KR100833382B1 - Analysis method for sag or protrusion of copper-filled micro via - Google Patents

Abstract

The present invention is a method for analyzing depressions or protrusions that occur after a type of micro via or via is performed in a copper filling step. Survey the altitude distribution of the copper plating layer and then select a plurality of altitude values within the local copper cladding area of the area where each microvia is located. The local copper cladding area averages or calculates a plurality of altitudes around the microvia to obtain a relative reference altitude, and determines the difference value by comparing each relative value of the copper cladding surface within the microvia range with the relative reference altitude. . It may be calculated whether the cumulative quantity of the difference value larger than the allowable depression or allowable protrusion amount exceeds the predetermined value, and if the predetermined value is exceeded, the copper cladding surface within the microvia range may be determined to have a depression or protrusion defect.

Printed circuit board, microvia, depression, protrusion, copper plating layer, difference value

Description

ANALYSIS METHOD FOR SAG OR PROTRUSION OF COPPER-FILLED MICRO VIA

1 is a diagram showing a depression occurred in a laminated board of a conventional build-up method substrate.

Figure 2 is an appearance of the laminated plate of the printed circuit board analyzed by the present invention.

3 is a three-dimensional altitude distribution diagram within the copper covering area selected in FIG.

Figure 4 (a) is an elevation distribution obtained through the X-Y plane of the diameter of the micro via (micro via or laser via) in FIG.

Figure 4 (b) is the elevation distribution of the X-Y plane of the diameter of the microvia after copper filling with invasion.

Figure 5 is a schematic of an analysis of the effective depression area within the coverage range of the microvia with copper plating layer according to the present invention.

6 is a schematic representation showing locations of recessed defect microvias in accordance with the present invention.

7 is a view showing an unusable printed circuit board cell formed due to a depression defect in accordance with the present invention.

8 is a view showing another embodiment for setting a selection range of a copper plating layer.

FIG. 9 is a high degree distribution diagram of the X-Y plane of the diameter of the microvia in FIG. 8; FIG.

* Explanation of symbols for the main parts of the drawings

11: top layer insulating layer 12: copper pad

13: lower layer insulating layer 14: copper plating layer

15: microvia ( blind via but according to the text) 20: laminated sheet

24: copper plating layer 25: micromicrovia

26: Wexel 32: Weak

41: Invasion 51: Area base cell

76: printed circuit board cell

80: laminated sheet material 84: copper plating layer

85: 크로 Microvia 87: Selection range

141: dent 271, 272: copper covering area

T 、 T ': Altitude threshold r: Radius of microvia

d: Effective depression area R, R ': Relative reference altitude

h: permissible depression

The present invention is a kind of analysis method for depressions or protrusions occurring after the micro vias or the laser vias have been subjected to the copper filling step. The present invention relates to the presence of depressions or protrusion defects on the surface after copper is filled in the microvias on the printed circuit board. How to analyze.

Printed circuit boards are getting lighter and smaller due to the demands of electronic products, but they require stable performance, multifunction, and high speed in terms of function. Relatively, however, the development of manufacturing technology is becoming more and more difficult to meet the demands of high density design such as light, thin, thin, and small holes. Today's popular ball grid array (BGA) or flip chip substrates and rapidly growing circuit boards in portable products such as mobile phones, computer central processing units, electronic dictionaries and PCMCIA cards High Density Integration (HDI) substrates will be used. In order to overcome the disadvantage of the low density of the existing substrate, in terms of manufacturing, the renovation of the manufacturing equipment such as perforator, etching machine, etc. was constantly renovated, but the requirements of the above-mentioned via hole is 4 millimeters (mil) and 6 millimeters in diameter. And the limitations of future electronic structural design. This trend has resulted in high-density substrates with thin lines and small holes, and is expected to replace the manufacturing process of conventional multilayer substrates or printed circuit boards.

