JP2000269553A - Method for mounting led array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent misalignment in a light emitting part, and also improve product quality by mounting an LED array with the center of gravity position of a light emission pattern as a reference. SOLUTION: A first LED array 1 is mounted on a substrate 7 by electrodes 4 for dots and common electrodes (a) and b, so as to be connected with common electrodes on the back face of a collet 3 and light emitting part electrodes at the both ends. Then, suitable currents are allowed to flow so that the light emission of the light emitting parts 2 at the both ends of the LED array 1 can be realized, and light emission patterns E are captured by a camera as image recognition patterns, and center of gravity positions G1 and G2 of the light emission patterns E of the light emitting parts are obtained. A straight line L1 connecting those points is obtained from each obtained center of gravity position and used as an ideal reference line. Similarly, the light emission patterns E of a second LED array 1 are captured as image recognition patterns, and center of gravity positions G3 and G4 of the light emitting parts 2 are obtained, and a straight line L2 connecting those points is obtained from the center of gravity positions. Then, the first LED array 1 and the second LED array 1 are arranged, so that the reference lines L1 and L2 are aligned, and the adjacent center of gravity positions G2 and G3 are arranged with equal distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED product having a structure exhibiting performance by mounting a plurality of LED chips having a plurality of light-emitting portions on the same substrate, and in particular to an LED product.
The present invention relates to a high-precision mounting method for an LED array used in an ED print head.

[0002]

2. Description of the Related Art An LED print head is conventionally known as a light source of an electrophotographic printer. An LED printer equipped with such an LED print head has a high reliability because an LED array as a light source is solid-state as a head and has no mechanical drive unit such as a laser printer. Since the length is short, miniaturization is possible. In a general laser system, a single light source scans the entire drum, so a complicated internal optical mechanism such as a polygon mirror is required. In the case of this LED array system, since the light sources are arranged in a line along the drum, there are no movable parts, and sharp printing can be performed up to the edge of the sheet while having a compact mechanism. In addition, since the LED array is manufactured using semiconductor manufacturing technology with a proven track record of mass production, cost reduction can be expected by mass production.

In the LED printer, the printing process proceeds in the following order. First, a uniform charge is applied to the photosensitive drum using a charger. Next, the light from the LED array is formed on the photosensitive drum surface via the converging rod lens array to form a latent image. Next, a visible image is formed by a developing machine, and then transferred and fixed on a recording paper. Further, the residual toner is cleaned and the residual potential is removed, and the printing process is completed. Incidentally, photosensitive drums having sensitivity characteristics suitable for the emission wavelength of the LED have been developed.

[0004] The material of the LED is required to be able to isolate light, perform a diffusion process capable of increasing the density, and obtain stable characteristics at an economical price. Currently, to meet these requirements,
GaAsP grown on a GaAs substrate by vapor phase is considered to be optimal.

In order to manufacture such an LED, an N-type G
An anti-diffusion film is formed on the aAsP epi-wafer by a CVD method or the like, and a light emission window is opened on the anti-diffusion film by a photolithography method. Next, the wafer and the P-type impurities are vacuum-sealed in a quartz ampoule and diffused at a temperature of about 700 to 800 ° C. for a maximum of several hours to form a PN junction in the light emitting window. Further, the diffusion temperature is set at a high temperature of 800 ° C. for several minutes to increase the surface concentration of the impurity sufficiently, and at a low temperature of about 600 to 700 ° C. for several hours to
There is also a method of spreading for tens of hours. 3 to 5 diffusion depths
μm is appropriate.

Then, an ohmic electrode is formed by depositing an Al alloy on the P side and an Au alloy on the N side, respectively. The size of the light emitting part is generally determined by the density (resolution), and the light emitting part per LED array is 64 depending on the LED array yield and size.
Elements or 128 elements are practical. The emission wavelength is determined by the composition of the material, and a peak wavelength of 660 nm is usually used in many cases.

FIG. 6 shows a main part of an LED printer head provided with an LED array in this LED printer. The light emitting portions 65 of the LED array 61 are die-bonded to a substrate in a straight line at equal intervals. IC 66 is die-bonded on both sides or one side with a conductive paste, and is electrically connected by wire bonding. Although not shown, signals and power are supplied to a board on which the LED array 61 is mounted via a flexible printed board. Whether or not the LED arrays 61 can be continuously connected is determined not only by the cutting accuracy of the LED array but also by the ability to perform the die bonding on the same substrate with high accuracy. Further, at present, the light amount variation of the light emitting unit 65 in the LED array 61 is 10% soil.
From one level to 40% of soil are contained in one wafer, and are selected by probing inspection, and those having a soil of 20% or less are used.

