JP2007294876A - Light emitting element array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element array which reduces the occurrence of stray light and leakage light, prevents the cutting of bonding wire at a chip corner, and makes a covering process of a protect film unnecessary. <P>SOLUTION: Resin patterns 52, 64 are formed on a chip surface. An upper surface of a base layer is roughened. A stray light preventing wall 52 is arranged, and side surface thereof is roughened. The light emitted from the light emitter is shaded by the preventing wall, and is scattered by the preventing wall and the roughened surface of the base layer. Consequently, the occurrence of stray light and leakage light can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting element array, and more particularly to a light emitting element array chip with reduced stray light and leakage light.

  As shown in FIG. 1, in a light emitting element array used for an optical writing head of an optical printer, a facsimile machine, or a copying machine, a wire (gold wire) 14 is connected to a bonding pad 12 of each light emitting element 10 of the light emitting element array. Yes. In the figure, reference numeral 16 denotes a light emitting portion of the light emitting element. The light emitted from the light emitting unit is condensed on the photosensitive drum by, for example, a rod lens array.

  In such a light emitting element array in which wires are connected to each light emitting element, there is a limit to reducing the pitch of the light emitting portions because of the presence of bonding pads. The present applicant has proposed a self-scanning light-emitting element array using a light-emitting thyristor having a pnpn structure as the number of bonding pads is reduced and the arrangement pitch of the light-emitting element array is reduced (see Patent Document 1). Note that the self-scanning light-emitting element array may be abbreviated as SLED (Self-scanning Light-emitting Device).

FIG. 2 shows an equivalent circuit of the SLED chip. This SLED chip is of a type in which the shift section array 20 and the light emitting section array 26 are separated. This SLED chip includes transfer elements T ₁ , T ₂ , T ₃ ,..., And light emitting elements L ₁ , L ₂ , L ₃ . A three-terminal light-emitting thyristor is used for both the transfer element and the light-emitting element. The gate electrodes of the transfer elements are coupled by diodes D ₁ , D ₂ ,. V _GA is a power source (usually −5 V), and is connected from the V _GA line 23 to the gate electrode of each transfer element via the load resistance _RL . The gate electrode of the transfer element is also connected to the gate electrode of the corresponding light emitting element. The cathode electrode of the transfer element is connected to clock pulse terminals φ1 and φ2 via transfer clock pulse φ1 and φ2 wirings 21 and 22 alternately. The resistors R1 and R2 are current limiting resistors inserted in the wirings 21 and 22, respectively. A cathode electrode of the light emitting element passes through the light-emitting element feed line 24, is connected to the light emitting element feed terminal phi _I. Resistor R _I is a current limiting resistor that is charged to line 24.

According to this SLED chip, as shown in FIG. 3, it is only necessary to provide four bonding pads 12 at one end of one chip.
JP-A-2-263668

  However, the conventional light emitting element array has a problem that a printed image is easily affected by light from other than the light emitting portion, that is, stray light or leakage light.

  First, stray light will be described. Wire connection to bonding is usually performed by ball bonding in which a gold ball is bonded to an aluminum bonding pad and stitch bonding in which a gold wire is pressed and bonded to a terminal of a wire frame or a printed wiring board. First, ball bonding is performed, then stitch bonding is performed, and the gold wire is cut.

  When there is one wire for each light emitting element as in the light emitting element array shown in FIG. 1, as shown in FIG. 4, the light emitted from a certain light emitting part 16 is converted into a wire 14 or a gold ball near the light emitting part. 18 may be reflected as stray light. In particular, when there are variations in the shape of the wire loop, the generation of stray light becomes a serious problem.

  If there is no variation in the loop shape of the wire 14, even if stray light is generated, the wire exists uniformly, so that the influence of the stray light is not so noticeable in the printed image.

  However, in the case of the SLED chip of FIG. 3 where the wires are sparsely present, stray light is strong only in the place where the wires and balls are present, and therefore the influence of stray light is very conspicuous in the printed image. Thus, in the case of the structure of the SLED chip, the problem of stray light becomes more serious.

