JP5065329B2 - Shape inspection apparatus and shape inspection program - Google Patents

Description

  The present invention relates to a technique for measuring the shape of an object, and more particularly to a technique for inspecting the outer shape of an IC (Integrated Circuit).

  The IC chip includes a plurality of input / output terminals. IC chips are required not only to be smaller, lighter and thinner, but also to have more terminals. In order to meet such a demand, not only a technique for uniformly manufacturing a large number of small terminals, but also a technique for inspecting the uniformity (coplanarity) is important. The variation in terminal shape may cause an electrical failure not only in the IC chip but also in the entire package substrate on which the IC chip is mounted. For this reason, it is necessary to execute a coplanarity test on all IC chips at high speed, accuracy, and low cost.

  Patent Document 1 relates to a technique for inspecting the shape of a solder ball which is a terminal of a CSP (Chip Scale Package), illuminates the solder ball from a plurality of directions, measures reflected light, and determines the shape of the solder ball based on a mathematical model. Measuring. Patent Document 2 relates to a technique for inspecting the shape of solder, illuminates the solder, measures reflected light, and measures the shape of the solder based on a mathematical model.

JP 2004-239810 A JP 2006-208187 A

  In Patent Document 1, on the assumption that the solder ball is close to a good shape model to some extent, various parameters such as surface reflection parameters are estimated, and the shape of the solder ball is measured based on these parameters (Patent Document 1). Paragraph [0023] etc.). In order to increase measurement accuracy, an appropriate good shape model must be prepared. In Patent Document 2, board data for specifying the position of solder must be prepared, and various parameters of a mathematical model must be set appropriately (paragraphs [0027], [0045], etc. of Patent Document 2). reference). In either case, measurement accuracy is easily affected by initial conditions such as models and parameters.

  The present invention has been completed in view of the above problems, and its main object is to provide a technique for efficiently inspecting the shape of an object with a simple configuration.

  The shape inspection apparatus according to the present invention changes one or more positions of an inspection target object having a curved protrusion on the outer shape, a light source that irradiates light to the protrusion, and a camera that captures reflected light from the protrusion. Thus, a position control unit that changes both or one of the light source direction from the projection to the light source and the viewpoint direction from the projection to the camera, and the projection on the projection each time both or one of the light source direction and the viewpoint direction is changed. Identify the luminescent spot and calculate the height of the protrusion from the inclination calculation section that calculates the inclination of the luminescent spot of the protrusion based on the light source direction and the viewpoint direction at that time, and the inclination of the protrusion at the multiple luminescent spots And an altitude calculation unit. The “inspection object” may be, for example, an IC (Integrated Circuit) in which solder ball elements are arranged in a plane, and the “projection” may be a solder ball element.

  A reference plane parallel to the tangent plane at the highest point of the protrusion is set in advance, and when the reference surface reflects light in the viewpoint direction, the bright spot that reflects light in the viewpoint direction from the protrusion is the highest point of the protrusion. May be specified.

  In addition, assuming that the inclination of the protrusion at the highest point is the same as the inclination of the surface on which the protrusion is installed in the object to be inspected, the surface on which the protrusion is installed is the reference plane, and the highest of the protrusion from the reference surface The height to the point may be the height of the protrusion.

  When the object to be inspected has a plurality of protrusions, each time one or both of the light source direction and the viewpoint direction is changed, a bright spot is specified for each of the plurality of protrusions of the inspection target object, and the inclination at each bright spot is calculated. May be. A warning may be generated when a height that deviates a predetermined amount or more from a predetermined reference value is detected for any of the protrusions.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, and the like are also effective as an aspect of the present invention.

  According to the present invention, it becomes easy to efficiently inspect the shape of an object to be inspected with a simple configuration.

It is a schematic diagram which shows the relationship between incident light, reflected light, and a viewpoint. It is a schematic diagram for demonstrating the method of specifying the inclination of a to-be-inspected surface based on the incident / reflection direction of light. It is an external view of SIP. It is a hardware block diagram of the system which detects the inclination of a pin. It is a functional block diagram of a shape inspection apparatus. It is a flowchart which shows the process which test | inspects the inclination of a plane. It is an external view of BGA. It is a schematic diagram which shows the reflection state of the light in the curved solder ball. It is a hardware block diagram of the system which detects the inclination and height of a solder ball. It is a schematic diagram for demonstrating the method to measure the height of a solder ball. It is a flowchart which shows the process which test | inspects the inclination and the height of a processus | protrusion about the processus | protrusion which has a curved surface shape.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing the relationship between incident light, reflected light, and viewpoint. In the present embodiment, the inspection target object is irradiated with light, and the shape of the inspection target object is measured based on the reflected light. Before explaining the specific processing contents, first, the measurement principle will be explained.

The inspection target surface 200 is a glossy flat surface and reflects light specularly. Here, the normal vector at the point O on the inspection target surface 200 is n _d . Direction of the normal vector n _d is the direction Od going from point O to the point d in FIG. Knowing the direction of the normal vector n _d, identifiable slope at point O of the inspection target surface 200.

The point O is irradiated with light from the light source installed at the point a. Hereinafter, the direction from the point to be observed on the inspection target surface 200 to the point where the light source is installed, such as the direction Oa from the point O to the point a, is referred to as “light source direction”. The angle formed between the normal vector n _d and the light source direction, that is, the incident angle of light is α. Light is specularly reflected from the inspection target surface 200 at a reflection angle α having the same size as the incident angle α. In FIG. 1, light is reflected from point O toward point b. Hereinafter, a direction in which light is reflected from a point to be observed on the inspection target surface 200, such as a direction Ob from the point O to the point b, is referred to as a “reflection direction”. The inspection target surface 200 is observed from the point c. Hereinafter, the direction from the point to be observed on the inspection target surface 200 toward the viewpoint, such as the direction Oc from the point O to the point c, is referred to as “viewpoint direction”. Let γ be the angle formed by the reflection direction and the viewing direction.

Ｉａは環境光成分、Ｉｄは拡散反射成分、Ｉｓは鏡面反射成分である。検査対象面２００は光沢を有するため、Ｉａ、ＩｄはＩｓに比べて十分に小さいとする。したがって、以降においては、Ｉｓのみを考慮する。 According to the Phong model, the reflection component I of light is expressed by the following equation (1).

Ia is an ambient light component, Id is a diffuse reflection component, and Is is a specular reflection component. Since the inspection target surface 200 is glossy, Ia and Id are assumed to be sufficiently smaller than Is. Therefore, only Is is considered in the following.

Ｋｓは鏡面反射成分係数、Ｅは照明光の強度、ｎは対象物体に依存する係数である。Ｋｓ、Ｅ、ｎはいずれも定数であるため、Ｉｓが最大になるのはγ＝０、すなわち、反射方向と視点方向が一致するときである。反射方向と視点方向が一致するとき、光源方向と視点方向（反射方向）の中心方向を、法線ベクトルｎ_ｄの方向として特定できる。 The specular reflection component Is is expressed by the following equation (2).

Ks is a specular reflection component coefficient, E is the intensity of illumination light, and n is a coefficient depending on the target object. Since Ks, E, and n are all constants, Is is maximized when γ = 0, that is, when the reflection direction and the viewpoint direction coincide. When the reflection direction and the view direction is coincident, the central direction of the light source direction and the viewpoint direction (reflection direction) can be specified as the direction of the normal vector n _d.

FIG. 2 is a schematic diagram for explaining a method of specifying the inclination of the inspection target surface 200 based on the light incident / reflection direction. In FIG. 2, the light source direction and the viewpoint direction are set so that γ = 0, that is, the viewpoint direction (point O → point c) and the reflection direction (point O → point b) coincide. The positional relationship among the light source, viewpoint, and inspection object at this time is called a “maximum reflection position”. The light irradiated from point a to point O is reflected in the direction from point O to point c (point b). An incident angle and a reflection angle with respect to the inspection target surface 200 are α. Normal vector n _d is the angle of the inspection target surface 200 with predetermined inclination reference plane 202 (hereinafter, referred to as "surface inclination angle") and the theta _N. In addition, an angle formed between the tilt reference surface 202 and the light source direction at the maximum reflection position (hereinafter referred to as “specific light source angle”) is θ _L , and an angle formed between the tilt reference surface 202 and the viewpoint direction (reflection direction) at the maximum reflection position ( Assuming that “ _V ” (hereinafter referred to as “specific viewpoint angle”) is θV, the following equations (3) and (4) are established, as is apparent from FIG.

When α is eliminated from the equations (3) and (4), the equation (5) is obtained.

If the inspection target surface 200 and the viewpoint direction are fixed, the maximum reflection position is found while changing the light source direction, and the specific light source angle θ _L at that time is obtained, the specific viewpoint angle θ _V is a fixed value. It can be calculated surface inclination angle theta _N based on). In order to find the maximum reflection position, any of the light source, the viewpoint, and the inspection target surface 200 may be moved, or two or more of these may be moved. In the present embodiment, the viewpoint direction and the inspection target surface 200 are fixed, and only the light source is moved, that is, only the light source direction is changed.

  Hereinafter, as the present embodiment, (1) a method for specifying the inclination of the plane and (2) a method for specifying the inclination of the curved surface will be described, but the basic measurement principle is the same.

  FIG. 3 is an external view of the SIP 204. (1) A method for specifying the inclination of a plane will be described with a pin 206 of a SIP (Single Inline Package) 204 as an inspection target. As shown in FIG. 3, the x-axis, y-axis, and z-axis are set in the longitudinal direction, width direction, and height direction of the SIP 204, respectively. The SIP 204 is a pin insertion type IC that is mounted by inserting a plurality of pins 206 into through holes of a printed board. These pins 206 function as external connection terminals of the SIP 204. The pins 206 of the SIP 204 have a flat plate shape and are glossy because they are made of metal. Of each surface of the pin 206, the area of the pin side surface portion 210 is the largest and the area of the pin tip portion 208 is the smallest. If there is a pin 206 that is greatly warped in the y-axis direction, the SIP 204 cannot be mounted in the through hole. Therefore, it is necessary to remove such a SIP 204 as a defective product. In the case of FIG. 3, the pin 206a is bent in the positive y-axis direction and the pin 206b is bent in the negative y-axis direction.

  As a method of detecting “warping” of the pin 206, a method of setting a line of sight in the positive z-axis direction and confirming the position of each pin tip portion 208 is conceivable. If the pin 206 is not warped, the pin tip 208 is arranged in a straight line, but if the pin 206 is warped, the position of the pin tip 208 varies. However, since the pin tip portion 208 has a small area, it is difficult to accurately detect the warp of the pin 206 by such a confirmation method. Therefore, in the present embodiment, not the pin tip portion 208 but the pin side surface portion 210 is set as the inspection target surface 200, and the inclination of each pin side surface portion 210 in the y-axis direction is detected.

  FIG. 4 is a hardware configuration diagram of a system that detects the inclination of the pin 206. In this system, the positions of the SIP 204 and the camera 222 are fixed, and only the light source 220 moves. The front side of the drawing corresponds to the positive direction of the x axis, the upward direction corresponds to the positive direction of the y axis, and the right direction corresponds to the positive direction of the z axis. The length of the pin 206 is about 1 mm, the distance from the SIP 204 to the camera 222 is about 300 mm, and the distance from the SIP 204 to the light source 220 is about 700 mm. Therefore, the distance from the SIP 204 to the camera 222 and the light source 220 is sufficiently larger than the size of the SIP 204. The light source 220 moves at a constant speed from a start point S to an end point E shown in FIG.

The shape inspection apparatus 100 is connected to the camera 222 and the light source 220. The shape inspection apparatus 100 measures the intensity of reflected light (hereinafter referred to as “reflection intensity”) via the camera 222 by irradiating the pin 206 with light while moving the light source 220. The shape inspection apparatus 100 determines that the maximum reflection position has been reached when the reflection intensity is maximum. By obtaining a particular light source angle theta _L at this time, it identifies the surface inclination angle theta _N pins 206 based on equation (5).

However, it is not necessarily preferred in terms of convenience for measuring the size of a particular light source angle theta _L directly. Therefore, the shape inspection apparatus 100 calculates the specific light source angle θ _L based on the moving speed and moving time of the light source 220, in other words, based on the changing speed and changing time of the light source direction. The time that has elapsed since the light source 220 departed from the starting point S is called “light source movement time”. Further, the angular velocity when the light source 220 moves on a circle centered on the SIP 204 is ω. When the movement time when the light source 220 reaches the maximum reflection position (hereinafter, particularly referred to as “peak time”) is T _L , the specific light source angle θ _{L based} on the direction from the pin 206 to the start point S is It is expressed by equation (6).

Ｔ_ＬＴは検査ピンのピーク時間、Ｔ_ＬＢは基準ピンのピーク時間である。式（７）によれば、ピーク時間を計測することで相対角度Δθ_ＮＤを特定できる。相対角度Δθ_ＮＤが所定の閾値Ｔ_１以上となる検査ピンは、基準ピンと比べて傾きの差が大きすぎると判定される。そして、このような検査ピンを有するＳＩＰ２０４は不良品として除外対象となる。基準ピンは任意に設定してもよいが、本実施の形態においては、ＳＩＰ２０４の複数のピン２０６のピーク時間の平均値を基準ピンのピーク時間としている。式（６）によれば、複数のピン２０６の傾きの平均値を基準ピンの傾きとしている、ともいえる。複数のピン２０６の平均的な傾きに比べて大きく傾いているピン２０６を有するＳＩＰ２０４は不良品と判定される。 Here, a reference pin 206 (hereinafter referred to as “reference pin”) is set, and the specific light source angle of this reference pin is defined as θ _LB. When the specific light source angle of the pin 206 to be inspected (hereinafter referred to as “inspection pin”) is θ _LT , the relative angle Δθ _ND that is the difference between the inclination of the inspection pin and the reference pin is (7)

T _LT is the peak time of the inspection pin, and T _LB is the peak time of the reference pin. According to Equation (7), the relative angle Δθ _ND can be specified by measuring the peak time. A test pin having a relative angle Δθ _ND equal to or greater than a predetermined threshold T ₁ is determined to have an excessively large difference in inclination compared to a reference pin. The SIP 204 having such an inspection pin is excluded as a defective product. Although the reference pin may be set arbitrarily, in this embodiment, the average value of the peak times of the plurality of pins 206 of the SIP 204 is used as the peak time of the reference pin. According to Equation (6), it can be said that the average value of the inclinations of the plurality of pins 206 is used as the inclination of the reference pin. The SIP 204 having the pins 206 that are greatly inclined as compared with the average inclination of the plurality of pins 206 is determined as a defective product.

  FIG. 5 is a functional block diagram of the shape inspection apparatus 100. The shape inspection apparatus 100 can be realized in hardware by elements such as a CPU of a computer, and is realized in software by a program having a data transmission / reception function. In FIG. Draw functional blocks. Therefore, these functional blocks can be realized in various forms by a combination of hardware and software. Here, the configuration of each functional block will be mainly described.

  The shape inspection apparatus 100 includes a UI (user interface) unit 110, a data processing unit 120, and a data holding unit 140. The UI unit 110 is in charge of user interface processing. The data processing unit 120 executes various data processing based on data acquired from the UI unit 110 or the data holding unit 140. The data holding unit 140 also serves as an interface between the UI unit 110 and the data holding unit 140. The data holding unit 140 is a storage area for holding various data.

The UI unit 110 includes an imaging unit 112 and a warning unit 114. In addition to this, an input unit that receives a user operation and a display unit that displays various types of information on the screen may be included. The imaging unit 112 drives the camera 222 to image an inspection target object such as the SIP 204. An image captured at this time is called an “inspection image”. The warning unit 114 issues a warning to the user when there is an abnormality in the shape of the inspection target object. When the SIP 204 is an object to be inspected, a warning is issued when there is an inspection pin whose relative angle Δθ _ND is equal to or greater than the threshold T ₁ . It may be a direct warning by display or sound, or may be an indirect warning by transmitting / recording predetermined information to an external database. The data holding unit 140 includes an image holding unit 142 and a reflection intensity information holding unit 144. The image holding unit 142 holds an inspection image. The reflection intensity information holding unit 144 holds reflection intensity information in which the light source moving time and the reflection intensity are associated with each other. The reflection intensity information is updated as needed during measurement. The reflection intensity information will be described later.

  The data processing unit 120 includes a position control unit 122, a position specifying unit 124, a reflection intensity measuring unit 126, an inclination calculating unit 128, an abnormality determining unit 134, and an altitude calculating unit 136. The position control unit 122 moves the light source 220 from the start point S to the end point E at a constant angular velocity ω. The position specifying unit 124 specifies the light source direction from the light source moving time and the angular velocity. The reflection intensity measurement unit 126 measures the reflection intensity of the inspection target surface 200 as the gray value of the pixel of the inspection image.

The inclination calculation unit 128 calculates a surface inclination angle θ _{N of} the object to be inspected, more precisely, a normal vector for specifying the surface inclination angle θ _N. The inclination calculation unit 128 includes a plane inclination calculation unit 130 and a curved surface inclination calculation unit 132. The plane inclination calculation unit 130 calculates the inclination of a plane like the pin 206. The curved surface slope calculating unit 132 calculates the slope of the curved surface. The abnormality determination unit 134 determines whether or not there is an abnormality in the inclination of the plane. When an abnormality is determined, the warning unit 114 generates a warning. The abnormality determination unit 134 determines whether or not there is a pin 206 having Δθ _ND equal to or greater than the threshold T ₁ when the SIP 204 is an inspection target object. The altitude calculation unit 136 measures the height of the curved projection. The role of the altitude calculation unit 136 will be described in detail later.

  FIG. 6 is a flowchart showing a process of inspecting the inclination of the plane. First, the position control unit 122 installs the light source 220 at the start point S at time t = 0, and moves the light source 220 at a constant angular velocity ω (S10). After a predetermined time elapses, the imaging unit 112 captures the plurality of pins 206 of the SIP 204 and acquires an inspection image (S12). The reflection intensity measurement unit 126 refers to the inspection image and records the reflection intensity for each pin 206 and the light source movement time in association with each other (S14). When the SIP 204 is imaged, an inspection image in which the portion of the pin 206 is bright can be obtained. The pin 206 is particularly bright when it reaches the maximum reflection position. Therefore, it is easy to specify the location of the pin 206 from the inspection image. If the light source 220 has not reached the end point E (N in S16), the process returns to S12. Until the light source 220 reaches the end point E, imaging of an inspection image (S12) and recording of reflection intensity information (S14) are periodically performed.

When the light source 220 reaches the end point E (Y in S16), the position control unit 122 stops the light source 220 (S18). The position specifying unit 124 specifies the peak time _TL for each pin 206 with reference to the reflection intensity information (S20). For example, for a certain pin 206, the reflection intensities measured at each timing of the light source moving times t ₀ , t ₁ ,..., T _k ,. time is assumed to be t _k. In this case, the peak time T _L = t _k for this pin 206. As described in relation to formula (6), also to determine the specific source angle theta _L by a particular peak time T _L.

The plane inclination calculating unit 130 sets the average value of these peak times T _L as the virtual reference pin peak time T _LB (S22). As described in connection with Expression (6), the specific light source angle θ _LB of the reference pin is also determined by specifying the peak time T _LB. The plane inclination calculating unit 130 calculates the relative angle Δθ _ND of each pin 206 according to the equation (7) (S24).

The abnormality determining unit 134 determines whether there is a pin 206 having a relative angle Δθ _ND larger than the threshold T ₁ (S26). If present (Y in S26), the abnormality determination unit 134 instructs the warning unit 114 to generate a warning (S28). If it does not exist (N of S26), S28 is skipped.

  When the light source 220 is moved from the start point S to the end point E, the inspection efficiency is improved by simultaneously measuring a plurality of pins 206 of one SIP 204. Further, a plurality of SIPs 204 may be measured simultaneously. For example, if five SIPs 204 having ten pins 206 are simultaneously measured, the inspection efficiency can be further improved by measuring the reflection intensity of each of 10 × 5 = 50 pins 206 using one inspection image. Can do.

  FIG. 7 is an external view of the BGA 230. (2) The method of specifying the inclination of the curved surface will be described with the solder balls 232 of a BGA (Ball Grid Array) 230 as the inspection object. As shown in FIG. 7, the x-axis and z-axis are set in the surface direction of the BGA 230, and the y-axis is set in the height direction. The BGA 230 is a surface mount type IC in which solder balls 232 are arranged in an array. The solder ball 232 functions as an external terminal of the BGA 230. The semiconductor integrated circuit in the BGA 230 is connected to the package substrate via the solder ball 232. The solder balls 232 are spherical projections and are glossy because they are made of metal. The solder balls 232 are arranged on the solder ball installation surface 234 of the BGA 230. If the height of the solder ball 232 from the solder ball installation surface 234 varies, the BGA 230 cannot be mounted on the package substrate. Therefore, it is necessary to remove such a BGA 230 as a defective product.

  In order to measure the height of the solder ball 232, first, the shape inspection apparatus 100 measures the inclination (shape) of the surface of the solder ball 232. The measurement of the curved surface is also based on the principle described in relation to FIGS.

FIG. 8 is a schematic diagram showing a reflection state of light from the solder balls 232. FIG. 8 shows a cross section of the solder ball 232 in the xy direction. Point _{P A, P B, P C} is a point on the surface of the ball 232 solder none. Point _{P A, P B,} respectively normal vector at _{P C n A, n B,} and _{n C.} Since the solder ball 232 has a curved shape, the directions of n _A , n _B , and n _C are different from each other.

When light is irradiated from the light source 220, the point _{P A,} P B, the light is reflected in a different direction respectively from _{P C.} In FIG. 8, the light reflected from the point P _B is directed straight toward the camera 222. In other words, the reflection direction and the viewpoint direction coincide with each other for the point P _B. Figure 8 would indicate a maximum reflection position of the point P _B. Observing the solder balls 232 by the camera 222, the interior point _{P B} on the surface of the solder ball 232 appears especially bright. Hereinafter, such points are referred to as “bright spots”. By comparing the density value of each pixel in the inspection image, the position of the bright spot can be specified from the inspection image.

  FIG. 9 is a hardware configuration diagram of a system for detecting the inclination and height of the solder ball 232. The configuration of this system is basically the same as the configuration shown in FIG. Only the light source 220 moves while being fixed at the positions of the BGA 230 and the camera 222. The front side of the drawing corresponds to the positive direction of the z axis, the upward direction corresponds to the positive direction of the y axis, and the right direction corresponds to the positive direction of the x axis. The height of the solder ball 232 is about 100 μm, the distance from the BGA 230 to the camera 222 is about 300 mm, and the distance from the BGA 230 to the light source 220 is about 700 mm. Compared to the size of the BGA 230, the distance from the BGA 230 to the camera 222 and the light source 220 is so large that a plurality of straight lines connecting the solder balls 232 to the light source 220 can be regarded as parallel. The light source 220 moves at a constant speed from a start point S to an end point E shown in FIG.

  The shape inspection apparatus 100 is connected to the camera 222 and the light source 220. The shape inspection apparatus 100 irradiates the solder ball 232 with light while moving the light source 220 and detects a bright spot of the solder ball 232 via the camera 222.

ここで、Δｈは、ｘ座標をΔｘだけ移動させたときのｙ座標の変化量を示す。ｙ（ｘ_１＋Δｘ）は、ｘ＝ｘ_１＋Δｘにおけるｙ座標値を示す。同様に、ｙ（ｘ_１）は、ｘ＝ｘ_１におけるｙ座標値を示す。Δｘは微小であるとする。ｎはｘ＝ｘ_１＋Δｘにおける法線ベクトル、ｍは移動ベクトルであり、それぞれ、式（９）、（１０）のように表される。

Δｈは、法線ベクトルｎと移動ベクトルｍの内積として表現される。 FIG. 10 is a schematic diagram for explaining a method of measuring the height of the solder ball 232. First, a change amount of a general curve on the xy plane can be expressed by Expression (8).

Here, Δh indicates the amount of change in the y-coordinate when the x-coordinate is moved by Δx. y (x ₁ + Δx) represents the y coordinate value at x = x ₁ + Δx. Similarly, y (x ₁ ) indicates the y coordinate value at x = x ₁ . It is assumed that Δx is very small. n is a normal vector at x = x ₁ + Δx, and m is a movement vector, which are expressed as equations (9) and (10), respectively.

Δh is expressed as an inner product of the normal vector n and the movement vector m.

ｋ_ｎは定数、θ_ｎは法線ベクトルｎがｘ軸と成す角度である。 The normal vector n can also be expressed as Equation (11).

k _n is a constant, and θ _n is an angle formed by the normal vector n with respect to the x axis.

From equation (9) and equation (11), x coordinate value and y coordinate values are compared respectively, clearing the _{k n,} obtained equation (12).

すなわち、ｘをΔｘだけ移動させたときの高さの変化Δｈは、曲線の傾きθ_ｎから特定できる。 Expression (13) is obtained from Expressions (8), (9), (10), and (12).

That is, the height change Δh when x is moved by Δx can be identified from the slope θ _{n of} the curve.

Based on the above, the shape of the solder ball 232 is measured. Although the final purpose is to measure the height of the solder ball 232, the inclination at each point on the solder ball 232 is calculated for this purpose. The bright spot in the light source travel time _{t r} to _{P r,} a bright spot in the light source travel time _{t r + 1} and _{P r + 1.} The height of the bright spot P _{r from} the solder ball installation surface 234 is h _r , and the height of the bright spot P _{r + 1} is h _{r + 1} . Further, the difference between the bright spot _{P r} and luminescent spot _{P r + 1} of x-coordinate and [Delta] x _{r + 1.} Angle to the normal vector of the bright point _{P r n r,} the normal vector _{n r} is formed between the solder ball mounting surface 234, i.e., the angle between the x axis and theta _r. Similarly, the normal vector of the bright spot P _{r + 1} is n _{r + 1} , and the angle formed by the normal vector n _{r + 1} with the x axis is θ _{r + 1} .

When the difference in height of the bright point _{P r + 1} and luminescent spot _{P r} and _{Δh r + 1, Δh r +} 1 , based on equation (13) is represented by the following equation (14).

Further, if the difference between θ _{r + 1} and θ _r , that is, the amount of change in the direction of the normal vector is Δθ _{r + 1} , Δθ _{r + 1} is expressed by the following equation (15) based on equations (5) and (6). The

The highest point of the solder balls 232 and _{P t.} The normal vector n _t at the highest point P _t is oriented in the positive y-axis direction. In other words, the plane tangent to the solder balls 232 in this highest point P _t is a plane parallel to the solder ball mounting surface 234. Thus the normal vector _{n t} is the same direction as the normal vector _{n t} of the solder ball mounting surface 234, the angle theta _t of the normal vector _{n t} makes with the x-axis is 90 °. Therefore, when the highest point P _t becomes bright spot, the reflection strength of the solder balls installation surface 234 should be maximal. In other words, the bright spot detected from the solder ball 232 when the reflection intensity of the solder ball installation surface 234 is maximum is the highest point P _t . The light source moving time when the highest point P _t is the bright spot and t _t.

Δθ_{ｔ〜ｒ＋１}は、輝点Ｐ_ｒ＋１における角度θ_ｒ＋１と最高地点Ｐ_ｔにおける角度θ_ｔとの角度の差である。式（１６）により、ある輝点Ｐ_ｒ＋１のピーク時間ｔ_ｒ＋１と、最高地点Ｐ_ｔのピーク時間ｔ_ｔがわかれば、輝点Ｐ_ｒ＋１におけるはんだボール２３２の傾きθ_ｒ＋１の求めることができる。 The equation for obtaining the angle θ _{r + 1} at the bright spot P _{r + 1} is _expressed by the following equation (16) according to the equation (15).

_Δθ t~r _{+ 1} is the difference angle between the angle theta _t at an angle theta _{r + 1} and the highest point _{P t} in the bright spot _{P r + 1.} If the peak time t _{r + 1} of a certain bright spot P _{r + 1 and} the peak time t _t of the highest point P _t are known from the equation (16), the inclination θ _{r + 1} of the solder ball 232 at the bright spot P _{r + 1} can be obtained.

By referring to a plurality of inspection images, specifying the amount of change in the x-coordinate values of P _r and P _{r + 1} as Δx _{r + 1} and substituting equation (16) into equation (14), the bright spot P _{r + 1} and the bright spot P _r Δh _{r + 1} can be obtained from the difference in height between the two. By accumulating the height variation Δh of each bright point can be calculated by equation (17) below the height h _t of the solder balls 232.

  FIG. 11 is a flowchart illustrating a process of inspecting the inclination and the height of the protrusions having a curved shape. The position control unit 122 installs the light source 220 at the start point S at time t = 0, and moves the light source 220 at a constant angular velocity ω (S30). After the elapse of the predetermined time, the imaging unit 112 captures the plurality of solder balls 232 of the BGA 230 and acquires an inspection image (S32). The position of each solder ball 232 in the inspection image may be specified in advance by image processing. The reflection intensity measurement unit 126 refers to the inspection image and detects the bright spot of each solder ball 232. The reflection intensity measuring unit 126 records the coordinates of the bright spot and the light source moving time as reflection intensity information for each solder ball 232 (S34). When a curved surface such as the solder ball 232 is to be inspected, in the reflection intensity information, the coordinates of the bright spot and the light source moving time are associated with each solder ball 232. Also, the reflection intensity of the solder ball installation surface 234 is recorded as a part of the reflection intensity information. If the light source 220 has not reached the end point E (N in S36), the process returns to S32. Until the light source 220 reaches the end point E, imaging of an inspection image (S32) and recording of reflection intensity information (S34) are periodically performed.

  When the light source 220 reaches the end point E (Y in S36), the position control unit 122 stops the light source 220 (S38). The position specifying unit 124 specifies the coordinates of the highest point for each solder ball 232 with reference to the reflection intensity information (S40). More specifically, the bright spot when the reflection intensity of the solder ball installation surface 234 has the highest value is specified as the highest spot. In accordance with the equations (15) and (16), the curved surface inclination calculation unit 132 calculates the inclinations of all bright spots (S42). The altitude calculation unit 136 calculates the amount of height change at all bright spots from these inclinations (S44). The altitude calculation unit 136 calculates the height of all the solder balls 232 (S46).

The altitude calculation unit 136 sets the average value of the heights of the solder balls 232 as a reference value. Then, a relative height that is a difference between the height of the solder ball 232 and the reference value is calculated. Abnormality determining unit 134 determines whether the relative altitude is large solder ball 232 than a predetermined threshold value _{T 2} is present (S48). If present (Y of S48), the abnormality determination unit 134 instructs the warning unit 114 to generate a warning (S50). If it does not exist (N in S48), S50 is skipped.

  The shape inspection apparatus 100 has been described above based on the embodiment. The shape inspection apparatus 100 identifies the light source direction based on the speed at which the light source 220 moves and the light source moving time. Since the maximum reflection position is searched while changing the relative positional relationship among the camera, the light source, and the inspection target object, there is an advantage that there are few restrictions on setting the initial position of the camera, the light source, and the inspection target object.

  In addition, as shown in equations (7) and (16), if the light source movement time is measured, the inclination of the plane or curved surface can be obtained. Measurement processing is possible. In particular, since setting and calculation of parameters such as surface reflection parameters are not necessary, this is advantageous not only from convenience but also from the viewpoint of measurement accuracy. Since the shape of the inspection target object is not determined while being applied to the mathematical model, it is easy to deal with various shapes of the inspection target object.

  The highest point of the solder ball 232 may be set in advance, but even if it is not set, it can be specified based on the reflection intensity of the solder ball installation surface 234. For this reason, it is possible to further improve convenience and measurement accuracy. Further, since the plurality of pins 206, the plurality of solder balls 232, the plurality of SIPs 204, and the plurality of BGAs 230 can be inspected together by moving the light source 220 once, the inspection efficiency is high.

  In the present embodiment, the SIP 204 and the BGA 230 have been described as an object. However, the inspection object is not limited to this, and a wide inspection object can be used as long as it has a certain level of gloss or a flat surface. For example, the present invention can be applied to detection of swelling and dent of a package substrate.

  The present invention has been described based on the embodiments. The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. .

  Various aspects of the invention ascertained from the above embodiments and modifications will be exemplified below, including those already described in the claims. The following inventions are recognized in connection with the method of measuring the inclination of the plane.

A1. By changing one or more positions among an inspection object having a flat part on the outer shape, a light source that irradiates light on the flat part, and a camera that images reflected light from the flat part, the flat part changes to the light source. A position control unit that changes both or one of the light source direction toward the camera and the viewpoint direction from the plane part toward the camera;
A position specifying unit for specifying the light source direction and the viewpoint direction based on the change speed and change time of both or one of the light source direction and the viewpoint direction;
An inclination calculation unit that calculates an inclination of the plane part based on the light source direction and the viewpoint direction when light is reflected from the plane part in the viewpoint direction;
A shape inspection apparatus comprising:

A2. A reflection intensity measuring unit that measures the intensity of the reflected light at the position of the camera;
The inclination calculation unit calculates the inclination of the plane part using the light source direction and the center direction of the viewpoint direction when the intensity of the reflected light is maximized as a normal vector of the plane part. The shape inspection apparatus according to A1.

