JP2013210260A - Inspection method of substrate with bumps and inspection equipment for substrate with bumps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an inspection with high efficiency while preventing a substrate with bumps, which should pass the inspection originally, from being rejected.SOLUTION: Based on a shape of ring-like reflection light of bumps by ring-like illumination from an upper side of the bumps, all bump heights are measured to determine the success/failure of a substrate with the bumps (S1, S2). All bumps of the substrate with bumps which is determined as a success are irradiated with scan light from an inclining direction and based on positions from reflection light from bump tops and reflection light from bump bottoms, the heights of all the bumps are measured to determine the success/failure of the substrate with bumps (S3, S5). Regarding the rejected substrate with bumps, from a relational expression about a relation of a diameter of the ring-shaped reflection light of the bumps not suited to a predetermined height reference, the diameter of the ring-shaped reflection light of the bumps obtained from the actual measurement beforehand and the bump heights, compensation is performed to estimate whether the rejected bump has a predetermined height (S7) and while considering the estimation, the success/failure of the substrate with the bumps is determined (S7).

Description

  The present invention relates to a method for inspecting a substrate with bumps and an inspection apparatus for a substrate with bumps, and more particularly to a substrate with bumps for inspecting whether or not all bumps on a substrate to be inspected have a predetermined height. It relates to the inspection method.

  There is a circuit board called a BGA (Ball grid array). In this BGA, solder melted by a dispenser is applied to terminals arranged in a lattice pattern on the bottom surface of a package, and electrodes (bumps) formed in a hemisphere by the surface tension of the solder are formed. Thousands to tens of thousands of bumps are arranged on the substrates, and these are used for electrical joining when the substrates are joined together. In addition to the hemisphere, other shapes such as a spheroid shape, a pyramid shape, and a column shape may be adopted as the bump shape. In addition, the term “bump” as used herein includes joints other than electrodes, such as bumps and pillars formed on a wafer other than the substrate.

  Conventionally, various apparatuses are used to inspect whether or not such bumps are properly formed. One of them is a measuring device that three-dimensionally measures the state of bumps. Patent Document 1 discloses a measuring apparatus that captures illumination light from a laser light source with a CCD camera and acquires three-dimensional information of bumps from the image.

  As an apparatus for inspecting bumps, there is an apparatus for measuring bumps two-dimensionally. Japanese Patent Application Laid-Open No. 2004-228688 discloses a method in which a ring-shaped reflected light of a bump by ring-shaped illumination from above the bump is imaged with a CCD camera and the state of the bump is inspected based on the shape of the ring-shaped reflected light. By this inspection, bump defect information and height information can be obtained.

See JP-A-2002-107126 See JP 2008-261787 A

  However, the above-described inspection apparatus for three-dimensional inspection has the following problems. That is, it takes time to inspect small bumps with this inspection apparatus, and it is difficult to measure the difference between the ground and the inspection object in a place where the bumps are densely packed. Furthermore, although the height can be measured with high accuracy, the reflected light of the laser is difficult to detect depending on the surface material. For this reason, the inspection efficiency is poor.

  In addition, when the inventor observed the rejected bump with a microscope using such a three-dimensional inspection apparatus, there was only a slight difference in the surface state of the bump or a small defect, and there was no functional problem. It was confirmed that there were many cases where there was no.

  That is, in a three-dimensional inspection apparatus, a bumped substrate that does not have a functional problem may be rejected, and it is considered that the determination criterion for rejection is excessively high.

  The present invention has been made in view of the above-described problems, and does not fail a substrate with a bump that may be allowed to pass by itself, and a method for inspecting a substrate with a bump that can perform inspection with high efficiency, And it aims at providing the inspection apparatus of a board | substrate with a bump.

