JP2007147591A - Analytical method for recess or protrusion in micropore after filled with copper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To disclose an analytical method for a recess or a protrusion in a micropore (micro via or laser via) after filled with copper. <P>SOLUTION: A height distribution of a copper plated layer generated on a layered material surface after executing a step for filling the copper in a printed circuit board is measured using a height scanner, and a plurality of height values is selected thereafter in a copper coated area in a local part of a located portion of the each micropore. The plurality of numbers of height values in the periphery of the micropore in the copper coated area in the local part is averaged or calculated to obtain a relative standard height, and the relative standard height is compared with the each height value of a copper coated surface within a micropore range to find a difference therebetween. Calculation is executed whether an accumulated quantity of the respective differences exceeding an allowable recess amount or an allowable protrusion amount exceeds a set value or not. The presence of a recess or protrusion defect on the the copper coated surface within the micropore range is determined when exceeding the set value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for analyzing dents or protrusions after filling micropores with copper. This is a method of analyzing whether or not there is a dent or protrusion defect on the surface after filling the microholes on the printed circuit board with copper.

  Driven by the needs of electronic products, printed circuit boards are becoming lighter, thinner, shorter, and smaller in form and are required to have stable performance, multiple functions, and high speed in terms of function. In comparison, the technological development of the manufacturing process has become increasingly difficult, and needs for high-density designs such as lighter, thinner, thinner, and smaller holes must be satisfied. Ball grid array (BGA) and flip chip substrates, which are very important now, and circuit boards of portable products whose usage is increasing day by day, for example, central processing of mobile phones and computers Devices, electronic dictionaries, PCMCIA cards, etc. will eventually use a large amount of High Density Integration (HDI) boards. Although conventional substrates are continually improved in production facilities such as drilling machines and etching devices, due to the lack of density, only up to 4 mil line distance and 6 mil diameter through holes can be produced. Therefore, it cannot cope with the above-mentioned needs and restrictions on electronic structure design with a narrow pin distance in the future. Therefore, a high-density substrate having fine wires and small holes has emerged with time, and is expected to replace the conventional manufacturing process of multilayer crimped substrates and printed circuit boards.

  On the other hand, the build-up method can effectively reduce the use area of the through hole by combining laser drilling technology with the substrate manufacturing process, and easily meet the high density requirements of fine wires and small holes. Can be satisfied. Thus, if one or several thin wire layers are added to the conventional substrate structure, an economical and effective substrate manufacturing method is obtained. The intermediate layer of such a substrate may be a conventional FR-4 or ABF substrate, and after each layer is added, a dielectric layer and copper foil are added, and these superimposed lines and hole diameters are all finer than the conventional substrate, Also, the thickness between layers is relatively reduced. Since the density is thus increased and the thickness is reduced, the area of the substrate is also reduced.

  However, in the multi-layer method, the defect most frequently generated after the step of filling the substrate with copper is a recess 141 (or protrusion, not shown) in the copper plating layer 14 above the microhole 15 as shown in FIG. Is likely to occur. A microhole 15 is provided in the upper insulating layer 11, and a copper pad (pad) 12 of an internal copper circuit layer is provided at the bottom of the microhole 15. In order to connect the copper pad 12 and the copper line layer formed on the surface of the upper insulating layer 11 thereafter, a copper plating layer 14 is deposited in the micro holes 15 and on the surface of the upper insulating layer 11. However, if there is a dent 141 (or protrusion) defect in the copper covered area above the micropore 15, when the pit 141 is large when attempting to continue the lamination on the copper plating layer 14, the internal line of the substrate It becomes invalid and the electric signal cannot be transmitted normally.

  To sum up the above, in the market, there is an urgent need to analyze whether there is a dent defect on the surface after copper plating of micro holes on the printed circuit board so that the quality of each laminated board in the printed circuit board can be confirmed. It is necessary.

  An object of the present invention is to provide a method for analyzing dents or protrusions after filling micropores with copper. This method can remove the influence of the deformation amount of the laminated board material of the printed circuit board, and analyze the actual depth and effective area of the copper plating layer above each blind hole.

  Another object of the present invention is to provide a method for representing the distribution of dents or raised defects on a copper plating layer. In this method, the revocation result of the printed circuit board cell caused by such a dent defect is further displayed by displaying the location of the dent or convex defect on the screen.

  In order to achieve the above object, the present invention discloses a method of analyzing a dent or protrusion after filling micropores with copper. This is done by measuring the height distribution of the copper plating layer formed on the surface of the laminated material after performing the step of filling the printed circuit board with copper using a height scanning device, and then localizing the location of each micropore (or Select multiple height values for copper coverage area around micropores. A plurality of height values around the micropores of the local copper coating area are averaged to obtain a relative standard height, and each of the relative standard height and the copper coating surface within the micropore range Compare the height values and give each difference value. It is calculated whether or not the cumulative amount exceeding the allowable dent amount or allowable bulge amount of each difference value exceeds the set value. If it exceeds, it can be determined that there is a dent or raised defect on the surface of the copper coating within the micropore range.

