KR20130096381A - Inspection method for chip-embedded printed circuit board - Google Patents

Abstract

PURPOSE: A method for inspecting a printed circuit board of a built in chip type is provided to accurately measure by comparing raw data with a measured distance. CONSTITUTION: A substrate is comprised of a copper circuit (10) and a resin insulating layer. A cavity (20) is formed at the substrate. The chip is mounted at the cavity. The station coordinate of the x and y of a cavity shied (21) is detected. The station coordinate of the x and y of the chip is detected.

Description

Chip embedded printed circuit board inspection method {INSPECTION METHOD FOR CHIP-EMBEDDED PRINTED CIRCUIT BOARD}

The present invention relates to a method for inspecting a chip-embedded printed circuit board, and more particularly, to a method for inspecting whether a chip is properly seated at predetermined coordinates inside a cavity.

Recently, research and development of chip embedded printed circuit board technology, which directly fabricates a wafer-level chip into a printed circuit board, has been actively conducted. When the chip is embedded in the substrate, the size of the component is reduced, which helps to reduce the size and weight of the electronic device, and can remove parasitic components, thereby increasing the operating frequency of the circuit, as well as the noise of external electromagnetic waves. It has the advantage of blocking the impact.

As a component that may be embedded in a printed circuit board, there may be various electronic devices such as a semiconductor chip, a die, a module, a resistor, and a capacitor. In the following description, all of these components will be collectively referred to as a 'chip'.

The technique of processing the cavity and embedding the chip in the cavity is described in detail in Korean Patent Publication No. 10-2008-79391, Korean Patent Publication No. 10-2008-79384, and Korean Patent Publication No. 10-2008-79388. . Looking at the patent document of the embedded printed circuit board manufacturing patent disclosed in the Republic of Korea Patent Publication No. 10-2008-79388, to produce a cavity in the insulating layer by processing a copper cladded laminate (CCL), the adhesive tape at the bottom of the insulating layer After attaching, the electronic part is pushed into the cavity and seated on the adhesive tape. The semi-cured fluid resin such as PREPREG is laminated and heat-compressed to seal the cavity gap with the resin to seal the electronic part in the cavity. The present invention discloses a technique of physically peeling off and removing an adhesive tape after fixation therein.

After the chip is placed in the cavity, the hole is processed and plated with a laser drill or the like on the sealed resin to electrically connect the chip terminal and the circuit of the substrate to each other. By the way, if the chip is not seated exactly in the design position inside the cavity, misalignment may occur in the hole processing and plating process for the electrical connection. Therefore, it is necessary to check whether the chip is seated at the correct coordinate position inside the cavity for the subsequent process.

In general, a substrate panel is composed of a plurality of repeating strips, and the panel is prepared by manufacturing a reference point or mark for alignment, and for accurate positioning during laser processing, chemical etching, seating, or mechanical drilling process steps. Use it as a reference point.

1A and 1B illustrate a method of aligning at a specific point and a block unit reference point according to the related art. As shown in FIG. 1A, since the point method is influenced by the panel scale as it moves away from the reference point, a cumulative tolerance occurs.

In addition, the inspection in units of blocks shown in 1b is not easy due to the influence of the scale of each block. For automated inspection, the inspection should be done by inputting accurate coordinate data. However, since the coordinate setting by each block scale is different, it is difficult to cope with automation. In addition, the block-by-block inspection is possible, but the measurement time is long.

The prior art shown in FIGS. 1A and 1B has difficulty in obtaining accurate position data due to various variables such as panel scale, cavity pull, chip size, and the like. Furthermore, according to the related art, a data method of determining a position where a chip is seated by calculating a reference mark and coordinates on which each chip is placed through coordinate recognition is used for data sorting of coordinates of many chips seated in a panel cavity. There is a problem that takes a considerable time.

Accordingly, a first object of the present invention is to provide a method for accurately measuring and inspecting a position of a chip embedded in a cavity in a chip embedded printed circuit board.

A second object of the present invention is to provide a method for rapidly data processing a position of a chip embedded in a cavity of a chip embedded substrate in addition to the first object.

In order to achieve the above object of the present invention, the present invention is characterized by measuring the position of the chip with the cavity center as the origin, and in the front direction of the panel to determine the cavity position through image recognition by the front light. At the rear of the panel, the position of the chip is determined by determining whether the backlight is transmitted.

According to the present invention, the position of the chip is measured by measuring the origin of the cavity using the front light and the difference of contrast using the backlight, thereby securing accurate position data. The present invention has the advantage that it is easy to determine whether the chip is tilted by minimizing the measuring point and measuring the distance from the cavity center to the chip center. The present invention can measure quickly and accurately by comparing the raw data with the measured distance. In addition, since the present invention is applied regardless of the size of the cavity and the number of parts embedded in the cavity, the present invention can be applied to all chip-embedded printed circuit boards.