  The invention according to claim 1, which solves the above problem, is a method for inspecting a substrate with bumps for inspecting whether or not all the bumps on the substrate have a predetermined height dimension. A first inspection step for measuring all bump heights based on the shape of the ring-shaped reflected light of the bumps, and passing the bumped substrate when all the bumps have a predetermined height; All the bumps of the substrate with bumps that passed in the inspection step 1 are irradiated with scanning light from the inclination direction, and the height of the rejected bumps is determined based on the positions of the reflected light from the bump top and the reflected light from the bump bottom. A second inspection step in which the bumped substrate is accepted when all the bumps have a predetermined height, and a bumped substrate that has failed in the second inspection step. A shape of the ring-shaped reflected light based on the inspection in the first inspection step of the bump that does not meet the height standard of the bump and a predetermined height in the actual measurement in the first inspection step and the second inspection step. Based on the relational expression obtained with respect to the relationship between the ring-shaped reflected light shape of the determined bump and the bump height, the rejected bump estimates a predetermined height, and the rejected bump is provided based on this estimation. And a complementary step of determining pass / fail of the substrate with bumps.

  Similarly, the invention according to claim 2 is an apparatus for inspecting a substrate with bumps for inspecting whether or not all the bumps on the substrate have a predetermined height dimension. A first inspection means for measuring all bump heights based on the shape of the ring-shaped reflected light and passing the bumped substrate when all the bumps have a predetermined height; and the first inspection Irradiate all the bumps of the board with bumps that passed by means of scanning light from the tilt direction, measure the height of the rejected bumps based on the position of the reflected light from the top of the bump and the reflected light from the bottom of the bump, When all the bumps have a predetermined height, the second inspection means that passes the bumped substrate, the first inspection means, and the second inspection means actually determine that they have a predetermined height. Bump A complementary database that acquires and stores a relational expression regarding the relationship between the shape of the reflected light and the bump height, and a predetermined height standard for the substrate with bumps that is rejected by the second inspection means The shape of the ring-shaped reflected light based on the inspection in the first inspection step of the non-conforming bump is applied to the relational expression from the complementary storage means, and the rejected bump estimates a predetermined height, Complementing means for determining pass / fail of a substrate with bumps including the rejected bumps based on estimation, and an inspection apparatus for a substrate with bumps.

  According to the present invention, even if a substrate with bumps that is not practically problematic is rejected by an excessively high inspection standard of a three-dimensional inspection apparatus, the actual bump height is estimated and used as a reference. Since the pass / fail determination is performed, bump inspection can be performed with high efficiency without rejecting a substrate with bumps that may be passed.

It is a schematic diagram which shows the board | substrate with a bump which is a test object, (a) is a top view, (b) is a front view. It is a block diagram which shows the inspection apparatus of the board | substrate with bump which concerns on embodiment. The first inspection apparatus will be described. (A) is a schematic diagram showing a basic configuration, (b) is a schematic diagram showing an observed ring, (c) is a schematic diagram showing a principle, and (d) is a schematic diagram showing the principle. It is a photograph which shows an actual picked-up image. The second inspection apparatus will be described. (A) is a schematic diagram showing the principle, (b) is a schematic diagram showing an observed image, and (c) is a photograph showing an actual measurement image. It is a table | surface which shows an example of the data collected by a complementary data preparation means. It is a graph which shows the complementary formula produced based on the data shown in FIG. It is a complementation table created based on the complementation formula of FIG. It is a flowchart which similarly shows operation | movement of the inspection apparatus of a board | substrate with a bump. It is the photograph which overlapped the pass / fail result of the 2nd inspection device on the photograph of the 1st inspection device.

  Hereinafter, an inspection method for a substrate with bumps and an inspection apparatus for a substrate with bumps according to embodiments for carrying out the present invention will be described.

  First, a printed circuit board as a substrate with bumps to be inspected will be described. 1A and 1B are schematic views showing a substrate with bumps to be inspected, wherein FIG. 1A is a plan view and FIG. 1B is a front view. In FIG. 1, for the sake of drawing, the size of the bump is enlarged and the number thereof is reduced. A printed circuit board 200 that is an actual substrate with bumps is obtained by forming several thousand to several tens of thousands of bumps 220 that are substantially hemispherical electrodes formed on a substrate 210 with solder or the like.

  Here, the bump 220 formed on the substrate 210 is formed with a diameter d and a height dimension h, and the bump 220 substrate inspection method and the bump substrate inspection apparatus according to the embodiment are configured with the bump 220. The height dimension h is measured.

