JPH04349233A - Optical element and its packaging method - Google Patents

Abstract

PURPOSE:To perform the packaging with high positional accuracy by providing a matching mark on a substrate forming a photoelectric converting element. CONSTITUTION:In four photodiodes 105A, 105B, 105C and 105D, photodiodes 105A and 105B are formed on a substrate 106A and photodiodes 105C and 105D are formed on a substrate 106B respectively. When substrates 106A and 106B are packaged, a semiconductor laser 102 is driven and light-emitted. While the monitoring screen is watched, a light emitting point 101 is made coincident with the intersection of a reference line 108 and a reference line 109 on a screen. The packaging surface of a laser 102 and the reference line 108 are made parallel. The substrate 106A is rotated or moved and die-bonded from a Z axis direction to a pedestal 104 so that the matching mark 107A of the substrate 106A and reference lines 110 and 108 on the screen can be made coincident with each other. Further, the substrate 106B is also die-bonded. Thus, only by aligning the matching mark of the substrate to the reference line drawn on the monitoring screen, packaging is executed with the high positional accuracy.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element constituting an optical head and a method for mounting the same in the field of optical storage in which information is recorded and reproduced using light.

0002

2. Description of the Related Art Conventionally, a diffraction means consisting of two unequal periodic diffraction grating regions for dividing light from an optical storage medium in the directions of four photoelectric conversion elements, and an astigmatism consisting of the diffraction means and a condenser lens have been conventionally used. an aberration generating means, and a band-shaped four whose long axis direction is arranged radially around the optical axis of the 0th-order diffracted light of the diffraction means.
In an optical element having two photoelectric conversion elements and a light source, there are no limitations on the mounting method of the photoelectric conversion element other than mounting based on the light emitting point of the light source.

0003

[Problems to be Solved by the Invention] However, in the case of an optical head as described above in which a light source and a photoelectric conversion element are mounted in one package, the photoelectric conversion element must be mounted with extremely high positional accuracy relative to the light source. It becomes impossible to obtain focusing error and tracking error signals.

Conventionally, only the light emitting point was used as a reference, but since the photoelectric conversion element is in the form of a band with its long axis arranged radially around the optical axis, it is difficult to confirm the correct position from the light emitting point before mounting. is difficult.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide an optical element and a method for mounting the same, which enable mounting of a photoelectric conversion element with extremely high positional accuracy.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, an optical device and a method for mounting the same according to the present invention provide two optical devices that divide light from an optical storage medium in the directions of four photoelectric conversion devices.
a diffraction means consisting of two unequal periodic diffraction grating regions; an astigmatism generating means consisting of the diffraction means and a condensing lens; and a long axis direction arranged radially around the optical axis of the zero-order diffracted light of the diffraction means. In the optical element having the four band-shaped photoelectric conversion elements and a light source, two of the four photoelectric conversion elements are respectively arranged at the same position in the optical axis direction. A feature is that alignment marks are provided on the substrate.

[0007] The alignment mark is characterized in that it consists of a straight line parallel to the mounting surface of the light source and a straight line perpendicular to the parallel straight line.

When mounting the photoelectric conversion element, after aligning the reference line or mark in the field of view of the magnifying observation means of the mounting device with the light emitting point of the light source and the alignment mark,
It is characterized by implementation.

[0009]

Embodiment FIG. 1 is a front view (a) and a top view (b) of an optical device showing an embodiment of the present invention. The pedestal 104 is a part of the package, and the bottom surface of the package is parallel to the paper surface of FIG. 1(a), and the pedestal 104 protrudes from the bottom surface. This pedestal 10
A method for mounting a light source and a photoelectric conversion element on 4 will be described below.

First, the submount 103 is die-bonded to the pedestal 104 from the y-axis direction. Die bonding is performed by applying heat to the fusion metal deposited on the surface of the submount 103 and pressing it while melting it.

Next, a semiconductor laser 102 serving as a light source is die-bonded to a submount 103 from the y-axis direction. Die bonding is performed by pressing the fusion metal deposited on the surface of the semiconductor laser 102 while applying heat and melting it. At this time, the light emitting surface of the semiconductor laser 102 and the pedestal 1
04 Die bond so that the central xy planes match.

After that, wire bonding is performed between the semiconductor laser 102 and the terminals provided on the package to complete the semiconductor laser 10.
2 can be driven.

The four photodiodes 105A, 105B, 105C, and 105D, which serve as photoelectric conversion elements, are mounted on the substrate 106A, respectively.
, photodiodes 105C and 105D are mounted on the substrate 106B.
is formed. Further, alignment marks 107A and 107B are formed on the substrates 106A and 106B, respectively.

When mounting the substrates 106A and 106B, the semiconductor laser 102 is driven to emit light. While viewing the monitor screen of the mounting apparatus, the light emitting point 101 is aligned with the intersection of the reference line 108 (indicated by a broken line in FIG. 1A) 109 on the screen and the reference line 109. At this time, the mounting surface of the semiconductor laser 102 and the reference line 108 are made parallel to each other. Next, the alignment mark 107A on the board 106A and the reference line 11 on the screen.
The substrate 106A is rotated or moved so that 0 and 108 coincide, and die-bonded to the pedestal 104 from the z-axis direction. Further, the substrate 106B is also die-bonded in the same manner.

[0015] By simply aligning the alignment marks on the board with the reference line drawn in advance on the monitor screen of the mounting equipment, the four band-shaped photodiodes can be arranged radially with their long axes centered around the optical axis. , xy from the light emitting point
Distances on the plane are also implemented very precisely. Further, in this embodiment, a reference line is drawn on the monitor screen, but any other figure may be used as long as it has the same effect.

FIG. 2 is a perspective view showing a package after mounting according to an embodiment of the present invention. In this way, the semiconductor laser 102,
and substrates 106A and 106B with photodiodes.
After mounting, wire bond the electrodes and terminals of each element. Furthermore, polarizing plates are used as analyzers on the substrates 106A and 106B.
The optical element is completed by arranging an astigmatism generating means consisting of a condensing lens and non-uniformly periodic diffracted photons.

The optical element manufactured in this manner can constitute an extremely compact optical head because the only optical component necessary for detecting the optical signal and error signal is a diffraction means.

[0018]

As described above, according to the present invention, the photoelectric conversion element can be mounted with extremely high positional accuracy relative to the light source. In such optical devices mounted in the same package, the area of the photoelectric conversion device is small, and the position cannot be adjusted after manufacturing. Therefore, the permissible range for positional deviation during mounting is tight, but the present invention allows easy alignment by simply aligning the reference line in the magnified field of view of the mounting device with the alignment mark on the substrate on which the photoelectric conversion element is formed. Can be mounted with high positional accuracy.

[Brief explanation of drawings]

FIG. 1: Front view (a) of an optical element in an example of the present invention.
and a top view (b).

FIG. 2 is a perspective view showing a package after mounting in an embodiment of the present invention.

[Explanation of symbols]

101 Light emitting point 102 Semiconductor laser 103 Submount 104 Pedestal 105A, 105B, 105C, 105D Photodiode 106A, 106B Substrate 107A, 107B Alignment mark

Claims (3)

[Claims] Claim 1: An astigmatic aberration generating device comprising a diffraction means consisting of two unequal periodic diffraction grating regions that divides light from an optical storage medium in the directions of four photoelectric conversion elements, and the diffraction means and a condensing lens. an optical element having a light source, four band-shaped photoelectric conversion elements whose long axis directions are arranged radially around the optical axis of zero-order diffracted light of the diffraction means, and a light source,
An optical element characterized in that an alignment mark is provided on a substrate on which two of the four photoelectric conversion elements are formed, each of which is arranged at the same position in the optical axis direction. 2. The optical element according to claim 1, wherein the alignment mark consists of a straight line parallel to the mounting surface of the light source and a straight line perpendicular to the parallel straight line. 3. When mounting the photoelectric conversion element, a reference line or mark in the field of view of a magnifying observation means of a mounting device;
2. The method of mounting an optical device according to claim 1, wherein the mounting is performed after aligning the light emitting point of the light source and the alignment mark.