JPH04367239A - Method of mounting electronic component - Google Patents

Abstract

PURPOSE:To mount an electronic component in an accurate position on a printed-circuit board or the like by a simple method. CONSTITUTION:The following are formed respectively on a printed-circuit board 2 by using a wire bonding apparatus: array reference pins 5 in a straight line shape along the arrangement direction of image sensor chips 3; and end-part reference pins 6 at end parts, on one side, of the arrangement of the image sensor chips 3. While the end part on one side of the image sensor chip 3 situated at the end part of the arrangement is brought into contact with the end- part reference pin 6 and the side part on one side of the long side of said image sensor chip 3 is brought into contact with the array reference pins 5, the image sensor chip 3 is mounted on the printed-circuit board 2. After that, the remaining sensor chips 3 are mounted while each end part on one side is brought into contact with each end part of the mounted image sensor chip 3 and each side part on one side of each long side is brought into contact with the array reference pins 5. Their positions on the printed-circuit board 2 are decided mechanically and their dislocation can be reduced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to electronic components, especially when a plurality of image sensor chips are arranged in a row, such as image sensors used in facsimile machines and image scanners. This article relates to a mounting method for electronic components for accurately arranging and mounting chips.

0002

[Prior Art] Conventionally, so-called one-dimensional array image sensors used in facsimiles, image sensors, etc.
It is common to have a structure in which a plurality of photoelectric conversion elements called an image sensor chip are arranged linearly on a printed circuit board (for example, Japanese Patent Laid-Open No. 63-40
(See Publication No. 443, etc.). As a mounting technique for multiple chips constituting such an image sensor, for example, a reference line indicating the mounting position of each chip is printed on the board in advance, and each chip is mounted along the printed reference line. It is well known to implement chips.

0003

[Problem to be solved by the invention] However, the image
The size of the photoelectric conversion element formed on the sensor chip is
Since the image sensor chip is approximately several tens of μm square, even if the image sensor chip is placed slightly off the reference line, the error in the sensor output will often be an unacceptable value, making it difficult to implement the chip. I had to be extremely careful. For this reason, there is a problem that not only is the work efficiency low, but also that the electrical accuracy of the image sensor depends on the skill level of the assembler. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for mounting electronic components with a simple operation and with extremely small placement errors.

0004

[Means for Solving the Problems] A method for mounting electronic components according to the present invention includes a plurality of column reference pins provided along the arrangement direction of a plurality of electronic components, and one end of the arrangement of the plurality of electronic components. Simply by mounting the electronic component while abutting it against one or more end reference pins provided in the row reference pin, or by bringing the electronic component into contact with the end of an adjacent electronic component and the row reference pin.
This method attempts to solve the above problem by mechanically determining the position of electronic components, thereby eliminating the need for operator skill.

[0005]

[Operation] Therefore, when an electronic component is mounted at one end of an array of electronic components, its corner comes into contact with the row reference pin and the end reference pin, and its mounting position is almost uniquely determined. If the end of the adjacent electronic component is brought into contact with the end of the component and one side of this adjacent electronic component is brought into contact with the row reference pin, the electronic component will be arranged at one end of the row. As with conventional electronic components, the mounting position can be almost unambiguously determined, and subsequent similar operations can be repeated to place and mount adjacent electronic components. It is possible to provide a mounting method for electronic components that is simple and has extremely small placement errors, in which the accuracy of the mounting position does not affect the precision of the mounting position and, by extension, the operation precision of the device using the electronic component. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electronic component mounting method according to the present invention will be described below with reference to FIGS. 1 to 3. Here, FIG. 1 is a plan view showing an example of the mounting state in the electronic component mounting method according to the present invention, and FIG. 2 is a plan view showing an example of the mounting state shown in FIG. FIG. 3 shows a perspective view of an image sensor chip, and FIG. 3 shows an explanatory diagram for explaining the procedure for installing column reference pins or end reference pins in the electronic component mounting method according to the present invention.