As described above, when the LED arrays 61 are die-bonded on a straight line and a plurality of light emitting portions 65 are arranged in one line, the pitch 63 between the light emitting portions 62 at the end of the adjacent LED array is required. It is required that the LED array 61 be die-bonded in a straight line so that the LED array 61 becomes equal to the pitch 64 of the light emitting units 65 in the LED array 61. For this reason, the finishing accuracy of the end face of the LED array 61 is stabilized, particularly, the end face accuracy of the back surface of the LED array 61 (the side opposite to the surface having the light emitting portion), particularly “burr”.
Is not preferred. The presence of this "burr" deteriorates the alignment accuracy and causes a problem that the dimension becomes wider than the distance between the light emitting parts.

As described above, the accuracy of the end face of the back surface of the LED array 61 affects the alignment accuracy (mounting accuracy). Therefore,
High precision cutting technology is required. A scribing method using cleavage is used for cutting the connection portion. With this method, it is possible to minimize the "burr" on the back surface when the wafer is divided. Thus, in recent years, L
Higher density (higher resolution) of the ED array is required, and cutting accuracy is also improving. As the density of the LED array increases, a method of mounting the LED array with high accuracy is required.

FIG. 7 shows a conventional mounting method of an LED array. As a method for mounting the LED array 71 on the substrate, the LED array 71 placed on the stage 76 is centered by the collet 72, and after being attracted, the collet driving unit 75 and the controller are moved to a predetermined position on the substrate 77.
It is moved by 73 and mounted. A conductive thermosetting resin is applied on the substrate 77, and the LED array 71 is mounted thereon. At this time, displacement due to movement occurs due to a mechanical error or the like, and it may not be possible to mount at the intended point. Therefore, a shift is detected by recognizing the image of the LED array 71 with the reference position by the camera 74, and the position is corrected by moving the LED array 71 on the substrate by the shift amount. As shown in FIG. 8, the reference position is the erroneous recognition electrode 84 on the adjacent LED array 81.
Often take. In addition, by recognizing the erroneous recognition electrode 84 with respect to the position recognition of the LED array 81 to be mounted, it is recognized as the deviation H from the reference position.

However, according to this mounting method, when the misrecognition electrode 84 and the light emitting portion 85 of the LED array 81 are misaligned, the LED array 81 moved on the substrate 87 is recognized by the electrorecognition electrode 84 as usual. When the position correction is performed, the light emitting unit 85 emits light at a position different from the intended position, and the function of the product may not be satisfied. The causes of the positional deviation between the electrode 84 and the light emitting portion 85 include a photolithographic mask for impurity diffusion for producing the light emitting portion and a photolithographic mask for producing the misrecognition electrode 84 on the wafer. It is necessary to adjust the above, but this may be caused by a shift at this time, a shift in the exposure amount, a stain on the mask, or the like. For this reason, it is difficult to correct the misalignment between the misrecognition electrode 84 of the LED array 81 and the light emitting unit 85 and mount the light emitting unit 85 at an accurate position based on the conventional electrode reference.

[0012]

As described above, as described above, LE
Since it is difficult to correct the misalignment between the misrecognition electrode of the D array itself and the light emitting unit and mount the light emitting unit at the correct position, the light emitting units of the high-resolution LED array are particularly linear and equidistant. Could not be implemented with.

According to the present invention, the shape of the light emitting pattern of the light emitting portion of the LED array is recognized, and L is determined based on the position of the center of gravity of the light emitting pattern.
An object of the present invention is to provide a method for mounting an LED array, which is intended to prevent displacement of a light emitting unit and improve product quality by mounting an ED array.

[0014]

According to the present invention, a plurality of LED arrays each including a plurality of light emitting units are mounted on a substrate,
In a mounting method in which the light emitting portions of the array are linear, a first LED array is mounted on the substrate, the light emitting portion of the first LED array emits light, and a light emitting pattern is detected. The LED array is made to emit light while being attracted by the collet to detect the light emission pattern, and the light emission portions of the second LED array are linearly and equidistantly based on the light emission pattern of the light emission portion of the first LED array. The mounting method of the LED array, which is characterized by repeating the mounting, recognizes and detects the center of gravity of the light-emitting pattern, thereby enabling high-precision mounting. The collet is L
The ED array is provided with electrodes for emitting light. Further, in the LED array, a common electrode is formed on a surface electrode having a light emitting unit, and the light emitting unit emits light by a current supplied from a collet.

[0015]

FIG. 1 shows a first embodiment of the present invention. FIG. 1 shows an order of a method of using an LED array 1 for an LED printer head and mounting the light emitting units 2 at both ends of each of a plurality of LED arrays 1 on the same substrate 7 so as to be linear and at equal intervals. FIG. Figure 2
As shown in FIG. 3, an LED array 1 having common electrodes a ′ and b ′ and 4 formed as dot electrodes is used, and processed into a shape such that the light emitting portions 2 at both ends of the LED array 1 can be seen as shown in FIG. It is implemented using the collet 3 that has been used.

The description will be given in the order of FIG. Order 1 of 1
In A, the LED array 1 is sucked by the suction nozzle 6 on the back of the collet 3. On the back surface of the collet 3, the common electrodes a 'and b' of the LED array 1 and the light emitting portion electrodes 4 'at both ends are provided.
A drive circuit (not shown) built in the dot electrode 4, the common electrodes a and b, and the collet 3 so as to contact and emit light (for example, the first and 128th when the LED array has 128 light emitting units). ) Forms a conductive pattern. After being attracted by the collet 3, the LED array 1 is centered, mounted on the substrate 7, and an appropriate current is applied, so that the light emitting units 2 at both ends of the LED array 1 emit light. At this time, the emitted light-emitting pattern E is captured as an image recognition pattern by a camera, and the first and 128th light-emitting portions 2 of the LED array 1 are obtained from the light-emitting pattern E.
Of the center of gravity G1 and G2 of the light emission pattern E of FIG. From the obtained positions of the centers of gravity, a straight line L1 connecting the points is obtained, and this is set as an ideal reference line. At this time,
The stylus 8 may be applied to the electrodes of the light emitting units 2 at both ends to apply an appropriate current to cause the light emitting units 2 at both ends to emit light.

Next, in step 2B of order 2, the light emitting portions 2 at both ends of the LED array 1 adsorbed to the collet 3 are divided into the light emitting portion electrodes 4 of the LED array 1 by the dot electrodes 4 on the back surface of the collet 3 and the common electrodes a and b. And the common electrodes a 'and b' are brought into contact with each other to emit an appropriate current to emit light. 2 which emitted light at this time
The points are captured by the camera, the light emission pattern E is taken as an image recognition pattern, and the center of gravity G3, G4 of the light emission section 2 is determined. A straight line L2 connecting the points is obtained from the obtained positions of the centers of gravity, and is used as an ideal reference line.

Next, in order 3, on the substrate on which the first LED array 1 is mounted, the second LED array 1 is placed on the reference line L1.
And L2 are mounted on a straight line. At this time, the reference line L2 is aligned with L1, and the adjacent centroid positions G2, G
In case 3 is 600 DPI, probe needle 8 is applied to light emitting portion electrode 4 ′ of first LED array 1, and second LED array is mounted in 3 A of order 3 so as to be arranged at a distance of 42 and 3 μm apart from each other. are doing. In order 3B, after the first LED array 1 is mounted, the image recognition pattern is stored and the second LED array 1 is mounted. As described above, the LED array 1 can be accurately arranged based on the image recognition pattern of the light emitting pattern E of the light emitting section 2 of the first LED array 1.

Next, a second embodiment of the present invention is shown in FIG. The LED array 1 'shown in FIG.
Although an LED array 1 'for an ED printer head is used, a common electrode a',
b 'is not provided. FIG. 4 is an explanatory diagram showing an order of a method of mounting such an LED array 1 ′ on the same substrate 7 so that the light-emitting portions 5 are linear and at equal intervals.

In the order 1B of FIG. 4, a collet 3 is used which is formed into a shape such that the light emitting portions 2 at both ends of the LED array 1 'can be seen as shown in FIG. The suction is performed by the suction nozzle 6. On the back surface of the collet 3, a dot electrode which contacts and emits light from the light emitting portion electrodes 4 ′ at both ends of the LED array 1 ′ (for example, the first and 128th when the LED array has 128 light emitting portions). 4 and a drive circuit (not shown). After being attracted by the collet 3, the LED array 1 'is centered, mounted on the substrate 7, and an appropriate current is supplied, so that the light emitting units 2 at both ends of the LED array 1' emit light.
At this time, the probe needles 8 may be applied to the light emitting unit electrodes 4 'at both ends of the LED array 1'. The emitted light-emitting pattern E is captured as an image recognition pattern by a camera, and from the light-emitting pattern, the center of gravity G1 of the light-emitting pattern E of the light-emitting portions 2 (first and 128th light-emitting portions) at both ends. Find G2. From the obtained positions of the centers of gravity, a straight line L1 connecting the points is obtained, and this is set as an ideal reference line.

Next, in 2B of order 2 in FIG. 4, the second LED array 1 '(second LED array 1') is attracted to the collet 3 and the second LED array 1 'is centered. The light emitting units 2 at both ends of the LED array 1 ′ are caused to emit light by applying probe needles 8 to the light emitting unit electrodes 4 ′ (first and 128th) and the back surface electrodes of the second LED array 1 ′. At this time, the two light emitting points are captured by the camera, and the light emitting pattern E is taken as an image recognition pattern to determine the center of gravity G3, G4 of the light emitting pattern. A straight line L2 connecting the points is obtained from the obtained positions of the centers of gravity, and is used as an ideal reference line.

Next, in order 3 in FIG. 4, the second LED array 1 'is mounted on the substrate on which the first LED array 1' is mounted such that the reference lines L1 and L2 are aligned. At this time, when the reference line L2 is aligned with L1 and the adjacent centers of gravity G2 and G3 are 600 DPI, the LED array position is determined based on the image recognition pattern on the substrate 7 so as to be arranged at a distance of 42 and 3 μm. By displacing them, they can be arranged accurately. In 3C of order 3 in FIG.
A probe needle 8 is applied to the light emitting portion electrode 4 'of the array 1' to mount the second LED array 1 '. In 3D of order 3 in FIG. 4, after mounting the first LED array 1 ', the image recognition pattern is stored and the second LED array 1' is mounted.

Here, the high-precision mounting method of the LED array 1, 1 'of 600 DPI has been described in detail, but other LED chips also have a plurality of array-like light-emitting parts other than the printer head. It is obvious to those skilled in the art that the present invention can be applied to a chip. Furthermore, L
The light emission pattern E of the light emitting units 2 at both ends of the ED arrays 1 and 1 '.
Although the reference line is obtained from the center of gravity of the light emitting unit, the reference line may be obtained from the center of gravity of the light emitting patterns of two or more light emitting units other than the light emitting units 2 at both ends. In this case, the collet needs to be processed so that the light emitting portion can be seen.

[0024]

When the light emitting portion of the LED array and the recognition electrode are shifted, the light emitting portion is shifted by the method of recognizing the electrode and recognizing the position of the LED array. However, according to the present invention, the light emitting pattern of the light emitting unit is recognized and aligned based on the center of gravity of the light emitting pattern of the light emitting unit. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a flow chart of a first embodiment of an LED array mounting method of the present invention.

FIG. 2 is a diagram showing an LED array used in the present invention.

FIG. 3 is a back view and a perspective view of a collet used in the first embodiment of the present invention.

FIG. 4 is a flowchart of a second embodiment of the LED array mounting method of the present invention.

FIG. 5 is a back view and a perspective view of a collet used in a second embodiment of the present invention.

FIG. 6 is a diagram showing a main part on which a conventional LED array is mounted.

FIG. 7 is a diagram showing a conventional LED array mounting method.

FIG. 8 is a diagram showing alignment of a conventional LED array mounting method.

[Explanation of symbols]

 1 ', 61, 71, 81 ... LED array 2, 62 ... Light emitting portions at both ends 3, 72 ... Collet 4, 4' ... Dot electrode 84 ... Misrecognition electrode 65 , 85 ... Light-emitting unit 6 ... Suction nozzle 66 ... IC 7, 67, 77, 87 ... Substrate 8 ... Probe needle H ... Displacement E ... Light-emitting pattern G1, G2, G3, G4: Position of the center of gravity of the light emission pattern L1, L2: Reference line a, a ', b, b': Common electrode 73: Controller 74 ...・ Camera 75 ・ ・ ・ Collet driver 76 ・ ・ ・ Stage

Claims (6)

[Claims] 1. A mounting method in which a plurality of LED arrays each including a plurality of light emitting units are mounted on a substrate, and wherein the light emitting units of each LED array are linearly mounted. Recognizing the light emission patterns of at least two or more light emitting units of the first LED array, and recognizing the light emission patterns of at least two or more light emitting units of the adjacent second LED array; An LED array wherein the light emitting patterns of the light emitting units of the second LED array are repeatedly mounted in a straight line at equal intervals based on the light emitting patterns of the light emitting units of the first LED array. How to implement. 2. The LED according to claim 1, wherein said light emitting patterns are light emitting portions at both ends of an LED array.
How to mount the array. 3. The LED array mounting method according to claim 1, wherein the recognition of the light emission pattern is performed by detecting a position of a center of gravity. 4. The light-emitting portions of the first and second LED arrays are arranged in a straight line, and the positions of the centers of gravity of the first and second LED arrays are arranged at equal intervals, with a line connecting the positions of the centers of gravity being used as a reference line. 5. The method for mounting an LED array according to claim 4, wherein: 5. The method according to claim 1, wherein the first and second LED arrays are attracted by a collet and mounted on the substrate, and at least a back surface of the collet is provided with dot electrodes for emitting the first and second LED arrays. 5. The L according to claim 1, further comprising a dot electrode and a common electrode.
How to mount an ED array. 6. The method according to claim 1, wherein the first and second LED arrays have a common electrode formed on a surface having a light emitting portion.