JP2001291812A - Molded semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded semiconductor laser wherein the top and bottom can be easily discriminated when a molded semiconductor laser in which leads are exposed from the bottom surface is built in a cylindrical holder, and assembling is enabled without troublesome work such as recognition of direction in imperfect assembling or an assembling step. SOLUTION: A submount 7 in which a laser chip 8 and a photodetector 5 for monitoring are arranged is bonded to a die pad 2a of a first lead 2. Electrodes of the laser chip 8 and the photodetector 5 are connected electrically with second leads 3 and 4, respectively, by using wires which are not shown in figure. One end portion in the first and second leads 2-4 is held collectively with a frame body 6 of resin. The first and second leads 2-4 are stretched from the frame body 6 in such a manner that arrangement of the other end portions of the plural leads which are led out from the frame body 6 and stretched becomes asymmetric with respect to the center point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CD (compact disk), a DVD (digital video disk), an LB
The present invention relates to a semiconductor laser particularly suitable for use as a light source for pickup such as P (laser beam printer) and DVD-ROM. More specifically, the present invention relates to a molded semiconductor laser having a structure in which a laser chip is die-bonded to a lead frame and its periphery is protected by a frame formed by resin molding.

[0002]

2. Description of the Related Art A mold type semiconductor laser is disclosed in, for example, Japanese Patent No. 2951077 and has a structure as shown in FIG. 5, in which each lead is cut off from a lead frame 1 and put into an antistatic tray. It is carried into the assembly process. In FIG. 5, a laser (LD) chip 8 is attached to a die pad portion 2a at the tip of the common lead 2 among three leads 2, 3, and 4 integrally formed as a lead frame 1.
Is mounted. The LD chip 8 and the monitor light receiving element 5 are wire-bonded to other leads 3 and 4 by wires (not shown). Then, as shown in FIG. 5, for example, transfer molding is performed with a synthetic resin, and a frame 6 is formed therearound, thereby being integrated with each of the leads 2, 3, and 4 and separated from the lead frame 1. Also, the leads 2 to 4 are fixed.

When this semiconductor laser is used as a pickup device, it is attached to the optical axis of a collimator lens or a finite objective lens. In particular, in the case of a pickup using a diffraction grating, a cylindrical holder 21 is generally used as shown in FIG. 6 (a) to facilitate coaxial alignment with the diffraction grating and the lens system.
The diffraction grating 22 is fixed to the cylindrical holder 21, and the molded semiconductor laser 10 is inserted from one end of the cylindrical holder 21. Each lead of the semiconductor laser 10 incorporated in the cylindrical holder 21 is inserted into, for example, a through hole of a flexible substrate (not shown), soldered, and axially aligned with the above-described lens system. In addition,
The diffraction grating 22 may be turned upside down, but if it is turned sideways, the direction of the diffraction grating 22 changes and cannot be used, so it is formed in a diamond shape so as not to be turned sideways.

[0004]

As described above, in a molded semiconductor laser, a plurality of leads are integrated by a synthetic resin frame, and the LD chip portion is protected. As shown in FIG. 5, there is a case where the upper surface side is not covered or the upper surface side except for the light emitting surface is molded with a resin.

However, when the semiconductor laser is inserted into the cylindrical holder as described above, the visible portion of the semiconductor laser is
As shown in (b), it is impossible to distinguish between the upper and lower parts simply because the leads protrude from the rectangular bottom part at equal intervals.
As described above, there is no distinction between the upper and lower sides of the diffraction grating, and the upper and lower sides of the semiconductor laser may be inverted. The lead of the chip and the lead of the light receiving element for monitoring are reversed, so that it is impossible to connect an appropriate power supply, and there is a problem that an upside down defective product is likely to occur during the assembly process. On the other hand, the size of the bottom surface of the semiconductor laser shown in FIG. 6B is, for example, 4 mm × 1.5.
mm, and there is no space for marking. In addition, if the cylindrical holder is marked, when assembling the semiconductor laser, it is necessary to assemble while paying attention to the vertical direction, and when assembling it on a flexible substrate, etc., the vertical position of the cylindrical holder must be checked. Efficiency decreases.