First, this embodiment shows a case where an image sensor is mounted as an electronic component used in a facsimile, an image scanner, etc.
A plurality of image sensor chips 3 are mounted on a printed circuit board 2.
This is a so-called one-dimensional array formed by arranging in a straight line. Each image sensor chip 3 has a plurality of photoelectric conversion elements 4 formed discretely on one side of a chip body made of an insulating material. Incidentally, since such an image sensor 1 is already well-known and well-known, a detailed explanation of its structure, characteristics, etc. will be omitted here. The image sensor chip 3 in this embodiment is formed into a rectangular parallelepiped, and the end portions of the image sensor chip 3 and the adjacent image sensor chip 3 are joined to each other in the longitudinal axis direction, and are arranged on the same straight line. (See FIG. 1), the actual dimensions of the planar shape shown in FIG. 1 are, for example, about 1 mm x 10 mm. Here, on one long side of each image sensor 1 (the upper side of the image sensor chip 3 in FIG. 1), two row reference pins 5, 5 are in contact with each image sensor chip 3. This prevents positional deviation from occurring when the image sensor chip 3 is mounted as described later.

[0008] Also, the image located at one end of the array
One end (the left end in FIG. 1) of the image sensor chip 3 (the image sensor chip 3 on the left side of the paper in FIG. 1)
The end reference pin 6 (details will be described later) is in contact with the
This prevents displacement of the mounting position of the image sensor chips 3 in the arrangement direction (left-right direction in FIG. 1). still,
In FIG. 1, reference numeral 7 denotes a connection line that connects the printed wiring 8 formed on the printed circuit board 2 and the image sensor chip 3, and is provided by a well-known wire bonding method.

Next, the procedure for arranging and mounting the above-mentioned image sensor chip 3 will be explained with reference to FIG. Note that FIG. 3 shows a case where an end reference pin 6 is provided. First, in this embodiment, the printed circuit board 2
At the positions where the column reference pins 5 or the end reference pins 6 are provided, a square bonding pattern 9 made of a material such as copper is formed in advance by a well-known printed wiring technique. As will be described later, these include the column reference pin 5 and the end reference pin 6.
This is because the bonding pattern 9 is bonded by metal bonding using ultrasonic vibration. The column reference pins 5 and the end reference pins 6 in this embodiment are formed on the printed circuit board 2 by using a well-known wire bonding device used in the manufacturing process of semiconductor devices, etc., as described below. It is provided. In this example, a wire bonding device that uses both thermocompression bonding and ultrasonic bonding is assumed, but since such a wire bonding device is already known and well-known, the details regarding the device itself will be explained below. Detailed explanation will be omitted. Furthermore, it goes without saying that the bonding pattern 9 is not limited to the square shape described above.

First, the printed circuit board 2 is placed on a bonding stage (not shown) of a wire bonding machine, and the position above the position where the row reference pins 5 or the end reference pins 6 are to be provided, that is, in this embodiment, is bonded. The capillary 10 is moved above the pattern 9 for use. A metal wire 12 that will become the connection wire 7 is inserted in advance into the wire insertion hole 11 of the capillary 10, and this metal wire 12 is used. Specifically, the metal wire 12 is preferably, for example, a gold wire, but is not particularly limited thereto. Further, the wire diameter of this metal wire 12 is, for example, 25
The thickness is approximately 28 μm to 28 μm. Then, a high voltage is applied between the metal wire 12 and the electric torch electrode rod 13 protruding near the tip of the capillary 10 via a circuit (not shown) to generate an arc discharge. Then, due to this arc discharge, the tip of the metal wire 12 is melted to form a spherical part 12a (see FIG. 3(a)). Then, after moving the electric torch electrode rod 13 from the tip of the capillary 10 in the lateral direction (in the left-right direction in FIG. 3), the capillary 10 is lowered and the spherical portion is placed on the bonding pattern 9. 12 are joined together and separated from the metal wire 12 to form gold particles 14. In this embodiment, the diameter of the spherical portion 12 is about 50 to 70 μm, and can be set to a desired size within this range. According to tests conducted by the applicant, the difference between the desired diameter and the actually obtained diameter is approximately ±2 μm.Furthermore, the deviation of the center, that is, the rate of deformation from the ideal circle, is as follows: ±5μ
It was about m.