  Next, the inspection apparatus for a substrate with bumps according to the embodiment will be described. FIG. 2 is a block diagram showing the inspection apparatus for a substrate with bumps according to the embodiment.

  A bumped substrate inspection apparatus 100 according to an embodiment will be described. The inspection apparatus 100 includes a sample chamber 10 in which the printed circuit board 200 is transported as a sample, a first inspection apparatus 20 that performs a first inspection on the printed circuit board 200 in the sample chamber 10, and a printed circuit board 200 that is similar to the second inspection apparatus 200. Printed circuit board based on second inspection apparatus 30 for performing inspection, complementary data creating means 40, inspection results from first inspection apparatus 20 and first inspection apparatus 20, and complementary data from complementary data creating means 40 Complementing means 50 for performing 200 pass / fail judgments.

  Next, the first inspection apparatus 20 will be described. 3A and 3B illustrate the first inspection apparatus, in which FIG. 3A is a schematic diagram illustrating a basic configuration, FIG. 3B is a schematic diagram illustrating an observed ring, and FIG. 3C is a schematic diagram illustrating a principle. d) is a photograph showing an actual photographed image.

  The first inspection apparatus 20 measures the diameter, height, and shape of all the bumps based on the bump outline and ring-shaped reflected light from the ring-shaped illumination from above the bump. Specifically, the first inspection apparatus 20 includes a ring-shaped illumination unit 21, a microscope 22 for capturing an image of a bump illuminated by the ring-shaped illumination unit 21, and an image sensor 23 (CCD, C-MOS). And an illumination unit (not shown) from the vertical direction in the microscope 22. The ring illumination unit 21 can adjust the attitude of the ring illumination.

  Ring-shaped illumination light is emitted from the ring-shaped illumination unit 21. The illumination angle can vary widely from illumination with a low inclination angle of about 0 ° to 30 ° to illumination with a high inclination angle of 60 ° to 90 °.

  The reflected light from the surface of the bump 220 is imaged by the image sensor 23 through the microscope 22. In addition to the contour shape of the bump 220, a ring-shaped ring 24 forms an image on the image sensor 23 as shown in FIG. FIGS. 3A and 3B show the case where one bump 220 is photographed. However, when a printed board 200 (see FIG. 1) having a large number of bumps 220 is photographed, as shown in FIG. In addition, the reflected light from many bumps 220 is imaged as many rings.

  In the first inspection apparatus 20, the height dimension h of the bump 220 is obtained by calculation processing based on the diameter D of the ring 24 imaged by the reflected light from the bump 220, and the bump 220 is formed based on the shape of the ring 24. Measure distortions and defects. That is, as shown in FIG. 3C, in the two bumps 220A (height hA) and 220B (height hB) having different diameters and heights, the rings formed by the light L from the same direction have different diameters. DA, DB. The observed diameter D of the ring 24 and the height dimension h are uniquely determined by the irradiation direction of the light L and other conditions. For this reason, the height dimension h of the bump 220 can be calculated from the diameter D of the ring 24. When the bump has a shape other than the hemisphere, the shape distortion and height are determined by the shape and size of the reflected light corresponding to each shape.

  The first inspection apparatus 20 can measure the position and size (diameter) of the bump, inspect the difference from the non-defective sample, and further measure the height of the bump. Then, the first inspection apparatus 20 determines that the bump 220 diameter or shape does not reach the reference, or the height does not reach a predetermined reference. For example, the height dimension h of the bump 220 is a predetermined value H or less. In some cases, it will be rejected.

  Next, the second inspection apparatus 30 will be described. 4A and 4B illustrate the second inspection apparatus, where FIG. 4A is a schematic diagram illustrating the principle, FIG. 4B is a schematic diagram illustrating an observed image, and FIG. 4C is a photograph illustrating an actual measurement image. is there. The second inspection apparatus 30 scans the light L from the laser oscillator 31 with a polygon mirror (not shown), irradiates the bumps 220 from oblique information, images the reflected light with the camera 32, and shows it in FIG. 4 (b). As described above, the height of the bump 220 is obtained based on the difference in luminance between the top 220a of the bump 220 and the luminance of the bottom 220b.

