JP3178152B2 - Semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device of a mold type in which a laser diode element is formed by resin sealing, and more particularly to a semiconductor laser device in which the irradiation position is prevented from being displaced by laser irradiation.

[0002]

2. Description of the Related Art As a conventional semiconductor laser device, FIG.
The laser diode element 1 as shown in FIG.
A can type is known in which a cap 63 with a glass window 64 is welded to a heat radiator 62 by soldering. FIG. 7 shows a front view (a) of the semiconductor laser device and a sectional view (b) of (a) cut along line bb. In this semiconductor laser device, a laser diode element 1 is attached to a radiator 62 projecting upward from a stem 61 via a photodiode 23 which is a submount layer that also functions as a radiator plate. A cap 63 with a window is attached to the stem 61 so as to cover and protect the laser diode element 1 attached to the radiator 62. And these radiators 6
2. The position of the photodiode 23 is, as shown in FIG. 7A, the center of the circular window 64 when viewed from the front, that is,
The center line 25 (hereinafter, the X-axis direction) in the horizontal direction (perpendicular to the main surface of the radiator 62) and the vertical direction (radiator 6)
The laser diode element 1 is adjusted so that the laser diode element 1 is installed at an intersection 27 of a center line 26 (hereinafter, Y direction) of the main surface of the laser diode 2 (in the horizontal direction).

On the other hand, in recent years, compared with the above-mentioned can type, a resin-sealed type (mold type) which is a semiconductor laser device having a lower manufacturing cost and a greater degree of freedom in shape.
Things are being developed. For the mold type semiconductor laser device, refer to JP-A-2-125687. The structure described below is employed therein. In this semiconductor laser device, as shown in a perspective view of FIG. 8, a laser diode element 1 is mounted on a submount layer 23, and the periphery is sealed with a sealing resin layer 11 such as a transparent epoxy resin. , The lead frame 20 and the gold wire 21. A resin-sealed type device is conventionally known as a light-emitting device having a low light density per unit area, such as an LED.

[0004] Such a resin-sealed type device is a type of device excellent in terms of manufacturing cost and freedom of shape. In addition, even when it is applied to a laser diode element having a high light density, the end face is destroyed. By forming the prevention layer, it is possible to prevent deterioration of characteristics due to optical damage. Regarding a laser device having an end surface destruction prevention layer formed thereon, Japanese Patent Application No. 2-302 filed by the present applicant has been disclosed.
258, an example of which is shown in FIGS. The laser diode element 1 shown in FIG.
An H structure (double heterojunction structure) laser diode element 1 having an n-type GaAs substrate 2 and an AlGa
N-type cladding layer 3 made of As (aluminum-gallium-arsenic), active layer 4, p-type cladding layer 5, and GaAs
A p-type cap layer 6 made of s (gallium-arsenic) is laminated, and an electrode 7 is selectively deposited on the surface side of the opening of the p-type cap layer 6, while a back electrode is formed on the back side of the GaAs substrate 2. 8 is attached. The light emitting end face 9 irradiated with the laser light is provided with an end face destruction prevention layer 10 made of an organic resin having a low light absorption coefficient and high heat resistance in the wavelength band of the laser light.

Then, as shown in FIG. 11, the laser diode element 1 is disposed on the leading end side of the lead frame at the center of the three lead frames 20 via a submount layer and a photodiode 23 used as a heat sink. A bonding wire such as a gold wire 21 is wired to each lead frame 20 from the photodiode 23 and the p-type cap layer 6. Further, the periphery of the laser diode element 1 and the like fixed to the lead frame 20 is sealed with a sealing resin 11 such as a transparent epoxy resin.
And a semiconductor laser device is formed.
As described above, a mold-type semiconductor laser device using the laser diode element 1 on which the end surface breakdown prevention layer 10 is formed realizes a semiconductor laser device which is inexpensive and has excellent durability.

[0006] In such a mold type semiconductor laser device, FIG.
As shown in (b)), the position of the laser diode element 1 is substantially at the center of the mold resin layer 11, that is, at the intersection of the X axis and the Y axis, as in the can type. 27. The center position 28 of the lead frame 20 has an offset 29 of a distance ΔX _{off from} the center 27 of the mold resin layer 11 from the thickness of the laser diode element 1, the photodiode 23, and the thickness of the lead frame 20.