  As shown in FIG. 5, the SLED chips 20 are arranged in a staggered manner to constitute the light source of the optical writing head. As described above, in the head in which the SLED chips 20 are arranged in a staggered manner, the ends of the chips overlap in the main scanning direction (chip arrangement direction). For example, when the arrangement interval of the bonding pads 12 per chip is 100 μm and the chip length is 6 mm, a location where eight wires are concentrated in a range of about 1 mm appears every 12 mm. The effect of stray light is very noticeable. It has been found that stray light is mainly caused by reflection at a portion of the loop where the wire stands up to a height of 50 μm or more and reflection at the ball surface.

  Next, leakage light will be described. For example, in the SLED chip, since the light emitting thyristors are used for the shift portion array and the light emitting portion array, light is also emitted from the light emitting thyristors of the shift portion array.

  FIG. 6 shows a cross-sectional view of the thyristor of the light emitting section array and the thyristor of the cyst section array. The thyristor of the light emitting section array includes a p layer 30, an n layer 32, a p layer 34, an n layer 36, and a cathode electrode 38. The thyristor of the shift unit array includes a p layer 30, an n layer 32, a p layer 34, an n layer 36, and a cathode electrode 40.

  The cathode electrode 38 is connected to the wiring 24 and the cathode electrode 40 is connected to the wiring 21 or 22 through a contact hole provided in the insulating layer 42.

  In such a structure, leakage light due to leakage of the carrier recombination region 44 in the lateral direction, leakage light from the pn junction surface 46 where carrier recombination occurs, and light emission at the pn junction surface are multiple reflected on the semiconductor layer. As a result, leakage light is generated.

  In order to block such leakage light, it is conceivable to form a gold-based material on the semiconductor layer. However, since the gold-based material is very expensive, there is a problem in terms of cost.

  Further, in the conventional light emitting element array chip, the wire shown in FIG. 4 may come into contact with the corner of the chip, and the wire may be cut.

  Furthermore, the conventional light emitting element array chip has a protective film formed on the surface, but the process of coating the protective film increases the cost, and the heat treatment in the process of coating the protective film accelerates the deterioration of the contact hole. There's a problem.

  An object of the present invention is to provide a light emitting element array chip that solves these problems.

1. Solution to stray light due to reflection on gold wire and gold ball (1) A resin pattern is provided between the light emitting part on the chip surface and the wire bonding pad to reduce the amount of light that comes out of the light emitting part and reaches the wire or ball. . Thereby, the stray light by reflection with a wire or a ball can be reduced.

(2) In particular, when arranged in a staggered manner like an SLED chip, a resin pattern having a rough side surface is provided between the light emitting part and the wire bonding pad of the adjacent chip, thereby coming out of the light emitting part. Not only is the light reflected by the resin pattern, but the light transmitted through it is scattered when passing through the rough surface, so stray light is further reduced.
The rough surface of the resin pattern side is created as follows. That is, when the wafer is cut into chips, the blade (blade) of the cutting machine passes through a dicing line between the chips. By providing resin on this line, the cut surface of the resin is a blade. The surface unevenness becomes a rough surface due to contact with the light, and when the light from the light emitting portion passes through the resin in the direction of the wire and is emitted, it is scattered by the rough surface, so that the amount of light reaching the wire and the ball is reduced.

(3) When a resin is provided by a stamper between the light emitting part and the wire bonding pad, a light shielding resin wall (hereinafter referred to as a stray light preventing wall) higher than the light emitting part is created by the recess of the stamper. . The stray light prevention wall is provided between the bonding pad and the light emitting portion of the adjacent chip in contact with the chip having the pad.

  The side surface outside the chip of the stray light prevention wall is a cut surface formed by being cut by a cutting machine. The cut surface of the resin has sufficient roughness to scatter and diffusely reflect the light from the light emitting part of the adjacent chip, reducing the amount of light that is reflected by the wire and ball and becomes stray light it can.