In addition, the present invention can not only easily classify and secure data by measuring the distance from the cavity origin to the chip and comparing it to the numerical value input in the design, but also rapidly predict the data even when the cavity size and chip size are changed. It can be secured. As a result, the quality and yield of the chip embedded printed circuit board can be improved.

1a and 1b show a prior art;
Figure 2a is a view showing the step of locating the cavity using the front light in accordance with the present invention.
Figure 2b is a view showing the image obtained when the front light on the front panel and the camera image capture.
Figure 2c is a view showing the step of locating the chip using the backlight in accordance with the present invention.
Figure 3a is a view showing a method for checking the position of the chip by measuring the distance from the left and right ends of the cavity according to the first embodiment of the present invention.
FIG. 3B is a diagram illustrating a method of inspecting a chip position by measuring a distance from a cavity origin according to a second embodiment of the present invention. FIG.
4 is a table showing the results of examining the position of the chip seated in each of the cavity of the panel, according to a preferred embodiment of the present invention.

The present invention examines whether the chip is seated in the correct position by measuring the position coordinates of the chip embedded in the individual cavity, with the center of the individual cavity fabricated in each strip as the origin of the distance measurement. The present invention calculates the reference point by calculating the center of the cavity by detecting the position of the cavity shield by irradiating the front light on the front side of the panel. Then, the back side of the panel (back side) is irradiated with light to determine the position of the chip in contrast to the contrast through the light transmission. At this time, the position of the chip is calculated based on the cavity origin.

A method of inspecting a chip mounting position in a cavity of a chip-embedded printed circuit board in which a cavity is formed on a substrate composed of a copper foil circuit and a resin insulating layer, the chip is seated in the cavity, and the semiconductor material is sealed and embedded. Detecting x and y position coordinates of the cavity shield formed along the cavity circumference by irradiating a front light on the front surface of the chip-embedded printed circuit board and capturing an image of the camera; (b) detecting x and y position coordinates of the chip seated in the cavity by irradiating a backlight on the back of the chip embedded PCB and measuring light transmittance; (c) Computing the center point x, y position coordinates of the cavity from the x, y position coordinates of the cavity shield measured in step (a), and from the x, y position coordinates of the chip measured in step (b) Calculating a center point x and y position coordinates to calculate a distance between the center point x and y position coordinates of the cavity and the center point x and y position coordinates of the chip as x and y coordinates; And (d) calculating a deviation between the raw data (the target value on the schematic) and the distance calculated in the step (c).

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

FIG. 2A is a view showing an image in which a camera recognizes a circuit and a cavity formed on a front surface of a panel by irradiating a front light on the front surface of the panel according to a preferred embodiment of the present invention.

Referring to FIG. 2A, a copper foil circuit 10 is shown on a substrate panel, and two chips 30a and 30b are seated in the cavity 20. Referring to the cavity portion of FIG. 2A, an image is shown in which a cavity shield (may be referred to as a 'cavity ring') defining a circumferential region of the cavity is formed. The present invention is characterized by individually identifying each cavity position produced in the panel by capturing an image of the cavity shield 21 by the measuring camera. That is, in contrast to the prior art of measuring the position coordinates of the embedded chip with a reference point based on an alignment key prepared in advance at an edge or a specific portion of the panel, the present invention relates to each of a plurality of cavities manufactured in the panel, The position of the cavity shield 21 is recognized by the camera as an image, and the reference point is set based on the center point of the cavity.

Once the reference point has been calculated, the location of the chip must be known. If the location of the chip is determined from the image obtained from the front light, some errors may occur. This will be described in detail again with reference to FIG. 2B.

Referring to FIG. 2B, the cavity shield 21 can be seen, and chips 30a and 30b are seated in the cavity 20. However, the camera photographing the front panel has a chip position due to a focusing error due to a step between the copper foil pattern and the chip, scattering of light due to the shape of the chip and the surface of the copper foil, and a cavity burr remaining during the etching process. It is not easy to figure out exactly. Looking at Figure 2b in detail, it is shown that there is an image of the cavity bur 22 remaining between the cavity shield 21 and the chips (30a, 30b).

In order to solve the problem of misidentification of the chip position coordinates caused by the error of the image captured by the camera, the present invention irradiates the backlight from the back of the panel instead of the front image recognition method, and contrast according to the degree of transparency vs. opaque. It is characterized in that the position of the chip to be detected by detecting.

FIG. 2C is an image of a back panel of a substrate panel irradiated with a backlight and measured by light transmission according to a preferred embodiment of the present invention. Referring to FIG. 2C, the pattern of the panel is not recognized, and only contrast vs. opaque is shown according to a difference in light transmittance with respect to the backlight light source of the measuring device. The panel portion and the chip portion having low light transmittance appear black, and the space between the cavity shield and the chip appears bright.