The present invention solves such a problem. Even if a molded semiconductor laser whose leads are led out from the bottom surface is incorporated in a cylindrical holder, the upper and lower portions thereof can be easily identified, and the orientation can be easily determined in a defective assembly or an assembly stage. It is an object of the present invention to provide a molded semiconductor laser which can be assembled without performing a troublesome operation such as confirmation.

[0007]

A molded semiconductor laser according to the present invention comprises a first lead having a die pad formed at one end, a laser chip bonded to the die pad, and an electrode of the laser chip. A second lead electrically connected thereto; and a resin frame body integrally holding one end sides of a plurality of leads including at least the first and second leads, and exposed from the frame body. The plurality of leads extend from the frame such that the arrangement of the other ends of the plurality of extending leads in a plane perpendicular to the leads is asymmetric with respect to a center point thereof.

Here, the term "center point" means the center of rotation when the upside down is reversed, and the asymmetric means that the same lead arrangement is not obtained when the upside down is reversed.

With this structure, if the position of the through hole of the flexible substrate or the like connected to the lead of the semiconductor laser is formed so as to match the position of the lead in the normal direction, if the direction of the semiconductor laser is reversed, It can be seen immediately that the direction is reversed without being inserted into the through hole of the flexible substrate. As a result, the assembling process is simplified, and the lead terminals of the laser chip and the light receiving element are not connected in reverse, and the components are not damaged.

[0010] The other end portion of the plurality of leads is formed by forming at least one of the plurality of leads so as to have a step with respect to the row of the other leads in or out of the frame. May be formed asymmetrically, and at least one of the plurality of leads may be formed in a shape different from the cross-sectional shape of the other lead, so that the other ends of the plurality of leads may be formed. The arrangement may be formed asymmetrically.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a molded semiconductor laser according to the present invention will be described with reference to the drawings. As shown in an explanatory view of one embodiment in FIG. 1, a mold type semiconductor laser according to the present invention has a laser on a die pad portion 2a of a first lead (common lead) 2 having a die pad portion 2a formed at one end. A submount 7 provided with a chip 8 and a light receiving element 5 for monitoring is bonded. The electrodes of the laser chip 8 and the light receiving element 5 are electrically connected to the second leads 3 and 4 by wires such as gold wires (not shown). One end side is integrally held by a resin frame 6. In the present invention, the first lead 2 and the first lead 2 are arranged such that the arrangement of the other ends of the plurality of leads extended from the frame 6 in the vertical plane with respect to the leads 2 to 4 is asymmetrical with respect to the center point. 2 leads 3 and 4 are frame 6
Extending from.

First lead 2 and second leads 3 and 4
As shown in FIG. 5 described above, in the assembling stage, one end is formed in a state of a lead frame connected by side rails, and one lead frame has several tens of semiconductor lasers. A set of leads is formed. However, in the state of the product, as shown in the explanatory views of the cross section and the bottom surface in FIGS. 1A and 1B, the leads are not arranged in a line, but in the example shown in FIG. When the lead 2 comes out of the frame 6, it is bent to provide a step. Therefore, the ends of each of the leads 2 to 4 are not aligned but are asymmetric with respect to the center point. The die pad portion 2a for bonding the submount 7 and the tips of the other leads 3, 4 need not necessarily be on the same plane, but a step may be provided at the other end 2e, 4e. .

In the example shown in FIG. 1, the first lead 2 is formed at a portion protruding from the resin frame 6, but as shown in FIG. May be formed. In this case, in the state of the lead frame, since the other end of each of the leads 2 to 4 is connected to the side rail as described above, forming with a step at the base of the side rail is performed.
It can be formed by cutting each lead in the state having the step.

The laser chip 8 has a double hetero structure of, for example, an AlGaAs or InGaAlP compound semiconductor similar to the conventional one, and is mounted on a silicon submount 7 or the like, and the silicon submount 7 is bonded to the die pad portion 2a of the common lead. Have been.
A light receiving element 5 for monitoring is formed on the submount 7 so that the output of the laser chip 8 can be automatically controlled, and one of the electrodes is a first (common) lead 2. The other electrodes are electrically connected to the second leads 3 and 4 by wires such as gold wires (not shown).