Next, the starting switch of the ultrasonic device (not shown) is turned on. Since the ultrasonic vibration transmitting member 15 is attached to the capillary 10, when the start switch of the ultrasonic vibrating device is turned on, the ultrasonic vibration transmitting member 15 and the capillary 10 are attached to the previous granular material 14. For example, ultrasonic vibrations with an amplitude of 1 μm or less and a frequency of 50 to 60 KHz are transmitted. As a result, the granular material 14 and the connecting pattern
Frictional heat is generated between the particulate material 14 and the bonding pattern 9, and in addition to this frictional heat, heat from a heater (not shown) that warms the printed circuit board 2 is added, and the particulate material 14 and the bonding pattern 9 are bonded together. They are mutually fixed by metal bonding and thermocompression bonding, and the end reference pin 6 (or row reference pin 5) is completed. Note that even after the capillary 10 is pressed against the granular material 14, it gradually descends, so that thermocompression bonding is performed together with ultrasonic bonding. Therefore, the end reference pin 6 (or the row reference pin 5) is finally formed into a substantially flat shape as shown in FIG. 3(b). Hereinafter, the other row reference pins 5 are bonded to the bonding pattern at their respective predetermined positions using ultrasonic bonding and thermocompression bonding in the same manner as described above.
It is designed to be connected to the

Here, the position of the end reference pin 6 is determined based on the image.
It is preferable to locate it approximately at the center of the short side of the sensor chip 3. Also, regarding the position of the row reference pin 5, please refer to the image.
From the viewpoint of mechanical stability, it is preferable for the sensor chip 3 to be spaced apart from both ends of the long side by a length LB obtained by multiplying the length LA of the long side by a constant 0.211 (see FIG. 1). Incidentally, the constant 0.211 is a value obtained empirically from a mechanical mechanical viewpoint. After providing the end reference pins 6 and the column reference pins 5, the image sensor chip 3 will be arranged and mounted. First, the image sensor chip 3 located on the end reference pin 6 side (Fig. While touching the end of the image sensor chip 3 on the side of the end reference pin 6 (on the left side of the paper in FIG. 5, that is, the corner part extending from the end of the image sensor chip 3 in the longitudinal axis direction to the side part along the longitudinal axis (the upper side of the image sensor chip 3 in FIG. 1). 3a, if the image sensor chip 3 is placed on the printed circuit board 2 with the end reference pins 6 and the row reference pins 5 in contact with each other, the position of the image sensor chip 3 can be determined almost uniquely. It happens. Note that adhesive is applied in advance to the back surface of the image sensor chip 3 (the surface to be bonded to the printed circuit board 2), and by pressing the image sensor chip 3 against the printed circuit board 2, the printed circuit board 2 It is designed to be fixed to.

Next, one end of the adjacent image sensor 3 (on the right side of the paper in FIG. 1) is attached to the other end of the image sensor chip 3 placed at the end (on the right side of the paper in FIG. 1). The left end of the central image sensor chip 3 is brought into contact with the adjacent image sensor chip 3.
The image sensor chip 3 is bonded to the printed circuit board 2 while one long side (the upper side in FIG. 1) of the image sensor chip 3 is brought into contact with the row reference pin 5. Thereafter, by arranging and mounting the image sensor chip 3 in the same manner, unlike the conventional method, the mounting work of the image sensor chip can be carried out almost mechanically without paying close attention to the mounting position on the board. Complete.