The present invention is characterized by determining the position coordinates of the chip by using the contrast contrast screen by the backlight. When applying the method shown in Figure 2c, it is possible to solve the reflection or scattering of light, errors caused by the cavity, and to measure the coordinates of the chip accurately.

3A is a diagram illustrating an inspection algorithm for determining whether a chip is seated in a design position, according to the first embodiment of the present invention. After the positional coordinates of the cavity are identified in the manner described with reference to FIG. 2A and the positional coordinates of the chip are identified in the manner described with reference to FIG. 2C, the distance a from the left side and the right side of the cavity shield 21 The chip 30a is checked for deflection by calculating the distance b, the distance o from the upper side, and the distance p from the lower side, and calculating the x-axis and y-axis deviations from the position coordinates (target value) on the design drawing.

In the same manner, the distance d from the left side of the cavity shield 21, the distance c from the right side, the distance q from the upper side, and the distance r from the lower side are calculated and compared with the position coordinates (target value) on the design drawing. By calculating the x-axis and y-axis deviation, it is checked whether the chip 30b is tilted.

3B is a diagram illustrating an inspection algorithm for determining whether a chip is seated at a design position, according to a second embodiment of the present invention. In the second embodiment of the present invention, after determining the position coordinate of the cavity in the manner described with reference to FIG. 2A, the center coordinate of the cavity is calculated, and after determining the position coordinate of the chip in the manner described with reference to FIG. 2C, the center coordinate of the chip. After calculating, the distance on the x-axis and y-axis from the center of the cavity to the center of the chip is calculated and compared with the target value on the design to determine whether the chip is tilted.

Compared to the first embodiment, the second embodiment of the present invention has an advantage that the amount of calculation is small so that the inspection device can display the result quickly. In addition, since the second embodiment of the present invention can be applied irrespective of the cavity size and the number of embedded chips, it may be applied to various chip embedded printed circuit boards.

FIG. 4 is a diagram illustrating a result of examining the position of a chip seated in each of the cavity of the panel according to a preferred embodiment of the present invention. A great advantage of the distance measurement method (second embodiment) using the cavity origin according to the present invention is that it is possible to immediately determine whether the chip is pulled through the numerical input of the raw data (target value in the design). The inspection method according to the present invention can be automated by programming and embedding software in the three-dimensional camera inspection equipment.

The foregoing has somewhat improved the features and technical advantages of the present invention in order to better understand the claims of the invention described below. Additional features and advantages that constitute the claims of the present invention will be described in detail below. It should be appreciated by those skilled in the art that the disclosed concepts and specific embodiments of the invention can be used immediately as a basis for designing or modifying other structures to accomplish the invention and similar purposes. In addition, the inventive concepts and embodiments disclosed herein may be used by those skilled in the art as a basis for modifying or designing other structures to accomplish the same purpose of the present invention. It will be apparent to those skilled in the art that various modifications, substitutions and alterations can be made hereto without departing from the spirit or scope of the invention as defined in the appended claims.

The present invention can be applied to chip embedded printed circuit boards and package substrates mounted in portable small devices such as smart phones and smart pads that require electronic components of a light and small form. Since the present invention is applied regardless of the size of the cavity and the number of parts embedded in the cavity, it is determined that the present invention can be applied to all chip-embedded printed circuit boards.

10: copper foil circuit
20: cavity
30a, 30b: chip
21: Cavity Shield
22: cavity bur

Claims (2)

In a method of inspecting a chip mounting position in a cavity of a chip embedded printed circuit board in which a cavity is formed on a substrate composed of a copper foil circuit and a resin insulating layer, and the chip is placed in the cavity and sealed with an insulating material, the chip is embedded.
(a) detecting x and y position coordinates of the cavity shield formed along the cavity circumference by irradiating a front light on the front surface of the chip embedded PCB and camera capturing an image;
(b) detecting x and y position coordinates of the chip seated in the cavity by irradiating a backlight on the back of the chip embedded PCB and measuring light transmittance;
(c) Computing the center point x, y position coordinates of the cavity from the x, y position coordinates of the cavity shield measured in the step (a), and from the x, y position coordinates of the chip measured in the step (b) Calculating a center point x and y position coordinates to calculate a distance between the center point x and y position coordinates of the cavity and the center point x and y position coordinates of the chip as x and y coordinates; And
(d) calculating a deviation between the raw data (target value in the design) and the distance calculated in step (c).
Chip embedded printed circuit board inspection method comprising a. Inspection equipment comprising a camera and software for performing the inspection method according to claim 1.

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