[0007] These semiconductor laser devices are used by being incorporated in various optical systems. For example, the case of an optical disk pickup is shown in the optical system conceptual diagram of FIG. The beam from the laser diode element 1 as a light source passes through a diffraction grating 51, is reflected by a half mirror 52, changes its direction by 90 °, and is condensed on the surface of a disk 54 via an objective lens 53. The beam is separated into a main beam and a sub beam by passing through the diffraction grating 51. The sub beam is used for tracking servo.
The reflected light from the disk 54 passes through the same objective lens 53 again, passes through the half mirror 52, enters the photodetector 55, and is converted into an electric signal. FIG. 13 shows the inside of the photodetector 55.
As shown in (b), the photodiode is composed of six photodiodes A to F, and the main beam is incident on the four photodiodes A to D at the center. The beam undergoes astigmatism when passing through the half mirror 52, and the shape of the main beam changes as shown by the dotted line in FIG. 13B depending on the position of the photodiode.

Assuming that the outputs of the four central photodiodes are A, B, C, and D, (A + C)-(B + D) is 0.
The position of the objective lens 53 is adjusted by the focusing servo mechanism so that The center of gravity of a beam on a photodiode, which will be described later, is defined as follows. [X, Y] = [((A + B)-(C + D)) / (A + B + C + D), / ((A + D)-(B + C)) / (A + B + C + D))

[0009]

In such a mold type semiconductor laser device, a problem that has recently been raised is that when the laser device is operated continuously or when the operating environment temperature is changed, the laser light is emitted. The light emitting point which is the origin irradiated to the outside of the device may be displaced. FIG.
Shows the situation. This figure shows the amount of displacement in the X direction (the direction perpendicular to the lead frame surface) with respect to the operation time when the above-described mold type semiconductor laser device is operated at room temperature and with an operation current of 50 mA. FIG. As can be seen from this figure, the light-emitting point is displaced by 0.5 μm in the −X direction (+ in the X direction in the laser diode side and − in the lead frame side), that is, in the lead frame 20, in about 2 minutes after the laser is turned on. Then, the lamp returns to the position before lighting in about 2 minutes after the light is turned off. Further, when this semiconductor laser device was incorporated in the above-mentioned optical pickup, it was found that the center of gravity of the beam on the photodiode fluctuated greatly due to the lighting of the semiconductor laser device or a change in environmental temperature.

For example, in an environment of -10 to 60 ° C., light output 3
When the experiment was conducted at mW, the center of gravity of the beam on the photo diode showed a fluctuation of 10 μm or more at the maximum. Thus, in the mold type semiconductor laser device having many excellent surfaces, the displacement of the light emitting point is suppressed in order to obtain the same performance as the can type laser device in terms of the accuracy of the light emitting point. This is very important.

FIG. 15 shows a model simulating the effect of displacement of a light emitting point during operation when a semiconductor laser device is used for a compact disk, for example. The simulation was performed using a one-dimensional system in which the laser beam reflected by the disk 73 via the convex lens 79 located at the distance d1 from the laser diode LD1 at the left end in the drawing was again converged on the photodiode FD69 via the convex lens 80. At this time, this one-dimensional system is treated as a double Fourier transform optical system, and the light intensity at the convex lens 79 when the light intensity distribution U1 in the laser diode element 1 is a rectangular shape having a center ΔX and a width of 2 μm according to the Fresnel diffraction formula. Distribution U2, light intensity distribution U on the disk surface 73
3. The complex amplitude U4 of the convex lens 80 and the light intensity distribution U5 + Δ of the photodiode 69 were obtained. ΔX corresponds to the displacement of the light emitting point of the laser diode. For example, FIG. 16 shows a result when the calculation parameters are shown in Table 1.

FIG. 16A shows the light intensity distributions U1, U2, U3, U4, U5 + Δ when the displacement ΔX of the light emitting point is 0, and FIG. 16B shows the displacement when ΔX is 1 μm. Further, the center of the beam spot on the photodiode can be calculated from the light intensity distribution (U5 + Δ) on the photodiode. For example, when the displacement ΔX of the light emitting point is 1 μm, the amount of movement of the center of the beam spot on the photodiode is calculated. Is -7.9 μm
become. Similar calculations were also performed for different ΔX, and the relationship between the displacement of the light emitting point and the displacement of the center of gravity of the beam spot on the photodiode was determined (FIG. 17). That is, in this pickup optical system, the displacement ΔX of the light emitting point is
On the photodiode, it is enlarged by 7.9 times. This value is defined as a coupling magnification M between the semiconductor laser element and the photodiode. The coupling magnification M is determined by the magnification of the lens system and the optical distance between the light emitting point of the semiconductor laser element of the optical pickup device and the multi-division photodiode for signal detection. Therefore, the coupling magnification M takes a different value depending on the configuration of the optical pickup.