  The presence location of the dent defect on the printed circuit board can be displayed using the screen or chart, and the printed circuit board cell position where the dent defect has caused the invalidation can be expressed using the screen or chart.

  FIG. 2 is an external explanatory view of a laminated board material in a printed circuit board analyzed by the present invention. The laminated board 20 is divided into nine cells 26, each of which has a plurality of micro holes 25, and the micro holes 25 and the entire surface of the laminated board 20 are covered with the copper plating layer 24. Yes. After measuring the height distribution on the surface of the copper plating layer 24 using a height scanning device, the copper coating area 271 or 272 larger than the cross-sectional area of each micropore 25, particularly for the location of each micropore 25. Is selected. Alternatively, the selected area can also be referred to as a range of interest. In order to include the designated micropore 25 in the copper-covered area 271 or 272, the copper-covered area 271 or 272 may be formed with a size obtained by adding an allowable width to the actual micropore size.

  Referring to FIG. 3, all the height distribution values of the surface within the selected copper covering area 271 have already been obtained, and each of the local height distribution values is analyzed, and the dent 32 exceeding the allowable standard is obtained. It is possible to determine whether or not (or protrusion) has occurred. A broken-line cylindrical body 31 in the drawing indicates a positional relationship with respect to the lower microhole 25 of the recess 32, and the radius of the cross section of the microhole 25 is r. Obviously, the height of the curved surface of the upper center recess 32 of the cylinder 31 is lower than the surface height around the cylinder 31 (if the center is protruding, it becomes higher than the surface height around the cylinder 31).

  FIG. 4A is a height distribution diagram along the XY plane passing through the diameter of the cylindrical body 31 in FIG. Since the laminated plate member 20 may cause a jumping phenomenon due to residual stress in the material, the height value shown on the Z axis is not necessarily the height of the actual dent or protrusion on the surface of the laminated plate member 20. Therefore, a significant amount of dents or protrusions can be defined only after the standard height or reference height is first obtained. In the present invention, the relative standard height R is obtained by averaging or calculating the height distribution value around the micropores 25 (outside 2r in FIG. 4A) of the copper-covered area 271, and each micropore 25 is further calculated. Calculate the relative standard height for each.

  Taking the dent situation as an example (the reverse projection situation is also true), the height threshold T can be defined by shifting below the relative standard height R by the allowable dent amount h, and the height value is T If it is lower than the surface of the surface, it is regarded as an effective dent region. In FIG. 4A, d is determined as an effective dent region.

  As shown in FIG. 4B, even if it is determined that the copper-covered area 271 has an effective dent region, it is not necessarily regarded as a dent defect. In general, it is necessary to further calculate the area occupied by the effective dent region, and only then can it be confirmed whether or not the dent defect is truly a defect. For example, there is a fine needle hole 41 in the copper covered area 271, and the minimum height of this needle hole 41 is clearly much smaller than the height threshold T. However, if the ratio to the total area of the bottom of the needle hole 41 is not analyzed and only the comparison with the height threshold T is made, there is a great possibility that the dent defect is recognized too much and the result is inappropriate. If there are too many cells 26 that are determined to be defective, a significant cost burden is caused. In fact, if there is only a fine needle hole 41 in the copper-covered area 271 and the heights of all other areas are higher than the height threshold T, the normal function of the vertical conduction function is impaired by this needle hole 41. Is unlikely. In addition, the allowable area of the needle hole 41 can be set by the user.

  As shown in FIG. 5, the area included in the cross-sectional area of the micropore 25 (the area of a circle having a diameter of 2r) can be divided into a plurality of area basic cells 51 according to the position of the height value measurement point. All area basic cells 51 have at least one height value. By comparing the relative standard height R with the height value of each area basic cell 51, the value of each difference is obtained. For example, the numbers shown in FIG. 5 represent the difference values (or the size of the difference values are expressed by colors or symbols so that the user can easily read them). If the difference value is larger than the allowable dent amount h (assuming that h = 4 in this embodiment) and the area is larger than the set value, it is considered that there is a dent defect. In other words, if the cumulative quantity with the difference value exceeding 4 (the total of 7 numbers in FIG. 5 exceeds 4) exceeds the set value (assumed to be 5), the copper covered area 271 has an effective dent (dent defect). ).

  After performing the above-described height analysis on the copper coating area selected at each microhole 25 location on the laminated board 20, the position of the copper-filled microhole 25 having a dent defect can be displayed using a screen or a chart. . For example, FIG. 6 shows a dent defect location with a symbol x or a mark. Of course, you may display with a color instead of x. For example, when the micropore 25 having a dent defect is displayed in red (or the micropore 25 having a protruding defect is filled in blue), the other normal micropores 25 are represented in green. Of course, the size of the indentation may be represented by different colors, symbols, or marks. For example, dark red represents a portion where the dent amount is relatively deepest, dark red gradually changes to light red, and a dent amount relatively small represents yellow.