Finally, the positional deviation when the image sensor chip 3 is arranged as described above will be compared with the conventional case. First, in the conventional method of arranging and mounting the image sensor chip 3 along a reference line for arranging the image sensor chip printed in advance on the board, for example, as shown in FIG. A case in which the position of the chip 3 is angularly shifted by α degrees with respect to the lateral direction of the placement reference line 16 (the horizontal direction in FIG. 4) will be specifically considered as follows. For example, α=0.
In the case of 2 degrees, the amount of deviation ΔY at the end on the right side of the paper in FIG.
If it is 0 mm, it is calculated as 10×SIN (0.2deg). That is, ΔY=0.0349mm=34
．． It becomes 9 μmm. Here, if the pixel density as an image sensor is 8 dots/mm, even the above deviation amount will not cause much of a problem as a reading error, but for example, if the pixel density is doubled, 16dot/
mm, the pixel spacing is 1/16mm = 62.5μ
m, the amount of deviation ΔY of the image sensor chip 3 is
If is the value mentioned above, the amount is approximately 60% (3
4.9/62.5=0.5584),
Simply thinking, this results in a reading error of approximately 60%.

On the other hand, when considering the amount of positional deviation that occurs when the image sensor chip 3 is mounted using the electronic component mounting method according to the present invention, first, the actual deviation that occurs with respect to the desired diameter of the spherical portion 12 is The diameter error is approximately ±2 μm, and the deviation of the center position of the spherical portion 12, that is, the amount of deformation from the ideal spherical shape is approximately ±5 μm. Assuming the worst case in which these two error factors occur independently, the maximum error amount in that case will be approximately ±7 μm. When the ratio of this maximum error amount to the pixel spacing (62.5 μm) when the pixel density is 16 dots/mm is calculated, it is approximately 10%, which is sufficiently small compared to the conventional method described above. If the ratio is moderate, it will have almost no effect on reading.

[0016]

Effects of the Invention According to the present invention, the column reference pins provided along the arrangement direction of a plurality of electronic components linearly arranged on a board and the end reference pins provided at the ends of the arrangement are provided with electronic components. By mounting the parts while making them contact each other, there is no need for the worker to visually determine the position where the electronic parts are to be mounted, unlike in the past, and the process is almost unaffected by the skill level of the worker. Since the mounting position of electronic components is mechanically determined to approximately the desired position, unlike the conventional method, the rate of deviation of the mounting position is drastically reduced, and even if deviation of the mounting position occurs, the skill level of the operator is reduced. Since the influencing factors are smaller than in the past, there is an effect that the influence on the operational accuracy of the apparatus is extremely small as in the past.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of mounting one image sensor chip in an embodiment of the electronic component mounting method according to the present invention.

2 is an overall perspective view of an image sensor chip disposed at one end of the image sensor 1 chip shown in FIG. 1; FIG.

FIG. 3 is an explanatory diagram for explaining the procedure for installing end reference pins and column reference pins in the electronic component mounting method according to the present invention.

FIG. 4 is an explanatory diagram for explaining errors in a conventional electronic component mounting method.

[Explanation of symbols]

Claims (1)

[Claims] 1. A method for mounting electronic components in which a plurality of electronic components are arranged and mounted in a row on a board, the method comprising: mounting the plurality of electronic components in the arrangement direction on the board on which the plurality of electronic components are mounted; A plurality of column reference pins are provided along the array, and one or more end reference pins are provided at one end of the array of the plurality of electronic components, and one end of the array of the plurality of electronic components is provided. The electronic component is mounted while the end reference pin and the plurality of array reference pins are brought into contact with the corner of the electronic component to be mounted in the section, and thereafter, a plurality of other electronic components are sequentially mounted. arranging the electronic components while bringing one end of the electronic component into contact with the end of an adjacent mounted electronic component and one side along the array with the column reference pin, respectively;
A method for mounting an electronic component, characterized in that the electronic component is mounted.