In the example shown in FIG. 1, as shown in the terminal connection diagram in FIG. 1 (d), the laser chip LD and the light receiving element PD are connected one by one, and one first lead is provided. The above-mentioned step is provided by forming three leads, two and two second leads 3 and 4, one of which is formed by the first lead 2.
However, as shown in FIG.
There is also a structure in which two D1 and LD2 and one light receiving element PD are provided. In this case, the total number of leads is four. Further, even when the laser chip LD and the light receiving element PD are provided one by one, as shown in the terminal connection diagram of FIG. 3C, both the laser chip and the light receiving element are not connected to the first lead. In some cases, leads are provided separately, and in this case also, there are four leads. Even when there are four such leads, for example, as shown in FIG. 3 (a), one or two of them may be formed so as to be asymmetric with respect to the center point.

In the example shown in FIG. 1, a chip type multilayer ceramic capacitor 9 is provided between a first lead 2 and a second lead 3 which is wire-bonded to a laser chip 8.
However, they are directly connected by soldering or the like without using leads or the like. This is to protect the laser chip from being destroyed even when a surge such as static electricity is applied through the lead. Therefore, it is necessary to discharge through the capacitor 9 before the surge reaches the laser chip, and an inductance is formed between the leads at a position as far as possible from the laser chip 8 and closest to the laser chip 8 to which the surge can be applied. It is preferable to be provided without the intermediary of the lead so as not to cause the generation of the lead. From this point,
It is preferable that the lead is directly attached between the leads led out of the frame body 6. By providing a step between the leads 2 and 3 according to the present invention, the interval between the leads 2 and 3 is increased, and the capacitor 9 is connected to the leads 2 and 3. Can be directly installed in the middle. Note that the multilayer ceramic capacitor 9 having a capacitance of 0.5 μF or more can effectively discharge a surge such as static electricity and is preferable for protecting the laser chip.

The mold type semiconductor laser according to the present invention comprises:
Since the ends of the leads derived from the resin frame 6 are formed so as to be asymmetrical with respect to the center point, for example, a portion exposed to the outside when inserted into the above-mentioned cylindrical holder is formed. Even when only the bottom portion of the semiconductor laser and the lead are provided, the orientation of the lead can be recognized at a glance because the arrangement of the lead is different when the lead is vertically inverted. Further, as shown in FIG. 1 (c), the through holes 12 to 14 of the flexible substrate for mounting the semiconductor laser are arranged on the flexible substrate 11 according to the arrangement of the lead ends of the semiconductor laser. By forming them, if the directions are reversed, the leads 2 to 4 of the semiconductor laser cannot be inserted into the through holes 12 to 14 of the flexible substrate 11, and they can be inserted without any doubt in the correct direction. Note that 1 in FIG.
Reference numeral 6 denotes wiring provided on the flexible substrate 11.

As described above, a step is provided in one of the first lead 2 and the second lead 3 for the laser chip and is formed asymmetrically, so that even a very small semiconductor laser can be used. , Its lead spacing is relatively wide,
For example, a capacitor for preventing electrostatic destruction that discharges static electricity or the like can be connected between the leads of the laser chip in a portion exposed from the frame. That is, for example, even if a capacitor for preventing electrostatic destruction is connected near the laser chip inside the frame, if there is not much difference in inductance between the laser chip and the capacitor, the laser is discharged before the capacitor discharges static electricity. The static electricity is also applied to the chip to destroy the laser chip, and there is no effect unless an inductance element is connected in series to the laser chip.

On the other hand, if a capacitor is connected to a portion where the static electricity always passes as far as possible from the laser chip, the static electricity can be discharged by the capacitor before the static electricity advances due to the inductance from the position of the capacitor to the position of the laser chip. The laser chip can be protected. In most cases, this type of semiconductor laser is destroyed by static electricity. For example, when a semiconductor laser is mounted on a flexible substrate, static electricity charged on the flexible substrate is applied from the lead end. By discharging, an effect of preventing electrostatic breakdown of the laser chip can be obtained. In the semiconductor laser having the above-described structure, the lead from the lead end to the laser chip passes through fine leads and wire bonding, so that a time delay occurs in the progress of static electricity. Therefore, by connecting the capacitor to the lead end, static electricity is discharged by the capacitor before reaching the laser chip, and the laser chip is protected from the capacitor.

It is preferable that this capacitor is directly attached to the lead with a conductive agent such as solder so as not to generate inductance. However, conventionally, the interval between the leads is narrow, and a capacitor for preventing electrostatic breakdown is connected without generating inductance. I couldn't. However, by providing a step on the above-mentioned leads, the lead interval is widened, and a capacitor for preventing electrostatic breakdown can be directly mounted between the leads of the laser chip, which can greatly contribute to prevention of electrostatic breakdown.

In the above-mentioned example, the total number of leads is three. However, as shown in FIG. 3, two laser chips are inserted and connected to the second leads 3a and 3b, respectively. In some cases, the first lead 2 is not used as a common lead, but is provided separately and may be four or more. However, even in this case, one or two of the leads are formed. Can be formed to be asymmetric. Also in this case, the through holes 12, 13a, 13b, 1
By forming the position of 4 in accordance with the position of the lead of the semiconductor laser, it is possible to automatically assemble components having different directions.

As described above, if a step is formed in the lead to make the center asymmetric with respect to the center, a capacitor for preventing electrostatic breakdown can be connected. However, in order to solve the problem that the upper and lower parts cannot be distinguished when inserted together with the diffraction grating in the cylindrical holder, the end of the lead is asymmetrical with respect to the center without providing a step on the lead. I just need to be. As an example of this, for example, as shown in a bottom view of a semiconductor laser similar to FIG. 1B in FIG. 4, the width of the lead 3 is made wider than the widths of the other leads 2 and 4, and By changing the size of through-holes such as flexible substrates,
When the semiconductor laser is turned in the opposite direction, the same effect of preventing a problem that the lead is not inserted into the through hole and the semiconductor laser is mounted on the flexible substrate upside down can be obtained.
It is to be noted that the width of the lead is not limited to be changed, and the lead may be formed to have a different cross-sectional shape, and a through-hole or the like of a flexible substrate may be formed in accordance with the cross-sectional shape.

[0023]

As described above, according to the present invention,
Even if a molded semiconductor laser, such as that used in an optical pickup device, is inserted together with a diffraction grating into a cylindrical holder, it cannot be mounted if it is turned upside down when mounted on a flexible substrate or the like. In addition to eliminating the need for extra nerves during assembly, cost reduction can be achieved by improving yield and reducing man-hours.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a molded semiconductor laser according to the present invention.

FIG. 2 is an explanatory sectional view showing a modification of FIG. 1;

FIG. 3 is an explanatory diagram of the present invention when there are four leads.

FIG. 4 is an explanatory view showing another embodiment of a molded semiconductor laser according to the present invention.

FIG. 5 is an explanatory view showing a structural example of a conventional molded semiconductor laser.

FIG. 6 is an explanatory view of a state in which a conventional molded semiconductor laser is inserted into a holder.

[Explanation of symbols]

 2-4 Lead 5 Light receiving element 6 Frame 8 Laser chip 9 Capacitor

Claims (3)

[Claims] A first pad having a die pad formed at one end thereof;
, A laser chip bonded to the die pad portion, a second lead electrically connected to an electrode of the laser chip, and one end of a plurality of leads including at least the first and second leads A frame made of resin that holds the sides integrally, so that the arrangement of the other ends of the plurality of leads extending from the frame body in a plane perpendicular to the leads is asymmetric with respect to the center point thereof. A molded semiconductor laser in which the plurality of leads extend from the frame. 2. A method according to claim 1, wherein at least one of said plurality of leads is provided.
The arrangement of the other ends of the plurality of leads is formed asymmetrically by forming the book in or out of the frame so that the book has a step with another row of leads. A semiconductor laser as described in the above. 3. At least one of the plurality of leads
3. The semiconductor laser according to claim 1, wherein the cross-sectional shape of the book is different from the cross-sectional shape of the other leads, so that the other ends of the plurality of leads are asymmetrically arranged.