  After each laminated board 20 is sequentially laminated and becomes a final substrate, if there is a dent defect in the laminated board 20 of a certain layer in it, the printed circuit board cell having the dent defect is discarded. Is considered. Therefore, as shown in FIG. 7, statistics are obtained as to whether or not there is a dent or protrusion defect in each printed circuit board cell 76, and if there is a dent or protrusion defect, it is used with a symbol or mark x. A printed circuit board cell 76 that can be disabled or discarded can be represented.

  In addition to being able to analyze the quality of the copper plating layer 24 before etching, the present invention can also analyze whether or not the copper plating layer 84 after etching has a dent defect as shown in FIG. Since there is a copper plating layer 84 after etching in the selection range 87 set at a position with the micro holes 85 on the laminated plate member 80, the surface height of the outer side of the copper plating layer 84 is recessed as shown in FIG. Much lower than possible height. However, the step different from the above embodiment is only the calculation method of the relative standard height R. In the present embodiment, the copper coated area in the selection range 87 is averaged with the height distribution value in the annular region between 2r and 2Rc to obtain the relative standard height R '. That is, a section in which the height on both sides is much lower than the minimum threshold value L is not included in the average data of the relative standard height. Similarly, whether or not the effective dent area of the copper plating layer 84 exists within the selected range can be confirmed by the height threshold T ′. If the effective dent area exceeds the set value, the dent defect is not formed in the microhole 85. It can be determined that there is.

  Although the technical contents and technical features of the present invention are as disclosed above, those skilled in the art will make various substitutions and modifications based on the teaching and disclosure of the present invention without departing from the spirit of the present invention. Can do. Accordingly, the protection scope of the present invention should not be limited to that disclosed in the examples, but includes various substitutions and modifications that do not depart from the present invention and are intended to be encompassed by the claims.

The figure which shows the dent generation | occurrence | production of the laminated board material in a well-known multilayering method board The figure which shows the external appearance of the laminated board material in the printed circuit board analyzed by this invention Fig. 2 Three-dimensional height distribution map for selecting the copper coating area Height distribution diagram cut along the XY plane passing through the micropore diameter in FIG. Height distribution diagram cut along the XY plane along the diameter of micro-holes after filling copper with needle holes The figure which shows the analysis of the effective dent area in the range containing the micropore cross-sectional area of the copper plating layer of this invention The figure which shows the micropore position with the dent defect of this invention The figure which shows the printed circuit board cell which became unusable by the dent defect of this invention The figure which shows another Example which sets the selection range on a copper plating layer Height distribution diagram cut along XY plane passing through micropore diameter in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Upper insulating layer 12 Copper pad 13 Lower insulating layer 14 Copper plating layer 15 Blind hole 20 Laminated plate material 24 Copper plated layer 25 Micro hole 26 Cell 31 Cylindrical body 32 Recess 41 Needle hole 51 Area basic cell 76 Printed circuit board cell 80 Laminated plate material 84 Copper plating layer 85 Micropore 87 Selection range 141 Depression 271 272 Copper coating area T, T 'Height threshold r Blind hole radius d Effective dent area R, R' Relative standard height h Allowable dent amount

Claims (8)

A method of analyzing a dent in a copper-filled micropore,
Scanning the height distribution on the surface of the laminated board after the copper filling step is performed;
Selecting a plurality of height values of the local copper coating area of at least one microporous location in the laminate sheet;
Calculating a plurality of height values where the local copper coating area is outside the micropore range to obtain a relative standard height; and
Comparing each difference value present between the relative standard height and each of the plurality of height values of the copper coverage within the micropore range;
A step of calculating a cumulative quantity in which the value of each difference exceeds an allowable dent amount, and a step of determining that there is a dent defect in the copper covered area on the microhole if the cumulative quantity exceeds a set value. A method for analyzing a dent in a copper-filled micropore, comprising:   The method for analyzing a dent in a copper-filled microhole according to claim 1, further comprising a step of representing the dent defect occurrence location with a symbol, a mark, or a color on the image of the laminated board.   The recess of a copper-filled microhole according to claim 1, further comprising a step of representing, as a symbol, a mark, or a color, a waste cell due to the presence of the recess defect on an image of a printed circuit board having the laminated board. Analysis method.   The value of each difference can be represented by a number, a color, or a symbol, and the position of each difference value within a range included in the micropore cross-sectional area is displayed. Item 2. A method for analyzing a recess of a copper-filled micropore according to Item 1.   When the allowable dent amount is subtracted from the relative standard height, it becomes a height threshold, and when the cumulative quantity exceeds the set value, the area is lower than the height threshold within the range included in the micropore cross-sectional area. 2. The method for analyzing a dent in a copper-filled micropore according to claim 1, wherein the dent defect exceeds a defined allowable dent area.   The method for analyzing a dent in a copper-filled microhole according to claim 1, wherein the copper coating area on the laminated plate material has undergone an etching step.   7. The method of claim 6, further comprising the step of removing the height value of the portion of the non-copper-covered area by a minimum threshold value and not including in the calculation for obtaining the relative standard height. Hole indentation analysis method.   The recess of a copper-filled microhole according to claim 1, wherein the relative standard height is obtained by averaging a plurality of height values outside the micropore range of the local copper coating area. Analysis method.

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