2. Solution to Leakage Light and Stray Light due to Reflection Leakage light can be reduced by covering the entire resin chip with the resin pattern at least excluding the bonding pad portion. If the surface of the stamper used to mold the resin pattern (the surface on which the lens and base are created) has fine irregularities, it will come out from below at least on the surface of the resin pattern that covers the entire chip area except the bonding pad. The amount of light that reaches the rod lens array can be reduced by scattering the leaked light. Further, since the base surface is a rough surface, the amount of light in the direction of the wire is further reduced.

3. Solution for preventing cutting of wire By cutting the chip end with resin, cutting of the wire is prevented.

4). Solution that eliminates the need for a protective film forming step By forming a resin film by molding on the entire surface excluding the bonding pad, the protective film forming step becomes unnecessary.

  As one aspect of the present invention, in a staggered light emitting element array chip, a resin pattern is part of a resin pattern that blocks light incident on a wire on a bonding pad of the other chip from a light emitting portion of one chip ( That is, the area occupied by both the stray light preventing wall and the resin surface on the surface of the chip is larger than the area occupied by the micro lens. Constitute. As a result, the ratio of the resin on the surface of the chip can be increased as compared to the conventional case, the excess resin can be easily washed, and the light amount of the light emitting element array due to the excess resin adhering to the microlens. Variations can be reduced.

  Furthermore, a part of the resin pattern (that is, the stray light prevention wall) is formed in the same shape as the lenticular shape or the microlens. In particular, if the stray light prevention wall is formed in the same shape as the microlens, the creation of the resin pattern in the chip manufacturing process can be simplified.

  Embodiments of the invention will be described below with reference to the drawings.

  In this embodiment, in order to increase the utilization efficiency of the light emitted from the light emitting part, a resin pattern for preventing stray light and preventing leaked light is formed at the same time in an SLED chip of a type in which a microlens is formed on the light emitting part. Is.

  The microlens is created by molding a resin on a light emitting portion using a stamper on a wafer on which an SLED is formed. The stamper is formed by etching the quartz glass substrate. In addition to the recess for forming the microlens, a recess for the stray light prevention wall having a depth of 19 μm is formed on the quartz glass substrate. Further, the surface of the stamper for forming the base portion other than the concave portions for forming the lens and forming the stray light preventing wall was roughened by polishing. The surface roughness Ra is preferably 0.05 μm or more.

  FIG. 7 shows a resin pattern formed on adjacent chips A and B arranged in a staggered manner using such a stamper. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along line LL in FIG. 7A.

  The minimum value of the horizontal distance between the center of the microlens 50 on the light emitting part of the chip A and the center of the ball 18 of the chip B is 94 μm. There is a wiring pattern from the pad 12 between the bonding pad 12 of the chip B and the boundary between the chip A, and the stray light prevention wall 52 is formed here. The maximum value of the height of the loop portion of the wire 14 from the surface of the element substrate is 90 μm. The side surface 54 on the chip A side of the stray light prevention wall 52 is a rough surface formed by cutting in the wafer cutting process, and the horizontal distance from the top of this surface to the center of the light emitting portion of the chip A is 16 μm. The height of the stray light prevention wall 52 from the element substrate surface is 25 μm, that is, the height from the base surface having a thickness of 6 μm is 19 μm.

  Actually, in order for the stray light prevention wall 52 to shield the light reaching the top of the wire 14 from the top of the microlens 50 on the light emitting portion, the height from the surface of the element substrate may be 23 μm. It is high enough as a stray light prevention wall.

  Further, the resin surface of the portion 56 other than the microlens 50 is a rough surface because it transfers the rough stamper surface shape. The roughness Ra of the rough surface is preferably 0.05 μm or more. The rough surface can scatter leaked light.

  If the resin is covered up to the corner of the chip, the wire 14 can be prevented from being cut by contact with the chip corner.

  In Example 1, the cut surface of the chip is inclined 5 ° with respect to the normal line of the horizontal plane to be die-bonded. This is to make the chip surfaces as close as possible when the chips A and B are die-bonded, but the inclination of the stray light prevention wall 52 is also inclined by 5 ° with respect to the normal line of the horizontal plane.

