JP2011214946A - Plating inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plating inspection apparatus for performing a stable inspection by managing a trend of plating quality in a plating manufacturing process.SOLUTION: The plating inspection apparatus includes: an illumination means of irradiating a plate-like metal product with illumination light; an imaging means of obtaining image information by imaging the plate-like metal product; a conveying means of moving the plate-like metal product in one direction at a fixed speed; a supply/discharge unit for supplying and discharging the plate-like metal products onto the conveying means one by one; a processing control unit for obtaining inspection information by processing image information of a plating reference article, determining a plated state and obtaining an inspection result by comparing the inspection information with image information of the plate-like metal product, and performing operation control of the entire device; a storage means of storing the image information and inspection result of the plate-like metal product and the image information and inspection information of the plating reference article; and a state managing means of comparing the inspection result of the plate-like metal product with a trend of the image information by referring to the image information of the plating reference article.

Description

  The present invention relates to a plating inspection apparatus using image data of a plate-like metal surface obtained by an optimum imaging means corresponding to a plating method.

  Some plate-shaped metal products are partially plated and taped. For example, a lead frame which is a base material of a semiconductor package corresponds to this. Hereinafter, this lead frame will be described as an example. Currently, semiconductor packages using lead frames are required to have strict quality assurance for lead frames as base materials due to the expansion of applications. Generally, iron nickel alloy (42 materials), copper alloy, etc. are used as the base material of the lead frame, and the manufacturing method is a stamping method in which metal is mechanically punched using an ultra-precision mold, and the metal is corroded chemically. There is an etching method for forming a pattern.

  In recent years, the packaging technology in the semiconductor technology field is becoming narrower with higher integration and higher functionality of semiconductor devices, and lead frames used in these packages are also becoming more multi-pin and narrower. . In addition, with the increase in the speed of semiconductor elements, the use of metal materials having high electrical conductivity is increasing year by year.

  Conventionally, the inner lead of the lead frame is designed to extend so as to spread radially with the center of the die pad as a reference. In a semiconductor device using a lead frame, an IC chip is fixed to a die pad, and an electrode pad of the IC chip and a bonding portion at the tip of the inner lead are electrically connected by wire bonding or the like. As IC chips become more multifunctional, the number of electrode pads increases, and with the miniaturization of IC chips, the spacing between electrode pads is becoming narrower. Along with this, the number of lead portions of the lead frame to be connected to the electrode pads is increased, the number of leads is increased, and the pitch between leads and the lead width are various.

The patterned lead frame is subjected to silver plating at a predetermined position such as the inner lead tip. This plating part is used as a bonding part.
Leads with a narrow pitch and lead width between the leads are weak in strength, and the lead is deformed even by a slight external force. This has led to the manufacture of lead frames with protective tape applied to prevent contact between the inner leads and the suspension leads that support the die pad and the inner leads, electrical shorts, deformation of the inner leads, etc. .
Further, after the down-press process, there is also a process in which a tip cut process for cutting the tip of the inner lead is performed.

FIG. 1 shows an outline of the lead frame 10. FIG. 1A shows the lead frame 10 when observed from the front surface side, and FIG. 1B shows the lead frame when observed from the back surface side.
A lead frame 10 manufactured by an etching method or the like has a die pad 1, an inner lead 2, an outer lead 3, a dam bar 4, and a frame portion 5, and a portion where no wiring pattern is formed is defined as a space portion 9. Thereafter, plating 6 is applied to the inner lead 2 in order to reduce the connection resistance between the semiconductor element and the bonding portion. Further, a protective tape 7 is attached to prevent contact between the inner leads and the suspension leads supporting the die pad and the inner leads, electrical short circuit, and deformation of the inner leads. In consideration of the fact that the protective tape 7 is an insulator, polyimide tape is used. Further, a step is formed on the suspension lead 8 by down-pressing, taking into consideration the loading of semiconductor elements on the die pad 1, the inner lead tip cutting for removing the conduction at the tip of the inner lead 2 is performed, and the lead frame is completed. Note that the actual lead frame is in a state in which the above-described wiring patterns are multifaceted.

