0.92mil were selected. Based on the statistical analysis, with a compensation of 1.0mil, all locations with solder mask opening sizes between 0.5mil and 2.0mil and cutting depths between 0.42mil and 0.92mil met the requirements. Furthermore, with a compensation of 1.0mil, the optimal effective area was achieved when the solder mask opening size was between 0.5mil and 2.0mil, the compensation was 10%, the cutting depth was between 4.2% and 9.2%, and the solder mask opening increment was 20%, with no risk of subsequent short circuits.

[0030] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for refined pad processing of a high-density, small-pitch BGA package board, characterized in that, Includes the following steps: S1. Obtain BGA pad images and determine the BGA pad type based on the BGA pad images; S2. Based on the concept of effective constant control of BGA pad area, differentiated BGA pad collaborative processing strategies are designed for different BGA pad types, including area compensation pre-increase, area cutting and solder mask opening enlargement. S3. Determine the processing dimensions based on the BGA pad dimensions and execute the processing strategy in sequence; S4. Measure and calculate the effective BGA pad area and confirm that it is qualified.

2. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 1, characterized in that, In step S1, based on the final shape of the pads after etching and the solder mask coverage, BGA pads are classified into three core types: isolated BGA pads after etching, BGA pads located on large copper surfaces after etching, and BGA pads connected to conductors or local copper surfaces after etching.

3. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 2, characterized in that, In step S2, different processing strategies are implemented for different types of circuit patterns and solder mask patterns to optimize the final effective BGA pad area. ,in For the area after processing, To design the standard area.

4. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 3, characterized in that, In step S2, the detailed execution strategy includes: S21. For isolated BGA pads after etching, an area compensation + cutting strategy is adopted. S22. For BGA pads located on the large copper surface after etching, a strategy of increasing the solder mask opening is adopted. S23. For BGA pads that are connected to conductors or local copper surfaces after etching, adopt the strategy of area compensation + cutting + increasing solder mask opening.

5. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 4, characterized in that, In step S21, isolated BGA pads are classified according to their forming method, including: S211, Original Isolated BGA Pads: For pads that are initially isolated, the overall fabrication area of ​​the pad is increased by 12% during processing, so that the area of ​​the pad after etching is ≥ ; S212. After cutting, the BGA pads become isolated. For these pads with insufficient spacing, the overall fabrication area of ​​the pads is increased by 12%, and then cut on one or both sides. The total cutting amount is... Average finished pad area ≥ .

6. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 4, characterized in that, In step S22, for the BGA pads located on the large copper surface after etching, the solder mask openings on the large copper surface are increased by 7.5% overall based on the original design, so that the area of ​​the etched pads is ≥ .

7. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 4, characterized in that, In step S23, BGA pads that are connected to wires or local copper surfaces after etching are classified according to cutting characteristics, including: S231. For inline pads without cutters, the overall BGA circuit layer is increased by 8% to 10%, and the corresponding BGA pad solder mask opening is increased by 5% on one side based on the original design, so that the average finished pad area after etching is ≥ ; S232. For pads on the line with single-sided clipping, where the BGA spacing is insufficient, the overall BGA pads on the circuit layer are increased by 10%, and then 42% to 9.2% of the pads are clipped on one side. Finally, the solder mask opening is increased by 5% to 15% on one side based on the original design, so that the average pad area after etching is ≥ ; S233. For the pads on the line where the BGA spacing is insufficient, increase the overall size of the BGA pads on the circuit layer by 10%, then reduce the pad size by 42% to 9.2% on one side. Finally, increase the solder mask opening by 10%-20% on one side based on the original design, so that the average pad area after etching is ≥ .

8. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 7, characterized in that, For pads on both sides of the line with a cut-out design, teardrops are added at the connection between the pad and the trace to enhance connection reliability when the trace width is ≤4mil.

9. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 1, characterized in that, In step S3, during the execution of the processing strategy, the order of compensation first, cutting then increasing the solder mask opening is always followed. When the pad size is increased, pre-compensation is performed with the original preset pad position as the center. During the cutting process, cutting control is performed based on the distance between the cutting position and the line to ensure that sufficient distance is maintained between the cutting position and the line after cutting. At the same time, the area after cutting is within the error range of the standard area. The distance between the cutting position and the center of the circle is calculated based on the area difference to ensure cutting accuracy. When the solder mask opening is increased, if the increased opening area does not overlap with the BGA line, the opening is expanded outward from the original preset opening position as the center; if there is overlap, the opening center position is adjusted to the side away from the overlap.

10. The method for refined pad processing of a high-density, small-pitch BGA package board according to claim 1, characterized in that, In step S4, a 4K digital microscope system is used to acquire images of the solder pads, which are then imported into image analysis software for actual area analysis and calculation to verify the pass rate.

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