The camera 32 of the second inspection apparatus 30 can acquire an image as shown in FIG. Then, the height h of each bump 220 is acquired from the obtained image. The second inspection apparatus 30 is rejected when the height dimension h of the bump 220 is a predetermined height reference, for example, the height H or less. In addition, as a height reference | standard, the highest value other than minimum value H can be defined.

  When the first inspection apparatus 20 and the second inspection apparatus 30 are combined, and the printed circuit board 200 that has passed the first inspection apparatus 20 is further inspected by the second inspection apparatus 30, the first inspection apparatus In 20, the inspection can be performed by accurately measuring the height of the bump while inspecting the position and size (diameter) of the bump and the difference from the non-defective sample.

  In the inspection apparatus 100, in addition to the first inspection apparatus 20 and the second inspection apparatus 30, complementary data creation means for the rejected bumps of the printed circuit board 200 that has been rejected by the second inspection apparatus 30 by the complementary means 50. Complementation is performed based on data from 40.

  The complementary data creation means 40 has a bump diameter d determined by the first inspection apparatus 20 and the second inspection apparatus 30 that is actually determined to have a height dimension equal to or higher than the reference height dimension H, and the bump height. The relational expression about the relation with the dimension h is stored. Then, the complementing means 50 applies the diameter of the ring 24 acquired by the first inspection device 20 of the rejected bump to this relational expression, acquires the complemented height dimension h2, and uses the height dimension h2 as the reference height. Compared with the dimension H, the pass / fail of the printed circuit board 200 is determined.

  FIG. 5 is a table showing an example of data collected by the complementary data creating means, FIG. 6 is a graph showing a complementary formula created based on the data shown in FIG. 5, and FIG. 7 is created based on the complementary formula of FIG. It is a comparison table | surface with the measured height dimension and the value obtained with the 2nd measuring apparatus.

First, the complementary data creating means 40 creates a complementary table shown in FIG. A complement table is created as follows. First, the diameter d and the height dimension of the bumps acquired by the first inspection apparatus 20 for the printed circuit board 200 that has been accepted by the first inspection apparatus 20 and whose bump height dimensions were measured by the second inspection apparatus 30. Create a correspondence table with h. Based on this table, for example, by the least square method, as shown in FIG. 6, the correlation between the bump diameter obtained by the first inspection apparatus and the height dimension of the bump obtained by the second inspection apparatus. Get. The correlation equation is not limited to the least square method, and can be obtained by other statistical methods such as polynomial approximation. In this example, when the bump height is y and the bump diameter is x,
Correlation equation y = 0.4774x + 53,972 (R ^ 2 = 0.4474)
Got.

  As shown in FIG. 7, the error between the correlation formula and the bump height obtained by the second inspection apparatus was slight. That is, the accuracy required for the height inspection is generally about 10% with respect to the bump height. On the other hand, the accuracy obtained from the correlation equation is 3% or less, which is sufficient accuracy.

  Next, the operation of the inspection apparatus 100 will be described. FIG. 8 is a flowchart showing the operation of the inspection apparatus for a substrate with bumps according to the embodiment, and FIG. 9 is a photograph in which a pass / fail result of the second inspection apparatus is superimposed on a photograph of the first inspection apparatus.

  First, the printed circuit board 200 is inspected by the first inspection apparatus 20 (S1). In this inspection, the diameter, shape, height dimension, etc. of all the bumps on the printed circuit board 200 are inspected. If even one bump on the printed circuit board 200 fails (S2: no), the printed circuit board 200 fails (S8). Then, data regarding the diameter of the bump is sent to the complementary data creating means 40.

  The passed printed board 200 is inspected by the second inspection apparatus 30 (S3). This inspection measures the height of the bump. Then, data regarding the height dimension of the bump is sent to the complementary data creating means 40. The complementary data creating means 40 creates complementary data (S4). If even one bump on the printed circuit board 200 fails (S5: no), the printed circuit board 200 fails (S8).