The combination of laser drilling in a relatively build-up substrate manufacturing process will effectively reduce the spot area of the via holes, making it easier to achieve high density thinner and smaller holes requirements. The technique is to increase one layer or multiple layers of filaments in a traditional substrate structure, which is an economical and effective method of manufacturing a substrate. In this type of substrate, the interlayer is possible for both traditional FR-4 or ABF substrates. Next, the upper dielectric layer and the copper foil are superposed on each layer in order. Both the overlapping lines and hole diameters are smaller than traditional substrates, and the interlayer thicknesses are also relatively reduced, resulting in increased density and thinner thickness, resulting in a smaller substrate area.

The most obvious disadvantage of the substrate produced by the deposition method is that after the copper filling step, the depression 141 (or projections, not shown) often occurs in the copper plating layer 14 located on the microvia 15. As shown in FIG. The upper insulating layer 11 has a microvia 15, and a copper pad 12 of an inner copper line layer is provided at the bottom of the microvia 15. A copper plating layer 14 is provided on the inside of the microvia 15 and the surface of the upper insulating layer 11 to connect the copper wire layer 12 and the copper wire layer formed next to the surface of the upper insulating layer 11. I deposit it. However, in the case where the depression 141 (or protrusion) defect occurs in the copper covering area on the upper side of the microvia 15, the copper plating layer 14 is continuously stacked so that the depression 141 becomes serious. The function of the line is lost and electric signals cannot be transmitted normally.

In summary, it is urgently necessary to analyze whether the surface of the microvia of the printed circuit board after the copper plating is a defect or not, in this way it is possible to determine the quality of the laminated plate of the printed circuit board.

It is an object of the present invention to eliminate the effect of the deformation of the laminated sheet of a printed circuit board, and a type of microvia capable of analyzing the actual depth of depression and the effective area of the copper plating layer on each microvia is a depression generated after the copper filling step. Or to provide an analysis method for the projection phenomenon.

Still another object of the present invention is to display the site where the depression or protrusion defects are present and to display the result of the loss of the function of the cell of the printed circuit board due to the depression so that the depression or protrusion defect of the copper plating layer is improved. To provide a way to present the distribution.

In order to achieve the above object, the present invention provides an analysis method for the depression or protrusion phenomenon appearing after the microvia is subjected to the copper filling process. An altitude scan device was used to measure the altitude distribution of the copper plating layer on the surface of the laminated sheet after the copper filling step of the printed circuit board, and then a plurality of copper within the area (or around the microvia) where the respective holes are located. Select the altitude value. A plurality of altitude values around the microvia are set as relative reference altitudes, and respective difference values are calculated by comparing the relative reference altitudes with each altitude value of the copper-coated surface within the microvia range. Calculate whether or not each difference exceeds the expected value of the cumulative quantity greater than the allowable depression or the allowable protrusion, and if it exceeds the determined value, determine that there is a depression or protrusion defect on the copper clad surface within the microvia range.

The position where the recessed defects exist on the printed circuit board may be displayed on a screen or a diagram, and the position of the printed circuit board cells whose functions are lost due to the recessed defects may also be displayed on a screen or a diagram.

(Example)

Figure 2 is a view showing the appearance of the laminated plate of the printed circuit board analyzed by the present invention. The laminated sheet 20 is divided into nine cells 26, and a plurality of microvias 25 are included in one cell 26. One copper plating layer 24 is coated on both the microvia 25 and the entire laminated sheet 20 surface. An altitude scanning device can be used to survey the surface altitude distribution of the copper plating layer 24, in particular the copper covering area greater than the cross-sectional area of the microvia 25 for each position where each microvia 25 is present ( 271 or 272) may be selected one by one, or the selected area may be referred to as a selection range. One allowable area is added based on the actual microvia size to form the copper coverage area 271 or 272 so that the copper coverage area 271 or 272 includes the designated microvia 25.