  In this embodiment, as shown in FIG. 8, the inclination θ of the rough surface 54 outside the chip of the stray light prevention wall is increased by further setting the inclination to 10 °. Accordingly, it is possible to reduce the probability that the scattered light 60 scattered by the rough side surface 54 of the stray light prevention wall 52 from the light emitting unit through the microlens 50 reaches the upper rod lens array. However, the angle 8 can be set to any angle other than 5 ° and 10 °.

  For the resin on the light emitting part of chip A, as shown in FIG. 9, the surface 62 of the base layer 64 is made rougher by making the surface of the stamper rougher, and the base layer 64 is made of a dicing line than before. The blade of the cutting machine cuts the base layer by forming the base layer. Thereby, the base layer side surface 66 became the same surface as the chip cut surface, and became a rough surface. At this time, the amount of light reaching the wire 14 and the ball 12 can be reduced and stray light can be suppressed by reducing the light rays coming out from the base layer surface 62 and the light rays coming out from the base layer side surface 66.

  In this embodiment, as shown in FIG. 10, an SLED chip without a microlens is provided with a stray light prevention wall 52, and a base layer 64 is covered in all regions except the bonding pad 12 and the light emitting portion 16. . As in FIG. 7, the side surfaces of the stray light prevention wall 52 and the surface of the base layer 64 are rough surfaces.

  In the light emitting element array, a resin pattern 68 is provided between the light emitting portion 16 and the wire bonding pad 12. FIG. 11A shows the case of an SLED chip, and FIG. 11B shows the case of a light emitting element array chip of the type shown in FIG.

  In particular, in the case of SLED chips arranged in a staggered manner, a resin pattern having a rough surface formed by dicing as a side surface may be used.

  In connection with Examples 1-5 mentioned above, when forming the stray light prevention wall 52 with resin, forming the resin surface 56 of the peripheral part of the micro lens 50 and the micro lens 50 produces a further effect. FIG. 12A shows a schematic view of a wafer in which an SLED chip is formed and a resin pattern is formed on the top. FIG. 12B is an enlarged view of an example showing an overview of the SLED chip in part (view A) of FIG. FIG. 12C is an enlarged view of another example showing an overview of the SLED chip in part (view A) of FIG. In the description of this embodiment, in FIGS. 12B and 12C, the microlens 50 is typically shown as a circular lens (ie, a spherical lens), but an aspherical lens (ie, a compound lens or An elliptic lens may be used.

  In FIG. 12B, the stray light prevention wall 52, the microlens 50, and the resin surface 56 around the microlens 50 are formed of the same photocurable resin, and resin is formed around the bonding pad 12 and the periphery thereof. I have not let it. In FIG. 12C, the stray light prevention wall 52, the microlens 50, and the resin surface 56 around the microlens 50 are formed of the same photocurable resin, and resin is formed around the bonding pad 12 and the periphery thereof. I have not let it. In the SLED chip shown in FIGS. 12B and 12C, the area of the resin surface 56 in the peripheral portion of the microlens 50 is different.

  Here, a technique for forming a resin pattern on the surface of the SLED chip will be described. For example, first, a photo-curing resin (an epoxy-based or acrylic-based photo-curing resin) is formed on the entire surface of the wafer. Next, a light-shielding film (for example, a Cr film) having a pattern for distinguishing between a region where the resin is to be removed and a region where the resin is to be removed is provided on the entire surface of the wafer, and the resin is cured only in the region where the resin is left. Next, a desired resin pattern can be formed on the surface of the SLED by washing the region that has not been UV-cured (that is, the region from which the resin is removed) with a dedicated solvent. Hereinafter, a resin that has not been cured by ultraviolet light is referred to as an uncured resin.

  On the other hand, when forming a desired resin pattern on the surface of the SLED, it is important to reliably remove the residue of the uncured resin. For example, if the uncured resin remains on the bonding pad, it may cause a conduction failure, and if the uncured resin adheres to the microlens 50, it may cause a variation in the light amount or a decrease in the light amount increase rate.

