JP2005026584A - Laser module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser module which can curtail a parasitic inductance in a lead pin or a bonding wire, and can modulate an intensity at a high speed. <P>SOLUTION: The laser module comprises a stem 1, a heat sink 2 fitted on the stem, a laser chip 6 disposed on the heat sink, lead pins 3, 4 which are penetrated through the stem in a state of being electrically insulated from the stem to fix, a bendable flexible board 5 which has a conductive pattern for feeding electricity from the lead pin to the laser chip, and a connecting means 7 for electrically connecting the laser chip with the flexible board. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser module used in communication equipment, optical disc equipment, and the like, and more particularly to a laser module called a can package type (stem type).
[0002]
[Prior art]
Conventionally, a can package type (stem type) laser module (hereinafter referred to as a can package type laser module) has been developed. A conventional can package type laser module will be described below with reference to FIG.
[0003]
As shown in FIG. 3, a heat sink 102 is attached on the stem 101. A substrate 105 is fixed and connected on the heat sink 102, and a laser chip 106 is mounted on the substrate 105. The cathode terminal on the bottom surface of the laser chip 106 is connected to the substrate 105 with conductive solder or the like. The lead pin 103 and the pattern on the substrate 105 are connected by a bonding wire 108, and the lead pin 104 and the anode of the laser chip 106 are connected by a bonding wire 107. Here, when a laser drive current is applied from the lead pin 103 to the lead pin 104, the laser chip 106 emits light according to the drive current. Such a can package type laser module is described in Patent Document 1 below.
[0004]
[Patent Document 1]
JP 2000-353846 A (paragraph 0015)
[0005]
[Problems to be solved by the invention]
However, in the conventional can package type laser module as shown in FIG. 3, when the laser driving current is modulated at a high speed, the lead pins 103 and 104 inside the stem 101 and the bonding wires 107 and 108 are long, so that the parasitic inductance is large. There is a problem that the high speed of the drive current supplied to the laser chip 106 is deteriorated and the optical signal output from the laser chip 106 cannot be intensity-modulated at high speed.
[0006]
The present invention has been made to solve the above problem, and an object of the present invention is to provide a laser module that can reduce parasitic inductance generated in a lead pin and a bonding wire and can perform intensity modulation at high speed.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a stem, a heat sink, a laser chip, a lead pin, a flexible substrate that can be bent, and connection means for electrically connecting the laser chip and the flexible substrate. That is, according to the present invention, the stem, the heat sink attached to the stem, the laser chip disposed on the heat sink, and the stem are fixed while penetrating through the stem while being electrically insulated from the stem. A laser module comprising: a lead pin that has a conductive pattern for supplying a current from the lead pin to the laser chip; and a connection unit that electrically connects the laser chip and the flexible substrate. Is provided. With this configuration, it is possible to reduce the parasitic inductance generated in the lead pin and the bonding wire and perform the intensity modulation at a high speed.
[0008]
Moreover, it is a preferable aspect of the present invention that the flexible substrate constituting the laser module of the present invention is surface-connected to the plane on the stem and the plane on the heat sink. With this configuration, there is no deviation of the optical axis of the laser chip, and the high-frequency impedance of the transmission line on the flexible substrate can be stabilized.
[0009]
Moreover, it is a preferable aspect of the present invention that the flexible substrate constituting the laser module of the present invention has a ground pattern on at least a part of the other surface having the conductive pattern. With this configuration, the high frequency impedance of the transmission line on the flexible substrate can be stabilized.
[0010]
Moreover, it is a preferable aspect of the present invention that the heat sink and the flexible substrate constituting the laser module of the present invention are connected by a conductive substance. With this configuration, there is no deviation of the optical axis of the laser chip, and the high-frequency impedance of the transmission line on the flexible substrate can be stabilized.
[0011]
Moreover, it is a preferable aspect of the present invention that a stopper for fixing the flexible substrate constituting the laser module of the present invention at a predetermined position is provided on at least one of the heat sink or the stem. With this configuration, there is no deviation of the optical axis of the laser chip, and the high-frequency impedance of the transmission line on the flexible substrate can be stabilized.
[0012]
Moreover, it is a preferable aspect of the present invention that a light receiving element for laser output monitoring is arranged on the flexible substrate constituting the laser module of the present invention. With this configuration, mounting can be facilitated.
[0013]
In addition, it is a preferable aspect of the present invention that the connecting means constituting the laser module of the present invention is such that the cathode side of the laser chip is a conductive material and the anode side of the laser chip is a bonding wire. . With this configuration, it is possible to reduce the parasitic inductance generated in the lead pin and the bonding wire and perform the intensity modulation at a high speed.
[0014]
Moreover, it is a preferable aspect of the present invention that the anode terminal or the cathode terminal of the laser chip constituting the laser module of the present invention is electrically short-circuited from the stem. With this configuration, the high frequency characteristics of the laser chip can be improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Hereinafter, a laser module according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a laser chip 6 is mounted on the stem 1, and a heat sink 2 that radiates heat from the laser chip 6 is attached. Further, lead pins 3 and 4 for supplying a driving current for the laser chip 6 penetrate the stem 1 in a state of being electrically insulated from the stem 1. For example, glass can be used as the means for electrical insulation. The flexible substrate 5 bent in a substantially L shape is surface-connected to the stem 1 and the heat sink 2. As this connection method, for example, soldering can be used.