Referring to Fig. 3, since all surface altitude distribution values in the already selected copper cover area 271 have already been acquired, the analysis of the corresponding local altitude distribution values is performed respectively, so that the depressions 32 (protrusions) exceeding the allowable standard are Determine if it occurred. The circumferential body 31 indicated by a dotted line in the drawing indicates the relative positional relationship between the depression 32 and the lower microvia 25, and the radius of the cross section of the microvia 25 is r. It was clearly shown that the altitude of the curved surface 32 of the upper center of the columnar body 31 was lower than the surface altitude of the periphery of the cylinder body 31. (If center is higher than surface around circumference 31).

Figure 4 (a) is a high degree of distribution obtained through the X-Y plane of the diameter of the cylinder 31 in FIG. Since the laminated sheet 20 is warp due to the residual stress in the material, the altitude value indicated on the Z axis is not the altitude at which the surface of the laminated sheet 20 is actually recessed or raised. Therefore, the relative reference altitude or reference altitude must first be found to define the actual depression or elevation. In the present invention, the relative reference altitude R is obtained by averaging or calculating an altitude distribution value around the microvia 25 of the copper covering area 271 (outside 2r of FIG. 4 (a)), and obtaining each microvia ( Calculate the relative reference altitudes for

Taking the depression situation as an example (the projection situation is the opposite of this), the relative reference altitude R is moved downward to define the altitude threshold T in the allowable depression amount h. In the case of determining d as an effective depression zone in Fig. 4 (a), if the altitude value is lower than the T surface, all can be regarded as an effective depression zone.

As shown in Fig. 4B, the fact that it is determined that the effective depression area is in the copper covering area 271 does not necessarily determine that there are any depression defects. In general, the area occupied by the effective dent should be calculated to determine if there is actually a dent defect. For example, if there is a small invasion 41 in the copper cover area 271, it is evident that the minimum altitude in the invasion 41 is much smaller than the altitude threshold T. If only relying on the comparison with the high threshold T and not performing further analysis on the total area ratio occupied by the bottom of the invasion 41, the result will be recognized as an excessive and unreasonable defective defect and will be judged as an excessive defective cell 26. This results in a cost burden. In fact, if there is only one small invasion 41 in the copper covering area 271 and the altitudes in the other areas are all greater than the altitude threshold T, the invasion 41 does not prevent the normal operation of the vertical conduction function. The allowable area of the invasion 41 may be set by the user.

As shown in Fig. 5, the plurality of area basic cells 51 are classified by surveying the point position based on the altitude value within the range including the cross-sectional area of the microvia 25 (circle area having a diameter of 2r). That is, the base cells 51 of each area all have at least one altitude value. Each difference value may be obtained by comparing the relative reference altitude R with the altitude value of each area basic cell 51. For example, the numbers shown in FIG. 5 immediately indicate a difference value (or display the magnitude of the difference value by color or sign so that the user can easily understand it). If the difference is greater than the allowable depression amount h (assuming h = 4 in this embodiment) and the area is larger than the predetermined value, it can be determined that there is a depression defect. That is, if the difference value is larger than the cumulative quantity of 4 (all seven numbers are larger than 4 in FIG. 5) and larger than the predetermined value (assuming 5), it is determined that there is an effective depression in the covering area 271.

After performing the above-described advanced analysis on the copper covering area selected by each microvia 25 on the laminated sheet 20, the position of the copper filled microvia 25 having the depression defect using a screen or a graphic display To present. As shown in FIG. 6, an X defect or a notation indicates a position where a recessed defect occurs. Of course, you can also replace the X notation with a color. For example, recessed defect microvias 25 may be marked in red (or protrusion defective microvias filled in blue), and other normal microvias 25 may be marked in green. Of course, it is also possible to indicate the size of the depression amount in other colors, symbols or notation. For example, it is possible to mark the place where the amount of depression is the highest in dark red, and the place where the amount of relatively small depression is displayed in yellow as the color gradually fades from dark red to light red.