  As described above, the defect items in the lead frame final inspection include pattern defects (open / short / foreign matter, etc.), lead deformation, tape defects (existence / position misalignment / width defect, etc.), plating defects (existence / non-attachment / attachment). Discrimination of products using automatic inspection machines is indispensable. However, it is difficult to inspect all defects with a single inspection machine. Recently, the demand for inspection on tapes and plating has increased further, and the quality of partial plating applied to bonding parts that connect with IC chips is increasing. Is particularly important, and for example, Patent Document 1 has been proposed as a method of imaging a plating portion with a CCD camera or the like and inspecting the plating state using image processing.

JP 2000-171402 A

  Although it is possible to obtain the difference in contrast between the plate-like metal surface and the plated portion by the technique of Patent Document 1, strictly speaking, the plating state including the side tapered portion of the wiring pattern having a three-dimensional shape is good. An inspection method for judging badness is desirable, and an imaging and inspection method capable of clearly separating the contrast between the metal surface and the plated portion and simultaneously improving the quality of the metal surface as well as the plated portion is desirable. In addition, when microscopic observations are made on the surface of a metal plate or plated surface, there are rolling flaws and irregularities caused by the metal material manufacturing method, and minute brightness and darkness due to these irregularities occurs on the image, depending on the threshold setting in image processing, overdetection It becomes an element, and stable automatic judgment is difficult.

  Therefore, as a method for clearly separating the contrast between the metal surface and the plated portion, a means for imaging the surface of the substrate at an imaging angle of 0 ° to 10 °, and reflection between the metal material of the non-plated portion and the plated material of the plated portion We propose a method for inspecting the surface of a metal substrate by using a light source unit having a wavelength range that maximizes the difference in intensity and an irradiation unit that emits indirect light having a solid angle of 2π. Simultaneous imaging and inspection can be performed, and an inexpensive apparatus can be realized as compared with individual imaging and inspection of a plated portion and a non-plated portion.

  Recently, however, it has been found that the surface state and composition of the plated part change due to slight fluctuations in manufacturing conditions, and the inspection by contrast separation from the metal surface is rarely stabilized. In addition, it is also true that there are varieties with different plating finishes, such as semi-gloss and matte, depending on the presence or absence of the brightening material in the manufacturing process, and it has become necessary to manage the trend of such finishes early with numerical data. .

  Then, this invention is providing the metal-plating test | inspection apparatus which eliminates the above-mentioned subject and performs stable metal-plating test | inspection by carrying out the trend management of the metal-plating quality in a metal-plating manufacturing process.

As means for solving the above problems, the invention according to claim 1 is an inspection apparatus for inspecting defects in plating quality of a plate-shaped metal product, and illuminating means for irradiating the plate-shaped metal product with illumination light When,
Imaging means for obtaining image information by imaging a plate-shaped metal product illuminated by the illumination means;
Conveying means for moving the plate-shaped metal product in one direction at a constant speed;
A supply / discharge section for supplying and discharging the plate-like metal products one by one on the conveying means;
Process the image information of the plating standard product of the plate metal product to obtain inspection information, and compare the inspection information with the image information of the plate metal product to determine the quality of the plating state of the plate metal product A process control unit that obtains the inspection result and controls the operation of the entire apparatus;
Storage means for storing image information and inspection results of the plate-shaped metal product, and image information and inspection information of a plating reference product,
With reference to the image information of the plating standard product, the plating state management means for comparing the inspection result of the metal plate product and the tendency of the image information,
A plating inspection apparatus comprising:

  The invention according to claim 2 of the present invention is the plating inspection apparatus according to claim 1, wherein the plate-shaped metal product is a lead frame.

  The invention according to claim 3 of the present invention is characterized in that the imaging means images the plate-shaped metal product that has reached the imaging position of the imaging means while synchronizing with the transport means. 2. The plating inspection apparatus according to 2.

  Further, the invention according to claim 4 of the present invention feeds back a comparison result obtained by a tendency comparison with a plating reference product to the manufacturing process. Device.

  The plating inspection apparatus according to the present invention is an inspection apparatus that inspects plating quality using image information obtained by an imaging unit corresponding to a plating method. Previously, the surface condition and composition changed due to slight fluctuations in the manufacturing conditions of the plating part, and it was extremely rare that the inspection by contrast separation from the metal surface did not stabilize, but the plating inspection according to the present invention According to the apparatus, stable plating inspection can be performed.

