JPH11109187A - Optical semiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semi-conductor module capable of stably performing silicon substrate junction in a resin mold package and stably operating a semi- conductor element and excellent in reliability by specifying the ratio of the width of a substrate member in the direction perpendicular to the light transmitting direction of an optical fiber to be mounted on the substrate member, to the width of a package having a lead terminal in the same direction. SOLUTION: The ration of the width of a substrate member in the direction perpendicular to the light transmitting direction of a optical fiber 13 to be mounted on a substrate member 3 to the width of a package 4 having a lead terminal 5 in the same direction is set to be 0.24-0.42. The heat in a semiconductor element can be efficiently radiated to the lead terminal of the package through the substrate member. When the ratio is increased and the junction area is increased, a peeling is generated between the substrate member and the package, and the heat transfer efficiency between the substrate member and the package is worsened. When the ratio is reduced, the joining area is reduced, the heat transmission becomes small, and the heat transfer efficiency is also worsened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical semiconductor module which is used, for example, in optical communication and includes a semiconductor element and an optical fiber optically coupled to the semiconductor element.

[0002]

2. Description of the Related Art Heretofore, as a technique relating to the structure of this type of optical semiconductor module, there is a report, for example, from the Institute of Electronics, Information and Communication Engineers, General Conference C-216, 1996.

According to this prior art, a silicon substrate on which a laser diode, which is a semiconductor element, and an optical fiber are mounted,
It is a structure mounted inside a hollow resin mold package or ceramic package. The connection between the laser diode and the optical fiber is performed by attaching the laser diode using a marker on the silicon substrate as a mark and fixing the optical fiber in the V groove for mounting the fiber.

[0004]

However, the above prior art has the following problems.

That is, in the above prior art, a silicon substrate on which a laser diode is mounted is mounted in a resin mold package or a ceramic package. In order to stably operate the laser diode, it is important to efficiently radiate heat generated when the laser element is driven and prevent the temperature of the laser diode from rising. Since the above-mentioned conventional technology is a resin mold package or a ceramic package having a lower thermal conductivity than a metal package, sufficient heat radiation cannot be expected.

For this reason, it is necessary to efficiently radiate heat from the lead terminals bonded to the printed circuit board. However, when heat is transmitted from the laser diode to the lead terminals via the silicon substrate, the bonding state between the silicon substrate and the package is reduced. Determines the efficiency of heat transfer. That is, if the bonding state between the silicon substrate and the package is poor, the heat radiation efficiency to the lead terminal side decreases, and the temperature of the laser diode increases.

[0007] As described above, the bonding of the silicon substrate into the package is a very important bonding portion for stably operating the laser diode.

An object of the present invention is to propose a relationship between a package and a substrate member shape for stably bonding a substrate member in a resin mold package, and to provide a highly reliable optical semiconductor module capable of stably operating a semiconductor element. It is in.

[0009]

An optical semiconductor module is used as a light source for optical communication and optically couples a semiconductor element with an optical fiber. In order to reduce the cost of the optical semiconductor module, it is necessary to reduce the components and the manufacturing cost of the module. Proposals and development of a structure in which a V-groove is formed on a silicon substrate and hybrid mounting is performed so that a semiconductor element and an optical fiber perform optical coupling have been activated, and cost reduction of a module has been studied. However, sufficient consideration has not been given to a module taking into consideration the shape of a silicon substrate mounted in a resin mold package, in particular, the heat dissipation of a semiconductor element.

The present invention proposes a relationship between a package for stably bonding a silicon substrate into a resin mold package and a shape of the silicon substrate to obtain a highly reliable optical semiconductor module capable of stably operating a semiconductor element. It is.

According to the present invention, a semiconductor device, an optical fiber optically coupled to the semiconductor device for performing optical transmission, and the semiconductor device and the optical fiber are provided. In an optical semiconductor module having a substrate member provided with a V groove for mounting an optical fiber mounted on the same substrate, and a package with lead terminals for accommodating and installing these substrate members, an optical fiber module mounted on the substrate member has The dimension of the board member width in the direction perpendicular to the propagation direction and the width of the package with lead terminals in the same direction is the following: board member width / package width = 0.24 to 0.4.
An optical semiconductor module is provided, which is characterized by the relationship of 2.

According to another aspect of the present invention, there is provided a semiconductor device comprising: a semiconductor device; an optical fiber optically coupled to the semiconductor device for performing optical transmission; and the semiconductor device and the optical fiber. In an optical semiconductor module having a substrate member provided with a V groove for mounting an optical fiber mounted on the same substrate, and a package having lead terminals for accommodating and installing these substrate members, a lead terminal taking-out direction of the package with lead terminals Wherein the relation between the package width and the length of the substrate member in the same direction is substrate member width / package width = 0.24 to 0.42. Is done.