  When the height dimensions of all the bumps pass in this inspection (Yes in S5), the printed circuit board 200 passes (S6). On the other hand, if even one bump is rejected, the printed circuit board 200 is supplemented for the bumps rejected by the complementing means 50 (S7). Complementation is performed by obtaining the bump height dimension based on the correlation equation shown in FIG. 7 for the rejected bump.

  When comparing the bump that failed in the second inspection shown in FIG. 9 with the adjacent passed bump, it is good enough that the image acquired by the first inspection apparatus 20 is almost indistinguishable. In such a state, the height of the rejected bump is supplemented with the result of the first inspection apparatus in this state.

  For example, the bump indicated by B in the table of FIG. 6 has a height of 105.52 obtained by the first inspection apparatus 20, but the second inspection apparatus obtains the height dimension for some reason. Has failed. This bump is complemented by the complementing means 50. In the complementary data creation means 40, when this bump diameter is applied to the correlation equation, 104.347248 is obtained.

  When all the bumps that fail such a complement are passed and all the bumps pass (Yes in S7), the printed circuit board 200 passes (No in S6). On the other hand, if at least one bump is rejected despite the complement, the printed circuit board 200 is rejected (S8). Thus, a series of inspections is completed.

  As described above, according to the method for inspecting a substrate with bumps according to the embodiment, an actual bump height is estimated for a substrate with bumps that is not practically practical, and pass / fail judgment is performed based on this. The bump inspection can be performed with high efficiency without rejecting the substrate with bumps that should be passed.

10: Sample chamber 20: First inspection device 21: Ring illumination unit 22: Microscope 23: Image sensor 24: Wheel 30: Second inspection device 31: Laser oscillator 32: Camera 40: Supplementary data creation means 50: Complementation Means 100: Inspection apparatus 200: Printed circuit board 210: Board 220: Bump

Claims (2)

In the method of inspecting a substrate with bumps for inspecting whether all the bumps on the substrate have a predetermined height dimension,
Measure the diameter and height of all bumps based on the shape of the ring-shaped reflected light of the bump from the ring illumination from above the bump, and when all the bumps have the specified diameter and height A first inspection step that passes the attached substrate;
All the bumps of the substrate with bumps that have passed in the first inspection step are irradiated with scanning light from the tilt direction, and the height of the failed bumps is determined based on the positions of the reflected light from the bump top and the reflected light from the bump bottom. A second inspection step of measuring the thickness and passing the bumped substrate when all the bumps have a predetermined height;
Complement to obtain the correlation between the bump diameter and the bump height dimension from all the bump diameters obtained in the first inspection step and all the bump height dimensions obtained in the second inspection step A data creation step;
The complementary data creation device calculates the diameter of the bump obtained in the inspection in the first inspection step of the bump-imposed substrate that has failed in the second inspection step and does not meet a predetermined height standard. Applying to the created relational expression, estimating the predetermined height of the rejected bump, and a complementary step of determining pass / fail of the substrate with the bump including the rejected bump based on the estimation,
A method for inspecting a substrate with bumps, comprising: In the inspection apparatus for a substrate with bumps for inspecting whether all the bumps on the substrate have a predetermined height dimension,
Measure the diameter and height of all bumps based on the light reflected from the ring by ring illumination from above the bump, and pass the bumped board when all the bumps are of the specified diameter and height. First inspection means, and
All bumps of the substrate with bumps that have passed by the first inspection means are irradiated with scanning light from the tilt direction, and the height of the rejected bumps based on the positions of the reflected light from the bump top and the reflected light from the bump bottom. A second inspection means for measuring the thickness and accepting the bumped substrate when all the bumps have a predetermined height;
Complement to obtain the correlation between the bump diameter and the bump height dimension from all the bump diameters obtained by the first inspection means and all the bump height dimensions obtained by the second inspection means A data creation device;
The complementary data creation device calculates the diameter of the bump acquired by the inspection by the first inspection device of the bump that does not conform to a predetermined height standard of the substrate with bumps that has failed the second inspection means. Applying to the created relational expression, estimating the predetermined height of the rejected bump, and a complementary means for determining pass / fail of the substrate with the bump including the rejected bump based on this estimation,
An inspection apparatus for a substrate with bumps, comprising: