JP4557471B2 - Method and apparatus for testing flatness of semiconductor device package - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device mounting body in which a plurality of ball terminals are arranged in one plane, such as a package such as a BGA (Ball Grit Array) or a CSP (Chip Size Package) (in this specification, “semiconductor package”). The present invention also relates to a method and an apparatus for inspecting the flatness of a ball terminal of a “package”.
[0002]
[Prior art]
In a semiconductor package such as BGA or CSP in which a plurality of ball terminals are arranged in one plane, the tip of the formed ball terminal must be within a plane parallel to one plane of the semiconductor package with a specified accuracy. I must.
However, it is difficult with the current technology to keep the flatness so that the apex positions of the ball terminals of BGA and CSP are within one plane, and it is difficult to manufacture the ball terminals with the flatness kept uniform. Even if it is possible, the flatness of the ball terminal apex position may deteriorate due to thermal stress or external stress acting in the subsequent process.
[0003]
Therefore, for the BGA and CSP, the flatness of the ball terminal apex position is measured using an inspection device such as a laser displacement measuring device or an image processing measuring device before the mounting process. When the flatness is low, there is a possibility that a mounting failure may occur when the semiconductor package is mounted on the substrate, and those whose flatness is below the specified value are discarded.
[0004]
The flatness is generally measured by a virtual plane method using a read scanner. There, the height of each tip is obtained for all ball terminals, and the virtual plane is obtained from the coordinates of those heights using the triangulation method or the least square method. However, the positional deviation or deformation (warpage) of the resin of the semiconductor package itself that is the measurement target is not considered. Therefore, the virtual plane obtained only from the height of the ball terminal may not correspond to the plane on which the semiconductor package is actually mounted.
[0005]
If the measurement target is an ideal semiconductor package, the conventional virtual plane and the actual mounting surface correspond to each other, so that accurate flatness can be measured. However, since it is impossible to produce only an ideal semiconductor package with the current assembly technology, there is still room for improvement in the flatness measurement by the virtual plane method. When the flatness measurement is inaccurate, there is a risk that a defective product will be mistakenly marketed as a non-defective product, resulting in a problem that quality assurance cannot be sufficiently performed.
[0006]
As a method for inspecting the flatness of the flatness of the virtual package, it is not a semiconductor package with ball terminals. Based on the height of these leads and the lead height, it is assumed that the semiconductor package has been naturally dropped on the virtual plane. Has been proposed (see Japanese Patent No. 690675).
[0007]
However, the proposed method does not take into account the resin displacement and deformation of the semiconductor package, and the center of gravity is determined based on the ideal semiconductor package. Is different from the state in which it is placed on a horizontal plane, and an error occurs in the measurement of flatness.
[0008]
[Problems to be solved by the invention]
Regardless of the deformation of the package, if you want to measure the flatness accurately, you can measure the flatness of the terminal with the semiconductor package placed on the actual plane. Since they are arranged, the height of the ball terminal cannot be measured in a state where the ball terminal is placed on a real plane so that the ball terminal faces downward.
Accordingly, an object of the present invention is to enable accurate flatness measurement by taking into account the virtual plane method and the posture when the semiconductor package is placed on the real plane.
[0009]
[Means for Solving the Problems]
The flatness inspection method of the present invention is a method for inspecting the ball terminal flatness of a semiconductor package having a plurality of ball terminals on one surface, and includes the following steps (A) to (E).
(A) An attitude measurement step for placing the semiconductor package on a flat stage with the surface having the ball terminal facing down, and obtaining the attitude of the semiconductor package;
(B) a ball measurement step for obtaining a coordinate position of each ball terminal tip in a state where the semiconductor package is floated in the air;
(C) obtaining a virtual plane in contact with some of the ball terminal tips from the attitude of the semiconductor package obtained in the posture measurement step and the coordinate position of each ball terminal tip obtained in the ball measurement step;
(D) calculating the flatness of the ball terminal from the determined virtual plane and the coordinate position of each ball terminal tip determined in the ball measurement step;
(E) A step of comparing the obtained flatness with a standard value to determine pass / fail.
[0010]
The flatness inspection apparatus of the present invention is an apparatus for inspecting the flatness of a ball terminal of a semiconductor package having a plurality of ball terminals on one surface. As shown in FIG. 1, a surface having ball terminals on a flat stage. The attitude measurement unit 2 that optically measures the attitude of the semiconductor package placed with the face down, the storage device 4 that stores the attitude of the semiconductor package obtained by the attitude measurement unit 2, and the semiconductor package floating in the air The ball measurement unit 6 that obtains the coordinate position of each ball terminal tip in a state, the ball from the attitude of the semiconductor package stored in the storage device 4 and the coordinate position of each ball terminal tip of the semiconductor package obtained by the ball measurement unit 6 Obtain a virtual plane that contacts some of the terminal tips, and determine the flatness of the ball terminal from the virtual plane and the coordinate position of each ball terminal tip of the semiconductor package. A data processing device 8 for comparing the flatness with a standard value to determine pass / failure, and taking out the semiconductor package from the storage container and positioning it on the posture measuring unit 2 and the ball measuring unit 6, and predetermining the semiconductor package after completion of the inspection And a transporting mechanism for storing in the place.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the flatness inspection method of the present invention, the posture measurement step, as an example, performs imaging from the four directions of the front, rear, left, and right, and obtains an overall tilt or a partial tilt as the posture of the semiconductor package.
[0012]
In the flatness inspection apparatus according to the present invention, the attitude measurement unit 2 includes, for example, an imaging mechanism in the front, rear, left, and right sides of a planar stage on which a semiconductor package is placed, and a semiconductor is obtained from image data captured by the imaging mechanism. One or both of the overall inclination and the partial inclination of the package are extracted as the attitude of the semiconductor package.
[0013]
An example of the imaging mechanism is four electronic cameras that are arranged on four sides of the planar stage in the front, rear, left, and right directions and are directed to the semiconductor package placed on the planar stage.
[0014]
Another example of the imaging mechanism includes four reflecting mirrors arranged at an angle with respect to the semiconductor package placed on the planar stage at four sides of the planar stage in the front, rear, left, and right directions, and each reflecting mirror. And an electronic camera movably mounted so as to image the semiconductor package on the planar stage.
[0015]
【Example】
FIG. 2 is a schematic plan view showing the first embodiment, and FIG. 3 is a schematic front view thereof. Reference numeral 10 denotes a P & P (pick and place) unit of the transport mechanism, which includes a rail 11 for guiding the hand 12, a hand 12 movable along the rail 11, and a transport lane (not shown) for transporting the tray. ing. The hand 12 can move up and down, and the semiconductor package 14 can be held or separated by suction or chucking at the tip. For the sake of explanation, the hand 12 is shown at each stop position, but the number of hands 12 may be one or plural.
[0016]
A plurality of semiconductor packages are transferred in a state of being accommodated in the tray, transferred from the tray to the posture measuring unit 2 and the ball measuring unit 6, and returned to the tray again after the measurement in each unit is completed.
A loader (not shown) is provided at one end of the P & P unit 10, and the loader cuts out the trays in the stocker 16 one by one and arranges them at a position 18 on the transport lane.
[0017]
A posture measuring unit 2 and a ball measuring unit 6 are arranged in this order from one end along the P & P unit 10. The attitude measurement unit 2 includes a planar stage 20, electronic cameras 22-1 to 22-4, and an illumination device (not shown).
The flat stage 20 is disposed below the rails of the P & P unit 10, and its surface is satin-finished and kept in a completely horizontal state. The electronic cameras 22-1 to 22-4 such as CCD cameras are arranged on the side of the front / rear / left / right directions of the flat stage 20, and are placed on the flat stage 20 with the ball terminals facing downward. Is directed in the direction in which the image can be taken from the side. The illumination device can illuminate the semiconductor package 14 placed near the electronic cameras 22-1 to 22-4 from the side in four directions, front, rear, left and right of the planar stage 20, from the side. Yes.
[0018]
An inspection camera 30 is disposed in the ball measuring unit 6 in order to measure the height of the ball terminal on the lower surface of the semiconductor package 14 held by the hand 14 of the P & P unit 10. The inspection camera 30 may be a measurement unit using a laser displacement measurement method, or may be an image processing measurement device including an imaging mechanism such as a CCD camera. In the case of a measuring unit using a laser displacement measuring method, the inspection camera 30 includes a laser head composed of a semiconductor laser irradiation unit and a laser displacement meter. In this embodiment, it is assumed that the ball measurement unit 6 includes a measurement unit using a laser displacement measurement method.
[0019]
An unloader portion is provided on the other end side of the P & P unit 10. In the unloader unit, the semiconductor package determined as a non-defective product or a defective product based on the inspection result is stored in each tray by the P & P unit 10. 34 is a non-defective product tray, and 36 is a defective product tray. The tray storing the predetermined number of semiconductor packages is transferred to the stockers 40 and 42 by the unloader unit.
[0020]
Next, the operation of this embodiment will be described with reference to FIGS. FIG. 4 is a flowchart showing a series of operations, and FIG. 5 shows image data captured by the attitude measurement unit 2.
[0021]
The loader section automatically cuts out trays containing unmeasured semiconductor packages one by one from the stocker 16. The cut out tray 18 is sent in the direction of the planar stage 20 of the posture measuring unit 2 through the conveyance lane. When the tray 18 is conveyed to the side of the planar stage 20, the hand 12 of the P & P unit 10 takes out one semiconductor package (abbreviated as IC in FIG. 4) 14 from the tray 18 and places it on the planar stage 20. At this time, the semiconductor package 14 is placed so that the surface with the ball terminals faces downward and the center of the semiconductor package 14 is at the center of the planar stage 20.
[0022]
When the semiconductor package 14 is placed on the planar stage 20, lighting devices (not shown) installed in the four directions of front, rear, left and right next to the stage are turned on, and illumination is performed from the four lateral directions of the semiconductor package 14 on the planar stage 20. Hit it. Simultaneously with the illumination, the electronic cameras 22-1 to 22-4 capture an image of the semiconductor package 14 on the planar stage 20 as image data.
[0023]
The imaging data is captured as image data from four directions as shown in FIG. 5, for example. The captured image is binarized and converted as an A-side image, a B-side image, a C-side image, and a D-side image for each side, and a plurality of locations at the upper part of the package part are searched and captured. Determine the coordinate values. For example, the inclination is obtained as a difference in height between both ends of the upper part of the package portion. This is performed on four sides, and the four tilt data are connected to obtain a plane having a tilt. Further, the deformation amount can be obtained from the height between the center point and both ends, or the difference in height in a shorter section can be obtained as the deformation amount. The plane data calculated here is temporarily stored in the storage device 4 together with the tray address data as data specific to the semiconductor package.
[0024]
When the measurement by the posture measuring unit 2 is completed, the semiconductor package 14 is returned from the planar stage 20 to the tray 18 by the hand 12, and the hand 12 places the next semiconductor package 12 in the tray 18 on the planar stage 20. When the posture measurement of all the semiconductor packages 14 in the tray 18 is completed by repeating this, the tray 18 is transported to the side of the ball measuring unit 6 by the transport lane. In the ball measuring unit 6, the semiconductor package 14 is stopped just above the laser head by the hand 12 of the P & P unit 10. Based on the semiconductor package information inputted in advance, the laser head scans the semiconductor package 14 so as to capture the X / Y / Z axis coordinates of all balls and the X / Y coordinates on the semiconductor package 14 from directly under the semiconductor package 14. To do. Each coordinate position obtained by laser scanning is stored in the temporary storage device 4.