A3. The inspection object has a plurality of plane portions,
The inclination calculating unit calculates an inclination of each of the plurality of plane parts based on the light source direction and the viewpoint direction when light is reflected from each plane part in the viewpoint direction. The shape inspection apparatus according to A2.

  A4. The shape inspection apparatus according to A3, further comprising: a warning unit that generates a warning when an inclination that deviates by a predetermined amount or more from a predetermined reference value is detected for any of the flat surfaces.

  A5. The shape inspection apparatus according to A4, wherein the warning unit uses an average value of inclinations of the plurality of plane portions as the reference value.

  A6. The shape inspection apparatus according to any one of A1 to A5, wherein the object to be inspected is a pin insertion type IC (Integrated Circuit), and the planar portion is a pin.

A7. By changing one or more positions among an inspection object having a flat part on the outer shape, a light source that irradiates light on the flat part, and a camera that images reflected light from the flat part, the flat part changes to the light source. A function of changing both or one of the light source direction toward and the viewpoint direction from the plane portion toward the camera;
A function of specifying the light source direction and the viewpoint direction based on a change speed and a change time of both or one of the light source direction and the viewpoint direction;
A function of calculating the inclination of the plane part based on the light source direction and the viewpoint direction when light is reflected from the plane part in the viewpoint direction;
A shape inspection program characterized by causing a computer to exhibit this.

DESCRIPTION OF SYMBOLS 100 Shape inspection apparatus 110 UI part 112 Imaging part 114 Warning part 120 Data processing part 122 Position control part 124 Position specification part 126 Reflection intensity measurement part 128 Inclination calculation part 130 Plane inclination calculation part 132 Curved surface inclination calculation part 134 Abnormality determination part 136 Altitude Calculation unit 140 Data holding unit 142 Image holding unit 144 Reflection intensity information holding unit 200 Inspection target surface 202 Inclination reference surface 204 SIP
206 pins 220 light source 222 camera 230 BGA
232 Solder ball 234 Solder ball installation surface

Claims (6)

By changing one or more positions of the object to be inspected having a curved protrusion on the outer shape, a light source that irradiates light to the protrusion, and a camera that images reflected light from the protrusion, A position control unit that changes both or one of a light source direction toward the light source and a viewpoint direction from the protrusion toward the camera;
Each time both or one of the light source direction and the viewpoint direction is changed, a point that reflects light in the viewpoint direction on the projection is specified as a bright spot, and the light source direction and the light source when the bright spot is specified and An inclination calculating unit for calculating an inclination at the bright spot of the protrusion based on a viewpoint direction;
An altitude calculation unit for calculating the height of the protrusion from the inclination of the plurality of bright spots of the protrusion,
Equipped with a,
A reference plane parallel to the tangent plane at the highest point of the protrusion is set in advance,
The altitude calculation unit identifies a bright spot that reflects light in the viewpoint direction from the protrusion when the reference surface reflects light in the viewpoint direction, and determines a high point at the highest point. The shape inspection apparatus calculates the height as the height of the protrusion. The altitude calculation unit assumes that the inclination of the protrusion at the highest point is the same as the inclination of the surface on which the protrusion is installed in the inspection object, and the surface on which the protrusion is installed is the reference The shape inspection apparatus according to claim 1, wherein a height from the reference surface to the highest point of the protrusion is calculated as the height of the protrusion. The inspection object has a plurality of protrusions,
Wherein the tilt calculation unit, each time changing either or both of the light source direction and the view direction, which identifies bright spots for each of the plurality of protrusions, and calculates the slope at each bright spot Item 3. The shape inspection apparatus according to Item 1 or 2 . The shape inspection apparatus according to claim 3, further comprising: a warning unit that generates a warning when a height that deviates a predetermined amount or more from a predetermined reference value is detected for any one of the protrusions. 5. The inspection object is an IC (Integrated Circuit) in which solder ball elements are arranged in a plane, and the protrusion is a solder ball element. 6. Shape inspection device. By changing one or more positions of the object to be inspected having a curved protrusion on the outer shape, a light source that irradiates light to the protrusion, and a camera that images reflected light from the protrusion, A function of changing both or one of the light source direction toward the light source and the viewpoint direction from the protrusion toward the camera;
Each time both or one of the light source direction and the viewpoint direction is changed, a point that reflects light in the viewpoint direction on the projection is specified as a bright spot, and the light source direction and the light source when the bright spot is specified and A function of calculating an inclination at the bright spot of the protrusion based on a viewpoint direction;
When the reference plane parallel to the tangential plane at the highest point of the protrusion part reflects light in the viewpoint direction, the bright spot that reflects light in the viewpoint direction from the protrusion part is specified as the highest point of the protrusion part, A function of calculating the height at the highest point as the height of the protrusion;
A shape inspection program characterized by causing a computer to exhibit this.

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