After each laminated sheet 20 is gradually formed as a final substrate, if a recessed defect occurs in one layer of the laminated sheet 20, the printed circuit board cells in which the recessed defect is located are determined to be discarded, so that each printed circuit Statistics are obtained for the presence of depression defects or protrusion defects in the substrate cell 76. As shown in FIG. 7, if there is a depression defect or projection defect, the unusable or discarded printed circuit board cell 76 is indicated by an X symbol or notation.

The present invention can not only analyze the quality of the copper plating layer 24 before etching, but also analyze whether the copper plating layer 24 after etching has a recessed defect. As shown in FIG. Since there is a copper plating layer 84 after etching within the selected range 87 specified in the microvia 85 on the laminated sheet 80, the outer surface elevation of the copper plating layer 84 is higher than that at which depression can occur. Much lower. As shown in FIG. However, while the steps of the above embodiment are only for the calculation method of the relative reference altitude R, in this embodiment, the relative reference altitude R is selected by selecting the average of the altitude distribution values in the annular zone in the range 87 to 2Rc in the coverage area 87. Get. That is, the section where both altitudes are much lower than the minimum threshold value L is not included in the relative reference altitude average value. In the same manner, it is possible to determine whether the effective depression region of the copper plating layer 84 is within the selection range even with the high threshold value T 'alone. If the effective depression area exceeds a predetermined value, it may be determined that the microvia 85 has a depression defect.

The technical content and technical features of the present invention are as described above. However, if the person skilled in the art of the present invention can be exchanged and modified based on the teaching and presentation of the present invention without violating the nature of the present invention, the scope of protection of the present invention is not limited to the contents set forth in the Examples All changes and modifications that do not violate the invention should be included, including the claims below.

The present invention provides a type of microvia that can analyze the actual depth of depression and the effective area of the copper plating layer on each microvia by excluding the influence of deformation of the laminated sheet of the printed circuit board. Provide an analysis method for the phenomenon.

In addition, the present invention displays the site where the depression or protrusion defects are present on the screen, and further displays the result of the loss of the function of the cell of the printed circuit board by the depression so as to further display the depression or protrusion defect distribution of the copper plating layer. Provide a way to present.

Claims (8)

1 step of scanning the altitude distribution of the surface of the laminated sheet after the copper filling step; Selecting a plurality of altitude values within a local copper cladding area at a position where at least one micro via or laser via of the laminate is present; Obtaining a relative reference altitude by calculating a plurality of altitude values outside the microvia range within the local copper cover area; Calculating each difference value between the relative reference altitude and a plurality of altitude values in the copper cladding area within the microvia range; And If the calculated difference is greater than the cumulative quantity of the allowable decay amount, if the cumulative quantity exceeds the predetermined value, the depression phenomenon of the copper-filled microvia includes a five step of determining that the copper covering area on the microvia is depressed. Analytical method for. The method of claim 1, The method for analyzing the depression phenomenon of the copper filling microvia further comprising the step of marking the occurrence of the defect defects in the image (image) of the laminated plate by the sign or color. The method of claim 1, And marking the cells discarded due to the presence of recessed defects in the notation or color on the printed circuit board image of the laminated sheet material. The method of claim 1, Analysis method for the depression phenomenon of the copper filled microvia which can indicate the magnitude of each difference value by number, color or sign, and can indicate the position where each difference value exists within the range including the cross-sectional area of the microvia. . The method of claim 1, The allowable depression is subtracted from the relative reference altitude, which is equal to the altitude threshold, and if the cumulative quantity exceeds the predetermined value, an area smaller than the altitude threshold within the coverage area of the microvia is larger than the allowable depression defined by the depression defect. Analytical Method for Depression of Copper-Filled Microvias. The method of claim 1, The copper coating area on the laminated sheet is an analysis method for the depression of the copper filled microvia after the etching step. The method of claim 6, Removing the elevation within the non-copper coverage area at the lowest threshold value and not including it in the calculation of the relative reference altitude. The method of claim 1, And said relative reference altitude is an average of a plurality of altitude values outside said microvia range within a local copper covering area.

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