ΔX 1.0 μm d1 25.0 mm f 3.9 mm Symbol: see FIG. 15 d2 4.6 mm Lens diameter 4.0 mm Δ0.3 mm In the conventional mold type semiconductor laser device, A mechanism for adjusting the displacement of the light emitting point because the variation amount of the beam spot is equal to or larger than the allowable value,
Alternatively, a mechanism that can follow the center of gravity of the beam spot is required. As described above, the conventional mold-type semiconductor laser device is inexpensive and can be easily manufactured in various shapes. However, when used in a device that requires the accuracy of the light emitting point, extra accuracy is required depending on the accuracy. Therefore, it is difficult to utilize the advantages of the mold type.

The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide a mold type.
It is an object of the present invention to provide a semiconductor laser device which has a small displacement of a light emitting point and can be used as it is in a device requiring high precision such as an optical system of a pickup section of a compact disc.

[0015]

According to the present invention, a laser diode element having at least a front emission end face capable of emitting laser light to the outside is formed in a flat plate-like shape via a support substrate. A semiconductor laser device having a lead frame supported and controlled on a main part surface of the semiconductor laser, and a sealing resin layer for sealing at least the laser diode element on the lead frame with the resin capable of transmitting the laser light; Assuming the main frame section parallel to the front emission end face in the lead frame, further defining the longitudinal direction of the cross section of the lead frame as a horizontal direction, a horizontal center line defining the center of the cross section, and a vertical axis defining a vertical center. When assuming a center line, the sealing resin layer is aligned with the horizontal center line portion and the vertical center line in the cross section of the lead frame. It was assumed to be symmetric resin layer formed symmetrically.

Further, according to the present invention, there is provided a lead frame for supporting and controlling a laser diode element having at least a front emission end face capable of emitting laser light to the outside on a flat main surface via a support substrate. A sealing resin layer for sealing at least the laser diode element on the lead frame with the resin capable of transmitting the laser beam; the main part being parallel to the front emission end face of the lead frame. Assuming a cross-section, furthermore, assuming that the longitudinal direction of this lead frame cross-section is a horizontal direction, and a horizontal center line defining the center of the cross-section and a vertical center line defining a vertical center,
The sealing resin layer is formed symmetrically with respect to the horizontal center line and the vertical center line; the sealing resin layer is a symmetrical resin layer formed with the lead frame as a center of symmetry. I do.

Further, according to the present invention, there is provided a lead frame for supporting and controlling a laser diode element having at least a front emission end face capable of emitting laser light to the outside on a flat main surface via a support substrate. A sealing resin layer for sealing at least the laser diode element on the lead frame with the resin capable of transmitting the laser light; a lead frame portion to be mounted on an external substrate is exposed from the sealing resin. A semiconductor laser device that exposes the lead frame surface on the side opposite to the element mounting surface side on which the laser diode element is mounted to a substrate mounting surface to an external substrate from a sealing resin; Is fixed to the external substrate. Here, it is good that the penetrations holes are provided in Ridofure over arm portions that are exposed from the sealing resin as a means for fixing the semiconductor laser device to the external substrate. Preferably, the means for fixing the semiconductor laser device to the external substrate is an adhesive. Preferably, the means for fixing the semiconductor laser device to the external substrate has a connection means passing through the through hole.

[0018]

Various causes can be considered for the displacement of the light emitting point from the laser diode element, which is the subject of the present invention. However, these inventors disclose the heat of the sealing resin caused by the heat generated during the operation of the laser diode element. Attention was paid to expansion. In relation to the sealing resin, the displacement of the lead frame due to the thermal expansion of the sealing resin is minimized with respect to the lead frame most susceptible to the thermal expansion of the sealing resin. The displacement is suppressed.

First, by using a symmetrical resin layer with the lead frame as the center of symmetry as the sealing resin layer, it is possible to equalize the stress caused by the thermal expansion of the sealing resin layer from before, after, and right and left of the lead frame. Therefore, distortion or the like of the lead frame due to a difference in thermal stress due to thermal expansion can be suppressed, and as a result, displacement of a light emitting point of the laser diode element can be suppressed.

Also, by fixing the lead frame itself to the external substrate, it is possible to eliminate the influence of the thermal expansion of the sealing resin layer and suppress the light emitting point displacement. As such a lead frame fixing means, fixing the exposed surface of the lead frame to an external substrate as a substrate mounting surface can be adopted. When the substrate mounting surface is an exposed surface of the lead frame, heat generated during operation of the laser diode element can be radiated from the substrate mounting surface to the external substrate, so that the thermal expansion of the sealing resin layer Can be reduced, and the influence of the sealing resin layer can be reduced.