Diagram showing the outline of the lead frame External view showing an example of a plating inspection apparatus according to the present invention The figure which showed the illumination part of the plating inspection apparatus which concerns on this invention in detail Schematic diagram showing an example of a lead frame inspected by a plating inspection apparatus according to the present invention Schematic diagram showing the outline of the inner lead, plating part, and space part The flowchart which showed the whole operation | movement of the image processing and defect determination processing of the plating inspection apparatus which concerns on this invention (A) The division | segmentation matching process of the plating inspection apparatus which concerns on this invention is shown, (b) The figure which shows the detection of plating adhesion (A) The figure which shows the area shift detection by the plating test | inspection apparatus based on this invention (b) The figure which shows the area shift detection in case plating is performed in the middle of the inner lead (c) The figure which shows another area shift detection The figure which shows an example which calculated | required the histogram peak average brightness | luminance from the reference | standard workpiece | work and inspection work of the same kind by the plating inspection apparatus which concerns on this invention The figure which showed the example of an inspection result display by the plating inspection apparatus which concerns on this invention

  Hereinafter, an embodiment of a plating inspection apparatus according to the present invention will be described with reference to the drawings.

FIG. 2 is an external view showing an example of a plating inspection apparatus according to the present invention. 2A is a view seen from the front, and FIG. 2B is a view seen from the side. The plating inspection apparatus of the present invention includes an illuminating unit 30 that is an illuminating unit that illuminates the plate-shaped metal product 10, an imaging camera 40 that is an imaging unit that images the surface of the illuminated plate-shaped metal product 10, and a plate-shaped metal. A transport unit 20 that is a transport unit that moves the product 10 in a constant direction at a constant speed is provided. The imaging camera 40 is synchronized with the transport unit 20 and images the surface of the plate-shaped metal product that has reached the inspection position. The processing control unit 60 inspects plating defects existing on the plate-like metal surface using image information obtained by imaging the plate-like metal surface with the imaging camera 40, obtains the inspection result, and is plated. The image of the plating state is compared between the inspection image in the region and the image information of the plating reference product. Further, the processing control unit 60 controls the illumination unit, the imaging camera, the transport unit, the supply / discharge unit. Although not shown, a supply / discharge unit for supplying and discharging the plate-like metal products one by one is provided on the transport unit. 21 is a transport means operation start button. In this embodiment, the operation of supplying and discharging the plate-shaped metal product (lead frame) 10 to the conveying means 20 is illustrated assuming that it is manually placed.

  In addition, image information and inspection results of the plate-shaped metal product, and image information and inspection information (described later) of a plating reference product (described later) are stored in a storage unit which is a storage unit (not illustrated).

  FIG. 3 is a diagram showing the illumination unit 30 in detail. The illumination unit 30 includes both a dome illumination 42 that emits indirect light and a direct illumination 41 that emits direct light. The dome illumination 42 is effective for plating inspection in a state where the surface of the plated portion is highly flat, that is, a surface state that can be expressed as glossy or semi-glossy, and has the largest difference in reflection intensity depending on the metal plate material used and the plating material. The plate-shaped metal material and the plating material are optically separated by utilizing the wavelength range of 400 nm to 600 nm. The direct illumination 41 uses the same wavelength region, and is effective for plating inspection in a state where the flatness of the surface of the plated portion is low, that is, a state where it can be expressed as matte, and by irradiating direct light in an irradiation range of 20 to 60 °. , High contrast extraction of the plating part. Note that the dome illumination 42 and the direct illumination 41 are not used at the same time, and an image desired by the user is appropriately selected according to plating manufacturing conditions. The elevation angle θ of the imaging means indicates the angle formed by the vertical direction of the plate-shaped metal product and the optical axis, and the elevation angle θ is preferably around 5 °. The reason why the elevation angle θ is not 0 ° is that fine irregularities such as rolling flaws on the surface of the plate-like metal are reduced at the time of imaging to aim at prevention of erroneous detection and overdetection. Then, the imaging opening at the top of the illumination is formed at a predetermined position according to the elevation angle θ. The imaging camera can be selected from a line camera, an area camera, monochrome, and color according to the application, and in this example, a mode in which a line camera is used is illustrated.