  However, in order to reliably remove the uncured resin residue to be cleaned, careful cleaning adjustment is required. Generally, the uncured resin is removed by finely controlling the cleaning time (for example, controlled in minutes). Therefore, in order to reduce the influence of the uncured resin, it is preferable to reduce the area of the uncured resin to be cleaned on the SLED. That is, in the SLED chips shown in FIGS. 12B and 12C, the SLED chip shown in FIG. 12B has less area to be cleaned than the SLED chip shown in FIG. Become. Furthermore, the SLED chip shown in FIG. 12C requires less area to be cleaned than the SLED chip (not shown) in which only the microlens 50 is formed. A small area to be cleaned means that the amount of resin to be cleaned is small, and the effect of facilitating cleaning is produced.

  Moreover, when the SLED chip shown in FIGS. 12B and 12C was actually formed with a cleaning time of 3 minutes, the SLED chip shown in FIG. 12B is shown in FIG. Compared to the SLED chip, it was confirmed that the light quantity variation (PRNU) was improved by 30%. In other words, it was confirmed that when the cleaning time was made relatively short, the residue of the uncured resin adhered to the microlens 50, causing variations in the amount of light. Therefore, the fact that the area to be cleaned is small has the effect of shortening the time to be cleaned and reducing the manufacturing cost.

  In the staggered SLED chip, the resin pattern is transferred from the light emitting portion 16 of one SLED chip to the wire on the bonding pad 12 of the other SLED chip so that the area to be cleaned is at least 1/2 of the conventional area. The area occupied by both the stray light prevention wall 52 and the resin surface 56 on the surface of each SLED chip is composed of the stray light prevention wall 52 that blocks incident light, the microlens 50, and the resin surface 56 around the microlens 50. It is preferable to make it larger than the area occupied by the microlens 50.

  Several specific examples in which the stray light prevention wall 52 is formed of resin will be described in relation to the above-described sixth embodiment. FIG. 13 is a plan view when the stray light prevention wall 52 on the surface of the SLED chip is formed at substantially the same height as the resin surface 56. Similar components will be described with the same reference numerals.

  On the other hand, FIG. 14 shows an example in which a lenticular dummy lens as the stray light prevention wall 52 is provided on the micro lens 50 side by side. FIG. 15 shows an example in which a lenticular dummy lens as the stray light prevention wall 52 is formed by shifting from the arrangement of the microlenses 50 on the cross section of the SLED chip (in the direction away from the bonding pad region 12) and cutting the chip later. Show. In this way, the height and position of the stray light prevention wall 52 are suitably adjusted by shifting the central axis in the main scanning direction, which is the apex of the lenticular dummy lens, from the arrangement of the microlenses 50 to the SLED chip cutting axis. Such suitable heights and positions will be apparent from the description below. In relation to FIG. 15, it is preferable that the central axis in the main scanning direction, which is the apex of the lenticular dummy lens (stray light prevention wall 52), coincide with the SLED chip cutting axis.

  Actually, the SLED chip shown in FIG. 15 was formed with the height of the lenticular dummy lens (stray light prevention wall 52) being 25 μm and the surface roughness Ra being 0.5 μm or more. When this SLED chip was used to form a staggered light emitting element array by stitch bonding, it was confirmed that stray light was not detected.

  FIG. 16 shows an example in which dummy lenses having the same shape as the microlenses are provided on the arrangement of the microlenses 50 as stray light prevention walls 52. FIG. 17 shows an example in which the stray light prevention wall 52 having the same shape as that of the microlens is formed by shifting the microlens 50 from the arrangement of the microlenses 50 on the cross section of the SLED chip (in the direction away from the bonding pad region 12). Is shown. As described above, by forming the microlens shape instead of the lenticular shape, the creation of the resin pattern in the manufacturing process can be simplified.

  FIG. 18 shows an example in which a dummy lens having the same shape as the microlens is provided as a stray light prevention wall 52 on the arrangement of the microlenses 50, and the resin surface 56 around the microlenses 50 is overlapped. .