Further, as a lead frame fixing means,
Using a through-fixing means having at least one through-hole formed in the lead frame exposed from the sealing resin, and connecting the lead frame and the external substrate with a solid or liquid coupling means having a small coefficient of thermal expansion from this fixing hole. Is fixed, the displacement of the light emitting point of the laser diode can be suppressed.

Further, the thickness of the sealing resin layer, that is, the separation distance that is a distance from an external substrate or the like is set so that the amount of movement of the lead frame falls within an allowable range based on the thermal expansion coefficient of the sealing resin. Accordingly, the displacement of the light emitting point can be suppressed.

[0023]

[Example 1]

FIG. 1 illustrates a configuration of a semiconductor laser device according to the first embodiment ((a) is a cross-sectional view along the X axis 25, and (b) is a bb cross-sectional view of (a)). The apparatus of the present example is described first with reference to FIG.
This is an example in which the present invention is applied to the mold type semiconductor laser device described based on FIG. 10, in which the laser diode element 1 having the end face destruction prevention layer 10 as shown in FIG. The laser diode element 1 and the photodiode 23 are fixed to a lead frame 20 that supports and controls the laser diode element 1 and the photodiode 23. The periphery of the laser diode element 1 and the like fixed to the lead frame 20 is sealed with a sealing resin 11 such as a transparent epoxy resin. Therefore, the same reference numerals are given to the portions common to the conventional device, and the description is omitted.

In this embodiment, it should be noted that the sealing resin layer 11 has a horizontal (perpendicular to the lead frame surface) center line 25 (hereinafter referred to as the X-axis direction) and a vertical direction (parallel to the lead frame surface). Intersection 2 of center line 26 (hereinafter, Y direction)
7 and the center position 28 of the lead frame 20 match. That is, the center 27 of the sealing resin layer 11 existing in the conventional device and the lead frame 20
Offset 29 from the center position 28 does not exist. More specifically, in the section bb of the lead frame 20 parallel to the front emission end face on which the end face destruction prevention layer 10 of the laser diode element 1 is formed, the Y axis 26 defining the vertical direction and the horizontal direction are defined. X axis 2
5 coincides with the horizontal and vertical center axes of the sealing resin layer 11,
The X-axis 25 and the Y-axis 26 are symmetrically set so that the sealing resin layer 11
Are formed. Therefore, in the device of this example, the sealing resin layers 11 existing on the front, rear,
Are symmetric. Therefore, the thermal stress from the sealing resin layer 11 to the lead frame 20 due to the heat generated at the time of laser emission is balanced and relatively canceled. Therefore, the change in the position of the lead frame 20 can be limited to the change caused by the shape of the lead frame 20, the photodiode 23 fixed to the lead frame 20, the laser diode 1, and the like. For this reason, the fluctuation of the lead frame 20 can be greatly reduced as compared with the conventional device, and the displacement of the light emitting point from the laser diode 1 fixed to the lead frame 20 can be suppressed. Note that the center position 28 of the lead frame 20 is
, The position of the laser diode 1 is deviated from the center 27 of the sealing resin layer 11.

However, since the optical properties of the sealing resin layer 11 do not change between the center 27 and the periphery thereof, the performance of the emitted laser does not change. As described above, since the displacement of the light emitting point is caused by the difference in the thermal expansion coefficient between the resin and the lead frame due to the heat generated during the laser emission, the symmetrical sealing resin layer referred to here substantially corresponds to the lead. The shape of the resin layer may be in a range that affects the frame. For example, the outer shape of the resin, which is considered to have little effect on the lead frame, is not limited to the symmetrical shape.

FIG. 2 shows the result of measuring the displacement of the laser emission point using the apparatus of this embodiment, in comparison with the conventional apparatus. In this measurement, as in the conventional case, the semiconductor laser device of this example was operated at room temperature at an operation current of 50 mA, and the displacement amount in the X direction was shown with respect to the operation time.
As can be seen from this figure, in the conventional device, the light emitting point is displaced by 0.5 μm in the −X direction, that is, toward the lead frame 20 side, in about 2 minutes after the laser is turned on. Shows almost no displacement of the light emitting point,
It is within 5 μm. Therefore, the displacement of the light emitting point is suppressed by aligning the center position 28 of the lead frame 20 with the center 27 of the sealing resin layer 11 as in the device of the present example. When the element of this embodiment is used for an optical pickup, the movement of the beam spot on the photodiode can be suppressed as shown in the example of FIG.