  FIG. 4 is a schematic diagram showing an example of a lead frame inspected by the plating inspection apparatus according to the present invention. 101 is a lead frame, 11 is a die pad, 12 is an inner lead, 13 is an outer lead, 14 is a dam bar, 15 is a frame portion, 16 is plating, 17 is a protective tape, 18 is a lead, and 19 is a space portion.

  FIG. 5A is a schematic diagram showing an outline of the inner lead 12, the plating part 16, and the space part 19, and FIG. 5B shows a profile on the line L1 in FIG. The horizontal axis indicates the position, and the vertical axis indicates the density of the reflected light as a gradation value. As described above, the density information is separated in each of the inner lead 12, the plating 16, and the space portion 19, so that only the plated portion can be extracted and image processing can be easily performed. For example, the back side of the lead frame is not plated, but there is a possibility that plating wraps around (attaches to) the back side of the lead frame, so if you want to inspect the back side, switch between manual and automatic lead frames. It is possible to perform the same inspection by inverting the front and back.

  The processing control unit 60 controls the illumination unit, the imaging camera, the transport unit, the supply unit, and the discharge unit and uses the image information obtained by imaging the plate-shaped metal surface to cause plating defects existing on the plate-shaped metal surface. To extract. Further, an image comparison of the plating state with the plating standard product in the plated area is performed. FIG. 6 is a flowchart showing the overall operation of this image processing / defect determination processing. The timing at which the imaging unit captures an image is obtained by synchronizing with the transport speed of the transport unit that moves the plate-shaped metal product in one direction at a constant speed to obtain image information (step S1). This image information is sent to the processing control unit, and information on each part of the plating unit is extracted from this image information (step S2). Further, defect detection / determination processing is executed using the extracted information (step S3). This defect detection / determination process is performed on a predetermined plating area formed on the plate-shaped metal product, and then the entire operation is completed (in the case of YES in step S4). If NO in step S4, the process further proceeds to step S1.

  The process for plating inspection will be described. First, one of the lead frames is used as a plating reference product, and the image information is picked up by the imaging means to obtain image information (master image) of the plating reference product. A binarization process for extracting only the plating part is performed with respect to the image information of the standard plating product, and further, an expansion / contraction process for the binary image is performed as many times as necessary (the number of steps). After suppressing rattling, this image is newly used as inspection information for plating inspection. Then, after performing a position correction process using a reference position set in advance between the inspection information and the captured image, by performing a division matching process after appropriately setting the matching area 70 in the plating portion, Plating defects such as plating residue, plating non-adherence, etc. are detected (FIG. 7A). On the other hand, the plating adhesion refers to a defect in which plating is attached to a portion that should not be attached, and whether or not there is a luminance value portion higher than the binarization level for the plating area in order to detect this failure. This is possible to determine (FIG. 7B).

  Next, the plating area deviation detection is performed as follows. The distance between the center of the lead frame island 1 and the plating end in the four directions on the master image is determined in advance. Using this distance as a reference value, the same processing is performed each time on the image information of the imaged inspection work, and the obtained distance between the center of the island 1 and the distance between the plating ends and the reference value of the master image is greater than a certain threshold value. In other words, it is determined that plating area deviation has occurred (FIG. 8A).

  By the way, the plating is not always applied from the tip of the inner lead, but there are some which are applied in the middle of the inner lead. In that case, the distance between the inner plating end, the outer plating end, and the island center is obtained in each direction, and the plating area deviation is detected by comparison with the reference value (FIG. 8B). There is another method (FIG. 8C). I want to determine if the plating ends on the island side and dam bar side are within the intersection. Therefore, in the Y direction, the island side plating end reference MIy = (MSy + MSy ′) / 2 and the dam bar side plating end reference MOy = (MEy + MEy ′) / 2 are obtained. The plating end reference MIx and MOx are similarly calculated for the X direction. Then, in the island side and dam bar side plating end reference, the comparison between the reference value and the measured value, | MI-MS |, | MI-MS '|, | MO-ME |, | MO-ME' | If this value is within the set tolerance, it is determined that the product is non-defective and the tolerance is not acceptable. The tolerance (threshold value) may be common to eight locations or may be individual.