[0025]
Here, the orientation data (inclination data or deformation data) of the semiconductor package 14 previously measured is called from the storage device 4, and the semiconductor package 14 is displayed on the plane from the data and the ball position data in the ball measuring unit 6. Calculate the virtual plane that touches the ball terminal when placed on.
[0026]
The virtual plane calculation method is performed, for example, as follows. The virtual plane is obtained from the ball position data of the semiconductor package 14 for which the virtual plane is to be obtained by using the triangulation method or the least square method as in the prior art. The coordinates are subtracted between the virtual plane and the attitude data, and the virtual plane is corrected based on the attitude data.
[0027]
Thereafter, the flatness is calculated using the distance between the calculated and corrected virtual plane and the coordinate data of the top of the ball terminal as coplanarity data. The calculated data is compared with a standard value set in advance by the user to determine whether the data is within the standard or not, and a non-defective product / defective product is determined. The calculated coordinate data and good / defective product data are stored in the storage device 4.
This operation is repeated to inspect all the semiconductor packages 14 in the tray.
[0028]
When all the semiconductor packages 14 have been inspected, the tray is sent to the unloader unit, the non-defective semiconductor package is transferred to the non-defective product tray, and the defective semiconductor package is transferred to the non-defective product tray with the hand 12 of the P & P unit 10. By repeating this for a plurality of trays, a continuous inspection of a large number of semiconductor packages 14 is performed.
[0029]
6 and 7 show the second embodiment. FIGS. 6 and 7 correspond to FIGS. 2 and 3 of the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted.
In this embodiment, the configuration of the posture measurement unit 2 is different from that of the first embodiment. In the posture measurement unit 2, mirrors 50-1 to 50-4 that are directed downward at an angle of 135 degrees with respect to the center are attached to the left and right and front and rear sides of the planar stage 20. The space just below is hollow. A CCD camera 52 and an illumination device 54 are attached below the planar stage 20. The CCD camera 52 is movably mounted so as to be sequentially moved to positions below the respective mirrors 50-1 to 50-4, and the respective positions are passed through the respective mirrors 50-1 to 50-4. Thus, the image of the semiconductor package 14 can be captured.
[0030]
In the attitude measurement unit 2, when the semiconductor package 14 is placed on the planar stage 20, the illumination device 54 is turned on, and is reflected by the mirrors 50-1 to 50-4 to illuminate the semiconductor package 14 from four directions. Then, the CCD camera 52 sequentially captures four-direction images of the semiconductor package 14 projected onto the mirrors 50-1 to 50-4 as image data through the mirrors 50-1 to 50-4. The captured image is processed in the same manner as in the first embodiment.
[0031]
When the attitude measuring unit 2 obtains the overall inclination as the attitude of the semiconductor package 14, the virtual plane is an inclined plane. Further, when the partial inclination, that is, the deformation amount is obtained as the attitude of the semiconductor package 14, the virtual plane is a combination of partial planes having different inclinations.
[0032]
【The invention's effect】
According to the first aspect of the present invention, a virtual plane is obtained based on the attitude that the semiconductor package is actually placed on the planar stage and the coordinate position of each ball terminal tip, and the virtual plane and the coordinate position of each ball terminal tip are Therefore, the flatness of the ball terminal can be obtained more accurately.
According to the second aspect of the present invention, since the overall inclination or the partial inclination is obtained as the attitude of the semiconductor package, it is easy to reflect it on the virtual plane.
According to the invention of claim 3, such accurate flatness measurement can be automatically performed.
In the invention of claim 4, since the imaging mechanism is provided on the side of the planar stage in the front, rear, left and right directions, the image data of the semiconductor package can be taken from the four directions, and the attitude of the semiconductor package can be read correctly. .
According to the invention of claim 5, since the four electronic cameras are arranged on the side of the front / rear / left / right directions of the plane stage as the imaging mechanism, image data can be taken in simultaneously from the four directions, and high-speed processing is performed. Is possible.
According to the invention of claim 6, since one movable electronic camera is used as the imaging mechanism, the apparatus can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a flatness inspection apparatus according to the present invention.
FIG. 2 is a schematic plan view showing a first embodiment of a flatness inspection apparatus.
FIG. 3 is a schematic front view of the same embodiment.
FIG. 4 is a flowchart showing the operation of the embodiment.
FIG. 5 is a diagram illustrating image data captured by an attitude measurement unit in the embodiment.
FIG. 6 is a schematic plan view showing a second embodiment of the flatness inspection apparatus.
FIG. 7 is a schematic front view of the same embodiment.
[Explanation of symbols]
2 Attitude measurement unit 4 Storage device 6 Ball measurement unit 8 Data processing device 10 P & P unit 12 Hand 12
14 Semiconductor Package 20 Planar Stage 22-1 to 22-4, 52 Electronic Camera 30 Inspection Camera

Claims (4)

A method for inspecting the flatness of a ball terminal of a semiconductor device mounting body having a plurality of ball terminals on one surface, comprising the following steps (A) to (E):
(A) The semiconductor device mounting body is placed on a flat stage with its ball terminal facing down, and in order to determine the posture of the semiconductor device mounting body , imaging is performed from four directions, front, rear, left, and right. Attitude measurement step for obtaining an overall inclination or a partial inclination as the attitude of the device mounting body ,
(B) a ball measurement step for obtaining a coordinate position of each ball terminal tip in a state where the semiconductor device mounting body is floated in the air;
(C) obtaining a virtual plane in contact with some of the ball terminal tips from the posture of the semiconductor device mounting body obtained in the posture measurement step and the coordinate position of each ball terminal tip obtained in the ball measurement step;
(D) calculating the flatness of the ball terminal from the determined virtual plane and the coordinate position of each ball terminal tip determined in the ball measurement step;
(E) A step of comparing the obtained flatness with a standard value to determine pass / fail. In a flatness inspection apparatus for inspecting the flatness of a ball terminal of a semiconductor device mounting body having a plurality of ball terminals on one surface,
An attitude measurement unit that optically measures the attitude of the semiconductor device mounting body placed on a planar stage with a surface having a ball terminal facing down , wherein an imaging mechanism is provided laterally in the front, rear, left, and right directions of the planar stage. An attitude measurement unit that extracts one or both of the overall inclination and the partial inclination of the semiconductor device mounting body as the attitude of the semiconductor device mounting body from image data captured by the imaging mechanism ,
A storage device for storing the posture of the semiconductor device mounting body obtained by the posture measurement unit;
A ball measuring unit for obtaining a coordinate position of each ball terminal tip in a state where the semiconductor device mounting body is floated in the air;
A virtual plane in contact with some of the ball terminal tips is obtained from the posture of the semiconductor device package stored in the memory and the coordinate position of each ball terminal tip of the semiconductor device package obtained by the ball measurement unit, and the virtual plane is obtained. A data processing device for determining the flatness of the ball terminal from the plane and the coordinate position of each ball terminal tip of the semiconductor device mounting body, and comparing the flatness with a standard value to determine pass / failure,
A semiconductor device mounting body is taken out from a storage container and positioned on the posture measuring unit and the ball measuring unit, and a transport mechanism for storing the semiconductor device mounting body after completion of inspection in a predetermined place is provided. Flatness inspection device. 3. The flatness according to claim 2 , wherein the imaging mechanism is four electronic cameras disposed on four sides of the planar stage in front, rear, left, and right directions and directed to a semiconductor device mounting body mounted on the planar stage. Inspection device. The imaging mechanism has four reflecting mirrors disposed on the side of the planar stage in the front, back, left, and right directions in an inclined manner with respect to the semiconductor device mounting body placed on the planar stage;
The flatness inspection apparatus according to claim 2 , further comprising: one electronic camera movably attached so as to image the semiconductor device mounting body on the planar stage via the reflecting mirrors.

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