An optical semiconductor module according to the present invention has one of the following features.

A semiconductor device, an optical fiber optically coupled to the semiconductor device for optical transmission, and a V-groove for mounting the semiconductor device and the optical fiber on the same substrate. In an optical semiconductor module having a substrate member and a package with lead terminals for accommodating and installing these substrate members, a width of the substrate member in a direction perpendicular to a light propagation direction of an optical fiber mounted on the substrate member is the same as the width of the substrate member. Dimensions of the package with lead terminals and the width of the substrate member / package width = 0.24 to 0.42;
Being a relationship.

A semiconductor device, an optical fiber optically coupled to the semiconductor device for optical transmission, and a V-groove for mounting the optical fiber for mounting the semiconductor device and the optical fiber on the same substrate. In an optical semiconductor module having a substrate member and a package with lead terminals for accommodating and installing these substrate members, a package width in a lead terminal take-out direction of the package with lead terminals and a width of the substrate member in the same direction as the package width. The relationship of the lengths is that the width of the board member / the width of the package = 0.24 to 0.42.

In the present invention configured as described above,
The relationship between the width of the substrate member on which the semiconductor element and the optical fiber are mounted and the width of the package with lead terminals is such that the substrate member width / package width = 0.24 to 0.42. Thereby, the heat of the semiconductor element can be efficiently radiated to the lead terminals of the package through the substrate member.

In other words, when the bonding ratio is increased by increasing the above ratio, especially in a resin mold package, if the coefficient of thermal expansion of the board member and the package is significantly different, thermal strain will be applied to the joint in the module temperature cycle test. In addition, peeling occurs, or when the module is mounted on a printed circuit board, the module is deformed and peeling occurs between the board member and the package, so that the efficiency of heat transfer between the board member and the package deteriorates. Conversely, when the above ratio is reduced, the bonding area is reduced, so that the bonded portion does not peel off due to thermal strain or module deformation, but the heat spread is reduced and the heat transfer efficiency between the substrate member and the package is also poor. Become.

Moreover, since the bonding area is small, stable bonding cannot be performed. The relationship between the board member width / package width = 0.24 to 0.42 shown above indicates that when a package is formed using a resin mold, even if heat distortion due to a temperature cycle test or module deformation at the time of mounting a printed board occurs. In addition, the stress applied to the joint portion of the substrate member is low and the dimensional relationship ratio is hard to be removed from the package, and the shape has no problem in handling and assembling. Therefore, the bonding state between the substrate member and the package is improved, and heat radiation during driving of the semiconductor element can be efficiently transmitted to the lead terminals.

As described above, it is possible to stably bond the silicon substrate into the resin mold package and obtain a highly reliable optical semiconductor module capable of stably operating the semiconductor element.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. It should be noted that some of the metallized wirings, wire bonding leads and adhesives are not shown in order to avoid complication. Further, in the embodiment of the present invention, a description is given using a laser diode as a semiconductor light emitting element and a photodiode as a semiconductor light receiving element as semiconductor elements and a single mode optical fiber as an optical fiber.

FIGS. 1 to 3 show a first embodiment of the present invention.
This will be described below.

FIG. 1 is a perspective view showing the structure of the optical semiconductor module according to the present embodiment, and FIG. 2 is a longitudinal sectional view taken along the line aa 'of FIG. 1 showing the structure in which the optical semiconductor module is mounted on a socket substrate. FIG. 3 is a diagram showing the stress at the silicon substrate joint.

In FIG. 1, an optical semiconductor module is a laser diode 1 which is a semiconductor element.
A photodiode 2, which is a semiconductor light receiving element; an optical fiber 13, which is a single mode fiber for optically coupling with the laser diode 1 to perform optical transmission; an optical fiber on which the laser diode 1 and the photodiode 2 are mounted; A silicon substrate 3 on which a V-shaped groove 9 for installing the fiber 13 is formed, and a pad portion 8 for bonding and fixing the silicon substrate 3
And a lead terminal 5 electrically connected to the pad portion 8, and these are housed in a hollow package 4 formed by resin molding.