As described above, by forming the sealing resin layer 11 having a shape symmetrical with respect to the center lines 25 and 26 of the lead frame 20, the influence on the thermal expansion of the sealing resin layer 11 received by the lead frame 20 is obtained. Can be eliminated, and the displacement of the light emitting point of the laser beam can be suppressed. Although the present embodiment is described based on a cylindrical mold type semiconductor laser device, a mold type semiconductor laser device such as a flat type as shown in FIG. Of course, if the shape is substantially symmetric with respect to the range that is greatly affected by the heat generation near the lead frame 20, the same effect can be obtained. In the flat-type semiconductor laser device shown in FIG. 3, except for the shape of the sealing resin layer 11,
Since it has the same configuration as the semiconductor laser device described above,
The same reference numerals are given and the description is omitted.

Further, in this embodiment, the case where the cross-sectional shape of the lead frame is rectangular is described, but other shapes may be used as long as the technical idea of the present invention is followed. In particular, even when the horizontal and vertical centerlines cannot be strictly defined, a horizontal centerline substantially parallel to the main surface and passing through the center of gravity and a centerline perpendicular to the horizontal centerline may be used. Embodiment 2 FIG. 4 shows the structure of a semiconductor laser device according to Embodiment 2 of the present invention. The device of the present embodiment is also a mold type semiconductor laser device similar to that of the first embodiment, and the laser diode element 1 on which the end face destruction prevention layer is formed is connected via the photodiode 23 used as a submount layer and a heat sink. The laser diode element 1 and the photodiode 23 are supported on a lead frame 20 for supporting and controlling the device, and are fixed on the main surface. Therefore, portions common to those of the apparatus of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The point to be noted in this embodiment is that the sealing resin layer 11 is provided on the laser diode element mounting surface 20 of the lead frame 20 on which the laser diode element 1 is mounted.
The surface 20b on the opposite side facing a is an exposed surface. That is, in the device of this example, the sealing resin layer 11 is formed so as to cover the laser diode element 1 and the photodiode 23 from the mounting surface 20a of the lead frame 20, and faces the mounting surface 20a of the lead frame 20. The opposite surface 20b is an exposed surface on which the sealing resin layer 11 is not formed. Therefore, as shown in FIG. 4, the semiconductor laser device can be fixed to the fixed substrate 35 using the exposed surface 20b.
The fixing method is such that an adhesive 33 is provided between the exposed surface 20b and the fixed substrate 35.
Or a method using a fixing through hole of a lead frame as described in the third embodiment. In such an apparatus, the exposed surface 20b is
Therefore, there is no change in the position from the fixed substrate 35.

Further, the sealing resin layer 11 is also formed on the lead frame 2.
0, that is, only on the mounting surface 20 a, the thermal expansion of the sealing resin layer 11 does not affect the lead frame 20. Therefore, in the device of this example, even if the temperature of the sealing resin layer 11 increases during emission of the laser beam, the lead frame 20 does not change. For this reason, displacement of the light emitting point of the laser diode element 1 supported by the lead frame 20 can also be suppressed. This effect was measured under the same conditions as in Example 1, and the same measured values as those measured in Example 1 and shown in FIG. 2 were obtained.

Although the present embodiment has been described based on a mold type semiconductor laser device having a rectangular sealing resin layer 11, it is sufficient that the exposed surface 20b of the lead frame is formed. Even in the case of a semiconductor laser device in which the resin layer has various shapes such as a semicircle, FIG.
8, the sealing resin layer 11 may cover only the vicinity of the laser diode element 1 and the photodiode 23 as shown in FIG. In any case, the bonding is performed to the external fixed substrate 35 with the adhesive 33. In particular, FIG. 22 shows a structure in which only a part of the lead frame is exposed from the resin in order to fix the laser device to the external substrate by bonding, and is characterized in that it is highly practical in this respect.

FIG. 23 shows this perspective view. The fixing method in this case may be a method of bonding and fixing using the exposed surface of the lead frame. FIG. 19 shows an example of fixing means according to the present invention including this example. (A) is an example in which the main surface of the lead frame 20 is resin-sealed with the same width, and the exposed surface 20b on the opposite side of the tard frame is fixed on the fixed substrate 35 with an adhesive 33. An example in which the width of 20 is larger than the width of the sealing resin to increase the bonding surface,
(C) is an example in which the same laser diode device as in (b) is used using an adhesive and a mounting jig 331, and (d) is a fixed substrate 35 using the lead frame portion exposed from the sealing resin.
(E) is fixed using an adhesive 33 to (b),
An example in which the same device as in (c) is mounted by fitting an exposed portion of the lead frame 20 into a corresponding recess provided in the fixed substrate 35 is shown. Furthermore, by using the exposed surface 20b and the fixed substrate 35 having good heat conduction so that heat is easily transmitted from the exposed surface 20b to the fixed substrate 35, heat during laser emission can be dissipated to the fixed substrate 35 side. It is desirable because the temperature rise of the sealing resin layer 11 can be reduced and the displacement of the light emitting point can be further suppressed. Third Embodiment FIG. 20 shows a configuration of a semiconductor laser device according to a third embodiment of the present invention. The device of the present embodiment is also a mold type semiconductor laser device similar to the above embodiment, and the laser diode element 1 on which the end face destruction prevention layer is formed is:
This device is fixed to a lead frame 20 that supports and controls the laser diode element 1 and the photodiode 23 via a photodiode 23, and the periphery thereof is sealed with a sealing resin layer 11. Therefore, the first embodiment
The same reference numerals are given to the same parts as those of the above-mentioned device, and the description is omitted.

A point to be noted in this embodiment is that a through hole 30 for fixing the lead frame 20 is formed. In the device of the present example, this through hole 3
2 are formed on the lead frame 20 below the laser diode element 1 so that both ends thereof can be fixed. Examples of the fixing means having this structure are shown in FIGS.
Shown in In this example, the lead frame 20 is fixed by the bolts 32, but has a relatively low coefficient of thermal expansion.
Of course, it is also possible to fix using a fluid metal or resin such as solder having good heat conductivity.

The displacement of the light emitting point of the laser beam in the apparatus of this embodiment is measured under the same conditions as in the first embodiment, and is substantially the same as the result measured in the first embodiment and shown in FIG. It has been confirmed that the displacement is within the displacement. In addition,
Although the above example is described based on a semiconductor laser device having a rectangular sealing resin layer 11, in this example, the through holes 3 that can be fixed to the fixed substrate 35 are formed in the lead frame 20.
0 may be prepared, and a device in which the shape of the sealing resin layer 11 is asymmetric may be used. Reference Example FIG. 5 shows a configuration of a semiconductor laser device according to a reference example of the present invention. The device of this embodiment is also a semiconductor laser device of a mold type similar to that of the above-described embodiment, and the laser diode device 1 on which the end face destruction prevention layer is formed is connected to the laser diode device 1 and the photo diode via a photodiode 23. The diode 23 is fixed to a lead frame 20 for supporting and controlling the diode 23, and the periphery thereof is sealed with a sealing resin layer 1.
1 is a device sealed by the same. Therefore, portions common to those of the apparatus of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

A point to be noted in the apparatus of this embodiment is that, of the outer surface of the sealing resin layer 11, a resin outer surface 40 covering a surface 20b opposite to the mounting surface 20a on which the laser diode element 1 is mounted on the lead frame 20. Is a mounting surface 40 that is fixed to a planar external fixed substrate via an adhesive 33. Then, the separation distance ΔX ₁ between the mounting surface 40 and the surface 20b is kept constant.

As described above, in the simulation of the optical pickup optical system, when the light emitting point position has the displacement amount ΔX as shown in FIG. 16, the beam spot fluctuates largely on the photodiode, which is not preferable. Therefore, the separation distance is ΔX ₁ mm, and the linear expansion coefficient of the sealing resin layer is α /
° C, the change in the operating environment temperature of the laser diode element is Δ
When T ° C., the separation distance ΔX ₁ mm is set to a value that satisfies the following equation (1).

[0037]

ΔL / M ΔX ₁ ≦ ─────── (1) α · ΔT [On a multi-segment photodiode for signal detection of an optical pickup device using a semiconductor laser as a light source for reproduction of an optical disk system. The maximum allowable amount of the beam spot variation is ΔLmm, the magnification of the lens system including at least one lens system between the light emitting point of the semiconductor laser element of the optical pickup device and the multi-division photodiode for signal detection, and the light emitting point of the semiconductor laser element. And M is the imaging magnification defined by the optical distance between the multi-segment photodiode for signal detection and the signal detection.] When a transparent epoxy resin is used as the sealing resin material according to the present invention, its linear expansion coefficient α
Is 5 to 7 × 10 ⁻⁵ / ° C. For example, the allowable amount ΔL of the beam spot movement when the temperature change ΔT in the use environment is −10 to 60 ° C. is 10 μm, the imaging magnification M between the light emitting point and the photodiode is 8 times, and the linear expansion coefficient α is 6 × 10 ⁻⁵ / In the case of ° C., it is necessary to satisfy ΔX ₁ ≦ 0.2 mm from the above equation (1). M and ΔL change depending on the optical system used, and the use environment temperature change ΔT also changes depending on the standard. However, it goes without saying that ΔX ₁ is determined by the above equation (1).

Therefore, by fixing the device of this embodiment so that the mounting surface 40 is in close contact with the fixed substrate 35, the fixed substrate 3
5, the displacement of the lead frame 20 from the distance ΔX ₁
In the range of the effect of the sealing resin layer 11 described above. As described above, in any of the semiconductor laser devices described in the above embodiments, any of the devices satisfies the allowable value of the beam spot movement amount on the photodiode that can be used as it is as a pickup for a compact disk. . Therefore, by the mold type semiconductor laser device as described above, at low cost, a semiconductor laser device that can be easily manufactured in a free shape,
Further, it is possible to realize a semiconductor laser device in which the accuracy of the light emitting point is superior to that of the can type.

[0039]

As described above, in the semiconductor laser device according to the present invention, the thickness of the sealing resin layer symmetrical to the lead frame, the lead frame that can be fixed to an external fixed substrate or the like, and the thickness of the sealing resin layer are reduced. By using means such as a specified mounting surface, displacement of the lead frame due to thermal expansion of the sealing resin layer can be suppressed. Therefore, the displacement of the laser diode element fixed on the lead frame during operation can be suppressed, and the displacement of the light emitting point can be greatly reduced. For this reason, in a mold-type semiconductor laser device that can easily adopt various element shapes at low cost, it is possible to realize a highly accurate device with little displacement of a light emitting point.

Therefore, according to the present invention, even in a semiconductor laser device of a mold type, an extra mechanism such as a position compensation mechanism is required for a device that requires high-precision stability of a light emitting point, such as a compact disk pickup. A semiconductor laser device that can be adopted as it is can be realized without using. A mold-type semiconductor laser device as in this example is inexpensive and can easily realize various shapes, and thus has been adopted in various devices in recent years.
Further, according to the present invention, it is possible to provide a semiconductor laser device having extremely high stability of positional accuracy of a light emitting point, and it is possible to use the semiconductor laser device in a wide range of devices.

[Brief description of the drawings]

1A is a side view showing a configuration of a semiconductor laser device according to a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line bb of FIG.

FIG. 2 is a graph showing a state of displacement of a light emitting point of the semiconductor laser device shown in FIG. 1 together with a displacement of a light emitting point of a conventional semiconductor laser device.

FIG. 3 is a transparent perspective view showing a configuration of a semiconductor laser device having a rectangular outer shape manufactured based on the same technology as the semiconductor laser device shown in FIG. 1;

4A is a side view showing a configuration of a semiconductor laser device according to a second embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along line bb of FIG.

5A is a side view showing a configuration of a semiconductor laser device according to a reference example of the present invention, and FIG. 5B is a cross-sectional view taken along line bb of FIG.

FIG. 6 is a perspective view showing a configuration of a conventional can-type semiconductor laser device with a part thereof being omitted.

7A is a front view showing the configuration of the semiconductor laser device shown in FIG. 6, and FIG. 7B is a cross-sectional view taken along line bb of FIG.

FIG. 8 is a perspective view showing the configuration of a semiconductor laser device of a mold type.

9 is a perspective view showing a configuration of a laser diode element used in the semiconductor laser device shown in FIG.

FIG. 10 shows a─a of the laser diode element shown in FIG.
It is sectional drawing.

FIG. 11 is a sectional view showing a configuration of a mold type semiconductor laser device.

12A is a front view showing the configuration of the semiconductor laser device shown in FIG. 8, and FIG. 12B is a cross-sectional view taken along line bb of FIG.

FIG. 13 is a conceptual diagram of an optical system of an optical disk pickup and a configuration diagram of a photodetector.

FIG. 14 is a graph showing a displacement of a light emitting point in the semiconductor laser device shown in FIG. 8;

FIG. 15 is an explanatory view showing an outline of a one-dimensional simulation for examining the effect of displacement of a light emitting point in a compact disk pickup device.

FIG. 16 is a graph showing the results of the simulation shown in FIG.

FIG. 17 is a graph showing the results of the simulation shown in FIG.