  For example, the plating state is managed as follows. Image information is obtained from a plating reference product (which may be the same as the workpiece from which the above inspection information was collected) by an imaging means corresponding to the plating method, and a histogram calculation area is set in the plated portion. The peak average luminance value is obtained from the above. Similarly, the peak average luminance value is obtained on the inspection work, and the difference from this reference value is calculated to manage whether this value is appropriate. Also, pass / fail judgment and trend management are performed by setting a non-defective product limit area to this value. A correlation (calibration curve) may be found between such an image evaluation value and a measured value that is numerically managed by, for example, a gloss meter in the plating step, and may be utilized for management of the plating state. Moreover, such plating management can also be used when the in-plane variation of the plate-shaped metal product is required, which leads to uniform plating state management throughout the plate-shaped metal product. Furthermore, necessary numerical information can be obtained and managed from other viewpoints such as hue, brightness, and saturation from RGB information on the image. FIG. 9 is an example in which the histogram peak average luminance is obtained from the standard workpiece (Base) and the inspection workpiece (Ins) of the same type, and there is a difference in the peak average luminance between the two types. This is an example.

  FIG. 10 shows an example of display of the inspection result. Necessary information can be obtained by outputting and displaying the inspection result and various trend information. Furthermore, by transmitting such numerical data to a higher-level backbone system via a network and feeding back quality information to the manufacturing process, it is also possible to use it for process improvement such as improvement of the yield rate.

  The plating inspection apparatus according to the present invention is an inspection apparatus that inspects plating quality using image information obtained by an imaging means corresponding to a plating method, and produces a comparison result obtained by comparing a tendency with a plating reference product. This makes it possible to provide an inspection apparatus with excellent defect detection sensitivity that can contribute to stabilizing the plating quality and can quickly find common defects such as plate-related defects. As a result, it is possible to cope with the miniaturization and mass production of the plate-like metal product accompanying the high density and high functionality of the semiconductor device.

  As an inspection device for inspecting plating quality, image information on the surface of a plate metal is obtained using an optimal imaging means according to the plating method, and inspection information obtained by performing appropriate image processing is used to improve the plating quality. It can contribute to maintenance and improvement.

DESCRIPTION OF SYMBOLS 1 ... Island or die pad 2 ... Inner lead 3 ... Outer lead 4 ... Dam bar 5 ... Frame part 6 ... Plating 7 ... Protective tape 8 ... Hanging lead 9 ...・ Space 10: Plate-shaped metal product (lead frame)
DESCRIPTION OF SYMBOLS 11 ... Die pad 12 ... Inner lead 13 ... Outer lead 14 ... Dam bar 15 ... Frame part 16 ... Plating 17 ... Protection tape 18 ... Lead 19 ... Space part 20 ... Conveying means 21 ... Conveying means operation start button 30 ... Imaging means 40 ... Illuminating means 41 ... Direct illumination 42 ... Indirect illumination 43 ... Inner wall 44 ... For imaging Opening 50 ... Camera 60 ... Processing control unit 70 ... Divided matching area 101 ... Lead frame

Claims (4)

An inspection apparatus for inspecting a plating quality defect of a plate-shaped metal product, the illumination means for irradiating the plate-shaped metal product with illumination light;
Imaging means for obtaining image information by imaging a plate-shaped metal product illuminated by the illumination means;
Conveying means for moving the plate-shaped metal product in one direction at a constant speed;
A supply / discharge section for supplying and discharging the plate-like metal products one by one on the conveying means;
Process the image information of the plating standard product of the plate metal product to obtain inspection information, and compare the inspection information with the image information of the plate metal product to determine the quality of the plating state of the plate metal product A process control unit that obtains the inspection result and controls the operation of the entire apparatus;
Storage means for storing image information and inspection results of the plate-shaped metal product, and image information and inspection information of a plating reference product,
With reference to the image information of the plating standard product, the plating state management means for comparing the inspection result of the metal plate product and the tendency of the image information,
A plating inspection apparatus characterized by comprising:   The plating inspection apparatus according to claim 1, wherein the plate-shaped metal product is a lead frame.   The plating inspection apparatus according to claim 1, wherein the imaging unit images the plate-shaped metal product that has reached the imaging position of the imaging unit in synchronization with the transport unit.   The plating inspection apparatus according to claim 1, wherein a comparison result obtained by a tendency comparison with a plating reference product is fed back to the manufacturing process.