The silicon substrate 3 is bonded and fixed to the pad 8 in the package 4. The bonding position of the silicon substrate 3 is a position where the central axis of the silicon substrate 3 and the central axis of the package 4 substantially coincide. A V-groove 9 for mounting the optical fiber 13 is formed on the upper surface of the silicon substrate 3 by anisotropic etching.
5 is joined. On the other hand, on the upper surface of the silicon substrate 3,
A metallized wiring (not shown) is patterned, and a laser diode 1 and a photodiode 2 are mounted at predetermined positions on the wiring.

The laser diode 1 and the photodiode 2 are mounted with markers (not shown) formed on metallized wiring on the silicon substrate 3 as marks. Wire bonding leads (not shown) are attached to the laser diode 1 and the photodiode 2 via metallized wiring on the upper surface of the silicon substrate 3 so as to be electrically connected to the lead terminals 5. The V-groove 9 formed in the silicon substrate 3 has a predetermined width such that when the optical fiber 13 is installed, the central axis of the optical fiber 13 is the same as the laser emission axis of the laser diode 1 mounted on the upper surface of the silicon substrate 3. And the depth.

The silicon substrate 3 on which the laser diode 1, photodiode 2, and optical fiber 13 are mounted is housed in a resin-molded hollow package 4. The optical fiber 13 taken out of the package 4 is attached to an optical fiber installation groove 6 and an optical fiber coating installation groove 7 provided on the side wall of the package 4 and having different widths and depths. Here, a copper alloy is used as a material forming the pad portion 8 and the lead terminal 5, and the pad portion 8 supports the lead terminals 5 on both sides. The lead terminal 5 connected to the pad portion 8 is at least one on one side.

A metallized wiring is formed on the upper surface of the silicon substrate 3 by sputtering in advance, and the laser diode 1 and the photodiode 2 are bonded and fixed on the wiring, and are respectively connected by wire bonding leads. The laser diode 1 is positioned between the central axis of the optical fiber 13 installed in the V groove 9 of the silicon substrate 3 and the laser diode 1.
Are fixed so as to be aligned with the laser emission axis. Further, the laser diode 1 is mounted with the laser emission position arranged on the upper surface side of the silicon substrate 3 so as to reduce the height variation of the laser emission position when the laser diode 1 is bonded and fixed to the upper surface of the silicon substrate 3.

The package 4 has a configuration in which the lead terminals 5, the pad portion 8, and the grooves 6, 7 on the side wall of the package 4 are integrally formed by resin molding. The grooves 6 and 7 on the side wall are provided at one end of the package 4, and the width and depth of the optical fiber installation groove 6 for holding and fixing the optical fiber 13 and the optical fiber coating installation groove 7 for holding and fixing the optical fiber coating 14 are different. It has a stepped shape. A step 10 is provided on the upper surface of the package 4 so that the cap can be attached to a predetermined position. Here, the package 4 has a thickness of 2.6 mm, a width of 6 mm, and a length of 21 mm.

FIG. 2 is a longitudinal sectional view of a structure in which the optical semiconductor module is mounted on the socket substrate 12. This is a shape in which the lead terminal 5 of the optical semiconductor module shown in FIG. Silicon substrate 3
Is bonded to a substantially central position of the package 4 and is electrically connected to the lead terminals 5 from above the silicon substrate 3 by wire bonding leads 11. As you can see from the figure,
When the optical semiconductor module is mounted on the socket substrate 12 with both ends supported by the socket substrate 12,
2 is subjected to an external force from the direction or the direction shown in FIG.
Is deformed like the deformation or deformation on the right side in the figure.

When the pad portion 8 is deformed, a force is applied so as to peel off the bonding portion of the silicon substrate 3. here,
The width of the silicon substrate 3 (a in the figure) is 1.5 mm, the width of the package 4 (b in the figure) is 6.0 mm, and the relationship is silicon substrate width / package width = 0.25.
With this relationship, even if the pad portion 8 is deformed, a large deformation or force that peels off the bonding portion of the silicon substrate 3 is not applied.

FIG. 3 shows the width of the silicon substrate 3 and the package 4.
FIG. 4 is a diagram showing stress applied to a silicon substrate 3 bonding portion with respect to a width relationship. In the figure, the vertical axis indicates the relative ratio of the stress generated at the junction of the silicon substrate 3, and the horizontal axis indicates the relative ratio of the width of the silicon substrate 3 to the width of the package 4. According to this, as the relative ratio of the horizontal axis increases, the stress generated at the bonding portion of the silicon substrate 3 also increases.