FIGS. 18A and 18B are side views (a) and (b) a cross-sectional view (b) of FIG. 18 (a) illustrating a configuration in which the sealing resin layer covers only the vicinity of the laser diode element and the photodiode according to the second embodiment. .

FIG. 19 is a sectional view (a), a sectional view (b), a sectional view (c), showing an example of fixing the semiconductor laser device shown in FIG.
It is sectional drawing (d) and sectional drawing (e).

FIGS. 20A and 20B are side views (a) and (b) a cross-sectional view (b) showing a configuration in which the sealing resin layer covers only the vicinity of the laser diode element and the photodiode according to the third embodiment. .

21A and 21B are a sectional view and a sectional view showing an example of fixing the semiconductor laser device of FIG.

FIG. 22 is a cross-sectional view illustrating a configuration when a lead frame is exposed by a sealing resin according to the second embodiment.

FIG. 23 is a perspective view of a case where the lead frame according to the second embodiment is exposed by a sealing resin.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser diode element, 2 ... Substrate, 3 ... N-type cladding layer, 4 ... Active layer, 5 ... P-type cladding layer, 6 ... Cap layer, 7 ... Electrode, 8 ... Back electrode, 9 ... Light emitting end face, 10 ...
End face destruction prevention layer, 11: sealing resin layer, 20: lead frame, 21: gold wire, 23: photodiode (supporting substrate), 25: horizontal center line (X-axis direction), 26
... vertical center line (Y-axis direction), 27 ... intersection, 28 ...
Lead frame center, 29 ... offset, 30 ...
Fixing holes, 31: conduction holes, 32: bolts, 35: fixed substrate, 40: mounting surface, 51: diffraction grating, 52: half mirror, 33: adhesive, 53: objective lens, 54: disk, 55: light Detector, 61: Stem, 62: Heat radiator, 6
3 cap, 64 glass window, 69 photodiode, 73 disk, 79 convex lens, 80 convex lens

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-209786 (JP, A) JP-A-5-129731 (JP, A) JP-A-64-28882 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (6)

(57) [Claims] 1. A lead frame for supporting and controlling a laser diode element having at least a front emission end face capable of emitting laser light to the outside on a flat main surface through a support substrate, and transmitting the laser light. A sealing resin layer for sealing at least the laser diode element on the lead frame with a possible resin; assuming the main part cross section parallel to the front emission end face in the lead frame; When the longitudinal direction of the cross section of the lead frame is the horizontal direction, and the horizontal center line defining the center of the cross section and the vertical center line defining the vertical center are assumed, the sealing resin layer is A symmetrical resin layer formed symmetrically with respect to the horizontal center line portion and the vertical center line in the semiconductor Laser equipment. 2. A lead frame for supporting and controlling a laser diode element having at least a front emission end face capable of emitting laser light to the outside on a flat main surface via a support substrate, and transmitting the laser light. A sealing resin layer for sealing at least the laser diode element on the lead frame with a possible resin; assuming the main part cross section parallel to the front emission end face in the lead frame; Assuming that the longitudinal direction of the lead frame cross section is the horizontal direction, and assuming a horizontal center line defining the center of the cross section and a vertical center line defining the vertical center, the sealing resin layer has the horizontal center line. And the sealing resin layer is formed symmetrically with respect to the vertical center line; The semiconductor laser device, characterized in that the a symmetric resin layer. 3. A lead frame for supporting and controlling a laser diode element having at least a front emission end face capable of emitting laser light to the outside on a main surface of a flat plate via a support substrate, and transmitting the laser light. A sealing resin layer for sealing at least the laser diode element on the lead frame by a possible resin; a semiconductor device having a lead frame portion mounted on an external substrate exposed from the sealing resin; The semiconductor laser device is fixed to the external substrate by exposing the lead frame surface on the side opposite to the element mounting surface side on which the laser diode element is mounted to a substrate mounting surface to an external substrate from the sealing resin. 1. A semiconductor laser device comprising: 4. The semiconductor laser device according to claim 3, wherein:
The semiconductor laser device, wherein a penetrations holes are provided a semiconductor laser device in the Ridofure over arm portions that are exposed from the sealing resin as a means for fixing the external substrate. 5. The semiconductor laser device according to claim 3, wherein the means for fixing the semiconductor laser device to the external substrate is an adhesive. 6. The semiconductor laser device according to claim 4, wherein:
A semiconductor laser device, wherein the means for fixing the semiconductor laser device to the external substrate has a connection means passing through the through hole.