  It is obvious that various modifications can be made from the examples shown in FIGS. In FIGS. 13 to 18, the micro lens 50 is typically shown as a circular lens (that is, a spherical lens), but may be an aspheric lens (that is, a compound lens or an elliptic lens).

  Next, how to adjust the height and position of the stray light prevention wall 52 appropriately will be described. FIG. 19A is a cross-sectional view showing an example of a staggered light emitting element array using the stitch bonding 78. FIG. 19B is a cross-sectional view showing an example of a staggered light emitting element array using the ball bonding 18. First, in the case of a staggered light emitting element array, the main cause of stray light is often due to reflection of bonding wires. Therefore, it is preferable to provide the stray light prevention wall 52 so that the light emitted from the light emitting unit 16 does not directly irradiate the bonding wire.

  Each of the SLED chips shown in FIGS. 19A and 19B is an SLED chip facing 42.3 μm, which is twice as large as the light emitting portion pitch in the main scanning direction of 1200 dpi (about 21.16 μm), for example. This is an example in which the distance of the light emitting unit is used (see FIG. 5). Note that the distance between the light emitting portions of the SLED chips facing each other is a value required by design in an image writing device using a light emitting element array, and is generally an integer multiple of the light emitting portion pitch in the main scanning direction. . At this time, as shown in FIGS. 19A and 19B, the distance from the end surface of the SLED chip to the center of the light emitting portion is 27 μm. The bonding height is exemplified as 50 μm in FIG. 19A and 100 μm in FIG. 19B, but is defined as a required height in terms of the structure of the light emitting element array. In the case of stitch bonding (FIG. 19A), the height of the stray light prevention wall 52 is preferably 15 μm or more. In the case of ball bonding (FIG. 19B), the height of the stray light prevention wall 52 is 30 μm or more. Is preferred.

  Therefore, as shown in FIG. 20, the angle (elevation angle θs) when looking up the bonding wire from the light emitting portion is necessary as the stray light prevention wall 52 when a predetermined value is required as the distance between the light emitting portions of the SLED chips facing each other. The height is determined. Thus, the mold for providing the resin pattern on the SLED chip can be configured very easily.

  In each of the above embodiments, the light emitting element array chip has been described. In this embodiment, an optical writing head using such a light emitting element array chip will be described.

  FIG. 21 shows an example of an optical writing head using the light emitting element array of the present invention. A plurality of light emitting element array chips 71 in which light emitting elements are arranged in a row are mounted on the chip mounting substrate 70 of the optical writing head 100 in the main scanning direction, and light emitted from the light emitting elements of the light emitting element array chip 20 is emitted. An erecting equal-magnification rod lens array 72 long in the main scanning direction is fixed by a resin housing 73 on the optical path. A photosensitive drum 74 is provided on the rod lens array 72. Further, a heat sink 75 for releasing heat of the light emitting element array chip 20 is provided on the base of the chip mounting substrate 70, and the housing 73 and the heat sink 75 are fixed by a fastener 76 with the chip mounting substrate 70 interposed therebetween. ing.

  Next, an optical printer using such an optical writing head will be described. The basic structure of the optical printer is shown in FIG. An optical writing head 100 is installed in the optical printer. A photoconductive material (photosensitive member) such as amorphous Si is formed on the surface of the cylindrical photosensitive drum 102. The drum rotates at the printing speed. The surface of the photosensitive drum of the rotating drum is uniformly charged by the charger 104. Then, the optical writing head 100 irradiates the photosensitive member with the light of the dot image to be printed, neutralizes the charge where the light hits, and forms a latent image. Subsequently, the developing device 106 applies toner to the photoconductor according to the charged state on the photoconductor. The transfer device 108 transfers the toner onto the paper 112 sent from the cassette 110. The sheet is heated and fixed by the fixing device 114 and sent to the stacker 116. On the other hand, the drum that has been transferred is neutralized by the erasing lamp 118 over the entire surface, and the remaining toner is removed by the cleaner 120.

  Such an optical writing head can be used not only for printers but also for facsimile machines and copying machines. FIG. 23 shows the basic structure of a facsimile or copying machine. The same components as those in FIG. 22 are denoted by the same reference numerals.

  Light is emitted from the light source 124 to the read original 122 conveyed by the paper feed roller 130, and the reflected light is received by the image sensor 128 through the imaging lens 126. Based on the output of the image sensor 128, the light emitting element array (including the light emitting element array chip 20) of the optical writing head 100 is turned on and irradiated to the photosensitive drum 102 via the rod lens array 72. Printing on the paper 112 is as described for the optical printer.

It is a figure which shows the wire bonding of the conventional light emitting element array chip. It is an equivalent circuit diagram of a self-scanning light emitting element array. It is a figure which shows the wire bonding of a self-scanning light emitting element array chip. It is a figure which shows generation | occurrence | production of a stray light. It is a figure which shows the staggered arrangement of an SLED chip. It is a figure which shows generation | occurrence | production of leak light. It is a figure which shows one Example of the light emitting element array chip | tip of this invention. It is a figure which shows one Example of the light emitting element array chip | tip of this invention. It is a figure which shows one Example of the light emitting element array chip | tip of this invention. It is a figure which shows one Example of the light emitting element array chip | tip of this invention. It is a figure which shows one Example of the light emitting element array chip | tip of this invention. It is the schematic of the wafer in which the light emitting element array chip | tip of one Example by this invention was formed. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. 1 is a view showing a light emitting device array chip according to an embodiment of the present invention. It is a figure showing the relationship between the angle which looked up at the bonding wire from the light emission part, and the height of a stray light prevention wall. It is a figure which shows the structure of an optical writing head. It is a figure which shows the basic structure of an optical printer. It is a figure which shows the basic structure of a facsimile or a copying machine.

Explanation of symbols

12 Bonding pad 14 Gold wire 16 Light emitting portion 18 Gold ball 50 Micro lens 52 Stray light prevention wall 54 Side surface 64 of stray light prevention wall Side surface 100 of base layer Optical writing head

Claims (15)

  A light emitting element array chip, wherein at least a part of a surface of a chip including a bonding pad is covered with a resin pattern.   The light emitting element array chip according to claim 1, wherein the resin pattern covers a chip surface other than the bonding pads.   The light emitting element array chip according to claim 1, wherein at least one side surface of the resin pattern is a rough surface.   The light emitting element array chip according to claim 1, wherein an upper surface of the resin pattern is a rough surface.   The light emitting element array chip according to any one of claims 1 to 4, wherein a part of the resin pattern on the light emitting portion of the chip forms a microlens.   A part of the resin pattern is provided between a light emitting portion of a chip and the bonding pad, and is a height that shields light from the light emitting portion from entering a ball and a wire formed on the bonding pad. The light emitting element array chip according to claim 1, comprising:   The light emitting element array chip according to claim 1, which is a self-scanning light emitting element array chip.   When the self-scanning light emitting element array chips are arranged in a staggered manner and the bonding pad of the other chip faces the light emitting part of one adjacent chip, the other chip has a space between the light emitting part and the bonding pad. 8. The light emitting element array chip according to claim 7, wherein a part of the resin pattern has a height that blocks light from the light emitting part from being incident on a ball and a wire formed on the bonding pad. 9. .   The light emitting element array chip according to claim 8, wherein a side surface of a part of the resin pattern provided between the light emitting unit and the bonding pad is a rough surface and scatters light from the light emitting unit.   The resin pattern of the other chip is composed of a part of the resin pattern that shields light incident on the wire on the bonding pad from the light emitting part, the resin surface located in the peripheral part of the microlens and the microlens. 9. The light emitting device array chip according to claim 8, wherein an area occupied by both a part of the resin pattern and the resin surface on the surface of each chip is larger than an area occupied by the microlens.   The light emitting device array chip according to claim 10, wherein a part of the resin pattern is formed in a lenticular shape or the same shape as the microlens.   An optical writing head comprising the light emitting element array chip according to claim 1.   An optical printer comprising the optical writing head according to claim 12.   A facsimile comprising the optical writing head according to claim 12.   A copying machine comprising the optical writing head according to claim 12.

Images