[0016]
The flexible substrate 5 has a ground pattern on at least a part of the other surface having the conductive pattern. This ground pattern can stabilize the high-frequency impedance of the transmission line on the flexible substrate 5. On the flexible substrate 5, a light receiving element 10 for monitoring a laser chip output (hereinafter referred to as a light receiving element 10) is disposed. The light intensity output from the laser chip 6 can be monitored by the light receiving element 10. Here, since the flexible substrate 5 can be bent, the flexible substrate 5 is connected to the stem 1 and the heat sink 2 after the light receiving element 10 is disposed at a predetermined position on the flexible substrate 5. Thereby, mounting of the light receiving element 10 can be facilitated.
[0017]
The current for driving the laser chip 6 flows from the lead pin 4 through the conductive pattern on the flexible substrate 5 to the anode side of the laser chip 6 connected to the conductive pattern by solder or the like. The current that flows to the anode side of the laser chip 6 flows from the cathode side of the laser chip 6 to the lead pin 3 through the bonding wire 7 through the conductive pattern on the flexible substrate 5. In this way, the laser driving current is supplied. The light intensity of the laser chip 6 changes by changing the laser driving current. Here, the present invention can be implemented even when the anode terminal or the cathode terminal is electrically short-circuited from the stem 1. By electrically short-circuiting, the high frequency characteristics of the laser chip 6 can be improved when the laser module is grounded (GND). Moreover, even if resistance is arrange | positioned in series in the middle of the electroconductive pattern on the flexible substrate 5, it can implement. Impedance matching can be achieved by arranging the resistors. As this resistor, for example, a thin film resistor can be used.
[0018]
With the above-described configuration, the lead pins 3 and 4 and the bonding wire 7 can be shortened. Therefore, the parasitic inductance generated in the lead pins 3 and 4 and the bonding wire 7 can be reduced, and laser capable of intensity modulation at high speed. Module becomes feasible.
[0019]
<Second Embodiment>
Next, a laser module according to a second embodiment of the present invention will be described with reference to FIG. The laser module of FIG. 2 is provided with stoppers 8 and 9 for fixing the position of the flexible substrate 5 to the laser module according to the first embodiment. The stoppers 8 and 9 can easily fix the position when the flexible substrate 5 is mounted. Here, as means for fixing the stoppers 8 and 9 to the stem 1 and the heat sink 2, for example, solder can be used. Moreover, as a material of the stoppers 8 and 9, for example, metal or plastic can be used. The stoppers 8 and 9 are not limited to those described above. For example, as long as the position of the flexible substrate 5 can be easily fixed, the embodiment can be implemented without using the shape shown in FIG.
[0020]
The constituent elements of the laser module shown in FIG. 2 other than the stoppers 8 and 9 are the same as the constituent elements of the laser module according to the first embodiment, and a description thereof will be omitted.
[0021]
【The invention's effect】
As described above, in the present invention, a stem, a heat sink attached to the stem, a laser chip disposed on the heat sink, and a lead that is fixed through the stem while being electrically insulated from the stem. It is generated in a lead pin or a bonding wire because it includes a pin, a flexible flexible substrate having a conductive pattern for supplying current from the lead pin to the laser chip, and connection means for electrically connecting the laser chip and the flexible substrate. Parasitic inductance can be reduced and intensity modulation can be performed at high speed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a laser module according to a first embodiment of the present invention. FIG. 2 is a diagram showing a laser module according to a second embodiment of the present invention. Diagram showing modules 【Explanation of symbols】
1, 101 Stem 2, 102 Heat sink 3, 4, 103, 104 Lead pin 5 Flexible substrate 6, 106 Laser chip 7, 107, 108 Bonding wire (connection means)
8, 9 Stopper 10 Light receiving element 105 Substrate

Claims (8)

Stem,
A heat sink attached to the stem;
A laser chip disposed on the heat sink;
A lead pin that is fixed through the stem while being electrically insulated from the stem;
A bendable flexible substrate having a conductive pattern for supplying current from the lead pin to the laser chip;
A laser module comprising connection means for electrically connecting the laser chip and the flexible substrate. The laser module according to claim 1, wherein the flexible substrate is surface-connected to a plane on the stem and a plane on the heat sink. The laser module according to claim 1, wherein the flexible substrate has a ground pattern on at least a part of the other surface of the surface having the conductive pattern. The laser module according to any one of claims 1 to 3, wherein the heat sink and the flexible substrate are connected by a conductive substance. The laser module according to any one of claims 1 to 4, wherein a stopper for fixing the flexible substrate at a predetermined position is provided on at least one of the heat sink and the stem. The laser module according to claim 1, wherein a light receiving element for laser output monitoring is disposed on the flexible substrate. 7. The laser module according to claim 1, wherein the connection means includes a conductive material on a cathode side of the laser chip and a bonding wire on an anode side of the laser chip. The laser module according to any one of claims 1 to 7, wherein an anode terminal or a cathode terminal of the laser chip is electrically short-circuited from the stem.

Images