That is, when the bonding area of the silicon substrate 3 to the pad portion 8 in the package 4 increases, the pad portion 8
As a result, stress that tends to peel off the joint between the silicon substrate 3 and the pad portion 8 is particularly large at the edge of the silicon substrate 3. Conversely, if the relative ratio is small, the pad portion 8
The bonding area of the silicon substrate 3 with respect to
The stress generated at the junction of the silicon substrate 3 is reduced.

However, on the other hand, there are concerns about problems such as insufficient bonding strength being obtained, and difficulty in handling and assembling. Therefore, as a range in which a high stress for peeling off the bonding portion of the silicon substrate 3 is not applied and the handling and assembling can be easily performed, the relative ratio of the width of the silicon substrate 3 to the width of the package 4 is 0.24 to 0.42. It can be said that the area is appropriate.

In this case, the stress generated at the bonding portion of the silicon substrate 3 is about half the relative ratio of 0.75 on the horizontal axis, and is smaller than the shear strength of the bonding member for bonding the silicon substrate 3 to the pad portion 8. It is a stress value. Where, for example,
If the package 4 is 6.0 mm wide, the silicon substrate 3
The appropriate width is 1.5 to 2.5 mm. The maximum width of the package 4 is about 6.2 mm because the distance between the bent lead terminals 5 is adjusted to be an inch pitch.

In the present embodiment configured as described above, the relationship between the width of the silicon substrate 3 on which the laser diode 1 and the optical fiber 13 are mounted and the width of the package 4 with the lead terminals 5 is expressed as silicon substrate width / package. Width = 0.2
4 to 0.42. Thereby, the stress generated at the junction between the silicon substrate 3 and the pad portion 8 is reduced,
It is possible to obtain a joint that does not peel off. That is, since the bonding of the silicon substrate 3 can be performed well, the laser diode 1 can be mounted without lowering the efficiency of heat transfer.
Can be efficiently radiated to the lead terminals 5 of the package 4 through the silicon substrate 3.

Therefore, it is possible to stably bond the silicon substrate 3 to the inside of the package 4 formed by the resin mold, and obtain a highly reliable optical semiconductor module capable of stably operating the laser diode 1.

In the first embodiment, the optical semiconductor module is mounted on the socket substrate 12. However, the present invention is not limited to this. For example, when the optical semiconductor module is mounted on a printed circuit board, an IC socket, or the like. However, since the deformation of the pad portion 8 due to the module mounting or the temperature cycle test occurs in the same manner, the same effect as that of the first embodiment can be obtained even when the pad portion 8 is mounted on a printed circuit board or an IC socket. it can.

[0038]

According to the present invention, the relationship between the width of a silicon substrate on which a laser diode is mounted and the width of a package with lead terminals is determined by the following formula: silicon substrate width / package width = 0.2.
4-0.42. As a result, the stress generated at the junction between the silicon substrate and the pad portion can be reduced, and a good junction without peeling of the junction can be obtained, so that the heat of the laser diode can be reduced without lowering the efficiency of heat transfer. Heat can be efficiently dissipated to the lead terminals of the package through the silicon substrate.

Therefore, a highly reliable optical semiconductor module capable of stably bonding a silicon substrate to a package formed by a resin mold and stably operating a laser diode can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of an optical semiconductor module according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure in which the optical semiconductor module according to the first embodiment of the present invention is mounted on a socket;
It is sectional drawing a '.

FIG. 3 is a graph showing a relationship between a stress applied to a silicon substrate bonding portion and a relative ratio between a silicon substrate width and a package width according to the first embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser diode, 2 ... Photodiode, 3 ... Silicon substrate, 4 ... Package, 5 ... Lead terminal, 6 ... Optical fiber installation groove, 7 ... Optical fiber coating installation groove, 8 ... Pad part, 9 ... Optical fiber mounting V-groove, 10: Cap fixing step, 11: Wire bonding lead, 12: Socket substrate, 13: Optical fiber, 14: Optical fiber coating,
15 ... Adhesive.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Ishii 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratories Co., Ltd. 292 Hitachi Manufacturing Co., Ltd.Production Technology Research Laboratory (72) Inventor Shoichi Takahashi

Claims (1)

[Claims] A semiconductor device, an optical fiber optically coupled to the semiconductor device for optical transmission, and a V-groove for mounting the optical fiber on which the semiconductor device and the optical fiber are mounted on the same substrate. In an optical semiconductor module having a substrate member provided and a package with lead terminals for housing and installing these substrate members, a substrate member width in a direction perpendicular to a light propagation direction of an optical fiber mounted on the substrate member, and The dimensions with the width of the package with lead terminals in the same direction are: board member width / package width = 0.24 to 0.42,
An optical semiconductor module, characterized in that: